Crystal and method for producing same

Abstract

A crystal according to the present invention is formed as a result of the accumulation of a host-guest complex constituted by: a host molecule that has an opening and an internal space and that has a three-fold rotation axis, a four-fold rotation axis, or a six-fold rotation axis; and a guest molecule accommodated in the internal space of the host molecule. When visualizing a rectangular parallelepiped in which the lengths of three sides are a, b, and c (where a ≥ b ≥ c) can accommodate the crystal, a would be 1 mm or more, b would be 1 mm or more, and c would be 0.05 mm or more in a rectangular parallelepiped having the minimum capacity. A method for producing a crystal according to the present invention is characterized in that a solution containing host molecules and guest molecules is left to stand.

Description

Crystals and their manufacturing method

[0001] The present invention relates to high-purity, large crystals of a host-guest complex and a method for producing the same.

[0002] Some host-guest complexes have attracted attention as raw materials for various elements such as photoelectric elements, thermoelectric elements, etc. For this reason, in recent years, measurements of the physical properties of solid-state host-guest complexes have been carried out, and the molecular structures of host-guest complexes have been elucidated by single crystal structure analysis.

[0003] For example, Patent Document 1 describes a crystalline material consisting of an inclusion complex in which a dye having a π-plane serves as a guest molecule and cyclodextrin or a derivative thereof serves as a host molecule. Patent Document 1 also describes the polarization and fluorescence properties of the obtained crystalline material, as well as the molecular structure revealed by single crystal structure analysis.

[0004] In relation to the present invention, the present inventors have reported the physical properties and molecular structure of a host-guest complex formed by the inclusion of adamantane in the internal space of (P)-(9,6)-[3]cyclodibenzochrysenylene (Non-Patent Documents 1 and 2).

[0005] JP 2012-92229 A

[0006] Angew. Chem. Int. Ed. 58, 7385-7389 (2019) Nat. Commun. 12,5062 (2021)

[0007] As described in Patent Document 1 and Non-Patent Document 2, single crystals of host-guest complexes have been obtained. However, these single crystals are measurement samples for X-ray crystal structure analysis, and their size is usually about 100 μm × 100 μm × 100 μm. For this reason, the single crystals disclosed in these documents are not suitable as raw materials for various elements. In other words, when a single crystal is molded directly to produce an element, a larger crystal is required. Furthermore, when a single crystal is crushed and then molded to produce an element, a larger crystal is preferable in consideration of mass productivity and the inclusion of impurities.

[0008] The present invention has been made under these circumstances, and an object of the present invention is to provide high-purity, large crystals of a host-guest complex and a method for producing the same.

[0009] In order to solve the above problems, the present inventors have conducted extensive research into crystals of host-guest complexes and methods for producing the same. As a result, they have found that because molecules with specific rotational symmetry have excellent planar packing properties, host-guest complexes containing such molecules as host molecules tend to align in a plane and easily form two-dimensional sheet-like assemblies (single-layer assemblies of host-guest complexes aligned in a plane), and that by forming these two-dimensional sheet-like assemblies into multiple layers, high-purity, large crystals can be obtained, which led to the completion of the present invention.

[0010] Thus, according to the present invention, there are provided the following crystals [1] to

[14] and a method for producing the crystal

[15] .

[0011] [1] A crystal formed by the accumulation of host-guest complexes, the host-guest complex being composed of a host molecule having an internal space and an opening, and a guest molecule accommodated in the internal space of the host molecule, the host molecule being a molecule having a three-fold rotation axis, a four-fold rotation axis, or a six-fold rotation axis, and when a rectangular parallelepiped having three side lengths a, b, and c (where a≧b≧c) that can accommodate the crystal is imagined, the rectangular parallelepiped having the smallest volume has a of 1 mm or more, b of 1 mm or more, and c of 0.05 mm or more. [2] The crystal according to [1], wherein when the largest circle that can fit into the opening of the host molecule is imagined, the diameter of the circle is 0.7 to 1.7 nm. [3] The crystal according to [1] or [2], wherein the host molecule is a molecule having chirality, and the host molecule contained in the crystal is one of the enantiomers. [4] The crystal according to any of [1] to [3], wherein the host molecule is a molecule composed of a non-metallic element. [5] The crystal according to any one of [1] to [4], wherein the host molecule is a tubular molecule having openings at both ends. [6] The crystal according to [5], wherein the host molecule is a molecule represented by the following formula (I):

