•Environments of ReI(CO)3(phen) are a result of poly(4-vinylpyridine) morphology.•Morphology is dependent on pyridine protonation and polymer concentration.•Morphological changes strongly influence the pendent ReI photophysics.•An 8-fold increase in the luminescence quantum yield after protonation.•A large increase of the luminescence lifetime with polymer concentration.Photochemical and photophysical properties of a polymer, Re-P4VP, consisting of Re(I)(CO)3(phen) pendants grafted to a poly-4-vinylpyridine backbone, P4VP, were interpreted on the bases of morphological transformations. These transformations are responsible of a significant increase of the MLCTRe(I)→phen excited state luminescence lifetime when the polymer concentration is increased. Also a nearly 8-fold increase in the luminescence quantum yield resulted from the protonation of Re-P4VP with consequent changes of the excited state decay kinetics. Results of TEM and AFM morphological studies on P4VP and Re-P4VP in the presence of HClO4 acid, i.e., to form Re-P4VPHnn+, revealed that they have concentration dependent morphologies. From low to large concentrations of the Re-P4VP polymer, the morphology of Re-P4VP varies from a nonhomogeneous distribution of spherical nanoaggregates coexisting with micrometer size fibers to an homogeneous distribution of spherical nanoaggregates with diameters around 25 nm. The Re-P4VP morphology is also altered when the polymer pyridines are protonated. Protonation of diluted solutions of Re-P4VP polymers decrease the sizes of the nanoaggregates and small objects with diameters smaller than 10 nm appear.

The X-ray characterization of the five-coordinate picket-fence porphyrin complex, [Co(TpivPP)(2-MeHIm)], is reported. The complex has the displacement of cobalt from the porphyrin plane = 0.15 Å, and Co−NIm = 2.145(3) and (Co−Np)av = 1.979(3) Å. This five-coordinate complex, in the presence of dioxygen and excess 2-methylimidazole, undergoes an unanticipated, photoinitiated atropisomerization of the porphyrin ligand, oxidation of cobalt(II), and the formation of the neutral cobalt(III) complex [Co(α,α,β,β-TpivPP)(2-MeHIm)(2-MeIm−]. Two distinct examples of this complex have been structurally characterized, and both have structural parameters consistent with cobalt(III). The two new Co(III) porphyrin complexes have axial Co−NIm distances ranging from 1.952 to 1.972 Å, but which allow for the distinction between imidazole and imidazolate. An interesting intermolecular hydrogen bonding network is observed that leads to infinite helical chains. UV−vis spectroscopic study suggests that [Co(TpivPP)(2-MeHIm)(O2)] is an intermediate state for the oxidation reaction and that the atropisomerization process is photocatalyzed. A reaction route is proposed based on the spectroscopic studies.