G. Rajagopal

Synthesis and spectral characterization of Schiff base complexes of Cu(II), Co(II), Zn(II) and VO(IV) containing 4-(4-aminophenyl) morpholine derivatives: Antimicrobial evaluation and anticancer studies

Metal(II) chelates of Schiff bases derived from the condensation of 4-morpholinoaniline with substituted salicylaldehyde have been prepared and characterized by (1)H NMR, IR, electronic, EPR, and magnetic measurement studies. The complexes are of the type M(X-MPMP)2 [where M=Cu(II), Co(II)), Zn(II), or VO(IV); MPMP=2-[(4 morpholinophenyl imino) methyl] 4-X-phenol, X=Cl, (L1H), X=Br (L2H)]. Single crystal X-ray crystallography studies confirm the structure of newly synthesized Schiff bases. The Schiff bases act as bidentate monobasic ligands, coordinating through deprotonated phenolic oxygen and azomethine nitrogen atoms. The free ligands and metal complexes are screened for their biopotency. Metal complexes exhibit better activity than ligands. Anticancer activity of ligands and their metal complexes are evaluated in human heptocarcinoma(HepG2) cells. The preliminary bioassay indicates that the Schiff base and its zinc complex exhibit inhibitory activity against the human gastric cancer cell lines.

Natural alkaloid Luotonin A and its affixed acceptor molecules: Serum albumin binding studies

Effective interaction of natural alkaloid Luotonin A (L) and its affixed acceptor molecules 1 and 2 with donor molecule as Bovine serum albumin (BSA) at various pH (4.0, 7.4 and 10.0) medium have been demonstrated using various conventional spectroscopic techniques. These analyses provide some valuable features on the interaction between BSA and acceptor molecules (L, 1 and 2). From the absorption and fluorescence spectral titration studies, the formation of ground-state complexes between the acceptor molecules (L, 1 and 2) and the BSA have been confirmed. The results of the afore titrations analysis reveal that, the strong binding of receptor 1 with BSA (Kapp 5.68×104M-1; KSV 1.86×106Lmol-1; Ka 6.42×105Lmol-1; Kass 8.09×106M-1; ΔG -33.35kJ/mol) at physiological pH medium (7.4) than other receptor molecules 2 and L. The Förster resonance energy transfer (FRET) efficiency between the tryptophan (Trp) residues of BSA and acceptor molecules L, 1 and 2 during the interaction, are 28.85, 85.24 and 53.25 % respectively. The superior binding efficacy of acceptor 1 at physiological pH condition has been further confirmed by FT-IR and Raman spectral analysis methods. Moreover, theoretical docking studies of acceptors L, 1 and 2 towards HSA have been demonstrated to differentiate their binding behaviours. It reveals that, acceptor 1 has the strongest binding ability with HSA through two hydrogen bonding and the Atomic contact energy (ACE) value of -483.96kcal/mol.

Synthesis, characterization, crystal structure and cytotoxic properties of thiosemicarbazide Ni(II) and Zn(II) complexes

Synthesis of new complexes of Ni(II) (1) and Zn(II) (2) with [1-(2-hydroxy-3,5-diiodobenzylidene)-4-phenylthiosemicarbazide] have been reported. The composition of these two complexes 1 and 2 is discussed on the basis of IR, (1)H NMR and UV spectral data along with their X-ray crystallographic data. The crystal structure of these two complexes has revealed that the free ligand (L) is deprotonated twice at the oxygen and sulfur atoms and they are coordinated with the complexes through phenoxide-O, azomethine-N and thiolate-S atoms. The single-crystal X-ray structures of complex (1) exhibits a square planar structure, while complex (2) reveals trigonal bipyramidal distorted square based pyramidal structure. Anticancer activity of ligand and the complexes 1-2 are evaluated in human adenocarcinoma (MCF-7) cells. The preliminary bioassay indicates that the free ligand and the complexes 1-2 exhibit inhibitory activity against the human adenocarcinoma cancer cell lines.

N'-[(E)-2-Hy-droxy-3,5-diiodo-benzyl-idene]pyridine-3-carbohydrazide.

In the title compound, C13H9I2N3O2, the dihedral angle between the two aromatic rings is 10.5 (2)°. The molecule displays a trans configuration with respect to the C=N bond. An intramolecular O—H⋯N hydrogen bond occurs. The crystal packing is stabilized by N—H⋯O and C—H⋯O hydrogen bonds.

Crystal structure of (E)-5-di-ethyl-amino-2-({[4-(di-methyl-amino)-phen-yl]imino}-meth-yl)phenol.

The title Schiff base compound, C19H25N3O, is approximately planar, with a dihedral angle of 9.03 (13)° between the planes of the aromatic rings, and has an E conformation about the N=C bond. The molecular structure is stabilized by an intramolecular O—H⋯N hydrogen bond, with an S(6) ring motif. In the crystal, molecules are linked by C—H⋯π interactions, forming sheets parallel to the bc plane.

