Density functional theory characterisation of 4-hydroxyazobenzene

Abstract

We report the structural properties, infrared (IR) and Raman spectra, dipole moment, polarisability, hardness and chemical potential of the trans and cis configurations of 4-hydroxyazobenzene calculated using the B3LYP functionals. All calculations were performed with the following basis sets: 6-31G, 6-31++G, 6-31G(d,p), 6-31++G(d,p), 6-31G(2d,2p), 6-31++G(2d,2p) and 6-311++G(2d,2p). We observed that 6-31++G(d,p) gives similar results to 6-311++G(2d,2p). Consequently, SVWN and PW91 methods were also used in association with 6-31++G(d,p) to test the influence of the different models of exchange and correlation functionals. A planar structure was obtained for all the optimised trans configuration structures. In both isomers, the presence of the hydroxyl group leads to an asymmetry in certain structural parameters. From these results, two IR or Raman active frequencies can be used to easily distinguish trans and cis configurations. The trans configuration was found to be more stable than the cis configuration by 67 +/- 2 kJ mol(-1) at 0 K. The difference of the dipole moment between trans and cis for 4-hydroxyazobenzene was found to be lower than for trans and cis azobenzene.

Vibrational analysis of [4-[(E)-phenylazo] phenyl]ethanol based on the comparison between the experimental and DFT calculated Raman spectra

“…From a numerical point of view, the Raman intensities, as a function of the third derivatives of the energies, are both dependant on the energetic models (basis set truncation, treatment of electron correlation), the methods and the parameters used to calculate the analytical and numerical derivatives [60]. Regarding azobenzene derivatives, different theoretical studies were performed with the aim of improving the assignment and the description of the normal modes [43][44][45][46][47][48][49][50][51]. Different methods were tested and although some important information was extracted, the questions concerning the chemistry models still remain open.…”

“…-5 au and a rms force less than 3⋅10 -4 au Based on our previous work on 4-[(E)-phenylazo]phenol [47], we tested two basis sets: 6-31G++(d,p) and 6-311G++(2d,2p). The Raman spectra obtained were calculated with the different parameters used by default on the optimized structures.…”

“…The N=N stretching vibration, characteristic of the azobenzene group, can be involved in several vibrational bands, which makes the assignment of the Raman spectra more difficult. Consequently, from the middle of the 90's, theoretical studies were performed to improve the assignment and description of the normal modes in azobenzene and their derivatives [43][44][45][46][47][48][49][50][51]. In this study, we assessed the capacity of the B3LYP/6-311++G(2d,2p) method to reproduce the .…”

Density functional theory calculations on azobenzene derivatives: a comparative study of functional group effect

“…We used 6-31++G(d,p) basis set, which is the most appropriate in terms of time, accuracy, and cost of computing resources for thé´F ig. 1 Structure of trans configuration of molecules studied determination of electronic properties [8]. Geometry parameters for each structure were free of constraints and allowed to relax during the optimization process.…”

“…The aim of this research is to investigate the effect of substituents of a group of eight azobenzene derivatives in trans and cis forms on structural and electronic properties by DFT method, which was widely and successfully used in studies concerning structural and electronic properties of azobenzene derivatives [6][7][8].…”