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1,2,3,4-Tetrakis(carboxyphenyl)benzene (CPB) forms a predictable ladder-shaped porous motif through intermolecular hydrogen-bonding of the carboxy groups. The stacking manner of the ladder motif, on the other hand, cannot be controlled, yielding a crystal structure with discrete inclusion spaces. To modulate the stacking manner, its derivative CPB(OMe) with methoxy substituent groups at 5,6-positions was synthesized and crystallized to yield a crystalline hydrogen-bonded organic framework (HOF), in which the ladder motifs are stacking with a different manner to form 1D inclusion channels, instead of discrete voids. Because of the channel structure, removal of the included solvent molecules can be easily conducted, and the resultant activated HOF CPB(OMe)-a exhibited micropores with BET surface area of 199 m 2  g -1 , which is larger than that of the other HOF CPB-a., (© 2024 Wiley-VCH GmbH.)

The on-surface self-assembled behavior of four C 3 -symmetric π-conjugated planar molecules (Tp, T12, T18, and Ex) has been investigated. These molecules are excellent building blocks for the construction of noncovalent organic frameworks in the bulk phase. Their hydrogen-bonded 2D on-surface self-assemblies are observed under STM at the solid/liquid interface; these structures are very different to those in the bulk crystal. Upon combining the results of STM measurements and DFT calculations, the formation mechanism of different assemblies is revealed; in particular, the critical role of hydrogen bonding in the assemblies. This research provides us with not only a deep insight into the self-assembled behavior of these novel functional molecules, but also a convenient approach toward the construction of 2D multiporous networks., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Transformation with every fiber of its being: Dehydrobenzoannulene derivatives with a boomerang shape, dipole moment, and substituents that make diverse interactions enable the construction of stimuli-responsive nanofibers despite the lack of stimuli-responsive groups in these compounds. Interestingly, the supramolecular nanofibers obtained after ultrasonic treatment displayed an 80% decrease in conductivity as compared to untreated nanofibers. This is the first example of an electronic wire for which the conductivity can be controlled by ultrasound., (Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Quinine, one of Cinchona alkaloids, has been of great interest from medical, synthetic, and supramolecular viewpoints. However, unaccountably, the guest-free (GF) crystal of quinine containing no solvent or other molecules has not been reported for nearly three decades, although GF crystals of other Cinchona alkaloids, such as quinidine, cinchonidine, and cinchonine, are already known. In this study, we successfully revealed the crystal structure of quinine, which belongs to the P2(1) space group with the cell parameters of a=6.0587(1), b=19.2492(5), c=22.2824(7) Å, β=92.1646(11)°, and V=2596.83(12) Å(3). Interestingly, the crystal has three crystallographically independent molecules in the cell (Z'=3) that are connected through a N(quinoline)⋅⋅⋅H-O hydrogen bond to form a pseudo three-two-fold (3(2)) double-helical motif. The helical motif is completely different from those observed in GF crystals of other Cinchona alkaloids. Hierarchical comparison on the crystal structures of a series of Cinchona alkaloids including quinine clearly demonstrated that only small structural differences of a molecule, particularly the position of the vinyl group, cause a significant variety of assembly manner in the crystalline state. There have been no reports systematically demonstrating such steric effect in crystals of Cinchona alkaloids, and, therefore, the present system contributes to the design of desired functional crystal structures., (Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Achiral molecules can form aggregates with chirality. This depends on the relative position of the molecules, in other words, the tilt of the molecules (so-called supramolecular tilt chirality). In this paper, we describe supramolecular chirality appearing in a 2(1) column composed of symmetrical benzene molecules, which is formed in the host cavity of inclusion crystals of cholic acid. Moreover, we determined the handedness, that is, right or left, of the 2(1) helical column of benzene on the basis of the molecular tilt. Determination of the 2(1) helical handedness was performed on assemblies of other benzene derivatives in cholic acid crystals and benzene assemblies in other host frameworks selected from the Cambridge Structural Database. Finally, we demonstrated complementarity of the handedness between the 2(1) symmetrical host framework of cholic acid and the benzene column.