Search results for "Photochromism"
showing 6 items of 36 documents
Synthesis and magnetic properties of an iron 1,2-bisthienyl perfluorocyclopentene photochromic coordination compound
2011
Abstract The coordination compound Fe(BM-4-PTP) 2 (NCS) 2 ⋅2MeOH ( 1 ) including the photoisomerizable ligand BM-4-PTP (1,2-bis(2′-methyl-5′-(pyrid-4″-yl)thien-3′-yl)perfluorocyclopentene) was obtained as an orange powder. The powder turns blue upon photocyclization of the 1,2-bisthienyl photochromic ligand induced by UV light irradiation at room temperature. Photocycloreversion is obtained by visible light irradiation of the material in the solid state. The orange and blue powders were investigated over the temperature range (5–293 K) and pressure range (1 bar–12 kbar) by magnetic susceptibility measurements and variable temperature 57 Fe Mossbauer spectroscopy. The photo-induced colour ch…
Control of the thermal reaction of a photochromic spirobenzopyran by the enzyme-like activity of albumins
1997
Abstract The thermal ring-opening reaction of a negative photochronic spirobenzopyran was investigated in the presence and absence of albumins. In the presence of the proteins, the formation of the merocyanine form from the spiro form is enhanced markedly by two orders of magnitude. The results for five different albumins indicate the enzyme-like activity of the proteins. The influence of pH, temperature and various ligands was examined in detail for bovine serum albumin (BSA) and human serum albumin (HSA). In particular, it was deduced that warfarin shows reversible purely competitive inhibition for BSA with an inhibitor constant K 1 of 1.6×10 −3 M. The results suggest that the catalytic c…
Hybrid Molecular Materials Based upon the Photochromic Nitroprusside Complex, [Fe(CN)5NO]2-, and Organic π-Electron Donors. Synthesis, Structure, and…
2000
An organic/inorganic hybrid salt is obtained by combination of the photochromic nitroprusside complex with the organic donor TTF. The organic part shows an unprecedented 2D organization formed by an orthogonal arrangement of TTF hexamers and monomers. However, the donor layers are formed by pairs of moderately interacting dimeric (TTF)22+ units surrounded by neutral TTF molecules in such a way that the charge is localized and the compound is a semiconductor. Short contacts between the organic layers and the nitroprusside anions are present that may affect the photophysical properties of the nitroprusside.
Light Induced Modifications of Langmuir-Blodgett-Multilayer Assemblies Containing Amphotropic Azocopolymer
1994
Abstract Photochromic LB-multilayers of amphotropic copolymers having rod-like azobenzene moieties as side groups which exhibit thermotropic liquid crystalline behaviour in the bulk have been characterized by UV-VIS spectroscopy as well as by angular dependent and energy dispersive SAXS. Upon irradiation with UV-light the initial optical in-plane anisotropy and the vertical layered structure of LB-films can be destroyed. A new layered structure can be rebuilt on irradiation with visible light or by annealing. Using linearly polarized light for the irradiation an optical anisotropy (POA) has been induced or reversibly modified by a photoselection process.
Efficient Conversion of Light to Chemical Energy : Directional, Chiral Photoswitches with Very High Quantum Yields
2020
Abstract Photochromic systems have been used to achieve a number of engineering functions such as light energy conversion, molecular motors, pumps, actuators, and sensors. Key to practical applications is a high efficiency in the conversion of light to chemical energy, a rigid structure for the transmission of force to the environment, and directed motion during isomerization. We present a novel type of photochromic system (diindane diazocines) that converts visible light with an efficiency of 18 % to chemical energy. Quantum yields are exceptionally high with >70 % for the cis–trans isomerization and 90 % for the back‐reaction and thus higher than the biochemical system rhodopsin (64 %). T…
Reversible Strong Coupling in Silver Nanoparticle Arrays Using Photochromic Molecules
2012
International audience; In this Letter, we demonstrate a reversible strong coupling regime between a dipolar surface plasmon resonance and a molecular excited state. This reversible state is experimentally observed on silver nanoparticle arrays embedded in a polymer film containing photochromic molecules. Extinction measurements reveal a clear Rabi splitting of 294 meV, corresponding to ∼13% of the molecular transition energy. We derived an analytical model to confirm our observations, and we emphasize the importance of spectrally matching the polymer absorption with the plasmonic resonance to observe coupled states. Finally, the reversibility of this coupling is illustrated by cycling the …