Molecular recognition via thermo-regulatory oscillations in covalent organic frameworks

Abstract

A microporous crystalline lattice composition formed by a plurality of chemical subunits bound by a series of cross-linked covalent tetraphenoxyb orate linkages and weak ion-dipole interactions forming an ionic covalent organic framework (ICOF) having a plurality of tunable iso-surface channels.

Description

[0001] MOLECULAR RECOGNITION VIA THERMO-REGULATORY OSCILLATIONS IN COVALENT ORGANIC FRAMEWORKS

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS

[0003] This International PCT Application claims the benefit of and priority to U.S. Provisional Application No. 63 / 541,263, filed September 28, 2023, and U.S. Provisional Application No. 63 / 633,539, filed April 12, 2024, both of which are incorporated herein by reference in their entirety.

[0004] STATEMENT OF GOVERNMENT INTEREST

[0005] This invention was made with government support under grant number 2108197 awarded by the National Science Foundation. The government has certain rights in the invention. TECHNICAL FIELD

[0006] The present invention is directed to the field of microporous crystalline materials, and in particular microporous crystalline materials using tetraphenoxyb orate linkages to synthesize a series of ionic covalent organic frameworks (ICOFs) that include iso-surface channels that exhibit continuous and reversible tunability between 2.9 to 4.0 A, with resolution below 0.2 A. BACKGROUND

[0007] Microporous crystalline materials, such as metal / covalent organic frameworks (MOFs / COFs) and zeolites, have applications in sensing (1, 2), catalysis (3-6), and molecular separation (7-9). Conventionally, reticular chemistry (10, 11) and post synthesis modifications (12, 13) are employed to obtain specific pore sizes that meet the requirements of the target applications. Occasionally, some of these materials exhibit flexibility with stimuli-induced pore shape / size tunability (14, 15), enabling pore adjustment within a single material to accommodate target applications. Flexibility in such materials typically arises from substantial movement of weak bonds (e g., coordination bonds in MOFs (15, 16)) in response to external stimuli, such as the adsorption of molecules (17), changes in temperature (18, 19), or alternations in pressure (20). This usually triggers relatively large pore size change (3-5 A), exceeding the critical sub-A scale required for selective recognition of small molecules (16, 21, 22). It is challenging to obtain such tunability within the sub-A scale. Materials that rely on local molecular motion can achieve pore adjustment appropriate for molecular separation, for example, to differentiate isotopes (18, 23, 24) or small hydrocarbons (25). These materials differentiate molecules via diffusion rate difference, which depends on the differences in mass instead of size (18, 24, 25). However, it remains a challenge to differentiate small molecules based on their true shape and size using crystalline materials with reversible, continuously adjustable pores. This is because achieving pores that fall exactly between the sizes of two molecules requires ultra-high precision tunability. This necessitates meticulous material design, which involves a delicate balance between structural rigidity to maintain long-range order and weak molecular motion to allow for local flexibility.

[0008] Among potential dynamic covalent linkages to construct such precisely tunable crystalline materials, borate chemistry is particularly promising (26-28). The reversible B-0 bond allows precise synthesis of long-range crystalline or even single-crystalline materials, for example, helical covalent polymers (HCP) and COFs (28-30). The tetra-oxygen-bonded borate, in particular, has increased local flexibility due to tetrahedral conformation and secondary ionic interactions; for instance, the dihedral angle of the tetraborate linkage gets distorted from 90° to 66° in the HCP (30). These unique properties of tetraoxy borate linkage provides potential to construct structures having both long-range crystallinity and local flexibility.

[0009] Herein, Applicants report a facile strategy of combining covalent polymerization with interlayer ion-dipole interaction in a crystalline material to achieve meticulous balance of long- range structural rigidity and local molecular flexibility. Applicants utilized boron chemistry to synthesize a series of crystalline ionic covalent organic frameworks (ICOFs) (Fig. 1A). These ICOFs exhibit reversible, ultra-precise pore tunability with resolution below 0.2 A. Their tunable pore size is determined by the fast oscillations of linkers, whose amplitude changes continuously with temperature. This allows ICOFs to differentiate gas molecules having sub-A size differences, demonstrating promise for size-based separation of challenging complex mixtures, and in particular complex gas pairs, such as O2 / N2 and N2 / CH4.

[0010] SUMMARY OF THE INVENTION

[0011] In one aspect, the present invention provides systems, methods, and compositions for the novel use of tetraphenoxyborate linkages to synthesize a series of ionic covalent organic frameworks (ICOFs) that maintain meticulous synergy between structural rigidity and local flexibility. The invention allows thermodynamic pores in ICOFs to achieve continuous and reversible (approximately at least 100 thermal cycles) tunability between 2.9 to 4.0 A, with resolution below 0.2 A, resulting from gradual amplitude change of linker oscillation regulated by temperature. These thermoelastic apertures selectively block larger molecules over marginally smaller ones, demonstrating size-based molecular recognition, which can allow separation of complex mixtures, and in particular complex gas mixtures, such as O2 / N2 and N2 / CH4, with high adsorptive selectivity.

[0012] In another aspect, the present invention includes a microporous crystalline lattice composition comprising a plurality of chemical subunits bound by a series of cross-linked covalent tetraphenoxy borate linkages and weak ion-dipole interactions forming an ionic covalent organic framework (ICOF) having a plurality of tunable iso-surface channels. In a preferred embodiment, wherein said chemical subunits are selected from:

[0013] (

[0014] (Formula II, also referred to as ICOF-102-Na+or Li+)

[0015] (Formula III, also referred to as ICOF-101-Na+or Li+) wherein, X+is a metal ion, preferably selected from Na+or Li+) In another aspect, the present invention includes turning iso-surface channels of an ionic covalent organic framework (ICOF) to selectively adsorb a gas compound via thermo-regulatory molecular sieving (TRMS).

[0016] In another aspect, the present invention includes methods of synthesizing a microporous crystalline lattice composition comprising a plurality of chemical subunits bound by a series of cross-linked covalent tetraphenoxyb orate linkages and weak ion-dipole interactions forming an ionic covalent organic framework (ICOF) having a plurality of tunable iso-surface channels.

[0017] In another aspect, the present invention includes methods of separating method for separating a complex gas mixture using a microporous crystalline lattice composition comprising a plurality of chemical subunits bound by a series of cross-linked covalent tetraphenoxyborate linkages and weak ion-dipole interactions forming an ionic covalent organic framework (ICOF) having a plurality of tunable iso-surface channels.

[0018] Additional embodiments of the current invention will be apparent from the specification, figures and claims further provided herein.

[0019] BRIEF DESCRIPTION OF THE FIGURES

[0020] Fig. 1A-F. Rational design and synthesis of 2D ICOFs. (A) General synthesis strategy for ICOF-lOn-M through the condensation reaction between a variety of diol linkers and boron sources. The n can be 1,2 or 3 depending on the linker as marked on the right side and M is the metal - Na or Li. As an example, the ICOF-101-Na was characterized by FT-IR, 1 IB NMR, and PXRD spectroscopy. (B) FT-IR spectra of 1, sodium borohydride, ICOF-101-Na and NaTB. (C) 11B NMR of NaTB and ICOF-101-Na and (D) Powder XRD patterning of ICOF-101-Na and its refinement. Experimental pattern (red), Pawley refined pattern (black), simulated pattern (azure), Bragg position (green), and difference between observed and refined pattern (navy blue). (E) Crystal structure of ICOF-101-Na, a 2-dimensional extended anionic organic layers an organic layers. They are crosslinked with strong covalent tetraphenborate bond on xy plane and extend in vertical direction through weak ion-dipole interaction, (color code, C: gray; B: blue; Na: brown; O: red). Hydrogens are omitted for clarity. (F) Isoreticular series (ICOF-lOn-M) demonstrates the generalizability of this approach and the tunability of their aperture size. X-ray diffraction patterns show that with increasing length of diol linkers, a shift of (110) peak to lower 20 was observed, while with a decreasing of interlayer distance, the (001) peak shifted to higher 20 area. Fig. 2A-D. Sub-A scale precise thermo-regulatory molecular sieving of ICOFs. (A) Regulation of effective pore-size of ICOF via temperature. Top: expected pore-size distribution (based on isotherms below) changes within the narrow range between 3 and 4 A as shown relative to the gas molecules. Bottom: isotherms for different gases at different temperature (left to right: I: CH4 and N2 at 25°C, II: CH4 and N2 at 50°C, III: N2 and 02 at 55°C, IV: 02 and C02 at 70°C, V: C02 and H2 at 100°C) for ICOF-103-Li. (B) Normalized gas uptake at 1 bar and different temperatures for ICOF-103-Li (top) and ICOF-103-Na (bottom). The gas uptake is normalized by C02 uptake at 25°C and 1 bar. Dashed lines indicate estimated uptake for the gases, normalized by C02 uptake at 25°C and 1 bar. (C) Continuous changing of pore size of ICOF with temperature. The effective pore-size at a given temperature can be predicted following the dashed line. Inset: Magenta region denotes the space occupied by the oscillation of organic linker - occupying more space at higher temperature, yielding smaller effective pore size (top to bottom). (D) Reversible dynamic gating behavior for ICOF-103-Na. C02 uptake at 25°C and 1 bar (normalized by its capacity at cycle 1) over 100 cycles of heating and cooling between 25 and 100°C is measured. Inset: Oscillatory movement of the organic linker in each cycle - change from low amplitude oscillatory state at low temperature to higher amplitude oscillatory state at higher temperature.

[0021] Fig. 3A-D. Computational modeling of temperature dependent structural changes in ICOFs. (A) Left: Structure of ICOF-103-Li depicted from molecular dynamics simulation. The channels formed due to stacking of the layered structure; right: top view and side view of substructure showing the iso-surface at 25°C (in orange) which indicates the actual pore for gas adsorption. The hydrogen gas molecule (placed at top right corner) provides an estimate of the diameter of this iso-surface. (B) Three snapshots of substructures show the oscillation behavior. The angel co is the angle between three boron atoms in xy plane (B-B-B angle) which changes from comin and comax during the oscillation. (C) The amplitude of the linker oscillation increases with temperature, manifesting in larger change from comin and comax at higher temperatures. This increase in the amplitude manifests in pore size change. (D) The aperture size change of ICOF- 103-Li is in the range of size differences of gas molecules.

[0022] Fig. 4A-D. Adsorptive behavior changes of ICOFs upon temperature change and comparison of ICOFs with reported adsorbents. (A) and (B) Ideal selectivity of industrially important gas pairs versus the adsorption capacity of smaller molecules for ICOF-103-Li and ICOF-103-Na, respectively. Open symbols represent results at 25°C; closed symbols represent results at transition temperatures as labelled. Solid big arrows indicate the adsorptive behavior change from affinity -based to size-based. Dashed arrows (and also the size of the symbols) indicate pressure increase (1, 3, 5 and 7 bar). (C) and (D) Adsorptive performance comparison of ICOF and reported adsorbents for N2 / CH4 and O2 / N2 (based on pure component adsorption isotherms). Solid symbols are data at 1 bar, and open symbols are data at higher pressures (3 and 7 bar); Arrows indicate pressure increase. The blue stars in (C) indicate N2 / CH4 mixture gas adsorption performance at 50°C; N2 composition and total pressure: 30 mol.% and 4.2 bar (1), 40 mol.% and 4.3 bar (2), and 50 mol.% 2.9 bar (3). Areas shaded in magenta represent sorbents that are selective for CH4 over N2 or N2 over O2 (affinity -based adsorption).

[0023] Fig. 5. Solid-state 13C NMR spectra of ICOF-101-Na, ICOF-102-Na, and ICOF- 103 -Na. Fig. 6. Solid-state 11B NMR spectra of ICOF-101-Na, ICOF-102-Na, and ICOF-103-Na. Fig. 7. PXRD profiles of ICOF-101-Na experimental result and the simulation of dia topology with different interpenetration degree.

[0024] Fig. 8. Variable Temperature XRD showing no structural distortion of ICOF-101-Na upon heating indicating a stable structure. The samples were heated from 30°C (303K) to ~200°C (473K) with a ramping speed of 5 min °C-1 and cooled back to 30°C. No noticeable peak shift was observed.

[0025] Fig. 9. The FT-IR spectra of 2,6-dihydroxynaphthalene, sodium borohydride, and ICOF- 102-Na.

[0026] Fig. 10. PXRD profiles of ICOF-102-Na experimental result and the simulation of dia topology with different interpenetration degree.

[0027] Fig. 11. Powder XRD patterning of ICOF-102-Na. Experimental pattern (red), Pawley refined pattern (black), simulated pattern (azure), Bragg position (green), and difference between observed and refined pattern (navy blue).

[0028] Fig. 12. The FT-IR spectra of 4,4'-biphenol, sodium borohydride, and ICOF-103-Na.

[0029] Fig. 13. PXRD profiles of ICOF-103-Na experimental result and the simulation of dia topology with different interpenetration degree.

[0030] Fig. 14. Powder XRD patterning of ICOF- 103 -Na. Experimental pattern (red), Pawley refined pattern (black), simulated pattern (azure), Bragg position (green), and difference between observed and refined pattern (navy blue).

