New elongation-functionalization strategy for water-harvesting MOFs

Abstract

Novel water-stable metal-organic framework (MOF) compositions with linker elongation / functionalization result in higher water uptake at low relative humidity.

Description

Technical Field

[0001] This invention was made with government support under Award Number HR0011-21-C-002 from the Department of Defense Advanced Research Projects Agency. The United States Government has certain rights in this invention.

Background Art

[0002] Approximately one-third of the world's population lives in arid regions with limited access to clean water. 1 Therefore, innovative solutions to address this global water crisis, which affects millions of people, are urgently needed. Atmospheric water makes up 10 18 cubic meters and constitutes 3% of all fresh water available on Earth. 2 This water, which is present everywhere at all times, can help alleviate the global water crisis if harvested. 3

[0003] Metal-organic frameworks (MOFs) have emerged as promising materials for atmospheric water capture. 4,5 Several MOFs have been shown to exhibit three major characteristics for this purpose: 1) high water stability, 2) a sharp water uptake step at low relative humidity (RH) (less than 40%), and 3) low regeneration energy for recycling. Importantly, unlike other porous materials 6 , MOFs demonstrate a high potential for tunability of surface area, pore volume, and pore structure through molecular-level modification. MOFs demonstrate a high potential for tunability of surface area, pore volume, and pore structure through molecular-level modification that directly affects their water sorption properties. Enhancing water absorbency at low RH while retaining all of the above characteristics has been a long-standing challenge in the study of water-harvesting MOFs.

[0004] In addition to MOFs, the water sorption properties of various materials such as silica gel, porous polymers, and zeolites have been tested. 10However, all of them have drawbacks that prevent their use in water harvesting devices. Zeolites exhibit rapid water absorption at low pH but require an enormous amount of energy for regeneration. In other situations, zeolites experience structure poisoning that adversely affects their effectiveness due to permanent water entrapment in their pores. The water sorption isotherm profiles of silica gel and porous polymers lack steepness, reducing the working capacity of these materials. Summary of the Invention Problems to be Solved by the Invention

[0005] Only a few examples of MOFs have been shown to demonstrate the desirable properties for water harvesting applications. 11 The hydrophilicity and hydrophobicity of most MOF structures are ongoing issues 12 and thus there is a great need for new structures. Means for Solving the Problems

[0006] Herein, a new water-stable MOF with high water absorption at low RH compared to previous analogs is reported. 7,8,9 In the present disclosure, a linker elongation / functionalization strategy for obtaining MOF structures with enhanced water absorption capacity is introduced. By elongation of the linker where at least one of m or n is 1 - 5, MOFs with enhanced pore size and volume are provided. Further, modification of their heterocyclic cores (X, Y, Z, I) of the elongated linker or introduction of substituents (R 1 ~R 5 ) can be used to adjust or tune the water sorption properties of each MOF.

[0007] The disclosed linker elongation / functionalization strategy can be used to enhance the water absorption of existing MOFs without significant negative effects on their long lifespan and hydrophilicity.

[0008] The targeted objective of the described linker elongation / functionalization strategy is to enhance the water absorption of the MOF for placement within a water harvesting device. This application can reduce the use of materials for capturing the same amount of moisture compared to previously utilized MOFs at a desired RH.

[0009] Furthermore, additional modifications of the elongated linker result in various MOF structures with diverse water harvesting properties. Thus, in addition to water harvesting devices, dehumidifiers, heat pumps, adsorption refrigerators, and other appliances can benefit from the use of these novel MOF structures.

[0010] In one aspect, the present invention provides a novel water-stable metal-organic framework (MOF) composition with linker elongation / functionalization that provides higher water absorption at low relative humidity.

[0011] In one aspect, the present invention is a metal-organic framework (MOF) composition having the following formula:

[0012]

Chemical formula

[0013] [wherein, X, Y, Z are independently C(H), N(H), O, or S, R 1 ~R 5 are independently CH 3 , NH 2 , OH, halogen, or H, m is an integer from 0 to 5, n is an integer from 1 to 5, l is an integer of 1 or 2, b1 and b2 are independently a single bond or a double bond, at least one b2 is a double bond] and provides an MOF composition comprising a metal complexed with a linker of

[0014] In one aspect, the present invention provides a metal-organic framework (MOF) comprising a repeating core, wherein the core comprises secondary building units linked to an organic ligand (linker), the secondary building units comprise one or more metals or metal-containing complexes, the organic ligand (linker) has the formula I (above), and the secondary building units are linked to the organic ligand via oxygen atoms of carboxylate groups in the organic ligand (linker).

[0015] In embodiments, R 1 ~R 5 is H, or R 1 ~R 5 one, two, three, four or five of are CH 3 , NH 2 , OH or halogen.

[0016] m is 0, 1 or 2, and n is 1, 2 or 3, m is 0, 1 or 2, and n is 1 or 2, m is 0 and n is 1, m is 0 and n is 2, m is 1 and n is 1, m is 1 and n is 2, m is 1 and n is 3, m is 2 and n is 2, m is 2 and n is 3, or m is 3 and n is 3.

[0017] l is 1.

[0018] One, two or three of X, Y, Z are independently N(H), O or S, or X and Y are N and NH respectively, and Z is C.

[0019] In embodiments, the MOF composition has the formula II:

[0020] [Chemical formula]

[0021] [wherein, R 1 is H, NH 2 or OH, R 2 is H, NH 2 or OH, R 3 is H, NH 2 or OH] contains the linker of.

[0022] In one aspect, the present invention provides a MOF or composition herein, wherein the linker contains the formula of Table 1, 2, 3 or 4 (Table 1, 2, 3 or 4).

