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The Journal of Organic Chemistry Jul 2009A macrobicycle formed by a tetraoxadiaza macrocycle containing a dibenzofuran (DBF) spacer and an isophthalamide head unit, named DBF-bz, was used as receptor for anion...
A macrobicycle formed by a tetraoxadiaza macrocycle containing a dibenzofuran (DBF) spacer and an isophthalamide head unit, named DBF-bz, was used as receptor for anion recognition. The molecular structure of DBF-bz was established in solution by NMR and ESI-MS spectroscopies and in single crystal by X-ray diffraction analysis. The X-ray structure showed a water molecule encapsulated into the macrobicyclic cavity by four hydrogen bonds, two of them involving the two N-H amide binding sites and the oxygen of the water molecule (N-H...O hydrogen bonds) and the other two (O-H...N) involving the amine groups as hydrogen bonding acceptors. (1)H NMR temperature dependence studies demonstrated that the same structure exists in solution. The ability of this ditopic receptor to recognize alkali halide salts was evaluated by extraction studies followed by (1)H NMR and ESI-MS spectroscopies. The macrobicycle showed a capacity to extract halide salts from aqueous solutions into organic phases. The binding ability of this macrobicycle for halides was also quantitatively investigated using (1)H NMR titrations in CDCl(3) (and DMSO-d(6)) solution, and in acidic D(2)O solution. The largest binding association constant was found for the chloride anion and the completely protonated receptor. The results suggest that the diammonium-diamide unit of the receptor strongly bind the anionic substrate via multiple N-H...Cl(-) hydrogen bonds and electrostatic interactions. The binding trend follows the order Cl(-) > Br(-) > I(-) approximately F(-) established from the best fit between the size of the anion and the cavity size of the protonated macrobicycle. Molecular dynamics (MD) simulations of the DBF-bz in CHCl(3) solution allowed a detailed insight into the structural and binding properties of the receptor.
Topics: Anions; Benzofurans; Crown Ethers; Crystallography, X-Ray; Hydrogen Bonding; Macrocyclic Compounds; Molecular Structure
PubMed: 19449844
DOI: 10.1021/jo9005798 -
Inorganic Chemistry Nov 2011Tris(2-aminoethyl)amine (tren) based pentafluorophenyl-substituted tripodal L, tris[[(2,3,4,5,6-pentafluorobenzyl)amino]ethyl]amine receptor is synthesized in good yield...
Tris(2-aminoethyl)amine (tren) based pentafluorophenyl-substituted tripodal L, tris[[(2,3,4,5,6-pentafluorobenzyl)amino]ethyl]amine receptor is synthesized in good yield and characterized by single crystal X-ray diffraction analysis. Detailed structural aspects of binding of different anionic guests toward L in its triprotonated form are examined thoroughly. Crystallographic results show binding of fluoride in the C(3v)-symmetric cavity of [H(3)L](3+) where spherical anion fluoride is in tricoordinated geometry via (N-H)(+)···F interaction in the complex [H(3)L(F)]·[F](2)·2H(2)O, (3). In the case of complexes [H(3)L(OTs)]·[OTs](2), (4) and [H(3)L(OTs)]·[NO(3)]·[OTs], (5), tetrahedral p-toluenesulphonate ion is engulfed in the cavity of [H(3)L](3+) via (N-H)(+)···O interactions. Interestingly, complex [(H(3)L)(2)(SiF(6))]·[BF(4)](4)·CH(3)OH·H(2)O, (6) shows encapsulation of octahedral hexafluorosilicate in the dimeric capsular assembly of two [H(3)L](3+) units, via a number of (N-H)(+)···F interactions. The kinetic parameters of L upon binding with different anions are evaluated using a potentiometric study in solution state. The potentiometric titration experiments in a polar protic methanol/water (1:1 v/v) binary solvent system show high affinity of the receptor toward more basic fluoride and acetate anions, with a lesser affinity for other inorganic anions (e.g., chloride, bromide, nitrate, sulfate, dihydrogenphosphate, and p-toluenesulphonate).
