Late-stage Ligand Modification After Coordination Strengthens Stereoselectively Self-Assembled Hemiaminal Ether Complexes.

Fragile hemiaminal ether linkages present in the backbone of koneramines (LR OR'), tridentate ligands, bound to copper(II) in stereoselectively self-assembled syn-[Cu(LR OR')X2 ] complexes were transformed into sturdy methylene linkages to make corresponding rac-[Cu(LR H)Cl2 ] complexes by late-stage ligand modification after coordination with the retention of coordination sphere. The generality of stereoselective self-assembly of koneramine complexes is shown by utilising a number of metal ions, anions, amines, alcohols and thiols with complete characterisations.

Investigating the photosensitivity of koneramines for cell imaging and therapeutic applications.

The photophysical properties of the anthracene appended koneramines (LAn) were analyzed and utilized as a chemosensor for the selective detection of Cd2+ and Zn2+. The complexation-induced inhibition of PET (photo-induced electron transfer) from the chelating nitrogen atoms to the excited state of the anthracene moiety resulted in a fluorescence "turn-on" signal upon binding with Cd2+ and Zn2+. The confocal microscopic imaging studies performed on the MCF-7 cells validated that the compound is potentially useful for detecting Cd2+ and Zn2+ inside the cells. The cadmium complex exhibited unique bactericidal activity against clinically relevant human pathogens. The excellent activity against multidrug-resistant S. aureus makes the complex useful as a new, easily synthesizable antibiotic. The cadmium complex LAnCdCl2 was not cytotoxic against vero cells with a selectivity index of 40, exhibited concentration dependent bactericidal killing, was non-interactive with several other clinically approved standard drugs, exhibited prolonged post-antibiotic effect (PAE) against S. aureus ATCC 29213 and possesses antibiofilm activity.

Triazine based eccentric Piedfort units towards a single source hydrogen bonded network.

Herein we report a hydrogen-bonded three-dimensional network originating from a single source precursor, sym-triisopropylaminotriazine, that is both a donor and an acceptor of hydrogen bonds. The C3h symmetric design allowed the formation of intermolecular hydrogen bonds leading to helices in all three directions. The eccentric Piedfort units present in the framework with a distance of 8.15 Å between the two triazine rings allowed the CHCl3 guest to be parked.

Quick Microwave Assisted Synthesis and In Vitro Imaging Application of Oxygen Doped Fluorescent Carbon Dots.

In this paper, a fast and simplest one-pot tactic was used to synthesis fluorescent oxygen doped carbon dots from Tween-20 (TTO-CDs) is reported. The TTO-CDs were microwavically synthesized by using Tween-20 as both the carbon precursor and the oxygen dopant as well. The surface morphology, crystalline and/or amorphous nature, composition and optical assets of synthesized TTO-CDs were studied by means of existing techniques. From the results, it was confirmed that the as-synthesized TTO-CDs are amorphous in nature, monodispersed, sphere-shaped and the typical particle size range is 5 ± 1.5 nm. The synthesized TTO-CDs emits strong blue fluorescence at 390 nm under excitation of 335 nm. Most interestingly, the excitation dependent emission property of synthesized TTO-CDs was exposed from fluorescence results. The synthesized TTO-CDs have quantum yield of about 14% against quinine sulfate as reference standard. The biotoxicity of synthesized TTO-CDs on HeLa cells was assessed through cytotoxicity assay. These results implied that the fluorescent TTO-CDs showed less biotoxicity, and further which was efficaciously applied as a multicolor staining and bioimaging probe for the confocal imaging of HeLa cells.

Mechanism of Evolution of Koneramine Complexes from One-Pot Reactions: Snapshots of Intermediates Offer Facile Routes to New Dipicolylamines.

Koneramines (LR OR', R=Ph or Ts; R'=Me, iPr) and their complexes were found to emerge from the system of pyridine-2-carboxaldehyde and N-phenyl/tosylethylenediamine when a primary or secondary alcohol was used as solvent. Imidazolidinylpyridines (LR , R=Ph or Ts) became major emergents whereas hemi-aminals (LR OH, R=Ph or Ts) are minor emergents of the system when tertiary butanol was used as the solvent; the bulky tertiary butyl group prevented the addition of alcohol to the iminium ion that diverted the equilibrium towards imidazolidinylpyridines. By playing with the components of the reaction mixture, crystals of the metastable intermediates bound to copper(II) and/or zinc(II) were obtained and the structures were determined by X-ray diffraction analysis. The reported results shed light on how to control the emergents of the multicomponent reaction mixture that forms koneramines. Reactivity studies of the intermediates pave the way for a new type of koneramine complexes that are new dipicolylamines where the two pyridine moieties of the resulting koneramine are not the same.