[0023] In an embodiment, the metal is Li + , Na + , K + , Rb + , Cs + , Be 2+ , Mg 2+ , Ca 2+ , Sr 2+ , Ba 2+ , Sc 3+ , Sc 2+ , Sc + , Y 3+ , Y 2+ , Y + , Ti 4+ , Ti 3+ , Ti 2+ , Zr 4+ , Zr 3+ , Zr 2+ , Hf 4+ , Hf 3+ , V 5+ , V 4+ , V 3+ , V 2+ , Nb 5+ , Nb 4+ , Nb 3+ , Nb 2+ , Ta 5+ , Ta 4+ , Ta 3+ , Ta2+ 、Cr 6+ 、Cr 5+ 、Cr 4+ 、Cr 3+ 、Cr 2+ 、Cr + 、Cr, Mo 6+ 、Mo 5+ 、Mo 4+ 、Mo 3+ 、Mo 2+ 、Mo + 、Mo, W 6+ 、W 5+ 、W 4+ 、W 3+ 、W 2+ 、W + 、W, Mn 7+ 、Mn 6+ 、Mn 5+ 、Mn 4+ 、Mn 3+ 、Mn 2+ 、Mn + 、Re 7+ 、Re 6+ 、Re 5+ 、Re 4+ 、Re 3+ 、Re 2+ 、Re + 、Re, Fe 6+ 、Fe 4+ 、Fe 3+ 、Fe 2+ 、Fe + 、Fe, Ru 8+ 、Ru 7+ 、Ru 6+ 、Ru 4+ 、Ru 3+ 、Ru 2+ 、Os 8+ 、Os 7+ 、Os 6+ 、Os 5+ 、Os 4+ 、Os 3+ 、Os 2+ 、Os + 、Os, Co 5+ 、Co 4+ 、Co 3+ 、Co 2+ 、Co + 、Rh 6+ 、Rh 5+ 、Rh 4+ 、Rh 3+ 、Rh 2+ 、Rh+ 、Ir 6+ 、Ir 5+ 、Ir 4+ 、Ir 3+ 、Ir 2+ 、Ir + 、Ir, Ni 3+ 、Ni 2+ 、Ni + 、Ni, Pd 6+ 、Pd 4+ 、Pd 2+ 、Pd + 、Pd, Pt 6+ 、Pt 5+ 、Pt 4+ 、Pt 3+ 、Pt 2+ 、Pt + 、Cu 4+ 、Cu 3+ 、Cu 2+ 、Cu + 、Ag 3+ 、Ag 2+ 、Ag + 、Au 5+ 、Au 4+ 、Au 3+ 、Au 2+ 、Au + 、Zn 2+ 、Zn + 、Zn, Cd 2+ 、Cd + 、Hg 4+ 、Hg 2+ 、Hg + 、B 3+ 、B 2+ 、B + 、Al 3+ 、Al 2+ 、Al + 、Ga 3+ 、Ga 2+ 、Ga + 、In 3+ 、In 2+ 、In 1+ 、Tl 3+ 、Tl + 、Si 4+ 、Si 3+ 、Si 2+ 、Si + 、Ge 4+ 、Ge 3+ 、Ge 2+ 、Ge + 、Ge, Sn 4+, Sn 2+ , Pb 4+ , Pb 2+ , As 5+ , As 3+ , As 2+ , As + , Sb 5+ , Sb 3+ , Bi 5+ , Bi 3+ , Te 6+ , Te 5+ , Te 4+ , Te 2+ , La 3+ , La 2+ , Ce 4+ , Ce 3+ , Ce 2+ , Pr 4+ , Pr 3+ , Pr 2+ , Nd 3+ , Nd 2+ , Sm 3+ , Sm 2+ , Eu 3+ , Eu 2+ , Gd 3+ , Gd 2+ , Gd + , Tb 4+ , Tb 3+ , Tb 2+ , Tb + , Db 3+ , Db 2+ , Ho 3+ , Er 3+ , Tm 4+ , Tm 3+ , Tm 2+ , Yb 3+ , Yb 2+ , Lu 3+ and metal ions selected from the group consisting of these and combinations thereof, and this metal includes any complex containing the metals or metal ions listed above, and any corresponding metal salt to anion, the MOF or composition herein.

[0024] In an embodiment, the present invention provides an MOF or composition herein, wherein the metal is selected from aluminum, titanium, zirconium, and hafnium.

[0025] In one aspect, the present invention provides a method for manufacturing a MOF or a composition herein, the method comprising the step of forming a metal-ligand complex with a linker to form a MOF composition.

[0026] In one aspect, the present invention provides a method for using a MOF or a composition herein, the method comprising the step of absorbing water in the composition.

[0027] The present invention encompasses all combinations of the specific embodiments described herein as if each combination had been described with meticulous care. BRIEF DESCRIPTION OF THE DRAWINGS

[0028]

Figure 1

Figure 2

Figure 3

Figure 4a

Figure 4b

Figure 4c

Figure 4d

Figure 4e

Figure 4f

Figure 4g

Figure 5a

Figure 5b

Figure 5c

Figure 5d

Figure 6a

Figure 6b

Figure 7

Figure 8

Figure 9a

Figure 9b

Figure 9c

Figure 9d

Figure 9e

Figure 9f

Mode for Carrying Out the Invention

[0029] Unless otherwise prohibited or stated, throughout these descriptions and the entire specification, the terms "a" and "an" mean one or more, and the term "or" means and / or. It should be understood that the examples and embodiments described herein are for illustrative purposes only, and various modifications or changes suggested to those skilled in the art should be included within the spirit and scope of this application and within the scope of the appended claims. All publications, patents, and patent applications cited herein, including the cited references therein, are hereby incorporated by reference in their entirety for all purposes.

[0030] Through a two-step procedure using the Wittig reaction followed by hydrolysis, linker L1, an extended version of 1H-3,5-pyrazoledicarboxylic acid (the linker of MOF-303), was synthesized. In an aqueous NaOH solution or a DMF / H 2 O mixture, aluminum salt AlCl 3 ·6H 2 O and linker (L1) were subjected to solvothermal synthesis to obtain MOF-LA2.

[0031] Scheme for L1 synthesis:

[0032] [Chemical formula]

[0033] Scheme for MOF-LA2 synthesis:

[0034] [Chemical formula]

[0035] MOF-LA2 incorporates an isoreticular structure into MOF-303, as shown by its powder X-ray diffraction pattern (PXRD). The water sorption isotherm profile reveals a sharp step at 26% RH, with a total water uptake capacity of 0.63 g / g. This is nearly 1.5 times higher than the total water uptake capacity of MOF-303. Although shifted to the right compared to MOF-303, the water uptake step of MOF-LA2 is still near the RH value corresponding to the conditions in the driest locations in the world.

[0036] The cycling experiment shows that the decrease in the total water absorbency of MOF-LA2 after 29 more cycles is negligible.

