• M Nethaji

      Articles written in Journal of Chemical Sciences

    • Structure of isopropyl-N-phenyl carbamate—a plant hormone

      M Nethaji Vasantha Pattabhi

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      The structure of isopropyl-N-phenylcarbamate was solved by direct methods and refined to anR of 0·123 for 455 observed reflections. The molecule is stabilised by N-H ... O hydrogen bonds (2·873A). The angle between the phenyl ring and the carbamate group is 31(4)°. Charge density calculations were carried out on this molecule using the Huckellcaomo method for π charges and the DelRe method for ϕ charges. The charge separation between the ring atom with a net positive charge and the tail methyl group carbons are 5·53 and 5·83 A.

    • Crystal structure of hirudonine sulphate—a rare polyamine

      M Nethaji Vasantha Pattabhi

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      Hirudonine sulphate (C9H23N7. 1·5 H2SO4. 2·5 H2O) is triclinic inPI space group with cell constantsa=7·168(9),b=14·534(6),c=11·918(5) Å, α=110·50(3), β=108·75(6) and γ=79·16(6)°,V=1097(2)Å3,Mr=421·4,Z=2,dx=1·358(2) gcm−3,dc=1·276 gcm−3. MoKα (λ=0·7903 Å), μ=1·94 cm−1,F(000)=436,T=295 K,R(F)=0·144. The structure was solved by direct methods and refined to a final R factor of 0·144 for 1036 unique reflections. One of the sulphur atoms is in special position and is disordered. The amine molecule is hydrogen-bonded to the sulphate oxygen through water molecules. Water channels are formed at unique places involving water oxygens, amine and sulphate oxygens along thea axis.

    • Structure of 3-ethyl-6-phenyl-4-carbomethoxy-l·H-2-pyridone, an anti-tubercular metabolite

      M Nethaji Vasantha Pattabhi E J Gabe

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      C15H15N03,Mr=257·28, rhombohedral, R≈3,a=40·510(4),c=4·5456(3)Å,V=6460(2)Å,Z=18,dc=1·1905(3)g/cm3, CuKα(λ=1·5418Å), μ= 6·5cm−1,F(000)=2448,T=295K, finalR(F)=0·091,wR=0·141 for 1425 significant reflections,I≤2·5 σ(I). The molecules are stacked along thec axis and are stabilized in the unit cell by N−…O and C−H…O types of hydrogen bonds. Centrosymmetrically related molecules form dimers about the centre of inversion, and the hydrogen bond pattern is reminiscent of pyrimidine-purine base pairing in nucleotides.

    • Synthetic, spectroscopic and structural investigations on actinide complexes of diphosphazane dioxides

      K Aparna S S Krishnamurthy M Nethaji

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    • Isomers of β-substituted di and tri-nitrotetraphenylporphyrins and their copper(II) derivatives: Structure, optical and electrochemical redox properties

      S Dahal V Krishnan M Nethaji

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      Controlled nitration ofmeso-tetraphenylporphyrinatocopper(II) using fuming nitric acid leads to the formation of different β-substituted nitro derivatives. Five isomers of dinitro and three isomers of trinitrotetraphenylporphyrins have been isolated and characterised using FAB/MS,1H NMR, UV-VIS and IR spectroscopies. The single crystal X-ray data on the copper(II) derivative of one of the isomers of trinitrotetraphenylporphyrin revealed ‘saddle’ conformation of the porphyrin core resulting from the nitro group substitution at theβ-pyrrole carbons. The electrochemical redox behaviour of the free-base porphyrins and their copper(II) derivatives revealed that successive substitution of nitro groups at the pyrrole carbons shifts the one-electron ring oxidations anodically while the ring reduction occurs at a less cathodic potential relative to the unsubstituted porphyrin. The isomer specific shifts in the redox potentials bear a direct relationship with the relative energy levels of HOMO/LUMO obtained from AM1 calculations.

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