A sandwich anion receptor by a BODIPY dye bearing two calix[4]pyrrole units

A novel dicalix[4]pyrrolyl-substituted 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) dye I with an absorption peak at approximately 670 nm and an emission peak at about 690 nm was prepared. As an anion receptor, I displayed a red shift in absorption spectra and fluorescence quenching in varying degrees in the presence of F⁻, AcO⁻, H₂PO₄⁻, or Cl⁻. Compared with the parent calix[4]pyrrole, a representative anion receptor, I exhibited a stronger affinity to these anions due to the formation of a sandwich complex through multiple hydrogen-bonding interactions.     

Tysonite-type solid solutions in the BiF<Subscript>3</Subscript>-BiOF-BaF<Subscript>2</Subscript> system: Polymorphism and anionic conductivity

Tysonite solid solutions Bi_1−x Ba _x O _y F_3−x−2y in the BiF₃-BiOF-BaF₂ system were obtained by solid-phase synthesis in sealed copper tubes in an argon atmosphere at 873 K with subsequent quenching. The solid solutions were studied by X-ray diffraction, electron diffraction, and impedance spectroscopy. On the basis of X-ray powder diffraction data, the homogeneity ranges of the tysonite solid solutions were determined and the scheme of their location in the BiF₃-BiOF-BaF₂ system at 873 K was suggested. Aliovalent substitutions in both the cation and anion sublattices Ba²⁺ → Bi³⁺ and O²⁻ → F⁻ made it possible to vary the concentration of anion vacancies. It was found that, at a high concentration of anion defects at 873 K, the hexagonal tysonite modification with space group P6₃/mmc is stable. With a decrease in the defect concentration, the trigonal tysonite modification with space group $ P\bar 3c1 $ P\bar 3c1 becomes stable. An ordered monoclinic tysonite-type modification BiO _y F_{3 − 2y} (0.13 < y < 0.23) was revealed. For the homogeneity ranges of all tysonite phases, dependences of the unit cell parameters and conductivity on the composition along the sections with a constant barium or oxygen content were reported. The most probable location of oxygen anions and anion vacancies in the tysonite structure is discussed.     

Kinetic and mechanism of alkene polymerization

Triphenylmethyl salts of the very weakly-coordinating borate anions [CN{B(C₆F₅)₃}₂]⁻ (1), [H₂N{(C₆F₅)₃}₂]⁻ and [M{CNB(C₆F₅)₃}₄]²⁻ (M = Ni, Pd) have been prepared in simple one-pot reactions. Mixtures of (SBI)ZrMe₂/1/AlBu ₃ ⁱ (SBI = rac-Me₂Si(Ind)₂) are 30–40 times more active in ethylene polymerizations at 60–100°C than (SBI)ZrCl₂/MAO. The quantification of anion effects on propene polymerization activity at 20°C gives the order [CN{B(C₆F₅)₃}₂]⁻ > [H₂N{(C₆F₅)₃}₂]⁻ ≈ B(C₆F₅) ₄ ⁻ ≫ [MeB(C₆F₅)₃]⁻. The highest productivities were of the order of ca. 3.0 × 10⁸ g PP (mol Zr)⁻¹ h⁻¹ [C₃H₆]⁻¹, about 1.3–1.5 times higher than with B(C₆F₅) ₄ ⁻ as the counter anion. The titanium system CGCTiMe₂/1/AlBu ₃ ⁱ gave activities that were very similar to the zirconocene catalyst. The concentration of active species [C*] as determined by quenched-flow kinetic techniques indicates typical values of around 10%, independent of the counter anion, for both the borate and MAO systems. Pulsed field-gradient spin echo and nuclear Overhauser effect NMR experiments on systems designed to be more realistic models for active species with longer polymeryl chains, (SBI)M(CH₂SiMe₃)(μ-Me)B(C₆F₅)₃ and [(SBI)MCH₂SiMe ₃ ⁺ ...B(C₆F₅) ₄ ⁻ ] (M = Zr, Hf), demonstrated the influence of bulky alkyl chains on the ion pair solution structures: while the MeB(C₆F₅)₃ compound exists as a simple inner-sphere ion-pair, the B(C₆F₅) ₄ ⁻ compound is an outer-sphere ion pair (OSIP), a consequence of the relegation of the anion into the second coordination sphere by the γ-agostic interaction with the alkyl ligand. The OSIP aggregates to ion hextuples (10 mM) or quadruples (2 mM). Implications for the polymerization mechanism are discussed; the process follows an associative interchange (I _a) pathway. The text was submitted by the authors in English.     