[0012]

[0013] [In formula (I), A represents a group having a fused ring structure, and n is 3, 4, or 6.] [7] The crystal according to [6], wherein A is a group having a partial structure represented by the following formula (II):

[0014]

[0015] [In formula (II), * represents a bond.] [8] The crystal according to [7], wherein A is a group represented by the following formula (III):

[0016]

[0017] [In formula (III), R １ , R ２ each independently represent a hydrogen atom, a halogen atom, or an unsubstituted or substituted hydrocarbon group having 1 to 20 carbon atoms. * represents a bond.] [9] The crystal according to any one of [1] to [8], wherein the guest molecule is a molecule having 1 to 200 atoms constituting the guest molecule (excluding the number of hydrogen atoms).

[10] The crystal according to any one of [1] to [9], wherein the guest molecule is a molecule having a ring structure.

[11] The crystal according to any one of [1] to

[10] , wherein the guest molecule is rotated within the internal space of the host molecule.

[12] The crystal according to any one of [1] to

[11] , wherein CH-π interaction and / or π-π interaction exists between adjacent host-guest complexes.

[13] The crystal according to any one of [1] to

[12] , wherein the crystal comprises a two-dimensional sheet-like assembly formed by the host-guest complexes.

[14] The crystal according to

[13] , wherein the crystal is formed by multilayering the two-dimensional sheet-like assemblies.

[15] A method for producing the crystal according to any one of [1] to

[14] , comprising allowing a solution containing a host molecule and 1 to 10,000 equivalents of a guest molecule relative to the host molecule to stand.

[0018] According to the present invention, there are provided high-purity, large crystals of a host-guest complex and a method for producing the same.

[0019] 1 is a photograph of the crystal obtained in Example 1. FIG. 2 is a photograph of the crystal obtained in Example 1. FIG. 3 is a photograph of the crystal obtained in Example 1. FIG. 4 is a diagram showing the molecular structure of the host-guest complex constituting the crystal obtained in Example 1. FIG. 5 is a diagram showing the molecular structure of the host-guest complex constituting the crystal obtained in Example 1. d regarding the host-guest complex constituting the crystal obtained in Example 1 ｅ 1 is a Hirshfeld map showing the results of AIM analysis of the host-guest complex constituting the crystal obtained in Example 1.

[0020] The present invention will be described in detail below, divided into the following sections: 1) crystals, and 2) methods for producing crystals.

[0021] 1) Crystal The crystal of the present invention is a crystal formed by the accumulation of a host-guest complex. The host-guest complex is composed of a host molecule having an internal space and an opening, and a guest molecule accommodated in the internal space of the host molecule. The host molecule is a molecule having a three-fold rotation axis, a four-fold rotation axis, or a six-fold rotation axis. Furthermore, when a rectangular parallelepiped having three side lengths a, b, and c (where a≧b≧c) that can accommodate the crystal is imagined, the rectangular parallelepiped with the smallest volume has a of 1 mm or more, b of 1 mm or more, and c of 0.05 mm or more.

[0022] [Host Molecule] The host molecule that constitutes the host-guest complex is a molecule that has an internal space and an opening.

[0023] The internal space of the host molecule is a space that can accommodate a guest molecule. The shape of the internal space of the host molecule is not limited as long as it can accommodate a guest molecule. The shape of the internal space of the host molecule may be elongated, for example, like a "pore."

