Synthesis, study and structural characterization of a new water soluble hexanuclear silver(I) cluster with the 2-mercapto-nicotinic acid with possible antiviral activity

Abstract Silver(I) chloride reacts with 2-mercapto-nicotinic acid (H 2 mna, C 6 H 5 NO 2 S) in the presence of an excess of triethylamine in DMSO to form a hexanuclear, water soluble, cluster of formula {[Ag 6 (μ 3 -Hmna) 4 (μ 3 -mna) 2 ] 2− ·[(Et 3 NH) + ] 2 ·(DMSO) 2 ·(H 2 O)} ( 1 ). The complex 1 was characterized by elemental analyses, and FT-IR, UV–Vis and 1 H NMR spectroscopy. Crystal structures of complex 1 and the ligand, 2-mecapto-nicotinic acid ( 2 ), have been determined by X-ray diffraction. Compound 1 , C 52 H 68 Ag 6 N 8 O 15 S 8 , is monoclinic with a space group P 2 1 / c (No. 14) and a =11.7080(10), b =16.2920(10), c =18.3010(10) A, β =91.350(10)°, Z =4. The entire molecule is ionic and consists of a double anionic hexa-nuclear cluster and two protonated triethylamine counter cations while it is solvated by two DMSO and one water molecule. The 2-mercapto-nicotinic acid ( 2 ), C 6 H 5 NO 2 S, is orthorhombic (space group Pna 2 1 (No. 33), a =8.3910(10), b =13.2720(10), c =5.892 A, Z =4). An extended inter-molecular hydrogen bonding via O⋯HN contacts (O(1)⋯H(5)[N(5)]=1.8998, O(1)⋯N(5)=2.8049 A) links the molecules forming a supramolecular two-dimensional network. Complex 1 , was evaluated for anti-HIV-RT activity. It was found to inhibit the human immunodeficiency viral replication reverse transcriptase (HIV-RT) with calculated inhibiting concentration (IC 50 ) 0.01275±0.00115 mg ml −1 .