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1.
以Ru为多相成核剂和硬脂酸为表面活性剂,在多元醇溶液中合成了CoCu双金属纳米复合物,并在甘油选择性氢解制丙二醇中评价了其催化性能.结果表明,硬脂酸作为结构导向剂可诱使Co纳米晶沿着一维方向生长,形成纳米线.当Co 2+和Cu 2+共存于多元醇溶液中,由于Cu 2+较高的氧化还原电位,首先被还原成Cu 0,进而增长成100~300 nm的球形粒子.在Cu粒子表面,Co 2+被还原成核,在表面活性剂的结构导向作用下生长为长度为100~500 nm的纳米棒,从而形成海胆状CoCu双金属纳米复合结构.在甘油选择性氢解制丙二醇反应中,海胆状CoCu双金属复合催化剂的单位表面活性与丙二醇选择性均明显高于单金属Co纳米线和Cu球形粒子,在Co 90Cu 10催化剂上获得33%的丙二醇收率.这可能是由于Co和Cu界面的协同效应促进了甘油的转化所致. 相似文献
2.
以双中心模型为基础, 理论研究了LiNbO 3:Cu:Ce晶体在稳态情况下的非挥发双光双步全息存储性能. 研究中考虑了在晶体深能级中心Cu +/Cu 2+ 与浅能级中心Ce 3+/Ce 4+ 之间由隧穿效应引起的电荷直接交换过程. 结果表明, 总的空间电荷场大小主要由深能级上的空间电荷场所决定, 并且非挥发全息存储性能主要由隧穿效应引起的深能级中心Cu +/Cu 2+ 与浅能级中心Ce 3+/Ce 4+ 之间的电荷直接交换过程所决定. 与隧穿效应相关的材料参数对于非挥发双光双步全息存储的性能起到了至关重要的作用. 相似文献
3.
用化学镀方法在碳纳米管表面沉积了具有不同镍/钴成分配比的镍钴磷合金层.讨论了Co 2+与Ni 2+的浓度比、镀液温度、pH值对沉积速率的影响.并利用场发射扫描电镜、透射电镜、X射线衍射仪、能谱仪和磁性测量仪对镍钴磷包覆碳纳米管进行了系统的结构和性能表征.结果表明:当镀液中Co 2+与Ni 2+的浓度比为1,pH值为9时沉积速率最大;镀液温度的升高会使沉积速率增大.磁性测试结果显示碳纳米管表面镀覆Ni-Co-P镀层后,其磁性能对镀层中的Ni、Co相对含量有强烈的依赖性.当Co 2+: Ni 2+=2:1时,饱和磁化强度最大.矫顽力分别在Co 2+: Ni 2+=1:2和Co 2+: Ni 2+=4:1时有2个峰值; 而磁导率分别在Co 2+: Ni 2+=1:4和Co 2+: Ni 2+=4:1时有2个峰值. 相似文献
4.
利用稀土直接掺杂工艺合成了一种“常光充能”型电子陷获材料CaS:Eu,Sm,它不仅具有CaS:Eu无机发光材料的荧光光谱特性,而且具有红外升频转换特性,可将0.8~1.6μm的红外光直接转换为~672nm的红光、量子效率高达76%,是一种优于CaS:Eu的光转换农膜添加剂.而共掺Eu 2+、Sm 3+和Cu +的CaS荧光粉有望成为一种性能优于光转换农膜添加剂CaS:Eu 2+,Cu +、可人工模拟叶绿素吸收光谱的新型农用转光膜材料. 相似文献
5.
胆绿素(BV)及其二甲酯(BVE)是一种生物内源色素,他们在溶液中具有极弱的荧光,量子产率小于0.01%。然而,随着锌离子的加入,情况发生了变化. BVE-Zn 2+配合物的荧光强度大大增强,荧光QY可提高到∽5%. 本文研究了BVE-Zn 2+络合物在乙醇、正丙醇和二甲基亚砜溶液中的超快激发态动力学,以揭示其荧光增强的机理. 结果表明,BVE能与锌离子在溶液中形成1:1的稳定配合物,BVE分子结构在复合物中较为刚性,能量上更稳定. 利用皮秒时间分辨荧光光谱和飞秒瞬态吸收光谱技术,发现BVE-Zn 2+配合物在二甲基亚砜中具有较小的非辐射速率常数,这是其高荧光量子产率关键原因. 相似文献
6.