[0031] Fig. 15. Solid-state 13C NMR spectra of ICOF-101-Li, ICOF-102-Li, and ICOF-103-Li. Fig. 16. Solid-state 1 IB NMR spectra of ICOF-101-Li, ICOF-102-Li, and ICOF-103-Li.

[0032] Fig. 17. Solid-state 7Li NMR spectra of ICOF-101-Li, ICOF-102-Li, and ICOF-103-Li.

[0033] Fig. 18. The FT-IR spectra of hydroquinone, lithium borohydride, and ICOF-101-Li.

[0034] Fig. 19. Powder XRD patterning of ICOF-101-Li. Experimental pattern (red), Pawley refined pattern (black), simulated pattern (azure), Bragg position (green), and difference between observed and refined pattern (navy blue).

[0035] Fig. 20. The FT-IR spectra of 2,6-dihydroxynaphthalene, lithium borohydride, and ICOF-

[0036] 102-Li.

[0037] Fig. 21. Powder XRD patterning of ICOF-102-Li. Experimental pattern (red), Pawley refined pattern (black), simulated pattern (azure), Bragg position (green), and difference between observed and refined pattern (navy blue).

[0038] Fig. 22. The FT-IR spectra of 4,4'-biphenol, lithium borohydride, and ICOF-103-Li.

[0039] Fig. 23. Powder XRD patterning of ICOF-103-Li. Experimental pattern (red), Pawley refined pattern (black), simulated pattern (azure), Bragg position (green), and difference between observed and refined pattern (navy blue).

[0040] Fig. 24A-F. Thermogravimetric analysis for ICOFs. Mass change and derivative mass change against temperature are plotted for (A) ICOF-101-Na; (B) ICOF-102-Na; (C) ICOF-103- Na; (D) ICOF-101-Li; (E) ICOF-102-Li; and (F) ICOF-103-Li.

[0041] Fig. 25A-F. Nitrogen adsorption-desorption isotherms at 77K for ICOF. Adsorption and desorption points are represented by filled and empty symbols, respectively. Isotherms are shown for (A) ICOF-101-Na; (B) ICOF-102-Na; (C) ICOF-103-Na; (D) ICOF-101-Li; (E) ICOF-102-Li; and (F) ICOF- 103 -Li.

[0042] Fig. 26A-F. BET surface area plot for ICOFs calculated from the corresponding isotherm. BET surface plots for (A) ICOF-101-Na; (B) ICOF-102-Na; (C) ICOF-103-Na; (D) ICOF-101-Li; (E) ICOF-102-Li; and (F) ICOF-103-Li.

[0043] Fig. 27A-G. SEM morphology of the as-synthesized ICOF series including (A) ICOF-101- Na; (B) ICOF-102-Na; (C) ICOF-103-Na; (D) ICOF-101-Li; (E) ICOF-102-Li; and (F) ICOF-

[0044] 103-Li. (G) Picture showing gram scale (10 g) production of ICOF- 103 -Li.

[0045] Fig. 28A-B. Home build batch adsorption system used for measurement of (A) isotherms for pure components and (B) mixture gas adsorption at a given temperature for ICOFs. Fig. 29. Isotherms for hydrogen measured at different temperatures (25°C, 40°C, 55°C, 70°C, 85°C, 100°C) on ICOF-103-Li. The solid symbols represent the experimental data while the solid lines represent the Langmuir isotherm model fitting.

[0046] Fig. 30. Isotherms for carbon dioxide measured at different temperatures (25°C, 40°C, 55°C, 70°C, 85°C and 100°C) on ICOF-103-Li. The solid symbols represent the experimental data while the solid lines represent the Langmuir isotherm model fitting.

[0047] Fig. 31. Isotherms for oxygen measured at different temperatures (25°C, 40°C, 55°C, 70°C and 75°C) on ICOF-103-Li. The solid symbols represent the experimental data while the solid lines represent the Langmuir isotherm model fitting.

[0048] Fig. 32. Isotherms for nitrogen measured at different temperatures (25°C, 40°C, 45°C, 50°C, 55°C and 70°C) on ICOF-103-Li. The solid symbols represent the experimental data while the solid lines represent the Langmuir isotherm model fitting.

[0049] Fig. 33. Isotherms for methane measured at different temperatures (25°C, 40°C, 45°C, 50°C, 55°C and 70°C) on ICOF-103-Li. The solid symbols represent the experimental data while the solid lines represent the Langmuir isotherm model fitting.

[0050] Fig. 34. Isotherms for hydrogen measured at different temperatures (25°C, 40°C, 55°C and 70°C) on ICOF-103-Na. The solid symbols represent the experimental data while the solid lines represent the Langmuir isotherm model fitting.

[0051] Fig. 35. Isotherms for carbon dioxide measured at different temperatures (25°C, 40°C, 55°C, 65°C, 70°C and 85°C) on ICOF-103-Na. The solid symbols represent the experimental data while the solid lines represent the Langmuir isotherm model fitting.

[0052] Fig. 36. Isotherms for oxygen measured at different temperatures (25°C, 40°C, 45°C, 50°C and 55°C) on ICOF-103-Na. The solid symbols represent the experimental data while the solid lines represent the Langmuir isotherm model fitting.

[0053] Fig. 37. Isotherms for nitrogen measured at different temperatures (25°C, 35°C, 40°C and 55°C) on ICOF-103-Na. The solid symbols represent the experimental data while the solid lines represent the Langmuir isotherm model fitting.

[0054] Fig. 38. Isotherms for methane measured at different temperatures (25°C, 30°C, 35°C, 40°C and 85°C) on ICOF-103-Na. The solid symbols represent the experimental data while the solid lines represent the Langmuir isotherm model fitting. Fig. 39A-B. Molecular cut off for ICOF-103-Li at 3 bar (A) and 5 bars (B). The dashed lines represent the thermodynamically estimated gas uptake at different temperatures based on the isotherms at two lowest temperatures.

[0055] Fig. 40. Layered-structure of ICOF-103-Li as modeled in ab initio molecular dynamics simulation.

[0056] Fig. 41. Change in the accessible iso-surface volume with temperature for ICOF-103-Li. The y-axis represents the iso-surface volume as a percentage of the substructure total volume. H2 and N2 are the two probe molecules used for determining the iso-surface volume. A volume as low as ~1% indicates pores closed for that probe molecule.

[0057] Fig. 42A-B. Oscillation frequency for ICOF linkers is high enough to cut off molecules from entering the pores. (A) Schematic showing the movement of a gas molecule required to enter the pore; the pore being surrounded by 4 linkers which oscillates. (B) Schematic showing the shortest distance a gas molecule needs to travel to enter a pore; in reality a gas molecule needs to traverse orders of magnitude larger distance to enter the pore of a material. (C) Schematic showing the location of the linker during the oscillation - for half of the time period, the linkers are in a position away from the pore mouth. During the time period when linkers are away from the pore mouth, there might be a possibility for the gas molecule to enter the pore. However, 4 such linkers need to be in a position away from the pore mouth. The probability of this happening is (1 / 2) x (1 / 2) x (1 / 2) x (1 / 2) of the time period of oscillation (time period = frequency-1). Applicants calculated the speed of the gas molecules and found out that this period of time is not enough for gas molecules to enter the pores of ICOF. Hence, linker oscillations in ICOF are fast enough to cut off gas molecules.

[0058] Fig. 43. Structural comparison of boroxine, boronate ester, spiroborate and tetraphenoxy borate linkages.

[0059] Fig. 44A-B. Molecular cut off for ICOF-103-Na for 3 bar (top) and 5 bars (bottom). The dashed lines represent the thermodynamically estimated gas uptake at different temperatures based on the isotherms at two lowest temperatures.

[0060] Fig. 45. Distortion of ICOF-Na unit cell. The table presents average alpha, beta, and gamma angles and their standard deviation for the unit cells of ICOF 103 -Li and ICOF 103 -Na from AIMD simulations at 25°C. The standard deviation of alpha and beta angles for ICOF-103-Na are larger compared to ICOF-103-Li, suggesting the unit cell distorts (or deforms) more in ICOF-Na. This distortion may result in smaller pore size of ICOF-103-Na, leading to onset of TRAMS at an earlier temperature compared to ICOF-103-Li.

[0061] Fig. 46A-B. (A) Change of pore size with temperature for ICOF-103-Li and ICOF-103- Na. The aperture adjustment is faster in the initial stage, then it becomes slower. (B) The simulation provides a good prediction of the pore size of ICOF-103-Li. A root mean square error (RSME) of 0.044 indicates a good fit of the model prediction for the experimental data. The initial point for the experimental data for ICOF-103-Li was based on the kinetic diameter of CH4; pore size of ICOF is slightly larger than CH4 molecule as this molecule can easily enter the ICOF.

[0062] Fig. 47. CO2 isotherm measured at 25°C for pristine sample (ICOF-103-Li) compared to the same sample after 30 heating and cooling cycle (with temperatures swinging between 25°C and 100°C).

[0063] Fig. 48. CO2 isotherm measured at 25°C for pristine sample (ICOF-103-Na) compared to the same sample after 30 heating and cooling cycle (with temperatures swinging between 25°C and 100°C).

[0064] Fig. 49. Single heating and colling cycle for ICOF-103-Na. Top: during heating, the amplitude of oscillation increases, causing an increase in the standard deviation of the angle (a > a’) between the two linker at the boron center. This is followed by cooling and decrease in amplitude of the oscillation. Thus, one cycle comprises of skewing of the B-B-B angle and going from one low amplitude oscillation state (at 30°C) to a high amplitude oscillation state (at 100°C) and again back to low amplitude oscillation state (30°C) when temperatures change as depicted in the bottom schematic. Applicants tested its ICOF for 100 such cycles.

[0065] Fig. 50. Powdered X-Ray diffraction (PXRD) pattern for pristine sample, ICOF-103-Li (top) and ICOF-103-Na (bottom) and the sample after 30 heating and cooling cycle.

[0066] Fig. 51. Selectivity and N2 capacity for ICOF-103-Na for potential separation of N2 from CH4.

[0067] Fig. 52. Selectivity and O2 capacity for ICOF-103-Na for potential separation of O2 from N2.

[0068] Fig. 53. Selectivity and N2 capacity for ICOF-103-Li for potential separation of N2 from CH4.

[0069] Fig. 54. Selectivity and O2 capacity for ICOF-103-Li for potential separation of O2 from N2. Fig. 55A-D. Selectivity and Capacity for various gas pairs for (A and B) TCOF-103-Na and (C and D) ICOF-103-Li. For these gas pairs, the smaller gas in the pair, has very high affinity compared to the larger gas in the pair. For such cases, at lower temperatures, before the sieving temperature, there is already a considerable selectivity between the small and larger gas molecules. As the ICOF approaches sieving temperature, the larger gas molecules cannot enter the structure, and it causes a steep 10 fold increase in selectivity. Thus, TRMS also allows for better selectivity for these types of gas pairs, although there is some capacity loss.

[0070] Fig. 56. Adsorbed phase N2 / CH4 selectivity and the N2 capacity calculated from ideal adsorbed solution theory (IAST) using pure gas isotherms. The percentages alongside the data point represent the CF composition in the mixtures.

[0071] Fig. 57. Applicants assume that the starting quadrilateral includes a square where the angle is 90°. When the angle a> increases to m’ due to temperature, the diameter (d’) of the largest circle that can fit in this quadrilateral can be given by the equation shown in the figure.

[0072] DETAILED DESCRIPTION OF THE INVENTION

[0073] The present invention describes a microporous crystalline materials having uniform molecular-sized pores. In a preferred embodiment, the microporous crystalline material can be used in a broad range of applications, such as sensors, catalysis, and separations. However, it is challenging to tune the pore size of a single material continuously and reversibly to distinguish small molecules

[0074] In one aspect, the present invention includes a microporous crystalline material, generally referred to as ionic covalent organic frameworks (ICOFs), having reversible, ultra-high precision pore tunability synthesized by easy-access diol building blocks via simple dynamic borate chemistry. In this preferred embodiment, the meticulous synergy of strong covalent bonds and weaker ion-dipole interactions in the ICOFs allow resolution (< 0.2 A) for micropore adjustment over a pore size range of 2.9 to 4.0A upon a temperature change from approximately 25 to 95°C. This precise temperature-dependent pore shrinkage was controlled by the fast local linker oscillation, whose amplitude changes with temperature to adjust the pores in ICOFs. Moreover, ICOFs of the invention showed structural robustness (up to at least 100 thermal cycles), while maintaining precise, reversible pore tunability. Record-high selectivity for difficult-to-separate, industrially important gas pairs, O2 / N2 and N2 / CH4, was observed. Such precision in continuous, reversible pore tunability within a sub-A scale via TRMS allow new and more effective uses of microporous crystalline materials in different fields.

[0075] The present invention includes a novel microporous crystalline lattice composition comprising a plurality of chemical subunits bound by a series of cross-linked covalent tetraphenoxy borate linkages and weak ion-dipole interactions forming an ionic covalent organic framework (ICOF) having a plurality of tunable iso-surface channels. In one preferred embodiment, the chemical subunits of the invention can be selected from, and include one or more the compounds according to Formulas I-III:

[0076] In this embodiment, X+is a metal ion, preferably selected from Li+or Na+. As shown in the figures generally, the chemical subunits can form a microporous crystalline lattice structure. In this embodiment, the lattice structure is formed by crosslinking the chemical submunites of the invention in an xy plane by a strong covalent tetraphenborate bonds between the oxygen (O) and boron (B) atoms of the chemical subunits, and in a y plane through the weak ion-dipole interaction between the O of the chemical subunits and the metal ion, which as described above can include Li+orNa+.

