| Abstract
| - A one-dimensional halogen-bridged complex of platinum [Pt(en)2][PtCl2(en)2] was dispersed in organic media via formation of a lipophilic polyion complex with anionic amphiphiles. Charge-transfer absorption bands of halogen-bridged complexes are maintained in organic media, with varied colors depending on the chemcial structure of constituent amphiphiles. The complex solubilized in chloroform undergoes reversible dissociation and reassembly processes, giving rise to a self-assembling molecular wire in solution.
- A novel class of supramolecular assemblies in organic media consisting of a molecular wire of a halogen-bridgedplatinum complex [Pt(en)2][PtCl2(en)2]4+ (en = 1,2 -diaminoethane) and anionic amphiphiles is developed. Whendouble-chained phosphates or sulfonates are employed, the resultant [Pt(en)2][PtCl2(en)2]4+−lipid complexesdisplayed intervalence charge transfer (CT) absorption bands in the crystalline state. They are soluble in organicsolvents because of the amphiphilic superstructure, in which the solvophobic one-dimensional platinum complexis surrounded by solvophilic alkyl chains. CT absorption bands of halogen-bridged linear complexes are maintainedin organic media, with varied colors that depend on the chemical structure of constituent amphiphiles. Monoalkylatedphosphates failed to form colored, halogen-bridged ternary complexes probably because of their coordination tothe axial position of PtII(en)2. Formation of mesoscopic supramolecular assemblies in organic media was confirmedfor the [Pt(en)2][PtCl2(en)2] complexes by electron microscopy. Interestingly, a supramolecular complex consistingof dihexadecyl sulfosuccinate and [Pt(en)2][PtCl2(en)2]4+ displayed clear, indigo solutions that are distinct fromthe yellow color observed for those of [Pt(en)2][PtCl2(en)2]/dialkyl phosphate complexes. The indigo color of theformer complex disappeared upon heating the solution to 60 °C, whereas it reappeared reversibly by cooling thesolution to room temperature. In electron microscopy, rodlike nanostructures with a minimum width of 18 nmand lengths of 700−1700 nm were observed after cooling, though not at elevated temperatures. Apparently, thelipid−[Pt(en)2][PtCl2(en)2]4+ complex undergoes reversible dissociation and reassembly processes in chloroform,and it becomes better dispersed after the reassembling process. The present finding opens a general route tosolution chemistry of low-dimensional inorganic complexes and enables rational design and control of self-assembling inorganic molecular wires.
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