含膦配体的铂羰基配合物催化苯的光羰化反应

采用“原位反应”的方法,研究了配合物Ｐｔ（ＰＭｅ３）２（ＣＯ）２和Ｐｔ（ｄｉｐｈｏｓ）（ＣＯ）２（ｄｉｐｈｏｓ：１,２－二（二特丁基膦）乙烷,即ｄ（ｔ－Ｂｕ）Ｐｅ,１,２－二（二环己基膦）乙烷,即ｄＣｙｈＰｅ;１,２－二（二环戊基膦）乙烷,即ｄＣｙｐＰｅ;１,２－二（苯基特丁基膦）乙烷,即Ｐｈ（ｔ－Ｂｕ）Ｐｅ）在室温和压下对苯的光羰化反应性能,得到了预期的反应产物苯甲醛和苯甲醇。它们均经色－质分析     

A novel light induced Knoevenagel condensation of Meldrum’s acid with aromatic aldehydes in aqueous ethanol

A highly efficient environment-friendly photochemical methodology has been developed for the condensation of Meldrum’s acid with aromatic aldehydes in water-ethanol solution sans any catalyst, support or promoter.     

Rapid access to cis-cyclobutane γ-amino acids in enantiomerically pure form

The (+)-(1R,2S) and (−)-(1S,2R) stereoisomers of 2-(aminomethyl)cyclobutane-1-carboxylic acid have been prepared using a short and efficient strategy, which employs the photochemical [2+2] cycloaddition reaction between ethylene and an unsaturated γ-lactam as the key step.     

Sputter deposition of high transparent TiO2−xNx/TiO2/ZnO layers on glass for development of photocatalytic self-cleaning application

In this study, TiO_2−xN_x/TiO₂ double layers thin film was deposited on ZnO (80 nm thickness)/soda-lime glass substrate by a dc reactive magnetron sputtering. The TiO₂ film was deposited under different total gas pressures of 1 Pa, 2 Pa, and 4 Pa with constant oxygen flow rate of 0.8 sccm. Then, the deposition was continued with various nitrogen flow rates of 0.4, 0.8, and 1.2 sccm in constant total gas pressure of 4 Pa. Post annealing was performed on as-deposited films at various annealing temperatures of 400, 500, and 600 °C in air atmosphere to achieve films crystallinity. The structure and morphology of deposited films were evaluated by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and atomic force microscopy (AFM). The chemical composition of top layer doped by nitrogen was evaluated by X-ray photoelectron spectroscopy (XPS). Photocatalytic activity of samples was measured by degradation of Methylene Blue (MB) dye. The optical transmittance of the multilayer film was also measured using ultraviolet-visible light (UV-vis) spectrophotometer. The results showed that by nitrogen doping of a fraction (∼1/5) of TiO₂ film thickness, the optical transmittance of TiO_2−xN_x/TiO₂ film was compared with TiO₂ thin film. Deposited films showed also good photocatalytic and hydrophilicity activity at visible light.     

Promotion of nano-anatase TiO2 on the spectral responses and photochemical activities of D1/D2/Cyt b559 complex of spinach

Previous researches approved that photocatalysis activity of nano-TiO₂ could obviously increase photosynthetic effects of spinach, but the mechanism of improving light energy transfer and conversion is still unclear. In the present we investigated effects of nano-anatase TiO₂ on the spectral responses and photochemical activities of D1/D2/Cyt b559 complex of spinach. Several effects of nano-anatase TiO₂ were observed: (1) UV–vis spectrum was blue shifted in both Soret and Q bands, and the absorption intensity was obviously increased; (2) resonance Raman spectrum showed four main peaks, which are ascribed to carotene, and the Raman peak intensity was as 6.98 times as that of the control; (3) the fluorescence emission peak was blue shifted and the intensity was decreased by 23.59%; (4) the DCPIP photoreduction activity showed 129.24% enhancement; (5) the oxygen-evolving rate of PS II was elevated by 51.89%. Taken together, the studies of the experiments showed that nano-anatase TiO₂ had bound to D1/D2/Cyt b559 complex, promoted the spectral responses, leading to the improvement of primary electron separation, electron transfer and light energy conversion of D1/D2/Cyt b559 complex.     