We report on the calculations of transition wavelengths and weighted oscillator strengths for 2s 22p 6-2s2p 6np (4 ≤ n ≤ 20) electric dipole (E1) transitions of Cu 19+ ion. The flexible atomic code (FAC) has been adopted for the calculations. Comparisons are made with the experimental data available, showing that the present results for 4 ≤ n ≤ 6 are more accurate than the previous calculated values. Furthermore, combining the quantum defect theory (QDT) with the transition energies of 2s 22p 6-2s2p 6np, the quantum defects for 2s2p 6np Rydberg series of Cu 19+ ion are determined. In addition, the energies of any highly excited states ( n > 20) for this series can be reliably predicted using the QDT and the given quantum defects. The ionization energies for Cu 19+ and Cu 20+ ions are also calculated and they excellently accord with previous experimental and calculated values. 相似文献
7.
通过简单的步骤合成了一个新型的N-(2-羟基-5-氯二苯酮基)-N'-[2-羟基-5-偶氮苯基-苯甲醛]-1,2-二苯胺受体,并有很高的产率.利用紫外光谱研究了受体的阴离子识别的性质.结果表明受体对F -、AcO -和H 2PO 4-有很高的结合能力,而对Cl -、Br -和I -没有结合能力.在受体的二甲基亚砜溶液中加入三种有结合能力的阴离子时,溶液展示了从无色到黄色的明显颜色变化,可以通过裸眼识别.在其它卤素离子存在下受体可以担当氟离子的传感器.紫外数据证明受体与阴离子通过氢键的相互作用形成1:1化学计量比的复合物. 相似文献
8.
基于自旋-轨道-晶格Hamilton量,应用团簇自洽场方法,研究了双层钙钛矿结构材料K 3Cu 2F 7基态的晶格、磁及轨道结构,发现近孤立的双层的对称破缺和Jahn-Teller晶格畸变使得Cu 2+离子在每层内交替占据 z 2-x 2〉/ z 2-y 2〉轨道,进而导致双层的层间表现为强的反铁磁耦合,层内为弱的铁磁耦合.强反铁磁耦合导致层间 相似文献
9.
合成了铽的配合物[TbL] (ClO 4) 3(L: 2, 2, 2', 2'-四[N-苯基-N-苄基(乙酰胺)-2-氧甲基]丁醚), 通过离子交换反应将配离子[TbL] 3+插层组装到蒙脱土(MMT)层板间, 制备出了新型复合发光材料 [TbL] 3+-MMT.用元素分析、X射线衍射、傅氏变换红外光谱和紫外-可见光谱对材料进行了表征, 对其荧光性质进行了研究.结果表明, 复合发光材料保持了蒙脱土良好的层柱结构特征和[TbL] 3+离子的笼状结构特征, [TbL] 3+离子以单层形式分布于蒙脱土层板间.在紫外光激发下, 复合发光材料发出较强的绿色荧光, 其发射光谱与相应配合物的发射光谱相似.与相应纯配合物比较, 复合发光材料单位质量Tb 3+的相对荧光强度、荧光单色性和光稳定性有显著改善, 其激发波长向可见光区发生明显位移, 说明插层组装对相应配合物的激发波长有一定的调制作用. 相似文献
10.
采用高温熔融退火法制备了系列 80TeO 2-10Bi 2O 3-10TiO 2-0.5Er 2O 3-xCe 2O 3 (x=0,0.25, 0.5,0.75,1.0 mol%)和(80-y) TeO 2-10Bi 2O 3-10TiO 2-yWO 3-0.5Er 2O 3-0.75Ce 2O 3 (y=3,6,9,12 mol%)的碲铋酸盐玻璃.测试了玻璃样品400-1700 nm范围内的吸收光谱, 975 nm抽运下的上转换发光谱和1.53 μm波段荧光谱, 以及808 nm激励下的Er 3+离子荧光寿命和无掺杂玻璃样品的Raman光谱, 并结合Judd-Ofelt理论和McCumber理论计算了Er 3+离子光谱参数.结果表明, 在掺Er 3+碲铋酸盐玻璃中引入Ce 3+离子进行Er 3+/Ce 3+共掺, 通过Er 3+离子 4I 11/2能级与Ce 3+离子 2F 5/2 能级间基于声子辅助的能量传递过程,可以有效抑制Er 3+离子上转换发光并明显增强其 1.53 μm波段荧光;同时,在现有Er 3+/Ce 3+共掺玻璃组分基础上引入WO 3, 可进一步提高1.53 μm波段荧光并展宽其荧光发射谱. 研究结果对于获取优异光谱特性的宽带掺Er 3+光纤放大器玻璃基质具有实际意义. 相似文献
11.