Synthetic [NiFe] models with a fluxional CO ligand.

A [NiFe] complex [(dppe)Ni(pdt)FeCp*(CO)]+ was isolated and characterized as two isomers [1(CO)]+ and [1'(CO)]+. Heating the solution of [1(CO)]+ allowed it to convert into [1'(CO)]+. The one-electron oxidation of [1'(CO)]+ to [1'(CO)]2+ induced fluxional CO movement providing [1(CO)]2+. Recovery of [1(CO)]+ was realized by the one-electron reduction of [1(CO)]2+.

An immuno-chromatographic lateral flow assay (LFA) for rapid on-the-farm detection of classical swine fever virus (CSFV).

Classical swine fever (CSF) is a highly contagious and potentially fatal disease of domestic pigs. Classical swine fever is routinely diagnosed by clinical signs, serology, detection of CSF virus (CSFV) nucleic acid by PCR and virus isolation. Most of the current CSF diagnostic methods are expensive and have an extended turnaround time. In the majority of the CSF endemic countries, lack of easy access to diagnostic facilities is a major problem for swine producers trying to obtain early diagnosis and often results in the entire herd being infected. The acute form of CSF can show non-specific signs of illness, leaving CSF often undiagnosed. Hence there is an urgent need for a rapid and reliable pen side diagnostic assay for the better detection and control of this economically important disease of swine. We developed an immuno-chromatographic lateral flow assay (LFA) for on the farm detection of CSFV. A CSFV isolate [CSFV/AP/TRP2/2009 (TS2)] of genotype 1.1 was used for the production of monoclonal antibodies (mAbs) for the LFA's development. The virus detection level of the LFA device was 36.8 TCID50/ml of CSFV. The sensitivity and specificity of LFA in comparison with PCR were 80.36% and 87.10%, respectively. The positive and negative predictive values of the LFA device were 91.84% and 87.10%, respectively. In conclusion, the CSFV-LFA is a reliable and convenient resource for preliminary on the farm detection of classic swine fever.

Multicomponent One-pot Reactions Towards the Synthesis of Stereoisomers of Dipicolylamine Complexes.

Reported are multi-component one-pot syntheses of chiral complexes [M(L(R) OR')Cl2 ] or [M(L(R) SR')Cl2 ] from the mixture of an N-substituted ethylenediamine, pyridine-2-carboxaldehyde, a primary alcohol or thiol and MCl2 utilizing in-situ formed cyclized Schiff bases where a C-O bond, two stereocenters, and three C-N bonds are formed (M=Zn, Cu, Ni, Cd; R=Et, Ph; R'=Me, Et, nPr, nBu). Tridentate ligands L(R) OR' and L(R) SR' comprise two chiral centers and a hemiaminal ether or hemiaminal thioether moiety on the dipicolylamine skeleton. Syn-[Zn(L(Ph) OMe)Cl2 ] precipitates out readily from the reaction mixture as a major product whereas anti-[Zn(L(Ph) OMe)Cl2 ] stays in solution as minor product. Both syn-[Zn(L(Ph) OMe)Cl2 ] and anti-[Zn(L(Ph) OMe)Cl2 ] were characterized using NMR spectroscopy and mass spectrometry. Solid-state structures revealed that syn-[Zn(L(Ph) OMe)Cl2 ] adopted a square pyramidal geometry while anti-[Zn(L(Ph) OMe)Cl2 ] possesses a trigonal bipyramidal geometry around the Zn centers. The scope of this method was shown to be wide by varying the components of the dynamic coordination assembly, and the structures of the complexes isolated were confirmed by NMR spectroscopy, mass spectrometry, and X-ray crystallography. Syn complexes were isolated as major products with Zn(II) and Cu(II) , and anti complexes were found to be major products with Ni(II) and Cd(II) . Hemiaminals and hemiaminal ethers are known to be unstable and are seldom observed as part of cyclic organic compounds or as coordinated ligands assembled around metals. It is now shown, with the support of experimental results, that linear hemiaminal ethers or thioethers can be assembled without the assistance of Lewis acidic metals in the multi-component assembly, and a possible pathway of the formation of hemiaminal ethers has been proposed.

N-Substituted Derivatives of the Azadithiolate Cofactor from the [FeFe] Hydrogenases: Stability and Complexation.

