Nano-Supramolecular Assemblies Constructed from Water-Soluble Bis(calix[5]arenes) with Porphyrins and Their Photoinduced Electron Transfer Properties

Possessing 2D netlike and ID linear morphologies, two nano-supramolecular architectures A1 and A2 are constructed by tetracationic porphyrin (G1) and dicationic porphyrin (G2), respectively, upon complexation with the novel water-soluble biso-7sulfonatocalix[5]arenes) bridged at the lower rim (H2). Corresponding to the molecular design, the aggregation morphologies are well manipulated by the inherent binding sites of the building blocks through host-guest interactions as well as charge interactions. In comparison to the simple p-sulfonatocalix[5]arene H1 which can only form particle-type complexes C1 and C2 with porphyrin guests, H2 provides excellent pre-organized structure to construct highly complex nano-supramolecular assemblies. The exhibited electron-transfer process of the supramolecular systems is further investigated by steady-state and time-resolved fluorescence spectroscopy, electrochemical measurements, and transient absorption spectroscopy. The results obtained show that calixarenes are also effective electron donors in PET besides acting as significant building blocks, which gives them many advantages in constructing well-ordered nanomaterials with the capability of electron and energy transport.