Topics: Amines; Anions; Crystallography, X-Ray; Environmental Monitoring; Ethylenediamines; Fluorides; Ligands; Models, Molecular; Molecular Conformation; Potentiometry; Protons; Silicic Acid; Solutions
PubMed: 21942271
DOI: 10.1021/ic2011502 -
Clinica Chimica Acta; International... Jan 2015The majority of studies examining anionic composition in human saliva have focused on inorganic anions only, and accompanying organic anion concentration has often been...
BACKGROUND
The majority of studies examining anionic composition in human saliva have focused on inorganic anions only, and accompanying organic anion concentration has often been overlooked in the development of artificial salivas. The purpose of this study was to examine the major organic anionic species profile of human saliva, with a view to gaining further insight into human salivary chemistry.
METHODS
Unstimulated whole saliva was collected from 11 healthy volunteers over a period of 18months. Samples were subjected to ion chromatography for detection and quantification of organic and inorganic anions.
RESULTS
Among organic anions, acetate was predominant (0.24±0.38mmol/l), with lactate (0.01±0.04mmol/l), propionate (0.03±0.07mmol/l), and formate (0.02±0.03mmol/l) detected at lower levels. Acetate, propionate, and formate were detected in at least 80% of the saliva samples. Positive partial correlations were found between phosphate and sulfate (r=0.510, p-value=1.545×10(-4)), and between propionate and acetate (r=0.836, p-value=7.510×10(-14)).
CONCLUSION
Organic anionic species were consistently detected at low levels in saliva samples collected longitudinally over a period of 18months. These salivary components must be considered in order to understand saliva chemistry, and should not be neglected during the continuing development of artificial salivas.
Topics: Acetates; Anions; Chromatography, Ion Exchange; Female; Formates; Humans; Lactic Acid; Male; Phosphates; Propionates; Saliva; Sulfates; Young Adult
PubMed: 25181611
DOI: 10.1016/j.cca.2014.08.027 -
Organic Letters Sep 2013Anion receptors containing glucuronic acid were synthesized, and their anion binding ability studied. Chirality of anionic guests derived from mandelic acid and amino...
Anion receptors containing glucuronic acid were synthesized, and their anion binding ability studied. Chirality of anionic guests derived from mandelic acid and amino acids can be distinguished not only in terms of stability constants but also by significant differences in chemical shift changes for sugar moiety protons.
Topics: Amino Acids; Anions; Carboxylic Acids; Glucuronic Acid; Indoles; Magnetic Resonance Spectroscopy; Mandelic Acids; Models, Molecular; Molecular Structure; Protons; Stereoisomerism
PubMed: 23988260
DOI: 10.1021/ol402074u -
Molecules (Basel, Switzerland) Feb 2023The reaction of pyridine with cyanuric chloride was studied under microwave activation as well as in the presence of silver nitrate. The product of hydrolysis containing...
The reaction of pyridine with cyanuric chloride was studied under microwave activation as well as in the presence of silver nitrate. The product of hydrolysis containing two pyridinium rings and chloride anion was isolated. The structures of these anion exchanger salts with chloride, nitrate and perrhenate anions are discussed.
Topics: Nitrates; Chlorides; Salts; Anions; Triazines
PubMed: 36838929
DOI: 10.3390/molecules28041941 -
Journal of Chromatography. A Jul 1999Complex formation between borate compounds and vicinal diols is well recognized. Generally, in a chemically bonded anion-exchange resin, many hydroxyl groups are...
Complex formation between borate compounds and vicinal diols is well recognized. Generally, in a chemically bonded anion-exchange resin, many hydroxyl groups are introduced on the surface of the resin in order to make the resin hydrophilic. The borate as an eluting reagent also reacts to these hydroxyl groups, and this complex formation decreases the apparent ion-exchange capacity of the column by being dissociated to the anion depending on the eluent pH. In the present work a method is described for the simultaneous determination of anions based on the capacity gradient for suppressed ion chromatography. A Tosoh IC-Anion-PW column and dihydroxyphenylborane-mannitol eluent system were used. To maintain baseline stability, it was helpful to keep the borate concentration constant during a gradient of 16 to 0 mM mannitol as a modifier to prevent the complex formation with the hydroxyl on the resin. The chemical composition of the eluents and gradient profiles are discussed and the application to the analysis of the condensed phosphates with widely varying retention times as food additives in a cheese sample is presented.