Experiments are described that probe the stability of N-substituted derivatives of the azadithiolate cofactor recently confirmed in the [FeFe] hydrogenases (Berggren, G., et al. Nature 2013, 499, 66). Acid-catalyzed hydrolysis of bis(thioester) BnN(CH2SAc)2 gives [BnNCH2SCH2]2 rather than azadithiol BnN(CH2SH)2. Treatment of BnN(CH2SAc)2 with NaO(t)Bu generates BnN(CH2SNa)2, which was trapped with NiCl2(diphos) (diphos = 1,2-C2H4(PR2)2; R = Ph (dppe) and Cy (dcpe)) to give fully characterized complexes Ni[(SCH2)2NBn](diphos). The related N-aryl derivative Ni[(SCH2)2NC6H4Cl](diphos) was prepared analogously from 4-ClC6H4N(CH2SAc)2, NaO(t)Bu, and NiCl2(dppe). Crystallographic analysis confirmed that these rare nonbridging [adt(R)](2-) complexes feature distorted square planar Ni centers. The analogue Pd[(SCH2)2NBn](dppe) was also prepared. (31)P NMR analysis indicates that Ni[(SCH2)2NBn](dppe) has basicity comparable to typical amines. As shown by cyclic voltammetry, the couple [M[(SCH2)2NBn](dppe)](+/0) is reversible near -2.0 V versus Fc(+/0). The wave shifts to -1.78 V upon N-protonation. In the presence of CF3CO2H, Ni[(SCH2)2NBn](dppe) catalyzes hydrogen evolution at rate of 22 s(-1) in the acid-independent regime, at room temperature in CH2Cl2 solution. In contrast to the instability of RN(CH2SH)2 (R = alkyl, aryl), the dithiol of tosylamide TsN(CH2SH)2 proved sufficiently stable to allow full characterization. This dithiol reacts with Fe3(CO)12 and, in the presence of base, NiCl2(dppe) to give Fe2[(SCH2)2NTs](CO)6 and Ni[(SCH2)2NTs](dppe), respectively.

Transcriptome profiling reveals higher vertebrate orthologous of intra-cytoplasmic pattern recognition receptors in grey bamboo shark.

From an immunologist perspective, sharks are an important group of jawed cartilaginous fishes and survey of the public database revealed a great gap in availability of large-scale sequence data for the group of Chondrichthyans the elasmobranchs. In an attempt to bridge this deficit we generated the transcriptome from the spleen and kidney tissues (a total of 1,606,172 transcripts) of the shark, Chiloscyllium griseum using the Illumina HiSeq2000 platform. With a cut off of > = 300 bp and an expression value of >1RPKM we used 43,385 transcripts for BLASTX analysis which revealed 17,548 transcripts matching to the NCBI nr database with an E-value of < = 10(-5) and similarity score of 40%. The longest transcript was 16,974 bases with matched to HECT domain containing E3 ubiqutin protein ligase. MEGAN4 annotation pipeline revealed immune and signalling pathways including cell adhesion molecules, cytokine-cytokine receptor interaction, T-cell receptor signalling pathway and chemokine signaling pathway to be highly expressed in spleen, while different metabolism pathways such as amino acid metabolism, carbohydrate metabolism, lipid metabolism and xenobiotic biodegradation were highly expressed in kidney. Few of the candidate genes were selected to analyze their expression levels in various tissues by real-time PCR and also localization of a receptor by in-situ PCR to validate the prediction. We also predicted the domains structures of some of the identified pattern recognition receptors, their phylogenetic relationship with lower and higher vertebrates and the complete downstream signaling mediators of classical dsRNA signaling pathway. The generated transcriptome will be a valuable resource to further genetic and genomic research in elasmobranchs.

Rapid detection of the Marek's disease viral genome in chicken feathers by loop-mediated isothermal amplification.

A loop-mediated isothermal amplification (LAMP) method for the rapid detection of serotype 1 Marek's disease virus (MDV) was developed. The method used a set of three pairs of primers to amplify the MEQ gene for detecting serotype 1 MDV. The MDV LAMP method did not cross-react with serotype 2 and serotype 3, nor did the LAMP primers have binding sites for the common avian DNA viruses (reticuloendotheliosis virus, chicken anemia virus, subgroup J of the avian leukosis virus). Additionally, the assay could detect up to 10 copies of the MEQ gene in the MD viral genome, and it had 10 times higher sensitivity than the traditional PCR methods. The LAMP master mix was stable for 90 days at -20°C. Furthermore, the efficiency of LAMP for detection of serotype 1 MDV in clinical samples was comparable to those of PCR and viral isolation. The LAMP procedure is simple and does not rely on any special equipment. The detection of serotype 1 MDV by LAMP will be useful for detecting and controlling oncogenic Marek's disease.

