Isolation and Reactivity of Stannylenoids Stabilized by Amido/Imino Ligands.

The reaction of the lithium aryl(silyl)amide Dipp(i Pr3 Si)NLi (Dipp=2,6-i Pr2 C6 H3 ) with one equivalent of SnCl2 in THF gave a novel stannylenoid Dipp(i Pr3 Si)NSnCl⋅LiCl(THF)2 . Heating the solution of amidostannylenoid in toluene to 80 °C resulted in dimeric amido(chloro)stannylene [Dipp(i Pr3 Si)NSnCl]2 , which can be converted to bis(amido)stannylene Sn[N(Dipp)(i Pr3 Si)]2 and amido(imino)stannylene Sn[N(Dipp)(i Pr3 Si)][IPrN] (IPrN=bis(2,6-diisopropylphenyl)imidazolin-2-imino). Treatment of bis(imino)stannylenoid [IPrN]2 Sn(Cl)Li with N2 O resulted in the dimeric complex [IPrNSn(Cl)OLi]2 . All compounds were characterized by NMR, elementary analysis, and X-ray structural determination.

Isolation and Reactivity of Tetrylene-Tetrylone-Iron Complexes Supported by Bis(N-Heterocyclic Imine) Ligands.

The germanium iron carbonyl complex 3 was prepared by the reaction of dimeric chloro(imino)germylene [IPrNGeCl]2 (IPrN=bis(2,6-diisopropylphenyl)imidazolin-2-iminato) with one equivalent of Collman's reagent (Na2 Fe(CO)4 ) at room temperature. Similarly, the reaction of chloro(imino)stannylene [IPrNSnCl]2 with Na2 Fe(CO)4 (1 equiv) resulted in the Fe(CO)4 -bridged bis(stannylene) complex 4. We observed reversible formation of bis(tetrylene) and tetrylene-tetrylone character in complexes 3 vs. 5 and 4 vs. 6, which was supported by DFT calculations. Moreover, the Li/Sn/Fe trimetallic complex 12 has been isolated from the reaction of [IPrNSnCl]2 with cyclopentadienyl iron dicarbonyl anion. The computational analysis further rationalizes the reduction pathway from these chlorotetrylenes to the corresponding complexes.

An Isolable Three-Coordinate Germanone and Its Reactivity.

A rare three-coordinate germanone [IPrN]2 Ge=O (IPrN=bis(2,6-diisopropylphenyl)imidazolin-2-imino) was successfully isolated. The germanone has a rather high thermal stability in arene solvent, and no detectable change was observed at 80 °C for at least one week. However, high thermal stability of [IPrN]2 Ge=O does not prevent its reactivity toward small molecules. Structural analysis and initial reactivity studies revealed the highly polarized nature of the terminal Ge=O bond. Besides, the addition of phenylacetylene, as well as O-atom transfer with 2,6-dimethylphenyl isocyanide make it a mimic of nucleophilic transition-metal oxides. Mechanism for O-atom transfer reaction was investigated via DFT calculations, which revealed that the reaction proceeds via a [2+2] cycloaddition intermediate.

[Bioinformation analysis of chorismate synthase in Baphicacantus cusia and other 78 species of plants].

Chorismate synthase(CS, EC:4.2.3.5) catalyses 5-enolpyruvy-shikimate-3-phosphate to form chorismate, which is the essential enzyme for chorismate biosynthesis in organisms. The amino acid sequences of CS from 79 species of higher plants were reported in GenBank at present. 125 amino acid sequences of CS from Baphicacanthus cusia and other 78 species of plants were predicted and analyzed by using various bioinformatics software, including the composition of amino acid sequences, signal peptide, leader peptide, hydrophobic/hydrophilic, transmembrane structure, coiled-coil domain, protein secondary structure, tertiary structure and functional domains. The phylogenetic tree of CS protein family was constructed and divided into eight groups by phylogenetic analysis. The homology comparison indicated that B. cusia shared a high homology with several plants such as Sesamum indicum, Nicotiana tabacum, Solanum tuberosum and so on. The open reading frame(ORF) of all samples is about 1 300 bp, the molecular weight is about 50 kDa, the isoelectric point(pI) is 5.0-8.0 which illustrated that CS protein is slightly basic. The ORF of CS we cloned in B. cusia is 1 326 bp, the amino acid residues are 442, the molecular weight is 47 kDa and pI is 8.11. The CS in B.cusia showed obvious hydrophobicity area and hydrophilicity area, no signal peptide, and may exists transmembrane structure areas. The main secondary structures of CS protein are random coil and Alpha helix, also contain three main structural domains which are an active structural domain, a PLN02754 conserved domain and a FMN binding site. The acquired information in this study would provide certain scientific basis for further study on structure-activity relationship and structure modification of CS in plants in the future.

