نتایج جستجو برای: isomerisation

تعداد نتایج: 423  

Journal: :Chemical communications 2016
Jaume Garcia-Amorós M Cidália R Castro Paulo Coelho M Manuela M Raposo Dolores Velasco

Push-pull bithienylpyrrole-based azo dyes exhibit thermal isomerisation rates as fast as 1.4 μs in acetonitrile at 298 K becoming, thus, the fastest neutral azo dyes reported so far. These remarkably low relaxation times can be transferred into liquid-crystalline matrices enabling light-triggered oscillations in the optical density of the final material up to 11 kHz under ambient conditions.

Journal: :Chemical communications 2014
T Hahn E V Kondratenko D Linke

The kind of surface MoOX structures on Al2O3-SiO2 was found to determine propene selectivity in the metathesis of ethylene and 2-butene. Compared to isolated tetrahedral MoOX species, their polymerized octahedral counterparts show significantly lower activity for isomerisation of 2- to 1-butene thus hindering non-selective metathesis of these butenes. In addition, they reveal higher ability to ...

Journal: :Physical chemistry chemical physics : PCCP 2015
Tanmay Chatterjee Mrinal Mandal Venkatesh Gude Partha Pratim Bag Prasun K Mandal

Z-E Isomerisation because of rotation around the exocyclic double bond (known as the τ-twist) and not any other internal conversion has been reported to be the major nonradiative decay channel for non-hydroxylic unconstrained para and meta GFP chromophore analogues. The equation Φf + 2ΦZE = 1 has been shown to hold well for both para and meta GFP chromophore analogues. If the above equation hol...

Journal: :Chemical communications 2014
Anja Köhntopp Alexandra Dabrowski Michal Malicki Friedrich Temps

The photochemical behaviour of functionalised gold nanoparticles (AuNPs) carrying azobenzenethiolate-alkylthiolate monolayers was investigated. Repeated trans-cis and cis-trans isomerisation cycles could be performed in all cases with high efficiency. Reversible photoinduced aggregation was observed when azothiolates with long alkyl spacers (≥C7) were combined with short (C5) alkylthiolate coli...

Journal: :Chemical communications 2010
Juri Ugolotti Gerald Kehr Roland Fröhlich Gerhard Erker

Bis(alkynyl)silanes (1a,b) react with bis(pentafluorophenyl)-borane to 3-boryl-2,5-bis(trimethylsilyl) substituted siloles 3a,b. Subsequent irradiation of 3 with Pyrex filtered UV light resulted in the complete conversion to the new 5-boryl-2,3-bis(trimethylsilyl) substituted siloles 4a,b.

Journal: :Chemical communications 2010
Thomas Harwardt Giancarlo Franciò Walter Leitner

A fully integrated continuous process for homogeneous catalysed reactions in scCO(2) has been developed exploiting the tunable solvent properties of scCO(2). A heated condenser situated above the reaction zone leads to a phase split under isobaric conditions resulting in efficient catalyst retention and recirculation. Continuous isomerisation of allylic alcohols was carried out for over 200 hou...

Journal: :Physical chemistry chemical physics : PCCP 2014
Falk Renth Ron Siewertsen Frank Strübe Jochen Mattay Friedrich Temps

Femtosecond broadband transient absorption spectroscopy has been used in a comparative study of the ultrafast photo-induced Z → E isomerisation reactions of four photochromic furylfulgides with selected structural motifs in n-hexane as solvent. The results show that all studied Z-fulgides exhibit fast and direct processes along barrierless excited-state pathways involving a conical intersection...

Journal: :Chemical communications 2012
Etienne Mazoyer Kai C Szeto Jean-Marie Basset Christopher P Nicholas Mostafa Taoufik

The first example of propylene production from 2-butene in promising yield is described by reacting trans-2-butene over tungsten hydrides precursor W-H/Al(2)O(3) at 150 °C and different pressures in a continuous flow reactor. The tungsten carbene-hydride active site operates as a "bi-functional catalyst" through the disfavoured 2-butene isomerisation on W-hydride and 2-butenes/1-butene cross-me...

Journal: :Beilstein Journal of Organic Chemistry 2008
David M Hodgson Leonard H Winning

Tandem deoxygenation-neophyl-type radical rearrangement-electrophile trapping using xanthates from 7-azabenzonorbornadienes gives 3-exo-substituted 2-aza-5,6-benzonorbornenes, which in some cases undergo isomerisation to (aminomethyl)indenes. The starting xanthates are accessible in good yields and high enantiomeric ratios via asymmetric hydroboration of (aryne/pyrrole-derived) 7-azabenzonorbor...

Journal: :Chemical communications 2016
L Möckl A Müller C Bräuchle T K Lindhorst

We have shown previously that carbohydrate-specific bacterial adhesion to a non-physiological surface can be photocontrolled by reversible E/Z isomerisation using azobenzene-functionalised sugars. Here, this approach is applied to the surface of human cells. We show not only that bacterial adhesion to the azobenzene glycoside-modified cell surface is higher in the E than in the Z state, but add...

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