Angad Kumar Singh

Complexes of some 4f metal ions of the mesogenic Schiff-base, N,N′-di-(4-decyloxysalicylidene)-1′,3′-diaminobenzene: synthesis and spectral studies

A mesogenic Schiff-base, N,N′-di-(4-decyloxysalicylidene)-1′,3′-diaminobenzene, H2ddsdbz (abbreviated as H2L), that exhibits a nematic mesophase was synthesized and its structure was studied by elemental analysis, mass spectrometry, NMR, and IR spectral techniques. The Schiff-base, H2L, upon condensation with hydrated lanthanide(III) nitrates yields LnIII complexes, [Ln2(LH2)3(NO3)4](NO3)2, where Ln = La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, and Ho. Analyses of the IR and NMR spectral data imply bidentate Schiff-base through two phenolate oxygen atoms in its zwitterionic form to LnIII, rendering the overall geometry of the complexes as a seven-coordinate polyhedron – possibly distorted mono-capped octahedron. Polarizing optical microscope and differential scanning calorimetry studies reveal that despite H2L being mesogenic, none of the LnIII complexes synthesized under this study exhibits mesomorphism.

Rare Earth Metal Complexes of a Mesogenic Schiff-Base, N,N′-di-(4-decyloxysalicylidene)-1′, 4′-diaminobutane: Synthesis and Characterization

A mesogenic Schiff-base, N,N′-di-(4-decyloxysalicylidene)-1′,4′-diaminobutane, (H2L) that exhibits smectic-B and nematic mesophases, was synthesized and its structure studied by elemental analysis, mass spectrometry, NMR & IR techniques. H2L, upon condensation with hydrated lanthanide(III) nitrates yields LnIII complexes of the composition [Ln2(LH2)3(NO3)4](NO3)2, where LnIII = La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, and Ho. The PrIII complex shows smectic-A and nematic phases. The IR and NMR spectral data imply a bidentate bonding of H2L in zwitterionic form (as LH2) to the LnIII ions through two phenolate oxygen atoms, rendering the overall geometry of the complexes possibly to distorted mono-capped octahedra.

Synthesis, Spectral and Electrochemical Studies of Co(II) and Zn(II) Complexes of a Novel Schiff base Derived from Pyridoxal

A novel Schiff-base, N − (4- n -butyl)phenylpyridoxaldimine (Hbppyr), was prepared and structurally characterized on the basis of elemental analyses, and mass, NMR & IR spectral data. Hbppyr was found to coordinate through the azomethine nitrogen and phenolate oxygen in [M(bppyr) 2 (H 2 O) 2 ].nH 2 O where M = Co and Zn; non-coordination through pyridine nitrogen was implied by the IR spectral data as well as by the cyclic voltammograms of Hbppyr in its free and complexed forms. Pyridoxal-derived ligands have been continuously attracting the attention of number of scientists, mainly for the evolution of iron chelators for the treatment of iron overload disease and cancer. [1–6] Recently, some important review articles appeared on specifically pyridoxal isonicotinoyl hydrazone (PIH) and its analogs in relation to its potential orally effective iron-chelating ability for the treatment of iron overload disease. [1,2] As a part of our systematic investigation[ 7 , 8 ] on 3 d and 4 f metal complexes of some novel Schiff base ligands, we report here the synthetic and spectral studies on Co(II) and Zn(II) complexes of pyridoxal-drived Schiff base, (4- n -butyl)phenylpyridoxaldimine (Hbppyr), 1.

Structural Elucidation and Molecular Docking of a Novel Antibiotic Compound from Cyanobacterium Nostoc sp. MGL001.

Cyanobacteria are rich source of array of bioactive compounds. The present study reports a novel antibacterial bioactive compound purified from cyanobacterium Nostoc sp. MGL001 using various chromatographic techniques viz. thin layer chromatography (TLC) and high performance liquid chromatography (HPLC). Further characterization was done using electrospray ionization mass spectroscopy (ESIMS) and nuclear magnetic resonance (NMR) and predicted structure of bioactive compound was 9-Ethyliminomethyl-12-(morpholin - 4 - ylmethoxy) -5, 8, 13, 16–tetraaza–hexacene - 2, 3 dicarboxylic acid (EMTAHDCA). Structure of EMTAHDCA clearly indicated that it is a novel compound that was not reported in literature or natural product database. The compound exhibited growth inhibiting effects mainly against the gram negative bacterial strains and produced maximum zone of inhibition at 150 μg/mL concentration. The compound was evaluated through in silico studies for its ability to bind 30S ribosomal fragment (PDB ID: 1YRJ, 1MWL, 1J7T, and 1LC4) and OmpF porin protein (4GCP, 4GCQ, and 4GCS) which are the common targets of various antibiotic drugs. Comparative molecular docking study revealed that EMTAHDCA has strong binding affinity for these selected targets in comparison to a number of most commonly used antibiotics. The ability of EMTAHDCA to bind the active sites on the proteins and 30S ribosomal fragments where the antibiotic drugs generally bind indicated that it is functionally similar to the commercially available drugs.

Synthesis and spectral studies of some rare earth metal complexes of a heterocyclic mesogenic Schiff-base

ABSTRACT A heterocyclic liquid crystalline Schiffs base, N-(4′-(4″-hexyl-1H-1″,2″,3″-triazol))-4-dodecyloxysalicylaldimine (HL), and a series of lanthanide(III) complexes of the type [Ln(LH)3(NO3)3] (LnIII = La, Pr, Nd, Sm, Eu, Tb, and Dy) have been synthesized and characterized by elemental analyses, mass spectrometry, FTIR, NMR, and UV-Vis spectral techniques. All the complexes involve binding of HL (through phenolate oxygen in zwitter-ionic form) and bidentate chelation of nitrato groups. The ligand exhibits smectic-A (SmA) mesophase over a wide temperature range as evidenced by DSC and polarizing optical microscopic studies. Fluorescence studies show emissions of HL and TbIII complex.