Generation and solid state characterization of tetrapyridinium perchlorate salts derived from tetrapyridyl tetraphenylethylenes

Two tetraarylethylene derivatives symmetrically functionalized at the 4, 4′, 4″, and 4‴4‴ positions with either 4-pyridyl or 3-pyridyl groups were converted to their corresponding tetrapyridinium perchlorate salts upon exposure to Fe(ClO4)3·xH2O. These tetra-perchlorates were isolated as single crystals and their structures were determined by X-ray diffractometry. In both cases extensive hydrogen bonding networks were observed involving pyridinium N–H groups, perchlorate anions, and included water molecules. Additionally, both structures feature hydrophobic crystalline regions formed from stacking of tetraarylethylene cations in helical fashion. Polar pyridinium N–H groups are directed outward from these stacks into hydrophilic crystalline regions containing perchlorate anions and water molecules of hydration. Information obtained regarding the solid state structures of these functionalized tetraarylethylene derivatives should prove useful in design of more elaborate supramolecular architectures.

► Pyridinium tetraphenylethylenes have been structurally characterized.
► Solid state H-bonding networks involving N–H+, ClO4-, and H2O.
► Tetraarylethylenes form helical stacks with polar N–H groups toward the periphery.
► Helical stacks surrounded by polar regions of ClO4- and H2O.