[0077] The microporous crystalline lattice structure as generally described above includes a plurality of tunable iso-surface channels. In a referred embodiment, the iso-surface channels are continuously and reversibly tunable via changes in temperature. As described in the Examples below, the iso-surface channels of the invention are continuously and reversibly tunable between approximately 2.9 to 4.0 A, with resolution at or below 0.2 A. Due to this continuous and reversible thermal-tuning, the iso-surface channels of the invention can be tuned to selectively adsorb a gas compound via thermo-regulatory molecular sieving (TRMS). In one example of TRSM, the isosurface channels of the invention can be thermally tuned to selectively adsorb a gas from a complex mixture of gasses based on the size of the target gas to be isolated. Examples of complex gas mixtures can include, but not be limited to mixtures of H2, CO2, O2, N2 and CH4. among others.

[0078] The invention further includes methods of synthesizing a microporous crystalline lattice composition. In a preferred embodiment, a diol linker, and preferably an aryl diol having an aromatic group, is contacted with a borohydride salt, such as sodium borohydride or lithium borohydride, under conditions sufficient to produce a condensation reaction forming a chemical subunit, wherein the chemical subunit is configured to be crosslinked forming an ionic covalent organic framework (ICOF) having a plurality of tunable iso-surface channels.

[0079] In one embodiment, the diol linker of the invention includes hydroquinone and generates a chemical subunit according to Formula III:

[0080] In this embodiment, X1is a metal ion, preferably selected from Li1or Na1.

[0081] In another embodiment, the diol linker of the invention includes 2,6-dihydroxynaphthalene and generates a chemical subunit according to Formula II: In this embodiment, X+is a metal ion, preferably selected from Li+or Na

[0082] In another embodiment, the diol linker of the invention includes 4,4'-biphenol and generates a chemical subunit according to Formula I:

[0083] X+, (Formula I)

[0084] In this embodiment, X+is a metal ion, preferably selected from Li+or Nat

[0085] As noted above, any of the above chemical subunits can form a microporous crystalline lattice structures wherein one or more of the subunits are crosslinked by a series of cross-linked covalent tetraphenoxyb orate linkages and weak ion-dipole interactions forming the ICOF having a plurality of continuously and reversibly tunable iso-surface channels as generally described herein.

[0086] The present invention further includes systems, methods and compositions for separating a complex gas mixture. In a preferred embodiment, the method includes contacting a complex gas mixture containing at least two different gases with a microporous crystalline lattice composition comprising a series of chemical subunits bound by a series of cross-linked covalent tetraphenoxyborate linkages and weak ion-dipole interactions forming an ionic covalent organic framework (ICOF) having a plurality of tunable iso-surface channels as generally described above. The temperature of the ICOF compositions is adjusted to tune the iso-surface channels so as to selectively adsorb at least one gas of the complex mixture, this process being generally referred to herein as thermo-regulatory molecular sieving (TRMS), which as shown below demonstrates continuous and reversible unable iso-surface channels are continuously tunability of the isochannels of the invention between approximately 2.9 to 4.0 A, with resolution at or below 0.2 A. Examples of complex gas mixtures can include, but not be limited to mixtures of H2, CO2, O2, N2 and CH4, among others.

[0087] As used herein, “crystalline ionic covalent organic frameworks” or ICOFs, means microporous crystalline lattice structures containing, preferably tetraphenoxyb orate linkages to synthesize a series of ionic covalent organic frameworks having thermodynamic pores to achieve continuous and reversible tunability between 2.9 to 4.0 A, with resolution below 0.2 A, resulting from gradual amplitude change of linker oscillation regulated by temperature.

[0088] As used herein, ‘thermo-regulatory molecular sieving’ or TRMS, means modulating the temperature of thermoelastic apertures of ICOFs selectively block larger molecules over marginally smaller ones, demonstrating size-based molecular recognition, which can allow separation of complex mixtures, and in particular complex gas mixtures, such as O2 / N2 and N2 / CH4, with high adsorptive selectivity.

[0089] As used herein, a “complex mixture” means a mixture containing at least two gas compositions.

[0090] As used herein, a “diol” refers to a compound comprising two hydroxyl (OH) functional groups. The term "aromatic diol" means any aromatic or predominantly aromatic compound having at least two associated hydroxyl substitutions. In certain embodiments, the aromatic diol may have two or more phenolic hydroxyl groups.

[0091] As used herein, the term “condensation ” or “condensation reaction” means a chemical reaction, in which the functional groups of two reagents react to form one single molecule, i.e., the reaction product, and a low molecular weight molecule, for example water, is released.

[0092] The term “aryl” or “aromatic moiety” as used herein refers to an aromatic ring system, which may further include one or more non-carbon atoms. These are typically 5-6 membered isolated rings, or 8-10 membered bicyclic groups, and can be substituted. Thus, contemplated aryl groups include (e.g., phenyl, naphthyl, etc.) and pyridyl. Further contemplated aryl groups may be fused (i.e., covalently bound with 2 atoms on the first aromatic ring) with one or two 5- or 6- membered aryl or heterocyclic group and are thus termed “fused aryl” or “fused aromatic”.

[0093] Aromatic groups containing one or more heteroatoms (typically N, O or S) as ring members can be referred to as heteroaryl or heteroaromatic groups. Typical heteroaromatic groups include monocyclic C5-C6 aromatic groups such as pyridyl, pyrimidyl, pyrazinyl, thienyl, furanyl, pyrrolyl, pyrazolyl, thiazolyl, oxazolyl, isothiazolyl, isoxazolyl, and imidazolyl and the fused bicyclic moieties formed by fusing one of these monocyclic groups with a phenyl ring or with any of the heteroaromatic monocyclic groups to form a C8-C10 bicyclic group such as indolyl, benzimidazolyl, indazolyl, benzotriazolyl, isoquinolyl, quinolyl, benzothiazolyl, benzofuranyl, pyrazolopyridyl, pyrazolopy rimidyl, quinazolinyl, quinoxalinyl, cinnolinyl, and the like. Any monocyclic or fused ring bicyclic system which has the characteristics of aromaticity in terms of electron distribution throughout the ring system is included in this definition. It also includes bicyclic groups where at least the ring which is directly attached to the remainder of the molecule has the characteristics of aromaticity. Typically, the ring systems contain 5-12 ring member atoms.

[0094] As also used herein, the terms “heterocycle”, “cycloheteroalkyl”, and “heterocyclic moi eties” are used interchangeably herein and refer to any compound in which a plurality of atoms form a ring via a plurality of covalent bonds, wherein the ring includes at least one atom other than a carbon atom as a ring member. Particularly contemplated heterocyclic rings include 5- and 6- membered rings with nitrogen, sulfur, or oxygen as the non-carbon atom (e.g., imidazole, pyrrole, triazole, dihydropyrimidine, indole, pyridine, thiazole, tetrazole etc.). Typically, these rings contain 0-1 oxygen or sulfur atoms, at least one and typically 2-3 carbon atoms, and up to four nitrogen atoms as ring members. Further contemplated heterocycles may be fused (i.e., covalently bound with two atoms on the first heterocyclic ring) to one or two carbocyclic rings or heterocycles and are thus termed “fused heterocycle” or “fused heterocyclic ring” or “fused heterocyclic moi eties” as used herein. Where the ring is aromatic, these can be referred to herein as ‘heteroaryl’ or heteroaromatic groups.

[0095] Heterocyclic groups that are not aromatic can be substituted with groups suitable for alkyl group substituents, as set forth above.

[0096] Aryl and heteroaryl groups can be substituted where permitted. Suitable substituents include, but are not limited to, halo, — ORa, — NRa2, — SRa, — SChRa, — SChNRa2, — NRaSO2Ra, — NRaCONRa2, — NRaCOORa, — NRaCORa, — CN, — COORa, — CONRa2, — OOCRa, — CORa, and — NO2, wherein each Rais independently H, C1-C8 alkyl, C2-C8 heteroalkyl, C3-C8 heterocyclyl, C4-C10 heterocyclyclalkyl, C1-C8 acyl, C2-C8 heteroacyl, C2-C8 alkenyl, C2-C8 heteroalkenyl, C2-C8 alkynyl, C2-C8 heteroalkynyl, C6-C10 aryl, or C5-C10 heteroaryl, and each Rais optionally substituted with halo, =0, =N — CN, =N — ORb, — N — Rb, ORb, NRb2, SRb, SO2Rb, SO2NRb2, NRbS02Rb, NRbC0NRb2, NRbC00Rb, NRbC0Rb, CN, C00Rb, C0NRb2, 00CRb, C0Rb, and NO2, wherein each Rbis independently H, C1-C8 alkyl, C2-C8 heteroalkyl, C3-C8 heterocyclyl, C4-C10 heterocyclyclalkyl, C1-C8 acyl, C2-C8 heteroacyl, C6-C10 aryl or C5-C10 heteroaryl. Alkyl, alkenyl and alkynyl groups can also be substituted by C1-C8 acyl, C2- C8 heteroacyl, C6-C10 aryl or C5-C10 heteroaryl, each of which can be substituted by the substituents that are appropriate for the particular group. Where a substituent group contains two Raor Rbgroups on the same or adjacent atoms (e.g., — NRb2, or NRb— C(O)Rb), the two Raor Rbgroups can optionally be taken together with the atoms in the substituent group to which are attached to form a ring having 5-8 ring members, which can be substituted as allowed for the Raor Rbitself, and can contain an additional heteroatom (N, O or S) as a ring member.

[0097] The invention now being generally described will be more readily understood by reference to the following examples, which are included merely for the purposes of illustration of certain embodiments of the embodiments of the present invention. The examples are not intended to limit the invention, as one of skill in the art would recognize from the above teachings and the following examples that other techniques and methods can satisfy the claims and can be employed without departing from the scope of the claimed invention. Indeed, while this invention has been particularly shown and described with references to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the invention encompassed by the appended claims.

[0098] EXAMPLES

[0099] Example 1 : Synthesis of ICQFs.

[0100] To synthesize these ICOFs, Applicants started with the simplest building blocks, hydroquinone (1) and sodium borohydride as shown in Fig. 1A, where Aryl is phenyl and M is Na. The 1 :2 stoichiometric mixture of sodium borohydride and hydroquinone was heated at 120°C in acetonitrile without any disturbance to yield the ICOF-101-Na with an isolated yield of 81%. The infrared (IR) spectrum of ICOF-101-Na shows the absence of O-H stretching at 3,300 cm-1 and B-H stretching at 2,300 cm-1 and the presence of B-0 stretching band at 950 cm-1 (Fig. IB). The overall IR spectrum of the ICOF-101-Na closely resembles that of the NaTB (Sodium Tetraphenxoxyb orate, a model compound with tetraphenoxyborate linkage), supporting the formation of [BO4]- anions (31). The chemical structure of ICOF-101-Na was further confirmed by solid-state 1 IB and 13C nuclear magnetic resonance (NMR) spectroscopy (Fig. 1C, figs. 5-6). In the solid-state 11B NMR spectrum, a characteristic signal corresponding to tetra- substituted boron was observed at 2.06 ppm, which is consistent with the boron resonance signal observed for NaTB, suggesting the formation tetraphenoxyborate linkage. The single resonance in the 1 IB NMR spectrum of ICOF-101-Na indicated negligible defect sites within the frameworks. Additionally, two sharp signals observed at 120 ppm and 150 ppm in the 13C NMR spectrum also support the highly symmetrical chemical environment in ICOF-101-Na (fig. 5). The powder X-ray diffraction (PXRD) pattern at room temperature confirmed the crystallinity of ICOF-101-Na with no observable diffraction peaks from the starting materials, hydroquinone, or sodium borohydride (Fig. ID). For a tetrahedral-shaped node-based extended structure, dia topology is commonly observed or adopted, irrespective of connection types and linkers (32, 33). Thus, Applicants first modeled the framework using tetraphenoxyborate linkage as tetrahedral nodes in dia topology and assumed free positioning of the sodium counterion. However, none of these generated models, including various interpenetration folds, matched the experimental PXRD pattern, suggesting the sodium ion may interfere with the solid-state structure of the framework (fig. 7, table SI).

[0101] Inspired by the crystal structure of the NaTB, where the sodium ion is weakly bound with tetraphenoxy borate linkage (3 / ), Applicants built a layered 2-dimensional (2D) structure for ICOF-101-Na in a space group of P4 / N, where the tetrahedral nodes propagate in the same plane. The unit cell parameters (a = b = 10.6850 A, c = 5.7690 A, a = P = y = 90°) were obtained and further refined with Pawlay fitting which showed a good agreement factor with experimental PXRD diffraction (Rp = 1.27% and Rwp = 2.07%, Fig. ID, Table S2). In Applicants modeled structure, four phenyl groups were joined together by strong covalent tetraphenoxyb orate linkage and further extended in the planar direction (Fig. IE). In Fig. ID, (110) facet on PXRD validated the square repeating unit cell that is connected by four hydroquinone via the strong tetraphenoxylborate linkage. More importantly, Applicants verified the presence of the weak iondipole interaction between oxygen and metal ion along the z axis by observing the (001) peak at 15.10°. The sodium counterions are bridged by four oxygen atoms of borate anions from the adjacent layers, forming an alternating organic cationic and metal ion layer in a 2D layered structure. To validate the layered model, Applicants calculated interlayer distance using the Na-0 distance from the single crystal structure of NaTB and found it matched very well with the tZ( 100) spacing (5.9 A) observed in the PXRD pattern of ICOF-101-Na. Applicants also performed variable temperature PXRD experiments over a range of 25 to 200°C and detected no significant peak shifts (fig. 8), demonstrating the thermal stability of the crystalline structure.

