Silica gel luminophors containing 1, 10-phenanthroline-tris(M-Methylbenzoate) europium (or terbium) com- plexes were prepared bysol-gel method. The thermal decomposition, excitation and emissionspectra for the gel pho...Silica gel luminophors containing 1, 10-phenanthroline-tris(M-Methylbenzoate) europium (or terbium) com- plexes were prepared bysol-gel method. The thermal decomposition, excitation and emissionspectra for the gel phos- phors were measured and compared with thatof solid complex powders. The thermal stability of the complexes wasen- hanced in SiO_2 host matrix and the luminescence intensityremained unchanged.展开更多
Two new cobalt(Ⅱ)complexes[Co2(2,2?-bipy)2(dpa)2(H2O)5]·4H2O(1)and Co(2,2?-bipy)3(SO4)]·7.5H2O(2)have been synthesized with diaphonic acid(H2dpa)and 2,2?-bipyridine(2,2?-bipy)as ligands.In 1,two neighboring...Two new cobalt(Ⅱ)complexes[Co2(2,2?-bipy)2(dpa)2(H2O)5]·4H2O(1)and Co(2,2?-bipy)3(SO4)]·7.5H2O(2)have been synthesized with diaphonic acid(H2dpa)and 2,2?-bipyridine(2,2?-bipy)as ligands.In 1,two neighboring cobalt(Ⅱ)ions are linked together by one bridging diaphonic acid group,forming an asymmetric dinuclear structure.1 crystallizes in triclinic,space group P1 with a=9.825(6),b=13.007(8),c=19.586(1)A,α=80.773(1)o,β=77.065(1)o,γ=85.902(1)o,Mr=431.4,V=2406.5(3)A^3,Dc=1.48 g/cm^3,Z=2,μ(Mo Kα)=0.767 mm-1,F(000)=1112,the final R=0.0379 and wR=0.0862.The central cobalt(Ⅱ)ions in 1 and 2 are coordinated with six atoms,forming distorted octahedral coordination geometry.The fluorescence and thermal stability properties of 1 and 2 are also reported.展开更多
Ternary complexes of europium and terbium with benzoic acid and 1, 10 phenanthroline [RE(BA) 3phen] (BA=benzoate phen=1,10 phenanthroline) were introduced into a silica matrix by sol gel method. The thermal stabil...Ternary complexes of europium and terbium with benzoic acid and 1, 10 phenanthroline [RE(BA) 3phen] (BA=benzoate phen=1,10 phenanthroline) were introduced into a silica matrix by sol gel method. The thermal stability and luminescence behavior of the complexes in silica gels were studied in comparison with the corresponding solid state complexes by thermal decomposition, excitation and emission spectra. The thermal stability of the complexes is enhanced in silica gel matrix and the luminescence remaines unchanged.展开更多
A series of isostructural d/f molecular compounds Zn(H2L)Ln(NO3)3·CH3OH(Ln = Dy(1), Tb(2) and Sm(3)) were synthesized by the introduction of a designed multifunctional ligand N,N?,N??,N???-tetra...A series of isostructural d/f molecular compounds Zn(H2L)Ln(NO3)3·CH3OH(Ln = Dy(1), Tb(2) and Sm(3)) were synthesized by the introduction of a designed multifunctional ligand N,N?,N??,N???-tetra(2-hydroxy-3-methoxy-5-methylbenzyl)-1,4,7,10-tetraazacyclododecan(H4L = C(44)H(60)N4O8). In the isostructural molecules, each crystallographically independent Zn2+ and Ln3+ centers are connected by two phenolic oxygen atoms. For the six-coordinate Zn-(2+) ion, the coordination geometry can be viewed as a regular bicapped square pyramid. While for the ten-coordinate Ln-(3+) ion, if each O,O?-chelated nitrate ligand is seen as a single coordination site, the coordination geometry can be viewed as a distorted pentagonal bipyramid. The fluorescent spectra show that compounds 2 and 3 exhibited characteristic sharp emissions of Tb-(3+) and Sm-(3+), respectively, while compound 1 was found to be a single-component white-light-emitting complex in the solid state. Thermal stabilities of the three compounds were investigated by using thermal gravimetric analysis. In addition, the thermal decomposition of compound 1 was confirmed by temperature-dependent powder X-ray diffraction technique.展开更多
