Mono- and di-ferrocene conjugated 5-methyl benzimidazole based multi-channel receptors for cations/anions with their antimicrobial and anticancer studies

Abstract

Two receptor molecules 1 and 2 (where 1 = 1-(ferrocenylmethyl)-2-ferrocenyl-5-methyl-1H-benzo[d]imidazole and 2 = 2-ferrocenyl-5-methyl-1H-benzo[d]imidazole) having the capability of sensing cations and anions have been synthesized and characterized by FT-IR, NMR (¹H, ¹³C, and DEPT), elemental analysis and ESI Mass spectral analysis. Receptor 1 has been characterized by single-crystal X-ray diffraction studies. The optical and electrochemical studies confirm the multichannel recognition of cations and anions with excellent selectivity and sensitivity towards Sn²⁺ by receptor 1 and Sn²⁺/Cu²⁺ by receptor 2 using acetonitrile solvent. Receptor 2 having an anion binding site shows selective binding towards F⁻ ions via electrostatic attraction. From the UV-visible studies, the binding constant for Sn²⁺ with receptor 2 obtained was K_b = 3.2 × 10³ M⁻¹. The antimicrobial activities of 1 and 2 were studied and the zone of inhibition, MIC, and MBC/MFC results suggest that receptor 1 has more significant activity than 2, with potent antifungal properties. The cytotoxic activity of receptors 1 and 2 was tested with the liver cancer cell line (HepG2) by MTT assay and the IC₅₀ values displayed moderate cytotoxicity for receptors 1 and 2 at 32.27 μM and 41.43 μM, respectively.