A novel multisignaling optical-electrochemical chemosensor for anions based on tetrathiafulvalene

[structure: see text] A multisignaling optical-electrochemical receptor for anions based on a triad with anthracene and TTF units was prepared. It showed a unique selectivity for fluoride ion over various anions with dramatic fluorescence enhancement in neutral condition and displayed a special recognition of H2PO4(-) in electrochemical studies with remarkable cathodic displacement of the first oxidation potential E(ox)1 of the TTF unit.     

Host-guest complexation of a fluorescent and electrochemical chemsensor for fluoride anion

Host-guest complexation of a ferrocenenylphalene dyad 1, 1,1'-diaceylferrocenyl-3-hydroxyl-2-naphthoylhydrazone, as a fluorescent and electrochemical chemosensor for fluoride anion, was investigated. Crystal structure analysis revealed that the two naphthyl arms of compound 1 positioned in the same side about the ferrocene moiety and interacted through pi-pi stacking interactions. The intermolecular pi-pi stacking interactions and the C-H...pi interactions between the ferrocene moieties and the naphthalene rings linked the molecules together featuring a two-dimensional layered structure. Fluorescence titrations of compound 1 indicated that in the presence of F- and H2PO4-, the emission intensities enhanced significantly. Electrochemical titrations revealed that compound 1 sensed the F- anion in high selectivity with a cathodic shift of 120 mV, and had no sense in recognizing H2PO4- anion. 1H NMR titrations demonstrated that while compound 1 hydrogen-bonded to H2PO4- forming simple 1 : 1 host-guest complex, further addition of F- induced the deprotonation of compound 1.     

Tripodal nitro-imidazolium receptor for anion binding driven by (C-H)+- - -X- hydrogen bonds

[structure: see text] A positively charged tripodal receptor with nitro groups in the imidazolium rings was designed, synthesized, and characterized for its anion binding strength. The receptor shows strong affinity and high selectivity for Cl- through (C-H)+- - -X(-) hydrogen bonds wherein charge-charge and charge-dipole electrostatic interactions dominate. The association constant with chloride anion in a 9:1 mixture of acetonitrile-d3 and DMSO-d6 is measured to be 1.1 x 10(6) M(-1). The receptor also shows reasonably high affinity toward H2PO4-.     

Synthesis, spectroscopic, electrochemical and Pb2+-binding studies of tetrathiafulvalene acetylene derivatives

A series of tetrathiafulvalene acetylene derivatives, [TTF-Ctriple bondC-A] [A=C6H4N(CH3)2-4 (1), C6H4OCH3-4 (2), C6H5 (3), C6H4F-4 (4), C6H4NO2-4 (5), C5H4N-2 (6), C5H4N-3 (7), and C5H4N-4 (8)], have been designed and synthesized to provide insight into the nature of the donor-acceptor interaction via a pi-conjugated triple bond. The X-ray crystal structure of [TTF-(Ctriple bondC)-C6H4OCH3-4] (2) reveals that the phenyl ring linked by acetylene is almost coplanar to the plane of TTF with a dihedral angle of 3.6 degrees. The strong intermolecular C-H...O hydrogen bonding was found to direct the molecular helical assemblies with a screw pitch of 5.148 A when viewed along the a-axis. Spectroscopic and electrochemical behaviors of the tetrathiafulvalene acetylene derivatives demonstrate that the TTF unit interacts with the electron-accepting group through the triple bond, thus leading to the intramolecular charge transfer. The pyridine-substituted TTF compounds 6-8 show remarkable sensing and coordinating properties toward Pb2+. Comparison of the spectroscopic and electrochemical properties and the calculation at the B3LYP/6-31G* level available in Gaussian 03 reveals that varying the bridged unit of the TTF-pi-A system from a double bond to a triple bond leads to positive shifts for the first and second oxidation potentials of the TTF moieties, while the extent of intramolecular charge transfer interactions through the pi-conjugated triple bond is smaller than that through the double bond.     