[0024] The opening of the host molecule is the entrance to the internal space of the host molecule. The guest molecule passes through the opening of the host molecule and enters the internal space of the host molecule. The size of the opening of the host molecule is not limited as long as the guest molecule can pass through. When the largest circle that can fit into the opening of the host molecule is imagined, the diameter of this circle is preferably 0.7 to 1.7 nm, more preferably 0.9 to 1.5 nm. The diameter of the largest circle that can fit into the opening of the host molecule can be determined based on crystal structure analysis data.

[0025] The host molecule is a molecule having a three-fold, four-fold, or six-fold rotation axis. Molecules having a three-fold, four-fold, or six-fold rotation axis have excellent planar packing properties. Therefore, by using a molecule having these rotation axes as a host molecule, it becomes easier to obtain crystals containing two-dimensional sheet-like assemblies formed by a host-guest complex. Crystals containing such two-dimensional sheet-like assemblies tend to have the characteristic that their purity is less likely to decrease even when grown large.

[0026] The host molecule is preferably a molecule having chirality, and the host molecule contained in the crystal is preferably one of the enantiomers. When the host molecule contained in the crystal is one of the enantiomers, if the guest molecule is a molecule having chirality, one of the enantiomers may be preferentially incorporated.

[0027] The host molecule is preferably a molecule composed of non-metallic elements, such as hydrogen, carbon, nitrogen, phosphorus, oxygen, sulfur, fluorine, chlorine, bromine, and iodine.

[0028] In recent years, metal-organic frameworks (MOFs) have attracted attention as functional materials. Research on MOFs has led to the creation of a wide variety of molecules by utilizing the bonds between transition metal ions and ligands. However, some MOFs contain rare metals as essential components, and using such MOFs as raw materials for various devices poses challenges in terms of economic efficiency and mass production. In this regard, host molecules composed of nonmetallic elements are more suitable as raw materials for various devices.

[0029] The host molecule is preferably a cylindrical molecule having openings at both ends. When the host molecule has such a shape, the host-guest complex is rapidly formed in the crystal production process, and high-purity, large crystals can be efficiently produced. Furthermore, when the host molecule is a cylindrical molecule, the rotational movement of the guest molecule within the internal space of the host molecule may be promoted.

[0030] The cylindrical molecule may be a molecule represented by the following formula (I):

[0031]

[0032] In formula (I), A represents a group having a fused ring structure. n is 3, 4, or 6. When a tubular molecule in which A is a group having a fused ring structure is used as a host molecule, CH-π interactions and π-π interactions are likely to occur between the host-guest complexes in the crystal, as will be described later. Examples of A in formula (I) include groups having a partial structure represented by the following formula (II):

[0033]

[0034] In formula (II), * represents a bond. When a tubular molecule in which A is a group having a partial structure represented by formula (II) is used as a host molecule, a host-guest complex is easily formed in which the guest molecule rotates at high speed within the internal space of the host molecule. Examples of groups having a partial structure represented by formula (II) include groups represented by the following formula (III):

[0035]

[0036] In formula (III), R １ , R ２ each independently represents a hydrogen atom, a halogen atom, or an unsubstituted or substituted hydrocarbon group having 1 to 20 carbon atoms. * represents a bond. The number of carbon atoms in the unsubstituted or substituted hydrocarbon group (excluding the number of carbon atoms in the substituent) is 1 to 20, preferably 2 to 15, and more preferably 3 to 10.

[0037] R １ , R ２Examples of the halogen atom include a fluorine atom, a chlorine atom, and a bromine atom.

