Synthesis, antimicrobial activity and high cell viability of copper derivatives of 2-thiouracil, purine-6-thione and 2,4,6-trimercaptotriazine

Abstract

Reactions of copper(II) acetate with 2-thiouracil (tucH₂) and triphenyl phosphine (1:1:1 or 1:1:2 molar ratios) in methanol-acetonitrile/chloroform mixture yielded a light brown N,S-bridged dinuclear Cu^I complex, [Cu(PPh₃)₂(µ-N,S-tucH)Cu(PPh₃)₂Cl] 1, incorporating uninegative 2-thiouracilate. X-ray crystallography has shown that the crystals of complex 1 comprise a two component twin system and belong to the space group Ia. The major component 1a is about 77% and the minor component 1b is about 23%. One Cu is four-coordinate tetrahedral with center {CuP₂SCl} and the other Cu is three-coordinate distorted trigonal planar with {CuP₂N} center. Crystal data: 1, formula, C₇₆H₆₃ClCu₂N₂OP₄S; space group: Ia; monoclinic, a, 22.2638(9); b, 11.8050(4); c, 27.4455(10) Å; β, 113.358(5); R, 4.80%;173(2) K. The antimicrobial activities of dinuclear 1 as well as that of the previously reported 2-thiouracil, 2,4,6-trimercaptotriazine (tmtH₃) and purine-6-thione (purSH₂) complexes, [CuCl(κ¹-S-tucH₂)(PPh₃)₂] 2, [Cu₂Br₂(μ-S-tucH₂)₂(PPh₃)₂] 3, [Cu(tmtH₂)(PPh₃)₂] 4, [Cu₃Br₂(k¹-N,k¹-S,µ-S-tmtH₂)(PPh₃)₆] 5 and [Cu(k¹-N,k¹-S-purSH)(PPh₃)₂] 6, have been screened against gram negative, Escherichia coli (MTCC 119) and Shigella flexneri (MTCC 1457), gram positive, Enterococcus faecalis (MTCC 439) and Staphylococcus aureus (MTCC 740) microorganism. High percentage of cell viability (96–97%) is observed in some cases.

Graphical Abstract

Keywords:

• 2-Thiouracil
• copper(II)
• 2,4,6-trimercaptotriazine
• purine-6-thione
• triphenyl phosphine

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

Financial assistance from the Council of Scientific and Industrial Research (CSIR), New Delhi for Emeritus Scientist Grant [21(0904)/12-EMR-II] to TSL is gratefully acknowledged. JPJ acknowledges the NSF–MRI program (Grant No. CHE-1039027) for funds to purchase the X-ray diffractometer.