Chirality Generation in Supramolecular Clusters: Analogues of

Article pubs.acs.org/crystal

Chirality Generation in Supramolecular Clusters: Analogues of Octacoordinated Polyhedrons Published as part of the Crystal Growth & Design virtual special issue of selected papers presented at the 11th International Workshop on the Crystal Growth of Organic Materials (CGOM11 Nara, Japan), a joint meeting with Asian Crystallization Technology Symposium (ACTS 2014) Toshiyuki Sasaki,* Yoko Ida, Tetsuharu Yuge, Atsushi Yamamoto, Ichiro Hisaki, Norimitsu Tohnai, and Mikiji Miyata*,‡ Department of Material and Life Science, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan S Supporting Information *

ABSTRACT: Metal-free supramolecular clusters, comprising organic salts of triphenylacetic acid and primary amines, were characterized for the first time as the analogues of octacoordinated polyhedrons with a novel supramolecular chirality in the crystalline state. A ternary system yields triangular dodecahedrons with chiral belts composed of four triphenylmethyl (trityl) groups involving right- or left-handed twist combinations (Δ:Λ = 4:0 or 0:4). The 12 benzene rings are divided into three layers along a 2-fold axis of symmetry, affording a structure that is similar to a censer (a traditional vessel for fragrance) comprising three parts: a head, body, and foot. A binary system with t-butylammonium or t-amylammonium provides different chiral triangular dodecahedrons, while the system with isobutylammonium provides a trans-bicapped octahedron with a 3-fold rotational axis of symmetry to yield a chiral belt of four trityl groups (Δ:Λ = 3:1 or 1:3).

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INTRODUCTION egular polyhedrons may change to polyhedrons with distorted and complex structures. For example, a regular cube with eight edges (Figure 1a(rc)) is distorted around a 2-, 3-, and 4-fold rotational axis to yield a triangular dodecahedron with a 2-fold rotational axis (Figure 1a(i)), a trans-bicapped octahedron with a 3-fold axis (Figure 1a(ii)), and a square antiprism with a 4-fold rotational axis (Figure 1a(iii)), respectively.1 When the polyhedron consists of multicomponents, the eight edges may be occupied in various manners, as shown in two or three components with alternative positions (Figure 1b(i−iii) and c(i−iii)). Various inorganic compounds are known to provide the multicomponent polyhedrons.2 Metal ions coordinate with multiple ligands and yield diverse coordination compounds,3 which are classified into multiple-coordination polyhedrons on the basis of arrangements of the ligands according to the IUPAC nomenclature.1 However, in metal-free organic substances, only regular cubic hexahedrons are well-known, while the others are considered as exceptional cases.4 For example, organic salts such as ammonium halides,5 carboxylates,6 sulfonates,7 phosphates,8 and water molecules9 afford supramolecular clusters by forming cubic hydrogen-bonding (HB) networks. To the best of our knowledge, supramolecular assemblies, particularly the analogues of octacoordinated polyhedrons derived from regular cubes, have not been reported even though these polyhedrons may exhibit interesting structure-dependent functions.

In the past decade, our study has been devoted to cubic (4 + 4) clusters with bulky triphenylmethyl (trityl) groups.6−8 Recently, this research has led to the finding that these clusters are the analogues of octacoordinated polyhedrons (Figure 1a(i−iii)) rather than regular cubes (Figure 1a(rc)). Such polyhedral supramolecular clusters have the ability to generate supramolecular chirality although the constituent molecules are achiral (Figure 1b−d). Until now, we have prepared many supramolecular (4 + 4) clusters of organic salts containing trityl groups through closed HB networks. The trityl groups have conformational chirality, Δ (right-handed) and Λ (left-handed),10a useful for chiral separation as reported by Okamoto’s group (Figure 2a).10b The HB networks belong to a regular cubic-type networks with various symmetries from a topological viewpoint (Figure 2b). These clusters appear as distorted cubes, depending on the primary amines used. In fact, four trityl and alkyl groups align in various ways, forming distorted clusters; i.e., alkyl groups may force trityl groups to form different conformations. Therefore, different combinations of the conformations may form diverse analogues of octacoordinated polyhedrons. This idea inspired us to characterize the clusters from various viewpoints in detail.