[0102] Example 2: Isoreticular expansion of ICOFs.

[0103] After demonstrating the feasibility of tetraphenoxyborate chemistry to construct a crystalline ICOF, further advanced the versatility of this approach through isoreticular expansion of ICOF-101-Na in both horizontal direction by introducing the expanded linkers of 2,6- dihydroxynaphthalene (2) and 4,4’-biphenol (3), and vertical direction by intercalating the lithium- ion as shown in Fig. 1A. The corresponding ICOFs (five additional ICOFs from ICOF-102-Na to ICOF-103-Li) were synthesized and characterized in the same fashion as ICOF-101-Na (figs. 9- 27, table S2-S9); they followed the expected pattern of isoreticulation and exhibited similar spectroscopic and PXRD patterns (Fig. IF). In particular, a gradual shift of the lowest angle diffraction peak corresponding to the (110) facet was observed from ICOF-101 to ICOF-103 series, which agrees with the increased linker lengths of phenyl, naphthyl, and biphenyl and thus the increased size of the pore channels. Notably, all Na-series ICOFs exhibited a 20 peak at around 15.0° on the (001) facet, indicating the interlayer distance generated by the coordination of sodium ions between two anion layers. Conversely, all Li-series ICOFs exhibited a (001) facet peak at around 17.5°, which was shifted by 2.5° from Na-series, owing to the shorter Li-0 distance and resulting shorter interlayer distance. Applicants also demonstrated facile synthesis of ICOF on a 10-g scale (fig. 27g). Taken together, Applicants demonstrate a versatile synthetic strategy to construct ICOFs with building blocks of different lengths, providing a powerful platform to generate highly precise and tunable aperture size upon temperature change.

[0104] Example 3: Chemical Characteristics of ICOFs.

[0105] Crystalline microporous materials are promising for gas storage and separation (8, 13, 19). Given the porous nature of the ICOF structures, Applicants investigated the gas adsorption behavior under thermodynamic equilibrium condition for ICOF-103-Na and ICOF-103-Li, which have the highest crystallinity among all the synthesized ICOFs. A home-built, well calibrated, volumetric gas adsorption system (fig. 28) was used to measure adsorption isotherms up to 7 bar (figs. 29-38) for different gases (H2, CO2, O2, N2 and CH4; properties in table S10) having kinetic diameter between 2.89 and 3.80 A, with miniscule (< 0.2 A) differences in their sizes (34, 35).

[0106] At 25°C, ICOF-103-Li adsorbs N2 and CH4 (Fig. 2A-I), indicating both largest molecules can easily access the pores. Uptake of larger CH4 molecule is significantly higher than N2 (ideal selectivity of CH4 / N2 = 4.96 at 1 bar), resulting from its octupole moment and thus stronger affinity (36). However, when Applicants measured isotherms at 50°C (Fig. 2A-II), surprisingly, CH4 uptake decreased ~85 times, while N2 uptake decreased only 1.8 times, leading to reversed, sizedependent selectivity of N2 over CH4 (ideal selectivity of N2 / CH4: ~10 at 1 bar). Thus, CH4 faces difficulty in accessing pores of ICOF-103-Li, whereas N2 (only 0.16 A smaller) can still easily enter. Applicants suspect this significant decrease of gas uptake of larger molecules may be attributed to change in the effective pore size of TCOF-103-Li resulting from temperature change. To further investigate this potential pore shrinkage due to temperature, Applicants measured gas uptake at 55°C and found N2 molecules being effectively blocked by ICOF pores at this temperature. However, O2 molecules (-0.18 A smaller) can access the pores and be adsorbed (Fig. 2A-III), probably suggesting further pore shrinkage. At 70°C, O2 exhibited negligible uptake, whereas CO2 (-0.16 A smaller) was readily adsorbed (Fig. 2A-IV). At 100°C, the effective pore size seemed to have become so small that even CO2 was blocked, allowing only the smallest molecule, H2 (2.89 A), to access the pores (Fig. 2A-V). Applicants thus hypothesize that the pores in ICOF-103-Li continuously shrink due to temperature change from 25 to 100°C and thus a desired pore size might be obtained at a specific temperature, as shown in Fig. 2A (top). This might offer the opportunity for size-based adsorptive separation of gas molecules simply by adjusting the temperature.

[0107] This decrease in gas uptake with temperature might also be due to the exothermic nature of adsorption, which reduces gas uptake at higher temperature (37-39). Applicants calculated the expected uptake for the gases at different temperatures based on their measured adsorption isotherms at the lowest temperatures. This would allow us to estimate the uptake values at different temperatures, assuming the porous materials would maintain the same structure and surface properties over the temperature range. Fig. 2B (top) shows the measured uptake of the five gas molecules at 1 bar (points and solid lines), normalized by CO2 uptake at 1 bar and room temperature, for a temperature range of 25-100°C for ICOF-103-Li; dashed lines represent calculated uptakes at different temperatures. A large deviation, 1-2 orders of magnitude, between the measured uptakes and the calculated uptakes at a specific temperature was observed for all the molecules, except H2. The drastic capacity drop occurred at lower temperatures for larger molecules, with CH4 at 50°C, N2 at 55°C, O2 at 70°C, and CO2 at 95°C. Apparently, temperature effect on gas uptake cannot exclusively explain this large deviation, and temperature dependent pore shrinkage might be the dominant reason, as Applicants hypothesized above. Similar behavior was also observed at higher pressures for ICOF-103-Li (fig. 39). Kinetic diameter of these gases suggests that the pores of ICOF-103-Li be precisely tuned between 2.9 and 3.8 A by regulating temperature between 50°C and 95°C. Surprisingly, Applicants observed no structural changes at different temperatures from 30°C to 200°C in PXRD (fig. 8), suggesting transient local molecular motions could be responsible for the pore size change (J 8). Aperture change in ICOF-103-Li upon temperature change was investigated by ab initio molecular dynamics (AIMD) simulations. ICOF-103-Li was modeled based on the crystal structure obtained from its PXRD pattern (Fig. 3A). As expected, ICOF-103-Li has a layered structure in the xy plane with pores in the z direction (Fig. 3 A left, fig. 49). Each layer is comprised of quadrilateral substructures in the xy plane (Fig. 3A, right) having channels (or pores) along z- axis. The iso-surface channel in the middle of these substructures indicates the volume available for gas adsorption, diameter of which at 25° C is of the order of small gas molecules (Fig. 3A, right). Applicants’ simulation indicates negligible variation in bond lengths within simulation timescale (table Si l). However, transient oscillatory motion of the quadrilateral substructure was observed (Fig. 3B). This oscillation was monitored by B-B-B bridge angle (m) in xy plane, which was computed from AIMD simulation trajectories (table S 12). Due to this oscillation, the angle swung around an initial position, and Applicants defined maximum and minimal angle as omax and (nmin, respectively (Fig. 3B). As temperature increases, the amplitude of the oscillation increases continuously, which caused larger differences between ( min and (nmax at higher temperatures (Fig. 3C). This manifests in continuous shrinking of the ICOF pores with temperature, coherent with Applicants gas adsorption results. Temperature change also marginally distorts the substructure. Applicants’ theoretical calculation shows pore size tunability to be within the range of the miniscule size differences of gas molecules (Fig. 3D). Consistently, the increase of vibrational amplitude with temperature reduces the iso-surface volume (Fig. 41) indicating pore size reduction. For dynamic pores whose sizes are determined by oscillation of linkers at the pore mouth, the high oscillation frequency might be essential for preventing approaching gas molecules from entering the pores. Oscillation frequency in ICOFs is calculated to be in the order of 1013 s- 1, similar to the reported values of some zeolitic imidazolate frameworks (40, 41). At such high frequencies, the time period when the dynamic pores are open to a molecule during an oscillation might be inadequate for it to enter the pores (fig. 42, table SI 3). Thus, during oscillation the smallest aperture size (regulated by amplitude change via temperature) determines the effective pore size. This realizes ultra-high precision tunability via temperature adjustment, allowing sizedependent molecular recognition with resolution below 0.2 A.

[0108] This unique local molecular movement manifests from the synergistic effect of strong covalent bonds and weaker ion-dipole interactions, providing long range order as well as local flexibility. Flexibility required to enable such pore size change can be attributed to the rational material design. Applicants reasoned such local flexibility to tetraphenoxyborate linkages, which permitted relatively free movement of linkers (fig. 43), in strong contrast to more common cases of borate chemistry, where catechol derivatives are reacted with boric acid (28, 42). Applicants design permits local flexibility, allowing precise, continuous adjustment of the amplitude of high frequency oscillation of linkers via temperature adjustment. This enables reversible, dynamic pore size change in ICOFs, realizing size-dependent molecular recognition with an unprecedented resolution below 0.2 A. Thus, temperature (or heat) adjusts ICOF pores, leading to the disruption of typical gas uptake behavior. For example, by simply changing temperature from 25 to 50°C, the ICOF-103-Li pores allow entry of N2, while it effectively blocks slightly larger CF molecules. Applicants call this temperature dependent, size-based molecular recognition as ‘thermoregulatory molecular sieving’ (TRMS). TRMS is so precise that by just adjusting temperature, Applicants can alter the pore sizes of ICOF-103-Li within the sub-A range with <0.2 A resolution. Applicants’ simulation indicates that TRMS enables continuous pore adjustment in ICOFs, rather than a few limited discreate states with different pore sizes. Thus, pore adjustment within sub-A range manifested by TRMS should allow high selectivity between gas molecules with tiny size differences.

[0109] In ICOF-103-Na, similar pore adjustment via TRMS was observed at 1 bar (Fig. 2B, bottom) and also at higher pressures (fig. 44; for 3 and 5 bar) between 35 to 70°C. The temperature range for TRMS for ICOF-103-Li and its Na counterpart differs possibly because of the slightly distorted framework of ICOF-103-Na (fig. 45). This results in ‘pore shrinking’ at lower temperatures compared to ICOF-103-Li. Nevertheless, TRMS continuously adjusts ICOF pores to effectively recognize gas molecules based on their < 0.2 A size difference (Fig. 2C). The pore size change is not linearly decreasing with the temperature stimuli. Initially it decreases faster, followed by a much slower change at higher temperatures. This trend is similar to the change of pore size calculated from Applicants AIMD simulation (Fig. 3D and fig. 46). Applicants expect to attain any desired pore size between the sizes of H2 and CFU molecules via careful temperature control (Fig. 2C, schematic). To the best of Applicants knowledge, this represents the most precise tunability among all reported flexible crystalline materials specifically targeting molecular recognition (48, 23-25).

[0110] For materials with such dynamic motion, concern remains for them to undergo irreversible structural changes during repeated back-and-forth motion (43). It is challenging to maintain full reversibility for such materials (43). To examine this, Applicants re-measured CO2 adsorption isotherm at 25°C after 30 heating-cooling cycles (between 25 and 100°C, figs. 47-48) and found no obvious change in the adsorption behavior (tables S14-15) for ICOFs. Applicants further subjected ICOF-103-Na to cyclic temperature swing between 30°C and 100°C for over 100 cycles and gravimetrically measured the change in CO2 uptake (Fig. 2D). Applicants observed consistent CO2 uptake (<1% variation) for ICOF-103-Na for 100 cycles; where each cycle involves change from the lower amplitude oscillation state to the highest amplitude oscillation state at two extreme temperatures (Fig. 2D, inset and fig. 49). PXRD patterns for ICOFs before and after 30 aggressive heating-cooling cycles also showed no differences (fig. 50), suggesting no obvious structural change. Applicants speculate that the relatively weak ion-dipole interaction allows flexibility while strong covalent bond guarantees structural integrity, realizing complete reversibility even after 100 cycles. In all, Applicants results indicate reversible dynamic robustness of ICOFs under repeated back-and-forth motion of the framework.

