钙长石中镓置换骨架铝对结构和Eu~(2+)发光特性的影响

采用高温固相法在弱还原气氛下制备了Ca0.955Al2-xGaxSi2O8∶Eu2+(x=0～1.0)系列荧光粉,研究了Ga3+置换Al3+对晶体结构和光谱特性的影响。Ga3+以类质同相替代CaAl2Si2O8晶格中的Al3+形成连续固溶体,晶胞参数a,b,c和晶胞体积V随Ga3+置换量呈线性增大;晶面夹角α,β和γ随Ga3+置换量的增加呈线性递减。荧光激发谱为宽带,位于230～420 nm,可拟合成4个峰,表观峰值位于352 nm;随着Ga3+置换量的增加,半高宽从112 nm减小到98 nm。发射光谱位于375～560 nm,可由421和457 nm两峰拟合而成,表观峰值位于425 nm,随着Ga3+置换量的增加,两拟合峰均线性红移,且拟合峰强度比呈线性递减。     

白光LED用Sr_(0.955)Al_2Si_(2-x)Ti_xO_8∶Eu~(2+)荧光粉的晶体结构和光谱特性

由高温固相反应制得Sr0.955Al2Si2-xTixO8∶Eu2+(x=0~1.0)系列试样,研究了Ti4+置换Si4+对其晶体结构和光谱特性的影响。Ti4+以类质同相替代Si4+进入基质晶格中,形成了连续固溶体,其晶胞参数a,b,c,β和晶胞体积V随Ti4+置换量呈线性递增。Ti4+置换Si4+对晶胞参数c的影响显著,b其次,a最小。荧光激发谱为宽带,位于230~400nm,由267nm、305nm、350nm和375nm4个峰拟合成,表观峰值位于351nm;随着Ti4+置换量的增加,半高宽(FWHM)从105nm减小到93nm。发射光谱位于380~600nm,表观峰值位于407nm,可由406nm和441nm两峰拟合而成并且随Ti4+置换量增加线性红移,Ti4+进入晶格对长波长发射中心影响较少;Ti4+置换量为1.0时,表观发射峰位从407nm红移至417nm;利用试样荧光光谱和VanUitert经验公式,得出SrAl2Si2O8∶Eu2+中Sr2+的配位数为9。随着Ti4+置换量Si4+进入基质晶格,造成Eu-O距离变小,使得Eu2+所处的晶体场强度增强,发光中心Eu2+的5d能级分裂增大,造成Eu2+最低发射能级重心下移,两拟合谱峰峰位均呈线性红移。     

Sr~(2+(置换对Eu~(2+)掺杂钙长石晶体结构和光谱特性的影响

采用高温固相法在弱还原气氛下制备了Ca0.955-xSrxAl2Si2O8:Eu2+(x=0~0.9)系列荧光粉,研究了Sr2+置换Ca2+对晶体结构和光谱特性的影响。Sr2+进入CaAl2Si2O8晶格与Ca2+发生类质同相替代形成连续固溶体,物相从CaAl2Si2O8相(Triclinic,P1)逐渐转换为SrAl2Si2O8相(Monoclinic,I2/c),晶胞参数a,b,c和晶胞体积都随Sr2+置换量呈线性增加,α,β和γ在置换量为0.1~0.7区间缓慢减小,超过0.7后呈线性急剧减小。位于250~410 nm区间的宽带激发光谱由4个激发峰构成,表观峰值位于356 nm。Eu2+占据两种格位形成两个发光中心,分别产生430和468 nm发射,宽带发射光谱位于390~550 nm区间,呈现近白色发光。控制Sr2+含量可使表观发射峰位置在408~434 nm之间移动,强度随Sr2+含量增加而增强。     

Sr_(0.955)Al_(2-x)B_xSi_2O_8∶0.025Eu~(2+)荧光粉的制备、晶体结构及发光性能（英文）

通过高温固相反应在弱还原气氛下制备了Sr_(0.955)Al_(2-x)B_xSi_2O_8∶0.025Eu~(2+)(x=0～0.9)一系列荧光粉,研究了B(Ⅲ)取代基质晶格中的Al(Ⅲ)对荧光粉晶体结构和Eu~(2+)发光性能的影响。B(Ⅲ)以类质同相取代基质晶格中Al(Ⅲ),形成了连续固溶体。随着B(Ⅲ)取代量的增加,荧光粉的晶胞参数(a、b、c)和晶胞体积(V)呈线性递减,而晶胞参数(β)呈线性递增。荧光粉的激发光谱为位于225～400nm的宽峰,表观峰值位于350 nm,激发峰的半高宽(FWHM)随着B(Ⅲ)取代量的增加,从90 nm减小到102 nm。发射光谱位于370～600 nm的宽峰,可拟合为409和447 nm两个峰,表观峰值位于409 nm。随着B(Ⅲ)取代量的增加,2个拟合峰位均出现蓝移且2个峰强度比呈线性递减。根据试样荧光光谱,通过Van Uitert经验公式计算得出SrAl_2Si_2O_8∶Eu~(2+)中Sr~(2+)的配位数为9。随着B(Ⅲ)取代Al(Ⅲ)进入基质晶格,造成发光中心Eu与配体O距离增加,使得Eu~(2+)所处的晶体场强度减小,发光中心Eu~(2+)的5d能级分裂减小,造成Eu~(2+)最低发射能级重心上移,2个拟合谱峰峰位均呈线性蓝移。     

