Book Review: The Scientific Letters and Papers of James Clerk Maxwell. P.M. Harman,ed. Vol. III,Cambridge University Press,Cambridge

Journal of Statistical Physics -     

Die Hydrolyse von 7-anti-substituierten p-Toluolsulfonsäure-[2-endo-und 2-exo-norbornyl]estern. Norbornanreihe. 12. Mitteilung

The Hydrolysis of 7-anti-Substituted 2-endo- and 2-exo-Norbornyl p-Toluenesulfonates The hydrolysis products of the title compounds have been determined. The preparation of the hitherto unknown solvolysis products is described.     

Optimal control for Multi-Conjugate Adaptive Optics

Classic adaptive optics (AO) is now a proven technique that provides a closed loop real time correction of the turbulence. It is generally based on simple and efficient control algorithms. The next AO generation (Multi-Conjugate AO (MCAO) in its various forms and Extreme AO (XAO)) will require more sophisticated control approaches, especially in the case of wide field AO. We present here the concepts behind optimal control. The advantages compared to more standard approaches are stressed. A first experimental validation is presented. To cite this article: C. Petit et al., C. R. Physique 6 (2005).     

Tailor-made surface properties of particles with a hydrophilic or hydrophobic polymer shell mediated by supercritical CO2

Controlling the surface characteristics of inorganic materials with an organic shell is of great interest for control of the properties of the final material. A challenge is thus to be able to deposit a polymer shell with different solvation properties onto the surface of inorganic particles and to have a good control of the thickness of the organic layer without a prefunctionalization of surfaces. We demonstrate, in this paper, a method for coating silica particles (170-550 nm), used as model substrates, with either a hydrophilic (polyethylene glycol) or a hydrophobic polymer (polybutadiene hydroxy terminated) using a supercritical antisolvent process (precipitation from a compressed antisolvent). Several operating parameters were studied to control precisely the thickness of the deposited layer (from 2 to 30 nm), which was characterized using TEM, FESEM, XPS, and UV-visible techniques. This work demonstrates that supercritical antisolvent processes are powerful methods and good alternatives to conventional coating techniques toward the development of hybrid and/or core-shell nanomaterials.     

The benzophenone S1(n,pi*) --> T1(n,pi*) states intersystem crossing reinvestigated by ultrafast absorption spectroscopy and multivariate curve resolution

The well-known benzophenone intersystem crossing from S(1)(n,pi*) to T(1)(n,pi*) states, for which direct transition is forbidden by El-Sayed rules, is reinvestigated by subpicosecond time-resolved absorption spectroscopy and effective data analysis for various excitation wavelengths and solvents. Multivariate curve resolution alternating least-squares analysis is used to perform bilinear decomposition of the time-resolved spectra into pure spectra of overlapping transient species and their associated time-dependent concentrations. The results suggest the implication of an intermediate (IS) in the relaxation process of the S(1) state. Therefore, a two step kinetic model, S(1) --> IS --> T(1), is successfully implemented as an additional constraint in the soft-modeling algorithm. Although this intermediate, which has a spectrum similar to the one of T(1)(n,pi*) state, could be artificially induced by vibrational relaxation, it is tentatively assigned to a hot T(1)(n,pi*) triplet state. Two characteristic times are reported for the transition S(1) --> IS and IS --> T(1), approximately 6.5 ps and approximately 10 ps respectively, without any influence of the solvent. Moreover, an excitation wavelength effect is discovered suggesting the participation of unrelaxed singlet states in the overall process. To go further discussing the spectroscopic relevancy of IS and to rationalize the expected involvement of the T(2)(pi,pi*) state, we also investigate 4-methoxybenzophenone. For this neighboring molecule, triplet energy level is tunable through solvent polarity and a clear correlation is established between the intermediate resolved by multivariate data analysis and the presence of a T(2)(pi,pi*) above the T(1)(n,pi*) triplet. It is therefore proposed that the benzophenone intermediate species is a T(1)(n,pi*) high vibrational level in interaction with T(2)(pi,pi*) state.     

Synthesis, and two photon absorption properties of 7,7'-(iminundecahydro-closo-dodecaborate)-9,9'-(dihexyl)-2,2'-bifluorene

Hybrid organic-inorganic bis-tetrabutylammonium-7,7'-(iminundecahydro-closo-dodecaborate)-9,9'-(dihexyl)-2,2'-bifluorene (5) was prepared, and the influence of the closo-dodecaborate cluster on the two-photon absorption properties of bi-fluorene derivatives was demonstrated.     

Enantioselective Total Synthesis of (−)‐Terengganensine A

A seven‐step enantioselective total synthesis of (?)‐terengganensine A, a complex heptacyclic monoterpene indole alkaloid, was accomplished. Key steps included: a) Noyori's catalytic enantioselective transfer hydrogenation of the iminium salt to set up the absolute configuration at the C21 position; b) a highly diastereoselective C7 benzoyloxylation with dibenzoyl peroxide under mild conditions; and c) an integrated one‐pot oxidative cleavage of cyclopentene/triple cyclization/hydrolysis sequence for the construction of the dioxa azaadamantane motif with complete control of four newly generated stereocenters.     

A Million Turnover Molecular Anode for Catalytic Water Oxidation

Molecular ruthenium‐based water oxidation catalyst precursors of general formula [Ru(tda)(Lⁱ)₂] (tda^2? is [2,2′:6′,2′′‐terpyridine]‐6,6′′‐dicarboxylato; L¹=4‐(pyren‐1‐yl)‐N‐(pyridin‐4‐ylmethyl)butanamide, 1 b ; L²=4‐(pyren‐1‐yl)pyridine), 1 c ), have been prepared and thoroughly characterized. Both complexes contain a pyrene group allowing ready and efficiently anchoring via π interactions on multi‐walled carbon nanotubes (MWCNT). These hybrid solid state materials are exceptionally stable molecular water‐oxidation anodes capable of carrying out more than a million turnover numbers (TNs) at pH 7 with an E_app=1.45 V vs. NHE without any sign of degradation. XAS spectroscopy analysis before, during, and after catalysis together with electrochemical techniques allow their unprecedented oxidative ruggedness to be monitored and verified.