Templating Porphyrin Anisotropy via Magnetically Aligned Carbon Nanotubes

The preparation and characterisation of a novel three-dimensional organic material consisting of porphyrin arrays on carbon nanotubes embedded in an organogel is reported. Firstly, the porphyrin array was prepared through metal-ligand coordination of a ditopic ligand (1,2-bis(4-pyridyl)ethane) and two bis-Zn(II) porphyrins, linked through a pyrene core, and was studied through UV-Vis, NMR and diffusion spectroscopies. Secondly, the porphyrin supramolecular architecture was adsorbed on pristine carbon nanotubes, greatly improving the dispersibility of the latter in organic solvents. The hybrid material was characterised by means of UV-Vis spectroscopy, microscopic techniques and thermogravimetric analysis. Finally, by exploiting the anisotropic magnetic susceptibility of carbon nanotubes, the hybrid material was aligned under a magnetic field, the organisation of which could be maintained by in situ gelation. The resultant hybrid organogel exhibited notable optical anisotropy, suggesting an anisotropic arrangement of the porphyrin-CNTs architectures in the macroscopic material.