Two new reagents. dimethylammonium chlorochromale adsrbed on alumina and silicagel are describe as convenient reagents for efficient oxidation of a variety of primary and secondaryalcohols. These two reagents are very...Two new reagents. dimethylammonium chlorochromale adsrbed on alumina and silicagel are describe as convenient reagents for efficient oxidation of a variety of primary and secondaryalcohols. These two reagents are very stable and call be safely used for the oxidation of alcoholscontaining double bond.展开更多
Metal halide perovskites have emerged as novel and promising photocatalysts for hydrogen generation.Currently,their stability in water is a vital and urgent research question.In this paper a novel approach to stabiliz...Metal halide perovskites have emerged as novel and promising photocatalysts for hydrogen generation.Currently,their stability in water is a vital and urgent research question.In this paper a novel approach to stabilize a bismuth halide perovskite[(CH_(3))_(2)NH_(2)]_(3)[Bil_(6)](DA_(3)Bil_(6))in water using dimethylammonium iodide(DAI)without the assistance of acids or coatings is reported.The DA3Bil6 powder exhibits good stability in DAI solutions for at least two weeks.The concentration of DAI is found as a critical parameter,where the I^(-)ions play the key role in the stabilization.The stability of DA3Bil6 in water is realized via a surface dissolution-recrystallization process.Stabilized DA3Bil6 demonstrates constant photocatalytic properties for visible light-induced photo-oxidation of I^(-)ions and with PtCI4 as a co-catalyst(Pt-DA_(3)Bil_(6)),photocatalytic H2 evolution with a rate of 5.7μmol·h^(-1)from HI in DAI solution,obtaining an apparent quantum efficiency of 0.83%at 535 nm.This study provides new insights on the stabilization of metal halide perovskites for photocatalysis in aqueous solution.展开更多
A new 3D supramolecular complex,namely dimethylammonium 4,4΄-([2,2΄-bipyrimidine]-5,5΄-diyl)bis(2-hydroxybenzoate)dihydrate,has been synthesized by the reaction of 4,4΄-([2,2΄-bipyrimidine]-5,5΄-diyl)bis(2-hydroxybenz...A new 3D supramolecular complex,namely dimethylammonium 4,4΄-([2,2΄-bipyrimidine]-5,5΄-diyl)bis(2-hydroxybenzoate)dihydrate,has been synthesized by the reaction of 4,4΄-([2,2΄-bipyrimidine]-5,5΄-diyl)bis(2-hydroxybenzoic acid)with aqueous dimethylamine solution and characterized by single-crystal X-ray diffraction,^(1)H NMR spectroscopy and elemental analysis.It belongs to triclinic system,space groupP with a=6.5539(4),b=9.4977(6),c=12.1407(8)Å,α=72.299(6),β=89.160(5),γ=70.797(8)°,V=676.52(8)Å^(3),Z=1,Mr=556.57,µ=0.103 mm^(-1),Dc=1.366 g/cm^(3),F(000)=294,the final R=0.0828 and wR=0.2083 for 1934 observed reflections with I>2σ(I).The 4,4΄-([2,2΄-bipyrimidine]-5,5΄-diyl)bis(2-hydroxybenzoic acid)dianion,dimethylammonium cation,and water molecule are interconnected by O−H∙∙∙O,N−H∙∙∙N,and N−H∙∙∙O hydrogen bonds,forming a two-dimensional(2D)layer.Two adjacent 2D layers are further stacked into a three-dimensional supramolecular structure through O−H∙∙∙O hydrogen bonds.In addition,the luminescent property of this supramolecular complex has also been investigated.展开更多
The effect of radiation on high-charge-density cationic polymer, polydiallyl-dimethyl ammonium chloride (poly-DADMAC), in dilute aqueous solution was investigated. The irradiated samples were characterized in terms of...The effect of radiation on high-charge-density cationic polymer, polydiallyl-dimethyl ammonium chloride (poly-DADMAC), in dilute aqueous solution was investigated. The irradiated samples were characterized in terms of reducedviscosity and electric conductivity. The crosslinking reaction of polyDADMAC chains occurs preferentially in the irradiatedsamples at a concentration of polyDADMAC higher than 1.3 g/100 mL that was induced indirectly by the OH radicals, oneof the radiolysis products of water. In more dilute samples (less than 0.8 g/100 mL) the chain scission of macro radicalsappears to be the main reaction. N_2O atmosphere enhances the crosslinking due to the extra OH radicals produced byreaction between N_2O and e_(aq), another radiolysis products of water. Methanol and some mineral salts such as KCl, KBr inhibit the crosslinking to a certain extent. The mechanism of sensitization and inhibition is discussed in detail.展开更多
钙钛矿前驱体(PbI2和CH3NH3I)分散体系,作为一种新型染料敏化太阳能电池(Dye-sensitized Solar Cells,DSSCs)电解质,光电流和光电压的继续提升是其发展过程中亟待解决的问题.在本工作中,研究发现,通过引入二甲基碘化铵(DMAI)作为钙钛矿...钙钛矿前驱体(PbI2和CH3NH3I)分散体系,作为一种新型染料敏化太阳能电池(Dye-sensitized Solar Cells,DSSCs)电解质,光电流和光电压的继续提升是其发展过程中亟待解决的问题.在本工作中,研究发现,通过引入二甲基碘化铵(DMAI)作为钙钛矿前驱体电解质的高效添加剂,可将光电流密度从12.85 mA·cm-2急剧提升至19.19 mA· cm-2.借助阻抗和塔菲尔曲线分析,发现其光电流的增加与TiO2半导体导带的向上移动对不平衡载流子复合的抑制作用具有一定的相关性.进一步通过叔丁基吡啶的调节作用,可将光电转换效率提高到8.46%,超过了传统的碘电解质.也为染料敏化太阳能电池的研究开辟了新的途径.展开更多
文摘Two new reagents. dimethylammonium chlorochromale adsrbed on alumina and silicagel are describe as convenient reagents for efficient oxidation of a variety of primary and secondaryalcohols. These two reagents are very stable and call be safely used for the oxidation of alcoholscontaining double bond.
