Crystal, and method for manufacturing the same

Abstract

To provide a highly pure and large crystal of a host-guest complex, and a method for manufacturing the crystal.SOLUTION: A crystal according to the present invention is formed as a result of accumulation of a host-guest complex constituted of: a host molecule having an opening part and an internal space; and a guest molecule housed in the internal space of the host molecule. Therein: 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 which can house the crystal and in which lengths of 3 sides are a, b, c (where a≥b≥c) is assumed, 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 a minimum capacity. A method for producing the crystal is also provided.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Some host-guest complexes have attracted attention as raw materials for various devices such as photoelectric devices and thermoelectric devices. For this reason, in recent years, measurements of the physical properties of host-guest complexes in the solid state 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). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-92229 [Non-patent literature]

[0006] [Non-Patent Document 1] Angew.Chem.Int.Ed.58,7385-7389(2019) [Non-patent document 2] Nat.Commun.12,5062(2021) Summary of the Invention [Problem to be solved by the invention]

[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. That is, when a single crystal is directly molded to manufacture an element, a larger crystal is required. Also, when a single crystal is crushed and then molded to manufacture 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. [Means for solving the problem]

[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 discovered that molecules with specific rotational symmetry have excellent planar packing properties, and therefore 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, leading to the completion of the present invention.

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

[14] and a method for producing the crystal

[15] are provided.

[0011] [1] A crystal formed by the accumulation of a host-guest complex, 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, wherein 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 having three sides with 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 the diameter of the largest imaginary circle that fits into the opening of the host molecule 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 one of [1] to [3], wherein the host molecule is a molecule composed of a non-metal element. [5] The crystal according to any one of [1] to [4], wherein the host molecule is a cylindrical 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] [ka]

[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] [ka]

[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] [ka]

[0017] [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 any one of [1] to [8], wherein the guest molecule is a molecule having 1 to 200 atoms (excluding the number of hydrogen atoms) constituting the guest molecule.

[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 rotates within the internal space of the host molecule.

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

[11] , wherein a CH-π interaction and / or a 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 complex.

[14] The crystal according to

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

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

[14] , characterized by allowing a solution containing a host molecule and a guest molecule in an amount of 1 to 10,000 equivalents relative to the host molecule to stand. [Effects of the Invention]

[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. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a photograph of the crystals obtained in Example 1. [Figure 2] FIG. 1 is a diagram showing the molecular structure of the host-guest complex that constitutes the crystal obtained in Example 1. [Figure 3] 1 is a de Hirshfeld map of the host-guest complex that constitutes the crystal obtained in Example 1. [Figure 4] FIG. 1 shows the results of AIM analysis of the host-guest complex that constitutes the crystal obtained in Example 1. DETAILED DESCRIPTION OF THE INVENTION

[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 host-guest complexes. 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 fits into the opening of the host molecule is imagined, the diameter of the circle is preferably 0.7 to 1.7 nm, more preferably 0.9 to 1.5 nm. The diameter of the largest circle that fits 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 molecules having these rotation axes as host molecules, it becomes easier to obtain crystals containing two-dimensional sheet-like assemblies formed by host-guest complexes. 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 been attracting attention as functional materials. In research on MOFs, a variety of molecules have been created by utilizing the bonds between transition metal ions and ligands. However, some MOFs require rare metals as essential components, and using such MOFs as raw materials for various devices poses challenges in terms of economic viability and mass production. In this respect, host molecules composed of nonmetallic elements are more suitable as raw materials for various devices.

[0029] The host molecule is preferably a cylindrical molecule with openings at both ends. When the host molecule has such a shape, the host-guest complex is rapidly formed during the crystal production process, allowing for the efficient production of high-purity, large crystals. In addition, 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 includes a molecule represented by the following formula (I).

[0031] [ka]

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

[0033] [ka]

[0034] In formula (II), * represents a bond. When a cylindrical 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 the group having the partial structure represented by formula (II) include a group represented by the following formula (III).