Rhodamine B 8-hydroxy-2-quinolinecarboxaldehyde Schiff base ( 1) has been investigated as a colorimetric and fluorescent “off-on” probe for the recognition of Cu 2+ in aqueous solution. Probe 1 was synthesized by condensation of rhodamine B hydrazide and 8-hydroxy-2-quinolinecarboxaldehyde, which exhibited good selectivity for Cu 2+ among a range of biologically and environmentally important metal ions. The Cu 2+ recognition event undergoes a Cu 2+ promoted hydrolysis of probe 1 to release rhodamine B and the recognition process is barely interfered by other coexisting metal ions. Figure New application of Rhodamine B 8-hydroxy-2-quinolinecarboxaldehyde Schiff base as a colorimetric and fluorescent “off-on” probe for Cu 2+ in CH 3CN-H 2O (1:1, v/v, HEPES 10 mM, pH?=?7.0) solution has been developed 相似文献
12.
Here, three Schiff bases 3a-c, differing by the substitutions (–H, –Cl, and –N(CH3)2) on the phenyl ring, have been designed and synthesized via the reaction of ortho-aminophenol with benzaldehyde, 2,4-dichlorobenzaldehyde and para-dimethylamine benzaldehyde in 1:1 molar ratio with favourable yields of 89–92%, respectively. Their structural characterizations were studied by FT-IR, NMR, MALDI-MS and elemental analysis. The fluorescence behaviours of compounds 3a and 3b exhibited a severe aggregation caused quenching (ACQ) effect in EtOH/water system. On the contrary, compound 3c had an obvious J-aggregation induced emission (AIE) feature in EtOH/water mixture (v/v?=?1:1), and exhibited excellent sensitivity and anti-interference towards Cu2+ with the limit of detection (LOD) of 1.35?×?10–8 M. Job’s plot analysis and MS spectroscopic study revealed the 2:1 complexation of probe 3c and Cu2+. In addition, probe 3c was successfully applied to the determination of Cu2+ in real aqueous samples. 相似文献
13.
We have rationally constructed a novel ratiometric and near-infrared Cu 2+ fluorescent probe based on a tricarbocyanine chromophore. The new probe NIR-Cu showed a ratiometric fluorescent response to Cu 2+ with a large emission wavelength shift (up to 142 nm) in the far-red to near-infrared region. The probe also displayed a large variation in the fluorescence ratio (I 636/I 778) to Cu 2+ species with high sensitivity and selectivity. Additionally, the developed probe NIR-Cu was suitable for fluorescence imaging of Cu 2+ in living cells and mice. 相似文献
14.
A new pyrene derivative (chemosensor 1) containing a picolinohydrazide moiety exhibits high selectivity for Cu 2+ ion detection in mixed aqueous media (CH 3OH:H 2O = 7:3). Significant fluorescence enhancement was observed with chemosensor 1 in the presence of Cu 2+. However, the metal ions Ag +, Ca 2+, Cd 2+, Co 2+, Cu 2+, Fe 2+, Fe 3+, Hg 2+, K +, Mg 2+, Mn 2+, Ni 2+, Pb 2+, and Zn 2+ produced only minor changes in fluorescence for the system. The apparent association constant ( K
a) of Cu 2+ binding in chemosensor 1 was found to be 2.75*10 3 M −1. The maximum fluorescence enhancement caused by Cu 2+ binding in chemosensor 1 was observed over the pH range 5–8. Moreover, by means of fluorescence microscopy experiments, it is demonstrated that 1 can be used as a fluorescent probe for detecting Cu 2+ in living cells. 相似文献
15.
A 1,8-naphthalimide derivative with a reactive aliphatic hydroxyl was designed and synthesized as a fluorescent probe. Its structure was characterized by IR, 1H NMR, 13C NMR, LC-MS and HPLC. The probe showed high selectivity and sensitivity to Hg 2+ over other metal ions such as Pb 2+, Na +, K +, Cd 2+, Cr 3+, Zn 2+, Cu 2+, Ni 2+, Ca 2+, Fe 3+, Fe 2+, Co 2+, Mn 2+ and Mg 2+ in MeCN/H 2O (15/85, v/v). The increase in fluorescence intensity was linearly proportional to the concentration of Hg 2+ in the range of 18–40 μM with a detection limit of 1.38 × 10 ?7 mol/L. The probe could work in a pH span of 4.3–9.0 and respond to Hg 2+ quickly with strong anti-interference ability. Job’s plot suggested a 1:2 complex of the probe and Hg 2+. 相似文献
16.
A new thiophenyl pyrazoline probe for Cu 2+ in aqueous solution was synthesized and characterized by IR, NMR, HRMS and X-ray analysis. The probe displays remarkably high selectivity and sensitivity for Cu 2+ with a detection limit of 1.919?×?10 ?7 M in aqueous solution (EtOH:HEPES = 1:1, v/v, 0.02 M, pH?=?7.2). In addition, the probe is further successfully used to image Cu 2+ in living cells and the probe possesses good reversibility. A new thiophenyl pyrazoline probe can be used to image Cu 2+ in living cells with good reversibility 相似文献
17.
