Huanwang Jing

Bifunctional Chiral Catalyst for the Synthesis of Chiral Cyclic Carbonates from Carbon Dioxide and Epoxides

Bifunctional chiral catalysts incorporating the N,N′‐bis(salicylidene)cyclohexenediaminato (salen) ligand and a quaternary onium salt within one metal complex were synthesized and developed for the catalytic kinetic resolution of racemic epoxides with carbon dioxide to generate chiral cyclic carbonates in high yield and with moderate enantioselectivity. These new catalysts also have a great advantage as they can be recycled without any obvious loss of activity and enantioselectivity.

Chiral ionic liquids improved the asymmetric cycloaddition of CO2 to epoxides

The new catalyst system of chiral SalenCo(OAc)/chiral ionic liquid was developed to catalyze the asymmetric cycloaddition reaction of CO2 and epoxides yielding the chiral cyclic carbonates. The synergistic effect between them is discussed.

Carbon Dioxide Fixation by Cycloaddition with Epoxides, Catalyzed by Biomimetic Metalloporphyrins

Several biomimetic metalloporphyrin complexes (M(TPP)XY; in which TPP=meso‐porphyrin; M=MgII, AlIII, SnII, or SnIV; X=OAc, F, Cl, Br, I, OTf, or none; and Y=Cl, Br, I, OTf, or none) were prepared, characterized, and used effectively in the “green” synthesis of cyclic carbonates from epoxides and CO2. The catalytic systems of Mg(TPP)/tetrabutylammonium iodide and Al(TPP)Cl/phenyltrimethyl ammonium tribromide can initiate the cycloaddition of epoxides and CO2 at room temperature to generating cyclic carbonates in excellent yield. Chlorophyll A is shown to induce enantioselectivity of racemic propylene oxide. All reactions displayed excellent selectivity to cyclic carbonate without polycarbonate and other by‐products. Chloropropylene carbonate is shown to be obtained under CO2 bubbling conditions catalyzed by Al(TPP)Cl/phenyltrimethylammonium tribromide. The catalytic order of activity for biomimetic metalloporphyrins is AlIII>MgII>SnIV>SnII. These phenomena are explained with respect to the Lewis acidity of metal center in metalloporphyrins.

Cycloaddition of epoxides and CO2 catalyzed by bisimidazole-functionalized porphyrin cobalt(III) complexes

A series of innovative bisimidazole-functionalized porphyrin cobalt(III) complexes have been devised, synthesized and characterized using NMR, MS and elemental analysis. These homogeneous catalysts were applied to the cycloaddition of epoxides and carbon dioxide without organic solvent and co-catalyst. It was found that the performance of the catalysts deeply relies on their structural features. The alkoxyl chain length of the linkage and the imidazole position relative to the phenyl rings of porphyrin evidently affects the catalyst activities. [5,15-Di(3-((8-imidazolyloctyl)oxy)phenyl)porphyrin] cobalt(III) chloride (J-m8) and [5,15-di(2-((6-imidazolylhexyl)oxy)phenyl)porphyrin] cobalt(III) chloride (J-o6) demonstrated excellent activity under optimal reaction conditions. Synchronously, a preliminary kinetic investigation of this reaction was carried out using three catalysts and illustrated the activation energies of cyclic carbonate formation. Furthermore, a tri-synergistic catalytic mechanism has been carefully proposed in light of the features of the new catalysts and experimental results.

New magnetic nanocomposites of ZrO2–Al2O3–Fe3O4 as green solid acid catalysts in organic reactions

A series of magnetic solid acid nano-catalysts were designed and prepared through a facile co-precipitate approach. The original nanocomposites ZrO2–Al2O3–Fe3O4 were characterized by means of ICP-AES, BET, XRD, TEM, HRTEM, VSM, FT-IR, NH3-TPD and TG. Their catalytic behaviours were investigated via esterification, the synthesis of bis-indolylmethanes, Hantzsch reaction, Biginelli reaction and Pechmann reaction. In all of these organic reactions, the corresponding products were obtained in moderate to excellent yields. The optimal catalyst was ZAF-16/16, which retained catalytic activity after several recycles.