[0037] Table 1 shows several linker embodiments with different substituents R for the MOF-LA2 family. The introduction of hydrophilic groups such as -OH and -NH 2 shifts the isotherm to much drier RH values, and the introduction of hydrophobic / neutral groups such as CH 3 or halogen moves the isotherm to higher RH. Another linker embodiment involving variations of the core (X, Y, Z, l) is presented in Table 2.

[0038]

Table 1

[0039]

Table 2

[0040] All of these can be synthesized using the same method as in the case of L1. Similar to MOF-LA2, the test MOF can be obtained via solvothermal synthesis in an aqueous NaOH solution or a DMA / H 2 O mixture. Linkers L1 - L3 (type I linkers) with very similar angles (about 160°) between L1 and the carboxylic acid group form an isoreticular MOF with cis-trans shared AlO 6Connects to MOF-303 showing a chain inorganic building unit (also called secondary building unit SBU; Figure 1). The linker L4 (type II linker) at an angle of about 150° has 4cis-4trans shared AlO 6 Generates a structure similar to that of CAU-23 showing a chain inorganic building unit (Figure 2). Finally, the linkers L5-L9 (type III linkers, about 120°) provide a MOF structure isoreticular to that of CAU-10 presenting a chain inorganic building unit (Figure 3). 6

[0041] Embodiments of longer versions of the L1-L9 linkers giving rise to the MOF-LA4 family are presented in Table 3. Representative examples of novel linkers (n,m-variants) of the MOF-LA5 family are shown in Table 4.

[0042]

Table 3

[0043]

Table 4

[0044] A representative method for synthesizing linkers L10-L18 is shown for L15 and relies on the Knoevenagel condensation of the corresponding bis-aldehyde and malonic acid 13 。

[0045] Scheme for L15 synthesis

[0046]

Chem.

[0047] (Reference 1) TIFF2025516653000010.tif215170

Example

[0048] ​MOF Linker Elongation Strategy for Enhanced Atmospheric Water Harvesting Abstract: A linker elongation strategy for generating metal-organic frameworks (MOFs) with excellent moisture capture properties is presented. By applying a co-design approach that combines experiments and computer processing, it is shown that the water uptake capacity of MOF-LA2-1 {[Al(OH)(PZVDC)], where PZVDC 2- is (E)-5-(2-carboxylatovinyl)-1H-pyrazole-3-carboxylate} is 50% higher than that of the state-of-the-art water harvesting material MOF-303. The power of this approach is to increase the pore volume and enable a decrease in regeneration heat and temperature without compromising the ability of the MOF to harvest water in a dry environment under long-term absorption and desorption cycling. Density functional theory calculations and Monte Carlo simulations provide detailed insights into the framework structure, water interactions within its pores, and the resulting water sorption isotherms.

[0049] Introduction Water stress already affects about half of the world's population. 1,2 Considering the presence of clean water in the atmosphere, porous and hygroscopic sorbents have been investigated for water extraction from air. 33,4 An ideal water harvesting material should (i) take up water at a desired relative humidity (RH), including from desert air, (ii) exhibit a step-shaped hygroscopic behavior to enable the absorption and release of large amounts of water upon slight perturbations in temperature or pressure, (iii) exhibit easy water release to reduce energy consumption and increase productivity, (iv) have hydrothermal stability to enable long-term operation, and (v) be manufactured from abundant and non-toxic components using environmentally friendly processes.

[0050] In this regard, metal-organic frameworks (MOFs) are promising materials as they can be easily designed and modified to achieve the desired properties. 5~7 They have been successful in implementing atmospheric water harvesting. 8~14 In particular, MOF-303 {[Al(OH)(PZDC)], where PZDC 2-is 1H-pyrazole-3,5-dicarboxylate; the discovery of {Figure 4a} represents an important advance towards meeting the above sorbent requirements 11 Specifically, the rod-like secondary building units (SBUs; Figure 4b) of aluminum oxide impart hydrothermal stability to the framework and, together with the aligned PZDC 2- linker, generate pores arranged by alternating hydrophilic-hydrophobic pockets. Single-crystal X-ray diffraction revealed how well-suited these pockets are for the binding of initial water molecules that stimulate the development of the overall water structure 15 .

[0051] The challenge solved by this study is a way to maintain an alternating hydrophilic-hydrophobic pocket environment while simultaneously enhancing the water absorption capacity of the framework. In other words, a way to increase the pore volume of MOF-303 without compromising its favorable water absorption attributes. A common strategy for increasing the pore volume of aluminum MOFs fabricated from rod-like SBUs is linker elongation, which includes polycyclic aromatic linkers or the addition of additional aromatic rings to the linker 16~19 . However, these approaches produce aluminum frameworks that are hydrophobic, low-porosity, or have large pores and are unstable to hydrolysis 16,19,22 .

[0052] Herein, a suitable linker elongation strategy involving the addition of a single vinyl group to PZDC 2- was identified and implemented through an integrated experimental-computational approach (Figure 4a). The corresponding MOF, MOF-LA2-1 {[Al(OH)(PZVDC)], where PZVDC 2- is (E)-5-(2-carboxylatovinyl)-1H-pyrazole-3-carboxylate; Figure 4c}, is isostructural with MOF-303 but has a 50% increase in pore volume and thus water absorption. MOF-LA2-1 shows a slightly shifted step at a higher RH compared to MOF-303 in its isotherm but is still suitable for dry environments. Additionally, this MOF results in a significantly reduced regeneration temperature and enthalpy, as well as high stability during water adsorption-desorption cycling

[0053] Results and Discussion At the beginning of this study, it was hypothesized that adding a long but relatively compact group to the hydrophilic H 2 PZDC linker in MOF-303 would enhance its water uptake capacity while affecting neither its hydrophilicity nor its excellent stability (Figure 4c). In particular, it was desired to retain the arrangement of pyrazole functional groups that serve as primary adsorption sites and are important for its favorable water harvesting properties (Figure 4d). 15 。Density functional theory (DFT) calculations to find a periodic structure consistent with the MOF-303 topology showed that the vinyl addition variant resulted in a favorable increase in pore volume (Section S3.1). In view of the above, H 2 linker H 2 PZVDC featuring vinyl group elongation of H 3 PZDC was synthesized via a two-step procedure using the Wittig reaction of ethyl 5-formyl-1H-pyrazole-3-carboxylate followed by hydrolysis (Section S2). Then, AlCl 2 ·6H 2 O and H 2 PZVDC were used to obtain MOF-LA2-1 by solvothermal synthesis at 120 °C in a DMF / H 2 O (1:4) mixture and further by a green synthesis procedure under reflux and stirring in H