基金the Kvantum Institute Em erging Project at the University of Oulu and Academy of Finland ELECTRA-project(No.2430291511).We thank Raija Oilunkaniemi and idarkus Riihimaki for the help with XRD and ATR characterization,respectively.We are grateful to the staff from Centre for Material Analysis(University of Oulu)for the characterization.ELI-ALPS is supported by the European Union and co-flnanced by the European Regional Development Fund(No.GINOP-2.3.6-15-2015-00001).M.U.K.also acknow ledgesfundingfrom PaNOSC Europeanproject.
文摘Metal halide perovskites have emerged as novel and promising photocatalysts for hydrogen generation.Currently,their stability in water is a vital and urgent research question.In this paper a novel approach to stabilize a bismuth halide perovskite[(CH_(3))_(2)NH_(2)]_(3)[Bil_(6)](DA_(3)Bil_(6))in water using dimethylammonium iodide(DAI)without the assistance of acids or coatings is reported.The DA3Bil6 powder exhibits good stability in DAI solutions for at least two weeks.The concentration of DAI is found as a critical parameter,where the I^(-)ions play the key role in the stabilization.The stability of DA3Bil6 in water is realized via a surface dissolution-recrystallization process.Stabilized DA3Bil6 demonstrates constant photocatalytic properties for visible light-induced photo-oxidation of I^(-)ions and with PtCI4 as a co-catalyst(Pt-DA_(3)Bil_(6)),photocatalytic H2 evolution with a rate of 5.7μmol·h^(-1)from HI in DAI solution,obtaining an apparent quantum efficiency of 0.83%at 535 nm.This study provides new insights on the stabilization of metal halide perovskites for photocatalysis in aqueous solution.
基金the National Natural Science Foundation of China(21372112)。
文摘A new 3D supramolecular complex,namely dimethylammonium 4,4΄-([2,2΄-bipyrimidine]-5,5΄-diyl)bis(2-hydroxybenzoate)dihydrate,has been synthesized by the reaction of 4,4΄-([2,2΄-bipyrimidine]-5,5΄-diyl)bis(2-hydroxybenzoic acid)with aqueous dimethylamine solution and characterized by single-crystal X-ray diffraction,^(1)H NMR spectroscopy and elemental analysis.It belongs to triclinic system,space groupP with a=6.5539(4),b=9.4977(6),c=12.1407(8)Å,α=72.299(6),β=89.160(5),γ=70.797(8)°,V=676.52(8)Å^(3),Z=1,Mr=556.57,µ=0.103 mm^(-1),Dc=1.366 g/cm^(3),F(000)=294,the final R=0.0828 and wR=0.2083 for 1934 observed reflections with I>2σ(I).The 4,4΄-([2,2΄-bipyrimidine]-5,5΄-diyl)bis(2-hydroxybenzoic acid)dianion,dimethylammonium cation,and water molecule are interconnected by O−H∙∙∙O,N−H∙∙∙N,and N−H∙∙∙O hydrogen bonds,forming a two-dimensional(2D)layer.Two adjacent 2D layers are further stacked into a three-dimensional supramolecular structure through O−H∙∙∙O hydrogen bonds.In addition,the luminescent property of this supramolecular complex has also been investigated.
文摘The effect of radiation on high-charge-density cationic polymer, polydiallyl-dimethyl ammonium chloride (poly-DADMAC), in dilute aqueous solution was investigated. The irradiated samples were characterized in terms of reducedviscosity and electric conductivity. The crosslinking reaction of polyDADMAC chains occurs preferentially in the irradiatedsamples at a concentration of polyDADMAC higher than 1.3 g/100 mL that was induced indirectly by the OH radicals, oneof the radiolysis products of water. In more dilute samples (less than 0.8 g/100 mL) the chain scission of macro radicalsappears to be the main reaction. N_2O atmosphere enhances the crosslinking due to the extra OH radicals produced byreaction between N_2O and e_(aq), another radiolysis products of water. Methanol and some mineral salts such as KCl, KBr inhibit the crosslinking to a certain extent. The mechanism of sensitization and inhibition is discussed in detail.