[0038] R １ , R ２ Examples of the unsubstituted hydrocarbon groups having 1 to 20 carbon atoms include: unsubstituted alkyl groups having 1 to 20 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, and n-decyl; unsubstituted alkenyl groups having 2 to 20 carbon atoms, such as vinyl, allyl, isopropenyl, 1-butenyl, 2-butenyl, and 3-butenyl; unsubstituted alkynyl groups having 2 to 20 carbon atoms, such as ethynyl, 1-propynyl, 2-propynyl, 1-butynyl, 2-butynyl, and 3-butynyl; cycloalkyl groups having 3 to 20 carbon atoms, such as a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, and a cycloheptyl group; and aryl groups having 6 to 20 carbon atoms, such as a phenyl group, a 1-naphthyl group, a 2-naphthyl group, a 1-anthryl group, a 2-anthryl group, a 9-anthryl group, a tolyl group, and a xylyl group.

[0039] R １ , R ２ Examples of the hydrocarbon group having 1 to 20 carbon atoms and having the above substituent include those in which one or more hydrogen atoms of the unsubstituted hydrocarbon group having 1 to 20 carbon atoms have been substituted with other atoms or substituents. Examples of the "other atoms" as a substituent include halogen atoms such as fluorine, chlorine, and bromine. Examples of the substituent in the substituted alkyl group having 1 to 20 carbon atoms, the substituted alkenyl group having 2 to 20 carbon atoms, and the substituted alkynyl group having 2 to 20 carbon atoms further include a cycloalkyl group having 3 to 20 carbon atoms and an aryl group having 6 to 20 carbon atoms. Examples of the substituent in the substituted cycloalkyl group having 3 to 20 carbon atoms further include an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an alkynyl group having 2 to 20 carbon atoms, and an aryl group having 6 to 20 carbon atoms.

[0040] Among these, R is preferred because it is easy to obtain high purity and large crystals.１ , R ２ As the alkyl group, an unsubstituted hydrocarbon group having 1 to 20 carbon atoms is preferable, and an unsubstituted alkyl group having 1 to 20 carbon atoms is more preferable.

[0041] Specific examples of the host molecule include molecules represented by the following formula (IV-1) or (IV-2).

[0042]

[0043] In formula (IV-1) or (IV-2), R ３ is a hydrogen atom or an alkyl group having 1 to 20 carbon atoms, preferably an alkyl group having 3 to 10 carbon atoms.

[0044] [Guest molecule] The guest molecule constituting the host-guest complex is a molecule accommodated in the internal space of the host molecule. In this specification, a molecule that is ultimately accommodated in the internal space of a host molecule may be referred to as a "guest molecule" even before it is accommodated in the internal space.

[0045] The size of the guest molecule is not particularly limited as long as it can be accommodated in the internal space of the host molecule. The number of atoms constituting the guest molecule (excluding the number of hydrogen atoms) is, for example, 1 to 200, preferably 1 to 150, and more preferably 1 to 100.

[0046] The guest molecule is preferably a molecule having a ring structure. Because the atoms constituting the ring structure tend to have limited free movement, molecules having a ring structure tend to maintain a certain shape. Therefore, when a molecule having a ring structure is used as a guest molecule, a host-guest complex is easily formed in which the guest molecule rotates at high speed within the internal space of the host molecule.

[0047] Examples of molecules having a ring structure include compounds having an adamantane skeleton, compounds having a bicyclo[2.2.2]octane skeleton, compounds having a fused aromatic ring structure, and carborane compounds.

[0048] The compound having an adamantane skeleton is a compound having a structure represented by the following formula (V).

[0049]

[0050] The atoms constituting the skeleton in formula (V) are not limited to carbon atoms, but may be heteroatoms such as nitrogen atoms and sulfur atoms.

[0051] Examples of compounds having an adamantane skeleton include compounds represented by the following formulas (V-1) to (V-28), in which some hydrogen atoms are omitted.

[0052]

[0053]

[0054] The compound having a bicyclo[2.2.2]octane skeleton is a compound having a structure represented by the following formula (VI).

[0055]

[0056] The atoms constituting the skeleton in formula (VI) are not limited to carbon atoms, but may be heteroatoms such as nitrogen atoms and sulfur atoms.

[0057] Examples of compounds having a bicyclo[2.2.2]octane skeleton include compounds represented by the following formulas (VI-1) to (VI-4), in which some hydrogen atoms are omitted.

