Electronic absorption spectra, macrocyclic complexes

However, in contrast to the human His25Ala HO-l heme complex, which has no detectable activity in the absence of imidazole (78), the His20Ala Hmu O rheme complex in the presence of NAD PH and NADPH-cytochrome P450 reductase was foimd to catalyze the initial meso-hydroxylation of the heme (151). The product of the reaction was Fe verdoheme, as judged by the electronic absorption spectrum and the detection of carbon monoxide as a product of the reaction. Hydrolytic conversion of the verdoheme product to biliverdin and subsequent HPLC analysis confirmed that the oxidative cleavage of the porphyrin macrocycle was specific for the a-meso-carbon. 

The macrocyclic product [Ni(L54)]I is isolated through refluxing an aqueous solution of L52 and nickel(II) acetate with the subsequent addition of an aqueous solution of Nal (Eq. 2,15) [23], The diamagnetism and electronic absorption spectrum of [Ni(L54)]+ indicate that it has a square-planar structure. The peak with the maximal m/z in the mass spectrum of the iodide corresponds to the [Ni(L54)]+ cation. It should be noted that, in the mass spectra of a number of other macro-cyclic coordination compounds of the [ML]X type, the most intense peak in the high-mass number range is [ML]+ as, for example, in case of the nickel( II) complex with the 13-membered macrocycle derived from 3,7-diaza-l,9-diaminononane [24]. 

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