Surfactant‐directed Pd‐nanoparticle assemblies as efficient nanoreactors for water remediation

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Understanding and controlling the efficiency of Au24M(SR)18 nanoclusters as singlet-oxygen photosensitizers

Atomically precise Au24M(SR)18 clusters were used as singlet-oxygen photosensitizers. Comprehensive kinetic analysis provided insights into the mechanism and driving-force dependence of the quenching of 1O2 by gold nanoclusters

Dipole Moment Effect on the Electrochemical Desorption of Self-Assembled Monolayers of 310-Helicogenic Peptides on Gold

AbstractThe front cover artwork is provided by Pierangelo Gobbo and Flavio Maran, University of Padova (Italy). The image highlights how the orientation of the dipole moment associated with helical peptides affects the electrodesorption potential of the corresponding self‐assembled monolayers. Read the full text of the Article at 10.1002/celc.201600573

Atomically precise Au144(SR)60 nanoclusters (R = Et, Pr) are capped by 12 distinct ligand types of 5-fold equivalence and display gigantic diastereotopic effects

For two decades, Au144(SR)60 has been one of the most studied and used thiolate (SR) protected gold nanoclusters. In many ways, however, it proved to be a challenging and elusive case, also because of the difficulties in solving its structure by single-crystal X-ray crystallography. We used very short thiols and could prepare Au144(SC2H5)60 and Au144(SC3H7)60 in a very pure form, which was confirmed by UV-vis absorption spectroscopy and very regular electrochemistry patterns. Inductively coupled plasma and electrospray ionization mass spectrometries gave definite proof of the Au144(SR)60 stoichiometry. Highresolution 1D and 2D NMR spectroscopy in the solution phase provided the result of assessing the presence of 12 ligand types in exactly the same amount (5-fold equivalence). Equally important, we found that the two protons belonging to each methylene group along the thiolate chain are diastereotopic. For the a-CH2 protons, the diastereotopic effect can be indeed gigantic, as it reaches chemical-shift differences of 2.9 ppm. DFT calculations provided insights into the relationship between structure and NMR results. In particular, the 12 ligand types and corresponding diastereotopic effects may be explained by considering the presence of C\u2013H/S hydrogen bonds. These results thus provide fundamental insights into the structure of the thiolate layer capping this long-studied gold nanocluster

The Role and Relevance of the Transfer Coefficient Alpha in the Study of Dissociative Electron Transfers. Concepts and Examples from the Electroreduction of Perbenzoates

The electrochemical transfer coefficient R is shown to be a sensitive probe of the mechanism by which electron transfer and bond cleavage may be coupled in dissociative electron transfers. R is particularly useful in detecting the transition between stepwise and concerted dissociative electron transfers. Whereas linear potential dependencies of R are in agreement with either mechanism, a mechanism transition can be evidenced upon observation of a nonlinear R pattern. Under favorable circumstances, a wavelike potential dependence of R can be observed. This is a function of main parameters describing the mechanism competition such as, in particular, the difference between the two relevant standard potentials, the intrinsic barriers, and the preexponential factors of the two rate-constant equations. The analysis of R was applied to study the electroreduction of a series of perbenzoates, XC6H4CO3But, in DMF. The reduction leads to the irreversible cleavage of the O-O bond. The R data were obtained by cyclic voltammetry followed by convolution analysis. For all compounds investigated, the experimental trend could be simulated satisfactorily by reasonable selection of the main parameters. Whereas the analysis showed that the reduction of the unsubstituted peroxide proceeds by a pure concerted mechanism, a stepwise mechanism holds when X ) 4-NO2. On the other hand, R-wave patterns were found for X ) 4-COMe and 3-NO2, as previously described for X ) 4-CN. For the latter compounds, the R analysis is in agreement with a dissociative electron transfer process in which the mechanism changes from stepwise to concerted by increasing the applied potential. Finally, although the reduction of the 4-OCOMe perbenzoate basically occurs by a concerted mechanism, a transition pattern seems to emerge at the most negative potentials explored. Further support to the experimental outcome and conclusions was provided by studying the temperature effect on the reduction of the 4-COMe derivative, which led to the expected shift toward the stepwise mechanism by lowering the temperature