Controllable self-assemblies of micro/nano-tubes and vesicles from arylamides and their applications as templates to fabricate Pt micro/nano-tubes and hollow Pt nanospheres

Abstract

A novel class of nonamphiphilic aromatic amides (T1–T3) have been designed and synthesized from naphthalene-2,7-diamine or 2-amino-naphthalene and a 5-hydroxy-isophthalic acid segment, which is revealed to selectively assemble into vesicular or tubular architectures, depending on the solvents and concentrations. T1 and T2 form vesicles in methanol, but can be converted into micro/nano-tubes when water is added and further gelate the binary solvent when the concentration is high enough. In contrast, T3 self-assembles into fine tubular structures in methanol, but can be transformed into vesicles upon being diluted or adding chloroform. The morphology transition has been investigated by SEM, AFM, TEM and fluorescent microscopy, which also reveal that microtubes of large size are formed through the fusion of vesicles of small size, which is driven by the cooperative hydrogen bonding and aromatic stacking interactions, as evidenced by the X-ray investigation on an analogue of T3. The novel organic micro/nano-tubes and vesicles are further used to template the fabrication of Pt micro/nano-tubes or hollow Pt spheres by in situ reduction of the absorbed K₂PtCl₄ with ascorbic acid, as confirmed by SEM, TEM and EDX analyses.