[0111] Microporous crystalline materials having such precisely tunable, robust and reversible pores are ideal for adsorptive separation of molecules with almost indistinguishable size / shape differences, such as O2 / N2 and N2 / CH4 (79, 24). Fig. 4 shows the transition of the adsorption behavior of ICOF-103-Li and ICOF-103-Na for industrially relevant gas pairs and their adsorptive performance comparison for two challenging gas pairs, O2 / N2 and N2 / CH4, with reported microporous materials. Applicants observed affinity-driven selectivity at 25°C. For example, CH4 uptake is higher than N2, resulting in N2 / CH4 selectivity below 1 at all pressures. This is similar to that observed in most reported materials (table S16). However, at “sieving temperature” (temperature for transition from affinity to size-based selectivity, 70°C for ICOF-103-Li and 35°C for ICOF103-Na), TRMS enables size-based sieving, leading to N2 / CH4 selectivity as high as 45 for ICOF-103-Na (and 13.5 for ICOF-103-Li) at 7 bar pressure (Fig. 4A-I and B-I). TRMS is accompanied by some capacity loss. However, achieving this size-based, “reverse selectivity” is extremely challenging and has significant energy savings benefits ( ); as in the case of N2 removal from natural gas. ICOFs at “sieving temperature” show increase of both selectivity and capacity for the smaller gases with pressure increase, showing promising for high pressure applications; for example, N2 / CH4 mixtures in natural gas well are typically at 100-300 bar. The transition from affinity-based selectivity to size-based selectivity is also evident for other gas pairs (O2 / N2 and H2 / CO2) for ICOF-103-Li / Na, where TRMS yields size-based selectivity at sieving temperatures labelled in Fig. 4A and B. Thus, by only adjusting the temperature, TCOFs, via their unique TRMS mechanism, exhibit tremendous potential for separating industrially important gas mixtures (Fig. 4A and B), including challenging pairs, such as O2 / N2 and N2 / CH4 (figs. 50-55).

[0112] The unique TRMS mechanism of ICOFs enables them to accurately differentiate molecules within the size range of 3-4 A, with size difference < 0.2 A. This exceptional capability results in unprecedented adsorptive selectivity for challenging gas mixtures, such as N2 / CH4 and O2 / N2 (Fig. 4C and D, table S16-17). The size-dependent selectivity at 50°C was confirmed for N2 / CH4 gas mixtures as well (table SI 8), and it is similar to the selectivity calculated using ideal adsorbed solution theory (fig. 56). These results surpass the performance of current state-of-the-art materials reported in the literature. At 1 bar, both ICOF-103-Na and ICOF-103-Li exhibit higher N2 / CH4 selectivity than most reported sorbents, with ICOF-103-Na having a selectivity of 28.8, which is ~5 times higher than the highest reported value (Fig. 4C). As higher pressure favors both capacity and selectivity for ICOFs, Applicants observed higher selectivity at 7 bar. In general, ICOF-103- Li provides higher capacity than ICOF-103-Na, albeit achieving lower selectivity. ICOFs via TRMS achieved record high N2 / CH4 selectivity of 45 at 7 bars (Fig. 4C, ICOF-103-Na). Even for O2 / N2, at 7 bars, a selectivity of ~20 was obtained (Fig. 4D, ICOF-103-Na), surpassing the reported materials.

[0113] Example 4: Estimation of gas uptake of the adsorbent under conditions where its pores remain unchanged.

[0114] It should be noted that temperature plays an important role in adsorption of gases; at higher temperatures, the gas adsorption is usually lower than that at lower temperatures (58, 59). For example, 13X zeolite is a common adsorbent for CO2 adsorption, which is known to have a rigid structure that remains unchanged with external stimuli. For 13X zeolite, it is seen that the temperature determines the gas uptake and with increase in temperature at which adsorption is carried out, the adsorbed amount decreases (58-60). Similar trend is observed on other materials as well (67). In Applicants case, for ICOF, however, the lowering of gas uptakes is also due to the alteration of shape / size of the pores via rotation of the linker rings. Applicants observe sudden drop (~ 1 to 2 orders of magnitude drop) in gas uptake at certain temperatures (different for different temperatures, based on the size of the gas molecules). However, it is important to distinguish the two causes for the drop of uptake. One best way to do this is to thermodynamically estimate the isotherms for a given gas at different temperature based on two isotherms at the lowest temperature. In Applicants case, Applicants choose the first two isotherms at 25°C and 40°C, except for some cases where Applicants have isotherms available at 25°C and 30°C, for example CH4 adsorption onto ICOF-103-Na. Applicants fit the isotherms at the two lowest temperatures using Langmuir’s model (Eq. 1 below).

[0115] Where qe and qe,max is the uptake at give pressure, P and the maximum uptake and KL is the Langmuir isotherm constant. Langmuir model was the best fit for all cases at lowest temperatures. The isotherm coefficient obtained from Langmuir fitting; KL is related to temperature via Arrhenius equation as follows:

[0116] Where KL,0 and E are the constants and T is the temperature at which the KL is measured. Thus, using equation (2) for KL values obtained from equation (1) for isotherms at the lowest temperature allows us to obtain the value of the constant E and KL,0 for equation (2). This allows predicting the KL values for isotherms for any given temperatures.

[0117] Applicants goal is to find the Langmuir model parameters at a given temperature so that Applicants can predict the isotherm at that temperature. Applicants can obtain KL values at different temperatures using equations (1) and (2). Now Applicants need Qmax value for the Langmuir model at different temperatures to estimate the isotherm at those temperatures. Applicants use the Clapeyron-Clausius equation (equation 3) to calculate the heat of adsorption for the given adsorbent for a known gas using the isotherm at the lowest two temperatures.

[0118] Where Pl and P2 are the two pressures from the isotherms measured at temperatures T1 and T2 for the same gas loading value, AH is the heat of adsorption and R is the universal gas constant.

[0119] Essentially, AH is proportional to the slope of P vs T curves for given qe. Ideally the value of heat of adsorption remains the same at all temperatures, given there is no change in the adsorbent. So, for example, if Applicants calculate the AH using isotherms at 25°C and 40°C, this should equate to the AH value obtained from isotherms at 25°C and 70°C. Using this logic, Applicants can compute the qe for the given P and T by equating the slopes. Knowing the qe, P and KL at a given temperature T allows us to compute the value of qe,max for the isotherm at temperature T3. Thus, Applicants can easily construct the isotherm at the new temperature T. It is essential to note that even for the lowest temperature isotherms, there is indeed some effect of capacity drop because of size change. Hence, the thermodynamically estimated uptake drops are the maximum possible drop if the adsorbent remains constant.

[0120] Example 5: Theoretically pore size change due to temperature is in order of difference in gas molecule size.

[0121] The angle at the B-B-B (co, the angle between 3 boron atom in the xy plane) can be used to track the oscillation of the linkers in the ICOF substructure. The oscillation causes the angle co to swing around its initial position from its maximum and minimum values of comax and cumin respectively; Applicants defined comax and comin based on 95% of the distribution of the possible oscillation positions (table SI 2). With the increase in temperature, the oscillation amplitude increases, causing the range of angle co (i.e., c max - comm) increases (table S12). Temperature also causes slight distortion of the quadrilateral substructure. Tracking these two change, Applicants can calculate the total angular changes; the upper bound of the values in Fig. 3C was calculated and used to determine the pore size. Applicants AIMD simulation suggests that there is almost no change in the bond lengths. Thus, Applicants can assume constant length (L) of the quadrilateral. Within this quadrilateral, a circle with the maximum diameter (d) can be fit in. For ease of explanation, let us assume that the starting quadrilateral is the most regular one, a square where the angle co is 90°. When the angle co increases to co’ due to temperature, the diameter (d’) of the largest circle that can fit in this quadrilateral can be given by the equation shown in Fig. 57

[0122] As shown in Fig. 57. the d' is less than d and the difference between them at different temperatures is used to calculate the pore size of ICOF-103-Li. From Applicants calculation, the difference is in the order of difference of sizes of gas molecules. This suggests that the temperature change can tune the pore sizes with very high precision so as to reject small gas molecules based on their sizes. However, the actual pore within the substructure available for gas adsorption is much smaller than the largest circle Applicants can fit in it. This actual pore is estimated by the iso-surface, and it can be argued that if the diameter of the largest circle changes in the sub- A range with temperature, the iso-surface would also change in a similar order. Moreover, from gas adsorption, at 25°C, the ICOF-103-Li allows entry of CH4 molecules into its pores. Thus, Applicants can estimate the pore size at this temperature to be larger than 3.80 A. Based on this pore size, Applicants calculated the pore size of ICOF-103-Li at different temperatures (Fig. 3D). To estimate how well Applicants model fits with the actual experimental data, Applicants calculated the root mean square deviation (RMSE) using the following formula (Eq. 2 below)

[0123] A low RMSD value of 0.044 obtained for Applicants model indicates that it’s a good fit and that the model predicts the experimental data very well (fig. 46).

[0124] Example 6: Oscillation Frequency is higher than gas molecules movement.

[0125] The velocity of the gas molecule can is estimated from classical thermodynamics using the following expression:

[0126] Where VRMS is the average velocity (or root mean square velocity) of gas molecule having a mass of m (in kg) at an absolute temperature of T (K) and k is the Boltzmann constant (1.380x10-23 m2 kg s-2 K-l).

[0127] For example, N2 molecules are at room temperature (i.e., 298.15 K or 25°C). The atomic mass of N2 is 28.02 atomic mass unit (amu), which is equivalent to 4.651 x 10-26 kg (1 amu = 1.66x10-27 kg). This gives the speed of N2 at room temperature as roughly 517 m s-1.

[0128] The frequency of oscillation of the linkers in ICOF-103-Li is 0.61 ps-1 at room temperature (298.15 K or 25°C), as computed from Applicants MD simulation. This is close to values reported for ZIFs (47), but slightly lower than other MOFS (62). Measuring such low molecular vibration is challenging (40, 62). This means that to complete one oscillation (one complete to-and-fro motion), it takes 1.63 ps. Within this time, the N2 molecule moves by a distance of 8.42x 10-10 m or 8.42 A. However, for a gas molecule to enter the pores / channel of ICOF, it needs to move more than its molecular size (size of its molecule + the thickness of the linker) during the time when all four the linker oscillation is away from the pore (Fig. 42). Applicants can make an overestimated assumption that the probability of the all the linkers being away from the center of the pore during the oscillation time period is at most 1 / 4th of the total time period, i.e., 0.4075 ps. Within this time, the N2 molecule can move 2.015 A, which is -57% of the length of the molecule (less than what is needed to enter the pore). Hence N2 molecules can never enter the pore under such high frequency of linker oscillation. In table S13, Applicants calculated and listed the speed of different gas molecules, the given time period of oscillation, the distance the gas molecule moves within the time it gets to enter the pores of ICOF.

[0129] Example 7: Materials and Methods.

[0130] Chemicals and Materials

[0131] All the chemicals were purchased from Aldrich Chemical Co. and used without further purification. Acetonitrile was further dried with 3 molecule sieves for at least 24 hours. Sodium tetraphenoxy borate (NaTB) was synthesized and crystallized according to the literature (37). All reactions were conducted under inert atmosphere (Nitrogen). Gases used for gas adsorption (H2, CO2, 02, N2 and CH4) were purchased from Airgas and were of 99.99% purity. All fittings used to prepare the batch absorption system were procured from Swagelok. The pressure change was measured using a Swagelok E model transducer (0.0-100.0 psia). A Glas-Col 25 ml Micro Mantle (model: 100A MIC25) was used along with a home built heating controller to maintain the sample temperature during the adsorption isotherm measurements.

[0132] Synthetic Procedures

[0133] ICOFs were prepared by the tetraborate condensation reaction of diol and borohydride in an ampoule tube. A 5 mL ampoule tube was charged with 0.30 mmol diol (hydroquinone, 2,6- dihydroxynaphthalene, 4,4'-biphenol), and 0.15 mmol freshly opened borohydride (sodium borohydride or lithium borohydride) dispersed in 1 mL acetonitrile was added. After releasing all the H2 bubbles, the tube was frozen at 77K in liquid nitrogen bath for 2 min, then evacuated and refdled with N2 for three times and sealed at a pressure of 100 mtorr. The sealed tube was placed in an oven at 120°C for 3 days without disturbance. It was necessary to use the fresh-prepared borohydride suspension. A white powder precipitated, which was collected and purified by washing with acetonitrile and tetrahydrofuran to provide the ICOFs with a yield of 81%, 75%, and 85% for Na series and 72%, 80% and 92% for Li series, respectively.

[0134] Characterization

[0135] The Fourier-transform infrared spectroscopy (FT-IR) spectra were obtained from Agilent Technologies Cary 630 FT-IR. Solid-state cross polarization magic angle spinning (CP / MAS) nuclear magnate resonance (NMR) spectra were recorded on an Inova 400 NMR spectrometer. 7B MAS NMR was referred to Boron trifluoride etherate and 11 Li MAS NMR was referred to Lithium Chloride (IM solution in water). Deuterated solvents were purchased from Cambridge Isotope Laboratories (Andover, MA) and used as received. The powder angle X-ray diffraction pattern (PXRD) was conducted on Bruker D8 Advance A25 with Cu X-ray source (X = 1.5418 A) and measured by every 0.03 degree from 2 to 35 degree with an exposure time of 0.2 s. Scanning Electron Microscopy images (SEM) were recorded using a JSM-6480LV (LVSEM) at 10 kV. Thermogravimetric analysis was carried out using TA Instrument (Model: DSC SDT Q600) to determine the mass loss due to solvent and to study the thermal decomposition of ICOFs. For thermal stability / decomposition analysis, the sample was heated from 30°C to 800°C at a rate 5°C min-1 under nitrogen atmosphere. To study the stability of ICOF over numerous cycles, another thermogravimetric analyzer (TA Instrument, Simultaneous Thermal Analyzer, Model: SDT 650). About 10 mg of the pristine ICOF was loaded in an alumina pan and was heated to 120°C for 1 h in presence of flowing nitrogen (100 ml / min). After cooling down to 30°C, for cyclic testing, the nitrogen was switched to carbon dioxide. Each cycle consists of 30 min of gas adsorption at 30°C, followed by switching to nitrogen and simultaneously heating the sample to 100°C at 2°C min-1. The heating profile is shown in Fig. 49.

