Investigations of Bis(alkylthiocarbamato)copper Linkage Isomers.

Linkage isomers are coordination compounds with the same composition but different donor atoms, resulting in distinct physical and electronic structures. A pair of linkage isomers, CuL555 and CuL465, derived from phenylglyoxal bis(ethylthiocarbamate) were synthesized, isolated, and characterized by structural, electrochemical, and spectroscopic methods. The isomers are stable in solution under ambient conditions, but CuL465 converts to CuL555 in acid, consistent with quantum-chemical calculations. The complexes were screened against a lung adenocarcinoma cell line (A549) and a nonmalignant lung fibroblast cell line (IMR-90) to evaluate the antiproliferation activity. CuL555 and CuL465 possessed EC50 values of 0.113 ± 0.030 and 0.115 ± 0.038 μM for A549 and 1.87 ± 0.29 and 0.77 ± 0.22 μM for IMR-90, respectively.