Mixed-ligand and binuclear complexes of oxovanadium(IV)

Summary Mixed ligand complexes of the type [VOLA]ClO₄ where L=5-bromosalicylaldehyde (L) or 5-nitrosalicylaldehyde (L) and A=2, 2-dipyridyl (A) or 1, 10-phenanthroline (A) have been prepared. Treatment of the mononuclear complexes, [VOLA]ClO₄, withp-phenylenediamine (ppd) orm-phenylenediamine (mpd) yielded homobinuclear [VOLA-NC₆H₄N-LAVO](ClO₄)₂, complexes, which were characterised by elemental analyses, spectra, magnetic susceptibility and molar conductance measurements.     

UV-Vis, fluorescence and NMR spectroscopic investigations on inclusion properties of a designed tetrahomocalix[8]arene with fullerenes C60 and C70 in solution

The present article reports the spectroscopic investigations on non-covalent interaction of fullerenes C(60) and C(70) with a macrocyclic receptor molecule, namely, 1,3,5,7-tetrahomo-p-tert-butylcalix[8]arene (1) in toluene. Jobs method of continuous variation reveals 1:1 stoichiometry for the fullerene complexes of 1. The most fascinating feature of the present study is that 1 binds selectively C(60) compared to C(70) as obtained from binding constant (K) data of C(60)-1 (K(C60-1)) and C(70)-1 (K(C70-1)) complexes which are enumerated to be 265,000 dm(3) mol(-1) and 63,43 dm(3) mol(-1), respectively, and selectivity in binding (K(C60-1)/K(C70-1)) is estimated to be 4.18 as obtained from UV-Vis study. Steady state fluorescence studies reveal quenching of fluorescence of 1 in presence of fullerenes and the K value of the C(60)-1 and C(70)-1 complexes are estimated to be 80,760 and 68,780 dm(3) mol(-1), respectively, with selectivity in binding (K(C60-1)/K(C70-1)) ~1.18. (1)H NMR analysis provides very good support in favor of strong binding between C(60) and 1. The high value of K value for C(60)-1 complex indicates that 1 forms an inclusion complex with C(60).     

Copper(I) complexes of N-(aryl)pyridine-2-aldimines: Spectral, electrochemical and catalytic properties

The reactions of N-(aryl)pyridine-2-aldimines (L-R; R = OCH₃, CH₃, H, Cl and NO₂), derived from pyridine-2-aldehyde and para-substituted anilines, with CuI in methanol under ambient conditions afford a series of brown complexes of the type [{Cu(L-R)I}₂]. The structure of the [{Cu(L-OCH₃)I}₂] complex has been determined by X-ray crystallography. In these dimeric complexes the two copper centers are linked through an iodo-bridge, and the L-R ligands are coordinated to the metal center through the pyridine-nitrogen and imine-nitrogen. All the complexes show characteristic ¹H NMR signals and intense MLCT transitions in the visible region. These complexes also show an emission near 465 nm, whilst they are excited at 340 nm, with relatively poor quantum yields (φ ∼0.002 at 298 K). Cyclic voltammetry on all the complexes shows two successive Cu(I)-Cu(II) oxidations on the positive side of SCE, and a reduction of the coordinated imine ligand on the negative side. These copper(I) complexes are found to efficiently catalyze Suzuki type C-C coupling reactions.     

Physicochemistry of interaction between the cationic polymer poly(diallyldimethylammonium chloride) and the anionic surfactants sodium dodecyl sulfate, sodium dodecylbenzenesulfonate, and sodium N-dodecanoylsarcosinate in water and isopropyl alcohol-water media

The physicochemistry of interaction of the cationic polymer poly(diallyldimethylammonium chloride) (PDADMAC) with the anionic surfactants sodium dodecyl sulfate, sodium dodecylbenzenesulfonate, and sodium N-dodecanoylsarcosinate was studied in detail using tensiometry, turbidimetry, calorimetry, viscometry, dynamic light scattering (DLS), and scanning electron microscopy (SEM). Fair interaction initially formed induced small micelles of the surfactants and later on produced free normal micelles in solution. The interaction process yielded coacervates that initially grew by aggregation in the aqueous medium and disintegrated into smaller species at higher surfactant concentration. The phenomena observed were affected by the presence of isopropyl alcohol (IP) in the medium. The hydrodynamic sizes of the dispersed polymer and its surfactant-interacted species were determined by DLS measurements. The surface morphologies of the solvent-removed PDADMAC and its surfactant-interacted complexes from water and IP-water media were examined by the SEM technique. The morphologies witnessed different patterns depending on the composition and the solvent environment. The head groups of the dodecyl chain containing surfactants made differences in the interaction process.     

