Maleate Ions Research Articles

Crystal growth and physical characterization of bismaleato lead (IV) grown in silica gel

Single crystals of bismaleato lead(IV) [Pb2(C4H2O4)2] are grown by the controlled diffusion of lead ions in gelated hydrosilica matrix impregnated with maleate ions. The various functional groups present in the compound is identified using FTIR spectrum. The structure of the crystal was elucidated using single crystal XRD studies. It crystallizes in the monoclinic system with space group P21/c. The TG- DTA analysis was employed l to explore the thermal stability and decomposition the pattern. the dielectric measurements were made over wide frequency and temperature ranges. The optical band gap was determined using diffuse reflectance spectroscopy.

Maleate ions as ligands in crystal structures of coordination compounds, including two uranyl complexes

Synthetic techniques, FTIR spectra and the crystal structures of two new uranyl complexes with maleate ions are reported. The crystal structure of (NH4)2[UO2(C4H2O4)2] (I) is constructed of chains with the [UO2(C4H2O4)2]2− composition. Maleate ions in I have the tridentate bridging and chelating T11-4 coordination mode with the formation of 4-membered U-containing rings. The crystal structure of Cs2[(UO2)3(C4H2O4)4]·2H2O (II) is constructed of layers with the [(UO2)3(C4H2O4)4]2− composition. Half of the maleate ions in II have the bridging and chelating Q21-4 coordination mode, with the formation of 4-membered rings, while the other half have the Q21-7 coordination mode with the formation of 7-membered rings. The coordination modes of the maleate ions in all the crystal structures of coordination compounds from the CSD were analyzed. The non-planarity of the maleate ions is confirmed by calculation of different geometric parameters. Though in all crystal structures most of the maleate ions tend to realize coordination modes with the formation of 7-membered rings, geometrical difficulties of 7-membered ring formation are shown. The presented data on the coordination modes of the maleate ions in crystal structures are of particular interest for crystal engineering and crystal structure prediction.

L’Oreal sued over hair protection knockoff

Celebrities Taylor Swift and Jennifer Lawrence went blonde using it, and now L’Oreal is charged with stealing it: the formula for Olaplex’s Bond Multiplier, a product that protects hair during bleaching and color treatments. The bad blood emerged late last year in a suit filed in federal court for the Central District of California. In it, start-up firm Olaplex charged L’Oreal with violating a patent covering hair protection ingredients discovered by a University of California, Santa Barbara (UCSB), chemist and a former student. Olaplex is seeking an injunction against L’Oreal and unspecified damages. In response, L’Oreal says “we strongly oppose the merit of these claims and the validity of the patent, and L’Oreal will defend this position vigorously.” The original active ingredient the two scientists discovered was bis-aminopropyl diglycol dimaleate, a molecule with maleate ions on either end. According to Olaplex, it works by keeping bleaching and coloring agents from

On the Mechanism of Reduction of Maleate Ions by Ni I Complexes with Tetraazamacrocyclic Ligands in Aqueous Solutions

Recently, it was shown that NiI and CoI complexes with tetraazamacrocyclic ligands [namely, trans-III-NiIL3+ (L3 = 1,4,8,11-tetraazacyclotetradecane), NiIcyclam and rac-CoIL1+ (L1 = 5,7,7,12,14,14-hexamethyl-1,4,8,11-tetraazacyclotetradeca-4,11-diene, dien)] reduce maleate ions in aqueous solutions. It was decided to expand the study to further NiILi+ complexes. In the present study, the reactions of rac-NiIL1+ and meso-NiIL2+ (L2 = 5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane) with maleate ions were investigated. The effect of the addition of maleic acid to aqueous solutions containing these low-valent metal complexes, prepared by the pulse radiolysis technique, was studied. The d→π* complexes formed between monovalent nickel complexes and maleate ions were detected and characterised by UV/Vis spectroscopy. The nature of the final products formed depends strongly on the nature of the metal and the ligand. Detailed mechanisms of the reduction processes are proposed and compared with those previously reported. The results indicate that the electronic configuration of the central cation as well as the reduction potential of the complex and steric hindrance induced by the ligand affect the reduction mechanism of maleate ions by these analogous complexes.