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© 2014 American Chemical Society

Received: September 8, 2014 Revised: December 12, 2014 Published: December 30, 2014 658

DOI: 10.1021/cg5013445 Cryst. Growth Des. 2015, 15, 658−665

Article

Crystal Growth & Design Table 1. Characterization of the Supramolecular Clusters of Organic Salts Composed of TPAA and Primary Amines entries (Refcode or CCDC nos.)

topology of HB

handedness of trityl (C1:C2:C3:C4,Λ:Δ)

octahedral polyhedron

TPAA-ac

C2/C2′

triangular dodecahedron

Λ:Λ:Λ:Λ, 4:0

(973399) TPAA-ad

D2d


Δ:Δ:Δ:Δ, 0:4 Λ:Λ:Λ:Λ, 4:0

(973398) TPAA-bc

D2d


Δ:Δ:Δ:Δ, 0:4 Λ:Λ:Λ:Λ, 4:0

(973397) TPAA-bd

D2d


Δ:Δ:Δ:Δ, 0:4 Λ:Λ:Λ:Λ, 4:0

(973396) TPAA-a

D2d

square antiprism

Δ:Δ:Δ:Δ, 0:4 Λ:Δ:Λ:Δ, 2:2

(MIBTOHb) TPAA-b1

CS

trans-bicapped octahedron

(or Δ:Λ:Δ:Λ) Λ:Λ:Λ:Δ, 3:1

(GIVFEXc) TPAA-b2

C1(b)/C1(b)′

intermediate of triangular dodecahedron and trans-bicapped octahedron

Λ:Δ:Δ:Δ, 1:3 Λ:Δ:ΔΛ:Δ, 1:2(:1)

2-fold rotational axis; chiral 2-fold rotational axis; chiral 2-fold rotational axis; chiral 2-fold rotational axis; chiral 2-fold rotational axis; achiral 3-fold rotational axis; chiral no rotational axis; chiral

Δ:Λ:ΔΛ:Λ, 2:1(:1)

(MIBVAVb) TPAA-c

S4


Λ:Λ:Δ:Δ, 2:2

2-fold rotational axis; chiral

(GIVFIBc) TPAA-d

S4


Δ:Δ:Λ:Λ, 2:2

2-fold rotational axis; chiral

(973395) a

symmetry

number of benzene rings around ammoniums (layer)a ammonium c, two (upper) ammonium a, four (lower) ammonium d, two (upper) ammonium a, four (lower) ammonium c, two (upper) ammonium b, four (lower) ammonium d, two (upper) ammonium b, four (lower) 1. Two (upper), one (middle) 2. One (middle), two (lower) 1. One (upper), two (middle) 2. Three (lower) 1. Two (upper), one (middle) 2. One (upper), two (middle), two (lower) 1. Two (upper), one (middle) 2. One (middle), two (lower) 1. Two (upper), one (middle) 2. One (middle), two (lower)

Figures 4−8f,g. bSee ref 6. cSee ref 11.

Figure 2. (a) Chiral conformations of trityl groups, right (Δ) and left (Λ), and their combinations in each cluster. (b) Topologically cubic hydrogen-bonding networks with six types of symmetries: D2d, S4, CS, C2, C1(a), and C1(b).

Figure 1. Schematic representations of the supramolecular assemblies as the analogues of the octacoordinated polyhedrons; regular cube (rc), triangular dodecahedron a(i), trans-bicapped octahedron a(ii), square antiprism a(iii), distorted around a 2-, 3-, and 4-fold rotational axis; plausible eight positions for two or three components of organic salts b(i−iii) or c(i−iii); and plausible one-handed arrangements of the acid components d(i−iii).

left-handed conformation (Δ:Λ = 4:0 or 0:4) of trityl groups (Figure 1d(i)).

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RESULTS AND DISCUSSION We used organic salts composed of triphenylacetic acid (TPAA) and four different primary amines: n-butylamine (a),

Finally, we concluded that a three-component system forms chiral triangular dodecahedrons having either right-handed or 659