Topics: Anions; Borates; Chromatography, Ion Exchange; Phosphates
PubMed: 10457467
DOI: 10.1016/s0021-9673(99)00493-8 -
The Journal of General Physiology Mar 1992Single channel currents though apical membrane Cl channels of the secretory epithelial cell line T84 were measured to determine the anionic selectivity and concentration...
Single channel currents though apical membrane Cl channels of the secretory epithelial cell line T84 were measured to determine the anionic selectivity and concentration dependence of permeation. The current-voltage relation was rectified with single channel conductance increasing at positive potentials. At 0 mV the single channel conductance was 41 +/- 2 pS. Permeability, determined from reversal potentials, was optimal for anions with diameters between 0.4 and 0.5 nm. Anions of larger diameter had low permeability, consistent with a minimum pore diameter of 0.55 nm. Permeability for anions of similar size was largest for those ions with a more symmetrical charge distribution. Both HCO3 and H2PO4 had lower permeability than the similar-sized symmetrical anions, NO3 and ClO4. The permeability sequence was SCN greater than I approximately NO3 approximately ClO4 greater than Br greater than Cl greater than PF6 greater than HCO3 approximately F much greater than H2PO4. Highly permeant anions had lower relative single channel conductance, consistent with longer times of residence in the channel for these ions. The conductance sequence for anion efflux was NO3 greater than SCN approximately ClO4 greater than Cl approximately I approximately Br greater than PF6 greater than F approximately HCO3 much greater than H2PO4. At high internal concentrations, anions with low permeability and conductance reduced Cl influx consistent with block of the pore. The dependence of current on Cl concentration indicated that Cl can also occupy the channel long enough to limit current flow. Interaction of Cl and SCN within the conduction pathway is supported by the presence of a minimum in the conductance vs. mole fraction relation. These results indicate that this 40-pS Cl channel behaves as a multi-ion pathway in which other permeant anions could alter Cl flow across the apical membrane.
Topics: Animals; Anions; Bicarbonates; Bromides; Cell Membrane Permeability; Chlorides; Dose-Response Relationship, Drug; Electric Conductivity; Epithelial Cells; Epithelium; Fluorides; Humans; Hydrogen-Ion Concentration; Iodine; Ion Channels; Nitrites; Phosphates; Temperature
PubMed: 1375274
DOI: 10.1085/jgp.99.3.339 -
Yakugaku Zasshi : Journal of the... 2016Monocarba-closo-dodecaborate (1; [closo-CB11H12](-), or C1-carborane anion) is a symmetrical, stable anionic cluster, which possesses low nucleophilicity/basicity and... (Review)
Review
Monocarba-closo-dodecaborate (1; [closo-CB11H12](-), or C1-carborane anion) is a symmetrical, stable anionic cluster, which possesses low nucleophilicity/basicity and exhibits three-dimensional aromaticity. In contrast to the rich applications of C2-carborane molecules (C2B10H12), the chemistry of the C1-carborane anion as a platform for functional molecules has not been thoroughly studied thus far due to the lack of its efficient functionalization. In particular, no efficient general methods are available for the introduction of aryl and sp(2)/sp-carbon groups at the carbon vertex of the C1-carborane anion. The unique electronic structure and potential applications of the C1-carborane anion prompted us to investigate methods to functionalize it. We developed a general, efficient C-C cross-coupling reaction of 1 under palladium catalysis which yields a variety of 1-C-functionalized C1-carborane derivatives. The use of copper(I) or lithium species as a transmetalating partner facilitated the cross-coupling process of the sterically hindered C1-carborane anion. The potential application of 1-C-arylated C1-carborane anion derivatives thus obtained were explored, some of which showed potential as pharmacophores and ionic liquid crystal behavior. Furthermore, conjugation between σ- and π-aromatic moieties in 1-C-arylated monocarba-closo-dodecaborate anion derivatives was identified by means of kinetic experimental studies combined with theoretical calculations.
