喹啉酰腙铜锌配合物的结构及荧光性质

合成了配合物{[Cu（L）（OAc）]·MeOH}_n（1）和[Zn（L）（OAc）]_n（2）（HL为喹啉-8-甲醛缩异烟肼）,并通过单晶X射线衍射、元素分析、红外光谱表征了结构。单晶衍射结果表明,除了结晶溶剂不同,2个配合物结构类似。每个配合物中,中心金属离子与来自烯醇化脱质子配体L^-的2个O原子和1个N原子,1个单齿配位的醋酸根和相邻配体4-吡啶N原子配位,形成一维链状结构。但配合物中金属离子的配位构型分别为扭曲的四方锥和三角双锥。在360 nm紫外光激发下,甲醇溶液中配合物2在510 nm左右有很强的荧光发射,这是由锌离子配位荧光增强效应所导致。     

喹啉酰腙铜锌配合物的结构及荧光性质

合成了配合物{[Cu（L）（OAc）]·MeOH}_n（1）和[Zn（L）（OAc）]_n（2）（HL为喹啉-8-甲醛缩异烟肼）,并通过单晶X射线衍射、元素分析、红外光谱表征了结构。单晶衍射结果表明,除了结晶溶剂不同,2个配合物结构类似。每个配合物中,中心金属离子与来自烯醇化脱质子配体L^-的2个O原子和1个N原子,1个单齿配位的醋酸根和相邻配体4-吡啶N原子配位,形成一维链状结构。但配合物中金属离子的配位构型分别为扭曲的四方锥和三角双锥。在360 nm紫外光激发下,甲醇溶液中配合物2在510 nm左右有很强的荧光发射,这是由锌离子配位荧光增强效应所导致。     

2个具有四重穿插框架和dia网络的5-羟甲基间苯二甲酸类Zn(Ⅱ)配位聚合物的合成、结构和荧光性质

在溶剂热条件下,5-羟甲基间苯二甲酸（5-（hydroxymethyl）isophthalic acid,H₂HIPA）和锌离子分别与1,4-双（2-甲基-1氢-咪唑-1-基）苯（1,4-bis（2-methyl-1H-imidazol-1-yl）benzene,1,4-BMIB）以及1,2-二（吡啶-4-基）乙烯（1,2-di（pyridin-4-yl）ethene,dpee）反应得到2个三维的配位聚合物[Zn（HIPA）（1,4-BMIB）]_n（1）和{[Zn（HIPA）（dpee）]·0.5dpee}_n（2）。单晶衍射揭示在配合物1中,锌离子中心呈现一个略微变形的四面体配位构型,而HIPA^2-和1,4-BMIB为简单连接体,构建出具有四重穿插和dia网络的框架。在2中,锌离子中心以五角双锥构型作为四连接节点分别连接2个HIPA^2-和dpee配体,仍然是一个具有dia网络的四重穿插框架。此外,dpee不仅作为辅助配体参与构建配合物2,而且还以客体分子的形式存在。固体紫外-可见光谱显示1和2在紫外区有强的吸收,同时固体荧光测试揭示它们具有蓝色荧光特征,分别在414和440 nm附近有强的荧光发射峰。     

3,4,5,6-四氟邻苯二甲酸与含氮配体的过渡金属配合物的合成、晶体结构及对Fe3+的荧光传感

利用过渡金属盐与3,4,5,6-四氟邻苯二甲酸（TFPT）、1,3-二（4-吡啶基）-丙烷（DPP）和1,4-二（1,2,4-三氮唑）-1-丁烷（BTB）经水热法合成了3个新的配合物：{[M（TFPT）（DPP）]·H₂O}_n（M=Cd（1）,Ni（2））,{[Cd（TFPT）（BTB）_0.5]·2H₂O}_n（3）。通过X射线单晶衍射分析测定了它们的结构。配合物1和2具有相似的一维链结构。中心金属离子表现为扭曲的[MO₄N₂]八面体构型。配合物3具有二维结构。中心金属离子表现为扭曲的[CdO₅N]八面体构型。配合物1和3分别在424 nm、442 nm处出现来自于配体的荧光发射,对应于配体的π^*-π的跃迁,配合物2在356 nm处有非常弱的荧光发射。不同金属阳离子对配合物1和3的荧光强度有不同程度的影响,并且通过荧光的猝灭机理,它们都能选择性检测Fe³⁺离子。     