[0054] The as-obtained microcrystalline powder was first characterized by powder X-ray diffraction (PXRD) analysis. A significant 2θ shift to lower values of the corresponding PXRD reflections compared to MOF-303 suggested successful isoreticular expansion of the parent framework (Figure 5a). Additionally, these data were corroborated by the phase purity of the prepared samples by coupling scanning electron microscopy and energy-dispersive X-ray spectroscopy (Section S4). Furthermore, great efforts were made to obtain single crystals suitable for single-crystal X-ray diffraction (SCXRD) analysis of MOF-LA2-1, with dimensions of 10 × 10 × 30 μm 3Crystals were formed. Insights into the unit cell parameters (a = 12.030(12) Å, b = 17.398(17) Å, c = 17.706(17) Å, and β = 99.33(2)°) and SBU stereochemistry were obtained from synchrotron SCXRD data. However, due to substantial intrinsic positional disorder of the asymmetric linker in the crystal structure, the crystallinity of these crystals was relatively low, thus limiting the overall SCXRD data quality and presumably preventing the determination of the exact linker conformation in MOF-LA2-1.

[0055] Therefore, periodic DFT optimization was utilized to explore the relative stability of various possible linker conformations in the MOF-LA2-1 structure with respect to the unit cell parameters extracted from the SCXRD data (Section S3.2). In this context, a total of 16 possible framework conformations were considered, which feature different positions and orientations of the pyrazole and vinyl groups in the hydrophilic cavities of the MOF. In general, conformations where the pyrazole functional groups are on the same side of the pocket (ZUS, derived from the German word “zusammen,” together) were estimated to be more stable than those where the pyrazole moieties are on opposite sides of the pocket (ENT, derived from the German word “entgegen,” opposite). The pyrazole functional groups in the ZUS conformation of MOF-LA2-1 are hypothesized to hydrogen bond with each other and thus stabilize the associated structural arrangement. This is further supported by the fact that the pyrazole moieties are in the same plane in this conformation but not in the ENT conformation. Overall, one ZUS structure (Figure 4e) was identified as particularly stable and thus the most representative conformation of MOF-LA2-1. The next most stable conformation is {asymmetric unit [Al(OH)(PZVDC)] 2 per} 27 kJ mol -1 higher (Section S3.2).

[0056] As mentioned above, MOF-LA2-1 was targeted to enhance its water absorption capacity while retaining the pyrazole functional group arrangement that was determined to be key to the water harvesting properties of MOF-303. H 2Derived from MOF-303 by adding vinyl groups to the PZDC linker molecules. The most stable framework conformation was determined, and the primary water adsorption sites of MOF-LA2-1 in this conformation were investigated computationally and compared with the respective sites of MOF-303 (Figs. 4d, e). Indeed, similar to the primary water adsorption sites of MOF-303, water molecules were adsorbed at sites constituted by the linker pyrazole groups and the μ 2 -OH groups of the aluminum SBUs. The first water molecule was adsorbed through four hydrogen bonds (2.7 - 3.0 Å) to the framework, one each to the N and NH groups of the linker, and two to the μ 2 -OH groups of the aluminum SBU. The second water molecule was adsorbed through two hydrogen bonds (both 2.7 Å), each involving the remaining N and NH groups (Fig. 4e). These water adsorption sites are very similar to those observed in MOF-303 (Fig. 4d), and the first water molecule is adsorbed with comparable strength in MOF-303. The second water molecule is adsorbed more weakly than in MOF-303 (Section S3.3), contributing to a shift of the isotherm to slightly higher RH compared to MOF-303 (see below). Subsequent water molecules are predicted to adsorb to the remaining μ 2 -OH groups of the aluminum SBUs, and additional water molecules are predicted to fill the pores by forming a hydrogen-bond network as previously observed in MOF-303 (Figs. 4f, g) 15 。

[0057] Taking into account the insights obtained from DFT calculations, the structural model of MOF-LA2-1 in its most stable conformation was refined against the experimental PXRD data (Fig. 4e). The framework was modeled in the P2 1 / c space group (No. 14), and the final unit cell parameters were refined to a = 12.1 Å, b = 17.4 Å, c = 17.8 Å, and β = 98.6°, in good agreement with the SCXRD data.

[0058] Next, the thermal stability and porosity of MOF-LA2-1 were investigated using thermogravimetric analysis (TGA) and nitrogen sorption analysis, respectively. TGA under both argon and air atmospheres revealed no significant mass loss below 300 °C, indicating excellent stability required for thermal regeneration during the water harvesting operation. The initial evaluation of the nitrogen sorption isotherm of MOF-LA2-1 at 77 K showed a Brunauer-Emmett-Teller (BET) surface area of 1892 m 2 g -1 respectively, and a pore volume of 0.67 cm 3 g -1 respectively, which was 1.4 times higher than that of MOF-303 15 .

[0059] The water harvesting properties of MOF-LA2-1 were first explored by performing water sorption measurements under isothermal conditions. Similar to the parent framework, the extended framework is likely related to the presence of hydrophilic pockets formed by pyrazole functional groups, as previously observed in MOF-303, and thus presented a steep step in its isotherm, forming strong water adsorption sites 15 . Notably, the water sorption isotherm profile showed a sharp step at 26% RH, with a total water uptake of 0.64 g g -1 respectively, which was 50% higher in water capacity than MOF-303 (Figure 5b). Although the step position of MOF-LA2-1 shifted to a slightly higher RH value compared to MOF-303, it was still suitable for water harvesting in the driest regions around the world 23,24 . Furthermore, water sorption analysis was performed at various temperatures, and these data were used to evaluate the isosteric heat of water adsorption Q st using the Clausius-Clapeyron relationship. MOF-LA2-1 showed an average Q -1 value of 50 kJ mol st and was found to be a total reduction of 4 kJ mol -1 compared to its parent framework evaluated under similar conditions 25 . The heat of condensation of water (44 kJ mol at 25 °C -1) Considering this, it is similar to the heat of adsorption penalty being 40% lower than that of MOF-303. Importantly, it is recognized that the favorable water sorption properties of MOF-LA2-1 were not impaired when a green reflux-based synthesis was used for its preparation.