In this work, the dipod 9,10-bis(8-quinolinoxymethyl)anthracene ( 1) and for comparison, monopod 9-(8-quinolinoxymethyl)anthracene ( 2) have been synthesized. The fluoroionophore 1 in pH 7.1 HEPES buffered CH 3CN:H 2O (4:1 v/v) solution shows quenching only with Cu 2+ with lowest limit of detection 150 nM, amongst various metal ions. Fluoroionophore 1 could also be applied to sense Co 2+ with lowest limit of detection 600 nM. By modulating the pH of the solution and concentration of Cu 2+, 1 shows respective “On-Off-On” and “On-Off” fluorescent switching. The self-assembly of two Cu 2+ ions and two molecules of fluoroionophore 1 to form closed structure [Cu 2(L) 2] 4+ seems to be responsible for nanomolar sensitivity towards Cu 2+. The combination of delayed second protonation of 1 (pK a2?=?2.6) and stepwise protonation of [Cu 2 L 2] 4+ causes unusual stability of [Cu( LH) 2] 4+ even at pH?<?2. Figure The fluoroionophore 1 shows quenching only with Cu 2+ with lowest limit of detection 150 nM. The combination of delayed second protonation of 1 (pK a2?=?2.6) and stepwise protonation of [Cu 2 L 2] 4+ causes unusual stability of [Cu( LH) 2] 4+ even at pH?<?2. 相似文献
18.
A new fluorescent probe based on a bis-benzimidazole diamide N 2, N 2′- bis[(1-ethyl-benzimidazol-2-yl)methyl]biphenyl-2,2′-dicarboxamide ligand L 1 with a biphenyl spacer group and a Copper(II) trinuclear metallacycle has been synthesized and characterized by X-ray single crystallography, elemental and spectral (FT-IR, 1H & 13C NMR, UV-Visible) analysis. The fluorescence spectra of L 1 in MeOH show an emission band centered at 300 nm. This band arises due to benzimidazolyl moiety in the ligating system. The diamide L 1 in the presence of Cu 2+ show the simultaneous ‘quenching’ of (300 nm) and ‘enhancement’ of (375 nm) emission band. Similar fluorescence behavior was found in water–methanol mixture (9:1). The new emission band at 375 nm is attributed to intra ligand π–π* transition of the biphenyl moiety. L 1 exhibited high selectivity and sensitivity towards Cu 2+ in both the medium over other common metal ions like Ni 2+, Co 2+, Mn 2+, Mg 2+, Zn 2+, Pb 2+ and Hg 2+. The binding constant with Cu 2+ was calculated by the Benesi-Hildebrand equation. Selective “off-on-off” behavior of L 1 in methanol has also been studied. The fluorescent intensity of 375 nm bands in L 1 enhances (turns-on) upon addition of Cu 2+ and quenches (turn-off) upon addition of Na 2-EDTA. 相似文献
19.
In this study, we report the synthesis of new Schiff base E-1-(((1-benzylpiperidin-4-yl)imino)methyl)naphthalenee-2-ol ( L) and evaluation of its fluorescence response toward Cu 2+ ion. Preliminary, solvent effect, metal selectivity and metal ligand ratio were analyzed through UV-Visible study. Fluorescence response toward Cu 2+ was carried to assess the fluorescent property of synthesized Schiff base. The probe exhibited a higher fluorescence enhancement in the presence of Cu 2+ over other metal ions (Ni 2+, Zn 2+, Hg 2+, Co 2+, Cd 2+, Al 3+, Fe 2+, and Pb 2+). The binding stoichiometry between L and Cu 2+ has been investigated using Job’s plot and Benesi-Hildebrand equation and it was found that ligand L can form 1:1 L-Cu 2+ complex with binding constant ( K a) of 4?×?10 4 LM ?1. 相似文献
20.
A new 7-nitrobenz-2-oxa-1,3-diazole (NBD) derived fluorescent probe ( 1) exhibiting high selectivity for Cu 2+ detection, produced significant fluorescence quenching in the presence of Cu 2+ ion, while the metal ions Ca 2+, Cd 2+, Co 2+, Fe 2+, Hg 2+, Mg 2+, Mn 2+, Ni 2+ and Zn 2+ produced only minor changes in fluorescence. The apparent association constant ( K
a) for Cu 2+ binding in chemosensor 1 was found to be 1.22 × 10 3 M −1. The maximum fluorescence quenching activity caused by Cu 2+ binding to 1 was observed over the pH range 6–10. 相似文献
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