Experimental (FT-IR, FT-Raman and UV–Vis) spectra and theoretical DFT investigations of 2,3-diaminophenazine

Vibrational analysis of the planar electron-rich heterocyclic 2,3-diaminophenazine (DAP) molecule was carried out using FT-IR and FT-Raman spectroscopic techniques. The equilibrium geometry, harmonic vibrational wavenumbers, various bonding features have been computed using density functional method. The calculated molecular geometry parameters have been compared with XRD data. The detailed interpretation of the vibrational spectra has been carried out. The first order hyperpolarizability (β0) of the molecular system and related properties (β, α0 and Δα) of DAP are calculated using HF/6-31G(d,p) method on the basis of finite-field approach. Vibrational analysis reveals that the simultaneous IR and Raman activation of the C–C stretching mode in the molecule provide the evidence for the charge transfer interaction takes place from electron donating group to the ring. The energy and oscillator strength calculated by time-dependent density functional theory (TD-DFT) results complements with the experimental findings. The simulated spectra satisfactorily coincide with the experimental spectra.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► A detailed interpretation of Infrared and Raman spectra of DAP were reported. ► The first order hyperpolarizability of DAP were calculated. ► NBO, HOMO and LUMO analysis were also performed by DFT approach.