Bingjie Ding

Bio: Bingjie Ding is an academic researcher from East China University of Science and Technology. The author has contributed to research in topics: Ionic liquid & Catalysis. The author has an hindex of 2, co-authored 7 publications receiving 18 citations.

Ionic Liquid Stabilized Niobium Oxoclusters Catalyzing Oxidation of Sulfides with Exceptional Activity

Abstract: We present here a new class of niobium oxoclusters that are stabilized effectively by carboxylate ionic liquids. These functionalized ILs are designated as [TBA][LA], [TBA][PA], and [TBA][HPA] in this work, in which TBA represents tetrabutylammonium and LA, PA, and HPA refer to lactate, propionate, 3-hydroxypropionate anions, respectively. The as-synthesized Nb oxoclusters have been characterized by use of elemental analysis, NMR, IR, XRD, TGA, HRTEM. It was found that [TBA][LA]-stabilized Nb oxoclusters (Nb-OC@[TBA][LA]) are uniformly dispersed with an average particle size of 2-3 nm and afforded exceptionally high catalytic activity for the selective oxidation of various thioethers. The turnover number with Nb-OC@[TBA][LA] catalyst was over 56 000 at catalyst loading as low as 0.0033 mol % (1 ppm). Meantime, the catalyst also showed the high activity for the epoxidation of olefins and allylic alcohols by using only 0.065 mol % of catalyst (50 ppm). The characterization of 93 Nb NMR spectra revealed that the Nb oxoclusters underwent structural transformation in the presence of H2 O2 but regenerated to their initial state at the end of the reaction. In particular, the highly dispersed Nb oxoclusters can absorb a large amount of polar organic solvents and thus were swollen greatly, which exhibited "pseudo" liquid phase behavior, and enabled the substrate molecules to be highly accessible to the catalytic center of Nb oxocluster units.

Role of Organic Fluoride Salts in Stabilizing Niobium Oxo-Clusters Catalyzing Epoxidation.

Abstract: We present here that easily available organic salts can stabilize/modify niobium (Nb) oxo-clusters. The as-synthesized Nb oxo-clusters have been characterized by various methods. These Nb oxo-clusters were catalytically active for the epoxidation of allylic alcohols and olefins with H2O2 as an oxidant. Notably, Nb-OC@TBAF-0.5 appeared as highly dispersed nanosized particles and showed the highest catalytic activity, which can be attributed to the following reasons on the basis of characterization. First, the strong coordination of fluorine ions with Nb sites and the steric protection with bulky organic cations led to high stabilization and dispersion of the oxo-clusters in the course of the reaction. Second, a hydrogen-bond interaction between the coordinated fluorine atom and the -OH group of allylic alcohol favored the epoxidation reaction. Third, the electron density of Nb sites decreased due to the strong electron-withdrawing ability of F- adjacent to Nb sites, thus promoting the electrophilic oxygen transfer to the C═C bond.

Water-soluble niobium peroxo-complexes as precursors for the preparation of Nb-based oxide catalysts (poster)

Abstract: In the frame of research aimed at developing new synthetic procedures of multimetallic Nb-based catalysts, peroxo complexes of niobium(V) of general formula A I 3 [Nb(O 2 ) 4 ] and A I 3 [Nb(O 2 ) x (H y L)]. n H 2 O (A I : NH 4 +, CN 3 H 6 + (gu); L: oxalate, tartrate, citrate) have been prepared and characterized on the basis of elemental and thermal analysis, FTIR and 13 C-NMR spectra. The crystal structure of (gu) 3 [Nb(O 2 ) 4 ] and (gu) 3 [Nb(O 2 ) 2 (C 2 O 4 ) 2 ].2H 2 O have been determined. The application of the obtained Nb complexes as precursors for the preparation of silica-supported Nb-Mo-O catalysts has been demonstrated. Combining Nb peroxo-carboxylato compounds with analogous Mo(VI) compounds in a silica-impregnation method carried out in aqueous medium leads to the formation of the supported Nb 2 Mo 3 O 14 phase.