[0058]

[0059] Examples of compounds having a fused aromatic ring structure include compounds represented by the following formulas (VII-1) to (VII-4), in which hydrogen atoms are omitted.

[0060]

[0061] Examples of the carborane-based compound include compounds represented by the following formulas (VIII-1) to (VIII-4).

[0062]

[0063] [Host-guest complex] The host-guest complex constituting the crystal of the present invention is formed by accommodating the guest molecule in the internal space of the host molecule. The host-guest complex may be one in which one host molecule contains one guest molecule, or two or more guest molecules.

[0064] The guest molecule may be stationary or moving within the internal space of the host molecule. The movement of the guest molecule may be rotational movement within the internal space of the host molecule. This rotational movement may be free rotational movement with a variable rotation axis, or may be rotational movement around a three-fold, four-fold, or six-fold rotational axis of the host molecule.

[0065] In recent years, rattling phenomena, in which atoms vibrate independently of their surroundings, have been reported in compounds with cage-like structures. Materials exhibiting this rattling phenomenon have low thermal conductivity, making them promising thermoelectric materials. The movement of atoms or molecules placed in specific spaces can potentially give rise to interesting physical properties. Host-guest complexes, in which guest molecules rotate within the internal space of host molecules, are particularly promising as raw materials for various devices.

[0066] [Crystal] The crystal of the present invention is formed by the accumulation of the host-guest complex. The crystal of the present invention is a high-purity, large crystal, and is suitable for use as a raw material for various elements such as photoelectric elements and thermoelectric elements. The crystal of the present invention may be a single crystal, a twin crystal, or a polycrystal, but a single crystal or a twin crystal is preferred because of its high purity.

[0067] When a rectangular parallelepiped having three side lengths a, b, and c (where a≧b≧c) that can accommodate the crystal of the present invention is imagined, the rectangular parallelepiped with the smallest volume has a of 1 mm or more, b of 1 mm or more, and c of 0.05 mm or more. By using crystals that satisfy the above requirements as raw materials, various elements can be mass-produced economically. For the above reasons, the rectangular parallelepiped preferably has a of 5 mm or more, b of 5 mm or more, and c of 0.05 mm or more, and more preferably has a of 1 cm or more, b of 1 cm or more, and c of 0.1 mm or more.

[0068] The crystal of the present invention may contain components other than the host-guest complex, such as solvent molecules used in producing the crystal.

[0069] The crystal of the present invention is preferably one in which CH-π interactions and / or π-π interactions exist between adjacent host-guest complexes. As described above, the host molecule used in the present invention is a molecule with excellent plane packing properties having a 3-fold rotation axis, a 4-fold rotation axis, or a 6-fold rotation axis, and therefore the host-guest complex tends to form a two-dimensional sheet-like assembly. If the host-guest complex is one in which CH-π interactions or π-π interactions occur between adjacent molecules, the formation of a two-dimensional sheet-like assembly tends to be promoted. For this reason, crystals with excellent single crystallinity can be easily obtained in a short period of time.

[0070] As described above, the crystal of the present invention includes a crystal containing a two-dimensional sheet-like aggregate formed by a host-guest complex. Among the crystals containing the two-dimensional sheet-like aggregate, those containing multi-layered two-dimensional sheet-like aggregates are preferred. Crystals containing two-dimensional sheet-like aggregates and formed by multi-layered two-dimensional sheet-like aggregates are less likely to lose purity even when grown large, and are therefore suitable for use as raw materials for various elements.

[0071] When the crystal of the present invention is composed of multiple layers of two-dimensional sheet assemblies, solvent molecules may be present as intercalators between the two-dimensional sheet assemblies. In this case, the distance between the two-dimensional sheet assemblies may vary depending on the type of solvent molecule. Thus, by selecting the solvent molecules or adjusting the substituents contained in the host molecule, it may be possible to adjust the distance between the two-dimensional sheet assemblies and the strength of the interaction. Furthermore, by using this method, it may be possible to peel off only one layer of the two-dimensional sheet assemblies on the surface of the crystal.