[0060] Furthermore, the regeneration temperature of MOF-LA2-1 was explored by measuring the isobaric desorption curves. These measurements were carried out at water vapor pressures of 1.27 and 1.70 kPa (corresponding to 30 and 40% RH at 30 °C respectively), demonstrating that the water release temperature was substantially reduced compared to MOF-303 (Figure 5c), thus enabling the operating desorption temperature to be a very desirable 45 °C. Together with the significantly reduced isosteric heat of adsorption, these findings embody MOF-LA2-1 as an energy-efficient water harvesting material for the dry region.

[0061] To test the stability of MOF-LA2-1 under operating conditions, temperature swing adsorption-desorption cycling was performed at a water vapor pressure of 1.70 kPa (Figure 5d). From this experiment, a 5% decrease in the water uptake capacity was shown after 75 cycles and a further 1% decrease after an additional 75 cycles, thus indicating a plateau state in the capacity loss of MOF-LA2-1 and overall good longevity.

[0062] Next, the dependence of the water adsorption behavior of MOF-LA2-1 on different linker conformations was investigated. For this purpose, force field-based Monte Carlo simulations in the Gibbs ensemble were used to computationally treat the water adsorption isotherms at 298 K (Section S3.4). These efforts focused on the most stable ZUS and ENT conformations that serve as representative examples of various structural ensembles (Section S3.4). The simulated water sorption isotherms for the two structure types exhibited significantly different profiles (Figures 6a–b). In good agreement with the measured adsorption isotherms, the ZUS conformation showed an initial water uptake of about five water molecules per unit cell consisting of four asymmetric units at 5% RH and a sharp isotherm step at 30% RH. In contrast, the computationally treated isotherm of the ENT conformation of MOF-LA2-1 showed a more gradual profile, which could be explained by more water adsorption sites and pore walls with varying binding strengths. Based on the comparison with the experimental water sorption isotherms, it can be concluded that the isotherm of the ZUS conformation better represents the experimental data and thus further supports our structural model (Figure 4e).

[0063] In conclusion, the linker “arm” elongation strategy was demonstrated and utilized to greatly improve the water harvesting properties of the state-of-the-art water harvesting material MOF-303. Importantly, this features a 50% increase in water uptake capacity and a reduction in the requirements regarding operating energy while maintaining the ability to capture moisture in the dry region and the hydrothermal stability suitable for long-term absorption and desorption cycling. This approach can be generalized and is particularly useful for commercially important aluminum-based MOFs.

[0064] Section S2. Synthesis procedure (E)-5-(2-Carboxyvinyl)-1H-pyrazole-3-carboxylic acid (H 2 PZVDC) synthesis:

[0065]

Chemical formula

[0066] Step 1: 13 Into a 100 mL round-bottom flask equipped with a stir bar, 1 (1.5 g, 8.9 mmol, 1 equiv) and dry THF (50 mL) were charged under an argon atmosphere. Using an acetone / ice bath, the mixture was cooled to -10 °C, and 2 (3.5 g, 10.5 mmol, 1.2 equiv) was added portionwise. The reaction was allowed to warm to room temperature overnight. After the resulting solution was concentrated under reduced pressure, the mixture containing the E- and Z-isomers was identified via 1 H NMR analysis. The desired E-isomer 3 was isolated via column chromatography using acetone / hexane (5 / 1) as the eluent (R f = 0.1). Yield: 1.3 g, 65%. 1 H NMR (400 MHz, CDCl 3 ) δ 10.93 (s, 1H), 7.67 (d, J = 16.0 Hz, 1H), 7.04 (s, 1H), 6.48 (d, J = 16.0 Hz, 1H), 4.41 (q, J = 7.1 Hz, 2H), 3.81 (s, 3H), 1.41 (t, J = 7.1 Hz, 3H) ppm.

[0067] Step 2: Into a 100 mL round-bottom flask equipped with a stir bar, 3 (1.3 g, 5.8 mmol, 1 equiv), MeOH (50 mL) and an aqueous NaOH solution (20 mL, 1.5 M, 5 equiv) were charged. The reaction was monitored by TLC and heated at 50 °C (oil bath temperature) until the starting material was consumed (2 h). The solution was concentrated under reduced pressure, and 5 M HCl was added dropwise until pH = 2 - 3. The resulting precipitate was filtered off and washed thoroughly with H 2 O (4 × 10 mL) and MeOH (1 × 5 mL). After drying in vacuo at 50 °C, the linker H 2 PZVDC was obtained as a white powder. Yield: 1.0 g, 95%. 1 H NMR (500 MHz, DMSO-d 6 ) δ 13.80 - 13.10 (br. s, 3H), 7.46 (d, J = 16.2 Hz, 1H), 7.17 (s, 1H), 6.53 (d, J = 16.1 Hz, 1H). 1313C NMR (126 MHz, DMSO-d 6 ) ppm. δ 167.4, 161.4, 120.6, 108.4 ppm. HRMS (m / z): C 7 H 5 N 2 O 4 [M-H] - calculated value 181.0255; measured value 181.0255.

[0068] Solvothermal synthesis of MOF-LA2-1:

[0069]

Chem.

[0070] In a 4 mL scintillation vial, the linker H 2 PZVDC (91.0 mg, 0.5 mmol, 1 equiv) was sonicated and dissolved in N,N-dimethylformamide (DMF) (0.6 mL). An aqueous solution of AlCl 3 ·6H 2 O (2.4 mL, 0.2 M, 1 equiv) was added dropwise, and the resulting mixture was heated in an oven at 120 °C for 24 h. After cooling to room temperature, the white precipitate was collected by centrifugation and washed with H 2 O (3×30 mL) and MeOH (3×30 mL). MOF-LA2-1 was activated under dynamic vacuum (ca. 10 -3 mbar) at room temperature for 12 h and then gently heated to 120 °C for 6.5 h. Yield: 65.0 mg, 58%. Elemental analysis of MOF-LA2-1: C 56 H 40 N 16 O 40 Al 8 calculated values: C, 37.52; H, 2.25; N, 12.50%. Measured values: C, 36.78; H, 2.38; N, 11.95%.