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Crystal Growth & Design

isobutylamine (b), t-butylamine (c), and t-amylamine (d) (Figure 3a). TPAA and the amines were mixed in methanol with a 1:1 molar ratio of TPAA/amine for binary systems or a 2:1:1 molar ratio of TPAA/amine-1/amine-2 for ternary systems. Evaporation of the solutions yielded their powdered salts, which were recrystallized from a toluene/hexane mixture. The salts of TPAA-d and the ternary systems afforded good crystals in the case of four combinations of the amines (ac, ad, bc, and bd), while the other combinations, ab, cd, only afforded the crystal mixtures of TPAA-a and -d and TPAA-c and -d, respectively. The obtained crystals were subjected to infrared spectroscopic analysis (Supporting Information, Figures S1− S8) and single-crystal X-ray diffraction analysis. The crystal structures of the binary system belong to the P4̅21c (TPAA-a),6 P21/n and R3̅c (TPAA-b),6,11 C2/c (TPAA-c),11 and C2/c (TPAA-d), while those of the ternary systems belong to the C2/c space group with almost the same crystal structures (Supporting Tables S1, and S2 and Figure S9).12 Notably, the racemic compounds contain not only the achiral clusters but also both the enantiomeric clusters. The clusters were evaluated from the following five viewpoints (I)−(V). (I) Topology of the HB cores (Figure 2b).

Figure 3. (a) Organic components of triphenylacetic acid (TPAA) and primary amines: n-butylamine (a), isobutylamine (b), t-butylamine (c) and t-amylamine (d), used in this study. (b) Supramolecular binary (4 + 4) and ternary (4 + 2 + 2) clusters.

Figure 4. A three-component cluster of TPAA-ad (triangular dodecahedron) with a 2-fold rotational axis; one cluster with a space-filling representation (a), topologically cubic hydrogen-bonding network (b), eight positions of the components and conformations of four trityl groups (c), three-layered arrangements of 12 benzene rings (d), schematic representation of a censer with two tops and four legs (e), and holes accommodating the ammoniums d in the top (f) and a in the foot (g). (h) Intercluster contact around an inversion center. (i) Cluster stacking in a 2-fold rotational and helical manner along the b axis. (j) A packing diagram with 2-fold rotational and helical axes. The Δ and Λ trityl groups and primary ammoniums a and d are colored in blue, pink, orange, and green, respectively. 660


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Figure 5. A two-component cluster of TPAA-d (triangular dodecahedron) with a 2-fold rotational axis; one cluster with a space-filling representation (a), topologically cubic hydrogen-bonding network (b), eight positions of the components and conformations of four trityl groups (c), two-layered arrangements of 12 benzene rings (d), schematic representation of a hamburger (e), and holes accommodating the ammoniums d in the upper side (f) and in the lower side (g). (h) Intercluster contact around an inversion center. (i) Head-to-tail stacking of the clusters along a 2-fold axis. (j) A packing diagram with 2-fold rotational and 2-fold helical axes. The Δ and Λ trityl groups and primary ammonium d are colored in blue, pink, and orange, respectively.

one of the enantiomers using a space-filling representation, as viewed along the 2-fold axis. Four trityl groups intermesh along the axis to form a zigzag belt. The core has a D2d HB network (Figure 4b). Considering the axis and positions of eight edges (Figure 4c), the cluster belongs to a triangular dodecahedron with a 2-fold rotational axis. The trityl groups have combinations of twist conformations with one-handedness (Δ:Λ = 4:0). Therefore, the cluster has a topographically (conformationally) chiral shell and a topologically achiral HB core; thus, it is chiral as a whole. The cluster in Figure 4a is right-handed, while the other enantiomeric cluster is left-handed (Supporting Information, Figure S10). The 12 benzene rings of four trityl groups are divided into three layers: an upper layer with two rings, a middle layer with six rings, and a lower layer with four rings (Figure 4d). The middle wavy layer surrounds the sides of the cubic-HB networks. Such an architecture is similar to a traditional vessel for fragrance, called a censer (Figure 4e). The 12 benzene rings construct a two-membered head, a six-membered body, and a four-membered foot. Two molecules of d are surrounded by two benzene rings of the upper layer (Table 1, Figure 4f), while those of ammonium a are surrounded by four rings of the lower layer (Table 1, Figure 4g). The enantiomeric clusters assembled using the Δ and Λ trityl groups generate an inversion center (Figure 4h). The onehanded clusters stack along the b axis with a slight shift along