Synthesis of Iridoid Monoterpenes and Prostaglandins,via Photochemical Rearrangement of Bicyclo[2.2.1]hept‐5‐en‐2‐One

The synthesis of cyclopentanoid natural products, iridoid monoterpenes and prostaglandins, was achieved from a common intermediate 2 , which was obtained from 1 via photochemical rearrangement.     

Approaches to the preparation of (Z)-1,2-difluorostilbenes

Methodology directed at the preparation of (Z)-1,2-difluorostilbenes has been evaluated. For symmetrical (Z)-1,2-difluorostilbenes, photochemical isomerization of the isomeric (E)-1,2-difluorostilbenes, and HPLC separation of the mixture of stilbene isomers is a reasonable route to a particular (Z)-stilbene. An alternative approach to both symmetrical and/or unsymmetrical (Z)-1,2-difluorostilbenes has been developed via stereospecific Pd(0) coupling of (E)-1,2-difluoro-aryl-ethenyltributylstannanes under Stille-Liebiskind conditions with aryl idodies. The requisite arylstannanes can be obtained via the reported route developed by Davis or via (E)-1,2-difluorovinyltributylstannane - a new route described in this work. The methodology tolerates almost any functionality in the aryl ring, is easily carried out, is stereospecific and provides the first general route to (Z)-1,2-difluorostilbenes.     

Detection of Human Serum Albumin by a Photoinduced Fluorogenic Reaction

ABSTRACT

9,10-anthraquinone (AQ), a photochemically reactive substrate, has been conjugated together with human serum albumin (HSA), and the photoinduced fluorogenic reaction of the HSA-AQ conjugate was studied. This conjugate shows a greatly enhanced photochemical fluorimetric activity compared with that of free AQ. The spectral characteristics of the photoreduction product of the HSA-AQ conjugate was investigated and large blue shifts in both the excitation and emission bands, compared with those of free AQ, were observed. The kinetic behavior of the photoinduced fluorogenic reaction and the effects of some experimental conditions were also investigated. The enhancement in the photoinduced fluorogenic reactivity of HSA-AQ was utilized in the sensitive detection of HSA by a simple in-situ photoinduced kinetic fluorimetric method. The calibration graph was linear over the range 0-1.0x10^?6 mol/L HSA. The detection limit was 6.5x10^?10 mol/L HSA and the relative standard deviation was 2.7% for 6.0x10^?8 mol/L HSA (n=6).     

Enhancement of photochemical response in bulk poly(methyl methacrylate) photopolymer dispersed organometallic compound

The enhancement of photochemical response is investigated in Zinc methylacrylate organometallic compound and phenathrenequinone doped poly(methyl methacrylate) photopolymer experimentally and theoretically. In experiments, the improvement in photosensitivity due to ZnMA compound is presented quantitatively. The dynamics parameters, quantum yield and initiation rate of PQ molecules, are determined by nonlinear fitting the experimental curves. The theoretical model with nonlocal effect is proposed to explain the contribution of actual chemical process to the enhancement of photochemical response. The comparison of theoretical and experimental results is finally described. Two significant roles of ZnMA compound, as a catalyst to accelerate the photochemical reaction and as a reactant to participate in the photoattachment with PQ molecules, are demonstrated quantitatively. The time constant of grating formation 20.9 s and the photosensitivity 2.3×10⁻⁵ cm²/J are experimentally obtained in an optimized 0.1 wt% ZnMA doped PQ-PMMA sample. This study contributes the physical mechanism for improvement of photosensitivity and provides significant theoretical foundation for advance the properties of materials in holographic memory.     

Stability of twisted diarylnitroxides: Photochemical tests

Photochemical stability and possible routes for photodegradation of twisted diarylnitroxides were determined. It was shown that quantum yields for twisted diarylnitroxides fall in the range typical for the best representatives of alkylnitroxides providing an additional support that twisting of the phenyl ring from the N-O conjugation plane constitutes an efficient route for increasing thermo and photo stability of the nitroxides.