Absorption, magnetic circular dichroism, IR spectra, electrochemistry, and molecular orbital calculations of monoaza- and opposite diazaporphyrins

作者：Ogata H; Fukuda T; Nakai K; Fujimura Y; Neya S; Stuzhin PA; Kobayashi N^*

来源：European Journal of Inorganic Chemistry, 2004, (8): 1621-1629.

DOI：10.1002/ejic.200300825

• cyclic voltammetry
• density functional calculations
• magnetic circular dichroism
• porphyrinoids
• UV
• vis spectroscopy

Electronic absorption, magnetic circular dichroism (MCD), IR spectra, and cyclic and differential pulse voltammograms of metal-free and copper monoaza- and opposite diazaporphyr-ins are reported, together with molecular orbital (MO) calculations using the density functional theory (DFT) method. Introduction of nitrogen atoms at the meso position of porphyr-ins caused a blue-shift of the B band and a red-shift of the Q band, with a concomitant decrease and increase of the apparent absorption coefficient, respectively. On going from monoaza to diaza species, the apparent bandwidth at half-height of the B band and the splitting of the Q band do not change significantly for metal-free species, but increase for the copper species. The MCD peaks and troughs correspond closely to the peaks of the absorption spectra, so that these are interpreted as the superimposition of Faraday B terms. The MCD sign pattern (minus-to-plus on going from longer to shorter wavelengths) substantiates experimentally that the splitting between the HOMO and HOMO-1 orbital is larger than that between the LUMO and LUMO+1. Of the copper complexes of octaethylporphyrin (OEP), monoaza- (MAP), diaza- (DAP) and tetraazaporphyrins (TAP), CuTAP is the easiest to reduce and hardest to oxidize. The potential differences between the first oxidation and reduction couples were about 2.1-2.4 V. MO calculations using DFT succeeded in reproducing some of the above spectroscopic and electro-chemical characteristics. In addition, some of the IR bands were assigned on the basis of the DFT calculations.

• 出版日期2004-4-19