Distortion-Controlled Redshift of Organic Dye Molecules.

ABSTRACT: It is shown, quantum chemically, how structural distortion of an aromatic dye molecule can be leveraged to rationally tune its optoelectronic properties. By using a quantitative Kohn-Sham molecular orbital (KS-MO) approach, in combination with time-dependent DFT (TD-DFT), the influence of various structural and electronic tuning parameters on the HOMO-LUMO gap of a benzenoid model dye have been investigated. These parameters include 1)?out-of-plane bending of the aromatic core, 2)?bending of the bridge with respect to the core, 3)?the nature of the bridge itself, and 4)??-? stacking. The study reveals the coupling of multiple structural distortions as a function of bridge length and number of bridges in benzene to be chiefly responsible for a decreased HOMO-LUMO gap, and consequently, red-shifting of the absorption wavelength associated with the lowest singlet excitation (??560?nm) in the model cyclophane systems. These physical insights together with a rational approach for tuning the oscillator strength were leveraged for the proof-of-concept design of an intense near-infrared (NIR) absorbing cyclophane dye at ?=785?nm. This design may contribute to a new class of distortion-controlled NIR absorbing organic dye molecules.

SUBMITTER: Narsaria AK 

PROVIDER: S-EPMC7027851 | biostudies-literature | 2020 Feb

REPOSITORIES: biostudies-literature