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Saikat Banerjee Waqas Rasheed Ruixi Fan Dr. Apparao Draksharapu Dr. Williamson N. Oloo Prof. Dr. Yisong Guo Prof. Dr. Lawrence Que Jr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(41):9608-9613
The [FeIV(O)(Me3NTB)]2+ (Me3NTB=tris[(1-methyl-benzimidazol-2-yl)methyl]amine) complex 1 has been shown by Mössbauer spectroscopy to have an S=1 ground state at 4 K, but is proposed to become an S=2 trigonal-bipyramidal species at higher temperatures based on a DFT model to rationalize its very high C−H bond-cleavage reactivity. In this work, 1H NMR spectroscopy was used to determine that 1 does not have C3-symmetry in solution and is not an S=2 species. Our results show that 1 is unique among nonheme FeIV=O complexes in retaining its S=1 spin state and high reactivity at 193 K, providing evidence that S=1 FeIV=O complexes can be as reactive as their S=2 counterparts. This result emphasizes the need to identify factors besides the ground spin state of the FeIV=O center to rationalize nonheme oxoiron(IV) reactivity. 相似文献
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Three-dimensional fluorescence spectroscopy coupled with parallel factor analysis and neural network was applied to the year discrimination of mild aroma Chinese liquors. The excitation-emission fluorescence matrices (EEMs) of 120 samples with various years were measured by FLS920 fluorescence spectrometer. The trilinear decomposition of the data array was performed and the loading scores of and the excitation-emission profiles of four components were also obtained. The scores were employed as the inputs of the BP neural networks and the PARAFAC-BP identification model was constructed. 10 samples were collected from 10, 20 and 30 years of liquors respectively, and 30 samples were selected as the test sets. The remaining 90 samples were used as the training sets to build the training model. The year prediction of unknown samples was also carried out, and the prediction accuracy was 90%, 100% and 100%, respectively. Meanwhile, the discrimination analysis method and the multi way partial least squares discriminant analysis were compared, namely PARAFAC-BP and NPLS-DA. The results indicated that parallel factor combined with the neural network (PARAFAC-BP) has higher prediction accuracy. The proposed method can effectively extract the spectral characteristics, and also reduce the dimension of the input variables of neural network. A good year discrimination result was finally achieved. 相似文献
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Transition metal phosphides (TMPs) are prospective anode materials for lithium-ion batteries (LIBs) due to their high theoretical capacities and low redox voltages. Herein, we report a template directing method to develop a tube-sheath hybrid composing of cobalt phosphide particles encapsulated in metal organic frameworks (MOFs) derived N-doped carbon sheaths (CoxP@NC). The utilization of directing template leads to a homogenous distribution of the subsequently formed cobalt phosphide particles, restrains the aggregation of cobalt phosphides, and thus results in the superb rate capability and cyclability. Contributable to the integrated merits of the interior downsized cobalt phosphide particles and the outer ZIF-67 derived porous carbon sheath, the volume expansion during cycling is effectively suppressed. The CoxP@NC hybrid shows superb electrochemical performance as anode material for LIB, with good reversible capacity of 928 mAh·g?1 after 100 cycles at 0.1 A g?1, and high stability of 526 mAh·g?1 after 600 cycles at 1.0 A g?1. This work provides a route for rational design of MOF derived carbon-based anode material for LIB, which could also be applied as a promising platform in diverse field. 相似文献
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Azobenzene-containing TiO2/γ-glycidoxypropyltrimethoxysilane and methyltrimethoxysilane hybrid films are prepared by combining a low temperature sol–gel
process and a spin-coating technique. The trans–cis isomerization of azobenzene small molecules inside organic–inorganic hybrid films is induced by a photoirradiation under
UV light. It is noted that below a baking temperature of 150 °C is necessary for the hybrid films in optical storage or optical
switching applications. The change of the refractive index and thickness of the hybrid films with real-time heating temperature
are observed by using a prism coupling technique. The structural properties of the hybrid films are also characterized and
investigated by thermal gravimetric analysis, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy.
The results indicate that the as-prepared hybrid films might allow directly integrating the optical storage or optical switching
devices with the waveguide devices on the same chip. 相似文献
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