The stability constants of the mononuclear complexes of BDBPH-Zn(II), Cd(II) and Mn (II) were determined by the potentiometric equilibrium measurements, and species distributions were also discussed. The metal ions do...The stability constants of the mononuclear complexes of BDBPH-Zn(II), Cd(II) and Mn (II) were determined by the potentiometric equilibrium measurements, and species distributions were also discussed. The metal ions do not combine with the ligand until the first two protons of the ligand have almost been completely neutralized. The main species were mononuclear complexes with the diprotonated ligand, MH,L. The three metal ions also form mono- and noprotonated (fully deprotonated) complexes, MHL, ML. The relative order of stabilities of the mononuclear complexes, ML, is Zn(II) > Cd(II) > Mn(II). The ligand has strong tendency to form mononuclear complexes with Zn(II), Cd(II) and Mn(II), and it can also form dinuclear complexes at high pH.展开更多
The reactions LnCl3 (s) + (3/2)Al2Cl6, (g) = LnAl3Cl12 (g) for Ln = La to Lu were studied by quenching experiments in roughly the same temperature and pressure ranges (588-851 K and 0.01-0.22 MPa). Stability constant...The reactions LnCl3 (s) + (3/2)Al2Cl6, (g) = LnAl3Cl12 (g) for Ln = La to Lu were studied by quenching experiments in roughly the same temperature and pressure ranges (588-851 K and 0.01-0.22 MPa). Stability constants Kθ of lanthanide complexes LnAl3Cl12 were calculated from the measurements. The values of Ig Kθ change linearly with the ionpotential (Z+/r) of lanthanide(Ⅲ) from La to Gd and from Tb to Lu, respectively, indicating the Gd break. There exist inclined W effect between Ig Kθ and the total angular momentum L of lanthanide(Ⅲ). And hereby lanthanide elements are divided into four segments, La-Nd, Pm-Gd, Tb-Ho, and Er-Lu. In each segment, the linearity is maintained.展开更多
A new Co(Ⅲ) complex with a tripodal amide ligand [CoL(N3)3] (L = N-acetyl- N',N'-bis-[(2-pyridyl)methyl]-ethylenediamine) has been synthesized and characterized structurally by X-ray diffraction. It crystal...A new Co(Ⅲ) complex with a tripodal amide ligand [CoL(N3)3] (L = N-acetyl- N',N'-bis-[(2-pyridyl)methyl]-ethylenediamine) has been synthesized and characterized structurally by X-ray diffraction. It crystallizes in orthorhombic, space group Pnma with a = 9.2515(19), b = 12.729(3), c = 17.273(4) A, V = 2034.0(7) A3, C16H20CoN13O, Mr = 469.38, Dc = 1.533 g/cm3, μ(MoKα) = 0.884 mm^-1, F(000) = 968, Z = 4, the final R = 0.0392 and wR = 0.0818 for 2430 observed reflections. In the complex, the amide ligand L acts as a tridentate fashion and coordinates to the Co(Ⅲ) ion through three nitrogen atoms, while the other three positions of the Co(Ⅲ) center are occupied by three terminal azide anions. The complex is connected as a 1D chain structure by intermolecular hydrogen bonds between the uncoordinated amide groups. In order to investigate the coordination ability, thermodynamic stability of the ligand L with the first-series transition metal ions (Co(Ⅱ), Ni(Ⅱ), Cu(Ⅱ) and Zn(Ⅱ)) has been studied by potentiometric titration, and the results show that the order of their stability constants conforms to the Irving-Williams sequence.展开更多
A potentiometric study on the complexes of His,Gly-His,ALa-His,Gly-Gly and Gly—Gly—Gly with Zn(Ⅱ)and Cd(Ⅱ)has been reported.Small-scale potentiometric titrations were car- ried out to determine stabil ity constant...A potentiometric study on the complexes of His,Gly-His,ALa-His,Gly-Gly and Gly—Gly—Gly with Zn(Ⅱ)and Cd(Ⅱ)has been reported.Small-scale potentiometric titrations were car- ried out to determine stabil ity constants of complexes at 25℃ with I=0.10 mol dm^(-3)(KNO_3).The com- puter programs SUPERQUAD were applied for data treatment with satisfactory results.展开更多