[0072] 2) Method for Producing Crystals The method for producing crystals of the present invention is a method for producing the crystals, characterized by allowing a solution containing host molecules and guest molecules in an amount of 1 to 10,000 equivalents relative to the host molecules to stand.

[0073] The amount of the guest molecule relative to the host molecule is 1 to 10,000 equivalents, preferably 1 to 1,000 equivalents, and more preferably 5 to 100 equivalents.

[0074] The concentration of the host molecule is, for example, 0.001 to 200 mM, preferably 0.1 to 10 mM, and more preferably 0.3 to 0.4 mM.

[0075] The solvent contained in the solution is not particularly limited as long as it dissolves the host molecule and the guest molecule and precipitates the host-guest complex. Examples of the solvent include aromatic hydrocarbons such as benzene, toluene, xylene, chlorobenzene, 1,2-dichlorobenzene, and nitrobenzene; aliphatic hydrocarbons such as n-pentane, n-hexane, and n-heptane; alicyclic hydrocarbons such as cyclopentane, cyclohexane, and cycloheptane; nitriles such as acetonitrile and benzonitrile; sulfoxides such as dimethyl sulfoxide (DMSO); amides such as N,N-dimethylformamide and N-methylpyrrolidone; ethers such as diethyl ether, tetrahydrofuran, 1,2-dimethoxyethane, and 1,4-dioxane; alcohols such as methanol, ethanol, and isopropyl alcohol; ketones such as acetone, methyl ethyl ketone, and cyclohexanone; cellosolves such as ethyl cellosolve; halogenated hydrocarbons such as dichloromethane, chloroform, carbon tetrachloride, and 1,2-dichloroethane; esters such as methyl acetate, ethyl acetate, ethyl lactate, and ethyl propionate; and water. These solvents may be used alone or in combination of two or more.

[0076] The temperature at which the solution is allowed to stand is, for example, 0 to 100° C., preferably 5 to 25° C. The time for which the solution is allowed to stand is, for example, 1 hour to 50 days, preferably 1 to 7 days.

[0077] The method for producing a crystal of the present invention is thought to include a step in which a host molecule accommodates a guest molecule in its internal space in a solution to form a host-guest complex, and a step in which the formed host-guest complex accumulates.

[0078] Therefore, for example, by mixing a solution of a host molecule A-guest molecule B complex with a solution of a host molecule A-guest molecule C complex, it is possible to obtain crystals containing a host molecule A-guest molecule B complex and a host molecule A-guest molecule C complex. Thus, according to the crystal production method of the present invention, not only can high-purity and large crystals be obtained, but by improving the method, the accommodation state of the guest molecules can also be controlled, allowing crystals having desired properties to be produced efficiently.

[0079] The present invention will be described in more detail below with reference to examples, although the present invention is not limited to the following examples in any way.

[0080] [Single Crystal X-Ray Structural Analysis] Single crystal X-ray structural analysis was carried out using the large synchrotron radiation facility Spring-8 BL26B1, the High Energy Accelerator Research Organization (KEK) Photon Factory (PF) BL17A, or XtaLAB P200 (Rigaku Corporation).

[0081] [Analysis of Interactions Between Host Molecules] Hirshfeld surface analysis and AIM (atoms-in-molecules) analysis were carried out to examine interactions between host molecules.

[0082] Synthesis Example 1 Synthesis of Host Molecule A host molecule having the following structure was synthesized in the same manner as in the method described in Non-Patent Document 1.

[0083]

[0084] In the formula, "n-Hex" represents an n-hexyl group. Hereinafter, this host molecule will be referred to as "(P)-[3]C ｄｂ C-C ６ ". The host-guest complex containing this host molecule is referred to as "(P)-[3]C ｄｂ C-C ６ ⊃X" (X is the number of the guest molecule).