Highly symmetrical phthalocyanines and perfluorophthalocyanines: The quantum-chemical study

By the quantum-chemical method (U)B3LYP/6-31G(d ₅,p) are determined point symmetry group (D _4h ) and equilibrium structure of phthalocyanine (PcH₂), phthalocyaninates PcBe, PcMg, PcCo, PcNi, PcCu, PcZn, perfluorophthalocyaninates ^FPcNi, ^FPcCu, ^FPcZn, cations Pc⁺Mt, ^FPc⁺Mt and anion PcCo⁻. In the approximation (U)B3LYP/6-311++G(3d ₅ f ₇,p)//6-31G(d ₅,p) is achieved the satisfactory accuracy of the calculation of ionization potentials of the studied molecules. Effect of nuclear relaxation at the ionization is 0.07±0.06 eV; correction for “zero” vibrations does not exceed 0.01 eV. Perfluorination increases ionization potentials by 0.7–0.8 eV.     

Hypercoordinate atoms of second-row elements in dodecahedrane endohedral complexes

The energy characteristics and geometric parameters of the dodecahedrane endohedral complexes X@C₂₀H₂₀ (X = C⁴⁻, N³⁻, O²⁻, F⁻, Ne) were studied by the density functional theory B3LYP method with the 6-311G(d,p), 6-311+G(d,p), and 6-311G(df,p)) basis sets. In all structures the central atoms X are characterized by a coordination number of 20. The energy of formation of the complexes decreases in the order X = C⁴⁻, N³⁻, O²⁻, F⁻, Ne. The coordination number of the central atom remains unchanged upon adding Li⁺ counterions to anionic systems. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 824–830, May, 2007.     

The structure of deprotonated tri-alanine and its <Emphasis Type="Italic">a</Emphasis><Stack><Subscript>3</Subscript><Superscript>−</Superscript></Stack> fragment anion by IR spectroscopy

We present the first infrared spectra of a mass-selected deprotonated peptide anion (AlaAlaAla) and its decarboxylated fragment anion formed by collision induced dissociation. Spectra are obtained by IRMPD spectroscopy using an FTICR mass spectrometer in combination with the free electron laser FELIX. Spectra have been recorded over the 800–1800 cm⁻¹ spectral range and compared with density functional theory calculated spectra at the B3LYP/6-31++G(d,p) level for different isomeric structures. These experiments suggest a carboxylate anion for [M-H]⁻ and an amide deprotonated (amidate) structure for the a ₃ fragment anion [M-H-CO₂]⁻. The frequency for the amidate carbonyl stretch occurring around 1555±5 cm⁻¹ has been confirmed by additional spectroscopic studies of the conjugated base of N-methylacetamide, which serves as a simple model system for the deprotonated amide linkage in a peptide anion.     

Measurement of the rate constants of the reactions of the chlorine atom with C<Subscript>3</Subscript>F<Subscript>7</Subscript>I and CF<Subscript>3</Subscript>I using the resonance fluorescence of chlorine atoms

The rate constants of the reactions of the chlorine atom with C₃F₇I (k ₁) and CF₃I (k ₂) have been measured using the resonance fluorescence of chlorine atoms in a flow reactor at 295 K: k ₁ = (5.2 ± 0.3) × 10⁻¹² cm³ molecule⁻¹ s⁻¹ and k ₂ = (7.4 ± 0.6) × 10⁻¹³ cm³ molecule⁻¹ s⁻¹. No iodine atoms have been detected in the reaction products.     

Adsorption of acridine yellow G from aqueous solutions using functionalized graphene nanoplatelets/modified polybutadiene hybrid composite

This paper presents an analysis of adsorption of acridine yellow G (AYG) from aqueous solutions through the use of functionalized grapheme nanoplatelets/modified polybutadiene hybrid composite (FGNPs/MPB). The adsorption of AYG onto FGNPs/MPB was investigated based on the AYG concentration, pH, contact time, temperature, and adsorbent dose. A maximum adsorption capacity was obtained at a pH of 7 (23.7 mg/g), an adsorbent dose of 1.0 g/L (20.8 mg/g), and an initial AYG concentration of 28.5 mg/L (16.9 mg/g). The value of q_e of FGNPs/MPB increases with an increase in temperature from 293 to 323 K. Equilibrium isotherm data were analyzed using the Langmuir and Freundlich isotherm models. The Langmuir model best describes the adsorption processes of AYG, which showed that the monolayer adsorption capacity of FGNPs/MBP is 22.9 mg/g. The pseudofirst-order, pseudosecond-order, and intraparticle diffusion models were used to study the kinetics of the AYG adsorption onto FGNPs/MPB. The pseudosecond-order model better described kinetic data for the adsorption of AYG onto FGNPs/MPB. Thermodynamic parameters, such as the Gibbs free energy, enthalpy, and entropy, indicated that the AYG adsorption onto FGNPs/MPB was spontaneous feasible, and endothermic.     