A New Route to Azadithiolato Complexes.

The reaction of [(MeC(5)H(4))(2)Ti(SH)(2)] with cyclic imines with the formula (CH(2)NR)(3) gives 2-aza-1,3-dithiolato chelate complexes [(MeC(5)H(4))(2)Ti{(SCH(2))(2)NR}] (1, R = Ph; 2, R = Me; 3, R = CH(2)Ph). These compounds demonstrate that azadithiolate ligands can exist on mononuclear metal centers. The complexes were characterized by (1)H NMR spectroscopy, ESI-mass spectrometry, and X-ray crystallography. Variable-temperature (1)H NMR studies reveal that the dithiolate ligands undergo ring inversion like other dithiatitanacyclohexanes. Treatment of [(MeC(5)H(4))(2)Ti{(SCH(2))(2)NPh}] (1) with [Fe(benzylideneacetone)(CO)(3)] afforded [Fe(2){(SCH(2))(2)NPh}(CO)(6)] in good yield.

Electrocatalytic CO2 conversion to oxalate by a copper complex.

Global warming concern has dramatically increased interest in using CO2 as a feedstock for preparation of value-added compounds, thereby helping to reduce its atmospheric concentration. Here, we describe a dinuclear copper(I) complex that is oxidized in air by CO2 rather than O2; the product is a tetranuclear copper(II) complex containing two bridging CO2-derived oxalate groups. Treatment of the copper(II) oxalate complex in acetonitrile with a soluble lithium salt results in quantitative precipitation of lithium oxalate. The copper(II) complex can then be nearly quantitatively electrochemically reduced at a relatively accessible potential, regenerating the initial dinuclear copper(I) compound. Preliminary results demonstrate six turnovers (producing 12 equivalents of oxalate) during 7 hours of catalysis at an applied potential of -0.03 volts versus the normal hydrogen electrode.

Reduction of protons assisted by a hexanuclear nickel thiolate metallacrown: protonation and electrocatalytic dihydrogen evolution.

The hexanuclear metallacrown [Ni6L12] (L is mu-S-CH2-CH2-S-C6H4-Cl) has been demonstrated to functionally resemble the [NiFe] hydrogenases. Protonation of the [Ni6L12] cluster was studied employing 1H NMR spectroscopy by the sequential additions of dichloroacetic acid or p-toluenesulfonic acid monohydrate into solutions of [Ni6L12] in CD2Cl2 and DMF-d7, respectively; protonation takes place on the thioether sulfurs available in the metallacrown. Electrochemical properties of both the parent and protonated [Ni6L12] species have been studied using cyclic voltammetry. Protonated [Ni6L12] shows an interesting electrocatalytic property as it catalyzes the reduction of protons to molecular hydrogen in the presence of protic acids, such as dichloroacetic acid and chloroacetic acid at -1.5 and -1.6 V vs. Ag/AgCl in DMF, respectively. A catalytic cycle has been proposed based on the observations from the NMR spectroscopic and electrochemical studies of the metallacrown. The behavior of this electrocatalyst was further studied by its immobilization on the surface of a pyrolytic graphite electrode; reduction of a dichloroacetic acid solution in acetonitrile on the surface of the modified electrode occurs at 220 mV more positive potential compared to the unmodified electrode.

A molecular cage of nickel(II) and copper(I): a [{Ni(L)2}2(CuI)6] cluster resembling the active site of nickel-containing enzymes.

A new mononuclear low-spin nickel(II) dithiolato complex, [NiL(2)] (1), reacts with copper iodide to form the hetero-octanuclear cluster [{Ni(L)(2)}(2)(CuI)(6)] (2) with four trigonal-planar CuI(2)S and two tetrahedral CuI(2)S(2) sites; anagostic interactions between the nickel(II) ions and aromatic protons have been demonstrated by variable-temperature NMR studies to pertain in solution.

Hexanuclear [Ni6L12] metallacrown framework consisting of NiS4 square-planar and NiS5 square-pyramidal building blocks.

The hexanuclear [Ni(6)L(12)] (2) wheel-type cluster adopts an unusual structural motif whereby four NiS(4) square-planar and two NiS(5) square-pyramidal units are conjoined by edge sharing; the NiS(5) units resemble the Ni centre of the inactive state in the [NiFe] hydrogenase.