Novel chiral fluorescent macrocyclic receptors: synthesis and recognition for amino acid anions

New chiral fluorescence macrocycles 1 and 2 containing naphthalene and amino acid units were synthesized. The binding properties for amino acid anions were examined by the fluorescence and ¹H NMR spectra. The results indicated good enantioselectivity of 1 toward the N-protected phenylalanine anions.     

Exchange kinetics of amino acid anions in solutions of ternary copper(II) complexes with diethylenetriamine

Rate constants for the chemical exchange of some amino acid anions in solutions of copper(II) ternary complexes with diethylenetriamine have been determined by the NMR method. The coordination of amino acid anions in ternary and binary species is different and ligand substitution in the Cu(II) complexes follows an associative mechanism.

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The aromatic amino acid behaviour in aqueous amide solutions

The enthalpies of solution of L-phenylalanine in the mixtures of water with the protein denaturant urea have been measured in the temperature range of 288.15–318.15 K. Using the results of the present research and literature data of free energies, the standard thermodynamic functions of the solute transfer from water to aqueous urea solutions have been estimated in a wide temperature range. The enthalpic, heat capacity, entropic and free energy parameters of the solute-urea pair and triplet interactions have been computed. The amino acid — amide pair interaction was found to be attractive in the temperature range studied due to the favourable enthalpic term. The triplet interaction being slightly repulsive reveals the enthalpic origin also. The examination of the Savage and Wood additivity-of-groups approach does indicate the inapplicability of this scheme to enthalpies and entropies of interaction. It has been found for the first time that the heat capacity of interaction changes its sign at 303 K, i.e. the temperature dependence of enthalpic and entropic parameters passes through the pronounced extrema near the temperature of the minimum of the heat capacity of pure water.     

Behavior of metal complexes of polyacrylic acid in solutions

Metal complexes of polyacrylic acid containing Li, Li, and Cu, or Li and Zn have been studied in saline aqueous solutions using molecular hydrodynamics and light scattering methods. Intrinsic viscosities, weight-average molar masses, hydrodynamic radii, and radii of gyration were obtained. It was shown that the macromolecules of polymetalloacrylates containing divalent metals form small and large supramolecular structures, their dimensions, and composition being dependent on the ionic strength of the solution.     

Self-assembly properties of some chiral N-palmitoyl amino acid surfactants in aqueous solution

Various chiral N-palmitoyl amino acid surfactants (AAS) derived from methionine, proline, leucine, threonine, phenylalanine and phenylglycine were prepared and converted to their sodium salt. The properties of the aggregates formed in aqueous solution were studied for both the optically-active compounds and their racemic mixture. Characterization was made by surface tensiometry, fluorimetry, dynamic light scattering, circular dichroism (CD) and transmission electron microscopy. It appeared that most of the AAS studied in this work spontaneously formed different types of aggregates, including micrometer-sized aggregates. No significant difference could be found between the critical aggregation concentration (cac) value of pure enantiomers and that of the racemic forms. CD spectra did not reveal any aggregation-induced chirality.     

Structural study of bismuth complexes with diethylenetriaminepentaacetic acid in aqueous solutions

Bismuth complexes with diethylenetriaminepentaacetic acid were examined in aqueous solutions (pH 4–10) by UV, IR, and NMR spectroscopy. In aqueous solutions, the polydentate ligand is coordinated to bismuth through three N atoms and five O atoms.     

An enantioselective fluorescence sensing assay for quantitative analysis of chiral carboxylic acids and amino acid derivatives

A chiral 1,8-diacridylnaphthalene-derived fluorosensor exhibiting a C(2)-symmetric cleft designed for stereoselective interactions with hydrogen bond donors has been used for the determination of both concentration and enantiomeric composition of carboxylic acids and amino acid derivatives.     

Gel permeation chromatography of simple anions in aqueous solutions

Semi-automatic liquid chromatographic apparatus is described for the separation of simple inorganic anions in aqueous solution, using dextran gels for the separation and differential conductivity for detection. The influence of different types of eluent on the degree and order of separation is discussed.     

