Synthesis, Spectroscopic, Electrochemical and Pb2+-Binding Studies of Tetrathiafulvalene Acetylene Derivatives

TLDR: Spectroscopic and electrochemical behaviors of the tetrathiafulvalene acetylene derivatives demonstrate that the TTF unit interacts with the electron-accepting group through the triple bond, thus leading to the intramolecular charge transfer.

Abstract: A series of tetrathiafulvalene acetylene derivatives, [TTF−C⋮C−A] [A = C6H4N(CH3)2-4 (1), C6H4OCH3-4 (2), C6H5 (3), C6H4F-4 (4), C6H4NO2-4 (5), C5H4N-2 (6), C5H4N-3 (7), and C5H4N-4 (8)], have been designed and synthesized to provide insight into the nature of the donor−acceptor interaction via a π-conjugated triple bond. The X-ray crystal structure of [TTF−(C⋮C)−C6H4OCH3-4] (2) reveals that the phenyl ring linked by acetylene is almost coplanar to the plane of TTF with a dihedral angle of 3.6°. The strong intermolecular C−H···O hydrogen bonding was found to direct the molecular helical assemblies with a screw pitch of 5.148 A when viewed along the a-axis. Spectroscopic and electrochemical behaviors of the tetrathiafulvalene acetylene derivatives demonstrate that the TTF unit interacts with the electron-accepting group through the triple bond, thus leading to the intramolecular charge transfer. The pyridine-substituted TTF compounds 6−8 show remarkable sensing and coordinating properties toward Pb2+. Comp...