Synthesis, Characterization, and Anti-<i>TB</i> Application of Redox-Active Ethyl Carbazate-Derivatized Phenanthroline and Its Silver Complexes
Ravallika Aluri, Aishwarya Natarajan, Jyothi Kumari, Dharmarajan Sriram, Pralok K. Samanta, Aditi Gangopadhyay, Krishnan Rangan
Abstract
High Resolution Image Download MS PowerPoint Slide Exploring the design and synthesis of new antibiotic compounds is important to treat multidrug-resistant bacterial infections for the already exposed drug molecules. In this work, a phenanthroline derivative, namely, 6-[2-(ethoxycarbonyl)diazen-1-yl]-1,10-phenanthroline-5-one (ECDPO), and its mono- and bis-ligand silver complexes [Ag(ECDPO)(NO 3 )] and [Ag(ECDPO) 2 ](NO 3 ) were synthesized. Single-crystal X-ray diffraction (XRD) structure of methanol-solvated ECDPO was studied, which crystallized in a monoclinic system, P 2 1 / n space group. ECDPO is a planar molecule, and supramolecular arrays are stabilized by various hydrogen bonding, namely, O–H···N, N–H···O, and C–H···O, and π–π interactions. The spectroscopic features of ECDPO and its silver complexes were thoroughly studied by high-resolution mass spectrometry (HRMS), IR, 1 H NMR, 13 C NMR, UV–visible spectroscopy, and X-ray photoelectron spectroscopy (XPS). Electrochemical redox features were studied by cyclic voltammetry. The ECDPO molecule and its silver complexes were studied for antibacterial activity against Escherichia coli bacteria and Mycobacterium tuberculosis ( Mtb ). ECDPO shows a minimum inhibitory concentration (MIC) of 1.56 μg/mL against Mtb, which is comparable to that of one of the clinically used drug candidates, namely, ethambutol. Silver complexes [Ag(ECDPO)(NO 3 )] and [Ag(ECDPO) 2 ](NO 3 ) showed enhanced anti -TB activities and MICs of 0.78 and 0.39 μg/mL, respectively.