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To extend the industrial polymer species classification and improve its efficiency. Laser-induced breakdown spectroscopy (LIBS) combined with unsupervised learning algorithms of self-organizing maps (SOM) and K-means was employed to differentiate industrial polymers in the open air. Only the intensities of non-metallic lines, including two molecular band lines (C-N(0,0) 388.3 nm and C2(0,0) 516.5 nm) and four atomic emission lines (C I 247.9 nm, H I 656.3 nm, N I 746.9 nm and O I 777.3 nm) were used. Firstly, the SOM neural network with adjusting spectral weightings (ASW) was applied to separate 20 kinds of polymers preliminarily. The results were obtained in the output space which indicated that 18 kinds of polymers have been separated except for polycarbonate (PC) and polystyrene (PS). Afterwards, the K-means clustering algorithm was utilized to separate PC and PS. The accuracy of the industrial polymers classification for 20 kinds of polymers was 99.2%. It demonstrated that the feasibility of clustering of industrial polymers using LIBS.

We evaluated the effects of Klotho on pulmonary vascular remodeling and cell proliferation and apoptosis in rat models with PM2.5-induced pulmonary arterial hypertension (PAH) via the Wnt signaling pathway. After establishing rat models of PM2.5-induced PAH, these Sprague-Dawley male rats were randomized into control and model groups. Cells extracted from the model rats were sub-categorized into different groups. Activation of Wnt/β-catenin signaling transcription factor was detected by a TOPFlash/FOPFlash assay. A serial of experiment was conducted to identify the mechanism of Klotho on PHA via the Wnt signaling pathway. VEGF levels and PaCO2 content were higher in the model group, while PaO2, NO2- /NO3- content and Klotho level was lower compared to the control group. In comparison to the control group, the model group had decreased Klotho and Bax levels, and elevated Wnt-1, β-catenin, bcl-2, survivin, and PCNA expression, VEGF, IL-6, TNF-α, TNF-β1, and bFGF levels, as well as the percentage of pulmonary artery ring contraction. The Klotho vector, DKK-1 and DKK-1 + Klotho vector groups exhibited reduced cell proliferation, luciferase activity, and the expression of Wnt-1, β-catenin, bcl-2, survivin, and PCNA, as well as shortened S phase compared with the blank and NC groups. Compared with the Klotho vector and DKK-1 groups, the DKK-1 + Klotho vector groups had reduced cell proliferation, luciferase activity, and the expression of Wnt-1, β-catenin, bcl-2, survivin, and PCNA, as well as a shortened S phase. Conclusively, Klotho inhibits pulmonary vascular remodeling by inactivation of Wnt signaling pathway.

The method of spatially selective laser-stimulated absorption (SS-LSA) was proposed to reduce self-absorption in laser-induced breakdown spectroscopy (LIBS). Through scanning intensity maps of analytes, it was discovered that elemental distribution was inhomogeneous in the formed plasma. Taking copper (Cu) and chromium (Cr) elements in steel as examples, the distribution of Cu and Cr has its own characteristics. By focusing the laser beam on the optimal locations of the plasma with an optical parametric oscillator (OPO) wavelength-tunable laser, the linear determination coefficient (R2 factor) for Cu and Cr elements can reach 0.993 and 0.999, respectively. For Cu determination, compared with LIBS and LSA-LIBS, the root-mean-square error of cross-validation (RMSECV) of SS-LSA-LIBS decreased by 81 and 52%, respectively. The analytical accuracy of the quantitative analysis was much higher than those of conventional LIBS and LSA-LIBS, which indicates that the proposed method can effectively reduce self-absorption and improve LIBS analytical performance.

The quantitative method of iodine monoxide radical (IO) using incoherent broadband cavity enhanced absorption spectroscopy (IBBCEAS) in the 435–465 nm band is described in this paper. In order to obtain the concentration of IO accurately, the parameters such as the mirror reflectivity, effective cavity length and sample loss of the IBBCEAS system are evaluated. Using the difference of Rayleigh scattering between nitrogen and helium, the reflectivity curve of the high-reflection mirror is obtained. The reflectivity R of the mirror at 436.1 nm of the IO absorption peak is about 0.99982, and the effective absorption optical path reaches 3.83 km under vacuum condition. According to the absorption of O4, the effective cavity length of the modified system is 60.7 cm. The Allan deviation is used to evaluate the performance of the system, and the standard deviation is used to analyze the detection sensitivity of the system. When the time resolution is 60 s, the detection sensitivity (2σ) of the system for IO and NO2 are 1.9 pptv and 20 pptv (part per trillion by volume), respectively. The iodine dissolved in potassium iodide (KI) solution is taken out by the bubbling method and react with ozone after photolysis to produce a stable concentration of IO sample gas. The IO loss in the sampling tube is calibrated, and the results show that the sampling tube has no significant effect on the IO loss. The IBBCEAS system is used to determine the linearity of IO, and the correlation coefficient R2 between the measured concentration of IO and the proportioned concentration in a concentration range from 39 to 530 pptv is 0.99. The IO produced by the reaction of iodine released from kelp with ozone is measured.