Molecular, supramolecular and solution structures ofperoxovanadium complexes with ON and O3N donor set ligands: twonew types of cationic-anionic peroxovanadium(V)peroxovanadates(V)

Abstract: The complexes, [VO(O-2)(pa)(2)] ClO4 . 3H(2)O ( 1), [VO(O-2)(pa)(2)][ VO(O-2)(2)(pa)] . 3H(2)O (2), [VO(O-2)(pa)(2)][VO(O-2)( ada)] . 2H(2)O ( 3) and [VO(O-2)(pa)(pca)] . H2O ( 4) [pa = picolinamide, ada = carbamoylmethyliminodiacetate( 2-) and pca = 2- pyrazinecarboxylate(1-)], were synthesized. 2 and 3 are new types of peroxovanadium complexes: monoperoxovanadium diperoxovanadate ( 2) and monoperoxovanadium monoperoxovanadate ( 3). The complexes were characterized by chemical analysis and IR spectroscopy, and 1, 3 and 4 also by X-ray analysis. The structure of 1 is disordered, with alternating positions of the oxo and peroxo ligands. The peroxo oxygen atoms, O-p, in 1 are involved in weak hydrogen bonds with water molecules and close intramolecular C - H...O-p bonds [d(H...O-p) similar to 2.0 Angstrom]. The supramolecular structure of 1 is formed by a network of hydrogen bonds and strong attractive intermolecular pi - pi interactions between the pyridine rings. The supramolecular architecture in 4 is constructed by (N, O) - H...O hydrogen bonds between the neutral complex molecules and water of crystallization. The peroxo oxygen atoms in 4 form intramolecular C - H...O-p bonds [d( H...O-p) = 2.303 Angstrom]. The pa and pca ligands are ON coordinated via the oxygen atoms of the C(NH2)=O and COO- groups, respectively, and nitrogen atoms of the heterocyclic rings, and ada as a tetradentate O3N ligand. The thermal analysis of 4 showed that the loss of water of crystallization and the active oxygen release (T-min/degreesC 82, T-max/degreesC 165) are, under given conditions, individual processes separated by the temperature interval 90 - 132 degreesC. The solution structures and stability were studied by UV-VIS and V-51 NMR spectroscopies.

In situ construction of phenanthroline-based cationic radical porous hybrid polymers for metal-free heterogeneous catalysis

Abstract: Rational design of multifunctional radical porous polymers with redox activity for targeted metal-free heterogeneous catalysis is an important research topic. In this work, we reported a new class of phenanthroline-based cationic radical porous hybrid polymers (Phen˙+-PHPs), which were constructed from the Heck reaction between a newly designed dibromo-substituted phenanthroline ionic monomer (iDBPhen) and a rigid building block, octavinylsilsesquioxane (VPOSS). For the first time, the stable phenanthroline-based radical cation was unexpectedly discovered in these polyhedral oligomeric silsesquioxane (POSS)-based porous hybrid polymers, probably undergoing in situ reduction of the dicationic monomer iDBPhen during the alkaline reagent K2CO3-involved Heck reaction. The radical characters of the typical porous polymers Phen˙+-PHP-2 and Phen˙+-PHP-2Br were confirmed from the electron paramagnetic resonance (EPR) spectra and X-ray photoelectron spectra (XPS). The chemical structures and porous geometry were fully characterized by a series of advanced technologies. Surprisingly, the metal-free cationic radical polymer Phen˙+-PHP-2 exhibited high heterogeneous catalytic efficiency in the H2O2-mediated selective oxidation of various sulfides to sulfoxides with high yields under mild conditions, owing to the electron-accepting and redox ability of Phen-based dications and radical cations. Moreover, the extended sample Phen˙+-PHP-2Br prepared by post-treatment of Phen˙+-PHP-2 with aqueous HBr was also employed as a metal-free efficient heterogeneous catalyst in the conversion of CO2 with epoxides into cyclic carbonates under atmospheric pressure and low temperatures. The remarkable catalytic performance in CO2 conversion should be assigned to the synergistic catalysis of POSS-derived Si–OH groups and nucleophilic Br− anions and N active atom-involved Phen cationic radical moieties within Phen˙+-PHP-2Br. These two catalysts can be facilely recovered and reused, also with stable recyclability in the above catalytic reaction systems, achieving the heterogeneous catalytic demands for multipurpose reactions.