超细Eu~(2+)掺杂β-Sialon荧光粉的合成及表征

以SiO2,A lC l3.6H2O,Eu(NO3)3、氨水为原料,用溶胶凝胶法制备了前驱物通过碳热还原氮化法(CRN)获得了Eu2+掺杂S i3A l3O3N5(β-S ialon)荧光发光材料。应用X射线衍射(XRD)仪、扫描电子显微镜(SEM)、荧光分光光度计研究了Eu2+掺杂S i3A l3O3N5(-βS ialon)荧光粉物相、形貌及发光性能。在0.45 L.m in-1N2流条件下1380℃保温6 h得到较纯棒状形貌的S i3A l3O3N5(β-S ialon)相。Eu2+掺杂S i3A l3O3N5(β-S ialon)在紫外光部分具有强烈的吸收,其激发光谱的峰值波长为~280 nm,发射光谱的峰值波长为~419 nm,其对应于Eu2+离子4 f65d→4 f7跃迁。     

(Ca,Me)La4Si3O13:Eu3+(Me=Sr,Ba)荧光粉的结构和发光特性

采用高温固相法制备了(Ca,Me)La4Si3O13∶Eu3+(Me=Sr,Ba)系列红色荧光体,考察了Eu3+掺杂浓度和Sr2+,Ba2+置换对荧光体结构和发光特性的影响。Eu3+最佳掺杂浓度为nEu3+∶nLa3+=1∶7,5D0-7F2与5D0-7F1跃迁发射强度比为2.55。Eu3+掺杂使晶胞参数a和c呈线性变小,对c的影响大于a,使a/c比增大。Sr2+和Ba2+分别置换基质中的Ca2+可以形成完全固溶体,晶胞参数随Sr2+或Ba2+的置换量增加呈线性增大,使a/c比减小。各发射峰强度在Sr2+置换量为0.4 mol时出现极大值,但随Ba2+置换量的增加而不断增强,全置换后荧光强度最大。荧光体的色坐标为(0.638 5,0.353 0)。     

β-Ga_2O_3∶Dy~(3+)纳米棒束的制备和光致发光性质

采用水热法及后续热处理制备了-βGa2O3∶Dy3+纳米棒束。利用X射线粉末衍射(XRD),场发射电子扫描显微镜(FESEM)、发光光谱等测试手段对-βGa2O3∶Dy3+的物相、形貌、发光性质等进行了研究。FESEM等测试表明水热样品是由直径约100 nm,长约2μm的纳米棒组成的长径比约为3的羟基氧化镓(GaOOH)纳米棒束。经过900℃高温热处理,得到了形貌和尺寸基本保持不变的-βGa2O3∶Dy3+纳米棒束。光致发光测试表明,Dy3+的发光由分别归属于4F9/2-6H15/2的蓝光(460~505 nm,491 nm为最强峰)和4F9/26-H13/2的黄光(570~600 nm,580 nm为最强峰)组成。-βGa2O3基质可以有效地向Dy3+传递能量。与固相法样品相比,采用水热后续热处理方法制备的样品在分散性、形貌、能量传递和寿命方面明显优于固相法样品。     

白光LED用Sr0.955Al2Si2-xTixO8：Eu2+荧光粉的晶体结构和光谱特性

由高温固相反应制得Sr_0.955Al₂Si_2-xTi_xO₈：Eu²⁺（x=0~1.0）系列试样,研究了Ti⁴⁺置换Si⁴⁺对其晶体结构和光谱特性的影响。Ti⁴⁺以类质同相替代Si⁴⁺进入晶体晶格中,形成了连续固溶体,其晶胞参数a,b,c,β和晶胞体积V随Ti⁴⁺置换量呈线性递增。Ti⁴⁺置换Si⁴⁺对晶胞参数c的影响显著,b其次,a最小。荧光激发谱为宽带,位于230~400nm,由267nm、305nm、350nm和375nm 4个峰拟合成,表观峰值位于351nm;随着Ti⁴⁺置换量的增加,半高宽（FWHM）从105nm减小到93nm。发射光谱位于380~600nm,表观峰值位于407nm,可由406nm和441nm两峰拟合而成并且随Ti⁴⁺置换量增加线性红移,Ti⁴⁺进入晶格对长波长发射中心影响较少;Ti⁴⁺置换量为1.0时,表观发射峰位从407nm红移至417nm;利用试样荧光光谱和VanUitert经验公式,得出SrAl₂Si₂O₈：Eu²⁺中Sr²⁺的配位数为9。随着Ti⁴⁺置换量Si⁴⁺进入基质晶格,造成Eu-O距离变小,使得Eu²⁺所处的晶体场强度增强,发光中心Eu²⁺的5d能级分裂增大,造成Eu²⁺最低发射能级重心下移,两拟合谱峰峰位均呈线性红移。     

