Self-assembly and host-guest interaction of metallomacrocycles using fluorescent dipyrazole linker with dimetallic clips

Abstract

By employing diimine ligands coordinated dimetallic clips ([(bpy)2Pd2(NO3)2](NO3)2 or [(phen)2Pd2(NO3)2](NO3)2, where bpy = 2,2′-bipyridine, phen = 1,10-phenanthroline) as the corner and anthracene-, naphthalene-, and benzene-based dipyrazolate dianions as the linker, a series of positively charged metallomacrocycles ([M4L2]4+ or [M8L4]8+) have been synthesized through a directed self-assembly method in aqueous solution. Every macrocycle has a cavity to bind solvent molecules or anions. The structures were characterized by elemental analysis, 1H and 13C NMR, electrospray ionization mass spectrometry, and single crystal X-ray diffraction analysis for compound 1 x 4 PF6(-) (1 = {[(bpy)Pd]4L(1)2}4+), 3 x 4 PF6(-) x 8 CH3CN x H2O (3 = {[(bpy)Pd]4L(2)2}4+), and 7 x 4 PF6(-) x 6 H2O (7 = {[(bpy)Pd]4L(5)2}4+). The 1:1 host-guest complexation for anthracene-based dipyrazolate-bridged macrocycles with aromatic guests was investigated via UV-vis and fluorescent titration.