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Robert S.L. Chapman Molly Francis Ruth Lawrence Joshua D. Tibbetts Steven D. Bull 《Tetrahedron》2018,74(44):6442-6452
Formyloxyacetoxyphenylmethane, symmetric 1,1-diacylals and mixed 1-pivaloxy-1-acyloxy-1-phenylmethanes have been used as moisture stable O-formylating and O-acylating reagents for primary and secondary alcohols, allylic alcohols and phenols under solvent/catalyst free conditions to afford their corresponding esters in good yield. 相似文献
234.
The Structure of [HSi9]3− in the Solid State and Its Unexpected Highly Dynamic Behavior in Solution
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Corinna Lorenz Florian Hastreiter Dr. Johnny Hioe Dr. N. Lokesh Dr. Stefanie Gärtner Prof. Dr. Nikolaus Korber Prof. Dr. Ruth M. Gschwind 《Angewandte Chemie (International ed. in English)》2018,57(39):12956-12960
We report on the first unambiguous detection of the elusive [HSi9]3? anion in solutions of liquid ammonia by various 29Si and 1H NMR experiments including chemical exchange saturation transfer (CEST). The characteristic multiplicity patterns of both the 29Si and 1H resonances together with CEST and a partially reduced 1H,29Si coupling constant indicate the presence of a highly dynamic Si8 entity and a Si?H moiety with slow proton hopping. Theoretical calculations corroborate both reorganization of Si8 on the picosecond timescale via low vibrational modes and proton hopping. In addition, in a single‐crystal X‐ray study of (K(DB[18]crown‐6))(K([2.2.2]crypt))2[ HSi9 ]?8.5 NH3, the H atom was unequivocally localized at one vertex of the basal square of the monocapped square‐antiprismatic cluster. Thus experimental studies and theoretical considerations provide unprecedented insight into both the structure and the dynamic behavior of these cluster anions, which hitherto had been considered to be rigid. 相似文献
235.
Chang‐Keun Lim Melissa Maldonado Robert Zalesny Rashid Valiev Hans gren Anderson S. L. Gomes Jie Jiang Ruth Pachter Paras N. Prasad 《Advanced functional materials》2020,30(16)
A concept of interlayer‐sensitized photoluminescence (PL) of quasi‐2D hybrid perovskite (PVK) with a π‐conjugated optically interacting organic cation layer is introduced and demonstrated. A rod‐shaped aggregation‐induced enhanced emission (AIEE) organic cation (BPCSA+), well fitted into the lattice size of 2D PVK layers, is designed and synthesized to prolong the exciton lifetime in a condensed layer assembly in the PVK. The BPCSA+ promotes the PL of this hybrid PVK up to 10‐folds from that of a non‐π‐conjugated organic cation (OA) 2D PVK. Notably, different from PL of OA 2D PVK, the increased PL intensity of BPCSA 2D PVKs with an increase of the BPCSA ratio in the PVK indicates a critical photon‐harvesting contribution of BPCSA. The films of BPCSA 2D PVKs are incredibly stable in ambient environments for more than 4 months and even upon direct contact with water. Additionally, due to the strong two‐photon absorption property of BPCSA, the BPCSA 2D PVK displays superior emission properties upon two‐photon excitation with a short wavelength IR laser. Thus, the AIEE sensitization system for quasi‐2D PVK hybrid system can make a drastic improvement in performance as well as in the stability of the PVK emitter and PVK based nonlinear optical devices. 相似文献
236.
Elemental fluorine and acetyl hypofluorite, labeled with 18F, were added to eight simple aryl-tin derivatives. Both reagents gave good radiochemical yields of labeled aryl fluorides. Overall, acetyl hypofluorite gave more consistent yields (~70%), while F2 gave more variable yields (54% – 95%). 相似文献
237.
The kinetics of the mercuration of 2-methylazobenzene in methanol were studied. The thermodynamic data found were ?Eact = 22.7 kcal mol?1, ?H1 = 22.0 kcal mol?1, and ?S1 = ?12.3 eu. In comparison with a value of ?S1 ? ?20 eu for the mercuration of benzene, this lowered entropy is taken as evidence for complex formation between mercuric acetate and 2-methylazobenzene before and during the rate determining step of electrophilic substitution. 相似文献
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Davies SG Sheppard RL Smith AD Thomson JE 《Chemical communications (Cambridge, England)》2005,(30):3802-3804
The beta-amino acid cispentacin promotes the Hajos-Parrish-Eder-Sauer-Wiechert reaction with levels of enantioselectivity comparable to or higher than proline. 相似文献