Topics: Anions; Boron Compounds; Carbon; Copper; Organic Chemistry Phenomena
PubMed: 27252066
DOI: 10.1248/yakushi.15-00294 -
Chemistry (Weinheim An Der Bergstrasse,... Mar 2017Selective tuning of arylethynyl urea scaffolds for anionic guests requires an understanding of preferred binding motifs of the host-guest interaction. To investigate the...
Selective tuning of arylethynyl urea scaffolds for anionic guests requires an understanding of preferred binding motifs of the host-guest interaction. To investigate the binding preference of receptors without a pre-organized binding pocket, two electron-deficient phenylacetylene receptors with a single urea moiety have been prepared and were found to bind halides as 2:1 host-guest complexes that feature key CH-anion or anion-π interactions. These supporting interactions also appear to influence the mechanism of the 2:1 binding event.
Topics: Alkynes; Anions; Electrons; Hydrogen Bonding; Magnetic Resonance Spectroscopy; Models, Molecular; Molecular Structure; Urea
PubMed: 28198117
DOI: 10.1002/chem.201605452 -
The Journal of Physiology Aug 19961. Anionic current was studied by a whole-cell variation of the patch-clamp technique in blastoderm cells dissociated from medaka (Oryzias latipes) embryos at the early...
1. Anionic current was studied by a whole-cell variation of the patch-clamp technique in blastoderm cells dissociated from medaka (Oryzias latipes) embryos at the early blastula stage. The blastoderm cells were mechanically dissociated without using proteolytic enzymes. 2. The anionic current was deactivated by hyperpolarizing steps. The steady-state current-voltage (I-V) relationship of the anion current was accurately represented by the Boltzmann relation with z = 1.01 +/- 0.02 (+/- S.E.M., n = 4) for voltage-dependent activation when internal calcium ions were buffered at 100 nM by BAPTA-Ca2+ buffer. 3. When the internal calcium concentration was reduced to 10 nM, this anionic current became an external-calcium-dependent current and was remarkably decreased by removal of external calcium ions. Furthermore, this anionic current was almost abolished when the internal calcium concentration was greatly reduced by chelating Ca2+ ions with 10 mM BAPTA. 4. This current was not affected by replacing external Na+ with TEA+ or N-methyl-D-glucamine. The reversal potentials shifted by +58.6 mV for a 10-fold decrease in the external Cl-concentration. External Cl-ions were substituted with various anions and respective current-reversal potentials were measured. The order of permeability was I- > Br- > Cl- > F-. Both the outward and inward currents almost disappeared in external Cl(-)-free solutions. 5. The voltage dependency of the anionic current shifted in a positive direction with the reduction in the external Cl- concentration, the potentials at which half the channels were activated (V 1/2) being -59.8 +/- 1.2 mV (n = 4), -40.7 +/- 0.8 mV (n = 4), -14.9 +/- 0.7 mV (n = 4), and -0.7 +/- 0.6 mV (n = 4) for 135, 90, 67, and 45 mM Cl-, respectively. This implies that the inward current, brought by efflux of internal anions, decreases with reductions in the external Cl- concentration. In the presence of external 135 mM Br-, the voltage dependency of the anionic current shifted in the negative direction (V 1/2 = -84.5 +/- 1.0 mV and z = 0.91 +/- 0.02 (n = 3)) in comparison with that in the external Cl- medium. It further shifted in the negative direction in the presence of 135 mM I- (V 1/2 = -93.8 +/- 1.5 mV and z = 0.85 +/- 0.03 (n = 3)). The inward current of the anion channel is considered to be affected by both the type and the concentration of external halide ions. 6. At the beginning of the blastula stage, the blastocoel cavity is formed for the first time. A mechanism is necessary to transport ions to the cavity without losing them to pond water outside the embryos. Since this anion channel is external-anion dependent, the current cannot be activated in the membrane facing the pond water, where concentrations of anions are much lower than those of the intracavernous solution. Only after blastocoel formation are blastoderm cells first exposed to the extracellular fluid with high ionic concentrations. Then, the anion channel would become effective for maintaining the Cl- equilibrium potential.
Topics: Animals; Anions; Blastoderm; Chlorides; Embryo, Nonmammalian; Female; Ion Channels; Male; Oryzias; Patch-Clamp Techniques
PubMed: 8866351
DOI: 10.1113/jphysiol.1996.sp021573