A computational study on the excited state properties of a cationic cyanine dye: TTBC

Abstract

a b s t r a c tThe ground and excited state behaviors of a biologically important mitochondria selective dye, 5,5 0 ,6,6 0 -tetrachloro-1,1 0 ,3,3 0 -tetraethyl-benzimidazolo carbocyanine (TTBC), were investigated in order to give useful information related to the enhancement of its electronic and optical properties. DFT and TDDFT levels of theory with different functionals and basis sets were used. The results obtained by using PBEPBE/6-31+G(d,p)/C-PCM are in good agreement with the experiments. The potential energy surface sections of TTBC were explored and the geometry optimized in the first excited state, S 1 , to analyze the fluorescence spectrum of the dye. There are two distinct minima on the S 1 surface, one located near the ground state geometry and an energetically favorable twisted geometry, having a charge transfer character. The observation of similar ground and excited state dipoles as well as solvent-independent fluorescence and absorption wavelengths reveals that there is no competition between the two minima; the emission is dominantly coming from the more planar configuration.

Theoretical calculation of the maximum absorption wavelength for Cyanidin molecules with several methodologies

“…For the CyCl molecule the change when the basis set is extended remains in 4 nm and the largest alteration is found around 30 nm and the B3LYP functional is used. The use of higher order polarizations and diffuse functions were explored by other authors in cyanine dyes and the change was not larger than 11 nm and the computational time was considerably increased [33]. For this reason we decided to test only the 6-31G(d) and 6-31+G(d,p) basis set for the seven functionals defined for the TD-DFT calculations.…”

Molecular design of near infrared polymethine dyes: A review

“…They enable one to perform design of new perspective dye molecules with required spectral and other properties. Recent approaches take into consideration many features of the charged π-electron systems of PMDs [62][63][64][65][66] and hence make it possible to understand comprehensively the nature of the electron transitions within dye molecules.…”

Unsymmetrical Relaxation Paths of the Excited States in Cyanine Dyes Detected by Time-Resolved Fluorescence: Polymethinic and Polyenic Forms

“…Of course, there is no perfect coinciding of the calculated and experimental data that is typical for polymethine dyes. [27][28][29] However the modelling substantially supplements the experimental analysis of electron transitions and relaxation paths in the AF molecule.…”