Synthesis of Bio-Base Fluorescence Carbon Dots for Selective Detection of Tartrazine and Sunset Yellow in Food Samples.

A green, economical and simple method for the preparation of water-soluble, high-fluorescent carbon quantum dots (CQDs) has been developed via hydrothermal process using pomelo peels as carbon source. The synthesized CQDs were characterized by transmission electron microscopy (TEM), X-ray diffraction(XRD), Fourier transform infrared spectroscopy (FTIR), UV - vis absorption spectra and fluorescence spectrophotometer. The results reveal that the as-prepared C-dots were spherical shape with an average diameter of 2.64 nm and emit bright blue photoluminescence (PL) with a quantum yield of approximately 3.63%. The surface of the C-dots was rich in hydroxyl groups and presented various merits including excellent photostability, low toxicity, and satisfactory solubility. Additionally, we found that two widely used synthetic food colorants, tartrazine and sunset yellow, could result in a strong fluorescence quenching of the C-dots, The possible mechanisms are caused by different ratios of inner filter and static quenching effects. According to this property, This study attempts to establish an analytical method for the determination of tartrazine and sunset yellow using carbon quantum dots as fluorescent probe. A linear relationship was found in the range of 0-100 µM tartrazine and sunset yellow with the detection limit(3σ/k) of 0.65 nM and 1.7 nM. The relative standard deviation (RSD) was 3.5% (tartrazine) and 3.0% (sunset yellow).This observation was further successfully applied for the determination of tartrazine and sunset yellow in food samples collected from local markets, and the recovery rates of the two ranges from 79% to 117.8 and 81 -103.5%, respectively. suggesting its great potential toward food routine analysis.

A highly sensitive C3-symmetric Schiff-base fluorescent probe for Cd2+.

A new C3-symmetric Schiff-base fluorescent probe (L) based on 8-hydroxy-2-methylquinoline has been developed. As expected, the probe L can display high fluorescent selectivity for Cd(2+) over Zn(2+) and most other common ions in neutral ethanol aqueous medium. Moreover, the mechanism of the L-Cd(2+) complex has been confirmed by X-ray crystallography and density functional theory calculation results. More importantly, L could be used to image Cd(2+) within living cells.

Green one-step synthesis of N-doped carbon quantum dots for fluorescent detection of lemon yellow in soft drinks.

A new fluorescent sensor for the determination of lemon yellow was developed based on nitrogen-doped carbon quantum dots (N-CQDs), which were prepared via a hydrothermal method with dried pomelo peel and L-tyrosine. The N-CQDs exhibited the blue fluorescence with a quantum yield of 28 %. The sensing principle of N-CQDs was quenched by lemon yellow via static quenching. The potential interfering substances showed no influence on the detection of lemon yellow. The limit of detection was 0.023 mg/L and lower than that of national standard. Furthermore, the synthesized N-CQDs have been successfully applied to the measurement of lemon yellow in real samples. Hence, the N-CQDs would be a promising sensor in food analysis.

catena-Poly[[silver(I)-µ-4,4'-bipyridine-κ(2)N:N'] 4-[2-(4-carb-oxy-phen-yl)-1,1,1,3,3,3-hexa-fluoro-propan-2-yl]benzoate].

Assembly of the flexible dicarb-oxy-lic ligand 4-[2-(4-carboxyphenyl)-1,1,1,3,3,3-hexafluoropropan-2-yl]benzoate and 4,4'-bipyridine as co-ligand with Ag(I) ions resulted in the formation of the polymeric title compound, {[Ag(C(10)H(8)N(2))](C(17)H(9)F(6)O(4))}(n), in which the metal atoms are bridged by the 4,4'-bipyridine ligands, generating cationic chains extending along [010]. The dihedral angles between the benzene rings in the anion and the pyridine rings in the cation are 72.42 (9) and 9.36 (10)°, respectively. The mol-ecular conformation of the anion is stabilized by intra-molecular C-H⋯F hydrogen bonds. In the crystal, the anions inter-act with the cationic chains via C-H⋯O hydrogen bonds, forming layers parallel to (001), in which weak π-π stacking inter-actions [centroid-centroid distances = 3.975 (3)-4.047 (3) Å] involving the pyridine rings of adjacent 4,4'-bipyridine ligands are present. The planes are further assembled into a three-dimensional network by O-H⋯O hydrogen bonds.

