A novel colorimetric receptor responding AcO anions based on an azo derivative in DMSO and DMSO/water solution

A novel and efficient receptor based on the phenylhydrazone derivatives is successfully developed and applied to the acetate anion recognition, indicating that the origin of special preference for acetate (AcO⁻) anion maybe the structure well matching between the host and the guest. The sensor changes its color so obviously on addition of the acetate ions and that may make the naked-eye recognition in DMSO and even in DMSO/H₂O (95/5) solution come true. Also, the anion binding ability determinations were performed by UV-vis titration and ¹H NMR titration experiments with different anions in the solutions mentioned. The fluorescence enhancement can also be observed after the host is coordinated with the AcO⁻ anion and excited by light wavelength at 280 nm.     

基于含偶氮酚羟基席夫碱新型简单比色传感器

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H₂PO₄^-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.     

A turn-on fluorescent anion receptor based on N,N′-di-β-naphthyl-1,10-phenanthroline-2,9-diamide

A simple turn-on fluorescent anion chemosensor with amide moiety as binding sites was designed, synthesized and characterized. Binding ability of the receptor 1 with anions was evaluated through the fluorescence titration in DMSO and the ¹H NMR titration in DMSO-d₆ and coordination of anions to 1 led to a visible enhancement in fluorescence intensity. The fluorescence enhancement could be explained on the basis of two signaling transduction mechanisms: (1) inhibition of a photoinduced electronic transfer (PET) mechanism and (2) anion-induced increase of the rigidity of the host molecules. In addition, the results of ¹H NMR titrations suggested that a host-guest hydrogen-bonding complex with an association constant K_ass=7379 mol⁻¹ L was formed between 1 and F⁻ and the mode of host-guest interactions was provided.     

Synthesis and Chiral Recognition Properties of Novel Fluorescent Chemosensors for Amino Acid

The charge neutral chiral optical sensors 1a∼d containing thiourea and amide groups were synthesized by simple steps in good yields and their structures were characterized by IR, ¹H NMR, ¹³C NMR, MS spectra and elemental analysis. The enantioselective recognition for α-phenylglycine and phenylglycinol was examined by fluorescence emission and UV-vis spectra. The fluorescence and UV-vis spectra changes of 1a were obvious when the enantiomers of α-phenylglycine anion were added, which exhibited that 1a has good enantioselective recognition ability towards α-phenylglycine. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Quinoline-Based “On-Off” Fluorescent Sensor for Acetate: Effect of Link Mode between Binding Sites and Fluorophore on Fluorescence Changes

ABSTRACT

A novel colorimetric and fluorescence anion sensor based on 8-nitroquinolyl-2-aldehyde phenyl-thiosemicarbazone (1) was designed and synthesized according to the approach that the binding sites were covalently linked to the signaling units. In DMSO, sensor 1 exhibited a naked-eye color change from colorless to yellow upon complexation with acetate. The association constant of 1 for acetate ion was determined to be 1.20 × 10³ M^?1 by nonlinear fitting analyses of the titration curves. The strong interactions of compound 1 with acetate ion could be rationalized on basis of not only the guest basicity but also shape complementarity between 1 and acetate. In addition, the fluorescence emission of 1 was effectively quenched upon addition of acetate ions owing to the fact that the photoinduced electron transfer (PET) was enhanced.     

The interaction between inorganic Li salts (LiTf,LiNTf2) and the surface of alumina particles as studied with solid state nuclear magnetic resonance

The interaction between Li salts {LiTf (Tf = CF₃SO₃) and LiNTf₂ (NTf₂ = N(SO₂CF₃)₂)} with surface modified alumina particles (basic, neutral or acidic) is investigated employing a range of advanced solid state NMR methodologies. Utilizing ⁷Li MAS NMR, a new signal – in addition to the signal of the pure salt – could be identified in the composite samples, increasing with increasing basicity of the alumina surface. Employing ⁷Li–{¹H} CPMAS NMR and ⁷Li–{¹H}–CPMAS–{²⁷Al} REAPDOR NMR spectroscopy, this new signal could be unequivocally assigned to an alumina-surface bound Li species. For the anions, ¹⁹F MAS NMR spectra clearly prove the existence of new anion sites. Employing ¹⁹F–{⁷Li} REDOR spectroscopy and ¹⁹F–{²⁷Al} TRAPDOR NMR spectroscopy, the identified signals could be safely assigned to anions within the pristine Li salt and anions attached to the alumina surface. These results present direct evidence for the anion???alumina surface and cation???alumina surface interaction, suggested by several authors to aid in the interpretation of the effect of the ceramic additive on the ionic conductivity.     