[0035] [ka]

[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 2 Examples 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 group having 1 to 20 carbon atoms include: unsubstituted alkyl groups having 1 to 20 carbon atoms, such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, an isobutyl group, a tert-butyl group, an n-pentyl group, an n-hexyl group, an n-heptyl group, an n-octyl group, an n-nonyl group, or an n-decyl group; unsubstituted alkenyl groups having 2 to 20 carbon atoms, such as a vinyl group, an allyl group, an isopropenyl group, a 1-butenyl group, a 2-butenyl group, or a 3-butenyl group; unsubstituted alkynyl groups having 2 to 20 carbon atoms, such as an ethynyl group, a 1-propynyl group, a 2-propynyl group, a 1-butynyl group, a 2-butynyl group, or a 3-butynyl group; 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; 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; Examples include:

[0039] R 1 , R 2Examples 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 atom" as a substituent include halogen atoms such as a fluorine atom, a chlorine atom, and a bromine atom. Further 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 include a cycloalkyl group having 3 to 20 carbon atoms and an aryl group having 6 to 20 carbon atoms. Further examples of the substituent in the cycloalkyl group having 3 to 20 carbon atoms 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 the most popular 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] [ka]

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

[0044] [Guest molecule] The guest molecule that constitutes the host-guest complex is a molecule accommodated in the internal space of the host molecule. In this specification, the molecule that is ultimately accommodated in the internal space of the 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] [ka]

[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] [ka]

[0053] [ka]

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

[0055] [ka]

[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 formulas (VI-1) to (VI-4), some hydrogen atoms are omitted.

[0058] [ka]

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

[0060] [ka]

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

[0062] [ka]

[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 may be one in which one host molecule contains two or more guest molecules.

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

[0065] Recently, 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. In this way, the movement of atoms or molecules placed in a specific space can give rise to interesting physical properties, and host-guest complexes in which the guest molecule rotates within the internal space of the host molecule 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 imagining a rectangular parallelepiped with three sides of lengths a, b, and c (where a≧b≧c) that can accommodate the crystal of the present invention, 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 reasons mentioned above, 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 a C—H-π interaction and / or a π-π interaction exists between adjacent host-guest complexes. As described above, the host molecule used in the present invention is a molecule with excellent planar packing properties and a three-fold, four-fold, or six-fold rotation axis, and therefore the host-guest complex tends to form a two-dimensional sheet-like assembly. If the host-guest complex has C—H-π or π-π interactions between adjacent molecules, the formation of two-dimensional sheet-like aggregates tends to be promoted, making it easier to obtain crystals with excellent single crystallinity in a short time.

[0070] As described above, the crystals of the present invention include those containing two-dimensional sheet-like assemblies formed by host-guest complexes. In the crystal containing the two-dimensional sheet-like aggregate, the two-dimensional sheet-like aggregate is preferably multi-layered. Crystals that contain two-dimensional sheet-like aggregates and are formed by multi-layering them are suitable for use as raw materials for various elements because their purity is unlikely to decrease even when they grow large.

[0071] When the crystal of the present invention is composed of multiple layers of two-dimensional sheet assemblies, solvent molecules may exist as intercalators between the two-dimensional sheet assemblies. In this case, the distance between the two-dimensional sheet assemblies may change depending on the type of solvent molecules. In this way, by selecting the solvent molecules or adjusting the substituents in the host molecule, it is sometimes possible to adjust the distance between the two-dimensional sheet-like assemblies and the strength of their interactions. By using this method, it is sometimes possible to peel off only one layer of the two-dimensional sheet-like assemblies on the surface of the crystal.

[0072] 2) Crystal manufacturing method The method for producing a crystal of the present invention is a method for producing the crystal, characterized in that a solution containing a host molecule and 1 to 10,000 equivalents of a guest molecule relative to the host molecule is allowed 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 relative to the host molecule.

[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 solvents 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 can be used alone or in combination.

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

[0077] The method for producing crystals 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 the host molecule A-guest molecule B complex and the host molecule A-guest molecule C complex. Thus, the crystal manufacturing method of the present invention not only allows for the production of high-purity, large crystals, but also makes it possible to control the accommodation state of guest molecules by improving the method, thereby enabling the efficient production of crystals with the desired properties. [Example]

[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 Structure Analysis] Single-crystal X-ray structure analysis was performed 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] [Host-molecular interaction analysis] Hirshfeld surface analysis and AIM (atoms-in-molecules) analysis were performed to investigate the interactions between the host molecules.

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

[0083] [ka]

[0084] In the formula, "n-Hex" represents an n-hexyl group. Hereinafter, this host molecule will be referred to as "(P)-[3]C db The host-guest complex containing this host molecule is referred to as "(P)-[3]C db It is expressed as "C-C6⊃X" (X is the number of the guest molecule).

