Theoretical investigation on the effect of protonation on the absorption and emission spectra of two amine-group-bearing, red push-pull emitters, 4-dimethylamino-4′-nitrostilbene and 4-(dicyanomethylene)-2-methyl-6- p -(dimethylamino) styryl-4H-pyran, by DFT and TDDFT calculations

Petsalakis, I. D., Georgiadou, D. G., Vasilopoulou, M., Pistolis, G., Dimotikali, D., Argitis, P. and Theodorakopoulos, G. (2010) Theoretical investigation on the effect of protonation on the absorption and emission spectra of two amine-group-bearing, red push-pull emitters, 4-dimethylamino-4′-nitrostilbene and 4-(dicyanomethylene)-2-methyl-6- p -(dimethylamino) styryl-4H-pyran, by DFT and TDDFT calculations. Journal of Physical Chemistry A, 114 (17), 5580-5587. (doi:10.1021/jp100338d).

Abstract

A theoretical investigation on the electronic structure of 4-dimethylamino-4′-nitrostilbene (DANS), 4-(dicyanomethylene)-2-methyl-6- p-(dimethylamino) styryl-4H-pyran (DCM), and their protonated forms is presented in an effort to rationalize recent experimental results on the tuning of the emitted color of organic light-emitting diodes through photochemically induced protonation. Density functional theory (DFT) and time-dependent density functional theory (TDDFT) calculations have been carried out on the neutral and protonated forms of DANS and DCM, employing both the B3LYP and the CAM-B3LYP functionals. It was found that the CAM-B3LYP functional leads to better agreement than the B3LYP of the calculated with the experimental absorption λ_max for DANS, whereas B3LYP is more appropriate than CAM-B3LYP for DCM. The results of the calculations aid in a rationalization of the observed differences of the spectra of DANS and DCM upon protonation, and in particular those differences that make DANS a more attractive system for absorbance and emission tuning.

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Contributors

Author: D. G. Georgiadou

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