In-situ spectroelectrochemistry (EPR, UV–visible) and aggregation behavior of H2 BDCP and Zn(II)BDCP [BDCP = {5,10,15,20-tetrakis[3,4-(1,4-dioxan)phenyl]porphyrin}2−]

• Spectroelectrochemistry (EPR, UV–visible) of 1 and 2 were performed.
• 2 forms self-assembled systems in DMF-water binary mixtures.
• A mechanism has been also proposed for the generation of different aggregates.

In-situ UV–visible and EPR Spectroelectrochemistry of a free base porphyrin, 5,10,15,20-tetrakis[3,4-(1,4-dioxan)phenyl]porphyrin, and its zinc derivative, 5,10,15,20-tetrakis[3,4-(1,4-dioxan)phenyl]porphyrinatozinc(II) were performed. On one-electron oxidation of the free base porphyrin in dichloromethane/0.1 M BuN4PF6 using an optically transparent thin layer cell, the initial Soret band retains its intensity and an equally intense new band appears at 453 nm. The initial Q bands disappear, and new bands appear at 516, 555 and 694 nm. At 295 K, it exhibits an isotropic EPR signal with a peak to peak separation of about 6 G and centered at g = 2.004. On one-electron oxidation of the zinc-porphyrin in similar conditions, the Soret band loses its intensity, and a new band appears at 466 nm. The in-situ generated one-electron oxidized species exhibits an isotropic EPR signal at 295 K which is centered at g = 2.0035. The formations of aggregates/self-assemblies of zinc-porphyrin were monitored by UV–vis spectroscopy, fluorescence imaging by confocal microscope, TEM, SEM and DLS measurements. A tentative mechanism has been also proposed for the generation of different aggregates, with varying size and shape, in water–DMF binary mixtures.

In-situ UV–visible and EPR Spectroelectrochemistry of a free base porphyrin, and its zinc derivative are reported. Spectroscopic evidences have been gathered to elucidate the electronic structures of the porphyrin and zinc-porphyrin cation radicals. The formations of self-assemblies are demonstrated by UV–vis spectroscopy, TEM, SEM, and DLS measurements.Figure optionsDownload as PowerPoint slide