Self-Assembly and Host−Guest Interaction of Metallomacrocycles Using Fluorescent Dipyrazole Linker with Dimetallic Clips

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 1·4PF6¯ (1 = {[(bpy)Pd]4L12}4+), 3·4PF6¯·8CH3CN·H2O (3 = {[(bpy)Pd]4L22}4+), and 7·4PF6¯·6H2O (7 = {[(bpy)Pd]4L52}4+). The 1:1 host−guest complexation for anthracene-based dipyrazolate-bridged macrocycles with aromatic guests was investigated via UV−vis and fluorescent titration.

本研究以配位双核金属夹子[(bpy)₂Pd₂(NO₃)₂](NO₃)₂或[(phen)₂Pd₂(NO₃)₂](NO₃)₂（其中bpy为2,2'-联吡啶，phen为1,10-菲咯啉）作为转角单元，以蒽基、萘基及苯基为骨架的二吡唑二阴离子作为连接臂，通过水溶液中的定向自组装方法合成了一系列带正电的金属大环([M₄L₂]⁴+或[M₈L₄]⁸+)。每个金属大环均带有可结合溶剂分子或阴离子的空腔。针对化合物1·4PF₆⁻（1 = {[(bpy)Pd]₄L1₂}⁴+）、3·4PF₆⁻·8CH₃CN·H₂O（3 = {[(bpy)Pd]₄L2₂}⁴+）以及7·4PF₆⁻·6H₂O（7 = {[(bpy)Pd]₄L5₂}⁴+），通过元素分析、¹H与¹³C核磁共振波谱、电喷雾电离质谱以及单晶X射线衍射分析对其结构进行了表征。通过紫外-可见吸收光谱与荧光滴定实验，研究了基于蒽基二吡唑桥连的金属大环与芳香客体的1:1主客体络合作用。