α, α＇-Benzylidene bis（4-hydroxycoumarin） derivatives were readily prepared in a few minutes with good yields through the reaction of an aromatic aldehyde and 4-hydroxycoumarin in aqueous media in the presence of ...α, α＇-Benzylidene bis（4-hydroxycoumarin） derivatives were readily prepared in a few minutes with good yields through the reaction of an aromatic aldehyde and 4-hydroxycoumarin in aqueous media in the presence of catalytic tris（hydrogensulfato） boron [B（HSO_4）_3].展开更多
Poly(silphenylene-siloxane)s had been synthesized through dehydrocarbon polycondensation of 1,4- bis(dimethylsilyl)benzene(BDSB)and dialkoxysilane.The polymer composition and structure was characterized by ^(29)Si-NMR...Poly(silphenylene-siloxane)s had been synthesized through dehydrocarbon polycondensation of 1,4- bis(dimethylsilyl)benzene(BDSB)and dialkoxysilane.The polymer composition and structure was characterized by ^(29)Si-NMR.The influence of temperature,B(C_6F_5)_3 concentration and monomer structure on the composition and the microstructure of the copolymers were investigated.It shows that elevating reaction temperature or using substrate (R O)_2R_2R_1Si with bulk organic group of R_1 or R_2 augments the run numb...展开更多
近年来,受限路易斯酸碱对(FLPs:Frustrated Lewis Pairs)在小分子的活化以及在催化还原等方面所表现出的独特反应特性,使得有关FLPs化学的研究受到了国内外广泛的关注.设计了一种新型的FLPs催化体系,该体系以三(五氟苯基)硼(BCF)为路易...近年来,受限路易斯酸碱对(FLPs:Frustrated Lewis Pairs)在小分子的活化以及在催化还原等方面所表现出的独特反应特性,使得有关FLPs化学的研究受到了国内外广泛的关注.设计了一种新型的FLPs催化体系,该体系以三(五氟苯基)硼(BCF)为路易斯酸,以多种不同取代的有机胺盐酸盐替代常规FLPs中的路易斯碱有机胺.发现利用该体系与氢化硅烷反应,不仅可以高产率地制备分离得到相应的伯、仲、叔硼氢化胺盐;而且还可以这一体系作为催化剂,以氢化硅烷作为还原剂,在常温常压下可高选择性地部分或彻底还原大部分含羰基官能团醛酮等有机化合物.由BCF/2,2,6,6-四甲基哌啶(TMP)盐酸盐组成的催化体系在对CO2催化还原为甲烷的反应中,亦较相应的BCF/TMP体系显示更高的活性.还通过核磁共振详细地对比研究了原料有机胺盐酸盐、中间体氯代硼胺盐以及产物氢化硼胺盐中,胺基氮上质子的核磁共振谱信息,发现不仅胺基上取代基的位阻效应会影响到具有电四极矩性的14N磁性核的弛豫效应,而且阴离子基团的配位强弱对胺基氮上质子的化学位移也会产生较大的影响.展开更多
We report the synthesis of covalent organic framework(COF)crystals with organic Lewis acid instead of the conventional use of Br?nsted acid or inorganic Lewis acid.Specifically,tris(pentafluorophenyl)borane was applie...We report the synthesis of covalent organic framework(COF)crystals with organic Lewis acid instead of the conventional use of Br?nsted acid or inorganic Lewis acid.Specifically,tris(pentafluorophenyl)borane was applied for the growth of seven imine COFs:TAPB-PDA-,TAPB-2,5-DMTA-,TAPB-2,3-DMTA-,TAPT-PDA-,TAPT-2,5-DMTA-,TAPT-2,3-DMTA-COF with hcb topology and varied in functional groups,as well as a new one,COF-820,with sql topology.All these COFs were obtained at room temperature.Their high crystallinity and porosity demonstrate the versatility of the organic Lewis acid as a catalyst.Bulky organic Lewis acid was found critical for the production of COF-820,while its absence resulted in the formation of a different COF,4PE-1P-COF,with kgm topology using the same building blocks.Such steric effect,typical for organic catalysts,provides a new way to regulate the topology of COFs and their future design.展开更多
文摘α, α＇-Benzylidene bis（4-hydroxycoumarin） derivatives were readily prepared in a few minutes with good yields through the reaction of an aromatic aldehyde and 4-hydroxycoumarin in aqueous media in the presence of catalytic tris（hydrogensulfato） boron [B（HSO_4）_3].
文摘Poly(silphenylene-siloxane)s had been synthesized through dehydrocarbon polycondensation of 1,4- bis(dimethylsilyl)benzene(BDSB)and dialkoxysilane.The polymer composition and structure was characterized by ^(29)Si-NMR.The influence of temperature,B(C_6F_5)_3 concentration and monomer structure on the composition and the microstructure of the copolymers were investigated.It shows that elevating reaction temperature or using substrate (R O)_2R_2R_1Si with bulk organic group of R_1 or R_2 augments the run numb...
文摘近年来,受限路易斯酸碱对(FLPs:Frustrated Lewis Pairs)在小分子的活化以及在催化还原等方面所表现出的独特反应特性,使得有关FLPs化学的研究受到了国内外广泛的关注.设计了一种新型的FLPs催化体系,该体系以三(五氟苯基)硼(BCF)为路易斯酸,以多种不同取代的有机胺盐酸盐替代常规FLPs中的路易斯碱有机胺.发现利用该体系与氢化硅烷反应,不仅可以高产率地制备分离得到相应的伯、仲、叔硼氢化胺盐;而且还可以这一体系作为催化剂,以氢化硅烷作为还原剂,在常温常压下可高选择性地部分或彻底还原大部分含羰基官能团醛酮等有机化合物.由BCF/2,2,6,6-四甲基哌啶(TMP)盐酸盐组成的催化体系在对CO2催化还原为甲烷的反应中,亦较相应的BCF/TMP体系显示更高的活性.还通过核磁共振详细地对比研究了原料有机胺盐酸盐、中间体氯代硼胺盐以及产物氢化硼胺盐中,胺基氮上质子的核磁共振谱信息,发现不仅胺基上取代基的位阻效应会影响到具有电四极矩性的14N磁性核的弛豫效应,而且阴离子基团的配位强弱对胺基氮上质子的化学位移也会产生较大的影响.
基金supported by the National Natural Science Foundation of China(22025106,21971199)the National Key Research and Development Project(2018YFA0704000)the Innovation Team of Wuhan University(2042017kf0232)。
文摘We report the synthesis of covalent organic framework(COF)crystals with organic Lewis acid instead of the conventional use of Br?nsted acid or inorganic Lewis acid.Specifically,tris(pentafluorophenyl)borane was applied for the growth of seven imine COFs:TAPB-PDA-,TAPB-2,5-DMTA-,TAPB-2,3-DMTA-,TAPT-PDA-,TAPT-2,5-DMTA-,TAPT-2,3-DMTA-COF with hcb topology and varied in functional groups,as well as a new one,COF-820,with sql topology.All these COFs were obtained at room temperature.Their high crystallinity and porosity demonstrate the versatility of the organic Lewis acid as a catalyst.Bulky organic Lewis acid was found critical for the production of COF-820,while its absence resulted in the formation of a different COF,4PE-1P-COF,with kgm topology using the same building blocks.Such steric effect,typical for organic catalysts,provides a new way to regulate the topology of COFs and their future design.