(E)-N′-(3-Bromo-5-chloro-2-hy­droxy­benzyl­idene)nicotinohydrazide

There are two independent molecules in the asymmetric unit of the title compound, C13H9BrClN3O2, in which the dihedral angles between the benzene and pyridine rings are 8.23 (9)° and 52.84 (12)°. Both the molecules exist in an E configuration with respect to the C=N double bond. The two molecules in the asymmetric unit are linked via weak C—H⋯O hydrogen bonds. In both the molecules, an intramolecular O—H⋯N hydrogen bond generate an S(6) graph-set motif. In the crystal, intermolecular N—H⋯O and C—H⋯O hydrogen bonds generate bifurcated R 1 2(7) ring motifs. The crystal packing is further stabilized by weak intermolecular N—H⋯O, N—H⋯N, C—H⋯O and π–π [centroid–centroid distance 3.615 (2) Å] interactions.

A theranostic nanocomposite system based on iron oxide-drug nanocages for targeted magnetic field responsive chemotherapy

In this work, a theranostic nanocage system was developed for the targeted delivery of the anti-cancer agents camptothecin (CPT) and luotonin A (LuA). The core of the nanocage system (Fe3O4@OA-AD-SP NCs) was formed by biogenically synthesized Fe3O4 nanoparticles (NPs) decorated with a model anti-cancer drug (AD) and biosurfactant saponin (SP). The Fe3O4@OA-AD-SP NCs showed a high lipophilic AD loading efficiency (>80%) and a controlled pH-responsive drug release in stimulated cancerous cells in pH 6.4 media buffer. In addition, Fe3O4@OA-AD-SP NCs exhibited better serum protein binding efficacy at physiological pH values (7.4), furthering the important role of SP surface decoration. Particularly, these NCs showed better chemotherapeutic efficacy when examined in MCF-7 and HeLa cancer cell lines with a specific targeting capacity. Therefore, this study provides a new nano platform based on magnetic targeting and pH responsive lipophilic anticancer drug delivery to the cancer site.

Crystal structure, optical properties, DFT analysis of new morpholine based Schiff base ligands and their copper(II) complexes: DNA, protein docking analyses, antibacterial study and anticancer evaluation

New morpholine derived Schiff base ligands (HL1 and HL2) and their Cu(II) complexes [Cu(L1)2] (1) and [Cu(L2)2] (2) have been synthesized and characterized by 1H NMR, IR, UV-Vis, EPR studies and cyclic voltammetric analyses. Single crystal X-ray crystallography studies confirm the structure of newly synthesized Schiff base ligands HL1and HL2. The ground state electronic structures of Cu(II) complexes 1 and 2 have been investigated by DFT/B3LYP theoretical analysis with 6-31G (d,p) and LANL2DZ basis set. The affinity towards DNA and protein molecules have been evaluated using computational docking analysis and complex 2 expose significant binding ability with DNA as well as protein due to its towering hydrophobicity. Consequently, complex 2 reveals superior antibacterial activity against some bacterial species besides anticancer activity on human breast cancer (MCF-7) cells than complex 1 and Schiff base ligands (HL1 and HL2). These preliminary investigations strongly recommended that complex 2 can be used as a better antibacterial plus anticancer agent.

Crystal structure of 5-diethylamino-2-({[4-(diethylamino)phenyl]imino}methyl)phenol

In the title compound, C21H29N3O, the dihedral angle between the planes of the aromatic rings is 8.1 (2)°. The ethyl groups at one terminal site of the compound are disordered over two sets of sites with occupancies of 0.775 (9) and 0.225 (9). The molecule has an E conformation about the N=C bond. The molecular structure features an intramolecular O—H⋯N hydrogen bond, which closes an S(6) loop. In the crystal, weak C—H⋯π interactions leads to the formation of a three-dimensional network.

Crystal structure of [1-(3-eth­oxy-2-oxido­benzyl­idene-κO2)-4-phenyl­thio­semicarbazidato-κ2N1,S](tri­phenylphosphane-κP)nickel(II)

In the title complex, [Ni(C16H15N3O2S)(C18H15P)], the NiII atom has a distorted tetrahedral coordination geometry, comprised of N, S, O and P atoms of the tridentate thiosemicarbazide ligand and the P atom of the triphenylphosphane ligand. The benzene ring makes a dihedral angle of 53.08 (11)° with the phenyl ring of the phenylthiosemicarbazide moiety and dihedral angles of 73.69 (11), 20.38 (11) and 71.30 (11)° with the phenyl rings of triphenylphosphane ligand. A pair of N—H⋯N hydrogen bonds generates an R 2 2(8) ring graph-set motif. The ethoxy group is disordered over two positions, with site occupancies of 0.631 (9) and 0.369 (9). The molecular structure is stabilized by a weak intramolecular C—H⋯O hydrogen bond. In the crystal, weak N—H⋯N and C—H⋯π interactions connect the molecules, forming a three-dimensional network.