2,5-噻吩二甲酸与菲咯啉构筑的稀土配合物:晶体结构，荧光性质和对Cu2+离子的荧光传感

稀土硝酸盐和2,5-噻吩二甲酸与菲咯啉在水热反应条件下合成了3个新的配合物,[Ln（2,5-tdc）_1.5（phen）（H₂O）]_n（Ln=Gd（1）,Tb（2）,Dy（3）;2,5-tdc=2,5-噻吩二甲酸根,phen=菲咯啉）。通过X射线单晶衍射确定了它们的晶体结构。配合物1~3为同构的2D网络结构。配合物1在340 nm激发下出现最大发射中心位于366和387 nm的宽峰,可归属于配体的π^*-π跃迁发射。配合物2在365 nm紫外灯照射下发绿光,其荧光发射光谱中出现了4个尖峰,位于491、545、588和620 nm处,对应于Tb³⁺的⁵D₄→⁷F_J（J=6~3）跃迁。配合物2的荧光寿命显示为单指数衰减,其值为（0.123±0.005）ms。配合物3的发射光谱中出现了2个尖峰,位于482和575 nm处,分别对应于Dy³⁺的⁴F_5/2→⁶H_15/2和⁴F_5/2→⁶H_13/2跃迁。另外,研究了配合物2的荧光传感能力,该配合物可作为荧光探针检测水溶液中的Cu²⁺离子。     

基于吡啶基三联吡啶配体的锌（Ⅱ）和镉（Ⅱ）配合物的晶体结构和荧光性质

在溶剂热条件下合成了配合物[Zn （2-pyterpy）₂]（ClO₄）₂·0.25H₂O （1）和[Cd （2-pyterpy）₂]₂（ClO₄）₄·2.33H₂O·CH₃OH （2）（2-pyterpy=4''-（2-吡啶基）-2,2''∶6'',2″-三联吡啶）,并通过元素分析、FT-IR光谱、X射线单晶衍射和X射线粉末衍射进行了表征。X射线单晶衍射结果表明,2个配合物属于三斜晶系,P1空间群。在激发波长为405 nm时,固态配合物1和2的荧光峰分别位于539和547 nm。在甲醇溶液中,配合物1和2的激发波长分别为357和352 nm,荧光峰分别为408和371 nm;亚稳态光酸mPAH1的最佳激发波长和荧光波长分别为467和556 nm。用mPAH1滴定配合物1,则mPAH1使配合物1在408 nm处的荧光猝灭,猝灭常数K_SV为2.961×10⁴ L·mol^-1,但荧光寿命基本不变,这归因于内滤效应。相反,用配合物1滴定mPAH1,则混合溶液在556 nm处的荧光增强,这归因于mPAH1使配合物1部分质子化。     

两个线形三核配合物的晶体结构及性质

合成并表征了2个新的线性三核配合物[Co₂^ⅢCo^ⅡL₂（μ-OAc）₄]（1）和[Ni₃L₂（μ-OAc）₂（CH₃OH）₂]·2H₂O（2）,其配体L为2-羟基-1,3-丙二胺和5-氟水杨醛缩合的产物。配合物1与DNA的作用通过紫外-可见光谱、荧光光谱、粘度实验和电化学方法进行了研究。紫外-可见光谱的结果表明配合物1与DNA的结合常数为2.43×10⁵ L·mol^-1。荧光光谱的研究结果表明配合物1能取代溴化乙锭和DNA结合,其淬灭常数为4.92×10³ L·mol^-1。配合物1和2的变温磁学性质研究表明在2个配合物的三金属中心之间均存在反铁磁性耦合。     