Determination of binding strength for the supramolecular complexation of a designed bisporphyrin with C60, C70 and their derivatives employing absorption spectrophotometric, fluorescence and quantum chemical calculations

The present paper reports the synthesis of a designed bisporphyrin (1), and its supramolecular complexes with C60, C70 and their derivatives, namely, tert-butyl-(1,2-methanofullerene)-61-carboxylate (2) and [6,6]-phenyl C70 butyric acid methyl ester (3) in toluene medium. C60, C70 and their derivatives undergo ground state non-covalent interaction with 1 is evidenced from absorption spectrophotometric study in which it is observed that the intensity of the Soret absorption band of 1 decreases considerably in presence of C60, C70 and their derivatives. Steady state fluorescence studies reveal efficient quenching of fluorescence of 1 in presence of fullerenes. The binding constant (K) values of the fullerene/1 complexes follows the trend: 2/1相似文献   

Chemical modification of L-glutamine to alpha-amino glutarimide on autoclaving facilitates Agrobacterium infection of host and non-host plants: A new use of a known compound

Background

Accidental autoclaving of L-glutamine was found to facilitate the Agrobacterium infection of a non host plant like tea in an earlier study. In the present communication, we elucidate the structural changes in L-glutamine due to autoclaving and also confirm the role of heat transformed L-glutamine in Agrobacterium mediated genetic transformation of host/non host plants.

Results

When autoclaved at 121°C and 15 psi for 20 or 40 min, L-glutamine was structurally modified into 5-oxo proline and 3-amino glutarimide (α-amino glutarimide), respectively. Of the two autoclaved products, only α-amino glutarimide facilitated Agrobacterium infection of a number of resistant to susceptible plants. However, the compound did not have any vir gene inducing property.

Conclusions

We report a one pot autoclave process for the synthesis of 5-oxo proline and α-amino glutarimide from L-glutamine. Xenobiotic detoxifying property of α-amino glutarimide is also proposed.     

Multiplex digital PCR: breaking the one target per color barrier of quantitative PCR

Quantitative polymerase chain reactions (qPCR) based on real-time PCR constitute a powerful and sensitive method for the analysis of nucleic acids. However, in qPCR, the ability to multiplex targets using differently colored fluorescent probes is typically limited to 4-fold by the spectral overlap of the fluorophores. Furthermore, multiplexing qPCR assays requires expensive instrumentation and most often lengthy assay development cycles. Digital PCR (dPCR), which is based on the amplification of single target DNA molecules in many separate reactions, is an attractive alternative to qPCR. Here we report a novel and easy method for multiplexing dPCR in picolitre droplets within emulsions-generated and read out in microfluidic devices-that takes advantage of both the very high numbers of reactions possible within emulsions (>10(6)) as well as the high likelihood that the amplification of only a single target DNA molecule will initiate within each droplet. By varying the concentration of different fluorogenic probes of the same color, it is possible to identify the different probes on the basis of fluorescence intensity. Adding multiple colors increases the number of possible reactions geometrically, rather than linearly as with qPCR. Accurate and precise copy numbers of up to sixteen per cell were measured using a model system. A 5-plex assay for spinal muscular atrophy was demonstrated with just two fluorophores to simultaneously measure the copy number of two genes (SMN1 and SMN2) and to genotype a single nucleotide polymorphism (c.815A>G, SMN1). Results of a pilot study with SMA patients are presented.     

Synthesis and DNA binding studies of Ni(II), Co(II), Cu(II) and Zn(II) metal complexes of N1,N5-bis[pyridine-2-methylene]-thiocarbohydrazone Schiff-base ligand

The thiocarbohydrazone Schiff-base ligand with a nitrogen and sulphur donor was synthesized through condensation of pyridine-2-carbaldehyde and thiocarbohydrazide. Schiff-base ligands have the ability to conjugate with metal salts. A series of metal complexes with a general formula [MCl2(H2L)]·nH2O (MNi, Co, Cu and Zn) were synthesized by forming complexes of the N1,N5-bis[pyridine-2-methylene]-thiocarbohydrazone (H2L) Schiff-base ligand. These metal complexes and ligand were characterized by using ultraviolet-visible (UV-Vis), Fourier Transform Infrared (FT-IR), 1H and 13C NMR spectroscopy and mass spectroscopy, physicochemical characterization, CHNS and conductivity. The biological activity of the synthesized ligand was investigated by using Escherichia coli DNA as target. The DNA interaction of the synthesized ligand and complexes on E. coli plasmid DNA was investigated in the aqueous medium by UV-Vis spectroscopy and the binding constant (Kb) was calculated. The DNA binding studies showed that the metal complexes had an improved interaction due to trans-geometrical isomers of the complexes than ligand isomers in cis-positions.     

Synthesis of crescent shaped heterocycle-fused aromatics via Garratt-Braverman cyclization and their DNA-binding studies

Three crescent shaped heterocycle-fused phenanthrene based systems 1–3 have been synthesized starting from benzene (or substituted benzene) 1,2-bis-propargyl alcohols. Bis-alkylation with propargylic bromides provided the key intermediate, the bis-propargyl bis-ethers. In spite of the possibility of many competing reactions, the latter underwent facile double Garratt-Braverman cyclization to provide compounds 1–3 in near quantitative yield, in a striking reaction involving the formation of four C–C bonds in a single step. Compounds 1–3 showed binding interaction with DNA, predominantly, via groove binding along with partial intercalation (combilexins). Molecular docking study supported the proposed binding modes.