A Novel Coumarin-Based Fluorescent Probe for the Detection of Hydrazine Both in Aqueous Solution and Vapor State.

A novel coumarin-based fluorescent probe CF was synthesized for the detection of hydrazine both in aqueous solution and vapor state with high sensitivity and selectivity. Upon addition of hydrazine, the solution of probe CF in MeCN-H2O (3/7, v/v, buffered CH3COOH/CH3COONa) at pH 5.0 exhibited a remarkable change in emission color from pale green to light blue, which could be recognized with naked eyes. Applied in weak acid condition, probe CF could detect hydrazine selectively with large amount of unknown environments according to the competing tests. Besides, with the limit of detection 8.32 ppb (2.6 × 10(-7) M), probe CF could well meet the request (10 ppb) of the U.S. Environmental Protection Agency (EPA).

A water-soluble pH fluorescence probe based on quaternary ammonium salt for bioanalytical applications.

A novel fluorescence probe Rhodamine-Ethanediamine-Iodomethane (REI) was successfully prepared to serve as an efficient sensing platform for H(+) with fully reversibility mainly between the pH 4.2 and 7.2 in simple buffer solution. The introduction of quaternary ammonium salt with positive charge can not only manage to increase the solubility and sensitivity of probe REI, but also avoid the "alkalizing effect" due to charge-induced effect compared to the reference probe Rhodamine-Ethanediamine (RE). In particular, probe REI was well used for monitoring the weak acid pH fluctuations in lysosome of the live HeLa cells due to its excellent biological properties, including low cytotoxicity, high selectivity, good sensitivity and membrane permeability.

A dansyl based fluorescence chemosensor for Hg(2+) and its application in the complicated environment samples.

We have developed a novel fluorescent chemosensor (DAM) based on dansyl and morpholine units for the detection of mercury ion with excellent selectivity and sensitivity. In the presence of Hg(2+) in a mixture solution of HEPES buffer (pH 7.5, 20 mM) and MeCN (2/8, v/v) at room temperature, the fluorescence of DAM was almost completely quenched from green to colorless with fast response time. Moreover, DAM also showed its excellent anti-interference capability even in the presence of large amount of interfering ions. It is worth noting that DAM could be used to detect Hg(2+) specifically in the Yellow River samples, which significantly implied the potential applications of DAM in the complicated environment samples.

A unique dansyl-based chromogenic chemosensor for rapid and ultrasensitive hydrazine detection.

We developed a new dansyl phthalimide-based fluorescent chemosensor for hydrazine detection. Upon a Gabriel type-based hydrazinolysis of dansyl phthalimide (DPI) in the presence of hydrazine in a mixture of HEPES buffer (pH 7.0, 20 mM) and DMSO (1/9, v/v) at room temperature, the chemosensor produces fluorescent dansyl-NH2 with the maximum emission wavelength changed from 475 nm to 512 nm along with a color change from yellow to colorless, allowing colorimetric detection of hydrazine by the naked eye. DPI can selectively detect hydrazine over other environmentally abundant ions. Moreover, DPI coated with silica gel TLC plates could act as a visual and fluorimetric probe for hydrazine vapor at a partial pressure of 5.5 × 10-3 mm Hg over other potentially interfering volatile analytes, including hydrogen peroxide, ethylenediamine, urea, ammonium hydroxide and methylamine. DPI can also be used for the detection of hydrazine in water samples and HeLa cells without appreciable interference from other biologically abundant analytes. The limit of detection is 6.01 ppb (1.88 × 10-7 M), which is well below the accepted limit (10 ppb) for hydrazine set by the U.S. Environmental Protection Agency (EPA).