• Jubaraj B Baruah

      Articles written in Journal of Chemical Sciences

    • 1-Phenyl-3-(quinolin-5-yl)urea as a host for distinction of phthalic acid and terephthalic ac

      Dipjyoti Kalita Jubaraj B Baruah

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      Co-crystals of 1-phenyl-3-(quinolin-5-yl)urea (1) with terephthalic acid, adipic acid; and salts of 1 with phthalic acid, 𝑝-toluenesulphonic acids are prepared and structurally characterized. The reaction of phthalic acid and 𝑝-toluenesulphonic acid resulted in protonation of the host 1, whereas the terephthalic acid and adipic acid interact with 1, led to cocrystals with the host 1 through hydrogen bond interactions. The hydrogen bonds that appears in the urea taps of the host molecules 1 are lost while formation of salts; in such cases anions interacts with the urea portion of the host, while in the co-crystals the hydrogen bonded urea taps are retained. The salts are yellow in colour while the co-crystals are colourless; thereby the positional isomer phthalic acid can be distinguished from the terephthalic acid.

    • Anion-𝜋 interactions in layered structures of salts of 5-(hydroxyimino) quinolin-8-one and related salts

      Prithiviraj Khakhlary Jubaraj B Baruah

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      Relevance of anion-𝜋 interactions in chloride, bromide, nitrate and perchlorate salts of 5-(hydroxyimino)quinolin-8-one are discussed. Structures of nitrate salt of 5-aminoquinoline as well as nitrate salt of 4-hydroxyquinazoline are compared with the structure of nitrate salt of 5-(hydroxyimino)quinolin-8-one. From such a comparison, two different arrangements of nitrate ions with respect to the respective cations are discerned. Nitrate ions are sandwiched between aromatic planes of cations in nitrate salts of 5-(hydroxyimino)quinolin-8-one or 4-hydroxyquinazoline; whereas, nitrate ions are in oblique positions with respect to aromatic planes of counter cations in nitrate salt of 5-aminoquinoline. Binding constants of different nitrate salts in solution are determined by UV-visible spectroscopic titrations. Solution study shows formation of ion-pairs of these salts in solution.

    • Studies on cluster, salt and molecular complex of zinc-quinolinate

      Prithiviraj Khakhlary Jubaraj B Baruah

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      Reactions of zinc halides with 8-hydroxyquinoline (hydroxQ) in equimolar ratio were carried out in different solvents. Respective solvates of tetranuclear clusters, namely [Zn4(oxyQ)6X2].(solvent)2, (when X=Cl, Solvent=dimethylformamide (1), dimethylacetamide (2) and dimethysulphoxide (3); X = Br, solvent = dimethylformamide (4), oxyQ=quinolinate anion) were obtained. Bond parameters of these isostructural clusteres 1–4 are compared from their single crystal structures. Anhydrous form of the cluster have porous packing and is thermally stable below 250° C. Surface area of the clusters 1 and 4 are 8.933 and 6.172 m2/g, respectively. Complexes 1 and 4 can be reversibly hydrated, which is reflected in colour changes. The reaction of zinc chloride with 8-hydroxyquinoline in equimolar ratio followed by crystallization from water gave salt (HhydroxQ)2 [ZnCl4] (5) and a similar reaction followed by crystallization from 3-methylpyridine (3mepy) resulted in the molecular complex [Zn(oxyQ)2(3mepy)]. [Zn(oxyQ)2(3mepy)2].3H2O (6). Complex 5 is formed from a hydrolytic equilibrium of water with zinc chloride yielding tetrachloro zinc anion and zinc hydroxide. Taking advantage of this reaction, a composite material of ZnO@complex 5 exhibiting dual fluorescence at 450 and 575 nm on excitation at 390 nm was prepared. Fluorescence emission properties of all the complexes in solid state are compared with fluorescence emission of the ligand

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