As previously reported, there are nine different cubic HB networks, including three achiral, D2d, S4, and CS, and three enantiomeric pair networks, C2/C2′, C1(a)/C1(a)′, C1(b)/C1(b)′.6 (II) Distortions of the clusters. The molecular arrangements in the clusters were different than in the cube, and they were ascertained from the viewpoints of rotational axes of symmetry and the relative positions of the eight components, thus enabling determination of the corresponding subgroup of the octacoordinated polyhedrons. (III) Chirality of the shells. The trityl groups, composing the shells, have chirality due to their conformation.10 Four trityl groups have various combinations of Δ and Λ (Figure 2a). (IV) Layered structures of the shells. The benzene rings of the four trityl groups arranged themselves in three different layers because of the different steric arrangements around the rotational axes. (V) Holes of the shells. We observed alignment of the benzene rings around the ammoniums, thus enabling accommodation of the different alkyl groups flexibly. These results are summarized in Table 1. Three-component clusters. The three-component clusters consist of cores with HB networks and the shells with trityl and alkyl groups. The cores have the topologically cubic HB networks. TPAA-ad, TPAA-bc, and TPAA-bd exhibit D2d symmetry, while TPAA-ac exhibits C2/C2′ symmetry.12 These networks indicate an existence of 2-fold rotational axes, for example, the enantiomeric cluster of TPAA-ad. Figure 4a shows 661


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Figure 6. A two-component cluster of TPAA-a (square antiprism): one cluster with a space-filling representation (a), topologically cubic hydrogenbonding network (b), eight positions of the components and conformations of four trityl groups (c), layered arrangements of 12 benzene rings (d), schematic representation of a boat (e), and holes accommodating the ammoniums a in the top (f) and foot (g). (h) Intercluster contact around a 4-fold rotation-inversion axis. (i) Head-to-tail stacking of the clusters along a 4-fold rotation−inversion axis. (j) A packing diagram with 2-fold rotational, 2-fold helical, and 4-fold rotation−inversion axes. The Δ and Λ trityl groups and the primary ammonium a are colored in blue, pink, and orange, respectively.

located on the middle parts, the cluster looks like a hamburger (Figure 5e). The upper or lower ammoniums d are surrounded by three benzene rings: two of the upper or lower layer and one of the middle layers. (Table 1, Figure 5f,g). The enantiomeric clusters assemble around inversion centers with no prominent interactions (Figure 5h). The one-handed clusters stack in a head-to-tail manner along the b axis with 2-fold rotational axes (Figure 5i), forming a “hamburgers-on-astick”. The hamburgers are on a single axis without any shifts, unlike the stacking of the crystals of the ternary salts. In the ternary system, the ammonium components are arranged on the upper and lower sites of the cluster, resulting in the assembly with a slight shift along the a axis due to the steric factors. This result shows that the stacking manners of the clusters vary depending on the positions of the ammoniums in the clusters. The columns of the “hamburgers-on-a-stick” are bundled along the a and c axes with 2-fold helices and inversion centers, respectively, to afford a racemic compound (Figure 5j). The cluster of TPAA-a has the D2d-type HB network, indicating the presence of a 2-fold rotational axis.6 The eight edges indicate that the cluster is a square antiprism, which is very similar to a cube (Table 1 and Figure 6). TPAA-a is similar to TPAA-c or TPAA-d as a whole, but the distance between the

the a axis, thus forming 2-fold helical columns (Figure 4i). The helical columns are bundled along the a and e axes with 2-fold rotational axes and inversion centers, respectively, thus affording a racemic compound (Figure 4j). In the same manner, the other salts of the ternary systems construct and assemble the triangular dodecahedron clusters to form the racemic compounds. Two-component clusters. In contrast, the two-component clusters (TPAA-c, and -d) have the S4-type HB networks and 2-fold rotational axes (Table 1 and Figure 5 for TPAA-d).11,12 Figure 5a shows one of the enantiomers with a space-filling representation, as viewed along the 2-fold axis. The other enantiomeric cluster is shown in Supporting Information, Figure S11. In contrast to TPAA-ad, four ammonium groups intermesh along the axis to form a narrow zigzag belt. The HB network (Figure 5b) shows that the 2-fold rotational axes and positions of eight edges (Figure 5c) belong to the triangular dodecahedrons. As viewed along the axis, the two Δ of four trityl groups occupy an upper side, while the other two Λ occupy a lower side. The distance between the former groups is different from that between the latter groups, indicating that the cluster is chiral as a whole. The 12 benzene rings are divided into three layers with four rings (Figure 5d). Because the ammonium molecules are 662