[0071] Green synthesis of MOF-LA2-1:

[0072]

Chem.

[0073] Into a 50 mL round-bottom flask, linker H 2 PZVDC (364 mg, 2 mmol, 1 equiv) and NaOH (160 mg, 4 mmol, 2 equiv) were sonicated and dissolved in deionized water (10 mL). AlCl 3 ·6H 2 O aqueous solution (6 mL, 0.33 M, 1 equiv) was added dropwise over 10 minutes, and the resulting mixture was heated to 120 °C and refluxed for 2 hours. After cooling to room temperature, the white powder was recovered by centrifugation and washed with deionized water (2 × 10 mL) and EtOH (3 × 10 mL). The white powder was dried overnight under air and then activated at 120 °C for 12 hours under dynamic vacuum (ca. 10 -3 mbar). Yield: 301 mg, 66%. Elemental analysis of MOF-LA2-1: C 56 H 40 N 16 O 40 Al 8 Calculated values for C, 37.52; H, 2.25; N, 12.50%. Found: C, 37.29; H, 2.43; N, 12.10%.

[0074] Section S3. Computational study of MOF-LA2-1 Section S3.1. Initial prediction of pore volume and water adsorption properties First, from the parent MOF-303, a hypothetical MOF of MOF-LA2-1 was constructed by replacing the PZDC 2- (1H-pyrazole-3,5-dicarboxylate) linker of MOF-303 with a PZVDC 2- linker containing an extension by a vinyl group. Without any a priori knowledge of the experimental crystal structure of this MOF, a DFT-optimized structure of this MOF was constructed in which the contact angle of the aluminum oxide rod and the linker resembles that in MOF-303 containing pyrazole groups that form an alternating pattern of hydrophilic-hydrophobic pockets. In this arrangement, the vinyl group extension enabled an increase in pore volume of more than 30% compared to the parent MOF (0.598 cm 3 g -1For 0.452 cm 3 g -1 ). The water adsorption isotherm of MOF-LA2-1 at 298 K was predicted using a force-field-based Monte Carlo simulation in the NpT-ensemble (see Section S1, and more specifically the computer processing method). The simulated adsorption isotherm showed a sharp step at about 18% relative humidity and 0.6 g g -1 of total water uptake, but was a 1.5-fold increase compared to the MOF-303 absorption predicted using the same procedure.

[0075] Section S3.2. Stability of different linker conformations in MOF-LA2-1 DFT calculations were utilized to explore the relative stability of different possible linker conformations in the MOF-LA2-1 structure. A total of 16 different linker conformations (Figure 8) with different positions and orientations of the pyrazole and vinyl groups in the hydrophilic cavities of the MOF were considered. The four-part labeling rule was used for these different linker conformations, which were drawn such that the wide side of the pocket was on the left for the purpose of classification, and the symmetrically equivalent μ 2 -OH groups (labeled 2; Figure 7) were on the left and right sides of the bottom of the pocket. The first part of the naming rule indicates whether the pyrazole group derived from the inverse linker in the hydrophilic pocket of the MOF is present on the side of the cavity {represented as ZUS (derived from the German word "zusammen", together)} or on the alternating side {represented as ENT (derived from the German word "entgegen", opposite)}. The second part of the naming rule indicates whether the pyrazole ring at the top of the cutaway view is located on the wide (represented as w) side or the narrow (represented as n) side of the pocket. Finally, the geometry of the vinyl group with respect to the corresponding pyrazole ring is reflected via a cis / trans notation starting with the upper linker.

[0076] The relative stability of various linker conformations was evaluated using periodic DFT optimization of the framework atoms of the empty MOF constrained by the experimentally determined lattice parameters (theoretical PBE-D3 / 850 eV level, see Section S1, Computational Methods for more details). In general, the ZUS linker conformation in which pyrazole groups face each other in the hydrophilic cavity of the MOF was found to be more stable than the ENT linker conformation, which may be due to the potential hydrogen bond stabilization between the facing pyrazole groups in the ZUS linker conformation. Furthermore, the ZUS linker conformation {ZUS(w)} in which the pyrazole groups are present on the wider side of the hydrophilic cavity was found to be more stable than the linker conformation {ZUS(n)} in which the pyrazole groups are present on the narrower side of the hydrophilic pocket. This can be explained by the potential steric hindrance associated with the relatively large pyrazole moieties present on the narrower side of the pocket. In contrast to the ZUS linker conformation in which the pyrazole groups are aligned in the same plane in the hydrophilic MOF cavity, the pyrazole groups in the hydrophilic cavity of the MOF with the ENT linker conformation were not aligned in a common plane. The orientation of the vinyl groups was also found to affect the relative stability of the MOF-LA2-1 structure. In general, the presence of the cis-oriented vinyl group with respect to pyrazole in the ZUS(w) conformation destabilized the MOF structure. In contrast, the ZUS(n) conformation was stabilized by the presence of the cis-oriented vinyl group.

[0077] In summary, the ZUS(w)-trans,trans linker arrangement was found to be the most stable conformation of MOF-LA2-1. The other four linker conformations (i.e., ZUS(n)-cis,trans; ENT(w)-trans,cis; ZUS(w)-trans,cis; and ZUS(w)-cis,trans) were identified as energetically accessible linker conformations {asymmetric unit [Al(OH)(PZVDC)] 2 per 27 - 29 kJ·mol -1 of ΔE value, i.e., about 4 k BT}. The first four structures were used as representative structures to investigate the water adsorption behavior in MOF-LA2-1. For ZUS(w)-cis,trans, calculations were not performed due to its similarity to ZUS(w)-trans,cis.

[0078] Section S3.3. Determination of the primary water adsorption sites MOF-LA2-1 was targeted to enhance the water absorption capacity of MOF-303 while retaining the arrangement of the pyrazole functional groups, which were judged to be the key to the favorable water harvesting properties of MOF-303, of the PZDC 2- linker of MOF-303 by adding a compact yet long vinyl group. To demonstrate this, the primary water adsorption sites in the ZUS(w)-trans,trans and ENT(w)-trans,cis linker configurations of MOF-LA2-1, which serve as representative structures of the ZUS and ENT configurations, were investigated. Indeed, as in the case of the primary water adsorption sites previously determined in MOF-303 (Figs. 9a, b), in both linker configurations, water molecules are adsorbed at sites constituted by the pyrazole moiety and the μ 2 -OH groups of the aluminum oxide rods.