[0136] Gas Adsorption Measurement

[0137] The Quantachrome Autosorb ASiQ automated gas sorption analyzer was used to measure N2 adsorption isotherm at 77K for Brunauer-Emmett-Teller (BET) surface area analysis. The samples were heated at 80°C and kept at this temperature for 24 h under a vacuum for activation. Ultra-high purity grade (99.999 % purity) N2 were used for all free space corrections and measurements. For the gas adsorption measurement, the temperatures were controlled by using a refrigerated bath of liquid N2 (77 K).

[0138] Gas isotherms were measured in a home build batch adsorption system, used in Applicants previous works (34, 33) as given in schematic in Fig. 28a. In brief, Applicants measured the difference in pressure, hence volume of gas before and after it sees the adsorbent. Applicants load a certain mass of samples in the sample chamber and then vacuum on the sample for 8-10 h at temperature of 110°C. Between each isotherm measurement, the sample was outgassed at 110°C for 0.5 h and Applicants wait 0.5 h more for the temperature stabilization. Applicants calibrate the volume of the sample cell before the start of each measurement. After calibration, the gas of interest was introduced in the reference cell (volume = VR) and its pressure (PR) is recorded. Applicants open the valve connecting to the sample cell (new total volume = VS), and the new pressure (PS) is recorded.

[0139] In the presence of an adsorbent, some gas molecules will be adsorbed in their pores. These pressures and volumes are then correlated to obtain the total number of moles of gas adsorbed per unit mass of the adsorbent (n) using the following equation.

[0140] Where R is the universal gas constant, T is the temperature in Kelvin and w is the actual mass of the adsorbent. For each measurement, Applicants wait for the equilibrium to be achieved, where Applicants do not observe any uptake change higher than 0.2 cm3 g-1 for an hour. This value is an order of magnitude smaller compared to gas uptakes at highest pressure of 7 bar for the gases that are adsorbed by the material.

[0141] Isotherm Model Fitting and Thermodynamics

[0142] Isotherms collected at different temperatures were fitted to various available models in order to correlate the data. The simplest model to fit nonlinear isotherm is given by Langmuir model (75) which have been initially used to describe chemisorption on non-porous substrates and later to describe physical-adsorption of pure gases and mixture gases on porous materials (76, 77). The model assumes monolayer gas adsorption on to the adsorbate surface or pores. The following expression gives the Langmuir model:

[0143] Where qe,max (mmol g-1) is the saturation gas uptake related to monolayer capacity of the adsorbate, P (bar) is the pressure and KL is the Langmuir isotherm constant, which is related to the surface concentration dependent affinity. The isotherm constant is related to the temperature by the following equation: Where KLO is the isotherm constant at the initial temperature, Q is the isosteric heat of adsorption, R is the universal gas constant and T is the temperature. For an adsorbent which has a fixed shape and / or fixed number of adsorption sites, the KL values obtained at different temperatures should follow the equation u4.

[0144] Applicants studied the Langmuir Dual Site adsorption isotherm to understand if there exists more than one particular type of adsorption site in the adsorbent (48, 49). Dual site adsorption isotherm treats the adsorbent as a composition of two different adsorption site and fits in Langmuir isotherms on those two sites separately. The Langmuir Dual Site adsorption isotherm is given by:

[0145] Where, qemax,i and KLi, are the Langmuir Isotherm parameters for type ‘i’ site on the adsorbent, a is the fraction of one type of adsorption site, the For simplicity, Applicants assume an equal number of adsorption sites for both types of sites, thus converting equation u5 to the following expression.

[0146] If the values of the Langmuir constant for both the sites are close, then it would indicate the presence of only one type of adsorption site.

[0147] To probe more into the heterogeneity of the adsorbent site, Applicants used a more complex isotherm model. The Freundlich Isotherm model (50) gives estimate of both monolayer and multilayer adsorption on to heterogeneous surfaces. The isotherm is given by the following expression:

[0148] Where KF is the isotherm constant and nf provides an estimate of degree of heterogeneity. The value of nf =1 resembles Henry’s Law and indicates homogeneous surface. The Sips Isotherm model (57) combines both Langmuir and Freundlich model to generate a model which can describe adsorption on heterogeneous substrates while introducing a finite limit of the maximum adsorbed amount by introducing the term qmax. The following expression gives the Sips Isotherm model:

[0149] Where, KS and n are the Sips Isotherm constant and the heterogeneity factor. This introduces heterogeneity to the Langmuir isotherm model. A lower value of n indicates more heterogeneity of the adsorbent surface while n = 1 indicates that the adsorbent surface is homogeneous, and the Sips model reduces down to Langmuir model. Another model which is seldom used to study heterogeneous adsorbates is the Toth’s isotherm model (52) which assumes asymmetrical quasi-Gaussian distribution of energy at the adsorption sites. The following is the expression for Toth’s isotherm model:

[0150] Where KT is the Toth’s isotherm constant, and n gives a relative idea of heterogeneity of the adsorption sites. For n = 1, the model indicates the surface to be homogeneous and the Toth’s isotherm reduces down to Langmuir isotherm.

[0151] Mixture gas experiments and IAST selectivity calculations

[0152] For mixtures of inert gases such as N2, CFL, H2 etc., the mixture selectivity can be predicted accurately from single gas isotherms using the Ideal Adsorbed Solution Theory (IAST). The selectivity based on IAST was determined using IAST++ software package (53). Applicants also conducted mixture adsorption experiments for N2 and CH4 gas mixtures. Applicants slightly modified Applicants well calibrated, previously reported (.34, 35) home built volumetric gas adsorption system to accommodate for mixture gas adsorption (Fig. 28b). The composition of the gas mixtures before adsorption was controlled by mixing two streams of gases using mass flow controllers, and the gas phase composition during adsorption was measured using gas chromatography. The mixture adsorption data was collected until gas phase composition did not change in 5 h, indicating equilibrium.

[0153] ICOF Model Generation and Analysis

[0154] All crystal models were generated using the Material Studio 7.0 software package. The layered model referred to the single crystal structure of NaTB (37). To construct the dia topology with different interpenetration degree models, vertex positions were predetermined according to Reticular Chemistry Structure Resource (RCSR). After presetting the chemical structures and the unit cell, geometry optimization of the established models was performed by Materials Studio Forcite Module. To the further refinement, computed PXRD profiles were simulated from the structure models using the Materials Studio Reflex Module and were compared with experimental PXRD. Pawley refinement was then performed based on the proposed structure of ICOFs to iteratively optimize cell parameters until the Rwp residue converged and the refined profile showed good agreement with the experimentally observed profile.

[0155] Based on the modeled structure of ICOF-103-Li, ab initio molecular dynamics (AIMD) simulations were performed in a 1 X 1 X 2 supercell by the Vienna ab initio simulation package (VASP) version 5.4.4 in order to accurately model the interaction between Li+ and BO4- as well as between biphenyl groups (54-56). During the AIMD, the generalized gradient approximation (GGA) PBE potential for exchange correlation functional was used with the NPT ensemble and a cutoff energy of 520 eV (57). The structures of four different temperatures, 25°C, 55°C, 85°C, and 115°C were simulated for 60 picoseconds (ps) with the step size of 1 femtosecond. The atomic position, cell shape, and cell volume were all allowed to relax during simulations. For each run, the first 10 ps simulation was used for equilibration and the next 50 ps simulation was the production run. The angles between three neighboring boron atoms (B-B-B angle) in xy plane for each trajectory were then computed. The interaction energy landscape between a simulation snapshot structure and aN2 and H2 probe molecule was then generated by adding a probe molecule to the grid point and computing the interacting energy between the ICOF and the probe, where the grid is 16 16 11 with a grid spacing of 1 A. The pore volume in A3 is then defined as the number of grid points with a negative average interaction energy for the 50 ps production run trajectory, and the pore volume percentage is then computed by the ratio of the pore volume and the average cell volume.

[0156] REFERENCES

[0157] 1. E. A. Dolgopolova, A. M. Rice, C. R. Martin, N. B. Shustova, Photochemistry and photophysics of MOFs: steps towards MOF-based sensing enhancements. Chem. Soc. Rev. 47, 4710-4728 (2018).

[0158] 2. X. Liu, D. Huang, C. Lai, G. Zeng, L. Qin, H. Wang, H. Yi, B. Li, S. Liu, M. Zhang, Recent advances in covalent organicfram eworks (COFs) as a smart sensing material. Chem. Soc. Rev. 48, 5266-5302 (2019).

[0159] 3. S. Lin, C. S. Diercks, Y.-B. Zhang, N. Kornienko, E. M. Nichols, Y. Zhao, A. R. Paris, D. Kim, P. Yang, O. M. Yaghi, Covalent organic frameworks comprising cobalt porphyrins for catalytic CO2 reduction in water. Science. 349, 1208-1213 (2015). 4. Z. Jiang, X. Xu, Y. Ma, H. S. Cho, D. Ding, C Wang, J. Wu, P. Oleynikov, M Jia, J. Cheng, Filling metal-organic framework mesopores with TiO2 for CO2 photoreduction. Nature. 586, 549-554 (2020).

[0160] 5. M. Zhao, K. Yuan, Y. Wang, G. Li, J. Guo, L. Gu, W. Hu, H. Zhao, Z. Tang, Metalorganic frameworks as selectivity regulators for hydrogenation reactions. Nature. 539, 76-80 (2016).

[0161] 6. R. V Jagadeesh, K. Murugesan, A. S. Alshammari, H. Neumann, M.-M. Pohl, J. Radnik, M. Beller, MOF-derived cobalt nanoparticles catalyze a general synthesis of amines. Science. 358, 326-332 (2017).

[0162] 7. Z. R. Herm, B. M. Wiers, J. A. Mason, J. M. van Baten, M. R. Hudson, P. Zajdel, C. M. Brown, N. Masciocchi, R. Krishna, J. R. Long, Separation of hexane isomers in a metal-organic framework with triangular channels. Science. 340, 960-964 (2013).

[0163] 8. Y. Belmabkhout, P. M. Bhatt, K. Adil, R. S. Pillai, A. Cadiau, A. Shkurenko, G. Maurin, G. Liu, W. J. Koros, M. Eddaoudi, Natural gas upgrading using a fluorinated MOF with tuned H2S and CO2 adsorption selectivity. Nat. Energy. 3, 1059-1066 (2018).

[0164] 9. Q.-F. Lin, Z. R. Gao, C. Lin, S. Zhang, J. Chen, Z. Li, X. Liu, W. Fan, J. Li, X. Chen, A stable aluminosilicate zeolite with intersecting three-dimensional extra-large pores. Science. 374, 1605-1608 (2021).

[0165] 10. H. Furukawa, K. E. Cordova, M. O’Keeffe, O. M. Yaghi, The chemistry and applications of metal-organic frameworks. Science. 341, 1230444 (2013).

[0166] 11. O. M. Yaghi, M. J. Kalmutzki, C. S. Diercks, Introduction to reticular chemistry: metal-organic frameworks and covalent organic frameworks (John Wiley & Sons, 2019).

[0167] 12. C. Xu, W. Wei, Y. He, Enhanced hydrogen separation performance of Linde Type-A zeolite molecular sieving membrane by cesium ion exchange. Mater. Lett. 324, 132680 (2022).

[0168] 13. S. Aguado, G. Bergeret, C. Daniel, D. Farrusseng, Absolute molecular sieve separation of ethylene / ethane mixtures with silver zeolite A. J. Am. Chem. Soc. 134, 14635-14637 (2012).

[0169] 14. S. Kitagawa, K. Uemura, Dynamic porous properties of coordination polymers inspired by hydrogen bonds. Chem. Soc. Rev. 34, 109-119 (2005).

[0170] 15. J. Dong, V. Wee, D. Zhao, Stimuli-responsive metal-organic frameworks enabled by intrinsic molecular motion. NatMater. 21, 1334-1340 (2022).

[0171] 16. C. Serre, C. Mellot-Draznieks, S. Surble, N. Audebrand, Y. Filinchuk, G. Ferey, Role of solvent-host interactions that lead to very large swelling of hybrid frameworks. Science. 315, 1828-1831 (2007).

[0172] 17. H. Xiong, Z. Liu, X. Chen, H. Wang, W. Qian, C. Zhang, A. Zheng, F. Wei, In situ imaging of the sorption-induced sub-cell topological flexibility of a rigid zeolite framework. Science. 376, 491-496 (2022).

[0173] 18. L. Zhang, S. Jee, J. Park, M. Jung, D. Wallacher, A. Franz, W. Lee, M. Yoon, K. Choi, M. Hirscher, Exploiting dynamic opening of apertures in a partially fluorinated MOF for enhancing H2 desorption temperature and isotope separation. J.Am. Chem. Soc. 141, 19850-19858 (2019). 19. S. M. Kuznicki, V. A. Bell, S. Nair, H. W. Hillhouse, R. M. Jacubinas, C. M. Braunbarth, B. H. Toby, M. Tsapatsis, A titanosilicate molecular sieve with adjustable pores for size-selective adsorption of molecules. Nature. 412, 720-724(2001).