Structure and stability of oligomeric anions [M n X3 n + 1]? (M = Al, Ga, In; X = F, Cl, Br, I; n = 2–4): A quantum-chemical study

The structural and thermodynamic properties of oligomeric anions [M _n X_{3n+ 1}]⁻ (M = Al, Ga, In; X = F, Cl, Br, I; n = 2, 3, 4) have been obtained by the density functional theory B3LYP method with the LAN2DZ(d) and LAN2DZ(d)+ basis sets. A wide diversity of structural isomers was found for trimeric fluoride anions M₃F₁₀⁻. Among the trimers, except In₃F₁₀⁻, the most stable is a linear isomer composed of two MX₃ molecules coordinated to the MX₄⁻ anion. The formation of tetrameric anions M₄X₁₃⁻ was demonstrated to be thermodynamically allowed at low temperatures at MX₃: X⁻ > 4: 1. The existence of higher oligomers is less probable. The affinity of oligomer halides (MX₃) _n for halide ions increases with an increase in n. The propensity to form oligomeric anions decreases in the series F > Cl ≥ Br > I. The fluoride systems show a tendency to form structures with CN = 5 and 6, these structures for In being the most stable. Original Russian Text ? A.Yu. Timoshkin, 2009, published in Zhurnal Neorganicheskoi Khimii, 2009, Vol. 54, No. 1, pp. 87–100.     

Amidocrownophanes as Anion Receptor

Crownophanes composed of 28-membered ring atoms having two hydroxy groups, two amide groups, and aromatic parts such as naphthalene rings and either pyridine or benzene ring, can bind anions with high affinity and selectivity. The anion-coordination ability of these species has been observed by ¹H NMR techniques. As anion guest molecules, we selected some halides, dihydrogenphosphate and acetate ions. It has been found that amidocrownophanes, 3 and 4, can recognize anions in the order;H₂PO ₄ ⁻ >F⁻>CH₃COO⁻>Cl⁻>>Br⁻ and I⁻, while not only 1, 2, and 5 having no hydroxy group but also 6 having 27-membered ring have no ability for anion recognition under the same conditions. In order to exhibit the recognition ability for anion receptor, plural amide groups, hydroxy groups, and m-phenylene or 1,6-pyridyl rigid part play an important role in this macrocyclic system.     

The anion binding properties of neutral receptors bearing nitro group,phenanthroline or ruthenium(II) metal

A series of neutral cyclohexadiamine anion receptors containing nitro, phenanthroline or ruthenium(II) have been designed and synthesized. Their u.v.–vis spectroscopy investigations reveal that the receptor bearing nitro group displays the strongest affinities for F⁻, AcO⁻, H₂PO ₄ ⁻ and can be used as an efficient detection tool for the above anions. Results indicate that the anion affinities can be enhanced through appending nitro group and ruthenium(II) metal compared with phenanthroline moiety.     

Phenanthroline complexes bearing diamide-anion recognition sites

The synthesis and anion binding properties of new ruthenium(II) and cobalt(II) phenanthroline complexes, containing two amide subunits are described. Evidence for anion binding in dimethyl sulfoxide (DMSO) solution was obtained from u.v.–vis titration experiments. Results indicated that these receptors showed strong affinity for F⁻ and AcO⁻, and showed weak affinity for OH⁻ and H₂PO ₄ ⁻ , and showed no affinity for Cl⁻, Br⁻, I⁻. These receptors interacted with various anions examined through hydrogen-bond formation.     

