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Single-Site Molybdenum Catalyst for the Synthesis of Fumarate
No full textThe catalysts with well-defined mononuclear active sites are expected to develop more active catalytic systems for the key chemical transformations. But the rational design of catalyst with stable mononuclear Mo site is still a crucial challenge because of its oligomerization tendency under reaction condition. Herein, Molybdenum catalyst (Mo-8-HQ) with single Mo sites was designed via the pyridine nitrogen and oxygen in hydroxyl of 8-hydroxyquinoline coordinated with Mo atom. The crystal catalyst was stabilized by pi-pi stacking interaction and hydrogen bonds to form isolated Mo specie. The single-site molybdenum catalyst exhibited excellent catalytic performance in didehydroxylation reactions with high selectively of dibutyl fumarate (86 %) product at mild reaction condition. Deuterium isotopic studies demonstrated that the mechanism feature of didehydroxylation reaction catalyzed by Mo-8-HQ was through concerted cleavage of two C-O bonds process, which could be accelerated by single-site molybdenum catalysts with electron-rich Mo centers
National Science and Technology Major Project of the Ministry of Science and Technology of China[2017ZX05036001]
No full textTransformational Technologies for Clean Energy and Demonstration, Strategic Priority Research Program of the CAS[XDA21060400]
No full textTwo-state diabatic potential energy surfaces of ClH2 based on nonadiabatic couplings with neural networks
No full textA general neural network (NN)-fitting procedure based on nonadiabatic couplings is proposed to generate coupled two-state diabatic potential energy surfaces (PESs) with conical intersections. The elements of the diabatic potential energy matrix (DPEM) can be obtained directly from a combination of the NN outputs in principle. Instead, to achieve higher accuracy, the adiabatic-to-diabatic transformation (ADT) angle (mixing angle) for each geometry is first solved from the NN outputs, followed by individual NN fittings of the three terms of the DPEM, which are calculated from the ab initio adiabatic energies and solved mixing angles. The procedure is applied to construct a new set of two-state diabatic potential energy surfaces of ClH2. The ab initio data including adiabatic energies and derivative couplings are well reproduced. Furthermore, the current diabatization procedure can describe well the vicinity of conical intersections in high potential energy regions, which are located in the T-shaped (C-2v) structure of Cl-H-2. The diabatic quantum dynamical results on diabatic PESs show large differences as compared with the adiabatic results in high collision energy regions, suggesting the significance of nonadiabatic processes in conical intersection regions at high energies