Salicylic Acid As a Tridentate Anchoring Group for azo-Bridged Zinc Porphyrin in Dye-Sensitized Solar Cells

Two series dyes of azo-bridged zinc porphyrins have been devised, synthesized, and performed in dye-sensitized solar cells, in which salicylic acids and azo groups were introduced as a new anchoring group and π-conjugated bridge via a simple synthetic procedure. The representation of the new dyes has been investigated by optical, photovoltaic, and electrochemical means. The photoelectric conversion efficiency of their DSSC devices has been improved compared with other DSSC devices sensitized by symmetrical porphyrin dyes. The results revealed that tridentate binding modes between salicylic acid and TiO2 nanoparticles could enhance the efficiency of electron injection. The binding modes between salicylic acid and TiO2 nanoparticles may play a crucial role in the photovoltaic performance of DSSCs.

Bifunctional Metalloporphyrins-Catalyzed Coupling Reaction of Epoxides and CO2 to Cyclic Carbonates

Abstract New catalysts of water soluble bifunctional metalloporphyrins M(TTMAPP)I 4 (X) (M = Co, Fe, Mn, and Cr; X = OAc, CF 3 COO, CCl 3 COO, OTs, Cl, Br, and I) were synthesized and used to catalyze the synthesis of cyclic carbonate through the coupling reaction of terminal epoxides and CO 2 . The effects of reaction temperature, various metals as the Lewis acidic center, counterions, and recycling of the catalysts were studied. 5,10,15,20- Tetra -( p - N , N , N -trimethylphenyl ammonium iodide)porphyrinium cobalt(III) acetate [Co(III)(TTMAPP) I 4 (OAc)] was efficient in the coupling reaction of various terminal epoxides and CO 2 at 353 K under 667 kPa of CO 2 pressure without solvent and molar ratio of epoxide:catalyst = 1000. It gave a propylene carbonate yield of 95.4% within 5 h. At 298 K in the presence of 1 ml methanol with the molar ratio of epoxide:catalyst = 2000, it gave a propylene carbonate yield of 19.4% within 24 h. The catalyst could be recovered with diethyl ether and reused five times without significant loss of catalytic activity.

Aerobic oxidative carboxylation of olefins with metalloporphyrin catalysts

Dioxo(tetraphenylporphyrinato)ruthenium(VI) and quaternary onium salt were successfully developed as catalysts to initiate a three component reaction of olefin, O2, and CO2 at ambient temperature under low pressure. The reaction can be carried out under solvent-free or solvent conditions. Styrene carbonate was obtained in 76% yield with 100% selectivity using 4 mol% of catalyst under optimized conditions.

Aza-crown ether complex cation ionic liquids: preparation and applications in organic reactions.

Aza-crown ether complex cation ionic liquids (aCECILs) were devised, fabricated, and characterized by using NMR spectroscopy, MS, thermogravimetric differential thermal analysis (TG-DTA), elemental analysis and physical properties. These new and room-temperature ILs were utilized as catalysts in various organic reactions, such as the cycloaddition reaction of CO2 to epoxides, esterification of acetic acid and alcohols, the condensation reaction of aniline and propylene carbonate, and Friedel-Crafts alkylation of indole with aldehydes were investigated carefully. In these reactions, the ionic liquid exhibited cooperative catalytic activity between the anion and cation. In addition, the aza-[18-C-6HK][HSO4]2 was the best acidic catalyst in the reactions of esterification and Friedel-Crafts alkylation under mild reaction conditions.

Strategy to improve photovoltaic performance of DSSC sensitized by zinc prophyrin using salicylic acid as a tridentate anchoring group.

Three new zinc porphyrin dyes attached to ethynyl benzoic acid as an electron transmission and anchoring group have been designed, synthesized, and well-characterized. The performances of their sensitized solar cells have been investigated by optical, photovoltaic, and electrochemical methods. The photoelectric conversion efficiency of the solar cells sensitized by the dye with salicylic acid as an anchoring group demonstrated obvious enhancement when compared with that sensitized by the dye with carboxylic acid as an anchoring group. The density functional theory calculations and the electrochemical impedance spectroscopies revealed that tridentate binding modes could increase the efficiency of electron injection from dyes to the TiO2 nanoparticles by more electron pathways.