A portable laser-induced breakdown spectroscopy (LIBS) system based on a fiber laser was developed and employed to quantitatively analyze manganese (Mn), vanadium (V), and silicon (Si) elements in steels. After background removal, the coefficients of determination (R2 factors) of the calibration curves for Mn, V, and Si elements reached 0.997, 0.991 and 0.992, respectively, obvious improvements compared to those of the original spectra. The leave-one-out cross-validation (LOOCV) method was used to test the system. The root-mean-square error of cross-validation (RMSECV) for Mn (0.072–2.06 wt%), V (0.009–0.821 wt%), and Si (0.099–1.85 wt%) elements were 0.037, 0.041 and 0.079 wt%, respectively. The average relative errors (AREs) for Mn elements reached 7.6%. These results are comparable with those of the conventional LIBS which refers to utilizing the traditional flash-lamp-pumped laser as a laser source. However, compared to conventional LIBS, a fiber laser LIBS (FL-LIBS) is more compact, robust, and cost effective. The FL-LIBS, coupling a compact fiber laser and spectrometer, is a convenient approach to providing a portable solution for real-time and in situ detection in industry, especially in harsh environments.

In this work, we demonstrate the advantage of bifacial silicon heterojunction (SHJ) solar module in energy harvest capabilities through an on-going terrestrial study. Two PV stations built with our bifacial 60-cell standard SHJ modules yield 15% and 18.9% more in Chengdu compared to an n-type monocrystalline silicon reference PV station, mainly due to enhanced insolation through the rear side. In addition, performances of SHJ modules under various circumstances are also investigated. It is shown that bifacial SHJ modules can be widely incorporated with non-conventional applications without significant yield loss.

To develop a hydrogen source for underwater applications, a composite of sodium borohydride and super absorbent polymer (SAP) is prepared by ball milling sodium borohydride powder with SAP powder, and by dehydrating an alkaline borohydride gel. When sodium polyacrylate (NaPAA) is used as the SAP, the resulting composite exhibits a high rate of borohydride hydrolysis for hydrogen generation. A mechanism of hydrogen evolution from the NaBH 4 –NaPAA composite is suggested based on structure analysis by X-ray diffraction and scanning electron microscopy. The effects of water and NiCl 2 content in the precursor solution on the hydrogen evolution behavior are investigated and discussed.

The title complex Eu(III)(TTA)3(phen) (where TTA = thenoyltrifluoroacetone monoanion; phen = 1,10-phenanthroline) has been synthesized in mixed solvents of acetone and ethanol (1:1 volume ratio) and its crystal structure has been determined by X-ray diffraction. The complex crystals are triclinic, space group P 1 (# 2) with cell dimensions of a = 1.32.41 (2) nm, b = 1.5278(4) nm, c = 0.9755(3) nm, α = 92.49 (2)°, β = 102.57(2)°, γ = 91.62(2)°, V = 1.9268(8) nm3, Z = 2, μ (Mo Ka)= 18.77 cm−1, Dx=1.720 g/cm3. The coordination geometry of Eu atom is a distorted square antiprism, and the encapsulated structure that can meet the structural requirement of the typical europium luminescent sensor. The fluorescence spectrum suggests that the complex is a strong photoluminescent material.

The title polymeric complex [Cu(C4H2O4)(C10H8N2)]n·2nH2O was prepared and its crystal structure was determined by X-ray diffraction methods. The crystal belongs to space group P21/c with cell dimensions of a = 1.0104(1), b = 1.9952(2), c = 0.7357(2) nm, β= 98.38(2)° and Z = 4. The complex forms zig-zag chains along crystallographic axis c via Cu—O (carboxyl) bond in the apical direction. Each repeated unit consists of a square pyramidal Cu(II) centre with one maleate dianion and one 2,2′-bipyridine forming a basal plane. Adjacent chains link to each other by H-bonding between carboxyl groups and crystalline water. The distance of 0.3482 nm between parallel bipyridine rings shows a π-π stacking interaction. The title complex was also characterized by IR, UV and ESR spectra.

