- Effect of metallic dopants on potassium acid phthalate (KAP) single crystals
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Optically transparent single crystals of Cu2+ and Zn2+ doped potassium acid phthalate (KAP) were grown in aqueous solution by slow evaporation technique at room temperature. Single crystal X-ray diffraction analysis confirmed the changes in the lattice parameters of the doped crystals. The presence of functional groups in the crystal lattice has been determined qualitatively by Fourier transform infrared (FTIR) analysis. Optical absorption studies revealed that the doped crystals possess very low absorption in the entire visible region. The dielectric constant has been studied as a function of frequency for the doped crystals at temperatures viz., 328, 348, 368 K. Further the influence of metal dopants on the dielectric behaviour has been studied which clearly exhibited the ferroelectric properties of the crystal.
- Chithambaram,Jerome Das,Arivudai Nambi,Srinivasan,Krishnan
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- Synthesis and characterization of unique new lithium, sodium and potassium coordination polymers
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Five new alkali metal coordination compounds [Li(NPG)](1a), [Na(NPG)2]?2H2O(2a), [C8H5KO4](3a), [Li(NPA)2H2O](1b) and [Na(NPA)2](2b) wherein (NPG = N-phthaloyl glycine, NPA = N-phthaloyl-?-alanine) have been synthesized and characterized by means of X ray single crystal analysis, Infrared spectroscopy (IR), Thermogravimetric analysis (TGA) and Florescence spectroscopy. The compounds 1a, 2a, 3a and 2b showed metal directed self-assembly supramolecular network structures. The crystal structure of compounds 1a and 1b showed distorted tetrahedral geometry with coordination number 4 around lithium. The carboxylate coordination modes were η2μ3and η1μ1 in 1a and 1b respectively. The compounds 2a and 2b exhibited distorted octahedral geometry with coordination number 6 around sodium. The carboxylate coordination mode in 2a and 2b is η2μ2. The objective was to synthesize potassium complex [K(NPG)], but N-phthaloyl glycine was hydrolysed due to exothermic reaction in the presence of strong base, resulted, the formation of 3a. The multiple coordination modes of alkali metal ions to the carboxylate and ring carbonyl oxygen atoms of NPG and NPA produced unique three dimensional architectures. The compounds 1b and 2b showed two strong fluorescence emissions enhancement (blue emission maxima) with greater intensity comparative to NPA, while the compounds 1a and 2a showed two weak fluorescence emissions with less intensity comparative to ligand (NPG). The base hydrolysis of NPG with in the compound 3a resulted the change of ligand based fluorochrome, which produced different shape emission spectrum as compared to other compounds.
- Nadeem, Muhammad,Bhatti, Moazzam H.,Yunus, Uzma,Mehmood, Mazhar,Asif, Hafiz Muhammad,Mehboob, Shoaib,Fl?rke, Ulrich
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p. 179 - 188
(2018/05/09)
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- Facile and direct synthesis of symmetrical acid anhydrides using a newly prepared powerful and efficient mixed reagent
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An efficient mixed reagent for direct synthesis of symmetrical carboxylic anhydrides from carboxylic acids has been prepared. Carboxylic acids are converted to anhydrides using triphenylphosphine/ trichloroisocyanuric acid under mild reaction conditions at room temperature. Short reaction time, excellent yields of products, low cost, availability of reagents, simple experimental procedure, and easy work-up of the products are the main advantages of the presented method.
- Rouhi-Saadabad, Hamed,Akhlaghinia, Batool
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p. 479 - 485
(2015/01/30)
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- A New Method for Obtaining Isotopic Fractionation Data at Multiple Sites in Rapidly Exchanging Systems
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A new method for rapidly and conveniently obtaining isotopic fractionation factors in dilute aqueous solutions of compounds containing rapidly exchanging OH, NH, and SH groups is described.Shifts in the positions of NMR peaks for spectroscopically observable nuclei induced by isotopic substitution are the basis of this procedure which has the unique capability of separately measuring the isotopic exchange constants simultaneously for several different groups in the same molecule.The results for a series of alcohols, amines, thiols, phenols, acids, and amides with use of 13C NMR spectroscopy are reported.Atypically low values of Kfrac are observed in several cases, indicating that there are strong internal hydrogen bonds in competition with those to water, yielding conformational information.
- Jarret, Ronald M.,Saunders, Martin
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p. 2648 - 2654
(2007/10/02)
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