Details

Autor(en) / Beteiligte

• Nemykin, Victor N.
• Makarova, Elena A.
• Grosland, Jeffrey O.
• Dudkin, Semyon V.
• Dennison, Richard
• Purchel, Anatolii A.

Titel

Tuning the near-IR band energy and redox potentials of magnesium tetra(ferrocenyl)tetraazaporphyrins

Ist Teil von

• Journal of porphyrins and phthalocyanines, 2014-08, Vol.18 (8n09), p.792-803

Ort / Verlag

Singapore: World Scientific Publishing Company

Erscheinungsjahr

2014

Beschreibungen/Notizen

• Magnesium 2(3),7(8),12(13),17(18)-tetraferrocenyl-5,10,15,20-tetraazaporphyrin (3), and magnesium 2(3),7(8),12(13),17(18)-tetracyano-3(2),8(7),13(12),18(17)-tetraferrocenyl-5,10,15,20-tetraazaporphyrin (4) complexes were prepared using template condensation reaction between magnesium butoxide and (Z)-dicyanovinylferrocene (1) and tricyanovinylferrocene (2), respectively. Redox and unusual optical properties of macrocyclic compounds 3 and 4 were investigated in details using UV-vis, MCD, electro-, and spectroelectrochemical methods as well as DFT and TDDFT calculations. It was shown that the HOMO in both compounds resembles Goutermans' a1u orbital (D4h symmetry), which is different from meso-ferrocenyl containing porphyrins. In both macrocycles 3 and 4 overlapping oxidation waves for ferrocene substituents were observed in electrochemical and spectroelectrochemical experiments. Electrochemically observed oxidation waves are rather broad because of the presence of positional isomers and span only ~300 mV range in DCM/0.05 M TBAF system. Based on the excellent agreement between experimental UV-vis spectra and TDDFT predicted excitation energies, it was suggested that the low-energy NIR and visible regions are predominantly composed by the MLCT transitions with a significant π–π* mixing. Two ferrocene-substituted magnesium tetraazaporphyrins with direct ferrocene-tetraazaporphyrin bond were prepared and characterized using UV-vis, MCD, NMR, and mass spectrometries. Redox and unusual optical properties of new compounds were investigated using UV-vis, MCD, electro-, and spectroelectrochemical methods and correlated with DFT and TDDFT calculations.