Crystals of the chiral malic acid hydrate (C4H6O3 · H2O) were unexpectedly obtained from an ethanol/water solution containing racemic D, L-malic acid and L-asparagine. The crystal belongs to orthorhombic space group P212121 with cell dimensions of a = 0.5576(1), b = 0.9818(2), c = 1.1793(2) nm, V = 0.6455(2) nm3, Z = 4, μ(Mo Ka =0.152 mm−1, F(000) = 320, Dc= 1.565 g·cm−3, R = 0.051, wR = 0.136 for 657 observed reflections [I < 2σ(I)]. The significant difference in bond distances for carboxyl groups suggests that the crystal consist of malate anion and protonized crystalline water. This is a report for direct separation of racemic mixture, i.e., without the formation of a molecular complex of raceme with a chiral separating reagent.

The self-absorption effect seriously affects the accuracy of determination in laser-induced breakdown spectroscopy (LIBS). In this work, we proposed to reduce multielemental self-absorption within a wide spectral range (200-900 nm) by using microwave-assisted excitation in LIBS (MAE-LIBS). Self-absorption reduction of sodium (Na), potassium (K), aluminum (Al), silicon (Si), and calcium (Ca) in potassium feldspar using MAE-LIBS was investigated. The mechanisms of self-absorption reduction in MAE-LIBS were also investigated. The results show that the serious self-absorption of spectral lines (Na and K) was reduced. The full widths at half maximum (FWHMs) of Na I 589.0 nm, Na I 589.6 nm, K I 766.5 nm, and K I 769.9 nm in potassium feldspar were reduced by 43%, 43%, 53%, and 47%, respectively. MAE-LIBS also has a little FWHM reduction for spectral lines with weak self-absorption. The results demonstrate that MAE-LIBS can simultaneously reduce multielemental self-absorption.

The supramolecular framework [Cu2(TU)4 · (TAA)4] n (TU = thiourea; TAA = 2-(2-imino-4-oxo-5-thiazolidinylidene)acetic anion) has been synthesized by reaction of CuCl2 · 2H2O with meso-2,3-dibromosuccinic acid and thiourea. The one-dimensional supramolecular structure of the title complex is constructed through bridge-linkage of the S atoms on the thioureas between adjacent Cu(II) atoms, forming an infinite chain with lots of positive charges. Around the infinite chain, there are four groups of negatively charged hydrogen-bond tubes constructed by four TAA anions. The hydrogen-bond and ionic interactions between adjacent metal-organic polymeric chains and hydrogen-bond tubes form the three-dimensional supramolecular structure of the complex. Supramolecular selectivity from isomers of 2-(2-imino-4-oxo-5-thiazolidinylidene)acetic anion (TAA) has been studied by quantum calculation.

HONO is a source of OH via photolysis. An incoherent broadband cavity enhanced absorption spectrometer on mobile platforms has been developed for simultaneous measuring the spatial distribution of HONO and NO2

The title complex, Ni(C8H8N2S2)(C4H4O5)(H2O) · 3H2O, was synthesized and its crystal structure determined by X-ray diffraction methods. Two crystallographically independent complex molecules are present in the asymmetric unit. They have similar octahedral coordination geometries, formed by a bidentate dimethylbithiazole (dMbt), a tridentate oxydiacetate dianion (ODA) and a coordinated water molecule. The tridentate ODA ligand displays an unusual facial configuration. A partially overlapped arrangement of nearly parallel dMbt ligands of neighbouring molecules is observed in the crystal, the shortest centroid distance of 3.555(3) A between thiazole rings suggesting the existence of aromatic π–π stacking.

A novel empirical force field CRACK was developed for n -alkane that allowed for covalent bond breaking and forming, and can be used to investigate the pyrolysis of alkanes by classical molecular dynamics simulation (MD). The shape of CRACK potential-energy curve was for the pyrolysis reactions, with a deep harmonic well, an activation energy barrier and another shallow Lennard-Jones well. To validate CRACK force field, classical MD was performed to simulate the pyrolysis reactions of n -octane and n -decane. The defined pyrolytic temperature T p could be adjusted by the displacement constant de in accord with the pyrolysis energy barrier presented by CRACK. T p of n -octane was found higher than that of n -decane at the same de is consistent with the pyrolysis fundamentals. The results of time histories of pyrolysis reactions and of distribution of pyrolysis product revealed that CRACK force field certainly reflected the recombination between different molecules. The microscopic pyrolysis kinetics was discussed and the pyrolysis reaction was found to reach its equilibrium within the simulation time 100 ps. The evaluated rate constant in apparent first order increased with the elevated temperature or the decreased value of de. The distribution of the pyrolysis products was analyzed in details and was compared with the experimental data. The results demonstrate that CRACK force field can be applied to predict the product distribution at least qualitatively by MD.

The title polymeric complex [Ni(C7H6N2)3(C4H2O4)] n has been prepared and its crystal structure determined by single-crystal X-ray diffraction methods. The complex is orthorhombic, space group P212...