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Figure 7. A two-component cluster of TPAA-b1 (trans-bicapped octahedron) with a 3-fold rotational axis; one cluster with a space-filling representation (a), topologically cubic hydrogen-bonding network (b), eight positions of the components and conformations of four trityl groups (c), layered arrangements of 12 benzene rings (d), schematic representation of a censer with a cap and three legs (e), and holes accommodating the ammoniums b between the belt and cap (f) and in the foot (g). (h) Intercluster contact around a 3-fold rotational axis. (i) Head-to-head and tail-totail stacking of the clusters along a 3-fold rotational axis. (j) A packing diagram with 3-fold helical and rotation−inversion axes. The Δ and Λ trityl groups and primary ammonium b are colored in blue, pink, and orange, respectively.

two Δ trityl groups on the upper side and two Λ trityl groups on the lower side is equal to each other. Therefore, the cluster loses chirality as a whole and has an inversion center at the center of the HB core. The hole for one molecule of ammonium a is constructed by three benzene rings: two from the upper or lower layer and one from the middle layer. The achiral clusters assemble by facing two Δ trityl groups of one cluster and two Λ trityl groups of another cluster with inversion centers between them (Figure 6h). The clusters stack in a head-to-tail manner to form a column along the c axis without any shifts in the same manner as the crystal of the TPAA-d (Figure 6i). The columns are bundled along the a and b axes as well as the (a + b)/2 direction with a half pitch translation, generating 2-fold helices along the a and b axes (Figure 6j). The two-component cluster of TPAA-b1 has the CS-type HB network with a 3-fold rotational axis.11 Figure 7a shows one of this enantiomeric clusters with a space-filling representation. The 3-fold rotational axis (Figure 7b) results in the disorder of one trityl group and the opposite isobutyl group. The axis and positions of eight edges (Figure 7c) show that the cluster belongs to a trans-bicapped octahedron with a 3-fold rotational axis. The four trityl groups are separated into a cap with one

trityl group and a belt with three trityl groups. The latter three trityl groups have chiral conformations with one handedness (Δ:Λ = 3:0), whereas the former trityl group of the cap has the opposite conformation. In total, the trityl groups have a chiral combination of the conformations (Δ:Λ = 3:1). Therefore, the cluster has a topographically (conformationally) chiral shell and a topologically achiral HB core; thus, it is chiral as a whole. The cluster in Figure 7a is right-handed, while the other enantiomeric cluster is left-handed (Supporting Information, Figure S12). The 12 benzene rings are divided into three layers: an upper cap with three rings, a middle body with six rings, and a lower foot with three rings (Figure 7d). Such an architecture resembles a traditional censer with a cap and three legs (Figure 7e). One molecule of ammonium b in the hole between the cap and belt is surrounded by three benzene rings: one and two of the upper and middle layers, respectively (Table 1, Figure 7f), while one molecule in the foot is surrounded by three benzene rings of the lower layer (Table 1, Figure 7g). The enantiomeric clusters are assembled using the Δ and Λ trityl groups, generating an inversion center (Figure 7h). The enantiomeric clusters further assemble along the c axis in a head-to-head/tail-to-tail manner to afford a column with a 663


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Figure 8. A two-component cluster of TPAA-b2 (the intermediate of a triangular dodecahedron and trans-bicapped octahedron) with a deformed intermediate structure; one cluster with a space-filling representation (a), topologically cubic hydrogen-bonding network (b), eight positions of the components and conformations of four trityl groups (c), layered arrangements of 12 benzene rings (d), schematic representation of a boat with an irregular structure (e), and holes accommodating the ammoniums b in side-1 (f) and in side-2 (g). (h) Intercluster contact around an inversion center. (i) Stacking of the clusters in a 2-fold helical manner along the b axis. (j) A packing diagram with 2-fold helical axes. The Δ,Λ, the intermediate of Δ and Λ (ΔΛ) trityl groups, and ammonium b are colored in light blue, pink, dark purple, and orange, respectively.