Imidazolium-based macrocycles as multisignaling chemosensors for anions

A series of structurally novel anion receptors , , and in which a ferrocene unit and a fluorescent moiety are linked to two imidazolium rings have been designed and prepared from 1,1'-bis(imidazolylmethyl)ferrocene. Their crystal structures revealed that these receptors are capable of incorporating anions such as PF(6)(-) and Br(-). Consequently, the anion binding studies were carried out using various techniques including electrochemistry (CV and OSWV), fluorescence, UV-vis, and (1)H NMR spectroscopy. All the receptors showed a special electrochemical response to the F(-) anion with a remarkable cathodic shift of more than 260 mV and displayed a unique selectivity for F(-) and AcO(-) anions with fluorescence enhancement over various other anions of present interest (Cl(-), Br(-), I(-), HSO(4)(-), H(2)PO(4)(-)). In addition, for receptor , obvious absorption changes were observed when the H(2)PO(4)(-) anion was added while other anions (F(-), Cl(-), Br(-), I(-), AcO(-), HSO(4)(-)) showed only a minor influence on the UV-vis spectra. (1)H NMR titrations demonstrated that receptors and can bind anions through (C-H)(+)X(-) hydrogen bonds and showed strong affinity and high selectivity for the AcO(-) anion in acetonitrile.     

Anion responsive TTF-appended calix[4]arenes. Synthesis and study of two different conformers

Two new cone- and 1,3-alternate-calix[4]arenes (cone-1 and 1,3-alt-1), bearing four modified TTF (tetrathiafulvalene) substituents on the upper rim, have been synthesized. The binding ability of these two sets of conformers for various anions, including F(-), Cl(-), Br(-), I(-), PF6(-), ClO4(-), HSO4(-), CH3COO(-), H2PO4(-), and HP2O7(3-), was tested in organic media by monitoring the changes in their UV/vis and (1)H NMR spectra as a function of added anion, as well as via cyclovoltammetry (CV) (all anions studied as their respective TBA salts). On the basis of the present findings, we propose that incorporation of four TTF units within an overall calix[4]arene-based recognition framework produces a preorganized receptor system that displays a modest preference for the pyrophosphate (HP2O7(3-)) anion.     

激光促进甲醇氧化偶联表面反应的规律

用沉淀法制备了Ｌｉ３ＰＯ４、ＢｉＰＯ４和Ｌｉ３ＰＯ４、ＢｉＰＯ４三种固体表面材料,并用ＸＲＤ、ＩＲ、ＴＰＤ和激光促进表面反应（ＬＳＳＲ）等技术研究了这些固体表面上甲醇氧化偶联生成乙二醇的反应规律。实验结果表明：甲醇在固体材料表面的Ｐ＝９键上产生Ｃ－Ｈ端的分子态吸附,在表面的Ｌｅｗｉｓ酸位（金属离子）上产生解离态吸附。Ｌｉ３ＰＯ４和ＢｉＰＯ４的相互作用可促进甲醇在固体表面上的分子态吸附而抑制解离态吸     

Very strong C-H...O, N-H...O, and O-H...O hydrogen bonds involving a cyclic phosphate.

Very short C-H...O, N-H...O, and O-H...O hydrogen bonds have been generated utilizing the cyclic phosphate [CH2(6-t-Bu-4-Me-C6H2O)2]P(O)OH (1). X-ray structures of (i) 1 (unsolvated, two polymorphs), 1...EtOH, and 1...MeOH, (ii) [imidazolium](+)[CH2(6-t-Bu-4-Me-C6H2O)2PO2](-)...MeOH [2], (iii) [HNC5H4-N=N-C5H4NH](2+)[(CH2(6-t-Bu-4-Me-C6H2O)2PO2)2](2-)...4CH3CN...H2O [3], (v) [K, 18-crown-6](+)[(CH2(6-t-Bu-4-Me-C6H2O)2P(O)OH)(CH2(6-t-Bu-4-Me-C6H2O)2PO2)](-)...2THF [4], (vi) 1...cytosine...MeOH [5], (vii) 1...adenine...1/2MeOH [6], and (viii) 1...S-(-)-proline [7] have been determined. The phosphate 1 in both its forms is a hydrogen-bonded dimer with a short O-H...O distance of 2.481(2) [triclinic form] or 2.507(3) A [monoclinic form]. Compound 2 has a helical structure with a very short C-H...O hydrogen bond involving an imidazolyl C-H and methanol in addition to N-H...O hydrogen bonds. A helical motif is also seen in 5. In 3, an extremely short N-H...O hydrogen bond [N...O 2.558(4) A] is observed. Compounds 6 and 7 also exhibit short N-H...O hydrogen bonds. In 1...EtOH, a 12-membered hydrogen-bonded ring motif, with one of the shortest known O-H...O hydrogen bonds [O...O 2.368(4) A], is present. 1...MeOH is a similar dimer with a very short O(-H)...O bond [2.429(3) A]. In 4, the deprotonated phosphate (anion) and the parent acid are held together by a hydrogen bond on one side and a coordinate/covalent bond to potassium on the other; the O-H...O bond is symmetrical and very strong [O...O 2.397(3) A].     