4-Amino-3,5-bis-(2-pyrid-yl)-4H-1,2,4-triazole-benzene-1,2,3-tricarboxylic acid-water (1/1/2).

Cocrystallization of 4-amino-3,5-bis-(2-pyrid-yl)-1,2,4-triazole (2-bpt) with hemimellitic acid (benzene-1,2,3-tricarboxylic acid) dihydrate (H(3)HMA·2H(2)O) produces the supra-molecular title compound, C(12)H(10)N(6)·C(9)H(6)O(6)·2H(2)O. Inter-molecular N-H⋯N hydrogen bonds are observed between the terminal pyridyl and amino groups of the 2-bpt molecule and the dihedral angles between the central ring and the pendant pyridine rings are 3.4 (7) and 13.8 (7)°. In the structure, homosynthons of graph set R(2) (2)(8) are observed to form centrosymmetric H(3)HMA dimers, which are extended into a two-dimensional supra-molecular layer via inter-molecular O-H⋯N and C-H⋯O hydrogen bonds and π-π stacking inter-actions [centroid-centroid distance = 3.541 (3) Å]. In addition, inter-layer uncoordinated water mol-ecules connect the layers through O-H⋯O hydrogen bonds, generating a three-dimensional network.

Direction of unusual mixed-ligand metal-organic frameworks: a new type of 3-D polythreading involving 1-D and 2-D structural motifs and a 2-fold interpenetrating porous network.

The reaction of Cu(II) or Cd(II) acetate with mixed ligands terephthalic (tp) and 3,5-bis(4-pyridyl)-4-amino-1,2,4-triazole (bpt) under the same conditions affords two unusual metal-organic frameworks, in which represents a new type of polythreaded supramolecular architecture consisting of distinct 1-D and 2-D coordination polymers within one crystal, however, has an interpenetrating porous network with two similar laterally interlocking 2-D (4,4) layers.

A dual functional probe for "turn-on" fluorescence response of Pb(2+) and colorimetric detection of Cu(2+) based on a rhodamine derivative in aqueous media.

A dual functional probe L based on rhodamine was devised and synthesized. Probe L can sense Pb(2+) and Cu(2+) in aqueous solution through two approaches: a significant fluorescence enhancement caused by Pb(2+) and a visible color change from colorless to orchid induced by Cu(2+). Competitive experiments showed that probe L had high fluorescence sensitivity for Pb(2+) and excellent colorimetric selectivity for Cu(2+) over many environmentally relevant ions. The mechanisms of L for sensing Pb(2+) and Cu(2+) have been well demonstrated by ESI-MS, (1)H NMR titration, IR, the crystal structure of L-Pb(2+) and density functional theory calculation of L-Cu(2+). In addition, fluorescence image detection of Pb(2+) in living cells displayed an enhanced fluorescence effect.

New fluorescent sensor for Cu(2+) and S(2-) in 100% aqueous solution based on displacement approach.

An On-Off-On type fluorescent sensor (HL) has been developed, which exhibited high selectivity and sensitivity for Cu(2+) over other common ions in 100% aqueous solution. Once HL combined with Cu(2+), blue fluorescence was almost completely quenched and the L-Cu ensemble was formed. Moreover, the ensemble showed high specificity for S(2-) based on the displacement approach, and no interferences were observed in the presence of other anions. Such fluorescence modulation behavior simulates the performance of an IMPLICATION logic gate. In addition, the fluorescent sensor was successfully applied to fluorescent cellular imaging implying potential applications in physiological and environmental systems.

Blood pressure control rate and associated risk factors in hospitals of different grades in Chongqing, China.

