Synthesis, Crystal Structure, Luminescence Sensing, and Photocatalytic Properties of a 2D Cobalt(II) Coordination Polymer Containing Bis(benzimidazole) Moieties

Abstract

A new cobalt(II) coordination polymer, namely [Co(L)(Ndc)]_n (I), where L = 1,5-bis(5,6- dimethylbenzimidazole)pentane, H₂Ndc = 2,6-naphthalenedicarboxylic acid, was synthesized and characterized by elemental analysis, IR spectra, powder X-ray diffraction and single-crystal X-ray diffraction (CIF file CCDC no. 1548044). Complex I displays a 2D (4,4) layer which further extended into a 3D supramolecular framework via weak C–H···O hydrogen bondings. The luminescence explorations demonstrated that I exhibits highly selective and sensitive sensing for Cr₂O₇²⁻ with high quenching efficiency K_sv value of 9.87 × 10³ L mol⁻¹ and low detection limit (0.24 μM (S/N = 3)). Meanwhile I also exhibits highly selective and sensitive sensing for Fe³⁺ with quenching efficiency K_sv = 3.6 × 10⁴ L mol^–1 and low detection limit (0.32 μM (S/N = 3)). Complex I exhibits higher photocatalytic activities for the degradation of methylene blue under UV irradiation. Additionally, the thermal behavior and electrochemical properties of the compound are also presented.