Through a self-assembly of arginine/lysine-rich peptide from human papillomavirus (HPV) capsid protein and an Eu-containing polyoxometalate (POM), Na 9 [EuW 10 O 36 ]•32H 2 O (EuW10), the formation of well-defined hybrid nanospheres in aqueous solution is presented, showing large luminescence enhancement of POM and use as a potential "turn-on" fluorescence probe in biology. The binding mechanisms between them have been explored at the molecular level by using transmission electron microscopy (TEM), scanning electron microscopy (SEM), fluorescence spectra, isothermal titration calorimetry (ITC), ζ-potential, and nuclear magnetic resonance ( 1 H NMR) titration spectra. ITC study confirmed the assembly was completely enthalpy driven, and ζ-potential proved that the driving force was governed mainly by the electrostatic interaction. 1 H NMR spectroscopy indicated changes in hydrogen bond of EuW10 and the peptide segment, and the binding model was clarified. Our design constructed the self-assembly fabrication of well-defined nanoparticles by using inorganic POM and bioapplicable peptide combined with strong fluorescence characterization together. The enhanced luminescence and specific targeted-HPV peptide ability would be important and useful in the detection of HPV capsid protein and/or HPV genotypes, and such a protocol could be extended to another virus once using the corresponding peptides. Therefore, the present report will be helpful to promote the development of antivirus agents in the future.

The epoxidation of allylic alcohols with H2O2 catalyzed by the hybrid [α-B-SbW9O33( t BuSiO)3Ti­(OiPr)]3– (1) anion as a molecular model of heterogeneous Ti-silicalite TS-1 catalyst was analyzed by means of DFT to determine the main factors that control the catalytic process and, finally, to improve the value of the available catalysts. Our calculations revealed that unlike other alkenes, allylic alcohols can bind the Ti center after activation of the precatalyst via hydrolysis to give the corresponding Ti-alcoholate, which is the catalyst resting state. Next, the dissociative addition of hydrogen peroxide to Ti causes the cleavage of a Ti–OSi junction to form a Ti­(η2-OOH) moiety. The partial detachment of the Ti from the catalyst structure yields an intermediate with a flexible Ti center from which the Ti-OOH group can transfer an electrophilic oxygen to the alkene substrate in an inner-sphere fashion. The rate-determining process, which involves the heterolytic activation of H2O2 over the Ti­(IV) and the electrophilic O-transfer, accounts for an overall free-energy barrier of 23.0 kcal mol–1 for 2-methyl-2-buten-1-ol, in line with the experimental value of 22.3. Conversely, the outer-sphere O-transferalso accessible to nonfunctionalized alkenesoccurs through a more strained transition state that lays above in energy (by ∼4 kcal mol–1), giving a clue to explain the low yields reported experimentally for nonfunctionalized olefins. We also found that reducing the bulkiness of the substituents in the silanol functions of the catalyst has a positive influence on the catalytic activity, decreasing the overall free-energy barriers for the outer-sphere path. With this knowledge, we developed other catalytic species with tailored steric properties based on [SbW9O33(RSiOH)3]3– structure (R = i Pr and n Pr), which were synthesized, characterized, and successfully applied to the catalytic epoxidation of unfunctionalized alkenes. Present results clearly show that the detailed knowledge of the reaction mechanisms, even for complex processes, is possible nowadays and that the acquired information allows designing catalysts with desired activities.

We report on a site-isolated model for Ti(IV) by reacting [Ti( i PrO) 4 ] with the silanolfunctionalized polyoxotungstates [XW 9 O 34-x ( t BuSiOH) 3 ] 3-(X= P, x=0, 1; X= Sb, x=1, 2) in tetrahydrofuran. The resulting titanium(IV) complexes [XW 9 O 34-x ( t BuSiO) 3 Ti(O i Pr)] 3-(X= P, 3; X= Sb, 4) were obtained in monomeric forms both in solution and in the solid state, as proved by diffusion NMR experiments and by X-ray crystallographic analysis. Anions 3 and 4 represent