[0085] Example 1 (P)-[3]C dbC-C6 (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 allowed to stand at 25°C for 5 days. As a result, centimeter-scale hexagonal plate-like crystals were obtained. Figure 1 shows a photograph of the resulting crystals. Furthermore, by performing a similar experiment on a smaller scale and in a simplified manner, we obtained microcrystals of a size less than a millimeter in size, which were used as measurement samples for crystal structure analysis.

[0086] [Single Crystal X-ray Structure Analysis] The microcrystals obtained in Example 1 were used as measurement samples and subjected to single crystal X-ray structural analysis, the results of which are shown in FIG. Figure 2(a) shows the intermolecular state of the host-guest complex [(P)-[3]C db C-C6⊃1] are assembled two-dimensionally to form two-dimensional sheet-like aggregates. Furthermore, the two-dimensional sheet-like aggregates are stacked, resulting in three-dimensional growth of the crystal. In addition, solvent molecules, such as dichloromethane, exist between the two-dimensional sheet-like aggregates as intercalators. Figure 2(b) shows the host-guest complex [(P)-[3]C db This figure shows the structure of the host molecule [(P)-[3]C db It can be seen that adamantane molecules are incorporated into the internal space of the hydroxyl group [C-C6].

[0087] [Host-molecular interaction analysis] Figure 3 shows the d e The Hirshfeld map is shown below. e In a "Hirshfeld map," the distance between the surface of a molecule and its nearby atoms is visualized. The host-guest complex ((P)-[3]C) is located at the center of Figure 3. db C-C6⊃1) dbNear panel C, the adjacent host-guest complex [(P)-[3]C db C-C6⊃1] db There are a total of six CH sections included in the C panel. The results of the AIM analysis are shown in Figure 4. 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 part.

[0088] [Rotational motion of guest molecules] As described in Non-Patent Document 2, the solid-state host-guest complex [(P)-[3]C db The adamantane molecules in the C-C6⊃1 complex rotate within the internal space of the host molecule, with rotational frequencies in the terahertz range. The crystals obtained in Example 1 are significantly larger than the microcrystals obtained up to now, and are expected to be used as various functional materials.

[0089] [Reference example 1] In the small-scale experiment of Example 1, [(P)-[3]C db C-C6⊃1] crystals were obtained. Single-crystal X-ray structural analysis of the obtained crystals revealed that they were composed of stacked two-dimensional sheet-like assemblies, similar to the crystals of Example 1. Note that these crystals 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-like assembly was 1.51 nm, whereas when benzene was used as an intercalator (Reference Example 1), the thickness of one layer of the two-dimensional sheet-like assembly was 1.54 nm.

[0090] (Delamination experiment) The crystal obtained in Reference Example 1 was fixed to an adhesive tape on a glass plate, and then another adhesive tape was attached to the crystal, and then the 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 areas approximately 2 nm lower than the higher points. 2 nm corresponds to the thickness of one layer of the two-dimensional sheet-like assembly, and therefore, this method is thought to be capable of peeling 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 complex [(P)-[3]C db C-C⊃X:X=2 to 32)] were 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] [ka]

[0093] [ka]

[0094] [Reference synthesis examples 1 to 5] A host molecule having the following structure was synthesized in the same manner as in Synthesis Example 1 above.

[0095] [ka]

[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 34-38] In the small-scale experiment of Example 1, (P)-[3]C dbMicrocrystals 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 C-C6. 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 in Example 1.

Claims

1. 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, When a rectangular parallelepiped having three sides with 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.

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

3. The crystal according to claim 1, 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 claim 1 , wherein the host molecule is a molecule composed of non-metallic 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): 【Chemical 1】 [In formula (I), A represents a group having a fused ring structure, and 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): 【Chemistry 2】 [In formula (II), * represents a bond.]

8. The crystal according to claim 7, wherein A is a group represented by the following formula (III): 【Chemistry 3】 [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. 2. The crystal according to claim 1, wherein the guest molecule is a molecule having 1 to 200 atoms (excluding the number of hydrogen atoms) constituting the guest molecule.

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

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

12. The crystal according to claim 1, wherein CH-π interactions and / or π-π interactions exist between adjacent host-guest complexes.

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

14. The crystal according to claim 13 , wherein the crystal is formed by multilayering the two-dimensional sheet-like assemblies.

15. 2. A method for producing a crystal according to claim 1, 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.

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