Cis–trans isomerisation and absorption properties of the ring-extended azobenzene

Abstract

A series of azobenzene derivatives which differ in the number of rings attached to benzene is investigated using dispersion-corrected density-functional theoretical methods. The studies on the effect of extended rings on the energy of cis and trans isomers (ΔE_cis–trans) of the derivatives revealed that ΔE_cis–trans is increased from azobenzene to azoanthracene, however, decreased when the rings are extended in two dimensions. The time-dependent density-functional theoretical studies showed that the extension of rings in two-dimension shifts absorption maximum from ultraviolet to visible region. The investigations on fluorine and amino-substituted derivatives of azocoronene showed its cis isomer as lower in energy than trans isomer.

GRAPHICAL ABSTRACT

KEYWORDS:

• Azobenzene
• cis–trans isomerisation
• opto-electronic properties
• reorganisation energy

Acknowledgments

AD acknowledges the Ministry of Education, India for a research fellowship. The authors acknowledge Indian Institute Technology Roorkee for the infrastructure.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

CNR is grateful to the Science and Engineering Research Board (SERB) [grant number EMR/2016/008024].