[0085] Example 1 (P)-[3]C ｄｂ C-C ６ Adamantane (1) (12 mg, 8.0 μmol) and adamantane (1) (5.5 mg, 40 μmol) were dissolved in a mixed solvent of dichloromethane (12 mL) and acetonitrile (12 mL). The resulting solution was transferred to a Petri dish with a diameter of 64 mm and a depth of 20 mm and a glass lid. This was placed in an incubator and left to stand at 25°C for 5 days. As a result, centimeter-scale hexagonal plate-like crystals were obtained. Photographs of the obtained crystals are shown in Figures 1 to 3. Furthermore, by performing a similar experiment on a smaller scale and in a simplified manner, microcrystals on the order of just under a millimeter were obtained. These microcrystals were used as the measurement sample for crystal structure analysis.

[0086] [Single Crystal X-ray Structure Analysis] The microcrystals obtained in Example 1 were used as measurement samples to carry out single crystal X-ray structure analysis. The results are shown in Figures 4 and 5. Figure 4 is a diagram showing the intermolecular state. The host-guest complex [(P)-[3]C ｄｂ C-C ６ ⊃1] are two-dimensionally assembled to form two-dimensional sheet-like aggregates. Furthermore, the two-dimensional sheet-like aggregates are stacked, causing the crystal to grow three-dimensionally. In addition, solvent molecules, such as dichloromethane, exist between the two-dimensional sheet-like aggregates as an intercalator. Figure 5 shows the structure of the host-guest complex [(P)-[3]C ｄｂ C-C ６ ⊃1]. From this figure, it is clear that the host molecule [(P)-[3]C ｄｂ C-C ６ It can be seen that adamantane molecules are incorporated into the internal space of the .

[0087] [Analysis of host-molecule interactions] FIG. 6 shows the d ｅ Hirshfeld map shown. ｅ In the "Hirshfeld map," the distance between the surface of a molecule and its nearby atoms is visualized. The host-guest complex [(P)-[3]C ｄｂ C-C ６ ⊃1] one of ｄｂNear the C panel is the adjacent host-guest complex [(P)-[3]C ｄｂ C-C ６ ⊃1] two ｄｂ There are a total of six CH parts included in the C panel. Figure 7 shows the results of the AIM analysis. From the results of the AIM analysis, ｄｂ It can be seen that there is a CH-π interaction between the C panel and the CH portion.

[0088] [Rotational motion of guest molecules] As described in Non-Patent Document 2, the solid-state host-guest complex [(P)-[3]C ｄｂ C-C ６ The adamantane molecules in the host molecule rotate within the internal space of the host molecule, with the rotational frequency in the terahertz region. The crystals obtained in Example 1 are significantly larger than previous microcrystals, and are expected to be used in a variety of functional materials.

[0089] Reference Example 1: In the small-scale experiment of Example 1, [(P)-[3]C ｄｂ C-C ６ ⊃1] was obtained. Single crystal X-ray structural analysis was performed using the obtained crystal, and it was found that two-dimensional sheet assemblies were stacked, similar to the crystal in Example 1. Note that this crystal contained benzene instead of dichloromethane as an intercalator. When dichloromethane was used as an intercalator (Example 1), the thickness of one layer of the two-dimensional sheet assemblies was 1.51 nm, while when benzene was used as an intercalator (Reference Example 1), the thickness of one layer of the two-dimensional sheet assemblies was 1.54 nm.

[0090] (Delamination Experiment) The crystal obtained in Reference Example 1 was fixed to adhesive tape on a glass plate. Next, another adhesive tape was attached to this crystal, and then this adhesive tape was peeled off. When the crystal was observed using an atomic force microscope (Nanowizard 3, JPK Instruments), it was found that there were steps on the crystal surface, with a region that was approximately 2 nm lower than the higher point. 2 nm corresponds to the thickness of one layer of the two-dimensional sheet-like assembly. Therefore, it is believed that this method can peel off one layer of the two-dimensional sheet-like assembly over a wide area.

