Copper(II) and manganese(II) picrate complexes with the V-shaped ligand 1,3-bis(1-methylbenzimidazol-2-yl)-2-thiapropane: preparation, structure, DNA-binding properties and antioxidant activities

Cu(I) complexes regulated by N-heterocyclic ligands: Syntheses, structures, fluorescence and electrochemical properties

Three mononuclear Cu(I) complexes, namely, [Cu(2-PBO)(PPh₃)₂]·ClO₄·2CH₂Cl₂ (1), [Cu(3-PBO)(PPh₃)₂(ClO₄)]·CH₂Cl₂ (2) and [Cu(PBM)(PPh₃)₂]·ClO₄ (3) (2-PBO = 2-(2'-Pyridyl)benzoxazole, 3-PBO = 2-(3'-Pyridyl)benzoxazole, PBM = 2-(2'-Pyridyl)benzimidazole, PPh₃ = triphenylphosphine) have been synthesized and characterized by elemental analyses, IR, ¹H NMR, ¹³C NMR, X-ray single crystal diffraction and thermal analysis. Photoluminescent investigation shows that complexes 1-3 exhibit distinct tunable light green (512 nm)-to-yellow (557 nm) photoluminescence by varying the N-heterocyclic ligands. Three complexes show intense 2-PBO-based yellow, 3-PBO-based light green and intense PBM-based bright green luminescence upon irradiation with a standard UV lamp (λ_ex = 254 nm) at room temperature. Moreover, the electrochemical properties of 1-3 have been investigated by cyclic voltammetry. The results suggest the frontier molecular orbits and the HOMO-LUMO energy gaps of these cuprous complexes are effectively adjusted through the introduction of different N-heterocyclic ligands, thus achieving the selective luminescence of the cuprous complexes.