Solution self-assembly, spontaneous deprotonation, and crystal structures of bipyrazolate-bridged metallomacrocycles with dimetal centers

Abstract

A series of nanosized cavity-containing bipyrazolate-bridged metallomacrocycles with dimetal centers, namely, {[(bpy)M]8L4}(NO3)8 [L=3,3',5,5'-tetramethyl-4,4'-bipyrazolyl, Pd, Pt; 1,4-bis-4'-(3',5'-dimethyl)-pyrazolylbenzene), Pd; and 1,4-bis-4'-(3',5'-dimethyl)-pyrazolylbiphenyl, Pd], {[(phen)M]8L4}(NO3)8 [L=3,3',5,5'-tetramethyl-4,4'-bipyrazolyl, Pd, Pt; 1,4-bis-4'-(3',5'-dimethyl)-pyrazolylbenzene, Pd; and 1,4-bis-4'-(3',5'-dimethyl)-pyrazolylbiphenyl, Pd], {[(bpy)Pd]6L3}(NO3)6 [L=1,4-bis-4'-(3',5'-dimethyl)-pyrazolylbenzene,], {[(phen)Pd]6L3}(NO3)6 [L=1,4-bis-4'-(3',5'-dimethyl)-pyrazolylbenzene,], {[(bpy)Pd]4L2}(NO3)4 [L=1,3-bis-4'-(3',5'-dimethyl)-pyrazolylbenzene, and 1,2-bis-4'-(3',5'-dimethyl)-pyrazolylbenzene,], and {[(phen)Pd]4L2}(NO3)4 [L=1,3-bis-4'-(3',5'-dimethyl)-pyrazolylbenzene, and 1,2-bis-4'-(3',5'-dimethyl)-pyrazolylbenzene,] (where bpy=2,2'-bipyridine and phen=1,10-phenanthroline) have been synthesized through a directed self-assembly approach that involves spontaneous deprotonation of the 1H-bipyrazolyl ligands in aqueous solution. These complexes, with weak Pd(II)...Pd(II) or Pt(II)...Pt(II) interactions, have been characterized by elemental analysis, 1H and 13C NMR, cold-spray ionization or electrospray ionization mass spectrometry, UV-visible spectroscopy, and luminescence spectroscopy. Complexes and have also been characterized by single-crystal X-ray diffraction analysis.