The triel bond: a potential force for tuning anion–π interactions

Using ab-initio calculations, the mutual influence between anion–π and B···N or B···C triel bond interactions is investigated in some model complexes. The properties of these complexes are studied by molecular electrostatic potential, noncovalent interaction index, quantum theory of atoms in molecules (QTAIM) and natural bond orbital (NBO) analyses. According to the results, the formation of B···N or B···C triel bond interactions in the multi-component systems makes a significant shortening of anion–π distance. Such remarkable variation in the anion–π distances has not been reported previously. The strengthening of the anion–π bonding in the multi-component systems depend significantly on the nature of the anion, and it becomes larger in the order Br^? > Cl^? > F^?. The parameters derived from the QTAIM and NBO methodologies are used to study the mechanism of the cooperativity between the anion–π and triel bond interactions in the multi-component complexes.     

Photoelectron-spectroscopic determination of lattice self-potentials in lanthanide trifluorides

Since the photoelectron spectroscopically measured binding energies probe the potentials at the cation and anion sites separately in solids, they should be a direct determination of the lattice self-potentials at these sites through comparisons with the respective ionization potentials of the gaseous ions. In a study of the photoionization of the 1s orbital electrons on the fluoride ion and of the outer 5p or 4f orbital electrons on the cations of the lanthanide trifluorides, it is found that the so determined lattice self-potentials at the anion sites deviate from those calculated from the electrostatic interactions in the point charge model by an amount which can be explained in terms of ionicity. For the cations, however, the deviations for all except La³⁺ and perhaps Gd³⁺ exceed those expected for ionicity in the point charge model by as much as 2.3 eV in the case of the maximum at Pr³⁺. These deviations are discussed in terms of crystal field interactions, covalency, polarization, and complication caused by final state relaxation during photoionization.     

An NMR investigation of the existence of halide and carboxylate co‐solute effects on the rotational barrier about the C?N bonds in urea and thiourea

Rotational barriers of the NH₂ group in thiourea and benzylurea in solution become slightly larger in the presence of anionic hydrogen‐bond acceptors. The interactions between the N? H bond and different anions were investigated in acetonitrile solution using ¹H{¹⁴N} variable‐temperature NMR. Line‐shape analyses of the spectra show a weakly anion‐dependent increase in ΔG^? of rotation, with benzoate having the strongest effect and iodide the weakest. Hydrogen‐bonding acidities of benzylurea and thiourea were also measured on the Abraham solute hydrogen‐bond acidity scale by proton NMR. Copyright © 2010 John Wiley & Sons, Ltd.     

Investigation of the magnetic properties of the Fe2-xCrxCaO4 system

Conclusions Due to the fact that the iron ions in two neighbouring elementary cells along the c-axis are in symmetry positions in relation to the oxygen anion (through which the interaction with other iron ions is achieved), the stronger 120° and 130° interactions could be considered as interactions not by zigzag-formed chains, but by the folded planes with c-axis as a generant, i.e., the quasi-twodimensional magnetic properties are evinced in Cr_xFe_2–xCaO₄.     

Investigation of cation–anion interaction in 1‐(2‐hydroxyethyl)‐3‐methylimidazolium‐based ion pairs by density functional theory calculations and experiments

Gas‐phase structure, hydrogen bonding, and cation–anion interactions of a series of 1‐(2‐hydroxyethyl)‐3‐methylimidazolium ([HOEMIm]⁺)‐based ionic liquids (hereafter called hydroxyl ILs) with different anions (X = [NTf₂]^–, [PF₆]^–, [ClO₄]^–, [BF₄]^–, [DCA]^–, [NO₃]^–, [AC]^– and [Cl]^–), as well as 1‐ethyl‐3‐methylimizolium ([EMIm]⁺)‐based ionic liquids (hereafter called nonhydroxyl ILs), were investigated by density functional theory calculations and experiments. Electrostatic potential surfaces and optimized structures of isolated ions, and ion pairs of all ILs have been obtained through calculations at the Becke, three‐parameter, Lee–Yang–Parr/6‐31 + G(d,p) level and their hydrogen bonding behavior was further studied by the polarity and Kamlet–Taft Parameters, and ¹H‐NMR analysis. In [EMIm]⁺‐based nonhydroxyl ILs, hydrogen bonding preferred to be formed between anions and C2–H on the imidazolium ring, while in [HOEMIm]⁺‐based hydroxyl ILs, it was replaced by a much stronger one that preferably formed between anions and OH. The O–H···X hydrogen bonding is much more anion‐dependent than the C2–H···X, and it is weakened when the anion is changed from [AC]^– to [NTf₂]^–. The different interaction between [HOEMIm]⁺ and variable anion involving O–H···X hydrogen bonding resulted in significant effect on their bulk phase properties such as ¹H‐NMR shift, polarity and hydrogen‐bond donor ability (acidity, α). Copyright © 2011 John Wiley & Sons, Ltd.     