[0091] Reference Examples 2 to 33: In the small-scale experiment of Example 1, the host-guest complexes [(P)-[3]C ｄｂ C-C ６ ⊃X: X = 2 to 32] was obtained. Single crystal X-ray structure analysis was performed using these microcrystals as samples, and it was found that they were composed of stacked two-dimensional sheet-like assemblies, similar to the crystals in Example 1.

[0092]

[0093]

[0094] Reference Synthesis Examples 1 to 5 Host molecules having the following structures were synthesized in the same manner as in Synthesis Example 1 above.

[0095]

[0096] In the formula, R represents an n-propyl group, an n-butyl group, an n-pentyl group, an n-heptyl group, or an n-octyl group.

[0097] [Reference Examples 34 to 38] In the small-scale experiments of Example 1, (P)-[3]C ｄｂ C-C ６ Microcrystals of the host-guest complex were obtained in the same manner as in Example 1, except that the host molecules obtained in Reference Synthesis Examples 1 to 5 were used instead of the host molecules obtained in Reference Synthesis Examples 1 to 5. Single crystal X-ray structural analysis was performed using these microcrystals as samples, and it was found that they were composed of stacked two-dimensional sheet-like assemblies, similar to the crystals of Example 1.

Claims

1. A crystal formed by aggregation of host-guest complexes, wherein the host-guest complex is composed of a host molecule having an internal space and an opening, and a guest molecule accommodated in the internal space of the host molecule, the host molecule is a molecule having a three-fold rotation axis, a four-fold rotation axis or a six-fold rotation axis, and when a rectangular parallelepiped with side lengths a, b, and c (where a ≥ b ≥ c) that can accommodate the crystal is imagined, a of the rectangular parallelepiped with the minimum volume is 1 mm or more, b is 1 mm or more, and c is 0.05 mm or more.

2. The crystal according to claim 1, wherein when the largest circle that fits into the opening of the host molecule is imagined, the diameter of the circle is 0.7 to 1.7 nm.

3. The crystal according to claim 1, wherein the host molecule is a chiral molecule, and the host molecules contained in the crystal are one of the enantiomers.

4. The crystal according to claim 1, wherein the host molecule is a molecule composed of non-metal elements.

5. The crystal according to claim 1, wherein the host molecule is a cylindrical molecule having openings at both ends.

6. The crystal according to claim 5, wherein the host molecule is a molecule represented by the following formula (I). [In formula (I), A represents a group having a condensed ring structure. n is 3, 4, or 6.] 7. The crystal according to claim 6, wherein A is a group having a partial structure represented by the following formula (II). [In formula (II), * represents a bond.] 8. The crystal according to claim 7, wherein A is a group represented by the following formula (III). [In formula (III), R １ , R ２ each independently represents a hydrogen atom, a halogen atom, or an unsubstituted or substituted hydrocarbon group having 1 to 20 carbon atoms. * represents a bond.] 9. The crystal according to claim 1, wherein the guest molecule is a molecule having 1 to 200 atoms (excluding the number of hydrogen atoms) that make up the guest molecule.

10. The crystal according to claim 1, wherein the guest molecule is a molecule having a ring structure.

11. The crystal according to claim 1, wherein the guest molecule is rotating within the internal space of the host molecule.

12. The crystal according to claim 1, wherein there is a CH-π interaction and / or a π-π interaction between adjacent host-guest complexes.

13. The crystal according to claim 1, wherein the crystal includes a two-dimensional sheet-like aggregate formed by the host-guest complex.

14. The crystal according to claim 13, wherein the crystal is formed by multi-layering of the two-dimensional sheet-like aggregate.

15. A method for producing the crystal according to claim 1, characterized by allowing a solution containing a host molecule and 1 to 10,000 equivalents of a guest molecule with respect to the host molecule to stand still.

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