Synthesis, crystal structures and anticancer activities of Cu(II), Zn(II) and Cd(II) complexes containing bis(2-pyridyl)-di(4-methoxyphenyl)ethene

Abstract

Three new complexes of Cu(II), Zn(II) and Cd(II) with bis(2-pyridyl)-di(4-methoxyphenyl)ethene (KT1), bis(µ₂-chloro)-dichloro-bis(2-(2,2-di(4-methoxyphenyl)-1-(pyridin-2-yl)vinyl)pyridine)-di-copper(II) (CuKT1), dichloro-2-(2,2-di(4-methoxyphenyl)-1-(pyridin-2-yl)vinyl)pyridine-zinc(II) (ZnKT1) and hexakis(µ₂-chloro)-dichloro-tetrakis(2-(2,2-di(4-methoxyphenyl)-1-(pyridin-2-yl)vinyl)pyridine)-tetra-cadmium(II) (CdKT1) were synthesized and characterized by IR spectroscopy, ¹H NMR spectroscopy and single-crystal X-ray diffraction. The results reveal that ZnKT1 is a mononuclear complex, while CuKT1 and CdKT1 are binuclear and tetranuclear complexes, respectively. The central metal ions are surrounded by two N atoms of bis(2-pyridyl)-di(4-methoxyphenyl)ethene and Cl⁻ ions including pendant and bridged ones. In the ZnKT1 complex, a distorted tetrahedral geometry is formed with Zn(II) as central ion and two chloride ions plus two nitrogen atoms of KT1 as surrounding atoms. CuKT1 is a binuclear complex with two square pyramids formed around the two Cu(II) ions. CdKT1 is a tetranuclear complex with two Cd(II) cations having coordination number six (distorted octahedral geometry) and the other two having coordination number five (distorted trigonal-bipyramidal geometry). The anticancer activity tests on four cancer cell lines, including KB, Hep-G2, Lu and MCF-7, show that ZnKT1 and CuKT1 are active against Hep-G2 and Lu but do not considerably damage KB and MCF-G7. CuKT1 has a considerable effect on two cancer cell lines, Hep-G2 and Lu, with IC₅₀ values of 16(2) and 13(1) μM, respectively. CdKT1 exhibits excellent activity against all four cancer cell lines, with IC₅₀ values ranging from 3.5(2) to 8.8(5) μM, which are lower than those of cisplatin. These complexes exhibit low cytotoxic activity on the normal cell line HEK-293A with IC₅₀ values ranging from 10(1) to 74(5) µM.

Graphical Abstract

Keywords:

• Bis(2-pyridyl)-diarylethene
• mononuclear complex
• binuclear complex
• tetranuclear complex
• crystal structure
• anticancer activity

Disclosure statement

The authors declare that there is no conflict of interest regarding the publication of this paper.

Data availability statement

Spectra obtained from spectroscopic techniques for structure characterization are provided (Figures S1–S8) as well as additional figures illustrating the crystallographic structure determinations (Figures S9–S11). The crystallographic data of ZnKT1, CuKT1 and CdKT1 were deposited at the Cambridge Crystallographic Data Center and can be provided on request using the access codes CCDC 2118314-2118316, via http://www.ccdc.cam.ac.uk/data_request/cif, or from the Cambridge Crystallographic Data Center, 12 Union Road, Cambridge CB2 1EZ, UK by Fax: [phone] or E-mail: [email protected].

Additional information

Funding

This work was supported by the Vietnam National Foundation for Science and Technology Development (NAFOSTED) under Grant number 104.01-2017.344.