This paper reports the determination of stability constants for complexes of Cd(Ⅱ)with Gly, Ala,Val,Asp,Gly—Asp,Asp Gly,Gly—Gly and Gly—Gly—Gly using both micro—pH—metric titra- tions and the application of con...This paper reports the determination of stability constants for complexes of Cd(Ⅱ)with Gly, Ala,Val,Asp,Gly—Asp,Asp Gly,Gly—Gly and Gly—Gly—Gly using both micro—pH—metric titra- tions and the application of convolution—deconvolution cyclic voltammetry at 25℃ and I=0.10 mol· dm^(-3)(KNO_3).Stability constants were calculated from pH—metric data using the SUPERQUAD com- puter program and cyclic voltammograms were collected,stored and manipulated using the EG and G CONDECON 300 software.A considerably larger ligand:metal ratio(e,g.50:1)was possible using voltammetry.Evaluation of results from the two techniques suggests that stability constants for the species[CdL_2]and[CdL_3]are reliable when calculated fromvoltammetry while those for[CdL]are more reliable when determined by pH-metric titration.展开更多
In the existing Statistics and Econometrics literature, there does not exist a statistical test which may test for all kinds of roots of the characteristic polynomial leading to an unstable dynamic response, i.e., pos...In the existing Statistics and Econometrics literature, there does not exist a statistical test which may test for all kinds of roots of the characteristic polynomial leading to an unstable dynamic response, i.e., positive and negative real unit roots, complex unit roots and the roots lying inside the unit circle. This paper develops a test which is sufficient to prove dynamic stability (in the context of roots of the characteristic polynomial) of a univariate as well as a multivariate time series without having a structural break. It covers all roots (positive and negative real unit roots, complex unit roots and the roots inside the unit circle whether single or multiple) which may lead to an unstable dynamic response. Furthermore, it also indicates the number of roots causing instability in the time series. The test is much simpler in its application as compared to the existing tests as the series is strictly stationary under the null (C01, C12).展开更多
Rubber trees (Hevea brasiliensis Müll. Arg.) have been commercially cultivated for a century and a half in Asia, particularly in China, and they constitute a common element of plantation ecosystems in tropical re...Rubber trees (Hevea brasiliensis Müll. Arg.) have been commercially cultivated for a century and a half in Asia, particularly in China, and they constitute a common element of plantation ecosystems in tropical regions. Soil health is fundamental to the sustainable development of rubber plantations. The objective of the study is to explore the influence of different complex ecological cultivation modes on the stability of soil aggregates in rubber based agroforestry systems. In this study, the ecological cultivation mode of rubber—Alpinia oxyphylla plantation, the ecological cultivation mode of rubber—Phrynium hainanense plantations, the ecological cultivation mode of rubber—Homalium ceylanicum plantations and monoculture rubber plantations were selected, and the particle size distribution of soil aggregates and their water stability characteristics were analyzed. The soil depth of 0 - 20 cm and 20 - 40 cm was collected for four cultivation modes. Soil was divided into 6 particle levels > 20 cm. soil was divided into 6 particle levels > 5 mm, 2 - 5 mm, 1 - 2 mm, 0.5 - 1 mm, 0.25 - 0.5 mm, and 0.053 - 0.25 mm according to the wet sieve method. The particle size proportion and water stability of soil aggregates were determined by the wet sieve method. The particle size proportion and water stability of soil aggregates under different ecological cultivation modes were analyzed. The results showed that under different ecological cultivation modes in the shallow soil layer (0 - 20 cm), the rubber—Alpinia oxyphylla plantation and the rubber—Phrynium hainanense plantation promoted the development of dominant soil aggregates towards larger size