Transition Metal Ion Complexes with Associates of Porphyrin Bound to a Hydrophobic--Hydrophilic Copolymer

A. V. Udal'tsov^*, A. A. Churin, K. N. Timofeev, and Yu. V. Kovalev

School of Biology, Lomonosov Moscow State University, Moscow, 119899 Russia; fax: (095) 939-4658; E-mail: avu@audaltsov.home.bio.msu.ru

^* To whom correspondence should be addressed.

Received October 19, 1998; Revision received January 20, 1999

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The interaction of dimeric forms of meso-tetraphenylporphine with Mn²⁺ as well as the interaction of associated forms of meso-tetra(p-aminophenyl)porphine bound to a hydrophobic--hydrophilic copolymer with Mn²⁺ and Fe³⁺ were studied by absorption, luminescence, Raman, and EPR spectroscopies. Both dimeric and associated forms of these porphyrins produced Mn²⁺ complexes. Manganese ions in these complexes undergo clusterization, which is accompanied by transformation of the six-line EPR signal of Mn²⁺ into a broad single-line signal. The EPR signal of Mn²⁺ in these clusters is characterized by a g-factor value typical of a free electron with half-width DeltaH_pp = 50 mT. The interaction of the two-component complex with Fe³⁺ produces a donor--acceptor complex. The electronic spectrum of the donor--acceptor complex contains a broad band with a maximum at 760 nm. The molar extinction coefficient of the complex at 760 nm is 9.1·10⁴ M^-1·cm^-1, and the rate constant for its formation is K_dac = (3.9 ± 0.6)·10⁶ M^-1. The constants for Mn²⁺ binding to the organic compounds used in this work were also determined.

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KEY WORDS: porphyrin associates, hydrophobic--hydrophilic copolymer, ions of transition metals

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