Resonance Raman spectra of N-deprotonated sigma-type dianion of porphycenes.

Resonance Raman spectra of N-deprotonated sigma-type dianion of porphycenes were measured in an effort to characterize the structural changes concomitant with N-deprotonation. The observed resonance Raman behavior was consistent with the results of vibrational analysis by quantum chemical calculations based on density functional theory methods. Resonance Raman behavior predicted an expanded porphycene core for N-deprotonated sigma-type dianion with elongation of peripheral bond lengths.

Reaction of beta-diketiminate copper(II) complexes and Na2S2.

Reaction of beta-diketiminate copper(II) complexes and Na2S2 resulted in formation of (mu-eta2:eta2-disulfido)dicopper(II) complexes (adduct formation) or beta-diketiminate copper(I) complexes (reduction of copper(II)) depending on the substituents of the supporting ligands. In the case of sterically less demanding ligands, adduct formation occurred to provide the (mu-eta2:eta2-disulfido)dicopper(II) complexes, whereas reduction of copper(II) took place to give the corresponding copper(I) complexes with sterically more demanding beta-diketiminate ligands. Spectroscopic examinations of the reactions at low temperature using UV-vis and ESR as well as kinetic analysis have suggested that a 1 : 1 adduct LCuII-S-SNa with an end-on binding mode is initially formed as a common intermediate, from which different reaction pathways exist depending on the steric environment of the metal-coordination sphere provided by the ligands.

A functional model for pMMO (particulate methane monooxygenase): Hydroxylation of alkanes with H2O2 catalyzed by beta-diketiminatocopper(II) complexes.

The reaction of copper(II) complexes supported by a series of beta-diketiminate ligands ((R1,R2)L, [(Dipp)N-C(R(2))-C(R(1))-C(R(2))-N(Dipp)](-), Dipp=2,6-diisopropylphenyl; see ) and H(2)O(2) has been examined spectroscopically at a low temperature. The beta-diketiminatocopper(II) complexes with R(2)=H (no substituent on the beta-carbon) provided a copper-oxygen intermediate that exhibited the same spectroscopic features as those of the bis(mu-oxo)dicopper(III) complex generated by the reaction of corresponding beta-diketiminatocopper(I) complex and O(2). On the other hand, the beta-diketiminatocopper(II) complexes with methyl substituent on the beta-carbon (R(2)=Me) did not produce such an intermediate in the same reaction.

Cytochrome c-crown ether complexes as supramolecular catalysts: cold-active synzymes for asymmetric sulfoxide oxidation in methanol.

A series of supramolecular complexes of various cytochrome c proteins with 18-crown-6 derivatives behave as cold-active synzymes in the H2O2 oxidation of racemic sulfoxides. This interesting behavior contrasts with native functionality, where the employed proteins act as electron transfer carriers. ESI-MS.

Chemical activation of cytochrome c proteins via crown ether complexation: cold-active synzymes for enantiomer-selective sulfoxide oxidation in methanol.

Supramolecular complexation with 18-crown-6 significantly converted catalytically inactive cytochrome c (biological form) to catalytically active synzyme (artificial form). Although a family of cytochrome c proteins does not work as enzymes in nature, crown ether complexation modified their heme coordination structures and functionally activated them to promote the asymmetric oxidation of racemic sulfoxides at low temperature. Horse heart, pigeon breast, and yeast cytochrome c proteins were demonstrated to form supramolecular complexes with 18-crown-6 in methanol, which effectively oxidized (S)-isomers of naphthyl methyl sulfoxide, methyl tolyl sulfoxide, isopropyl phenyl sulfoxide, benzyl methyl sulfoxide, and 4-methylsulfenyl acetophenone at -40 degrees C.