• Volume 120, Issue 3

May 2008,   pages  295-351

• Note on plagiarism

• Non-covalent O$\cdots$O interactions among isopolyanions using a cis-{MoO2} moiety by the assistance of N-H$\cdots$O hydrogen bonds

An inorganic-organic hybrid material, [2-AmpH]4[Mo8O26] (1) has been isolated by the reaction of Na2MoO$_4·2$H2O with 2-aminopyrimidine (2-Amp) from an acidic aqueous medium. In this low pH synthesis, the organic molecule (2-Amp) gets mono-protonated (2-AmpH+) and acts as the cation in stabilizing the octamolybdate anion in 1. Compound 1 crystallizes in the triclinic space group 𝑃-1 with 𝑎 = 9.925(3), 𝑏 = 10.020(3), 𝑐 = 10.414(3) Å, 𝛼 = 88.811(4), 𝛽 = 64.907(4), 𝛾 = 89.506(4)°, 𝑍 = 1. An interesting three-dimensional supramolecular structure, having well-defined channels, is formed through N-H$\cdots$O and C-H$\cdots$O hydrogen bonds, in which the protonated organic cation plays a significant role. The crystal structure also reveals an unusual cluster-cluster (non-covalent O$\cdots$O) interaction using cis-(MoO2} moieties of the isopolyanion. N-H$\cdots$O hydrogen bonds, originated from pyridimidinium cation and isopolyanion, are found to influence to attain such non-covalent O$\cdots$O interactions among polyoxometalate anions. An interesting helical arrangement, formed from isopolyanion and organic cation, is observed.

• Tris(dithiocarboxylato)indium(III): Thermal studies and crystal structure of [In(S2Ctol)3]

Tris(dithiocarboxylato)indium(III), [In{S2CAr}3] (Ar = phenyl or 𝑝-tolyl) have been synthesized and characterized. The molecular structure of [In(S2Ctol)3] established by single crystal X-ray diffraction revealed a distorted octahedral geometry with symmetrically chelating dithiocarboxylate groups. These complexes on thermolysis gave 𝛽-In2S3 which was characterized by XRD and EDX.

• Preparation, crystal structure, and characterization of an inorganic-organic hybrid polyoxoniobate [Cu(en)2]3[Cu(en)2(H2O)]1.5[K0.5Nb24O72H14.5]2.25H2O

An inorganic-organic hybrid polyoxoniobate compound [Cu(en)2]3[Cu(en)2(H2O)]1.5 [K0.5Nb24O72H14.5]2.25H2O (1) was synthesized by reaction of K7HNb6O$_{19}.13$H2O, Cu(CH3COOH)$_2.$H2O and en (ethylenediamine) in aqueous solution and characterized by IR, ESR spectroscopy and singlecrystal X-ray diffraction method. Structure analysis indicates that compound 1 consists of a new type polyoxoniobate anion [K0.5Nb24O72H14.5]9-, three [Cu(en)2]2+, one point five [Cu(en)2(H2O)]2+, and two point two five crystal water molecules. The structure contains N-H$\cdots$O hydrogen bonds between the coordinated ethylenediamine and the polyniobate-anion. The whole molecule possesses the $C_{3v}$ symmetry.

• Density functional theory study of vibrational spectra, and assignment of fundamental modes of dacarbazine

The FTIR and FT Raman spectra of dacarbazine were recorded in the regions 4000-400 and 3500-100 cm-1, respectively. The optimized geometry, wavenumber, polarizability and several thermodynamic properties of dacarbazine were studied using ab initio Hartree-Fock, MP2 and DFT methods. A complete vibrational assignment aided by the theoretical harmonic wavenumber analysis was proposed. The calculated harmonic vibrational frequencies were compared with experimental FTIR and FT Raman spectra. Based on the comparison between calculated and experimental results and the comparison with related molecules, assignments of fundamental vibrational modes were made. The X-ray geometry and experimental frequencies were compared with the results of theoretical calculations.

• Guest-host interactions in the cleavage of phenylphenyl acetates by 𝛽-cyclodextrin in alkaline medium

Kinetics of cleavage of phenylphenyl acetates (PPA) and several para-substituted PPAs in basic aqueous sodium carbonate-bicarbonate buffer containing 𝛽-cyclodextrin (CD) have been studied. The reaction exhibits saturation type kinetics and CD accelerates the rate of cleavage by the formation of 1G : 1H inclusion complex. The kinetic results indicate that aryloxy moiety of PPA is included in the hydrophobic cavity of CD. The overall rate constants for the cleavage of the [CD-ester] complex correlate with the Hammett 𝜎-constants and Hansch hydrophobicity parameters 𝜋. At higher concentrations of CD, there is an additional catalysis due to the formation of weak 1G : 2H complex.

• The ribose and glycine Maillard reaction in the interstellar medium (ISM): A theoretical study

Possibility of the Maillard reaction to take place in the gaseous phase in the interstellar medium was investigated by using Density Functional Theory (DFT) computations. Cyclic ribose (c-Rib)/open-chain ribose (c-Rib) and glycine were taken as the model. Mechanisms have been proposed, and possibility of the formation of different compounds have been evaluated through calculating the Gibb’s free energy changes for different steps of the reaction by following the total mass balance. The result reveals that both c-Rib and Rib can participate in the reaction, and c-Rib is more efficient than Rib. The reactions under basic and neutral conditions are supposed to be the first and second most favourable. Acidic conditions and the isoelectric point of glycine were unfeasible for the reaction. The kinetics of the mechanics are briefly addressed in this work.

• 𝛽-Enaminonitriles in heterocylic synthesis: Synthesis of new tetrahydropyridinethione, pyridopyrimidines, pyridotriazines and dihydropyridines

The chemistry of enaminonitrile and enaminone derivatives has been explored for the synthesis of heterocyclic compounds. A tetrahydropyridinthione was prepared from the reaction of 2-aminocrotononitrile with cyanothioacetamide. This compound reacted with electrophilic reagents and isothiocyanates to yield a number of heterocyclic compounds.

• Microwave-assisted efficient oxidation of internal alkynes to 1,2-diaryldiketones with DMSO/I2

This paper reports the oxidation of functionalized internal alkynes with DMSO in the presence of I2 under microwave irradiation. This procedure gave 1,2-diaryldiketones in good yields.

• # Journal of Chemical Sciences

Volume 132, 2019
All articles
Continuous Article Publishing mode

• # Editorial Note on Continuous Article Publication

Posted on July 25, 2019