对苯二甲醛缩二氨基硫脲-钆配合物的合成及阴离子识别研究

合成了化合物(2E,2′E)-2,2′-(1,4-苯基双亚甲基双硫代氨基脲)(C10H12N6S2)(L),利用L与钆离子形成了配合物(GdL)。用UV-Vis吸收光谱考察其与F-、Cl-、Br-、I-、Ac-、NO3-、HSO4-和H2PO4-等阴离子的识别。研究表明,加入F-或H2PO4-时,溶液颜色由无色变为黄色,加入其它阴离子没有变化,从而实现受体对这两种阴离子的检测。Job法表明主客体间形成1∶1配合物。受体对两种离子的识别作用主要源于配合物多余的结合位点。在此基础上,以GdL的DMSO溶液作为起始状态,以F-和H2PO4-为两化学输入,构建了一个"或"(OR)分子逻辑门。     

A novel colorimetric sensor of dihydrogen-phosphate based on metal complex between 8-hydroxy quinoline-5-azo-4'-nitrobenzene and cobalt

A novel colorimetric sensor based on 8-hydroxy quinoline-5-azo-4'-nitrobenzene (1) was prepared and used for recognizing anions. 1 and its metal complex (1.Co) were found to show response to anions such as CH(3)CO(2)(-), H(2)PO(4)(-), HSO(4)(-), F(-) and dramatic color changes were observed. The selectivity and sensitivity of 1 and 1.Co for sensing anions were different, which was in the order of CH(3)CO(2)(-)>F(-)>H(2)PO(4)(-)>HSO(4)(-) for 1 and H(2)PO(4)(-)>HSO(4)(-)>CH(3)CO(2)(-) approximately F(-) for 1.Co, respectively. In CH(3)CN, sensor 1.Co exhibited excellent specificity toward H(2)PO(4)(-), and the color variety was dependent on the concentration of H(2)PO(4)(-) which was attributed to anion structure and stability of anionic complex (1-anion), metal complex (1-Co) and inorganic complex (Co-anion).     

Design and function of pre-organised outer-sphere amidopyridyl extractants for zinc(II) and cobalt(II) chlorometallates: the role of C-H hydrogen bonds

Four new sterically hindered pyridines, L(1)-L(4)-containing amido substituents at the 2-position act as efficient solvent extractants for [CoCl(4)](2-) or [ZnCl(4)](2-) from acidic chloride solutions through protonation of the pyridino N-centre to form the neutral outer-sphere complexes [(LH)(2)MCl(4)]. These ionophores show very high selectivity for chlorometallate anions over chloride ion and are readily stripped to liberate the free-metal chlorides without the formation of inner-sphere complexes [ML(2)Cl(2)]. Single-crystal X-ray structure determinations of [(L(2)H)(2)CoCl(4)] and [(L(2)H)(2)ZnCl(4)] (L(2) = 2-(4,6-di-tert-butylpyridin-2-yl)-N,N'-dihexylmalonamide) coupled with (1)H?NMR spectroscopy and DFT calculations on L(2)H(+) and other complexes of [ZnCl(4)](2-) confirm that the pyridinium NH group does not address the outer co-ordination sphere of the metallanion, but rather forms a hydrogen bond to the pendant amide groups and thus pre-organizes the ligand to present both C-H and amido N-H hydrogen-bond donors to the [MCl(4)](2-) ions. The selectivity for chlorometallates over chloride ions shown by this class of extractants arises from their ability to present several polarized C-H units towards the charge-diffuse ions [MCl(4)](2-), whereas the smaller, "harder" chloride anion prefers to be associated with the amido N-H hydrogen-bond donors.     