classes, whereas the situation is the opposite for rubber—Homalium ceylanicum plantation. In soil layer (20 - 40 cm), the ecological cultivation mode of rubber—Phrynium hainanense plantation developed the dominant radial level of soil aggregates to the diameter level of large aggregates. Rubber—Alpinia oxyphylla plantation and rubber—Homalium ceylanicum plantation, three indicators, including the water-stable aggregate content R<sub>0.25</sub> (>0.25 mm water-stable aggregates), mean weight diameter (MWD), and geometric mean diameter (GMD), were all lower than those in the rubber monoculture mode. However, in the rubber—Phrynium hainanense plantation, the water-stable aggregate content R<sub>0.25</sub>, mean weight diameter, and geometric mean diameter were higher than in the rubber monoculture mode, although these differences did not reach statistical significance.展开更多
One novel binuclear copper(Ⅱ) complex [Cu 2 (Hpt) 2 (CO 3) 2 (H 2 O) 2 ]·H 2 O with copper carbonate and 3-(pyridin-2-yl)-1,2,4-triazole (Hpt) was hydrothermally synthesized and characterized by IR a...One novel binuclear copper(Ⅱ) complex [Cu 2 (Hpt) 2 (CO 3) 2 (H 2 O) 2 ]·H 2 O with copper carbonate and 3-(pyridin-2-yl)-1,2,4-triazole (Hpt) was hydrothermally synthesized and characterized by IR and X-ray diffraction analysis.The complex crystallizes in triclinic,space group P2 1 /n with a=0.6862(1),b=0.7805(1),c=1.1983(2) nm,α=72.03(2),β=107.72(3),γ=75.28(2)o,V=0.5884 nm 3,D c=2.105 g/cm 3,Z=1,F(000)=357,GOOF=1.041,the final R=0.01859 and wR=0.04348.The whole molecule is composed of two cooper ions,two Hpt molecules,two carbonate and three water molecules,forming a binuclear structure.The crystal structure shows that the cooper ion is coordinated with three nitrogen atoms from two Hpt molecules,two oxygen atoms from one carbonic acid and one water molecule,forming a distorted square pyramidal geometry.The TG analysis result shows that the title complex is stable under 131.0 ℃.展开更多
The nickel complex {Ni(2,2-bipy)(H2O)3[C8H11O2(COO)]}(H2O)3 with bicycle-[2.2.1]-2-hepten-5,6-dicarboxylic acid [C7H8(COOH)2] and 2,2'-bipyridine (bipy) as ligands has been synthesized and characterized. ...The nickel complex {Ni(2,2-bipy)(H2O)3[C8H11O2(COO)]}(H2O)3 with bicycle-[2.2.1]-2-hepten-5,6-dicarboxylic acid [C7H8(COOH)2] and 2,2'-bipyridine (bipy) as ligands has been synthesized and characterized. It crystallizes in monoclinic, space group P , with a = 0.74975(3), b = 1.20309(4), c = 1.30593(4) nm, α = 109.861(2), β = 98.519(2), γ = 90.575(2)o, V = 1.09337(7) nm3, Dc = 1.552 g/cm3, Z = 2, F(000) = 524, the final GOOF = 1.064, R = 0.0397 and wR = 0.1171. The crystal structure shows that the nickel ion is coordinated with four oxygen atoms from one bicycle[2.2.1]-2-hepten-5,6-dicarboxylic acid molecule and three water molecules and two nitrogen atoms from the 2,2′-bipyridine molecule, forming a distorted octahedral coordination geometry. The result of TG analysis shows that the title complex is stable under 200.0 ℃.展开更多
A new europium(III)complex Eu2(C15H11O3)6(C12H8N2)2 has been synthesized with 2-(4-Methylbenzoyl)benzoic acid and 1,10-phenanthroline as ligands.Crystal data for the complex are as follows:monoclinic,space group P21/n...A new europium(III)complex Eu2(C15H11O3)6(C12H8N2)2 has been synthesized with 2-(4-Methylbenzoyl)benzoic acid and 1,10-phenanthroline as ligands.Crystal data for the complex are as follows:monoclinic,space group P21/n,a=15.1238(5),b=13.5928(4),c=22.9840(7)?,β=104.132(3) ,V=4582.0(2)?3,Dc=1.522 g/cm3,Z=4,μ(MoKα)=1.433 mm-1,F(000)=2128,the final R=0.0447 and wR=0.0826.The Eu(III)ion is coordinated by eight atoms to give a distorted square antiprism coordination geometry.The complex shows two intense fluorescence emission bands arising from the transitions of Eu3+:5D0→7F1(594 nm)and 5D0→7F2(617 nm).The complex is an antiferromagnetism system in the range of 150~300 K.Also reported in the paper is the thermal stability property of the title complex.展开更多
