Synthesis, Crystal Structure, Spectroscopic Characterization, DFT Calculations and Cytotoxicity Assays of a New Cu(II) Complex with an Acylhydrazone Ligand Derived from Thiophene

RODRÍGUEZ, MARÍA R.; BALSA, LUCÍA M.; PIRO, OSCAR E.; ETCHEVERRÍA, GUSTAVO A.; GARCÍA-TOJAL, JAVIER; PIS-DIEZ, REINALDO; LEÓN, IGNACIO E.; PARAJÓN-COSTA, BEATRIZ P.; GONZÁLEZ-BARÓ, ANA C.

Inorganics

MDPI,

Lugar: Basel; Año: 2021 vol. 9

Anew Cu(II) complex is synthetized by the reaction of copper nitrate and aN-acylhydrazoneligand obtained from the condensation of o-vanillin and 2-thiophecarbohydrazide (H2L). The solidstatestructure of [Cu(HL)(H2O)](NO3)H2O, or CuHL for simplicity, was determined by X-raydiffraction. In the cationic complex, the copper center is in a nearly squared planar environmentwith the nitrate interacting as a counterion. CuHL was characterized by spectroscopic techniques, includingsolid-state FTIR, Raman, electron paramagnetic resonance (EPR) and diffuse reflectance andsolution UV-Vis electronic spectroscopy. Calculations based on the density functional theory (DFT)assisted the interpretation and assignment of the spectroscopic data. The complex does not showrelevant antioxidant activity evaluated by the radical cation of 2,20-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) method, being even less active than the free ligand as aradical quencher. Cytotoxicity assays of CuHL against three human tumor cell lines, namely MG-63,A549 and HT-29, revealed an important enhancement of the effectiveness as compared with both theligand and the free metal ion. Moreover, its cytotoxic effect was remarkably stronger than that of thereference metallodrug cisplatin in all cancer cell lines tested, a promissory result in the search fornew metallodrugs of essential transition metals.