A new colorimetric receptor for selective detection of maleate vs. fumarate and ratiometric detection of F− ions

Two new receptors, R1 and R2, were designed and synthesized for the isomeric discrimination of maleate ions over fumarate ions. Receptor R1 showed high selectivity with a significant color change from colorless to orange red with Δλmax of 104 nm. This was owing to the hydrogen bonded electrostatic interactions of maleate ions with receptor R1. The formation of hydrogen bond between receptor R1 and maleate ions was confirmed by 1H NMR titrations, where the signal at δ 12.25 corresponding to the benzohydrazide –NH proton showed a downfield shift upon binding with the anion. Receptor R3 did not show any binding with maleate ions or fumarate ions due to steric hindrance. Receptors R1 and R2 detected F− ions with color changes from colorless to orange and colorless to pale yellow, respectively. Upon incremental addition of F− ions, the color was further transformed from orange to blood red in receptor R1 and pale yellow to dark yellow in receptor R2. This result was due to the formation of initial hydrogen bonds followed by the deprotonation of receptors at higher concentrations of F− ions.

Poly[tetraaquabis(μ-hydrogen maleato)barium(II)

In the title compound, [Ba(C4H3O4)2(H2O)4]n, the barium(II) cation is coordinated by five O atoms from four different hydrogen maleate ions and four O atoms from water mol­ecules in a tricapped trigonal prismatic geometry. The coordination polyhedra are connected by edge-sharing to form zigzag chains, which are linked by hydrogen bonds into an extended three-dimensional network.

Bis(2-aminopyridinium) maleate.

Two cyclic eight-membered hydrogen-bonded rings exist in the title compound, 2C(5)H(7)N(2)(+) x C(4)H(2)O(4)(2-), involving the 2-aminopyridinium and maleate ions. The dihedral angle between the two pyridinium rings hydrogen bonded to the maleate ion is 74.80 (4) degrees. The maleate anion lies on a twofold axis and is linked to the pyridinium cations by intermolecular N-H.O hydrogen bonds. The heterocycle is fully protonated, which enables amino-imino tautomerization.

Application of the Bifunctional Switch-Type Cryptand Ion Chromatographic Stationary Phase for Ion Separation

ABSTRACT Poly(styrene/divinylbenzene) resin with cryptand 22 as an anchoring group was synthesized and applied in ion chromatography as a packing material for separations of organic anions as well as cations. The cryptand can not only form strong complexes with metal cations, but it has also shown a remarkable complexing ability with organic anions after protonation at pH < 7. The protonated cryptand resin has been applied as an anion exchanger to successfully separate some organic carboxylate anions including HCOO−, CH3COO−, CH3CH2COO−, and some geometric isomers, e.g., fumarate and maleate ions, with water as the eluent. Alternatively, after deprotonated at pH > 7, the cryptand resin can be switched as a cation exchanger to separate inorganic cations. The effects of solvents, temperature, pH values, and flow rates of eluents on the separation of organic anions were also investigated.

The crystal structure of trypanothione reductase from the human pathogen Trypanosoma cruzi at 2.3 A resolution.

Trypanothione reductase (TR) is an NADPH-dependent flavoprotein unique to protozoan parasites from the genera Trypanosoma and Leishmania and is an important target for the design of improved trypanocidal drugs. We present details of the structure of TR from the human pathogen Trypanosoma cruzi, the agent responsible for Chagas' disease or South American trypanosomiasis. The structure has been solved by molecular replacement, using as the starting model the structure of the enzyme from the nonpathogenic Crithidia fasciculata, and refined to an R-factor of 18.9% for 53,868 reflections with F > or = sigma F between 8.0 and 2.3 A resolution. The model comprises two subunits (968 residues), two FAD prosthetic groups, two maleate ions, and 419 water molecules. The accuracy and geometry of the enzyme model is improved with respect to the C. fasciculata enzyme model. The new structure is described and specific features of the enzyme involved in substrate interactions are compared with previous models of TR and related glutathione reductases from human and Escherichia coli. Structural differences at the edge of the active sites suggest an explanation for the differing specificities toward glutathionylspermidine disulfide.

Crystal Structure at 110 K of (R)-1-Phenylethylammonium Hydrogen Maleate--Water (1/0.25), and a Study of the Conformation of 1-Phenylethylammonium Ions.

The title compound crystallizes in the orthorhombic space group C2 with a=39.191, b=5.624, c=11.247A, and β=95.750°, Z=8,. Using 3182 reflections the structure was refined to R=0.027 and R w =0.032. A short asymmetric intramolecular hydrogen bond is observed in both crystallographically independent anions; the two O-O distances are 2.42 and 2.44A. One of the hydrogen maleate ions displays a significant twist of the carboxylic groups relative to the double bond. The two (R)-1-phenylethylammonium ions are virtually identical. The water molecule links one of the cations to one of the anions

Effect of selected impurities on the continuous precipitation of calcium sulphate (gypsum)

AbstractThe effects of selected cationic and anionic impurities on the precipitation of gypsum in aqueous brine have been studied in a continuous MSMPR crystalliser. Crystal size distributions, determined by in situ Malvern laser light‐scattering measurements, were found to be bimodal. The suspected presence of agglomerates was confirmed by microscopy. Aluminium and maleate ions both enhanced the degree of agglomeration, but reduced the overall growth and nucleation rates. Contrary to expectation, fumarate ions also exerted an observable effect on both agglomeration and crystal growth.