一类以光度法进行检测的新型阴离子敏感化合物

对6种带羟基的分子内电荷转移化合物(其中化合物1,4,5,6含氰基基团)及与不同阴离子间的相互作用及其分子识别进行了研究.发现化合物2,3,5,6均对F^-离子有优良的检测能力,并对H₂PO₄^-有一定的响应能力,其中化合物2对AcO^-离子也有一定的响应.对实验结果进行了初步讨论,并对提高敏感化合物的灵敏度和选择性提出了看法.     

Stabilization of isolated mixed-valence trimers in a novel nickel dithiolene complex with CF2 substituents

The preparation of the novel paramagnetic nickel dithiolene complex Ni(F2pdt)2-* (F2pdt2-: 2,2-difluoro-1,3-propanediyldithioethylene-1,2-dithiolate) and its X-ray crystal structure as n-Bu4N+ salt are described. (n-Bu4N)[Ni(F2pdt)2] (2) crystallizes in the orthorhombic system, space group Pna2(1) with a = 21.379(4) A, b = 8.9702(18) A, and c = 18.527(4) A. The radical anions are isolated from each other by the bulky n-Bu4N+ cations and exhibit a Curie-type magnetic behavior. Two reversible redox waves corresponding to the redox couples Ni(F2pdt)2(2-/-*) and Ni(F2pdt)2(-*/0) are observed at -0.55 and 0.30 V vs SCE, illustrating the electron withdrawing effect of the CF2 substituents. As a consequence, (TTF)3(BF4)2 oxidation of the radical anion does not afford the neutral Ni(F2pdt)2(0) but a TTF salt formulated as [TTF](3)[Ni(F2pdt)2]3[CH2Cl2]. It crystallizes in the triclinic system, space group P1 with a = 12.330(3) A, b = 12.726(3) A, c =15.706(3) A, alpha = 91.10(3), beta = 110.78(3), and gamma = 116.01(3). Donor and acceptor moieties are organized into (TTF)3(2+) and [Ni(F2pdt)2]3(2-) trimers whose dicationic and dianionic charges have been inferred from the intramolecular bond lengths evolution and the singlet-triplet magnetic behavior. These trimers arrange orthogonally to each other into chess-board-like slabs, characterized by a segregation of the CF2 fragments and further stabilized by weak C-H.F interactions. Extended Hückel calculations show that only the nickel dithiolene complex trimer actually contributes to the magnetic susceptibility.     

异丁烷部分氧化V-P-O/SiO2催化剂的研究

The V2O5/SiO2 and V2O5-P2O5/SiO2 catalysts were prepared by the Sol-gel method. The surface composition,structure,chemisorption and reactivity of the catalysts were systematically studied by using the techniques of XRD,TPR,IR,TPD and icro-reactor. The results showed that the active component was dispersed uniformly on the surface of amorphous SiO2 . There existed Lewis base sites（V=O and V-O-V）and Lewis acid sites （Vn+）on the surface of these catalysts. An addition of PO43- could lower the activity of surface terminal oxygen of Lewis base sites V=O. Iso-butane could chemisorbed on surface terminal oxygen of Lewis base sites V=O by one or two H atoms in -CH3 to form molecular adsorption states. Reaction products of i-C4H10 on the V-P-O/SiO2 catalyst were mainly i-C4H8,MAL,MAA and COx . Conversion of i-C4H10 was 5% and selectivity of partial oxidation products is above 72% at 300℃. The addition of PO43- could improve the selectivity of partial oxidation products on the VSiO catalyst because PO43- could reduce the activity of lattice oxygen in V = O bond,and weaken the adsorption intensity of i-C4H10 .     