A theoretical investigation on structures of tripodal thiourea derivatives and their anion recognition

The structural geometries of three tripodal thiourea receptors, i.e. 1,3,5-triethyl-2,4,6-tris[(N′-methylthioureido)methyl]benzene (1), tris[N′-methyl-N-(2-aminoethyl)thiourea]methane (2), tris[N′-methyl-N-(2-aminoethyl)thiourea]amine (3), and their complexes with F⁻, Cl⁻, Br⁻, I⁻, NO₃ ⁻, CO₃ ²⁻, SO₄ ²⁻, HSO₄ ⁻, PO₄ ³⁻, HPO₄ ²⁻ and H₂PO₄ ⁻ were obtained using the density functional theory calculations. Electronic and thermodynamic properties of anion binding complexes of the receptors 1, 2 and 3 were investigated. Recognition abilities of all the receptors in terms of selectivity coefficients are reported. Intermolecular interactions in all the studied complexes occurring via multi-point hydrogen bonding were found. The receptors 1, 2 and 3 were found to be excellent selectivity for phosphate ion and their binding free energy for the phosphate ion are −292.57, −291.77 and −295.01 kcal/mol, respectively.     

Voltammetry of electroactive liquid redox systems: anion insertion and chemical reactions in microdroplets of para-tetrakis(6-methoxyhexyl) phenylenediamine, para- and meta-tetrahexylphenylenediamine

The effect of the structure of the organic precursor molecule on the electroinsertion of anions and on the formation of materials in the ionic liquid state is compared for three compounds, para-N, N, N′, N′-tetrahexylphenylenediamine (p-THPD), meta-N, N, N′, N′-tetrahexylphenylene diamine (m-THPD), and para-N, N, N′, N′-tetrakis(6-methoxyhexyl)phenylenediamine (p-TMHPD), by characterising their condensed phase voltammetric properties in aqueous media. The electrochemically driven anion insertion in p-THPD and p-TMHPD in the presence of ClO₄ ⁻, F⁻, Cl⁻, Br⁻, I⁻, and SO₄ ²⁻ is shown to be extremely sensitive to structure. The introduction of the methoxy end groups in p-TMHPD causes (1) a considerable shift to more negative electroinsertion potentials, (2) a less stable response which upon continuous cycling decreases, and (3) considerably lower anion selectivity. For the insertion of sulfate, only p-TMHPD yields an electrochemical response which is shown to be consistent with insertion of the dianion SO₄ ²⁻. The electrochemical oxidation of a deposit of m-THPD is accompanied by anion insertion and a chemical reaction step in an EC-type electrochemical process. The product of the chemical step is electrochemically active and results in a new reversible electroinsertion process. Starting materials and products of the microdroplet reactions are characterised by Maldi-TOF mass spectrometry and a reaction mechanism based on condensed phase polymerisation is proposed. Received: 15 November 1999 / Accepted: 2 December 1999     

A Laccase of <Emphasis Type="Italic">Fomes durissimus</Emphasis> MTCC-1173 and Its Role in the Conversion of Methylbenzene to Benzaldehyde

A laccase has been purified from the liquid culture growth medium containing bagasse particles of Fomes durissimus. The method involved concentration of the culture filtrate by ultrafiltration and anion exchange chromatography on diethyl aminoethyl cellulose. The sodium dodecyl sulphate–polyacrylamide gel electrophoresis (SDS-PAGE) and native polyacrylamide gel electrophoresis both gave single protein band indicating that the enzyme preparation was pure. The molecular mass of the purified laccase determined from SDS-PAGE analysis was 75 kDa. Using 2,6-dimethoxyphenol as the substrate, the determined K _m and k _cat values of the laccase are 182 μM and 0.35 s⁻¹, respectively, giving a k _cat/K _m value of 1.92 × 10³ M⁻¹ s⁻¹. The pH and temperature optimum were 4.0 and 35 °C, respectively. The purified laccase has yellow colour and does not show absorption band around 610 nm found in blue laccases. Moreover, it transformed methylbenzene to benzaldehyde in the absence of mediator molecules, property exhibited by yellow laccases.     

Special characteristics of fluorescence and resonance Rayleigh scattering for cadmium telluride nanocrystal aqueous solution and its interactions with aminoglycoside antibiotics