OBJECTIVE: The present article aimed to provide accurate estimate of the control rate of hypertension and the influencing factors in hospitals of different grades in Chongqing. METHODS: In this survey, hypertensive outpatients were recruited from 5 tertiary hospitals, 6 secondary hospitals and 5 primary hospitals in 9 districts of Chongqing from November 2011 to May 2012. Outpatients were investigated by clinical interview with BP measurement and questionnaire. Univariate analyses and logistic regression analysis was used to assess the effect of variables on control of hypertension. RESULT: A total of 2742 hypertensives were studied, of which 820 were from primary hospitals, 901 from secondary hospitals and 1021 from tertiary hospitals. The total control rate for hypertensive outpatients in Chongqing was 46.0%. The control rate of the primary,secondary and tertiary hospitals were 38.7%、46.7%、51.1%. Multinomial Logistic Regression showed that the control rate was positively correlated with mastery of knowledge of hypertension, normal BMI;whereas it was positively correlated with peasantry,the dissatisfactory with doctor's manner and the distrust to doctor. CONCLUSION: Blood pressure control rate of hypertensive outpatients in Chongqing was low.High BMI, peasantry, lack of knowledge of hypertension, doctors' manners, distrust to doctor were the key reasons for low BP control rate.

A new fluorescent probe for Al(3+) based on rhodamine 6G and its application to bioimaging.

A water-soluble rhodamine-based derivative (L) has been rationally designed for selective recognition of Al(3+) in aqueous medium with good sensitivity. The addition of Al(3+) to the aqueous solution of L induces a remarkable fluorescence enhancement along with obvious color change detected by the naked eye, due to the ring-opening mechanism of the rhodamine spirolactam, which has been proved by single crystal diffraction analyses directly. The recognizing behavior has been investigated both experimentally and computationally. Furthermore, the fluorescent probe can also be used as a bioimaging reagent for detection of Al(3+) in living cells.

Two new isomerous fluorescent chemosensors for Al(3+) based on photoinduced electron transfer.

Two new isomerous PET fluorescent chemosensors (L and L') for Al(3+) have been designed, synthesized and characterized. The two chemosensors exhibited fluorescence enhancement upon binding Al(3+) in CH3CN by PET inhibition processes from both the sulfur and the nitrogen donors to anthracene. The job's plot, Benesi-Hildebrand plot and (1)H NMR titration experiments indicate that both chemosensors form a 1:1 complex with Al(3+). The binding constants were calculated to be (1.432±0.186)×10(5) and (1.427±0.970)×10(5), respectively. Furthermore, the lowest detection limit for Al(3+) in CH3CN was determined to be 4.8×10(-7)M and 2.2×10(-7)M, respectively.

[The correlation study of HBV serological index in neonate's venus, cord blood and mother's venus blood].

OBJECTIVE: In this study, we discussed the consistency and correlation of HBV serological indexes between neonates' venous blood and cord blood whose mothers had chronical HBV infection, as well as the correlation of thoses indexes with the mothers'. METHOD: Chronically HBV infected mothers who were postive of both HBsAg and HBeAg and also had a HBV DNA virus load above 10(5) copies/ ml and their infants were enrolled. The mothers' venous blood were collected before delivery. The neonates' cord blood were collected at birth after removal of contaminants and disinfected with alcohol on the cord's surface, and the venous blood were collected before hepatitis B virus immune globin(HBIG) and hepatitis B vaccine were given. The levels of HBsAg, anti-HBs, HBeAg and anti-HBeAg were tested with Abbott microparticle chemiluminescence method (Abbott Laboratories, Abbott Architac i2000). HBV DNA quantification were tested by COBAS TagMan real-time PCR Assay. RESULTS: 383 mothers and their infants were enrolled. The positive rates of HBsAg in cord blood and venous blood were 61.2% and 63.9%. The positive rates of HBeAg level in cord blood and venous blood were 83.2% and 83.5%. The positive rates of HBV DNA level in cord blood and venous blood were 56.0% and 59.4%. The state of HBsAg, HBeAg and HBV DNA in cord blood and venous blood were consistency, and significant correlation was observed in their levels with correlation coefficients of 0.766, 0.857, and 0.692, respectively (P < 0.000). Significant correlation of the HBeAg levels were observed between mothers' venous blood and neonates' venous blood, as well as neonates' cord blood with correlation coefficients of 0.362 and 0.352 (P < 0.000). However, there was no significant correlation of HBsAg levels between them (r = 0.023, P = 0.785; r = 0.04, P = 0.604). CONCLUSIONS: The HBV serological index of neonate's cord blood could reflect the HBV serological indexes in venous blood because of the good correlation and consistency between them.

