Negative solvatochromic behavior and theoretical investigation on 2-amino-4-(4-(dimethyl amino)phenyl)buta-1,3-diene-1,1,3-tricarbonitrile

Abstract

In the present work, 2-amino-4-(4-(dimethylamino)phenyl)buta-1,3-diene-1,1,3-tricarbonitrile (AMAPB), a polyfunctional compound, which can serve as a solvatochromic probe, was obtained via condensation of malononitrile dimers with N,N-dimethylamino benzaldehyde. The influence of solvent polarity on the absorption spectra of the synthesized compound was investigated. The spectral characteristics in different solvents at room temperature were analyzed. We discuss how variables, including the empirical solvent polarity ET (30), (π*, α, β) and (SA, SB, SPP) contribute to solute-solvent interactions. A multi-parameter regression models for quantitative assessment of the solute/solvent interaction and the absorption has been used to explain the solvent effect. DFT and TD-DFT calculations coupled with the polarizable continuum model (PCM) were performed to investigate the solvent-dependent spectral and geometrical properties of AMAPB. The calculations exhibited good agreements with the experimental results using the B3LYP/6–31+ G ** functional. The delocalization and intramolecular charge transfer are calculated and discussed in terms of natural bond orbital analysis (NBO) and second-order perturbation interactions between donor and acceptor MOs. The calculated E HOMO and E LUMO energies were used to calculate the global properties such as electronic chemical potential (μ), chemical hardness (η), global electrophilicity index (ω), nucleophilicity index (N), and global softness (S). Experimental and theoretical results promoted that the chemical properties of AMAPB are dependent on the polarity of the chosen solvent and its hydrogen bonding capability.