以苯四甲酸和双(咪唑基甲基)苯为配体的三维Cd-MOF材料的合成、结构及荧光性质

选择刚性的1,2,4,5-均苯四甲酸（H₄L）为主配体,以1,3-双（1H-咪唑-1-基甲基）苯（1,3-bib）为辅助配体,在水热条件下,与过渡金属离子Cd²⁺配位合成了配合物[Cd（L）_0.5（1,3-bib）（H₂O）]·H₂O（1）。利用元素分析、红外光谱、X射线单晶衍射、热重和X射线粉末衍射对其结构进行了表征,并研究了化合物的荧光性质。结果表明：配合物1属正交晶系,空间群Pbca,a=0.857 08（4）nm,b=1.912 23（10）nm,c=2.451 60（12）nm。配合物1中Cd²⁺与L^4-配体的羧基通过双齿螯合配位,通过1,3-bib连接形成三维网状结构。配合物1具有较强的荧光,其对丙酮溶剂、MnO₄^-、Hg²⁺离子有一定的荧光猝灭。     

2-甲基-2,5′-(乙烯基)-二-8-羟基喹啉锌配合物的合成与荧光特性

设计合成了8-羟基喹啉衍生物3和4以及它们的金属锌配合物5和6,化合物3和4经质谱(MS)、元素分析(EA)、红外光谱(IR)、紫外光谱(UV)、核磁共振氢谱( ¹H NMR)进行表征,并测定了它们的荧光性质,与2-甲基-8-羟基喹啉(λ_max=390 nm)比较表明,化合物3和4的荧光红移80～150 nm;用X射线单晶衍射仪测定了化合物3的晶体结构,晶体属于三斜晶系,空间群P1,a=0.706 87(5) nm,b=0.962 03(6) nm,c=1.221 09(8) nm,α=86.735(4)°,β=87.840(4)°,γ=74.333(4)°,V=0.798 01(9) nm³,Z=2,D_c=1.367 Mg·m^-3,μ=0.089 mm^-1,F(000)=344,wR₁=0.055 2,wR₂=0.158 1。化合物3的晶体结构确认了2-甲基-8-羟基喹啉甲酰化是在5位。测定了化合物5和6的荧光光谱及其荧光寿命,结果表明,化合物5和6发光的峰值为620 nm 和623nm,能够发出橙色的荧光,与2-甲基-8-羟基喹啉锌(λ_max=515 nm)比较,发生了明显的红移。化合物5和6的寿命分别为1.57 ns和1.77 ns,呈单指数衰减。     

三个包含酰胺型配体铜/锌配合物的合成、结构及荧光性质

合成并通过单晶衍射表征了3个配合物[CuLCl₂]·CH₃CN(1),[CuLBr₂]·CH₃CN(2)和[ZnL(NO₃)₂]·CH₃CN(3)(L=2-(5-氯-8-喹啉氧基)-1-(吡咯烷-1-基)乙酮)。在配合物1和2中,五配位的铜离子采取扭曲的四方锥配位构型,与来自配体L的2个氧原子和1个氮原子及2个卤离子配位。而在配合物3中,锌离子与1个三齿配位的配体L,1个单齿配位的硝酸根和1个双齿配位的硝酸根配位,配位构型为扭曲的八面体。乙腈溶液中,配合物1和2在410 nm处的最大荧光发射峰与配体L的相似,强度有所降低。而配合物3由于配体到锌离子之间的能量转移,最大荧光发射峰红移至430 nm。     