Considering that there are some limitations in analyzing the anti-sliding seismic stability of dam-foundation systems with the traditional pseudo-static method and response spectrum method, the dynamic strength reduct...Considering that there are some limitations in analyzing the anti-sliding seismic stability of dam-foundation systems with the traditional pseudo-static method and response spectrum method, the dynamic strength reduction method was used to study the deep anti-sliding stability of a high gravity dam with a complex dam foundation in response to strong earthquake-induced ground action. Based on static anti-sliding stability analysis of the dam foundation undertaken by decreasing the shear strength parameters of the rock mass in equal proportion, the seismic time history analysis was carried out. The proposed instability criterion for the dynamic strength reduction method was that the peak values of dynamic displacements and plastic strain energy change suddenly with the increase of the strength reduction factor. The elasto-plastic behavior of the dam foundation was idealized using the Drucker-Prager yield criterion based on the associated flow rule assumption. The result of elasto-plastic time history analysis of an overflow dam monolith based on the dynamic strength reduction method was compared with that of the dynamic linear elastic analysis, and the reliability of elasto-plastic time history analysis was confirmed. The results also show that the safety factors of the dam-foundation system in the static and dynamic cases are 3.25 and 3.0, respectively, and that the F2 fault has a significant influence on the anti-sliding stability of the high gravity dam. It is also concluded that the proposed instability criterion for the dynamic strength reduction method is feasible.展开更多
A new dinuclear manganese complex [Mn2(L)2(2,2'-bipy)2(H2O)512·3H2O has been synthesized with MnSO4·H2O, 2,2'-bibenzoic acid (H2L) and 2,2'-bipyridine(2,2'-bipy) in the mixed solvent ethanol an...A new dinuclear manganese complex [Mn2(L)2(2,2'-bipy)2(H2O)512·3H2O has been synthesized with MnSO4·H2O, 2,2'-bibenzoic acid (H2L) and 2,2'-bipyridine(2,2'-bipy) in the mixed solvent ethanol and water. It crystallizes in monoclinic, space group Pi with a = 9.9944(10), b = 21.939(2), c = 25.628(3) A, a = 108.429(3), β = 100.613(4), 7 = 102.821(3)°, V = 4997.9(9) A3, Dc= 1.355 g/cm^3, Z = 2, F(000) = 2108, GOOF = 1.074, the R= 0.0626 and wR= 0.1531. The structure of the complex contains two [Mn2(L)2(2,2'-bipy)2] units, ten coordinated H2O molecules and three uncoordinated H2O molecules. The fluorescence, thermal stability and magnetic properties of the complex were investigated.展开更多
A new dinuclear copper(II) complex [Cu2(L)2(phen)2]·5H2O (1) with bicycle[2.2.1 ]hept- 2-en-5, 6-dicarboxylic acid (H2L) and 1,10-phenanthroline (phen) as ligands has been synthesized in the mixed sol...A new dinuclear copper(II) complex [Cu2(L)2(phen)2]·5H2O (1) with bicycle[2.2.1 ]hept- 2-en-5, 6-dicarboxylic acid (H2L) and 1,10-phenanthroline (phen) as ligands has been synthesized in the mixed solvents of ethanol and water. It crystallizes in the monoclinic space group P21/c, with a = 17.925(4), b = 19.908(4), c = 11.235(2) A, β = 97.65(3)°, V= 3973.4(14) A3, Dc = 1.552 g/cm^3, Z = 8, F(000) = 1910, the final GOOF = 1.056, R= 0.0519 and wR= 0.1293. The crystal structure shows that the whole molecule consists of two independent dinuclear units, in which two copper ions are bridged by twoμ2-η1 :η0-3-carboxylate groups of L^2- anions. The fluorescence and thermal stability properties of 1 were studied. The results show that 1 has an intense fluorescent emission at around 381 rim. The TG analysis shows that I is stable below 143 ℃.展开更多
