ABSORPTION, FLUORESCENCE, AND MAGNETIC CIRCULAR-DICHROISM SPECTRA OF AND MOLECULAR-ORBITAL CALCULATIONS ON TETRABENZOTRIAZAPORPHYRINS AND TETRANAPHTHOTRIAZAPORPHYRINS

Extensive analyses of the electronic absorption, magnetic circular dic hroism (MCD),;nd fluorescence emission and excitation spectra of perip herally-substituted tetrabenzotriazaporphyrin (TBTrAP) and tetranaphth otriazaporphyrin (TNTrAP) complexes are reported. ZINDO calculations o f the UV-visible absorption spectra of free base and dianionic (deprot onated) TBTrAP and TNTrAP complexes are described. The optical spectra of TBTrAP and TNTrAP are assigned on the basis of molecular orbital ( MO) calculations using the ZINDO program and the theory that has been developed previously to account for the spectral properties of porphyr in and phthalocyanine complexes. Analysis of the absorption and MCD sp ectra of the ring-reduced anion radical species of Pc and TBTrAP compl exes shows that the optical spectra of [TBTrAP(-3)](-) are markedly di fferent from those oi analogous Pc species. EPR signals observed at 77 It for Pc(-3) radical species provide evidence for a doublet ground s tate, while the absence of an EPR signal for [TBTrAP(-3)](-) indicates that the species dimerizes upon reduction. The absorption and MCD spe ctra of the dimeric [TBTrAP(-3)](-) species are found to be consistent with the band assignment developed previously to account for the spec tral properties of main group Pc anion radicals.