Sr0.955Al2-xBxSi2O8:0.025Eu2+荧光粉的制备、晶体结构及发光性能

通过高温固相反应在弱还原气氛下制备了Sr_0.955Al_2-xB_xSi₂O₈：0.025Eu²⁺（x=0~0.9）一系列荧光粉,研究了B（Ⅲ）取代基质晶格中的Al（Ⅲ）对荧光粉晶体结构和Eu²⁺发光性能的影响。B（Ⅲ）以类质同相取代基质晶格中Al（Ⅲ）,形成了连续固溶体。随着B（Ⅲ）取代量的增加,荧光粉的晶胞参数（a、b、c）和晶胞体积（V）呈线性递减,而晶胞参数（β）呈线性递增。荧光粉的激发光谱为位于225~400 nm的宽峰,表观峰值位于350 nm,激发峰的半高宽（FWHM）随着B（Ⅲ）取代量的增加,从90 nm减小到102 nm。发射光谱位于370~600 nm的宽峰,可拟合为409和447 nm两个峰,表观峰值位于409 nm。随着B（Ⅲ）取代量的增加,2个拟合峰位均出现蓝移且2个峰强度比呈线性递减。根据试样荧光光谱,通过Van Uitert经验公式计算得出SrAl₂Si₂O₈：Eu²⁺中Sr²⁺的配位数为9。随着B（Ⅲ）取代Al（Ⅲ）进入基质晶格,造成发光中心Eu与配体O距离增加,使得Eu²⁺所处的晶体场强度减小,发光中心Eu²⁺的5d能级分裂减小,造成Eu²⁺最低发射能级重心上移,2个拟合谱峰峰位均呈线性蓝移。     

γ-Zn3（PO4）2:Mn2+,Ga3+的发光性质及能量传递

采用高温固相法合成了Mn2+单掺杂及Mn2+,Ga3+共掺杂的γ-Zn3(PO4)2。γ-Zn3(PO4)2:Mn2+的发射峰位于620 nm,而γ-Zn3(PO4)2:Mn2+,Ga3+发射光谱有两个发射峰,其中一个发射峰位于507 nm,另一个发射峰位于620 nm。507 nm的发射峰来自于处于四面体晶体场中Mn2+(CN=4)的4T1g-6A1g能级跃迁,而620 nm的发射峰来自于处于八面体晶体场中Mn2+(CN=6)的激发态4T1g-6A1g的能级跃迁。在Mn2+,Ga3+共掺杂的样品中,八面体场中Mn2+的激发光谱与四面体场中Mn2+的发射光谱有显著的光谱重叠,满足共振能量传递条件,从而发生了Mn2+(CN=4)向Mn2+(CN=6)的能量传递,对此进行了证明及讨论。此外,Mn2+离子在四面体场及八面体场中的浓度分布随着Ga3+离子的掺入量而发生变化。Ga3+离子对Mn2+在四面体场与八面体场浓度比值起到调节作用。随着Mn2+离子和Ga3+离子浓度的增加,发射光谱中绿光强度与红光强度比值也逐渐增加。最终,发射光谱中绿光强度与红光强度的相对比值是由Mn2+离子浓度、Ga3+离子浓度及Mn2+(CN=4)向Mn2+(CN=6)的能量传递3个因素决定的。     

Solid-supported [2+2+2] cyclotrimerizations

The transition-metal-catalyzed [2+2+2] cyclotrimerization of a diyne and an alkyne provides a convergent route to highly-substituted aromatic rings. This reaction possesses distinct drawbacks, especially low chemo- and regioselectivities, which hamper its application in combinatorial synthesis. These problems have been solved by the development of solid-supported [2+2+2]-cycloaddition reactions. If conducted on a solid-support, this reaction enables rapid combinatorial access to diverse sets of carbo- and heterocyclic small-molecule arrays. The scope of this methodology has been investigated by examining different immobilization strategies, different diyne precursors, and a variety of functionalized alkyne reaction partners. Overall, isoindoline, phthalan, and indan libraries were assembled in good to excellent yields and with high purities.     

