One-pot crystallization of two 1,4-cyclohexanedicarboxylate-based tetranuclear Cu(ii) compounds and their DNA binding affinities

Abstract

Two new tetranuclear compounds [Cu₄(cis-1,4-chdc)₂(2,2′-bpy)₄(H₂O)₄]·4(ClO₄) (1) and [Cu₄(cis-1,4-chdc)₂(2,2′-bpy)₄(μ₂-OH)₂]·2ClO₄·2H₂O (2) [1,4-H₂chdc = 1,4-cyclohexanedicarboxylic acid, 2,2′-bpy = 2,2′-bipyridine] have been prepared by stirring copper(II) perchlorate hexahydrate [Cu(ClO₄)₂·6H₂O] with 2,2′-bpy and the sodium-salt of 1,4-H₂chdc. The compounds are formed in a one-pot crystallization and are visibly distinct in colour with dark blue and sky blue appearances, respectively, for 1 and 2. Both compounds have been characterized by elemental analysis as well as single crystal X-ray diffraction (SCXRD) techniques. Interestingly, both the compounds show significant DNA binding affinity with ctDNA and these experimental findings are further corroborated by a docking study. However, compound 1 with a higher cationic charge exhibits a better DNA binding affinity compared to 2.