Density functional theory study of electronic absorption spectra and intermolecular interactions of porphyrin–borate complexes

Porphyrin Diacid-Polyelectrolyte Assemblies: Effective Photocatalysts in Solution

Developing effective and versatile photocatalytic systems is of great potential in solar energy conversion. Here we investigate the formation of supramolecular catalysts by electrostatic self-assembly in aqueous solution: Combining positively charged porphyrins with negatively charged polyelectrolytes leads to nanoscale assemblies where, next to electrostatic interactions, π⁻π interactions also play an important role. Porphyrin diacid-polyelectrolyte assemblies exhibit a substantially enhanced catalytic activity for the light-driven oxidation of iodide. Aggregates with the hexavalent cationic porphyrin diacids show up to 22 times higher catalytic activity than the corresponding aggregates under neutral conditions. The catalytic activity can be increased by increasing the valency of the porphyrin and by choice of the loading ratio. The structural investigation of the supramolecular catalysts took place via atomic force microscopy and small angle neutron scattering. Hence, a new facile concept for the design of efficient and tunable self-assembled photocatalysts is presented.

One-dimensional porphyrin nanoassemblies assisted via graphene oxide: sheetlike functional surfactant and enhanced photocatalytic behaviors

Surfactant-assisted self-assembly (SAS) has received much attention for supramolecular nanoassemblies, due to its simplicity and easiness in realizing a controllable assembly. However, in most of the existing SAS protocols, the employed surfactants work only as a regulator for a controllable assembly but not as active species for function improvement. In this paper, we report that a porphyrin, zinc 5,10,15,20-tetra(4-pyridyl)-21H,23H-porphine (ZnTPyP), could be assembled to form one-dimensional (1D) supramolecular nanostructures via a SAS method, wherein graphene oxide (GO) plays a fascinating role of sheetlike surfactant. We show that, when a chloroform or tetrahydrofuran solution of ZnTPyP is injected into an aqueous dispersion of GO, 1D supramolecular nanoassemblies of ZnTPyP with well-defined internal structures could be easily formulated in a controllable manner. Our experimental facts disclose that the complexation of ZnTPyP with the two-dimensional GO nanosheets plays an important role in this new type of SAS. More interestingly, compared with the 1D ZnTPyP nanoassemblies formulated via a conventional SAS, wherein cetyltrimethylammonium bromide is used as surfactant, those constructed via our GO-assisted SAS display distinctly enhanced photocatalytic activity for the photodegradation of rhodamine B under visible-light irradiation. Our new findings suggest that GO could work not only as an emergent sheetlike surfactant for SAS in terms of supramolecular nanoassembly but also as functional components during the performance of the assembled nanostructures.