UV-absorbing benzamide-based dendrimer precursors: synthesis, theoretical calculation, and spectroscopic characterization

Abstract

The ability to tune the structural properties with respect to size, polarity, and terminal functionalities makes dendrimers a highly attractive class of compounds with potential biological and catalytic applications. In the present study, Janus (J) and Twin (T) benzamide-based branched structures were synthesized from a primary precursor of methyl gallate and then further characterized using spectroscopic and theoretical techniques. The optimized structures of these dendrimer precursors at the B3LYP/6-311G(d) level revealed that the aliphatic chains in the most stable forms are oriented in the least strained arrangement with the (–benzene–O–CH₂−) linkage adopting the phenol-like configuration. UV–Vis spectra showed a consistent absorption at nearly 290 nm, suggesting that both molecules absorb within the ultraviolet region and are colorless. Prominent bands, which include the –OH vibrational stretch, the –CC– stretch, the –CO stretch, the –C–O in-plane stretch, and the –NH in-plane bending, were assigned and correlated with the structural and electronic aspects of the molecules.