Structural studies on some inorganic ion exchangers

Ferrocyanides of zirconium(IV) and tin(IV), antimonates of cerium(IV) and titanium(IV), and cerium(IV) tungstate, has been shown to be useful materials as inorganic ion exchangers in radio- and analytical chemistry. These materials are sufficiently stable towards high dose of γ-radiations. Attempt is made to study some structural aspects and possible exchange sites of these materials using different techniques like thermal, Mössbauer and infrared spectroscopy.     

Adsorption of some hazardous radionuclides on cerium (IV) antimonate

Cerium(IV) antimonate was prepared by dropwise addition of 0.6M antimony pentachloride and 0.6M cerium ammonium nitrate solutions by a molar ratio of Ce/Sb 0.75. Exchange isotherms for H⁺/Co²⁺, H⁺/Cs⁺, H⁺/Zn²⁺, H⁺/Sr²⁺ and H⁺/Eu³⁺ were determined at 25, 40 and 60°C. Besides, it was proved that europium is physically adsorped, while zinc, strontium, cobalt and cesium are chemically adsorbed. Moreover, the heat of adsorption of zinc, strontium, cobalt and cesium on cerium (IV) antimonate was calculated and indicated that cerium(IV) antimonate is of endothermic behavior towards these ions. Also the distribution coefficients of these ions were determined and it was found that the selectivity is in the order: Eu³⁺>Sr²⁺>Cs⁺>Na⁺.     

Structural studies on some 1,3,5,7-tetraaza- and 1,3,5-triazaadamantane derivatives

¹H and ¹³C NMR data are reported for hexamethylenetetramine (hexamine), 7-nitro-1,3,5-triazaadamantane and some of their quaternary derivatives. INDO molecular orbital calculations have been performed on these molecules to aid the interpretation of their spectra.     

Structural studies on some N-nitramines and N-nitrosamines

INDO-MO calculations are reported for some N-nitramines and N-nitrosamines. Reasonable agreement is obtained between the calculated dipole moments of the lowest energy conformations and experimental data. The calculated energy barrier to rotation about the N-N bond in dimethyl nitrosamine and dimethyl nitramine is in good agreement with experiment. Some calculated spin-spin coupling constants for dimethyl nitramine are also reported.     

Structural studies on some 1,3,5,7-tetraazabicyclo-[3.3.1]-nonane derivatives

From a study of the ¹H NMR spectra of a number of 3,7-disubstituted derivatives of 1,3,5,7-tetraazabicycio - [3.3.1] - nonane it is concluded that these molecules exist in either chair-chair or flattened chair-chair conformations. The derivatives containing COCH₃ and NO substitutents have room temperature spectra consistent with restricted rotation about their NC and NN bonds respectively. High temperature spectra reveal an activation energy, for the rotational barrier of the NC bond in the diacetyl derivative, of 23±2K.Cal/mol.     

Rapid separation of some alkaloids of toxicological and pharmaceutical importance on zirconium antimonate paper

Summary Chromatographic behaviour of opium and strychnos alkaloids, along with atropine and ephedrine, on paper impregnated with zirconium antimonate using aqueous eluents is reported. Numerous separations of alkaloid mixtures containing up to five components were achieved within 15 minutes.     

Structural studies on some iron 8-oxi-quinolinates using Mössbauer spectroscopy

Using Mössbauer spectroscopy the quinolinates of iron/II/ and iron/III/ have been studied. In iron/II/ quinolinate three sublattices were evidenced, two of them being attributed to Fe²⁺ ions and the third to Fe³⁺ impurities. In the iron/III/ quinolinate five structural sublattices were found, two of them containing Fe³⁺ ions, the other two Fe²⁺ ions and the fifth may be attributed to the interstitial Fe³⁺ ions.     

若干含氧桥双核钼(V)原子簇化合物的研究

本文在测定了五个新颖双核钼(V)簇合物的晶体结构(QH)4[Mo2O4(NCS)6](1),H(PyH)3.[Mo2O4(C2O4)2(H2O)2]2.2H2O(2), (QH)3[Mo2O4(C4H3OCOO)(NCS)4](3),(QH)3[Mo2O4.(CH2OH)(NCS)5](4)和(PyH)4[Mo2O3(SO4)(NCS)6](5)以及文献报道该类型化合物结构数据的基础上, 综述了含氧桥双核钼(V)簇合物的结构特征, 并应用SCC-EHMO方法探讨了该类型化合物的电子结构和成簇机理, 最后用简征坐标分析法, 研究了含氧桥双核钼(V)化合物簇胳单元[Mo2O4]^2^+和[Mo2O3SO4]^2^+的振动结构及其红外谱带归属。     

Structural studies of columnar phases of some chiral disc-like molecules

We have performed a structural study of the mesophases of some isomeric hexa-substituted phenanthrenes. Evidence for a new hexagonal columnar mesophase with three columns per unit cell was found in a chiral isomer. Moreover, a rectangular columnar phase with four columns per lattice, similar to the low temperature mesophase of a hexa-substituted rufigallol, was found in a different material. The relations between the structures and the electro-optical behaviour of the different mesophases are discussed.     

Thermodynamics of ion-exchange on ferric antimonate

A simple approach to ion-exchange equilibria on ferric antimonate has been applied. The values of selectivity coefficients for Ba²⁺, Mg²⁺, Ca²⁺ and Sr²⁺ have been measured using equilibrium experiments at constant ionic strength and at different temperatures from 20 to 60°C. The thermodynamic equilibrium constant and values of ΔG°, ΔH° andΔS° are reported.     

