Organo- and Hydrogelators Based on Luminescent Monocationic Terpyridyl Platinum(II) Complexes with Biphenylacetylide Ligands

摘要

A series of phosphorescent terpyridyl platinum(II) complexes with ancillary biphenylacetylide ligands, namely, [(R_(3)tpy)PtC (ident to) C(biphenyl)]X (R velence tBu, H, or Et_(2)N; tpy velence 2,2';6',2"-terpyridyl; X is an anion) were synthesized and structurally characterized by various spectroscopic techniques and X-ray diffraction methods. Despite a lack of long alkyl chain(s) or hydrogen-bonding motif(s), complexes [(tpy)PtC (ident to) C(biphenyl)]Cl and [(tBu_(3)tpy)PtC (ident to) C(biphenyl)]X (X velence Cl, ClO_(4), PF_(6), or BF_(4)) were found to gelate water and organic solvents, respectively. The self-aggregation of these complexes in solutions and the resulting gels were investigated with variable-temperature (VT) ~(1)H NMR spectroscopy, polarized optical microscopy, and absorption/emission spectroscopy. SEM micrographs on dry gels revealed entangled nanofibers with diameters of 20-40 nm and lengths of tens of micrometers. Powder X-ray diffraction (PXRD) study revealed various degrees of crystallinity of these fibrillar nanostructures. The substituents on both the terpyridyl and acetylide ligands and counterion of these complexes play a profound but concerted role in tuning the intermolecular metal...metal and/or pi-pi interactions, and hence the gelation properties.