Improving the optical properties of [14] and [18] annulenes sandwiched between electron donor-acceptor groups

Abstract

In the present research, an electron donor-acceptor compound (called push-pull systems) were studied using DFT methods in the vacuum space. We used [14] annulene and [18] annulene as π conjugated system and connected methoxy diphenylamine group as an electron donor and cyanoacrylic acid as an electron acceptor group. It was shown that the donor and acceptor groups narrowed the Eg of structure which is the result of hyperconjugation. Pristine annulenes had intensive light absorption in the ultraviolet region in electromagnetic radiation. After both molecules sandwiched between electron donor-acceptor groups, a significant redshift from the UV region to the visible and IR region was observed. Also in NMR calculation, it was observed the amount of aromaticity has increased after sandwiching. In all IR and Raman spectrum, it was shown the amount and intensity of light absorption increased after placing annulenes in electron donor-acceptor groups. The results of this research may be useful in designing new materials applicable as photosensitizers and photodynamic therapy.