3-fold rotation−inversion axis (Figure 7i). The columns are further bundled to form a racemic compound (Figure 7j). The two-component cluster of TPAA-b2 has a peculiar intermediate structure.6 Figure 8a shows one of the enantiomeric clusters with a space-filling representation. The other enantiomeric cluster is shown in Supporting Information, Figure S13. The C1(b)/C1(b)′-type HB network indicates a deformed structure with no rotational axis (Figure 8b). The relative positions of the eight edges (Figure 8c) show that the cluster may be a deformed intermediate between a triangular dodecahedron and trans-bicapped octahedron. Remarkably, the four trityl groups have two Δ, one Λ, and one intermediate conformation with a pseudomirror plane (Figure 8d). The intermediate conformation resembles the intermediate of a two-ring-flip mechanism from right-handed to left-handed (and vice versa).13 When the intermediate changes to Δ or Λ, the cluster may be transformed to a triangular dodecahedron or trans-bicapped octahedron, respectively. The cluster looks like a boat (Figure 8e). Two molecules of the ammoniums b in the upper belt is accommodated in a hole with three benzene rings: two and one of the upper and middle layers, respectively (Table 1, Figure 8f), while the other two molecules of the lower belt are accommodated in a hole constructed by five benzene rings:

one, two, and two of the upper, middle, and lower layers, respectively (Table 1, Figure 8g). The enantiomeric clusters are assembled using the Δ and Λ trityl groups, generating an inversion center (Figure 8h). The one-handed clusters stack along the b axis in a 2-fold helical manner with a slight shift along the c axis (Figure 8i), in which the stacking manner is different from the other binary systems. The difference can be attributed to the presence of the trityl group with an intermediate conformation of Δ and Λ. The helical columns are bundled along the a and c axes with 2-fold helical axes and inversion centers, respectively, between the columns, thus affording a racemic compound (Figure 8j).

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CONCLUSION In conclusion, the metal-free supramolecular (4 + 4) clusters of organic salts involving trityl groups are distorted from cubes, affording the analogues of the octacoordinated polyhedrons such as triangular dodecahedrons, trans-bicapped octahedrons, and square antiprisms. This distortion results from the steric factor: the ammonium components comprising 12 benzene rings of the four trityl groups form different arrangements. The three-component polyhedrons generate supramolecular chirality in the shells due to the one-handed combinations of the 664