CdTe nanocrystals (CdTe NCs) were achieved by reaction of CdCl₂ with KHTe solution and were capped with sodium mercaptoacetate. The product was detected by transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), energy dispersive spectroscopy (EDS), fluorescence spectra, ultraviolet-visible spectra and X-ray diffraction (XRD). The CdTe NCs are of cubic structure and the average size is about 5 nm. The fluorescence quantum yield of CdTe NCs aqueous solution increased from 37% to 97% after 20 d under room light. The maximum λ _em of fluorescence changed from 543 nm to 510 nm and the blue shift was 33 nm. CdTe NCs aqueous solution can be steady for at least 10 months at 4 in° a refrigerator. The resonance Rayleigh scattering (RRS) of CdTe NCs in the aqueous solution was investigated. The maximum scattering peak was located at about 554 nm. The interactions of CdTe NCs with amikacin sulfate (AS) and micronomicin sulfate (MS) were investigated respectively. The effects of AS and MS on fluorescence and RRS of CdTe NCs were analyzed. It was found that AS and MS quenched the photoluminescence of CdTe NCs and enhanced RRS of CdTe NCs. Under optimum conditions, there are linear relationships between quenching intensity (F ₀-F), intensity of RRS (I-I ₀) and concentration of AS and MS. The detection limits (3б) of AS and MS are respectively 3.4 ng·mL⁻¹ and 2.6 ng·mL⁻¹ by the fluorescence quenching method, and 15.2 ng·mL⁻¹ and 14.0 ng·mL⁻¹ by the RRS method. The methods have high sensitivity, thus CdTe NCs may be used as fluorescence probes and RRS probes for the detection of aminoglycoside antibiotics. Supported by the National Natural Science Foundation of China (Grant No. 20475045)     

The fluoride content of an anion exchange resin in the fluoride form. Determinations using18F as a tracer

The fluoride content of an anion exchange resin in the F⁻-form depends on the material of the equipment used for the preparation. If a glass equipment is used too much fluorine is introduced, but in a teflon equipment the fluoride content is exactly as expected. The experimental results are explained by taking into account a competition of F⁻ and SiF ₆ ⁻² for the hydroxyl positions of the resin(OH⁻).     

The structure of a new octahedral fluoride complex of niobium (Me4N)2[Nb6F6Br6(H2O)2Cl4]·6H2O

The substitution reaction of thiocyanide groups of the complex K₄[Nb₆F₆Br₆(NCS)₆] in aqueous hydrochloric acid has afforded a new fluoride cluster anion [Nb₆F₆ ⁱ Br₆ ⁱ Cl₄ ^a (H₂O)₂ ^a ]²⁻ isolated as the salt (Me₄N)₂[Nb₆F₆Br₆Cl₄(H₂O)₂]·6H₂O (space group R3m, a = 11.230(5) ?, c = 26.230(5) ?, V = 2865(2) ?³, Z = 3, R1 = 0.0362, R2w = 0.0886). The anion contains the cluster core Nb₆F₆Br₆ having ordered “inner” ligands. Difference in the atomic radii of “inner” ligands causes a significant distortion of the metal cluster along the three-fold axis. Original Russian Text Copyright ? 2008 by N. G. Naumov, S. Cordier, C. Perrin, and S. B. Artemkina __________ Translated from Zhurnal Strukturnoi Khimii, Vol. 49, No. 6, pp. 1163–1166, November–December, 2008.     

Ratiometric fluorescence signalling of fluoride ions by an amidophthalimide derivative

Fluorescence behaviour of 4-benzoylamido-N-methylphthalimide (1), designed and developed for selective detection of fluoride ions, is reported. 1 displays F⁻-induced colour change that allows its detection with the naked eye. The F⁻ specificity of the sensor system is evident from the fact that unlike F⁻, other halides do not affect the absorption characteristics of 1. Apart from the colorimetric response, the fluorescence output of 1 is also modulated by F⁻ in a manner that permits ratiometric fluorescence signalling of F⁻ as well. It is found that the system can detect F⁻ in the concentration range of 10–60 μM. The results of the experiments and theoretical calculations unambiguously suggest that the changes of the electronic absorption and fluorescence behaviour of 1, which have been exploited for signalling purpose, are due to F⁻-induced deprotonation of the 4-amido moiety of the sensor system.     

Effect of the Counter Anion and Solvate on the Structure,Stability and Spectral Properties of a Ruthenium(II) Complex Containing Group 15 Donors and 2,2′ :6′,2′′-terpyridine

Ruthenium complexes [Ru(κ³−tpy)(AsPh₃)₂C1]PF₆ · 0.42H₂O (tpy =2,2′:6′,2′′-terpyridine) (1) and a new crystal form of [Ru(κ³−tpy)(AsPh₃)₂Cl]BF₄ (2), which crystallized without water solvate, and their comparative studies on spectral, structure and stability aspects are reported. The complexes have been characterized by elemental analyses, FAB-MS, i.r., ¹H n.m.r. and electronic spectral studies. In these complexes weak C—H···Fπ and face-to-face π–π interactions lead to a single helical motif while, C—H···FX (X=F, Cl) interactions result in linear chains. Various studies on the stability of the complexes suggested that the compound containing the counter anion PF₆^- is more stable than the other containing BF₄^- as the counterpart.