The complex Mn(im)2(4-mbo)2·H2O (im = imidazole, 4-mbo = 4-methylbenzoate) has been prepared and its structure determined by X-ray diffraction methods. Mn(II) assumes a distorted octahedral coordination geometry formed by imidazole, water molecules and 4-mbo anions. Two 4-mbo ligands bind to Mn(II) with different coordination modes, one as a monodentate and the other as a chelate. Comparison of measured Mn–O bond distances and corresponding bond angles with those of other Mn(II) complexes incorporating monodentate carboxylate ligands suggests more electrostatic interaction between the Mn and carboxyl O atoms of the title complex. The interplanar distance between parallel imidazole rings [3.470 (13) A] is indicative of aromatic π–π stacking, whereas the distance between the parallel benzene rings of neighboring 4-mbo anions [3.761(13) A] is a normal van der Waals contact. Extensive hydrogen bonding occurs between the complex molecules.

The crystal structure of the complex tris(benzimidazole)iminodiacetato(2-)cadmium(II) dihydrate, (BZIM)3(IDA)Cd·2H2O, was determined by single-crystal X-ray methods. The Cd(II) ion assumes distorted octahedral coordination geometry formed by three benzimidazole molecules and an iminodiacetate dianion. The dianion chelates Cd(II) as a terdentate in the facial configuration. Weak intermolecular C–H···π interactions exist between neighboring benzimidazole rings. The thermal decomposition of the title complex has been studied. IR assignments based on the molecular structure have been made.

Crystals of the title compound, [(C6H6N4S2)(C4H5NO4)(H2O)Ni]·H2O, consist of the Ni(II) complex and lattice water. The Ni(II) complex adopts a distorted octahedral coordination geometry formed by an iminodiacetate anion (IDA), a diaminobithiazole (DABT) and a coordinated water molecule. A twisted configuration of DABT is the distinguishing feature in the complex, the dihedral angle between thiazole rings of DABT being 20.04(8)°. An aromatic stacking interaction occurs between thiazole rings from neighboring complex molecules, and is considered as the reason for the twisted configuration. The tridentate IDA dianion chelates to a Ni(II) atom in afacialconfiguration. A hydrogen bond network holds the complex molecules together to form a supramolecular structure.

The crystal structure of the title complex was determined by single-crystal X-ray diffraction methods. The unit cell contains two independent molecules, A and B. B is a mononuclear Cu(II) complex with square-planar coordination geometry formed by two benzimidazole molecules and two hydroxylbenzoate anions. A is a dimer of B, formed by bridging hydroxybenzoate, and copper assumes square-pyramidal geometry. Aromatic π–π stacking is observed between parallel benzimidazole rings of neighboring A molecules. IR spectra of the compound are assigned in line with the crystal structure.

The molecular structure of tetra(imidazole)copper(II) terephthalate was determined by single-crystal X-ray diffraction methods. The complex is triclinic, space group , with a = 8.0299(6), b = 8.4180(7), c = 8.8992(4) A, α = 77.122(3), β = 68.898(3), γ = 76.116(2)°, V = 538.59(7) A3. The Cu(II) atom is located on an inversion center and assumes tetragonally elongated octahedral coordination geometry, with an axial Cu–O(carboxyl) bond distance of 2.682(2) A. The terephthalate dianion is located on another inversion center and bridges neighboring Cu(II) atoms to form polymeric chains. IR spectra of the complex are consistent with the crystal structure.

The title compound has been prepared and its crystal structure determined by X-ray diffraction methods. The complex salt consists of Mn(II) complex cations, benzoate anions and lattice water molecules. Mn(II) assumes a distorted octahedral geometry defined by two 1,10-phenanthroline (phen) ligands, a Cl− ion and a water molecule. A comparison of bond distances and bond angles suggests electrostatic interaction between Mn(II) and coordinated N atoms. The nitrobenzoate anion does not coordinate to the Mn atom but links with the complex cation via O−H···O hydrogen bonds. Aromatic stacking occurs between phen rings and between phen and benzoate.

The title complex has been prepared and its crystal structure determined by X-ray diffraction methods. The complex crystallizes in the monoclinic space group P21/c. Cu(II) assumes a square pyramidal coordination geometry, formed by two isonicotinate anions, a bipyridine ligand and a coordinated water molecule. Each isonicotinate bridges two Cu atoms through pyridine-N and carboxyl-O atoms, respectively, to form zigzag polymeric chains. Between the polymeric chains, aromatic stacking and hydrogen bonding are observed.

