The catalytic and photocatalytic autoxidation of Sx2− to SO42− by water-soluble cobalt porphyrin

Research on the self-assembly of exfoliated perovskite nanosheets (LaNb2O7−) and cobalt porphyrin utilized for the electrocatalytic oxidation of ascorbic acid

A sandwich-structured nanocomposite of LaNb₂O₇/CoTMPyP was fabricated via electrostatic interactions between LaNb₂O₇⁻ nanosheets and cobalt porphyrin cations, and the obtained hybrid film exhibited excellent electrocatalytic activities toward AA.

Organometallic sulfur complexes: reactivity of the hydrogen sulfide anion with cobaloximes

The hydrogen sulfide anion selectively and reversibly displaces pyridine in cobaloxime. A rare trisulfido-bridged dinuclear complex was isolated and characterized.

Straightforward route to trans-A2B-corroles bearing substituents with basic nitrogen atoms

We have developed a comprehensive methodology that affords regioisomerically pure trans- A 2 B -corroles bearing substituents with basic nitrogen atoms at meso positions. The corrole formation reaction involves the acid-catalyzed condensation of a dipyrromethane (DPM) and an aldehyde followed by oxidation with DDQ. The optimal conditions for this process were identified by extensive modifications of the previously developed conditions for the synthesis of trans-A2B-corroles with aromatic substituents. In particular three distinct sets of conditions were identified for various specific cases. Pyridine, quinoline and quinoxaline derived aldehydes as well as other aromatic aldehydes with tertiary amine groups in different positions were succesfully used in the condensation involving sterically hindered dipyrromethanes under the following conditions: (First step: CH 2 Cl 2, [DPM] = 33 mM, [aldehyde] = 17 mM, [TFA] = 50 mM, 1h, room temperature, second step: neutralization with Et 3 N , CH 2 Cl 2, dilution 26 times, 1.5 or 1.3 eqs. of DDQ versus DPM). A different set of conditions was developed for the condesation involving sterically unhindered dipyrromethanes: (first step: CH 2 Cl 2, [DPM] = 33 mM, [aldehyde] = 17 mM, [TFA] = 17 mM, 5h, room temperature, second step: neutralization with Et 3 N , CH 2 Cl 2, dilution 26 times, 1 eq of DDQ versus DPM). In this case only aldehydes with the formyl group directly adjacent to the heterocylic ring are efficient substrates; for the remaining aldehydes an extensive scrambling was observed. The condensation of pyridyldipyrromethanes with aldehydes bearing electron-withdrawing substituents (first step: CH 2 Cl 2, [DPM] = 33 mM, [aldehyde] = 17 mM, [TFA] = 67 mM, 1h, room temperature, second step: neutralization with Et 3 N , CH 2 Cl 2, dilution 26 times, 1 eq of DDQ versus DPM) leads to corroles in 2-11 % yield depending on the position of the nitrogen atom. Finally, 10-(4-formylphenyl)-5,15-dimesitylcorrole was obtained and reacted with mesityldipyrromethane, giving the symmetrical corrole dyad in 14% yield. A total of 21 new corroles of type trans- A 2 B were prepared.

Efficient oxidations and photooxidations with molecular oxygen using metal phthalocyanines as catalysts and photocatalysts

Metal phthalocyanines can be very efficient as catalysts and photocatalysts in oxidation reactions using molecular oxygen as oxidant. Different types of soluble low molecular weight or oligomeric and insoluble heterogeneous catalysts and photocatalysts were developed. The heterogeneous metal phthalocyanines exist either impregnated on SiO 2, Al 2 O 3, charcoal and TiO 2 or covalently and coordinatively bound on SiO 2 and organic polymers or ionically bound on an organic ion exchanger. The catalytic oxidations of toxic sulfide and thiol derivative are studied. In addition, toxic phenols were employed as substrates for the photooxidation. Heterogeneous catalysts can exhibit higher activities then low molecular weight phthalocyanines. These systems exhibit a good stability for re-use. Photooxidations are more efficient than oxidations. A Si(IV) phthalocyanine derivative on a polymer ion exchanger is most active and stable. Also some examples for photooxidations in the direction of photochemical synthesis are given.