[0079] In the ZUS(w)-trans,trans linker configuration, the first water molecule forms four H-bonds (2.7 - 3.0 Å) with the framework. One is with the NH and N groups of two adjacent linkers respectively, and two are with the μ 2 -OH groups of the aluminum oxide rods (ΔE ads,avg = -84.6 kJ mol -1 ; Fig. 9c). The second water molecule adsorbs through two H-bonds (2.6 and 2.8 Å). These are one each with the NH and N groups of the remaining adjacent pyrazole moieties (ΔE ads,avg = -57.7 kJ mol -1 ; Fig. 9d). These water adsorption sites are similar to those observed in MOF-303, and the first H 2 O molecule adsorbs with comparable strength, and the second H 2O molecules adsorb more strongly than MOF-LA2-1 {Δ Eads,avg = one and two H per asymmetric unit [Al(OH)(PZDC)] 2 O molecules at -82.4 and -80.2 kJ mol 2 ; Figures 9a, b}. Subsequent water molecules are expected to adsorb to the remaining μ -1 -OH groups of the Al oxide rods, as previously observed for MOF-303 2 . 1

[0080] In contrast, the H 2 O adsorption sites have different ENT(l)-trans,cis linker conformations, which can be explained by the spatial separation of the pyrazole groups. The first H 2 O molecule adsorbs through four H-bonds (2.7–2.9 Å) to the framework. One is to the NH group, two are to the μ 2 -OH groups, and one is to the carboxylate group of the linker (Δ Eads,avr = -77.4 kJ mol -1 , Figure 9e). The second H 2 O molecule adsorbs through two H-bonds (2.7 Å and 3.0 Å). One is to the NH group and the other is to the μ 2 -OH group of the Al oxide rod (Δ Eads,avg = -63.9 kJ mol - -1, Figure 9f). In this linker conformation, the N groups of the linker can adsorb subsequent water molecules, thereby increasing the number of favorable sites for H 2 O adsorption compared to MOF-303.

[0081] Section S3.4. Simulation of water adsorption isotherms ​Next, the dependence of the water adsorption behavior of MOF-LA2-1 on different linker conformations was explored. Computerized water adsorption isotherms at 298 K were generated using force-field-based Monte Carlo (MC) simulations in the isobaric-isothermal (NpT) Gibbs ensemble. Considering the similarity of the primary adsorption sites of MOF-LA2-1 and MOF-303 (Section S3.3), the simulation settings were chosen to be the same as those in previous studies focused on predicting the water adsorption isotherm of MOF-303 (for details, see Section S1, the computerized method). 2 Four H 2 O molecules per unit cell (equivalent to 1 H 2 O per asymmetric unit), which were removed prior to the MC simulation, were used to perform these calculations using the rigid framework structure of MOF-LA2-1 optimized in the presence of these molecules. This arrangement expanded the hydrophilic cavities and thus realized the structural flexibility of the MOF, which has previously been shown to be important for obtaining appropriate initial water uptake in MOF-303 2 .

[0082] Using the above procedure, the water adsorption isotherms of MOF-LA2-1 with ZUS(w)-trans,trans; ZUS(n)-cis,trans; ZUS(w)-trans,cis; and ENT(w)-trans,cis linker configurations were simulated. It should be noted that the ZUS and ENT linker configurations exhibit significantly different water adsorption behaviors. Consistent with the measured adsorption isotherms, both ZUS(w)-trans,trans and ZUS(w)-trans,cis configurations, where the pyrazole group is on the wider side of the hydrophilic cavity, show an initial water uptake of approximately 5 water molecules per unit cell already at 5% relative humidity (RH), shifted slightly compared to the experimental isotherm, and showing a sharp step in the isotherm step at approximately 30% RH. Since these two linker configurations differ only in the orientation of the vinyl group and their adsorption behaviors are similar, it is suggested that the orientation (cis or trans) of the vinyl group does not significantly affect the overall adsorption isotherm. On the other hand, the ZUS(n)-cis,trans linker configuration, where the pyrazole group is on the narrower side of the hydrophilic cavity, does not show the initial water uptake at RH below 10% observed in the experimental isotherm, despite the fact that the framework structure used for this linker configuration is optimized in the presence of 4 H 2 O molecules per unit cell. This is consistent with the observation that water molecules did not adsorb at "strong" adsorption sites during DFT optimization, as observed for other ZUS linker configurations. Instead, the adsorbed water molecules move from the plane of the two pyrazole linkers into the MOF pores, thereby not significantly expanding the cavity upon water adsorption. This linker configuration exhibits a sharp step in the isotherm at approximately 22% RH and thus shows a larger deviation from the experimental isotherm than the ZUS(w) configurations.

[0083] In contrast to the sharp steps observed in the adsorption isotherms of the three ZUS linker conformations investigated, the water uptake in the ENT(w)-trans,cis linker conformation increased more gradually. The pyrazole functional groups are dispersed throughout the hydrophilic cavities, resulting in a larger number of energetically favorable adsorption sites within the framework compared to the ZUS linker conformations. Considering the steep profile of the experimental isotherm, it can be concluded that the ENT linker conformation is not a suitable structural model, while the ZUS(w)-trans,trans and ZUS(w)-trans,cis linker conformations appear to be excellent representatives of the synthesized MOF-LA2-1.

[0084]

Table 5

[0085] References and Supplementary References for Examples (Reference 2) TIFF2025516653000015.tif231170TIFF2025516653000016.tif228170TIFF2025516653000017.tif188170

Claims

1. A metal-organic framework (MOF) composition, having the following formula: 【Chemical Formula 1】 [wherein, X, Y, and Z are independently C(H), N(H), O, or S, R 1 ~R 5 are independently CH 3 , NH 2 , OH, halogen or H, and m is an integer from 0 to 5, n is an integer from 1 to 5, l is an integer of 1 or 2, b1 and b2 are independently a single bond or a double bond, and at least one b2 is a double bond] The MOF composition comprising a metal complexed with an organic linker.