The title copper(II) complex [Cu2(C4H2O4)2(phen)2]⋅4H2O (phen = 1,10-phenanthroline) was prepared and its crystal structure was determined by X-ray diffraction method. The crystal belongs to space group C2/c with cell of a = 18.136(5), b = 12.505(5), and c = 14.617(5) A, β = 103.440(5)∘ and Z = 4. The Cu(II) atom assumes a square pyramidal coordination geometry with a longer Cu–O3 coordination distance [2.308(3) A] in the apical direction. The carboxyl O3 atoms from two maleate dianion bridges two Cu(II) atoms to form the binuclear complex with a shorter Cu⋅sCu separation of 3.349(1) A. The separations of 3.39(1) and 3.41(1) A between parallel phen rings indicate the existence of aromatic stacking.

The title compound crystallizes in the triclinic space group with a = 7.194(3), b = 9.790(5), c = 12.492(1) A, α = 82.407(16), β = 86.664(15), γ = 89.882(15)°. The Mn(II) complex assumes distorted octahedral coordination geometry, formed by diaminobithiazole (DABT), an oxydiacetate dianion (ODA) and a water molecule. The tridentate ODA ion chelates to the Mn(II) atom in a meridional configuration. Each carboxyl group coordinates to the Mn(II) atom as a monodentate. Uncoordinated carboxyl oxygen atoms are involved in a hydrogen-bonding network. DABT chelates to the Mn(II) atom with a coplanar configuration. Coordinated water is hydrogen bonded to carboxyl groups of ODA of a neighboring complex to form supramolecular chains. A π–π stacking interaction involving thiazole rings occurs between adjacent supramolecular chains. A difference of 180 cm−1 between asymmetric and symmetric stretching vibrations of the carboxyl group corresponds to the extensive hydrogen-bonding network involving the carboxyl group.

Mitochondrial disorders are a group of clinically and genetically heterogeneous diseases. Common recurrent mitochondrial DNA (mtDNA) point mutations account for the molecular defects of a small proportion of patients. In order to identify mtDNA mutations, comprehensive mutational analysis of the entire mitochondrial genome is necessary. We developed the temporal temperature gradient gel electrophoresis (TTGE) method to screen for mutations in mtDNA. The entire mitochondrial genome was amplified using 32 pairs of overlapping primers followed by TTGE analysis of the DNA fragments. TTGE method was first validated on 200 DNA fragments containing known mutations or polymorphisms. On TTGE, homoplasmic nucleotide substitutions show a single band shift and heteroplasmic mutations show multiple banding patterns. The known mutations or polymorphisms were correctly identified. TTGE was then used to screen for unknown mutations in the mitochondrial genome. DNA banding patterns, deviated from wild-type, suggestive of either homoplasmic or heteroplasmic mutations, were followed by direct DNA sequencing to identify the mutations. Numerous mutations and polymorphisms were detected. The results demonstrated that TTGE detects and distinguishes heteroplasmic mutations from homoplasmic polymorphisms. It also detects heteroplasmic changes in the background of a homoplasmic polymorphism. Overall, TTGE was proven to be a simple, rapid, sensitive, and effective mutation detection method.

The title compound, [HgI2(CH4N2S)2]·2C11H6N2O, is comprised of the Hg(II)–thiourea complex and free 4,5-diazafluoren-9-one (DAFONE). The complex assumes a distorted tetrahedral geometry at mercury formed by two thiourea molecules and two I− ions, the S–Hg–S angle [103.7°] being significantly smaller than S–Hg–I angles (115.2 and 114.3°). The complex and DAFONE molecules link to each other via hydrogen bonding to form a supramolecular structure. Significant π–π stacking is observed between neighboring DAFONE molecules.

The title complex, (C7H6N2)3(C4H5NO4)Co·2H2O, has been prepared and its crystal structure determined by single-crystal X-ray diffraction methods. The cobalt atom is octahedrally coordinated by three benzimidazole molecules and an iminodiacetate anion. The anion coordinates facially as a tridentate. Extensive intermolecular hydrogen bonding and C−H· · ·π interactions occur in the crystal. Thermal decomposition of the complex has been studied by thermogravimetry and differential scanning calorimetry. The IR spectral assignments were based on the molecular structure.

Crystals of the title complex with diaminobithiazole (DABT) were obtained by a solution diffusion method. X-ray diffraction analysis shows the complex to be monoclinic, space group P21/c with cell ...

The title complex was prepared by reaction of succinatomanganese(II) with imidazole in water-ethanol. The complex crystallizes in orthorhombic space group Pna 2 1 with a = 7.9990(15), b = 14.8690(15), c = 11.028(2) A. The metal assumes a distorted octahedral coordination. In the crystal, each succinate dianion bridges three Mn(II) atoms to form a polymer with a layered structure.

