Control of absorption properties of tetraazaporphyrin group 15 complexes by modification of their axial ligands.

Tetraazaporphyrin (TAP) complexes with group 15 elements (phosphorus(v) or arsenic(v)) containing two axial OH ligands showed reversible spectroscopic changes with acid or base doping. Spectroscopic and theoretical analysis revealed that the modification of axial ligands can tune the interaction between peripheral substituents and the TAP macrocycle.

Phosphorus(V)-corrole: synthesis, spectroscopic properties, theoretical calculations, and potential utility for in vivo applications in living cells.

The synthesis and properties of phosphorus(V) 5,10,15-tris(4-methoxycarbonylphenyl)corrole (1) have been investigated, and its potential utility for bioimaging applications in living cells has been explored. As would normally be anticipated for corrole complexes, the intensity of the Q(0,0) bands of 1 is greater than those of comparable phosphorus(V) tetraphenylporphyrins, but the ΦF values (0.25 for 1) are found to be comparable. A detailed analysis of the electronic structure of the complex was carried out by comparing electronic absorption and MCD spectral data to the results of TD-DFT calculations. The meso-aryl substituents, which enhance the lipophilicity of 1 and hence result in its localization in intracellular membranes during HeLa cell experiments, are predicted to result in a narrowing of the HOMO-LUMO gap and hence a red shift of the Q(0,0) bands toward the optical window in biological tissues.

Synthesis and properties of fused-ring-expanded porphyrins that were core-modified with Group 16 heteroatoms.

The synthesis of a series of novel core-modified and fused-ring-expanded tetraphenylporphyrins is reported. Theoretical calculations and magnetic circular dichroism (MCD) and fluorescence spectroscopic measurements were used to analyze the effect of core modification with Group 16 oxygen, sulfur, selenium, and tellurium atoms on the optical properties and electronic structures of the porphyrins. Marked redshifts of the Q and B bands and accelerated intersystem-crossing rates were observed, thus making these compounds potentially suitable for use in a variety of applications. The scope for further fine-tuning of these optical properties based on additional structural modifications, such as the incorporation of fused benzene rings to form ABAB structures by using a thiophene precursor with a fused bicyclo[2.2.2]octadiene ring and the introduction of various substituents onto the meso-phenyl rings, is also examined.

Superazaporphyrins: meso-pentaazapentaphyrins and one of their low-symmetry derivatives.

Supersized: Three pentaazapentaphyrin derivatives, that is, the superazaporphyrins (SAzPs), as well as a superphthalocyanine (SPc) and a mixed low-symmetry derivative have been prepared and characterized. Decaaryl SAzPs have a distorted (4n+2) π structure and show the Q bands at about λ=840-880 nm. These compounds are relatively air stable.