Self-assembly of metallomacrocycles with dipyrazole ligands and anion sensing of [Pd4Fe2] macrocycle with ferrocene-based dipyrazole ligand

Abstract

By employing dipalladium corners [(bpy)(2)Pd(2)(NO(3))(2)](NO(3))(2) or [(phen)(2)Pd(2)(NO(3))(2)](NO(3))(2) (where bpy = 2,2'-bipyridine and phen = 1,10-phenanthroline) to bridge ferrocene-based dipyrazole ligand (L(1)) and m-phenylene-based dipyrazole ligands (L(2-3)) in aqueous solution, a series of positively-charged [M(4)L(2)](4+) metallomacrocycles were obtained. Their structures were characterized by (1)H NMR, electrospray ionization mass spectrometry (ESI-MS), elemental analysis, and single crystal X-ray diffraction analysis for 1·4NO(3) ({[(bpy)Pd](4)L(1)(2)}(NO(3))(4)) and 4·4NO(3) ({[(phen)Pd](4)L(2)(2)}(NO(3))(4)). In their single crystal structures, NO(3)(-) anions are located at the dipalladium corners by C-H...O hydrogen bonds. Importantly, the anion-sensing properties of ferrocene functionalized [Pd(4)Fe(2)] hetero-metallomacrocycle 1 were investigated in acetonitrile by SWV, CV and NMR analysis, showing promise for Br(-) sensing.