The title complex has been prepared and its crystal structure determined by X-ray diffraction methods. The Mn (II) complex is seven coordinate with two benzimidazole (bimid)ligands in axial positions and two succinate and one bimid ligands in the equatorial plane. The succinate bridges Mn (II) atoms to form polymeric chains, linked by intermolecular H-bonding. Free bimid molecules occur in the crystal structure; they link Mn (II) complexes with H-bonds involving N atoms. Aromatic stacking between bimid rings is observed, resulting in a gauche confirmation of succinate in the structure. The IR spectrum is assigned based on the crystal structure. The difference of 139cm-1 between symmetric and asymmetric stretching vibrations of carboxyl groups is in line with seven coordination at the Mn (II) atom.

4-Aminobenzoic acid (PABA) has been successfully separated from a mixture containing 2-aminobenzoic acid and (2R,3R)-tartaric acid. X-ray structure analysis confirms the separating result. The molecular complex formed by PABA and tartaric acid in 1:1 molar ratio crystallizes in the orthorhombic space group P212121 with cell dimensions of a = 7.329(1) A, b = 12.095(2) A, c = 15.231(3) A, V = 1350.1(4) A3, Z = 4. The crystal structure comprises protonated PABA, monoanion of tartaric acid, and crystalline water. The extensive H-bonding network exists in the crystal structure. H bonding between tartaric acid and both terminal groups on para position of PABA is considered as a possible reason for the successful separation.

A polymeric complex of Cd(II) and Ag(I) bridged by thiocyanate and ethylenediamine, [Cd(en)1.5Ag(SCN)3], has been prepared and its structure determined by X-ray diffraction methods. The complex crystallizes in space group P21/n with a =7.456(1), b =9.915(2), c =19.822(2)A, β =98.94(1)°. The Cd(II) atom is octahedrally coordinated by three SCN- anions and two en molecules, while the Ag(I) atom is tetrahedraly coordinated by four SCN- anions. Both SCN- anions and en molecules act as bridging ligands and link Ag(I) and Cd(II) atoms to form a three-dimensional polymeric structure. The distance between Ag(I) and the atom S of a 1,1,3-µ3-SCN- anion is much longer than that between Ag(I) and the atom S of a 1,3-µ-SCN- anion. The short Ag-Ag distance of 3.133 A and small Ag-S-Ag angle of 70.92° strongly suggests the existence of an Ag-Ag bonding interaction in the complex.

The title complex [Mn(bipy)2Cl2]·0.5bipy·2.5H2O, where bipy = 2,2'-bipyridine, has been prepared and its crystal structure has been determined by X-ray diffraction methods. The complex crystallizes in the triclinic space group P-1, with a = 8.814(2), b = 11.335(2), c = 13.347(3) A, α = 76.85(2), β = 89.55(2), γ = 86.52(2)°. Two chloride and two bipy ligands cis-coordinate to a Mn(II) atom with a distorted octahedral geometry. The crystal consists of Mn(II) complex, free bipy and crystalline water. The complex crystalline water link to each other by H-bonding to form supra-molecular chains, and free bipy molecules locate between parallel chains with a van der Waals contact distance of 3.58(1) A. A π-π interaction is also observed between adjacent bipy rings. The chelating bipy and free bipy showed different IR absorptions.

The title complex [Cu2(C4H2O4)2(bipy)2(H2O)3] · 3H2O (bipy = 2,2'-bipyridine) was prepared and its crystal structure determined by X-ray diffraction methods. Both Cu(II) atoms of the binuclear complex assume square pyramidal coordination. The fumarate groups display different coordination modes. One fumarate group bridges two Cu(II) ions to form a binuclear complex while another fumarate group terminally coordinates to a Cu(II) atom with one carboxyl group free from coordination. The terminally coordinated fumarate showed unusual disorder, which may be due to an intermolecular H-bonding interaction. Close stacking of bipy rings is observed as verified by the distance of 3.46 A between parallel ring planes. IR spectra were assigned based on the molecular structure.

As dicarboxylate complexes of transition metal possess potentially useful electronic and magnetic properties, [Mehrotra and Bohra (1983). Metal Carboxylates. Academic Press, London], much interest in their synthesis and structure has been apparent recently [Kaneko and Tsuchida (1981). J. Polymer Sci . , Macromolecular Reviews, 16, 397; Holton, Lappert, Pearce and Yarrow (1983). Chem. Reviews, 83, 135]. A series of metal complexes bridged by dicarboxylates has been synthesized in our laboratory and crystal structures show versatile coordination modes for the carboxyl group [Cheng, Liu, Xu and Xu (1999). J. Coord. Chem., 48 , 495; Nie, Liu, Luo and Xu (2001). J. Coord. Chem., 53, 365]. As a part of this investigation, we have synthesized a binuclear fumarate complex of Cu(II). X-ray analysis shows considerable coordination distortion resulting from close stacking interaction of aromatic phen rings.