A new complex Cu2(o-C6H5COC6H5COO)4(C10H8N2)2(H2O)2 with 2-benzoylben- zoic acid and 2,2′-bipyridine as ligands has been synthesized in mixed methanol and water solvent. Crystal data are as follows: monoclinic...A new complex Cu2(o-C6H5COC6H5COO)4(C10H8N2)2(H2O)2 with 2-benzoylben- zoic acid and 2,2′-bipyridine as ligands has been synthesized in mixed methanol and water solvent. Crystal data are as follows: monoclinic, space group Co, a = 14.0133(14), b = 16.0409(16), c = 30.372(3) A, β = 100.8950(10)°, V = 6704.1(12) A3, Dc = 1.364 g/cm3, Z = 8,μ(MoKa) = 0.704 mml, F(000) = 2840, the final R= 0.0552 and wR = 0.1431. In the crystal structure, the whole molecule consists of two copper ions, four 2-benzoylbenzoic acid molecules, two 2,2′-bipyridine molecules and two water molecules. Each central copper ion is coordinated with two nitrogen atoms from one 2,2′-bipyridine molecule and three oxygen atoms from two 2-benzoylbenzoic acids and one water molecule, respectively, giving a distorted tetragonal pyramidal geometry. Thermal stability properties of the complex were investigated.展开更多
The stability constants of the binary complexes of Mn2+ with nicotinamide (NA) were determined from potentiometric pH titrations data at 15.0 , 25.0 and 35.0oC and I = 0.1,0.2,0.4 mol L-1 (NaClO4). The formation of bi...The stability constants of the binary complexes of Mn2+ with nicotinamide (NA) were determined from potentiometric pH titrations data at 15.0 , 25.0 and 35.0oC and I = 0.1,0.2,0.4 mol L-1 (NaClO4). The formation of binary 1:1 , 1:2 NA-Mn complexes at three different temperatures and the influence of three different ionic strength on their stability were reported. The thermodynamic parameters (DGof, DSof, DHof) for the complex formation reaction were estimated from stability constant at different temperatures.展开更多
基金This project is financially supported by Natural Science Foundation of Hebei Province, China (No. 299193)
文摘Silica gel luminophors containing 1, 10-phenanthroline-tris(M-Methylbenzoate) europium (or terbium) com- plexes were prepared bysol-gel method. The thermal decomposition, excitation and emissionspectra for the gel phos- phors were measured and compared with thatof solid complex powders. The thermal stability of the complexes wasen- hanced in SiO_2 host matrix and the luminescence intensityremained unchanged.
基金Supported by Hunan Provincial Natural Science Foundation of China(2019JJ60021)the Scientific Research Found of Hunan Provincial Education Department of China(17A049,17C0226)Industry and Research Key Project of Hengyang City(2018KJ016)
文摘Two new cobalt(Ⅱ)complexes[Co2(2,2?-bipy)2(dpa)2(H2O)5]·4H2O(1)and Co(2,2?-bipy)3(SO4)]·7.5H2O(2)have been synthesized with diaphonic acid(H2dpa)and 2,2?-bipyridine(2,2?-bipy)as ligands.In 1,two neighboring cobalt(Ⅱ)ions are linked together by one bridging diaphonic acid group,forming an asymmetric dinuclear structure.1 crystallizes in triclinic,space group P1 with a=9.825(6),b=13.007(8),c=19.586(1)A,α=80.773(1)o,β=77.065(1)o,γ=85.902(1)o,Mr=431.4,V=2406.5(3)A^3,Dc=1.48 g/cm^3,Z=2,μ(Mo Kα)=0.767 mm-1,F(000)=1112,the final R=0.0379 and wR=0.0862.The central cobalt(Ⅱ)ions in 1 and 2 are coordinated with six atoms,forming distorted octahedral coordination geometry.The fluorescence and thermal stability properties of 1 and 2 are also reported.
文摘Ternary complexes of europium and terbium with benzoic acid and 1, 10 phenanthroline [RE(BA) 3phen] (BA=benzoate phen=1,10 phenanthroline) were introduced into a silica matrix by sol gel method. The thermal stability and luminescence behavior of the complexes in silica gels were studied in comparison with the corresponding solid state complexes by thermal decomposition, excitation and emission spectra. The thermal stability of the complexes is enhanced in silica gel matrix and the luminescence remaines unchanged.
