Electronic investigation of light-induced reversible coordination of Co(II)/spiropyran complex

Herein, synthesis and characterization of a cobalt (II) complex using a spiropyran as its ligand was described. Solid complex (CoMC) was obtained using a novel ultraviolet radiation-induced precipitation technique, FTIR-ATR spectroscopy demonstrated the binding sites involved in the coordination. Computational calculations were crucial to understand the experimental results, demonstrating the frontiers orbitals in tetrahydrofuran. Moreover, mass spectrometry revealed a 1:2 Co(II)ligand stoichiometry. By means of UV-vis absorption spectroscopy, complexation was confirmed and photochromic and the solvatochromic characteristics of the complex and the free ligand were studied. These results showed that the complex did not present a would be expected pattern regarding its solvatochromic properties, while the free ligand did. Reversibility experiments exposed a high resistance to photodegradation of the complex in isopropanol, comparing to the other solvents tested.