A series of neutral bimetallic lanthanide aryloxides p-C6H4[OLnL(THF)n]2 [Ln = Y(1), Yb(2), Sm(3)(n = 1) and La(4)(n = 2), L = Me2NCH2CH2N{CH2-(2-O–C6H2–tBu2-3,5)}2] and alkoxides p-C6H4CH2[OLnL(THF)]2 [Ln = Y(5), Yb(6)] supported by an amine-bridged bis(phenolate) ligand have been synthesized through one-pot reactions of Ln(C5H5)3(THF), LH2 with p-benzenediol and 1,4-benzenedimethanol, respectively. All complexes have been fully characterized by elemental analyses, single-crystal X-ray diffraction analysis, and IR and multi-nuclear NMR spectroscopy(in the cases of 1, 4 and 5). Study of their catalytic behavior revealed that, in general, all complexes are efficient initiators for the polymerization of rac-lactide(LA) and rac-β-butyrolactone(BBL), except for 3 and 4 in the case of BBL. The influence imposed by lanthanides of different ionic radii and initiating groups of different structures on the activity, controllability, and stereoselectivity of polymerization were systematically studied and compared. Highly heterotactic PLA(Pr up to 0.99) and syndiotactic PHB(Pr ≈ 0.81) with high molecular weight and narrow polydispersity formed and were automatically capped with hydroxyl functionality at both ends. 相似文献
Well‐dispersed core–shell Ru@M (M=Co, Ni, Fe) nanoparticles (NPs) supported on carbon black have been synthesized via a facile in situ one‐step procedure under ambient condition. Core‐shell Ru@Co NPs were synthesized and characterized for the first time. The as‐synthesized Ru@Co and Ru@Ni NPs exhibit superior catalytic activity in the hydrolysis of ammonia borane compared with their monometallic and alloy counterparts. The Ru@Co/C NPs are the most reactive, with a turnover frequency (TOF) value of 320 (mol min?1) molRu?1 and activation energy (Ea) of 21.16 kJ mol?1. Ru@Ni/C NPs are the next most active, whereas Ru@Fe/C NPs are almost inactive. Additionally, the as‐synthesized NPs supported on carbon black exhibit higher catalytic activity than catalysts on other conventional supports, such as SiO2 and γ‐Al2O3. 相似文献
The chemical state of a transition‐metal dopant in TiO2 can intrinsically determine the performance of the doped material in applications such as photocatalysis and photovoltaics. In this study, manganese‐doped TiO2 is fabricated by a near‐equilibrium process, in which the TiO2 precursor powder precipitates from a hydrothermally obtained transparent mother solution. The doping level and subsequent thermal treatment influence the morphology and crystallization of the TiO2 samples. FTIR spectroscopy and X‐ray photoelectron spectroscopy analyses indicate that the manganese dopant is substitutionally incorporated by replacing Ti4+ cations. The absorption band edge can be gradually shifted to 1.8 eV by increasing the nominal manganese content to 10 at %. Manganese atoms doped into the titanium lattice are associated with the dominant 4+ valence oxidation state, which introduces two curved, intermediate bands within the band gap and results in a significant enhancement in photoabsorption and the quantity of photogenerated hydroxyl radicals. Additionally, the high photocatalytic performance of manganese‐doped TiO2 is also attributed to the low oxygen content, owing to the equilibrium fabrication conditions. This work provides an important strategy to control the chemical and defect states of dopants by using an equilibrium fabrication process. 相似文献
Recent advances in direct‐use plasmonic‐metal nanoparticles (NPs) as photocatalysts to drive organic synthesis reactions under visible‐light irradiation have attracted great interest. Plasmonic‐metal NPs are characterized by their strong interaction with visible light through excitation of the localized surface plasmon resonance (LSPR). Herein, we review recent developments in direct photocatalysis using plasmonic‐metal NPs and their applications. We focus on the role played by the LSPR of the metal NPs in catalyzing organic transformations and, more broadly, the role that light irradiation plays in catalyzing the reactions. Through this, the reaction mechanisms that these light‐excited energetic electrons promote will be highlighted. This review will be of particular interest to researchers who are designing and fabricating new plasmonic‐metal NP photocatalysts by identifying important reaction mechanisms that occur through light irradiation. 相似文献
Two hydrophilic conjugated polymers, PmP‐NOH and PmP36F‐NOH, with polar diethanolamine on the side chains and main chain structures of poly(meta‐phenylene) and poly(meta‐phenylene‐alt‐3,6‐fluorene), respectively, are successfully synthesized. The films of PmP‐NOH and PmP36F‐NOH show absorption edges at 340 and 343 nm, respectively. The calculated optical bandgaps of the two polymers are 3.65 and 3.62 eV, respectively, the largest ones so far reported for hydrophilic conjugated polymers. PmP‐NOH and PmP36F‐NOH also possess deep‐lying highest occupied molecular orbital levels of −6.19 and −6.15 eV, respectively. Inserting PmP‐NOH and PmP36F‐NOH as a cathode interlayer in inverted polymer solar cells with a PTB7/PC71BM blend as the active layer, high power conversion efficiencies of 8.58% and 8.33%, respectively, are achieved, demonstrating that the two hydrophilic polymers are excellent interlayers for efficient inverted polymer solar cells.
High molecular weight cyclic poly(ε‐caprolactone)s (cPCLs) with variable ring size are synthesized via light‐induced ring closure of α,ω‐anthracene‐terminated PCL (An‐PCL‐An). The ring size of cPCL is tunable simply by adjusting the polymer concentration from 10 to 100 mg mL−1 in THF. The cycloaddition via the bimolecular cyclization of An‐PC‐An is well characterized by a variety of analyses such as 1H NMR and UV–vis spectroscopies, gel‐permeation chromatography, and differential scanning calorimetry. The reversible dimerization of An induced by heating enables the cyclic PCL to have a switchable “on–off” capability. This novel light‐induced ring‐closure technique can be one of the most powerful candidates for producing various well‐defined cyclic polymers in highly concentrated polymer solution.
Hierarchical semicrystalline block copolymer nanoparticles are produced in a segmented gas‐liquid microfluidic reactor with top‐down control of multiscale structural features, including nanoparticle morphologies, sizes, and internal crystallinities. Control of multiscale structure on disparate length scales by a single control variable (flow rate) enables tailoring of drug delivery nanoparticle function including release rates.
Journal of Solution Chemistry - The interaction between Dy(Ш)/Rutin complexes and bovine serum albumin (BSA) was studied by fluorescence, ultraviolet (UV) absorption, three-dimensional... 相似文献
Kinetics and Catalysis - Using a modified deposition-precipitation method, a series of Au–Mo/ZSM-5 catalysts with different Au loadings were prepared. The XRD, nitrogen adsorption-desorption,... 相似文献