2-羟基-1-萘甲醛缩-2-萘甲酰腙对Zn2+的选择性识别

设计合成了识别Zn²⁺的荧光传感分子--2-羟基-1-萘甲醛缩-2-萘甲酰腙(3)。 通过红外光谱、核磁共振谱和质谱测试技术表征了其结构。 利用其光谱性质研究了该物质对几种过渡金属离子的识别性质,初步探讨了其结合模式。 结果表明,在乙腈介质中,受体分子3表现出对Zn²⁺良好的选择性,Zn²⁺的加入导致受体分子3的吸收光谱在435 nm处出现1新峰,其吸光度逐渐增强,同时于239、302、330、342和387 nm处观察到5个清晰的等吸收点;在516 nm处荧光增强101倍,而其它过渡金属只引起受体分子]3的荧光略微增强。 Job法实验揭示受体分子3与Zn²⁺的结合比为1∶1。     

水杨醛-4-甲氧基苯甲酰腙识别锌离子的研究

设计合成了荧光传感分子水杨醛-4-甲氧基苯甲酰腙(SAMB),通过IR、1HNMR和元素分析确证了其结构,利用紫外-可见吸收光谱和荧光光谱考察了其对不同阳离子的识别作用。结果表明,SAMB的荧光发射对锌离子表现出高选择性响应,且形成1∶1型配合物。乙醇中锌离子的加入导致SAMB的荧光增强328倍,而其他过渡金属离子只引起SAMB的荧光的略微增强。初步探讨了受体分子与锌离子的结合模式与荧光增强机理。     

Dansyl-anthracene dyads for ratiometric fluorescence recognition of Cu2+

Dansyl-anthracene dyads 1 and 2 in CH(3)CN-H(2)O (7:3) selectively recognize Cu(2+) ions amongst alkali, alkaline earth and other heavy metal ions using both absorbance and fluorescence spectroscopy. In absorbance, the addition of Cu(2+) to the solution of dyads 1 or 2 results in appearance of broad absorption band from 200 nm to 725 nm for dyad 1 and from 200 nm to 520 nm for dyad 2. This is associated with color change from colorless to blue (for 1) and fluorescent green (for 2). This bathochromic shift of the spectrum could be assigned to internal charge transfer from sulfonamide nitrogen to anthracene moiety. In fluorescence, under similar conditions dyads 1 and 2 on addition of Cu(2+) selectively quench fluorescence due to dansyl moiety between 520-570 nm (for 1)/555-650 nm (for 2) with simultaneous fluorescence enhancement at 470 nm and 505 nm for dyads 1 and 2, respectively. Hence these dyads provide opportunity for ratiometric analysis of 1-50 μM Cu(2+). The other metal ions viz. Fe(3+), Co(2+), Ni(2+), Cd(2+), Zn(2+), Hg(2+), Ag(+), Pb(2+), Li(+), Na(+), K(+), Mg(2+), Ca(2+), Ba(2+) do not interfere in the estimation of Cu(2+) except Cr(3+) in case of dyad 1. The coordination of dimethylamino group of dansyl unit with Cu(2+) causes quenching of fluorescence due to dansyl moiety between 520-600 nm and also restricts the photoinduced electron transfer from dimethylamino to anthracene moiety to release fluorescence between 450-510 nm. This simultaneous quenching and release of fluorescence respectively due to dansyl and anthracene moieties emulates into Cu(2+) induced ratiometric change.     

Metal-dependent global folding and activity of the 8-17 DNAzyme studied by fluorescence resonance energy transfer

The 8-17 DNAzyme is a DNA metalloenzyme catalyzing RNA transesterification in the presence of divalent metal ions, with activity following the order Pb2+ > Zn2+ >Mg2+. Since the DNAzyme has been used as a metal ion sensor, its metal-induced global folding was studied by fluorescence resonance energy transfer (FRET) by labeling the three stems of the DNAzyme with the Cy3/Cy5 FRET pair two stems at a time in order to gain deeper insight into the role of different metal ions in its structure and function. FRET results indicated that, in the presence of Zn2+ and Mg2+, the DNAzyme folds into a compact structure, stem III approaching a configuration defined by stems I and II without changing the angle between stems I and II. Correlations between metal-induced folding and activity were also studied. For Zn2+ and Mg2+, the metal ion with higher affinity for the DNAzyme in global folding (Kd(Zn) = 52.6 microM and Kd(Mg) = 1.36 mM) also displays higher affinity in activity (Kd(Zn) = 1.15 mM and Kd(Mg) = 53 mM) under the same conditions. Global folding was saturated at much lower concentrations of Zn2+ and Mg2+ than the cleavage activities, indicating the global folding of the DNAzyme occurs before the cleavage activity for those metal ions. Surprisingly, no Pb2+-dependent global folding was observed. These results suggest that for Pb2+ global folding of the DNAzyme may not be a necessary step in its function, which may contribute to the DNAzyme having the highest activity in the presence of Pb2+.     