Molecular tectonics of mixed-ligand metal-organic frameworks: positional isomeric effect, metal-directed assembly, and structural diversification.

A series of nine mixed-ligand metal-organic frameworks (MOFs) have been prepared by the combination of a bent dipyridyl linker 4-amino-3,5-bis(4-pyridyl)-1,2,4-triazole (bpt) and three benzenedicarboxylate isomers (pa = phthalate, ip = isophthalate, and tp = terephthalate), respectively, with different metal ions such as CoII, NiII, CuII, ZnII, and CdII. The framework structures of these neutral polymeric complexes have been determined by the X-ray single-crystal diffraction technique. Structural analysis reveals that the benzenedicarboxylate isomers display versatile coordination modes to manage the metal ions to form 1-D chain or ribbon arrays, which are further extended via the exo-bidentate bpt connectors to give rise to a variety of coordination networks, such as a simple (4,4) layer, 2-D double layer with decorated (4,4) topology, 2-D layer with decorated (3,6) topology, 2-D bilayer with 82.10 topology (2-fold interpenetration), 3-D polythreaded architecture (1-D + 2-D), and 2-fold interpenetrating porous lattice of (4,4) layers. The accessorial secondary interactions such as hydrogen bonding and/or aromatic stacking are also helpful for the extension and stabilization of the final supramolecular aggregates. This work evidently indicates that the isomeric effect of the anionic benzenedicarboxylate is significant in the construction of these network structures, which are also well regulated by the metal centers. The ZnII and CdII MOFs exhibit strong solid-state luminescence emissions at room temperature, which originate differently from intraligand transition or ligand-to-metal charge transfer. Thermal stability of these crystalline materials has been explored by thermogravimetric analysis of mass loss. The 3-D host frameworks of MOFs 8 and 9 show similar porous cavities, and their desorption/adsorption behaviors of guest solvents have also been investigated.

Controllable assembly of metal-directed coordination polymers under diverse conditions: a case study of the M(II)-H3tma/Bpt mixed-ligand system.

A series of new metal-organic polymeric complexes, [[Co(bpt)(Htma)(H2O)3].2.25H2O]n (1), [Co(bpt)(Htma)(H2O)]n (2), [Ni(bpt)(Htma)(H2O)]n (3), [Zn(bpt)2(H2tma)2].6H2O (4), [[Cd(bpt)(Htma)(H2O)].(C2H5OH)(H2O)1.5]n (5), and [[Cd(bpt)(Htma)(H2O)2].5.5H2O]n (6), was prepared from solution reactions of 4-amino-3,5-bis(4-pyridyl)-1,2,4-triazole (bpt) and trimesic acid (H3tma) with different metal salts under diverse conditions. All these compounds were structurally determined by X-ray single-crystal diffraction, and the bulk new materials were further identified by X-ray powder diffraction. Complexes 1 and 6 show 1-D zigzag or linear Htma-bridged polymeric chains, with the terminal bpt ligands as pendants, which are extended to 2-D hydrogen-bonded arrays with 4.8(2) or (6,3) network topology. Coordination polymers 2 and 3, in which the 2-D corrugated metal-organic frameworks make the interdigitated 3-D packing, are isostructural. Complex 4 has a mononuclear structure, and its subunits are hydrogen-bonded to each other to give a 2-D grid-like net. For complex 5, the Cd(II) centers are linked by bpt/Htma ligands to form a 2-D (4,4) coordination layer, and these layers are interdigitated in pairs. Notably, secondary noncovalent forces, such as hydrogen bonds, play an important role in extending and stabilizing these structural topologies. Interestingly, distinct products are obtained for Co(II) (1 and 2) and Cd(II) (5 and 6) under ambient or hydrothermal conditions; however, for Ni(II) and Zn(II), single products, 3 and 4, are generated. The thermal stabilities of 1-6 were studied by thermogravimetric analysis of mass loss. The desorption/adsorption properties of the porous material 5 are also discussed. Solid-state luminescent spectra of the Zn(II) and Cd(II) complexes, 4-6, indicate intense fluorescent emissions at ca. 380 nm.