含氨基酸Schiff碱-金属手性配合物的合成及其相关反应进展

本文综述了"含氨基酸Schiff碱-金属"手性配合物的合成及其结构。同时还讨论了"含氨基酸Schiff碱-金属"手性配合物不对称反应, 如: 烷基化反应、缩合反应、Michael加成反应、溴化反应等。这些反应为氨基酸拆分及非蛋白质类氨基酸合成提供了新方法。     

Spectroscopic studies of the metal complexes of ethylenediaminetetra-acetic acid in aqueous solution

Aqueous solutions of the metal complexes of ethylenediaminetetra-acetic acid (EDTA) are widely used in analysis; though X-ray diffraction methods cannot be directly used for structural determination in solution, ultraviolet-visible region, vibrational and NMR spectroscopy studies demonstrate that the species in solution adopt a similar range of stereochemistries to those determined for the solid state. Thus a review of the spectroscopic properties of the solutions suggests that chelates are formed in which the denticity of EDTA varies from one to six and the co-ordination number about the metal from four to nine.     

Fluorometric sensing of alkali metal and alkaline earth metal cations by novel photosensitive monoazacryptand derivatives in aqueous micellar solutions

Novel monoazacryptand-type fluorescent chemosensors, (derived from an 18-crown-6) and (derived from a 15-crown-5) both with a pyrene ring as their photoresponsive moiety, were synthesized. Their fluorescence properties for alkali metal and alkaline earth metal cations in water were then examined. The detection of metal cations was accomplished by a change in the fluorescence intensity of the host compounds, based on a photoinduced electron transfer (PET) mechanism. In aqueous solution, showed little fluorescence upon the addition of Ba2+ because of the very weak complexation with Ba2+, but the presence of micelles of polyoxyethylene(10) isooctylphenyl ether (Triton X-100) enabled to show highly sensitive and selective Ba2+ detection among alkali metal and alkaline earth metal cations. With respect to the selective fluorescent detection of important metal cations (Na+, K+, Mg2+, Ca2+) relevant to living organisms, was found to detect K+ with high selectivity in aqueous micellar solutions of polyoxyethylene(20) sorbitan monostearate (Tween-60). The selectivity for metal cations was mainly dependent on the goodness of fit of the host cavity and the metal cation size. In the presence of anionic surfactants, detected alkaline earth metal cations more effectively than alkali metal cations.     

Free energy relationships in aqueous amino acid and peptide solutions containing sodium chloride

Three systems of the type amino acid or peptide-sodium chloride-water have been investigated over wide solute molality ranges using the isopiestic vapor pressure method. The amino acid employed was L--alanine, while the peptides were diglycine and triglycine. Equations were obtained for the activity coefficients of these compounds in the salt solutions in terms of the molalities of the solutes. The trace activity coefficients of the peptides were negative at low salt molality and became positive as the salt molality was increased. The limiting interaction parameters were calculated for the systems using the Kirkwood ion-dipole expression and empirical quantities derived from previous work to obtain the salt effect on the nonpolar and amide portion of the molecule. Good agreement was obtained between the calculated values and the experimental results in the case of diglycine, but they diverged in the case of triglycine. The calculated value for L--alanine is in poorer agreement with the experimental value than for the other amino acids studied previously.Presented in part at the Second International Conference on Calorimetry and Thermodynamics, Orono, Maine, July 1971.     

Synthesis of methacrylate-functionalized phosphonates and phosphates with long alkyl-chain spacers and their self-aggregation in aqueous solutions

Abstract  Polymerizable amphiphilic organophosphorous compounds were synthesized and their self-aggregation behavior was investigated. The studied molecules contain a hydrophilic phosphorus end group, an alkyl chain spacer with a variable length from 3 to 11 CH₂ groups and a polymerizable methacrylic group at the other chain end. Thus, the molecules represent a class of polymerizable surfactants. Two different reaction methods were used; either unsaturated alcohols or bromine-containing alcohols were applied as starting compounds for the preparation of the organophosphorous surfactants. The self-aggregation and micelle formation of the prepared compounds were investigated in aqueous solution by dynamic light scattering measurements. The critical micelle concentration of the P-containing amphiphiles was in all cases smaller than 0.040 mol/l and strongly dependent on the polarity of the phorphorous head group and the chain length of the spacer. Graphical abstract   The synthesis of organophosphorous amphiphiles as surface active monomers for the modification of metal oxide surfaces is presented. The spacer between the phosphorous head group and the methacrylate group was varied with regard to their length and composition. The self-aggregation behavior of these methacrylate-functionalized phosphates and phosphonates surfactants was investigated.     

