Guest-Induced Supramolecular Isomerism and Chirality of Brucine Inclusion Crystals with Aliphatic Alcohols: A Hierarchical Interpretation

Abstract

Cocrystallization of brucine with a series of aliphatic alcohols was systematically investigated to understand molecular recognition through supramolecular isomerism and chirality. Guest-induced supramolecular isomers of brucine were obtained by cocrystallization and were categorized into three structural types based on the common 2 1 helical tapelike assemblies. These supramolecular isomers were elucidated from the molecular structures on the basis of qualitative hierarchical structural analysis through supramolecular chirality. Moreover, it was found that the supramolecular isomerization occurred depending on the size of the guest molecules. This dependence was clearly evaluated on the relationship between the volume of the guest molecules and the packing coefficient of the void spaces in the host cavities.Crystalline host compounds have attracted much attention in the field of crystal engineering and supramolecular chemistry due to practical and fundamental applications in catalysis, magnetism, electro and non-linear optics, chemical separation, gas-storage, and drug delivery.

Supramolecular Chirality in Crystalline Assemblies of Bile Acids and Their Derivatives; Three-Axial, Tilt, Helical, and Bundle Chirality

“…Now our study is spreading from steroidal molecules to the surrounding natural compounds, such as brucine [128], cinchona alkaloids, and further to the surrounding organic substances, such as organic salts [129][130][131]. Supramolecular chirality of assemblies of these substances fascinates us so much.…”

Supramolecular‐Tilt‐Chirality on Twofold Helical Assemblies

“…In the motifs, molecules in front of the helical axis tilt to the right, indicating a right-handed helix. [24] 2 1 Helices of Planar Molecules…”

A Designed Cavity for Zwitterionic Species: Selective Recognition of Taurine in Aqueous Media

“…This complementarity is often difficult to quantify, but in 1998 Rebek et al stated that the phenomena of molecular recognition in organic solutions are often optimal when the packing coefficient (pc), defined as the ratio of the van der Waals volume of the guest to the accessible volume in the cavity of the host, is equal to 55(AE9) %. [36][37][38][39][40][41][42] The van der Waals volumes of the guests 2-12 were calculated by using the method reported by Abraham et al [43] The packing coefficients were then determined and are reported in Table 1. Entries 2 and 6 ( Table 1) show that efficient complexation is observed for zwitterionic guests with very favorable pc values close to 55 % (59 and 51 %, respectively).…”