Revisited vibrational assignments of imidazolium‐based ionic liquids

Imidazolium‐based ionic liquids (ILs) involving anions of variable coordinating strength have been investigated using infrared (IR) and Raman spectroscopies, density functional theory (DFT) calculations and selective deuteration of the imidazolium CH groups. Particular emphasis has been placed on the vibrational assignments of the anion and cation internal vibrations, a prerequisite before any interpretation of spectral changes due to ion–ion interactions in these unconventional liquids. The vibrations of highly symmetric and weakly coordinating anions, such as PF₆⁻, have unperturbed wavenumbers, but unexpected IR or Raman activity for some modes, showing that the anion is subjected to an anisotropic electric field. The stretching as well as the in‐plane and out‐of‐plane bending modes of the imidazolium CH groups are anharmonic. They give broad bands that reflect a large distribution of interactions with the surrounding anions. All the bending modes are mixed with ring vibrations and the stretching modes are complicated by Fermi resonance interactions with overtones and combination of in‐plane ring modes. However, the stretching vibration of the quasi‐diatomic C₍₂₎ D bond appears to be a good spectroscopic probe of the increasing cation–anion interactions when the coordinating strength of the anion increases. The broad absorption observed in the far IR with weakly coordinating anions remains practically unchanged when the acidic C₍₂₎ H imidazolium bond is methylated and even when the imidazolium cation is substituted by tetra‐alkyl ammonium or pyrrolidinium cations. It is concluded that this absorption is a general feature of any IL, coming from the relative translational and librational motions of the ions without needing to invoke C₍₂₎ H anion hydrogen bonds. Copyright © 2010 John Wiley & Sons, Ltd.     

The role of F A1:Ag+ defects in laser light generation and coadsorption of CO and halogen atoms at the KCl and KBr surface sites. First principles calculations

F _A1:Ag⁺ color center at the low coordination (100) and (110) surface sites of KCl and KBr thin films play an important role in providing tunable laser oscillation and adsorbatesubstrate interactions. Double-well potentials at this site are investigated using ab initio molecular electronic structure calculations. The calculated Stokes shifted (optical transition bands), opticaloptical conversion efficiencies, the probability of orientational destruction, exciton (energy) transfer and Glasner-Tompkins empirical rule suggest that laser light generation is sensitive to (i) the lattice anion, (ii) the coordination number of surface ions, and (iii) the choice of the basis set centered on the anion vacancy. The adsorbate-substrate interactions were found to be dependent on the electronegativity of the adatom and on the lattice anion. Optimised geometries and the coadsorption of CO and (F, Cl, Br, I) on KCl and KBr (100) crystals are presented. Calculated chemisorption energies for CO on the (halogen atom/defect free sites of KCl and KBr (100) crystals) showed that the coadsorption of halogen atom tends to block other adsorbate-substrate interactions at the nearest neighbour sites. Thus if halogen atom coverage increases, the CO prefers to be adsorbed on the K⁺ site of the KCl and KBr (100) surfaces and on KBr relative to KCl.      

Bulk electrolysis of Zn-phthalocyanine unveils self assembled nanospheres via anion binding

Stimuli responsive π-conjugated macrocyclic systems has shown significant attention in organic electronics, however, amongst them, porphyrins and phthalocyanines unveiled remarkable growth towards materials and biological applications. Herein, we report bulk electrolysis of Zn-phthalocyanine system (ZnPc-OMe) under potential difference of 1.5 V in chloroform results anion binding mechanism directs the formation of self-assembled nanospheres by diffusion controlled approach. Electrochemical and UV–Vis absorption studies of ZnPc-OMe suggest that anion (Cl⁻) binding ability towards ‘Zn‘ whilst applied potential leads to the formation of H⁺[(Cl)ZnPc-OMe]^- promote the enhanced current and charge generation. Microscopic analysis revealed that ZnPc-OMe and H⁺[(Cl)ZnPc-OMe]^- exhibit the nanosheets and spheres with an average diameter of 0.5–1 μm and 300–500 nm, respectively. Powder X-ray diffraction analysis and raman spectra revealed the changes in crystalline phase transitions via ion-dipole and π-π stacking interactions. Thus, these unique features are atypical for phthalocyanine derivative hitherto unknown.     

