Facing facts: Coordination of Cp*Ru (Cp*=C(5)Me(5)) to the concave and convex π surfaces of subphthalocyanines constitutes a new approach to the functionalization of subazaporphyrins. While the convex face shows higher reactivity, coordination to the concave side produces a stronger diatropic influence on the Cp* ligand and a greater perturbation of the macrocyclic π-electronic features.

The efficiency of the vinylene moiety as a linker to intercommunicate the subporphyrazine (SubPz) core with other chromophores and redox active systems has been examined. In addition, different substitution patterns for hexaarylated SubPzs have been explored in order to control the absorption, fluorescence, and redox properties independently of one another. Besides X-ray crystallography, complete spectroscopic and electrochemical characterizations have been performed, and the conclusions have been supported by density functional theory calculations. The absorption and emission profiles, as well as the organization of the macrocycles in the crystalline state, are strongly determined by the substitution pattern. Within the hexaarylated family, para-substitution with electron-rich moieties (i.e., phenylene or ether) red-shifts both the SubPz absorption and emission bands. Progressive fading of these effects upon extending the oligophenylene branches from one to three units evidences the less efficient electronic delocalization over the phenyl ends as the oligophenylene branch is enlarged. Contrasting, meta-substitution produces little variation or blue shift of the SubPz Q-band, while bathochromic shifts are always observed for the emission bands. In hexavinylene-SubPzs, peripheral vinylene moieties adopt a coplanar configuration with the aromatic SubPz core, resulting in a π-extended chromophore that preserves the unique electronic tunability of SubPzs. This is reflected by the strong alteration of the SubPz electronic properties produced by phenyl and biphenyl moieties attached to the vinylene ends.

Thirty π-electron-expanded hemiporphyrazines 1a-c have been prepared by crossover condensation reaction of 2,5-diamino-1,3,4-thiadiazole and the corresponding phthalonitrile (3) or diiminoisoindoline (4) derivatives. The expanded azaporphyrin hexamers have been unequivocally characterized by means of spectroscopic, crystallographic, and electrochemical techniques. Weak intramolecular hydrogen bonding imposes a planar conformation to macrocycles. However, the overall electronic delocalization is low, and the nature of the resulting [30]heteroannulene is nonaromatic, as confirmed by NMR studies, XR diffraction analysis, and calculation of the NICS(0) value. Studies on a wide range of physicochemical features including ground, excited, reduced, and oxidized states provide evidence for the wide applicability of these 30 π-electron-expanded hemiporphyrazines in processes involving electron transfer. A key asset of our work is the systematic development of spectroscopic and kinetic markers for the formation and decay of all of the aforementioned species. Thirty π-electron-expanded hemiporphyrazines evolve as broadly absorbing light harvesters with excited state energies of around 2.3 eV that are susceptible to facile one-electron reduction and one-electron oxidation reactions.