Abstract

The synthesis and spectroscopic characterization of two new N,N-bis(pyridin-2-ylmethyl)-4-(X-diazenyl)aniline (X: A = CH3, B--CN) chemosensors were carried out. Both compounds are yellow in H2O/CH3CN solution as a free ligand. Upon contact with Cu2+ cations, the solution becomes colorless. UV-Vis absorption studies of the sensors show that this color change is due to the Cu2+ interaction with the sensor with 1:1 stoichiometry, causing a blue shift of the characteristic band, and high selectivity. In addition, theoretical calculations were performed using time-dependent density functional theory (TDDFT) and Morokuma-Ziegler decomposition analysis. The theoretical results display a good correlation with the experimental data. The transition pi ->pi*is evidenced as characteristic of the free sensor and the complexes formed by the sensor and metals. Other metal ions (different from copper) were also experimentally and theoretically studied. Only the Cu2+ complexes showed an increase in the band intensity at 312-323 nm displaying an LMCT character (pi -> 3dx2-y2)) with a strong contribution of the 3d molecular orbitals of Cu2+ ions.