[0174] 20. M.-A. Springuel-Huet, A. Nossov, Z. Adem, F. Guenneau, C. Volkringer, T. Loiseau, G. Ferey, A. Gedeon, 129Xe NMR study of the framework flexibility of the porous hybrid MIL- 53 (Al). J. Am. Chem. Soc. 132, 11599-11607 (2010).

[0175] 21. C. Serre, F. Millange, C. Thouvenot, M. Nogues, G. Marsolier, D. Louer, G. Ferey, Very large breathing effect in the first nano porous chromium (III)-Based solids: MIL-53 or CrIII (OH)O{O2C- C6H4- CO2}O{HO2C- C6H4- CO2H} x0 H2Oy.J. Am. Chem. Soc. 124, 13519-13526 (2002).

[0176] 22. K. Barthelet, J. Marrot, D. Riou, G. Ferey, A breathing hybrid organic-inorganic solid with very large pores and high magnetic characteristics. Angew. Chemie Int. Ed. 41, 281-284 (2002).

[0177] 23. H. Oh, S. B. Kalidindi, Y. Um, S. Bureekaew, R. Schmid, R. A. Fischer, M. Hirscher, A cryogenically flexible covalent organic framework for efficient hydrogen isotope separation by quantum sieving. Angew. Chemie Int. Ed. 52, 13219-13222 (2013).

[0178] 24. Y. Su, K. Otake, J. -J. Zheng, S. Horike, S. Kitagawa, C. Gu, Separating water isotopologues using diffusion-regulatory porous materials. Nature. 611, 289-294 (2022).

[0179] 25. C. Gu, N. Hosono, J. -J. Zheng, Y. Sato, S. Kusaka, S. Sakaki, S. Kitagawa, Design and control of gas diffusion process in an anoporous soft crystal. Science. 363, 387-391 (2019).

[0180] 26. K. Geng, T. He, R. Liu, S. Dalapati, K. T. Tan, Z. Li, S. Tao, Y. Gong, Q. Jiang, D. Jiang, Covalent Organic Frameworks: Design, Synthesis, and Functions. Chem. Rev. 120, 8814— 8933 (2020).

[0181] 27. S.-Y. Ding, W. Wang, Covalent organic frameworks (COFs): from design to applications. Chem. Soc. Rev. 42, 548-568 (2013).

[0182] 28. C. S. Diercks, O. M. Yaghi, The atom, the molecule, and the covalent organic framework. Science. 355, eaall585 (2017).

[0183] 29. A. M. Evans, L. R. Parent, N. C. Flanders, R. P. Bisbey, E. Vitaku, M. S. Kirschner, R. D. Schaller, L. X. Chen, N. C. Gianneschi, W. R. Dichtel, Seeded growth of single-crystal two- dimensional covalent organic frameworks. Science. 361, 52-57 (2018).

[0184] 30. Y. Hu, S. J. Teat, W. Gong, Z. Zhou, Y. Jin, H. Chen, J. Wu, Y. Cui, T. Jiang, X. Cheng, Single crystals of mechanically entwined helical covalent polymers. Nat. Chem. 13, 660- 665 (2021).

[0185] 31. I. M. Malkowsky, R. Frohlich, U. Griesbach, H. Putter, S. R. Waldvogel, Facile and reliable synthesis of tetraphenoxy borates and their properties. Eur. J. Inorg. Chem. 8, 1690-1697 (2006).

[0186] 32. H. M. El-Kaderi, J. R. Hunt, J. L. Mendoza-Cortes, A. P. Cote, R. E. Taylor, M. O’Keeffe, O. M. Yaghi, Designed synthesis of 3D covalent organic frameworks. Science. 316, 268-272 (2007). 33. T. Ma, E. A. Kapustin, S. X. Yin, L. Liang, Z. Zhou, J. Niu, L.-H. Li, Y. Wang, J. Su, J. Li, Single-crystal x-ray diffraction structures of covalent organic frameworks. Science. 361, 48- 52 (2018).

[0187] 34. Q. Dong, Z. Song, F. Zhou, H. Li, M. Yu, Ultrathin, fine-tuned microporous coating modified 5A zeolite for propan e / propylene adsorptive separation. Microporous Mesoporous Mater. 281, 9-14 (2019).

[0188] 35. Z. Song, Q. Dong, W. L. Xu, F. Zhou, X. Liang, M. Yu, Molecular layer deposition- modified 5A zeolite for highly efficient CO2 capture. ACS Appl. Mater. Interfaces. 10, 769-775 (2018).

[0189] 36. F. A. A. Kareem, A. M. Shariff, S. Ullah, N. Mellon, L. K. Keong, Adsorption of pure and predicted binary (CO2: CH4) mixtures on 13X-Zeolite: Equilibrium and kinetic properties at offshore conditions. Microporous Mesoporous Mater. 267,221-234 (2018).

[0190] 37. S. Nandi, P. De Luna, T. D. Daff, J. Rother, M. Liu, W. Buchanan, A. I. Hawari, T. K. Woo, R. Vaidhyanathan, A single-ligand ultra-microporous MOF for precombustion CO2 capture and hydrogen purification. Sci. Adv. 1, el500421 (2015).

[0191] 38. M. T. Kapelewski, T. Runcevski, J. D. Tarver, H. Z. H. Jiang, K. E. Hurst, P. A. Parilla, A. Ayala, T. Gennett, S. A. FitzGerald, C. M. Brown, Record high hydrogen storage capacity in the metal-organic framework Ni2 (m-dobdc) at near-ambient temperatures. Chem. Mater. 30, 8179-8189 (2018).

[0192] 39. J. A. Mason, M. Veenstra, J. R. Long, Evaluating metal-organic frameworks for natural gas storage. Chem. Sci. 5, 32-51 (2014).

[0193] 40. W. Zhang, J. Maul, D. Vulpe, P. Z. Moghadam, D. Fairen- Jimenez, D. M. Mittleman, J. A. Zeitler, A. Erba, M. T.Ruggiero, Probing the mechanochemistry of metal-organic frameworks with low-frequency vibrational spectroscopy. J.Phys. Chem. C. 122, 27442-27450 (2018).

[0194] 41. M. R. Ryder, B. Civalleri, T. D. Bennett, S. Henke, S. Rudic, G. Cinque, F. Fernandez- Alonso, J.-C. Tan, Identifying the role of terahertz vibrations in metal-organic frameworks: from gate-opening phenomenon to shear-driven structural destabilization. Phys. Rev. Lett. 113, 215502 (2014).

[0195] 42. X. Wang, M. Bahri, Z. Fu, M. A. Little, L. Liu, H. Niu, N. D. Browning, S. Y. Chong,

[0196] L. Chen, J. W. Ward, A cubic 3Dcovalent organic framework with nbo topology. J. Am. Chem. Soc. 143, 15011-15016 (2021).

[0197] 43. H. Deng, M. A. Olson, J. F. Stoddart, O. M. Yaghi, Robust dynamics. Nat. Chem. 2, 439-443 (2010).

[0198] 44. S. Li, Z. Zong, S. J. Zhou, Y. Huang, Z. Song, X. Feng, R. Zhou, H. S. Meyer, M. Yu,

[0199] M. A. Carreon, SAPO-34 Membranes for N2 / CH4 separation: Preparation, characterization, separation performance and economic evaluation. J.Memb. Sci. 487, 141-151 (2015).

[0200] 45. 1. Langmuir, The adsorption of gases on plane surfaces of glass, mica and platinum. J. Am. Chem. Soc. 40, 1361-1403(1918).

[0201] 46. U. Hamid, P. Vyawahare, H. Tun, C. Chen, Generalization of thermodynamic Langmuir isotherm for mixed-gas adsorption equilibria. AIChEJ. 68, el7663 (2022). 47. M. Mabuza, K. Premlall, M. O Daramola, Modelling and thermodynamic properties of pure CO2 and flue gas sorption data on South African coals using Langmuir, Freundlich, Temkin, and extended Langmuir isotherm models. Int. J. Coal Sci. Technol. 9, 1-15 (2022).

[0202] 48. P. M. Mathias, R. Kumar, J. D. Moyer, J. M. Schork, S. R. Srinivasan, S. R. Auvil, O. Talu, Correlation of multicomponent gas adsorption by the dual-site Langmuir model. Application to nitrogen / oxygen adsorption on 5A-zeolite. Ind. Eng. Chem. Res. 35, 2477-2483 (1996).

[0203] 49. M. Z. A. Zulkifli, A. Mukhtar, M. F. M. Fadli, A. M. S. Bahari, A. Matsumoto, H. Misran, CFD Simulation of CO2 and Methane Adsorption at Various Temperature for MOF-5 using Dual -site and Single-site Langmuir Model. CFD Lett. 13,1-10 (2021).

[0204] 50. H. Freundlich, Uber die Adsorption in Lbsungen. Habilitationsschrift durch welche... zu haltenden Probevorlesung" Kapillarchemie und Physiologic" einladet Dr. Herbert Freundlich (W. Engelmann, 1906).

[0205] 51. R. Sips, On the structure of a catalyst surface. J. Chem. Phys. 16, 490-495 (1948).

[0206] 52. J. Toth, Calculation of the BET-compatible surface area from any type I isotherms measured above the critical temperature. JColloid Interface Set. 225, 378-383 (2000).

[0207] 53. S. Lee, J. H. Lee, J. Kim, User-friendly graphical user interface software for ideal adsorbed solution theory calculations. Korean J. Chem. Eng. 35, 214-221 (2018).

[0208] 54. G. Kresse, J. Furthmuller, Efficient iterative schemes for ab initio total-energy calculations using a plane-wave basis set. Phys. Rev. B. 54, 11169 (1996).

[0209] 55. G. Kresse, J. Furthmuller, Efficiency of ab-initio total energy calculations for metals and semiconductors using a plane-wave basis set. Compnt. Mater. Sci. 6, 15-50 (1996).

[0210] 56. G. Kresse, J. Furthmuller, J. Hafner, Theory of the crystal structures of selenium and tellurium: the effect of generalized-gradient corrections to the local-density approximation. Phys. Rev. B. 50, 13181 (1994).

[0211] 57. G. Kresse, D. Joubert, From ultrasoft pseudopotentials to the projector augmented- wave method. Phys. Rev. b. 59, 1758(1999).

[0212] 58. L. Hauchhum, P. Mahanta, Carbon dioxide adsorption on zeolites and activated carbon by pressure swing adsorption in affixed bed. Int. J. Energy Environ. Eng. 5, 349-356 (2014).

[0213] 59. G. Mondino, C. A. Grande, R. Blom, L. O. Nord, Moving bed temperature swing adsorption for CO2 capture from a natural gas combined cycle power plant. Int. J. Greenh. Gas Control. 85, 58-70 (2019).

[0214] 60. N. S. Wilkins, A. Rajendran, Measurement of competitive CO2 and N2 adsorption on Zeolite 13X for post-combustion CO2 capture. Adsorption. 25, 115-133 (2019).

[0215] 61. P. Wu, Y. Li, J. -J. Zheng, N. Hosono, K. Otake, J. Wang, Y. Liu, L. Xia, M. Jiang, S. Sakaki, Carbon dioxide capture and efficient fixation in a dynamic porous coordination polymer. Nat. Commun. 10, 1-8 (2019).

[0216] 62. J. Nishida, A. Tamimi, H. Fei, S. Pullen, S. Ott, S. M. Cohen, M. D. Fayer, Structural dynamics inside a functionalized metal-organic framework probed by ultrafast 2D IR spectroscopy. Proc. Natl. Acad. Sci. I l l, 18442-18447 (2014). 63. A. D. Buckingham, R.-L. Disch, D. A. Dunmur, Quadrupole moments of some simple molecules. J. Am. Chem. Soc. 90, 3104-3107 (1968).

[0217] 64. T. K. Bose, J. S. Sochanski, R. H. Cole, Dielectric and pressure virial coefficients of imperfect gases. V. Octopole moments of CH4 and CF4. J. Chem. Phys. 57, 3592-3595 (1972).

[0218] 65. M. Guisnet, J.-P. Gilson, Zeolites for cleaner technologies (Imperial College Press London, London, 2002), vol. 3.

[0219] 66. E. M. Flanigen, R. W. Broach, S. T. Wilson, Zeolites in industrial separation and catalysis. Chapter. 1, 1-26 (2010).

[0220] 67. J.-R. Li, R. J. Kuppler, H.-C. Zhou, Selective gas adsorption and separation in metalorganic frameworks. Chem. Soc. Rev. 38, 1477-1504 (2009).

[0221] 68. S. Sircar, Basic research needs for design of adsorptive gas separation processes. Ind. Eng. Chem. Res. 45, 5435-5448(2006).

[0222] 69. J. Liu, H. Shang, J. Yang, J. Wang, J. Li, S. Deng, Novel zeolite / carbon monolith adsorbents for efficient CH4 / N2 separation. Chem. Eng. J. 426, 130163 (2021).

[0223] 70. R. S. Pillai, J. W. Yoon, S.-J. Lee, Y. K. Hwang, Y.-S. Bae, J.-S. Chang, G. Maurin, N2 capture performances of the hybrid porous MIL-101 (Cr): from prediction toward experimental testing. J. Phys. Chem. C. 121, 22130-22138 (2017).

