Synthesis, spectroscopic properties and DFT calculations of a novel multipolar azo dye and its zinc(II) complex

The synthesis and photophysical properties of 5-(diethylamino)-4-[(E)-(4-nitrophenyl)diazenyl]-2-(1,3-benzoxazol-2-yl)phenol (AB-HBO) and its zinc complex were examined. The organic molecule acts as a pH sensitive chromophore and as mononegative ligand for zinc(II) ion. Structural features and photophysical properties of AB-HBO were studied. The solvatochromic blue shift, shown by the ligand in its neutral form, is widely enhanced in its deprotonated form. The color solution ranges from red-orange to violet and blue-green as function of the electronic density deformation. Fluorescence spectra were recorded on both ligand and zinc complex solutions. (TD)DFT calculations have been performed to rationalize the absorbance of chromophore and complex.