Synthesis and X-ray crystal structures of three new terpyridine-based Pb(II) complexes, cytotoxicity studies of {[Pb(ttpy)(μ-AcO)]₂}(SCN)₂

Abstract

Synthesis and X-ray crystal structures of three new terpyridine-based Pb(II) complexes, {[Pb(ttpy)(μ-AcO)]₂}(SCN)₂ (1) (ttpy = 4′-tolyl-2,2′:6′,2″-terpyridine), [Pb(Clphtpy)(AcO)(ClO₄)] (2), and [Pb(Clphtpy)(SCN)₂] (3) (Clphtpy = 4′-(4-chlorophenyl)-2,2′:6′,2″-terpyridine), are described. The synthesized materials have been characterized, also, by CHN elemental analysis, ¹H NMR, and IR spectroscopy. The structural analyses showed that, in the solid state, the coordination number of Pb(II) in 1, 2, and 3 are six, seven, and five, respectively. In the complexes, the lone-pair electrons of Pb(II) are stereochemically active and the coordination geometry of Pb(II) is hemidirected. The structures of the three complexes were compared and the effect of counter ion is described. The antibacterial activity of 1 and previously reported {[Pb(ttpy)(μ-AcO)]₂}(PF₆)₂ (1A) and {[Pb(ttpy)(μ-AcO)I]₂} (1B) were tested by minimum inhibitory concentration method to investigate the effect of counter ions on biological activity of the compounds. Also, cytotoxicity test was assessed using 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide assay to determine the maximum non-toxic concentration of ttpy, Pb(II), and their complexes to HepG2 cells. Effective lead detoxification was observed for 1, 1A, and 1B.

Graphical Abstract

Keywords:

• Lead(II) complex
• Terpyridine
• X-ray crystal structure
• Antibacterial activity
• Cytotoxicity
• Lead poison detoxification

Acknowledgements

Support of this investigation by the Payame Noor University, Iran and Atatürk University, Erzurum, Turkey is gratefully acknowledged.