Design, Synthesis, and Antibacterial Assessment of Silver(I)-Based Coordination Polymers with Variable Counterions and Unprecedented Structures by the Tuning Spacer Length and Binding Mode of Flexible Bis(imidazole-2-thiones) Ligands

• Published in: Crystal growth & design Vol. 17; no. 10; pp. 5249 - 5262
• Main Authors: Beheshti, Azizolla, Soleymani-Babadi, Susan, Mayer, Peter, Abrahams, Carmel T, Motamedi, Hossein, Trzybiński, Damian, Wozniak, Krzysztof
• Format: Journal Article
• Language: English
• Published: American Chemical Society 04-10-2017
• ISSN: 1528-7483; 1528-7505
• DOI: 10.1021/acs.cgd.7b00784

An investigation of the impact of alkyl spacer length of the flexible ligands and influence of shape and coordination ability of the counterions has been done on a series of five silver­(I)-bis­(imidazole-2-thione) coordination polymers. The five compounds, namely, [Ag2 L 4 (NO3)2] n , {[AgL 4 ]2[CF3SO3]2} n , [Ag2 L 6 (CF3SO3)2] n , [Ag2 L 6 (NO3)­(ClO4)] n , and [Ag2 L 6 Br2] n (L 4 = 1,1′-(butane-1,4-diyl)­bis­(3-methylimidazoline-2-thione) and L 6 = 1,1′-(hexane-1,4-diyl)­bis­(3-methylimidazoline-2-thione) have been characterized by elemental analysis, IR spectra, thermogravimetric analysis (TGA), powder X-ray diffraction, and single crystal X-ray diffraction. In the title polymers, the L 4 and L 6 ligands exhibit unprecedented coordination modes, and the Ag­(I) centers adopt a range of coordination geometries. The single crystal structural analysis of the title compounds shows that polymers based on the L 4 ligand predominately adopt AgS4 core structure which does not appear in the polymers containing L 6 ligand. The TGA experimental data reveal that these compounds start to decompose in the temperature range of 240–341 °C. All of the synthesized compounds, in particular, polymer 2, possess antibacterial activity against the selected strain of Gram-negative (Escherichia coli, Pseudomonas aeruginosa) and Gram-positive (Staphylococcus aureus, Bacillus subtilis) bacteria.