[0224] 71. F. Zhang, H. Shang, L. Wang, Y. Wang, J. Yang, Y. Xia, H. Li, L. Li, J. Li, Construction of a Porous Metal-Organic Framework with a High Density of Open Cr Sites for Record N2 / O2 Separation. Adv. Mater. 33, 2100866 (2021).

[0225] 72. F. Zhang, K. Li, J. Chen, X. Zhang, K. Li, H. Shang, L. Ma, W. Guo, X. Wu, J. Yang, Efficient N2 / CH4 separation in a stable metal-organic framework with high density of open Cr sites. Sep. Purif. Technol. 281, 119951 (2022).

[0226] 73. D. A. Kennedy, M. Mujcin, E. Trudeau, F. H. Tezel, Pure and binary adsorption equilibria of methane and nitrogen on activated carbons, desiccants, and zeolites at different pressures. J. Chem. Eng. Data. 61, 3163-3176 (2016).

[0227] 74. P. S. Barcia, L. Bastin, E. J. Hurtado, J. A. C. Silva, A. E. Rodrigues, B. Chen, Single and multicomponent sorption of CO2, CH4 and N2 in a microporous metal-organic framework. Sep. Sci. Technol. 43, 3494-3521 (2008).

[0228] 75. E. Kouvelos, K. Kesore, T. Steriotis, H. Grigoropoulou, D. Bouloubasi, N. Theophilou, S. Tzintzos, N. Kanelopoulos, High pressure N2 / CH4 adsorption measurements in clinoptilolites. Microporous Mesoporous Mater. 99, 106-111 (2007).

[0229] 76. Y. Park, D.-K. Moon, Y.-H. Kim, H. Ahn, C.-H. Lee, Adsorption isotherms of CO2, CO, N2, CH4, Ar and H2 on activated carbon and zeolite LiX up to 1 .0 MPa. Adsorption. 20, 631— 647 (2014).

[0230] 77. S. Cavenati, C. A. Grande, A. E. Rodrigues, Layered pressure swing adsorption for methane recovery from CH4 / CO2 / N2 streams. Adsorption. 11, 549-554 (2005).

[0231] 78. X. Wu, B. Yuan, Z. Bao, S. Deng, Adsorption of carbon dioxide, methane and nitrogen on an ultra-microporous coppe rmetal-organic framework. J. Colloid Interface Sci. 430, 78-84 (2014). 79. Y. Zhang, W. Su, Y. Sun, J. Liu, X. Liu, X. Wang, Adsorption Equilibrium of N2, CH4, and C02 on MIL-101. J. Chem.Eng. Data. 60, 2951-2957 (2015).

[0232] 80. Y. Li, R. T. Yang, Gas adsorption and storage in metal- organic framework MOF-177. Langmuir. 23, 12937-12944(2007).

[0233] 81. M. Andrade, S. C. Rodrigues, A. Mendes, High performing CMS adsorbent for O2 / N2 separation. Microporous Mesoporous Mater. 296, 109989 (2020).

[0234] 82. D. Park, Y. Ju, J.-H. Kim, H. Ahn, C.-H. Lee, Equilibrium and kinetics of nitrous oxide, oxygen and nitrogen adsorption on activated carbon and carbon molecular sieve. Sep. Purif Technol. 223, 63-80 (2019).

[0235] 83. Y.-J. Park, S.-J. Lee, J.-H. Moon, D.-K. Choi, C.-H. Lee, Adsorption equilibria of 02, N2, and Ar on carbon molecular sieve and zeolites 10X, 13X, and LiX. J. Chem. Eng. Data. 51, 1001-1008 (2006).

[0236] 84. J. A. Dunne, M. Rao, S. Sircar, R. J. Gorte, A. L. Myers, Calorimetric heats of adsorption and adsorption isotherms. 2. 02, N2, Ar, CO2, CH4, C2H6, and SF6 on NaX, H-ZSM- 5, and Na-ZSM-5 zeolites. Langmuir. 12, 5896-5904 (1996).

[0237] 85. J. C. Santos, P. Cruz, T. Regala, F. D. Magalhaes, A. Mendes, High-purity oxygen production by pressure swing adsorption. Ind. Eng. Chem. Res. 46, 591-599 (2007).

[0238] 86. Y. Tang, X. Wang, Y. Wen, X. Zhou, Z. Li, Oxygen-selective adsorption property of ultra microporous MOF Cu(Qc)2 for air separation. Ind. Eng. Chem. Res. 59, 6219-6225 (2020).

[0239] 87. O. Leal, D. L. Anderson, R. G. Bowman, F. Basolo, R. L. Burwell Jr, Reversible adsorption of oxygen on silica gel modified by imidazole-attached iron tetraphenylporphyrin. J. Am. Chem. Soc. 97, 5125-5129 (1975).

[0240] 88. A. Jaffe, M. E. Ziebel, D. M. Halat, N. Biggins, R. A. Murphy, K. Chakarawet, J. A. Reimer, J. R. Long, Selective, High-Temperature 02 Adsorption in Chemically Reduced, Redox- Active Iron-Pyrazolate Metal-Organic Frameworks. J. Am.Chem. Soc. 142, 14627-14637 (2020).

[0241] 89. E. D. Bloch, L. J. Murray, W. L. Queen, S. Chavan, S. N. Maximoff, J. P. Bigi, R. Krishna, V. K. Peterson, F. Grandjean, G. J. Long, Selective binding of 02 over N2 in a redoxactive metal-organic framework with open iron (II) coordination sites. J. Am. Chem. Soc. 133, 14814-14822 (2011).

[0242] 90. W. Zhang, D. Banerjee, J. Liu, H. T. Schaef, J. V Crum, C. A. Fernandez, R. K. Kukkadapu, Z. Nie, S. K. Nune, R. K. Motkuri, Redox-Active Metal-Organic Composites for Highly Selective Oxygen Separation Applications. Adv. Mater. iL 3572-3577 (2016).

[0243] 91. A. Jayaraman, R. T. Yang, S.-H. Cho, T. S. G. Bhat, V. N. Choudary, Adsorption of nitrogen, oxygen and argon on Na-CeX zeolites. Adsorption. 8, 271-278 (2002).

Claims

CLAIMSWhat is claimed is1. A microporous crystalline lattice composition comprising a plurality of chemical subunits bound by a series of cross-linked covalent tetraphenoxyb orate linkages and weak ion-dipole interactions forming an ionic covalent organic framework (ICOF) having a plurality of tunable iso-surface channels.

2. The composition of claim 1, wherein said chemical subunits are selected from:or a combination of the same, and wherein, X+is a metal ion.

3. The composition of any of claims 1-2, wherein said metal ion is selected from Li+or Nat4. The composition of any of claims 1-3, wherein said chemical subunits are crosslinked in an xy plane by a strong covalent tetraphenborate bond between the O and B of the chemical subunits, and in a y plane through the weak ion-dipole interaction between the O of the chemical subunits and the metal ion.

5. The composition of any of claims 1-4, wherein said tunable iso-surface channels are continuously tunable via changes in temperature.

6. The composition of any of claims 1-5, wherein said tunable iso-surface channels are reversibly tunable.

7. The composition of any of claims 1-6, wherein said tunable iso-surface channels are continuously tunable between approximately 2.9 to 4.0 A, with resolution at or below 0.2 A.

8. The composition of any of claims 1-7, wherein said tunable iso-surface channels selectively adsorb a gas compound via thermo-regulatory molecular sieving (TRMS).

9. The composition of any of claims 1-8, wherein in said selectively adsorbed gas is selected from: H2, CO2, O2, N2 and CH4.

10. A microporous crystalline lattice composition comprising a series of crosslinked chemical subunits forming an ionic covalent organic framework (ICOF) having a plurality of tunable isosurface channels, wherein said chemical subunits are selected from:or a combination of the same, wherein, X+is a metal ion selected from Li+or Nat11. The composition of claim 10, wherein said chemical subunits are crosslinked in an xy plane by a strong covalent tetraphenborate bond between the O and B of the chemical subunits, and in a y plane through the weak ion-dipole interaction between the O of the chemical subunits and the metal ion.

12. The composition of any of claims 10-11, wherein said tunable iso-surface channels are continuously tunable via changes in temperature.

13. The composition of any of claims 10-12, wherein said tunable iso-surface channels are reversibly tunable.

14. The composition of any of claims 10-13, wherein said tunable iso-surface channels are continuously tunable between approximately 2.9 to 4.0 A, with resolution at or below 0.2 A.

15. The composition of any of claims 10-14, wherein said tunable iso-surface channels selectively adsorb a gas compound via thermo-regulatory molecular sieving (TRMS).

16. The composition of any of claims 10-15, wherein in said selectively adsorbed gas is selected from: H2, CO2, O2, N2 and CH4.

17. A method of synthesizing a microporous crystalline lattice composition comprising contacting a diol linker with a borohydride salt under conditions sufficient to produce a condensation reaction forming a chemical subunit, wherein the chemical subunit is configured to be crosslinked forming an ionic covalent organic framework (ICOF) having a plurality of tunable iso-surface channels.

18. The method of claim 17, wherein said borohydride salt is selected from sodium borohydride or lithium borohydride.

19. The method of any of claims 17-18, wherein said diol comprises an aromatic diol.

20. The method of any of claims 17-19, wherein said aromatic diol is selected from hydroquinone, 2,6-dihydroxynaphthalene, or 4,4'-biphenol, or a combination of the same.

21. The method of any of claims 17-20, wherein said chemical subunit comprises a series of chemical subunits are crosslinked by a series of cross-linked covalent tetraphenoxyborate linkages and weak ion-dipole interactions forming the ICOF having a plurality of tunable iso-surface channels.

22. The method of any of claims 17-21, wherein chemical subunit is selected from:or a combination of the same, wherein, X+is a metal ion selected from Li+or Nat23. The method of any of claims 17-22, wherein said chemical subunits are crosslinked in an xy plane by a strong covalent tetraphenborate bond between the O and B of the chemical subunits, and in a y plane through the weak ion-dipole interaction between the O of the chemical subunits and the metal ion.

24. The method of any of claims 17-23, wherein said tunable iso-surface channels are continuously tunable via changes in temperature.

25. The method of any of claims 17-24, wherein said tunable iso-surface channels are reversibly tunable.

26. The method of any of claims 18-25, wherein said tunable iso-surface channels are continuously tunable between approximately 2.9 to 4.0 A, with resolution at or below 0.2 A.

27. The method of any of claims 17-26, wherein said tunable iso-surface channels selectively adsorb a gas compound via thermo-regulatory molecular sieving (TRMS).

28. The method of any of claims 17-27, wherein in said selectively adsorbed gas is selected from: H2, CO2, O2, N2 and CH4.

29. A method for separating a complex gas mixture comprising:- contacting a complex gas mixture containing at least two different gases with a microporous crystalline lattice composition comprising a series of chemical subunits bound by a series of cross-linked covalent tetraphenoxyborate linkages and weak ion-dipole interactions forming an ionic covalent organic framework (ICOF) having a plurality of tunable iso-surface channels;- wherein the temperature of the ICOF is adjusted to selectively adsorb at least one gas of the complex mixture.

30. The composition of claim 29, wherein said chemical subunits are selected from:or a combination of the same, wherein, X+is a metal ion.

31. The composition of any of claims 29-30, wherein said metal ion is selected from Li+or Na+.

32. The composition of any of claims 29-31, wherein said chemical subunits are crosslinked in an xy plane by a strong covalent tetraphenborate bond between the O and B of the chemical subunits, and in a plane through the weak ion-dipole interaction between the O of the chemical subunits and the metal ion.

33. The composition of any of claims 29-32, wherein said tunable iso-surface channels are continuously tunable via changes in temperature.

34. The composition of any of claims 29-33, wherein said tunable iso-surface channels are reversibly tunable.

35. The composition of any of claims 29-34, wherein said tunable iso-surface channels are continuously tunable between approximately 2.9 to 4.0 A, with resolution at or below 0.2 A.

36. The composition of any of claims 29-35, wherein said tunable iso-surface channels selectively adsorb a gas compound via thermo-regulatory molecular sieving (TRMS).

37. The composition of any of claims 29-36, wherein in said complex gas mixture comprises at least two of the following: H2, CO2, O2, N2 and CH4.

38. The composition of any of claims 29-37, wherein in said selectively adsorbed gas is selected from: H2, CO2, O2, N2 and CH4.

39. A microporous crystalline lattice composition comprising a series of crosslinked chemical subunits having a chemical formula according to Formula I:wherein, X+is a metal ion selected from Li+or Na+.

40. A microporous crystalline lattice composition comprising a series of crosslinked chemical subunits having a chemical formula according to Formula II:wherein, X+is a metal ion selected from Li+or Nat41. A microporous crystalline lattice composition comprising a series of crosslinked chemical subunits having a chemical formula according to Formula III:wherein, X+is a metal ion selected from Li+or Nat42. A method for separating or differentiating different gases in a mixture of gases comprising contacting the mixture of gas with an ionic covalent organic framework (ICOF) of the present disclosure.

43. A method for storing gas comprising contacting a gas with an ionic covalent organic framework (ICOF) of the present disclosure.

44. A method according to any one of claims 42 to 43, wherein the gas is or the gas mixture comprises H2, CO2, N2, O2, and / or CH4.

Images