Molybdenum-maltolate as a molybdopterin mimic for bioinspired oxidation reaction

A novel cis-dioxomolybdenum(VI)-maltolate [MoO2(Mal)2] (1) is prepared as a stable molybdopterin model for the biomimetic catalysis of the oxidation of hypoxanthine in acetonitrile-water at room temperature. Compound 1 efficiently catalyzes the oxidation reaction of toluene, diphenylmethane, and styrene. Cyto- and oral-toxicity studies suggest its tremendous potential for application as a molybdenum supplement.

Epoxy and Oxidoannulene Oxidation Mechanisms of Fused-Pentagon Chlorofullerenes: Oxides Linked by a Pirouette-Type Transition State

Recently, the oxidative functionalization of double-fused-pentagon (DFP)-containing chlorofullerenes ^#271C₅₀Cl₁₀ and ^#913C₅₆Cl₁₀ was carried out, resulting in two monoepoxides with the oxygen atom added at the ortho site of pentalene on the DFP moiety. To uncover the reactivity of isolated-pentagon-rule violating fullerenes upon oxidation, two possible formation processes (ozone molecule and oxygen radical served as oxidation reagents) of these two oxides were systematically investigated through density functional theory calculations. For the ozone oxidation, two possible pathways were explored, and the results indicate that the biradical mechanism Path_os-RACDP is kinetically more favorable than Path_os-RABP, where R, A, and P represent reactants, ozonide intermediates, and oxidation products and B, C, and D represent another three oxygen-containing intermediates. The products obtained by ozone oxidation ([6,6]-55-closed epoxides P-C₃-C₂₉ for ^#271C₅₀Cl₁₀ and P-C₄₂-C₄₃ for ^#913C₅₆Cl₁₀ with oxygen atom added at the shortest and highest HOMO-contribution bonds) are consistent with experimental observations. However, the oxygen radical additions on these two chlorofullerenes favor generation of the [5,6]-66-open oxidoannulene adducts P-C₃-C₂ and P-C₄₂-C₅₄, respectively. Subsequent analyses of their geometrical features and structural stabilities suggest that these two oxidoannulene adducts are energetically unfavorable and could be converted to more stable epoxides mentioned above by undergoing a pirouette-type transition state. In these two diverse oxidation procedures, the favorable C-C bonds for ozone attacking and C atoms for oxygen-adsorption are rationalized in terms of their bond lengths and HOMO contributions as well as pyramidalization angles.

Analyses of the Binding between Water Soluble C60 Derivatives and Potential Drug Targets through a Molecular Docking Approach

Fullerene C60, a unique sphere-shaped molecule consisting of carbon, has been proved to have inhibitory effects on many diseases. However, the applications of C60 in medicine have been severely hindered by its complete insolubility in water and low solubility in almost all organic solvents. In this study, the water-soluble C60 derivatives and the C60 binding protein’s structures were collected from the literature. The selected proteins fall into several groups, including acetylcholinesterase, glutamate racemase, inosine monophosphate dehydrogenase, lumazine synthase, human estrogen receptor alpha, dihydrofolate reductase and N-myristoyltransferase. The C60 derivatives were docked into the binding sites in the proteins. The binding affinities of the C60 derivatives were calculated. The bindings between proteins and their known inhibitors or native ligands were also characterized in the same way. The results show that C60 derivatives form good interactions with the binding sites of different protein targets. In many cases, the binding affinities of C60 derivatives are better than those of known inhibitors and native ligands. This study demonstrates the interaction patterns of C60 derivatives and their binding partners, which will have good impact on the fullerene-based drug discovery.

Regioselective Oxidation of Fused-Pentagon Chlorofullerenes

Two monoxides of typical smaller chlorofullerenes, (#271)C50Cl10O and (#913)C56Cl10O, featured with double-fused-pentagons, were synthesized to demonstrate further regioselective functionalization of non-IPR (IPR = isolated pentagon rule) chlorofullerenes. Both non-IPR chlorofullerene oxides exhibit an epoxy structure at the ortho-site of fused pentagons. In terms of the geometrical analysis and theoretical calculations, the principles for regioselective epoxy oxidation of non-IPR chlorofullerenes are revealed to follow both "fused-pentagon ortho-site" and "olefinic bond" rules, which are valuable for prediction of oxidation of non-IPR chlorofullerenes.