Interaction between biphenols and anions: selective receptor for dihydrogenphosphate

Biphenol was shown to bind dihydrogenphosphate (H2PO4-) selectively over various other anions (MeCO2-, Cl-, Br-, I-, NO3-, HSO4-). The highly selectivity of biphenol toward dihydrogenphosphate is explained in terms of the basicity and shape of the guest anion.     

A Facile Synthesis of Ethyl 2,4-Dimethoxy-6-perfluoroalkyl-benzoates via Acyclic Precursors

Introduction Polysubstituted arenes are important intermediates in synthetic medicines and dyestuffs, and the fluorinated analogues are more attractive as a result of their lipo-philicity and the increment of activity.1,2 Therefore, to study the convenient and efficient synthesis of polysub-stituted arenes is valuable in organic synthetic method-ology. We have designed a simple synthesis of fluori-nated polysubstituted arenes through the intramolecular Wittig reaction of a new phosphorous ylid…     

Anion recognition and anion-mediated self-assembly with thiourea-functionalised fused [3]polynorbornyl frameworks

Three conformationally preorganised host molecules based on the [3]polynorbornyl framework and incorporating di-urea receptors were synthesised and their interaction with a series of anions investigated by (1)H NMR spectroscopy. A high affinity of each host molecule for dihydrogenphosphate (H(2)PO(4)(-)) and dihydrogenpyrophosphate (H(2)P(2)O(7)(2-)) was identified. In addition to binding to the urea receptors of the host molecules, evidence for an interaction involving the non-polar C-H groups within the binding cavity of the framework and guest anions was also discovered. Furthermore, an unusual 2 : 1 host-to-anion stoichiometry was indicated when binding H(2)P(2)O(7)(2-), and a model for the anion-mediated self-assembly of this complex species is proposed.     

Fluoride-selective colorimetric sensor based on thiourea binding site and anthraquinone reporter

A structurally simple colorimetric sensor, N-4-nitrobenzene-N'-1'-anthraquinone-thiourea (1), for anions was synthesized and characterized by (1)H NMR, ESI mass and IR methods. In acetonitrile, the addition of F(-) changed 1 solution from colorless to yellow. In the presence of other anions such as CH(3)CO(2)(-), H(2)PO(4)(-), HSO(4)(-) and Cl(-), however, the absorption spectrum of 1 was slightly red shifted with no obvious color changes observed. The association constants of anionic complexes followed the order of F(-)>CH(3)CO(2)(-)>H(2)PO(4)(-)>HSO(4)(-)>Cl(-)>Br(-), which was different from the order of anion basicity. AM1 calculation results indicated that the most stable configuration of 1 existed in the Z-E-conformation with a six-membered ring via intramolecular hydrogen bond. This made thiourea moiety of 1 in an unfavorable conformation to bond with oxygen-anionic substrates such as CH(3)CO(2)(-) and H(2)PO(4)(-), thus leading to a high selectivity and sensitivity for the detection of F(-).     

Na2WO4—H2O2酸体系催化氧化1—甲氧基—2—丙醇的研究

研究了Na2WO4-H2O2体系在催化氧化1-甲氧基-2-丙醇为甲氧基丙酮反应中的催化活性,发现酸助剂及添加物对甲氧基丙酮的收率有较大的影响。酸助剂中,NaHSO4对活性的促进作用最好;而H2PO4^-和HPO4^2-对体系的活性不利。极性小分子甲醇、乙腈可促进1-甲氧其-2-丙醇的氧化,提高甲氧基丙酮的收率。同时还考察了甲醇量对甲氧基丙酮收率的影响。     

香豆素衍生物对阴离子的识别特性

用紫外光谱滴定法研究了3种香豆素衍生物与阴离子间存在的特殊识别行为,比较了受体分子结构对阴离子配合物稳定性的影响,以及阴离子浓度对配合物光谱的影响.实验结果表明:受体分子对F^- 、Cl^-、Br^-、Ac^-、H₂PO₄^-、HSO₄^-等不同种阴离子客体的识别能力存在一定差异,受体分子与阴离子通过氢键结合,由于氢键良好的方向性和选择性,对F^-、Ac^-、H₂PO₄^-等有较好的选择性和识别能力,而与其他的阴离子几乎没有作用.