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(6) (a) Yuge, T.; Tohnai, N.; Fukuda, T.; Hisaki, I.; Miyata, M. Chem.Eur. J. 2007, 13, 4163−4168. (b) Sasaki, T.; Ida, Y.; Hisaki, I.; Yuge, T.; Uchida, Y.; Tohnai, N.; Miyata, M. Chem.Eur. J. 2014, 20, 2478−2487. (7) (a) Tohnai, N.; Mizobe, Y.; Doi, M.; Sukata, S.; Hinoue, T.; Yuge, T.; Hisaki, I.; Matsukawa, Y.; Miyata, M. Angew. Chem., Int. Ed. 2007, 46, 2220−2223. (b) Yamamoto, A.; Hamada, T.; Hisaki, I.; Miyata, M.; Tohnai, N. Angew. Chem., Int. Ed. 2013, 52, 1709−1712. (8) (a) Yuge, T.; Kai, N.; Hisaki, I.; Miyata, M.; Tohnai, N. Chem. Lett. 2007, 36, 1390−1391. (b) Kobayashi, Y.; Morisawa, F.; Saigo, K. Org. Lett. 2004, 6, 4227−4230. (9) (a) McDonald, S.; Ojamäe, L.; Singer, S. J. J. Phys. Chem. A 1998, 102, 2824−2832. (b) Ugalde, J. M.; Alkorta, I.; Elguero, J. Angew. Chem., Int. Ed. 2000, 39, 717−721. and references therein. (c) Belair, S. D.; Francisco, J. S. Phys. Rev. A 2003, 67, 0632006 and references therein. (10) (a) Okamoto, Y.; Honda, S.; Yashima, E.; Yuki, H. Chem. Lett. 1983, 1221−1224. (b) Nakano, T.; Okamoto, Y. Chem. Rev. 2001, 101, 4013−4038. (11) (a) Sada, K.; Watanabe, T.; Miyamoto, J.; Fukuda, T.; Tohnai, N.; Miyata, M.; Kitayama, T.; Maehara, K.; Ute, K. Chem. Lett. 2004, 33, 160−161. (b) Yuge, T.; Hisaki, I.; Miyata, M.; Tohnai, N. CrystEngComm 2008, 10, 263−266. (12) Crystallographic data for TPAA-ac, TPAA-ad, TPAA-bc, TPAA-bd and TPAA-d. For TPAA-ac: C48H54N2O4, Mw= 722.97, a = 13.4190, b = 25.7360, c = 24.7980 Å, α = 90, β = 100.6840, γ = 90°, V = 8415.5628 Å3, T = 213.1 K, monoclinic, space group C2/c (No. 15), Z = 8, ρcalcd = 1.141 g/cm3, no. of measured (and independent) reflections: 44825 (7630), the final R1 and wR2 values 0.0725 (I > 2σ(I)) and 0.2460 (all data), respectively, and GOF = 1.004. For TPAA-ad: C49H56N2O4, Mw = 736.99, a = 13.4479(4), b = 25.9325(8), c = 24.8064(8) Å, α = 90, β = 100.9237(14), γ = 90°, V = 8494.2(5) Å3, T = 213.1 K, monoclinic, space group C2/c (No. 15), Z = 8, ρcalcd = 1.153 g/cm3, no. of measured (and independent) reflections: 39474 (7692), the final R1 and wR2 values 0.1100 (I > 2σ(I)) and 0.3674 (all data), respectively, and GOF = 1.206. For TPAA-bc: C48H54N2O4, Mw = 722.97, a = 13.5015(3), b = 25.7288(6), c = 24.7927(6) Å, α = 90, β = 100.8180(12), γ = 90°, V = 8459.4(4) Å3, T = 213.1 K, monoclinic, space group C2/c (No. 15), Z = 16, ρcalcd = 1.135 g/cm3, no. of measured (and independent) reflections: 40767 (7699), the final R1 and wR2 values 0.1164 (I > 2σ(I)) and 0.2956 (all data), respectively, and GOF = 1.421. For TPAA-bd: C49H56N2O4, Mw = 736.99, a = 13.5129(12), b = 25.861(2), c = 24.783(2) Å, α = 90, β = 100.788(4), γ = 90°, V = 8507.7(13) Å3, T = 213.1 K, monoclinic, space group C2/ c (No. 15), Z = 8, ρcalcd = 1.151 g/cm3, no. of measured (and independent) reflections: 30657 (7409), the final R1 and wR2 values 0.1240 (I > 2σ(I)) and 0.3746 (all data), respectively, and GOF = 0.931. For TPAA-d: C50H58N2O4, Mw = 751.02, a = 24.9643(6), b = 14.9519(3), c = 26.8128(6) Å, α = 90, β = 119.0841(12), γ = 90°, V = 8746.3(3) Å3, T = 213.1 K, monoclinic, space group C2/c (No. 15), Z = 8, ρcalcd = 1.141 g/cm3, no. of measured (and independent) reflections: 19235 (7236), the final R1 and wR2 values 0.1038 (I > 2σ(I)) and 0.3738 (all data), respectively, and GOF = 1.083. (13) Glaser, R. In Acrylic Organonitrogen Stereodynamics; Lambert, J. B., Takeuchi, Y., Eds.; VCH: New York, 1992; pp 123−148.

twist conformations of four trityl groups. One of the twocomponent polyhedrons forms the chiral trans-bicapped octahedron with preferential combinations of the conformations. This result indicates that organic clusters can be used to generate and introduce supramolecular chirality based on the characteristic combinations of their components.

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ASSOCIATED CONTENT

S Supporting Information *

Details of preparation procedures and X-ray crystallographic studies on the supramolecular clusters with cubic hydrogen bonding networks, infrared measurements, crystallographic data in CIF format, additional crystal structures. This material is available free of charge via the Internet at http://pubs.acs.org. Crystallographic information files are also available from the Cambridge Structural Data Center (CCDC) (http://www. ccdc.cam.ac.uk, CCDC numbers: CCDC 973399 (TPAA-ac), 973398 (TPAA-ad), 973397 (TPAA-bc), 973396 (TPAA-bd), and 973395 (TPAA-d)).

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AUTHOR INFORMATION

Corresponding Authors

(T.S.) *E-mail: [email protected]. (M.M.) *E-mail: [email protected]. Present Address ‡

The Institute of Scientific and Industrial Research, Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka 567-0047, Japan.

Notes

The authors declare no competing financial interest.

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ACKNOWLEDGMENTS This work was financially supported by Grant-in-Aid for Scientific Research B (24350072, 25288036) and Grant-in-Aid for Scientific Research on Innovative Areas (24108723) from MEXT and JSPS, Japan. T.S. acknowledges Grant-in-Aid for JSPS Fellows (25763), the GCOE Program of Osaka University and Grants for Excellent Graduate Schools, MEXT, Japan.

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ABBREVIATIONS HB, hydrogen bonding; TPAA, triphenylacetic acid REFERENCES

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