ChemInform Abstract: KINETICS AND MECHANISM OF OSMIUM TETROXIDE CATALYSED OXIDATION OF MALEATE AND FUMARATE IONS WITH ALKALINE FERRICYANIDE

Chemischer InformationsdienstVolume 6, Issue 22 Preparative Organic Chemistry ChemInform Abstract: KINETICS AND MECHANISM OF OSMIUM TETROXIDE CATALYSED OXIDATION OF MALEATE AND FUMARATE IONS WITH ALKALINE FERRICYANIDE M. P. SINGH, M. P. SINGHSearch for more papers by this authorH. S. SINGH, H. S. SINGHSearch for more papers by this authorB. S. ARYA, B. S. ARYASearch for more papers by this authorA. K. SINGH, A. K. SINGHSearch for more papers by this authorA. K. SISODIA, A. K. SISODIASearch for more papers by this author M. P. SINGH, M. P. SINGHSearch for more papers by this authorH. S. SINGH, H. S. SINGHSearch for more papers by this authorB. S. ARYA, B. S. ARYASearch for more papers by this authorA. K. SINGH, A. K. SINGHSearch for more papers by this authorA. K. SISODIA, A. K. SISODIASearch for more papers by this author First published: June 3, 1975 https://doi.org/10.1002/chin.197522201AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume6, Issue22June 3, 1975 RelatedInformation

The Complex Formation between Pb2+ Ion and the Maleate and Hydrogen Maleate Ions.

The Complex Formation between Pb2+ Ion and the Maleate and Hydrogen Maleate Ions.

Adsorption of maleate and fumarate ions at the mercury — water interface

Adsorption of maleate and fumarate ions at the mercury — water interface

Adsorption of maleate and fumarate ions at the mercury-water interface

Adsorption of maleate and fumarate ions at the mercury-water interface

Molecular orbital studies of the hydrogen bond

Extended Hückel and CNDO/2 molecular orbital methods have been employed to examine a variety of intermolecular and intramolecular hydrogen bonds including the symmetric bonds in the bifluoride and maleate ions. These molecular orbital methods provide valuable information on the dissociation energies, charge densities, bond orders, and dipole moments. The CNDO/2 method gives realistic double minimum potentials for the proton in the asymmetric hydrogen bonds and a single minimum potential in the bifluoride and maleate ions.

Thyroxine binding proteins of human serum at physiological pH.

ABSTRACT The binding characteristics of human TBG, TBPA and TBA of T4 and T3 were studied by agar gel electrophoresis in a variety of buffers. The highest maximal binding capacities of TBG and TBPA were found in Hank's balanced salt solution at pH 7.4. Phosphate and tris maleate ions at this pH resulted in the reduction of the thyroxine maximal binding capacity of TBG and TBPA. It was also shown that pH, ionic constitution and molarity of the system affect the distribution of tracer T4125I among the specific protein carriers. Thyroxine binding inhibitors were shown to affect TBPA, TBA and TBG at a physiological pH like the effect described at other pH levels. The relative binding potency of TBPA for thyroxine:DNP:salicylate:penicillin was in a ratio of 670:250:10:1, respectively. An attempt to deal with the binding capacity data by the Scatchard technique is described.

Glutaminase isozymes in rat kidney

In 1958 Sayer and Roberts reported on the mode of activation of glutaminase by phosphate using a dog kidney preparation. More recently Kvamme et al. (1965) showed that the activation by phosphate involves a conformational change of the enzyme protein of pig kidney. The authors found that there are two types of glutaminase in rat kidney. The two are completely different in their properties and only one has been reported previously. This discovery of the second isozyme may be due to our use of rat kidney which contains much of the new enzyme, while dog or pig kidney contain only a little. The present paper gives a comparison of the properties of the two glutaminase isozymes. One isozyme requires phosphate for activity (phosphate dependent) while the other does not require phosphate either as a co-factor or activator (phosphate independent), but is activated by carbonate and maleate ions. Differences in the properties of the two glutaminase isozymes are reported and their metabolic roles in relation to ammonium excretion in the kidney are discussed briefly.