A Pd8 Tetrafacial Molecular Barrel as Carrier for Water Insoluble Fluorophore

A new carbazole-based tetraimidazole ligand 1,3,6,8-tetra­(1H-imidazol-1-yl)-9-methyl-9H-carbazole (L) has been synthesized. The unsymmetrical nature of L as well as the rotational freedom of imidazole donor moieties around C–N bond make it a special building unit, which upon treatment with cis-(tmeda)­Pd­(NO3)2 produced an unprecedented single linkage-isomeric Pd8 tetrafacial molecular nanobarrel (PSMBR-1) [tmeda = N,N,N′,N′-tetramethylethane-1,2-diamine]. Unlike closed architectures, open barrel architecture of water-soluble PSMBR-1 makes it an ideal host for some water insoluble polyaromatic hydrocarbons in aqueous medium; one such inclusion complex coronene⊂PSMBR-1 was characterized by X-ray diffraction study. Moreover, the potential application of PSMBR-1 as carrier in aqueous medium for the transportation of water insoluble fluorophore (perylene) for live cell imaging is explored.

本研究合成了一种基于咔唑的四咪唑配体1,3,6,8-四(1H-咪唑-1-基)-9-甲基-9H-咔唑（记为L）。该配体具有非对称结构，且咪唑供体基团可围绕C-N键自由旋转，使其成为一类特殊的配位构筑单元。将其与cis-(tmeda)Pd(NO3)2（tmeda = N,N,N′,N′-四甲基乙二胺）反应，得到了前所未有的单连接异构Pd8四面体型分子纳米桶（PSMBR-1）。与封闭型配位架构不同，水溶性的PSMBR-1拥有开放的桶状结构，可作为理想的主体分子用于水相体系中包合水不溶性多环芳烃；其中一例包合复合物晕苯⊂PSMBR-1已通过X射线衍射分析完成表征。此外，本研究还探索了PSMBR-1作为载体在水相体系中转运水不溶性荧光染料苝用于活细胞成像的潜在应用价值。