N,N-二甲基吡啶苯甲醛缩对二甲氨基苯甲酰腙的合成及对Cu2+的选择性识别

设计合成了可用于识别铜离子的化合物N,N-二甲基吡啶苯甲醛缩对二甲氨基苯甲酰腙(1), 通过¹H NMR, ¹³C NMR和MS等对其结构进行了表征; 采用荧光光谱和吸收光谱法研究了化合物1与金属离子间的相互作用. 结果表明, 化合物1对Cu²⁺ 呈现良好的选择性, Cu²⁺ 的加入使化合物1的荧光强度增强12.5倍, 加入其它金属离子如Fe³⁺, Zn²⁺, Pb²⁺, Hg²⁺, Cd²⁺, Co²⁺, Ni²⁺, Li⁺, K⁺, Ca²⁺, Mg²⁺ 和 Ag⁺, 仅引起化合物1荧光强度的微降. 采用双倒数线性回归拟合法计算可知, 化合物1与Cu²⁺ 形成了1: 1型强发光配合物, 结合常数为2.0×10⁷ L/mol.     

A novel turn-on fluorescent probe for Hg2+ detection based on rhodamine B spirolactam derivative

ABSTRACT

In this work, a new turn-on fluorescent probe 1 for Hg²⁺ ions detection based on rhodamine B spirolactam was reported. Among tested metal ions, probe 1 shows high selectivity towards Hg²⁺ in the the mixture solution of methanol and 0.02 M HEPES buffer (V/V = 9:1, pH = 7.2). No absorption and emission band of probe 1 was observed in the range from 450 to 700 nm. While only addition of Hg²⁺ to probe 1 could lead to appearance of a new absorption band centered at 553 nm and a fluorescence emission band around 577 nm upon excitation at 520 nm. Moreover, it exhibits excellent linear relationship (R² = 0.9993) between fluorescence intensity at 577 nm and the concentration of Hg²⁺ from 1.6 to 32 μM. The sensing mechanism was proven to be spirolactam ring open induced by Hg²⁺ through ¹H NMR, MS, absorption and fluorescence spectra. In addition, probe 1 could detect Hg²⁺ in real water samples and on filter paper, which demonstrates its application in environment science.     

基于羟苯基苯并咪唑的Zn2+比率荧光探针

通过羰基将两分子2-(4-氨基-2-羟苯基)苯并咪唑(4-AHBI)连接,合成了结构高度对称的新化合物N,N′-二-[3-羟基-4-(2-苯并咪唑)苯基]脲(C27H20N6O3,1),测试了不同溶剂条件下1的紫外吸收和荧光发射光谱,研究了1对Zn2+的选择性识别作用。结果表明,随着溶剂极性的增大,1的紫外吸收峰发生蓝移,激发态分子内质子转移(ESIPT)荧光发射峰明显增强。与4-AHBI相比,1在乙腈溶液中的紫外吸收强度增强约3.5倍,最大吸收峰红移8 nm,荧光发射增强8倍多。1在乙腈溶液中的Zn2+荧光响应行为表明1与Zn2+的结合将导致1在445 nm处的荧光强度不断降低,而在395 nm处出现的新峰的荧光强度不断增强,具有比率荧光探针的特点,而且检测范围较宽,可达1×10-6-1×10-2 mol.L-1。     

