A Benzimidazo[1,2-c]quinazoline Derivative as a Precursor for Schiff Base Cu(II) Complex: Synthesis, Spectroscopic and Photophysical Insights

In this work, a benzimidazo[1,2-c]quinazoline derivative (3) was synthesized and shown to act as a versatile precursor that can be transformed into a Schiff base upon coordination with Cu(II), yielding the corresponding Cu(II) complex 4b. The influence of this metal coordination on photophysical properties was subsequently investigated. The full characterization data for compound 3 were obtained using MALDI-TOF MS, 1H and 13C NMR (1D and 2D), FT-IR, and elemental analysis. In addition, the crystal structure of 3 was elucidated by the single-crystal X-ray diffraction method for the first time. The structure of Cu(II) complex 4b was proposed and supported by spectroscopic methods (MALDI-TOF MS, FT-IR) and elemental analysis. The photophysical properties of the targeted compounds (3 and 4b) were investigated using UV-Vis and fluorescence spectroscopies in various organic solvents, and their results were compared. In addition, thermogravimetric analyses of compound 3 and Cu(II) complex 4b were performed to evaluate the contribution of metal coordination to thermal stability.