Structure, Antimicrobial Activity, Hirshfeld Analysis, and Docking Studies of Three Silver(I) Complexes-Based Pyridine Ligands

Saied M. Soliman,Jörg H. Albering,Ahmed M. A. Badr,Zaheer Ul-Haq,Mona M. Sharaf,Assem Barakat

doi:10.3390/app10144853

Abstract

Three broad spectrum Ag(I) complexes against MDR (multi drug resistance) and ATCC standard bacteria as well as the fungus C. albicans were presented. The three well-known structurally-related Ag(I) complexes, [Ag(pyridine-3-carboxaldhyde)2NO3], 1, [Ag3(2-pyridone)3(NO3)3]n, 2, and [Ag(3-hydroxypyridine)2]NO3, 3, were prepared by the direct combination of AgNO3 with the corresponding pyridine ligands in a water-ethanol mixture. 1 and 3 are molecular compounds while, 2 is a 2D coordination polymer with sheets bridged by strong homoleptic R2,2(8) hydrogen bonds between ligands giving the ins topology. Different contacts affecting the molecular packing in their crystal structures were computed by employing Hirshfeld analysis. Charge transferences from the ligand groups to Ag(I) were analyzed using natural population analysis. The effect of protonation and metal coordination on the tautomerism of 2-pyridone was analyzed using data from the Cambridge Structure Database (CSD). It was found that Lewis acid attachment to both N and O sites favor a state in between the two formal tautomers. All compounds were significantly more active than 17 tested commercial antibiotics against three clinically isolated strains of Ps. Aeruginosa, with 2 and 3 performing best on average against all ten tested bacterial strains but with 3 containing less Ag per weight. Finally, docking studies were carried out to unravel the inhibition mechanism of the synthesized silver(I) complexes.

Highlights

Silver-containing compounds continue to attract academic attention for their antimicrobial properties [1,2,3,4,5,6,7,8] and for the immense variety of its coordination polymers, [9] and sometimes the two coincide [10]
The attractiveness lies in the low human toxicity of silver and silver ions, combined with the in-vitro antimicrobial properties that are on par, or better than conventional antibiotics
In this paper we introduced another group of silver(I) pyridine complexes with relatively high biological activity against a broad spectrum of MDR and ATCC standard bacteria as well as the fungus C. albicans

Summary

Introduction

Silver-containing compounds continue to attract academic attention for their antimicrobial properties [1,2,3,4,5,6,7,8] and for the immense variety of its coordination polymers, [9] and sometimes the two coincide [10]. The attractiveness lies in the low human toxicity of silver and silver ions, combined with the in-vitro antimicrobial properties that are on par, or better than conventional antibiotics. The difficulties lie in the yet sketchy knowledge of the mode(s) of action, [12] the variability of the Ag(I) coordination

Methods

Discussion

Conclusion