Cesium carbonate supported on hydroxyapatite coated Ni_(0.5)Zn_(0.5)Fe_2O_4 magnetic nanoparticles as an efficient and green catalyst for the synthesis of pyrano[2,3-c]pyrazoles

Cesium carbonate supported on hydroxyapatite coated Nio.sZno.sFe2O4 magnetic nanoparticles （Nio.sZno.sFe2O4@Hap-Cs2CO3） was found to be magnetically separable, highly efficient, green and recyclable heterogeneous catalyst. The synthesized nanocatalyst has been characterized with several methods （FT-IR, SEM, TEM, XRD and XRF） and these analyzes confirmed which the cesium carbonate is well supported to catalyst surface. After full characterization, its catalytic activity was investigated in the synthesis of pyranopyrazole derivatives and the reactions were carried out at room temperature in 50：50 water/ethanol with excellent yields （88-95%）. More importantly, the Nio.5Zno.sFe204@Hap-Cs2CO3 was easily separated from the reaction mixture by external magnetic field and efficiently reused at least six runs without any loss of its catalytic activity. Thus, the developed nanomagnetic base catalyst is potentially useful for the green and economic production of organic compounds.

Significant Heterogeneous Carbonate Salt Catalyzed Acetylation of Alcohols via a Transesterification Process with Carbonate Salt-activated Alcohol 1H NMR Evidence

Heterogeneous carbonate salt catalyzed acetylation of alcohols via a transesterification process has been devel- oped. Various esters are furnished up to 97% yield. Established procedure is simple and air-tolerant with readily available reagents. Ethyl acetate and isobutyl acetate are used as not only acetylating agents, but also reaction sol- vents in transesterification. Aliphatic linear alcohols, allylic alcohols and benzyl alcohols show high reactivities in the presence of 1 or 5 mol% Cs2CO3 at 125 ℃. Cesium carbonate can be recycled by pumping liquid phase out of reactor after reaction. During four cycle runs for reaction of 2-phenylethanol and ethyl acetate, high yields of phenethyl acetate are provided （〉60% yield）. Based on experiments and 1H NMR investigation, bifunctional catalysis is proposed, alcohol activated by carbonate ion is confirmed, and higher activity of catalytic amount than stoichiometric cesium carbonate is interpreted.

Significantly enhanced of tungsten diselenide functionalization optoelectronic performance phototransistor via surface

Two-dimensional （2D） layered transition metal dichalcogenides （TMDs） have attracted enormous research interests and efforts towards the development of versatile electronic and optical devices, owing to their extraordinary and unique fundamental properties and remarkable prospects in nanoelectronic applications. Among the TMDs, tungsten diselenide （WSe2） exhibits tunable ambipolar transport characteristics and superior optical properties such as high quantum efficiency. Herein, we demonstrate significant enhancement in the device performance of WSe2 phototransistor by in situ surface functionalization with cesium carbonate （Cs2CO3）. WSe2 was found to be strongly doped with electrons after Cs2CO3 modification. The electron mobility of WSe2 increased by almost one order of magnitude after surface functionalization with 1.6-nm-thick Cs2CO3 decoration. Furthermore, the photocurrent of the WSe2-based phototransistor increased by nearly three orders of magnitude with the deposition of 1.6-nm-thick Cs2CO3. Characterizations by in situ photoelectron spectroscopy techniques confirmed the significant surface charge transfer occurring at the Cs2COB/WSe2 interface. Our findings coupled with the tunable nature of the surface transfer doping method establish WSe2 as a promising candidate for future 2D materials- based optoelectronic devices.