Three-dimensional organometallic thallium(I) supramolecular polymer nanostructures synthesized with sonochemical process

A new three-dimensional thallium(I) supramolecular polymer, [Tl₂(μ₂-ATA)]_n (1), [H₂ATA = 2-aminoterephthalic acid]_, has been synthesized and characterized. The single-crystal X-ray data of compound 1 shows one type of Tl^I ion with a low coordination number. Compound 1 was self-assembled from Tl⋯C, Tl⋯O and Tl⋯N secondary interactions in thallium(I) coordination and the active lone pair on Tl^I in this compound may be involved in donor bonding. Two sides of the aromatic ring of ATA²⁻ anion have been involved in two types of secondary Tl⋯C approaches. Three samples of 1 were synthesized with three different concentrations of initial reagents under ultrasonic irradiation. The thermal stability of compound 1 samples were studied by thermo gravimetric (TG) and differential thermal analyses (DTA). These nano-structures were characterized by X-ray powder diffraction (XRD) and scanning electron microscopy (SEM).     

Design of Two Pyrazole-Based Sensors with Similar Configuration and Different Fluorescent Response to Anions

Two simple fluorescent anion receptors based on 1-phenyl-3-methylpyrozole-5-one-4-one phenylhydrazone (L1) and 1-phenyl-3-methylpyrozole-5-one-4-one p-nitrophenylhydrazone (L2) were designed, synthesized and characterized with ¹H NMR, COSY spectrum, ¹³C NMR, ESI-mass and elemental analyse. Interestingly, two receptors with similar configuration exhibited different anion binding behaviors in DMSO solution. The results of Job plots and ESI-mass spectrum indicate that L1 bind anions such as F⁻, AcO⁻, H₂PO₄⁻ to form 2:1 host-guest complexation, while L2 bind anions to form 1:1 host-guest complexation in the solution.     

Infrared spectroscopic and conductivity studies of poly(N-methylpropylenimine)/lithium triflate electrolytes

Poly(propylenimine), PPI, was methylated using Eschweiler-Clark conditions to produce poly(N-methylpropylenimine), PMPI. Differences may be seen in the IR spectra of the PMPI (–CH₂CH₂CH₂NCH₃–) and its homolog poly(N-methylethylenimine), PMEI, (–CH₂CH₂NCH₃–), especially in the conformation region (~ 1100 to ~ 1400 cm^− 1). The addition of lithium trifluoromethanesulfonate, (LiCF₃SO₃), sharpens the distinctions between these systems. Comparison of IR spectra of polymer:LiCF₃SO₃ complexes at compositions ranging from pure polymer to 5:1 N:Li⁺ (molar ratio) suggests significant differences in the nature of polymer salt interactions and the complex structure present in each system. These are further evidenced by differential scanning calorimetry data in which PMPI displays less variation in glass transition temperature, T_g, with the addition of salt than seen in PMEI. These observations may be interpreted in terms of local structural changes originating in cation–anion and cation–polymer interactions, particularly at mid to high salt concentrations.     

Theoretical study on cooperative interplay between anion–π and chalcogen-bonding interactions

The mutual influence between anion–π and chalcogen bond interactions is studied by ab initio calculations at the MP2/6-311++G^** level of theory. These effects are analysed in detail in terms of the structural, energetic, charge-transfer and electron density properties of the complexes. Interesting cooperativity effects are found when anion–π and chalcogen-bonding interactions coexist in the same complex. The effect of anion–π on the properties of chalcogen bonding is larger than that of chalcogen bonding on the properties of anion–π. The cooperative mechanism is analysed in terms of the electrostatic potentials, orbital interaction and electron density analysis.     

Fluorescence Turn on Sensor for Sulfate Ion in Aqueous Medium Using Tripodal-Cu2+ Ensemble

We report the selective recognition of sulfate anion in aqueous medium at biological pH 7.2 over the other interfering anions based on naphthoic acid bearing tripodal ligand by applying fluorescence turn off-on mechanism. The carboxylic acid groups in the ligand enhance the solubility in water and enable it to form complex with copper salt. Thus formed L-Cu²⁺ ensemble quench the fluorescence of the parent ligand and in turn recognize sulfate anion via revival of fluorescence intensity. The 1:2 stoichiometry was confirmed by ESI mass spectral data and Job’s plot. The average binding constant was found to be 6.2?×?10⁸ M^?2.