Synthesis, Characterization, Optical, Electrochemical, and Theoretical Studies of Substituted Terpyridines

Abstract

In order to study the effect of substituents on the terpyridine molecular system, a series of substituted 2,2:6′,2″-terpyridines have been synthesized and fully characterized. The substitutions range from EWGs like –F to EDGs like –OMe, -NMe2, triphenylamine (TPA), heterocycles like furan and fused rings like anthracene. The –F, -OMe, and -NMe2 are connected to the terpyridine core via phenyl ring as spacer group whereas the TPA is attached via thienyl moiety. The furan and anthracene are directly appended to the terpyridine core. The synthesized terpyridines were structurally characterized with NMR and mass spectrometry. The terpyridines were then subjected to UV–Vis absorption, luminescence, and potentiometric analysis. An extension of the light harvesting window was observed for terpyridines with electron-donating groups (EDGs) as substituent. Density functional theory (DFT) based methods (B3LYP model with 6–311 G basis sets) were applied to optimize the molecular structures. The experimental absorption studies were simulated with TD-DFT based theoretical calculations (B3LYP with 6–311 G (d,p) basis set in DCM solvent using IEFPCM model) to ascertain the underlying electronic transitions. The findings were then used to define the structure-activity relationship.