Search

The electrochemistry and pyridine binding reactions of different porphyrin-crrole dyads are investigated by cyclic voltammetry and thin-layer spectroelecrochemistry in pyridine. Up to four pyridine ligands can be coordinated to each dyad, with the exact value depending upon the metal oxidation state and type of spacer.

The synthesis of a novel family of heterobinuclear cofacial biphenylene (B), anthracene (A), 9,9-dimethylxanthene (X) or dibenzofuran (O) bridged porphyrin-corrole complexes, (PCY)MCICoCl, is reported, M being either an iron(III) or manganese(III) ion. Each complex is characterized by electrochemistry, mass spectrometry, UV-vis, IR, and electron spin resonance spectroscopy.

The synthesis and characterization of cofacial copper biscorroles and porphyrin-corroles linked by a biphenylenyl or anthracenyl spacer are described. The comparative study of four cofacial copper bis-corrole) BC and porphyrin-corrole (PC) dyads and their related monomeric corrole and porphyrin units shows that electron interaction between the two face-to-face macrocycles of these cofacial derivatives depends critically on the type and size of rigid spacer.

Research has been conducted on the cofacial biscorroles and linked Co(II) porphyrins and Co(III) corroles. The synthesis and characterization of these compounds with the same face to face orientation are discussed.

Research has been conducted on the cyclam-based manganese(II) complexes. The electrochemical, EPR and variable-temperature magnetism data of [(tmc)MnCl]. X have been investigated and the results are reported.

Research has been conducted on the (BCA)Co (sub)2 and (BCB)Co (sub)2 where BCA and BCB are biscorroles linked by anthracenyl and biphenyl bridge. The synthesis, spectroscopic properties and electrochemistry of these compounds have been investigated, and the effect of the anthracenyl and biphenyl bridge on the ligand binding properties has been examined.

An experiment was conducted to examine the electrochemistry and ozonation reactions of manganese (III) dodecaphenylporphyrins compounds and their derivatives. Nuclear magnetic resonance (NMR) and UV-visible spectra were performed on the compounds using UV and NMR spectroscopy. Results showed that each (P)MnCl derivative can exist in five different oxidation states and that all compounds are stable in their neutral form and even during the addition of three electrons.

UV-visible, 1H NMR, and IR spectroscopic studies of several neutral, oxidized heteroleptic phthalocyaninato and porphyrinato complexes of Zr(IV) and Hf(IV) indicate that these double-decker complexes undergo ring-centered reversible oxidation and reduction reactions. The nature of the porphyrin ring influences the half-wave potentials of both the reactions, which also depend on ion size during oxidation. A decrease in ionic radius facilitates easy oxidation.

The diprotonated form of a fluorinated free base porphyrin, 5-(p-aminophenol)-10,15,20-tris(pentafluorophenyl)porphyrin ([H.sub.2]FAP), has catalyzed the reduction of oxygen by a weak electron donor like ferrocene (Fc). Spectrophotometric measurements performed in 1,2-dichloroethane solutions have shown that reduction of oxygen by Fc catalyzed by [H.sub.4][FAP.sup.2+] has occurred in the presence of the tetrakis(pentafluorophenyl)borate ([TB.sup.-]) counteranion in the organic phase.

Laser flash photolysis measurements are utilized to examine the dynamics of photoinduced electron transfer from the singlet excited state of porphyrin tripod (TP[Zn.sub.3]) to pyridine moiety (Py[C.sub.60]). The efficient intracomplex photoinduced electron transfer in TP[Zn.sub.3]-Py[C.sub.60] in nonpolar solvents is attributed to the [pi]-[pi] interactions between the porphyrin and fullerene moieties, together with intramolecular [pi]-bond formation between the porphyrin radical cation and the neutral porphyrin in TP[Zn.sub.3.sup.*+].

Molecular electrocatalysis for oxygen reduction at a polarized water/1,2-dichloroethane (DCE) interface is analyzed, which has involved aqueous protons, ferrocene (Fc) in DCE and amphiphilic cobalt porphyrin catalysts adsorbed at the interface. The reaction is shown to be electrocatalytic as its rate has depended on the applied Galvani potential difference between the two phases.

Cobalt porphine (CoP) dissolved in the organic phase of a biphasic system is used for catalyzing [O.sub.2] reduction by an electron donor, ferrocene (Fc). Voltammetry is used at the interface between two immiscible electrolyte solutions (ITIES) to drive this catalytic reduction at the interface as a function of the applied potential difference, where aqueous protons and organic electron donors have combined to reduce [O.sub.2].

A series of manganese(III) corroles are examined as to their electrochemistry and spectroschemistry in nonaqueous solvents. Complexation with one or two anionic axial ligands has led to an easier oxidation and a harder reduction as compared to the uncomplexed four-coordinate species.

A study was conducted to determine the use of Co(III) corroles as efficient catalysts for the reduction of dioxygen in the presence of perchloric acid in both heterogeneous and homogeneous systems. The results showed that cobalt corroles could be used as effective catalysts in the reduction of [O.sub.2] with HCl[O.sub.4] via the redox couple between Co(III) corroles and Co(III) corrole radical cations.

A polytopic cyclam-bis-terpyridine ligand is used for accomplishing an acid-base-triggered formation of either a mononuclear neutral complex or metallopolymers with [Cu.sup.2+] ions. The controlled interconversion between the two forms is achieved through the reversible displacement of a [Cu.sup.2+] cation from the macrocycle to the terpyridine units.

Three face-to-face linked porphyrin-corrole dyads are investigated as to their electrochemistry, spectroelectrochemistry, and chloride-binding properties in dichloromethane or benzonitrile. An axial binding of one or two Cl(super -) ligands to the cobalt center of the corrole is observed for singly and doubly oxidized (PCY)H2Co, with the exact stoichiometry of the reaction depending upon the spacer size and the concentration of Cl(super -) added to solution.

Research has been conducted on alkyl- and aryl-substituted corroles. The authors have investigated the effect of solvents on spectroscopic properties and electrochemistry of these compounds in nonaqueous media.