Heat capacities of aqueous solutions of amino acid and dipeptide derivatives of fullerene

The concentration dependences of heat capacities of aqueous solutions of several amino acid and peptide derivatives of fullerene were measured by scanning differential calorimetry at 298 K. The heat capacities for the arginine, alanylalanine, and glycylvaline derivatives dissolved in water depend slightly on concentration. The concentration dependences of the heat capacities of aqueous solutions of the serine and alanine derivatives display extrema. The calculated contributions of hydration to the heat capacities of the dissolved fullerene derivatives have both positive and negative signs. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2202–2204, November, 1998.     

Amino-substituted gem-diphosphonic acids: structures of complexes with divalent metal cations in aqueous solutions

A comparative study of complexation of acids R₂N(CH₂)_nCR"(PO₃H₂)₂ (R = H or Me; R" = OH or H; n = 1 or 2) with the Ca²⁺, Mg²⁺, Zn²⁺, and Cu²⁺ cations in aqueous solutions was carried out by vibrational (IR and Raman) and electronic spectroscopy using the data of ESR spectroscopy and conformational analysis (molecular mechanics). The MOPCPO chelate ring is formed in all ML and MHL complexes. The involvement of the N atom in coordination was found only in the Cu²⁺ complexes and is determined by the structure of the ligand. The relationship between the stability constants and the structures of the complexes in aqueous solutions is analyzed.     

Colorimetric "naked eye" sensing of anions in aqueous solution

[structure: see text] The synthesis and UV-vis and NMR spectroscopic studies of thiourea-based colorimetric sensors for anions are presented. These sensors can recognize anions through hydrogen binding even in competitive pH-buffered aqueous solutions, giving rise to large color changes that are clearly visible to the naked eye.     

水相法合成双(环戊二烯基)钛氨基酸配合物的研究

以N-(取代苯基)氨基乙酸及盐与双(环戊二烯基)二氯化钛在水相及有机相反应,得到了五个双(环戊二烯基)钛氨基酸配合物,对配合物进行了熔点、元素分析、IR及^1HNMR的表征,确定了它们的结构。这些配合物在空气中稳定。经比较,水相中的合成反应速度快,操作简便,产物较易分离,产率高。     

Density,viscosity, and N2O solubility of aqueous amino acid salt and amine amino acid salt solutions

Physicochemical properties of aqueous amino acid salt (AAS), potassium salt of sarcosine (KSAR) and aqueous amine amino acid salt (AAAS), 3-(methylamino)propylamine/sarcosine (SARMAPA) have been studied. Densities of KSAR were measured for sarcosine mole fraction 0.02 to 0.25 for temperature range 298.15 K to 353.15 K, the viscosities were measured for 0.02 to 0.10 mole fraction sarcosine (293.15 K to 343.15 K) while the N₂O solubilities were measured from 0.02 to 0.10 mole fraction sarcosine solutions (298.15 K to 363.15 K). Densities of SARMAPA were measured for sarcosine mole fraction 0.02 to 0.23 for temperature range (298.15 K to 353.15 K), viscosities were measured for 0.02 to 0.16 mole fraction sarcosine (293.15 K to 343.15 K) while the N₂O solubilities were measured from 0.02 to 0.16 mole fraction sarcosine solutions (298.15 K to 343.15 K). Experimental results were correlated well with empirical correlations and N₂O solubility results for KSAR were predicted adequately by a Schumpe model. The solubilities of N₂O in AAS and AAAS are significantly lower than values for amines. The solubilities vary as: amine > AAAS > AAS.