The daily changes in the behavior of xanthophyll cycle and antioxidant systems in flag leaves of superhigh-yield hybrid rice were investigated in relation to various developing stages. Dark-adapted Fv/Fm decreased with the increasing incident light intensity on leaf surface in the morning and then minimized at midday; Deepoxidation State showed an opposed daily pattern to Fv/Fm at different developing stage. As compared with increased deepoxidation state maximum value, the relative content of xanthophyll cycle pigments remained almost constant during development. The daily changes in activities of superoxide dismutase, ascorbate-peroxidase and glutathione reductase and the content of ascorbate and glutathione displayed a similar pattern, where they increased from 8:00 and reached maximum at midday, however, a lower daily fluctuation of superoxide dismutase activity was observed in senescent leaves. The enhanced contribution of xanthophyll cycle and Mehler-ascorbate peroxidase reaction to photoprotection in old leaves could be partially due to the altered leaf posture. In conclusion, daily changes of xanthophyll cycle and antioxidant systems in leaves of rice at various developing stages were dependent on leaf age, leaf angle and intensity of solar irridiance.

The title complex, [Mn(C3H4N2)4(H2O)2]·(C8H4O4), was prepared by reaction of terephthalato (diaqua)manganese (II) with imidazole in ethanol/water solution. The complex crystallizes in space group C2/c with cell parameters a = 22.494(5), b = 7.741(2), c = 16.287(3)A, β = 120.94(3)°, Z = 4. The complex consists of complex Mn(II) cations and uncoordinated terephthalate anions; the latter link cations through an H-bonding network. Thermal analyses and IR spectra are discussed in terms of the formation of the complex.

A novel Mn(II) complex bridged by 1,3-benzenedicarboxylate (BDC) has been synthesized by the diffusion method. The complex crystallizes in space group P21/c with a = 8.345(2), b = 10.427(1), c = 18.756(2) A, β = 100.19(1)°. Each BDC bridges three Mn(II) atoms through two carboxyl groups with different coordination modes to form a complex polymeric chain. The coordination geometry around the Mn(II) atom is seriously distorted from the normal octahedron. Large deviations of the donor atoms out of the coordination planes and unexpected bond angles around Mn(II) and donor O atoms suggest the existence of an electrostatic interaction between Mn(II) and donor atoms in the complex. Close stacking of aromatic rings is observed in the complex, the distance between the neighboring phen planes being 3.2085 A.

The title complex [Mn(C4H4O4)(phen)(H2O)3] · 2H2O has been prepared and its crystal structure determined by X-ray diffraction methods. The Mn(II) atom has octahedron coordination formed by four oxygen and two nitrogen atoms. The coordination mode of the succinate dianion in the complex is remarkably different from those reported previously. One carboxyl group of the succinate dianion coordinates to the Mn(II) atom as a monodentate and the other carboxyl group is free. The crystal structure consists of the complex and crystalline water molecules. All the oxygen atoms in the structure take part in an H-bonding network and assemble to form a hydrophilic layer, while phenanthroline ligands between neighboring hydrophilic layers to form a hydrophobic layer. Tight stacking interactions of phenanthroline rings are observed in the hydrophobic layer as evidenced by the short distance (3.312 A) between neighbouring parallel ring planes.

A new Ni(II) complex with an amino acid Schiff base has been prepared by reaction of the Li(I) salt of the tetraglycol aldehyde bis(methionine) Schiff base and Ni(NO 3 )·6H 2 O in methanol solution. Characterization by elemental analysis, magnetic susceptibility and infrared spectroscopy suggests a binuclear structure. The Ni(II) complex shows catalytic polymerization activity.

The title compound including a stable nitroxide radical was synthesized by a reaction of N,N′-diisopropylcarbondiimide (DIC) with 2,2,5,5-tetramethyl-1-oxo-3-pyrroline-3-carboxylic acid (TPCO) in an EtOAc solution under nitrogen atmosphere. From 1:1 EtOAc/hexane the compound crystallizes in triclinic space group P $$\overline 1$$ with a = 11.078(2), b = 11.970(2), c = 15.746(3) A, α = 105.41(3), β = 103.47(3), γ = 106.52(3)°, and Z = 4. In an asymmetric unit two molecules assemble with each other in similar bond distances and angles but show crystallographically independent conformation. A normal single C–N bond is observed in the title compound, other than the partial double C=N bond shown in the parent urea. A longer N–O distance of 1.26 A implies the existence of a single electron π bond between N and O atoms, which stabilizes the radical molecule.