2. The metal-organic framework (MOF) comprises a repeating core, the core comprises secondary building units linked to an organic ligand (linker), the secondary building units comprise one or more metals or metal-containing complexes, and the secondary building units are linked to the organic ligand via oxygen atoms of carboxylate groups in the organic ligand (linker), The MOF composition according to claim 1.

3. R 1 ~R 5 The MOF composition according to claim 1, wherein R to R are H.

4. R 1 ~R 5 1, 2, 3, 4 or 5 of 3 , N.H. 2 , OH or halogen, and the others are H.

5. m is 0, 1, or 2, n is 1, 2, or 3, or m is 0, 1, or 2, n is 1 or 2, The MOF composition according to claim 1.

6. m is 0 and n is 1, m is 0 and n is 2, m is 1 and n is 1, m is 1 and n is 2, m is 1 and n is 3, m is 2 and n is 2, m is 2 and n is 3, or m is 3 and n is 3, The MOF composition according to claim 1.

7. l is 1, The MOF composition according to claim 1.

8. One, two, or three of X, Y, and Z are independently N(H), O, or S, The MOF composition according to claim 1.

9. X and Y are N and NH respectively, and Z is C, The MOF composition according to claim 1.

10. The linker has the formula II: 【Chemical 2】 [wherein, R 1 is H, NH 2 or OH, and R 2 is H, NH 2 or OH, and R 3 is H, NH 2 or OH] The MOF composition according to any one of claims 1 to 9.

11. The linker contains the formulae of Table 1, 2, 3, or 4 (Table 1, 2, 3, or 4), The MOF composition according to any one of claims 1 to 9.

12. The metal is Li + 、Na + 、K + 、Rb + 、Cs + 、Be 2+ 、Mg 2+ 、Ca 2+ 、Sr 2+ 、Ba 2+ 、Sc 3+ 、Sc 2+ 、Sc + 、Y 3+ 、Y 2+ 、Y + 、Ti 4+ 、Ti 3+ 、Ti 2+ 、Zr 4+ 、Zr 3+ 、Zr 2+ 、Hf 4+ 、Hf 3+ 、V 5+ 、V 4+ 、V 3+ 、V 2+ 、Nb 5+ 、Nb 4+ 、Nb 3+ 、Nb 2+ 、Ta 5+ 、Ta 4+ 、Ta 3+ 、Ta 2+ 、Cr 6+ 、Cr 5+ 、Cr 4+ 、Cr 3+ 、Cr 2+ 、Cr + 、Cr, Mo 6+ 、Mo 5+ 、Mo 4+ 、Mo 3+ 、Mo 2+ 、Mo + 、Mo, W 6+ 、W 5+ 、W 4+ 、W 3+ 、W 2+ 、W + 、W, Mn 7+ 、Mn 6+ 、Mn 5+ 、Mn 4+ 、Mn 3+ 、Mn 2+ 、Mn + 、Re 7+ 、Re 6+ 、Re 5+ 、Re 4+ 、Re 3+ 、Re 2+ 、Re + 、Re, Fe 6+ 、Fe 4+ 、Fe 3+ 、Fe 2+ 、Fe + 、Fe, Ru 8+ 、Ru 7+ 、Ru 6+ 、Ru 4+ 、Ru 3+ 、Ru 2+ 、Os 8+ 、Os 7+ 、Os 6+ 、Os 5+ 、Os 4+ 、Os 3+ 、Os 2+ 、Os + 、Os, Co 5+ 、Co 4+ 、Co 3+ 、Co 2+ 、Co + 、Rh 6+ 、Rh 5+ 、Rh 4+ 、Rh 3+ 、Rh 2+ 、Rh + 、Ir 6+ 、Ir 5+ 、Ir 4+ 、Ir 3+ 、Ir 2+ 、Ir + 、Ir, Ni 3+ 、Ni 2+ 、Ni + 、Ni, Pd 6+ 、Pd 4+ 、Pd 2+ 、Pd + 、Pd, Pt 6+ 、Pt 5+ 、Pt 4+ 、Pt 3+ 、Pt 2+ 、Pt + 、Cu 4+ 、Cu 3+ 、Cu 2+ 、Cu + 、Ag 3+ 、Ag 2+ 、Ag + 、Au 5+ 、Au 4+ 、Au 3+ 、Au 2+ 、Au + 、Zn 2+ 、Zn + 、Zn, Cd 2+ 、Cd + 、Hg 4+ 、Hg 2+ 、Hg + 、B 3+ 、B 2+ 、B + 、Al 3+ 、Al 2+ 、Al + 、Ga 3+ 、Ga 2+ 、Ga + 、In 3+ 、In 2+ 、In 1+ 、Tl 3+ 、Tl + 、Si 4+ 、Si 3+ 、Si 2+ 、Si + 、Ge 4+ 、Ge 3+ 、Ge 2+ 、Ge + 、Ge, Sn 4+ 、Sn 2+ 、Pb 4+ 、Pb 2+ 、As 5+ 、As 3+ 、As 2+ 、As + 、Sb 5+ 、Sb 3+ 、Bi 5+ 、Bi 3+ 、Te 6+ 、Te 5+ 、Te 4+ 、Te 2+ 、La 3+ 、La 2+ 、Ce 4+ 、Ce 3+ 、Ce 2+ 、Pr 4+ 、Pr 3+ 、Pr 2+ 、Nd 3+ 、Nd 2+ 、Sm 3+ 、Sm 2+ 、Eu 3+ 、Eu 2+ 、Gd 3+ 、Gd 2+ 、Gd + 、Tb 4+ 、Tb 3+ 、Tb 2+ 、Tb + 、Db 3+ 、Db 2+ 、Ho 3+ 、Er 3+ 、Tm 4+ 、Tm 3+ 、Tm 2+ 、Yb 3+ 、Yb 2+ 、Lu 3+ 、and metal ions selected from combinations thereof, and any complex containing the metals or metal ions listed above, and any corresponding metal salt to anion are also included, the MOF composition according to any one of claims 1 to 9.

13. The metal is selected from aluminum, titanium, zirconium, and hafnium, The MOF composition according to any one of claims 1 to 9.

14. A method for producing the MOF composition according to claim 1, comprising the step of complexing a metal with a linker to form the MOF composition.

15. A method of using the MOF composition according to claim 1, the method comprising the step of absorbing water in the composition.

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