A photoionization study of the charge transfer reactions: Xe+ + O2 → O+2 + Xe and O+2 + Xe → Xe+ + O2

Photoionization mass spectrometer techniques have been employed to study the charge transfer reactions: Xe⁺ + O₂ → O⁺₂ + Xe and O⁺₂ + Xe → Xe⁺ + O₂. The results show the reaction of Xe⁺(²P_{$\text{3}\text{2}$}) ions with O₂ molecules is much more efficient than the reaction of Xe⁺(²P_{$\text{1}\text{2}$}) ions with O₂ molecules. The charge transfer reaction of O⁺₂ ions with Xe atoms was detected for O⁺₂ ions in the a ⁴Π_u state.     

Tethered 2 + 2 + 2 cycloaddition reactions of cobalt-cycloheptyne complexes

Cycloheptyne-dicobalt hexacarbonyl complexes, substituted by propargylic ether functions, undergo 2 + 2 + 2 cycloaddition reactions with alkynes to give tricyclic benzocycloheptanes; an all-intramolecular version of this transformation is also possible.     

NHC-catalyzed enantioselective [2 + 2] and [2 + 2 + 2] cycloadditions of ketenes with isothiocyanates

The enantioselective N-heterocyclic carbene-catalyzed formal [2 + 2] and [2 + 2 + 2] cycloaddition of ketenes and isothiocyanates were developed. Reaction with N-aryl isothiocyanates at room temperature favors the [2 + 2] cycloaddition, while reaction with N-benzoyl isothiocyanates at -40 °C favors the [2 + 2 + 2] cycloaddition.     

Intracellular Ruthenium-Promoted (2+2+2) Cycloadditions

Metal-mediated intracellular reactions are becoming invaluable tools in chemical and cell biology, and hold promise for strongly impacting the field of biomedicine. Most of the reactions reported so far involve either uncaging or redox processes. Demonstrated here for the first time is the viability of performing multicomponent alkyne cycloaromatizations inside live mammalian cells using ruthenium catalysts. Both fully intramolecular and intermolecular cycloadditions of diynes with alkynes are feasible, the latter providing an intracellular synthesis of appealing anthraquinones. The power of the approach is further demonstrated by generating anthraquinone AIEgens (AIE=aggregation induced emission) that otherwise do not go inside cells, and by modifying the intracellular distribution of the products by simply varying the type of ruthenium complex.     

Rhodium‐Catalyzed [3+2+2] and [2+2+2] Cycloadditions of Two Alkynes with Cyclopropylideneacetamides

It has been established that a cationic rhodium(I)/H₈‐binap complex catalyzes the [3+2+2] cycloaddition of 1,6‐diynes with cyclopropylideneacetamides to produce cycloheptadiene derivatives through cleavage of cyclopropane rings. In contrast, a cationic rhodium(I)/(S)‐binap complex catalyzes the enantioselective [2+2+2] cycloaddition of terminal alkynes, acetylenedicarboxylates, and cyclopropylideneacetamides to produce spiro‐cyclohexadiene derivatives which retain the cyclopropane rings.     

Studies on Synthetic Inorganic Ion Exchangers-III Quantitative Separations of Mg2+ -Pb2+, Zn2+ - Pb2+ Cu2+ - Pb2+, Al3+ - Pb2+, Zn2+ - Cd2+, and Mg2+ - Cd2+ on Lead Antimonate Columns

Abstract

A new inorganic ion exchanger, lead antimonate has been synthesized having an Pb:Sb ratio of 1:5 and cation exchange capacity of 1.46 mequiv./g. It is fairly stable in water and dilute solutions of acids, bases and salts. Ion distribution studies on twenty metal ions have been determined on this gel at pH 1,2,3 and 5. The following mixtures have been separated: Mg²⁺ - Pb²⁺, Zn²⁺ - Pb²⁺, Zn²⁺ - Pb²⁺, Cu²⁺ - Pb²⁺, Al³⁺ - Pb²⁺, Zn²⁺ - Cd²⁺ and Mg²⁺ - Cd²⁺. Mg²⁺ and Al³⁺ were removed with 0.4 M ammonium nitrate, Cu²⁺ and Zn²⁺ with 0.4 M ammonium nitrate + 0.1M nitric acid (1:1), Pb²⁺ with 0.5M nitric acid and Cd²⁺ with 0.25M nitric acid. A tentative structure of this material is proposed on the basis of chemical analysis, pH titrations, thermogravimetry and IR spectrophotometry.     

Rhodium catalysed [2+2+2] cycloadditions of acetylenes

Wilkinson's catalyst RhCl(PPh₃)₃ is an effective catalyst (0.5 – 2 mole %) for the rapid intermolecular trimerisation of 1,6-heptadiynes with monoacetylenes under mild conditions.