"Turn-on" fluorescent sensor for Hg2+ via displacement approach

A new Cu2+ compound Cu- NB, (where H2 NB is bis(2-hydroxyl-naphthalene-carboxaldehyde) benzil dihydrazone) was synthesized as a highly selective fluorescence chemosensor for the detection of Hg2+ in aqueous media through a displacement "turn-on" signaling strategy. Whereas the coordination of Cu2+ resulted in a considerable quenching of the typical luminescence of the naphthol rings in Cu-NB, the addition of Hg2+ ion led to a dramatic increase in the emission intensity of Cu-NB at about 530 nm (excitation at 430 nm). The competitive fluorescent experiments showed that alkali, alkaline earth metal ions, the group 12 metals Zn2+, Cd2+, the first-row transition-metal ions such as Mn2+, Fe2+, Co2+, and Ni2+, as well as Pb2+ could not inhibit the Hg2+-binding fluorescent enhancement. It is postulated that the existence of Cu2+ in the luminescent probe Cu-NB could turn away the interferences of other metal cations from Hg2+ detection. The optical responses of the free ligand upon addition of Cu2+ ion, and of the Hg-H2NB compound upon the addition of Cu2+ were also investigated for comparisons.     

A ratiometric fluorescence probe for selective visual sensing of Zn2+

A simple ratiometric fluorescence probe based on vinylpyrrole end-capped bipyridine for the visual sensing of Zn2+ under aqueous physiological pH (6.8-7.4) is described. The fluorophores 3a-c showed strong emission around 537 nm in acetonitrile with a quantum yield of 0.4. In buffered (HEPES, pH 7.2) acetonitrile-water mixture (9:1 v/v), titration of transition metal salts to 3c showed strong quenching of the emission at 547 nm except in the case of Zn2+, which resulted in a red-shifted emission at 637 nm. Alkali and alkaline earth metal salts could not induce any considerable changes to the emission behavior of 3a-c. The binding of Zn2+ was highly selective in the presence of a variety of other metal ions. Though Cu2+ quenches the emission of 3c, in the presence of Zn2+, a red emission prevails, indicating the preference of 3c toward Zn2+. Job plot and Benesi-Hildebrand analysis revealed a 1:1 complexation between the probe and the metal ion. The selective visual sensing of Zn2+ with a red emission is ideally suited for the imaging of biological specimens.     

A New Fluorescent Chemosensor for Cu2+ Based on a Dianthracene-Derivative

Abstract

Besides being of interest in photochemistry, photoinduced electron transfer (PET) is a process largely used in the design of fluorescent ion sensing molecules. One of the simplest systems is based on fluorescent aromatic groups linked to amino groups and proposed as possible fluorescent transition metal ion chemosensor [1]. In this case, the fluorescence of the fluorophore “ligths on” when the amino group is complexed. On the other hand, in the absence of metal ions, the fluorescence is quenched by a PET originating from the nitrogen lone electron pairs [2]. We prepared a new fluorescent chemosensor, abbreviated as Ant-NH-O-O-NH-Ant (shown in Fig. 1) in which the intramolecular PET is expected to be efficient. The chemosensor consists of a metal-binding dioxodiamino unit linked to two light-emitting anthracene fragments. This type of supramolecules when irradiated in methanol solution (conc. 1.89—10^?5 M.) at 368 nm displays a characteristic fluorescence spectrum for anthracene group with the most intensive band at 415 nm [Fig. 2(a)]. The emission is slightly enhanced upon coordination of such metal ions as Ni²⁺ and Zn²⁺ by the ligand fragment of the Ant-NH-O-O-NH-Ant molecule [Fig. 2(b) and (d)]. However, much higher intensity of emission is observed in the case of Cu²⁺ complex [see Fig 2(c)]. The fluorescence enhancement is presumably due to suppression of photoinduced fluorophore-to-metal electron-transfer mechanism.