The title complex has been obtained from the solution of 4-methylphenol and piperazine, and the crystal structure has been determined by X-ray diffraction analysis. The complex crystallizes in space group P -1, each piperazine molecule linking two 4-methylphenol molecules via H-bonding between the amine N atoms and the phenol hydroxyl group. 1 H NMR spectra indicate that the complex formed with the aid of H-bonding exists also in the solution. The proton peaks assigned to the hydroxyl and amine groups in pure 4-methylphenol and piperazine merge into one in the title complex, which implies that the H-bond between the hydroxyl O and the amine N atoms is involved in a fast proton exchange process. The ESI-MS spectrum of the solution of the title complex also provides evidence for the existence of the 2:1 complex in the solution.

The title complex, Cu2(C10H2O8)(C3H4O2)6(H2O)4 · 4H2O, consists of polymeric copper(II) complex anions and discrete copper(II) complex cations. Benzenetetracarboxyl anions bridge copper(II) atoms c...

From an ethanol/water solution containing (1R,3S)-camphoramic acid and a racemic mixture of mandelic acid, the title complex crystallizes in the space group P212121 with a = 8.015(2), b = 11.041(2), c = 21.781(4) A. Both molecular complexes, the (1R,3S)-camphoramic acid (S)-mandelic acid complex and the (1R,3S)-camphoramic acid (R)-mandelic acid complex, randomly distribute in a disordered crystal structure with an approximate molar ratio of 3:1, thus a 3:1 separation of the mandelic acid enantiomers was achieved. Molecules of (S)-mandelic and (R)-mandelic acid form very similar intermolecular interactions with adjacent camphoramic acid and water molecules in the structure. This results in the formation of a cocrystal containing two diastereomers. The crystal structure consists of camphoramic acid layers and mandelic acid layers. An extensive H-bonding network occurs within and between the layers.

A novel (2+2) macrocyclic Schiff base lanthanide(III) complex [La(H4L)(NO3)3]·(4,4′-bipy)·2H2O has been synthesized by template condensation of 1,3-diamino-2-hydroxypropane and 2,6-diformyl-4-chlorophenol. The compound crystallizes in the orthorhombic space group Pnma with a = 16.400(3), b = 12.985(3), c = 19.118(4) A, and Z = 4. In the macrocycle, La3+ was coordinated by two imino nitrogen atoms, two phenolic oxygen atoms, one pedant alcoholic oxygen atom, and six nitrate oxygen atoms. It is interesting that the neutral lanthanide macrocyle forms a saddlelike supramolecule with 4,4′-bipyridine.

The complex [Cu2(μ-cis-oxpn)(phen)(NO3)2], where oxpn = N,N′ -bis(3-aminopropyl) oxamidato and phen = 1,10-phenanthroline, has been synthesized and its crystal structure determined by X-ray methods. The structure consists of binuclear copper (II) molecules in which the Cu(II) atoms are bridged by oxamidato group in the cis conformation, the Cu—Cu distance being 5.205(10) A. The coordination geometry around Cu (II) atoms is square pyramidal; the apex is occupied by a more weakly bonded O atom from a nitrate group. Electron delocalization is observed in the bridging oxamide moiety. The co-planarity of bridge ligand and basal plane around Cu (II) atoms may benefit spin super-exchange between two Cu (II) atoms. IR spectra of the binuclear complex are discussed.

The binuclear copper(II) complex [Cu2(dien)2(NCS)2](ClO4)2, where dien = diethylenetriamine, has been synthesized and characterized by analysis, infrared (IR) and electron paramagnetic resonance (EPR) spectra. A centrosymmetric axial‐equatorial 1,3-μ-NCS bridged binuclear copper(II) complex has been identified by X-ray diffraction, in which each copper(II) is five-coordinated with an elongated square pyramidal geometry with four nitrogen atoms on its basal plane and one sulfur atom at the apical position. Frozen solution EPR spectra at 77 K indicate that the interaction between the two copper centers is weak and the bridge is retained in solution.

The complex Cu(hfac)2(DMF)2 (where hfac = the anion of hexafluoropentanedione and DMF = dimethylformamide) has been prepared and its crystal structure has been determined by X-ray diffraction methods. The complex molecule locates around an inversion centre in the crystal state. Two DMF ligands coordinate to the Cu(II) atom in the axial direction while two hfac ligands chelate to the Cu(II) atom in the equatorial plane. The remarkable feature of this structure is that the difference of 0.032(3) A in coordination bond distances between the axial direction and the equatorial plane shows a very small Jahn-Teller distortion around the Cu(II) atom.

The crystal structure of [Ni(trpn)(NCS)2] (trpn = tris(3-aminopropyl)amine) has been determined, in which the nickel(II) complex is octahedral. The complex forms a three-dimensional network through weak intermolecular hydrogen bonds SNCS … H-Namine and S … S contacts.