Structural and spectroscopic studies on some chloropyrimidine derivatives by experimental and quantum chemical methods

Ab initio quantum chemical and experimental spectroscopic studies in the infrared (4000-60 cm(-1)) and UV spectral regions are being reported on 4-chloro-2,6-dimethylsulfanyl pyrimidine-5-carbonitrile and 4-chloro-2-methylsulfanyl-6-(2-thienyl) pyrimidine-5-carbonitrile. Optimized geometries, electronic charge distribution, dipole moments and three-dimensional molecular electrostatic potential surfaces have been obtained. These have been used to understand the structure and spectral characteristics of the two compounds. A complete assignment of vibrational spectra on the basis of DFT/6-311G** and electronic spectra on the basis of TD-DFT/6-31+G* 5D calculations have been attempted for the two molecules.     

Radiation stability of some thermally stable inorganic ion exchangers

The effect of -irradiation on the ion-exchange capacity, distribution coefficient and the efficiency for binary separations of some thermally stable inorganic ion exchangers have been studied. Irradiation upto 100 Mrad, has no effect on these substances, except thorium tungstate which showed changes in ion-exchange capacity, distribution behaviour and in binary separations.     

Radiation stability of some thermally stable inorganic ion exchangers

Effect of various doses of gamma radiation on the ion-exchange capacity, distribution coefficient values, elution behaviour, pH titration and infrared spectra of some thermally stable inorganic ion exchangers has been studied systematically. No change has been observed in the ion-exchange capacity, elution behaviour and the infrared spectra of the materials irradiated up to a total dose of 3·10⁸ rad, while, a change has been observed in their pH-titration and distribution behaviour.     

Structural characterization of some substituted azolidine molecules: UPS photoelectron spectroscopic studies

The He(I) photoelectron spectra of some heterocyclic penta-atomic rings containing carboamido, thiocarbamido or selenocarbamido groups are reported. Ab initio and CNDO/2 computational methods have been used to assign the first four ionized molecular orbitals, by comparison with previously studied related molecules. Structural effects in homologous series of compounds, particularly conjugation between N and the CY (Y = O, S, Se) moiety, and the through-space interaction between ring heteroatoms are analysed.     

Structural studies in main group chemistry : XXII. Structural and tin-119 mössbauer studies of some five-coordinate triorganotin anions

The structures of two complexes, [Ph₃PCH₂Ph]⁺[Bu₃SnCl₂⁻]⁻ and [Ph₃AsCH₂COPh]⁺[Ph₃SnCl₂]⁻, have been determined by X-ray diffraction. Both materials are monoclinic, space group P2_1/c. Unit cell data for [Ph₃PCH₂Ph]⁺−[Bu₃SnCl₂]⁻ are a 9.8521(6), b 16.9142(4), c 22.3517(7) Å, β 91.4235(9)°; and for [Ph₃AsCH₂COPh]⁺[Ph₃SnCl₂]⁻ a 34.9760(3), b 11.1290(5), c 24.2410(2) Å, β 108.56(2)°, and both consist of the component ionic species. The organotin anions each have trigonal bipyramidal geometry with equatorial organic groups and axial halogens. In the [Ph₃SnCl₂]⁻ anion the two Sn---Cl bond distances are the same (2.58(1) and 2.60(1) Å), but in [Bu₃SnCl₂]⁻, as in [Me₃SnCl₂]⁻, they are substantially different (2.573(7) and 2.689(6) Å). The Sn---C bond distances also vary: [Ph₃SnCl₂]⁻ 2.15(4), 2.16(3) and 2.25(5); [Bu₃SnCl₂]⁻ 2.21(1), 2.20(2) and 2.29(2) Å. Tin-119 Mössbauer data for these and several other similar complexes are also reported.     

Fr and Ra fixation on some inorganic sorbents or mixed composite ion exchangers

Zinc and nickel hexacyanoferrates (II) present a high affinity for²²³Fr and no retention for²²³Ra in hydrochloric acid solutions with concentrations greater than 0.5N. Hydrated antimony pentoxide is the best sorbent for²²³Ra. Incorporated in a composite exchanger, it could be used for decontamination purposes.     

Chromium antimonate as an ion-exchanger

Summary Chromium antimonate has been synthesised under varying conditions of precipitation and the cation-exchange properties of the various samples are reported. Systematic study has resulted in a product suitable for column operations. The effect of equilibration time, concentration of the electrolyte, size and charge of the ion and drying temperature on exchange capacity is reported. The chemical stability and regeneration power of the sample are also investigated. The plots of log K_d against pH for Rb⁺, Cs⁺, Tl⁺, Ca²⁺, Zn²⁺, and Tl³⁺ ions suggest a predominently ion-exchange mechanism in the case of Rb⁺ and Cs⁺ ions. K_d values of 27 metal ions have been determined and some chromatographic separations of analytical and radiochemical importance based on them have been achieved on chromium antimonate columns.Presented at the Annual Convention of Chemists (India), Roorkee, December 1975.     

Ion-exchange properties of titanic antimonate

Samples of titanic antimonate have been prepared under varying conditions of precipitation, and their properties, compositions and ion-exchange behaviours and the effect of γ-radiation and reported. Some topical separations have been performed using this material.