基金supported by the Natural Science Foundation of China(No.21171165,21201165 and 91122015)
文摘A series of isostructural d/f molecular compounds Zn(H2L)Ln(NO3)3·CH3OH(Ln = Dy(1), Tb(2) and Sm(3)) were synthesized by the introduction of a designed multifunctional ligand N,N?,N??,N???-tetra(2-hydroxy-3-methoxy-5-methylbenzyl)-1,4,7,10-tetraazacyclododecan(H4L = C(44)H(60)N4O8). In the isostructural molecules, each crystallographically independent Zn2+ and Ln3+ centers are connected by two phenolic oxygen atoms. For the six-coordinate Zn-(2+) ion, the coordination geometry can be viewed as a regular bicapped square pyramid. While for the ten-coordinate Ln-(3+) ion, if each O,O?-chelated nitrate ligand is seen as a single coordination site, the coordination geometry can be viewed as a distorted pentagonal bipyramid. The fluorescent spectra show that compounds 2 and 3 exhibited characteristic sharp emissions of Tb-(3+) and Sm-(3+), respectively, while compound 1 was found to be a single-component white-light-emitting complex in the solid state. Thermal stabilities of the three compounds were investigated by using thermal gravimetric analysis. In addition, the thermal decomposition of compound 1 was confirmed by temperature-dependent powder X-ray diffraction technique.
基金The financial support from the Robert A. Welch Foundation (A-0259) in the U.S and China Scholarship Council (97837086) is gratefully acknowledged.
文摘The stability constants of the mononuclear complexes of BDBPH-Zn(II), Cd(II) and Mn (II) were determined by the potentiometric equilibrium measurements, and species distributions were also discussed. The metal ions do not combine with the ligand until the first two protons of the ligand have almost been completely neutralized. The main species were mononuclear complexes with the diprotonated ligand, MH,L. The three metal ions also form mono- and noprotonated (fully deprotonated) complexes, MHL, ML. The relative order of stabilities of the mononuclear complexes, ML, is Zn(II) > Cd(II) > Mn(II). The ligand has strong tendency to form mononuclear complexes with Zn(II), Cd(II) and Mn(II), and it can also form dinuclear complexes at high pH.
文摘The reactions LnCl3 (s) + (3/2)Al2Cl6, (g) = LnAl3Cl12 (g) for Ln = La to Lu were studied by quenching experiments in roughly the same temperature and pressure ranges (588-851 K and 0.01-0.22 MPa). Stability constants Kθ of lanthanide complexes LnAl3Cl12 were calculated from the measurements. The values of Ig Kθ change linearly with the ionpotential (Z+/r) of lanthanide(Ⅲ) from La to Gd and from Tb to Lu, respectively, indicating the Gd break. There exist inclined W effect between Ig Kθ and the total angular momentum L of lanthanide(Ⅲ). And hereby lanthanide elements are divided into four segments, La-Nd, Pm-Gd, Tb-Ho, and Er-Lu. In each segment, the linearity is maintained.
基金supported by the National Natural Science Foundation of China (No.20771083)
文摘A new Co(Ⅲ) complex with a tripodal amide ligand [CoL(N3)3] (L = N-acetyl- N',N'-bis-[(2-pyridyl)methyl]-ethylenediamine) has been synthesized and characterized structurally by X-ray diffraction. It crystallizes in orthorhombic, space group Pnma with a = 9.2515(19), b = 12.729(3), c = 17.273(4) A, V = 2034.0(7) A3, C16H20CoN13O, Mr = 469.38, Dc = 1.533 g/cm3, μ(MoKα) = 0.884 mm^-1, F(000) = 968, Z = 4, the final R = 0.0392 and wR = 0.0818 for 2430 observed reflections. In the complex, the amide ligand L acts as a tridentate fashion and coordinates to the Co(Ⅲ) ion through three nitrogen atoms, while the other three positions of the Co(Ⅲ) center are occupied by three terminal azide anions. The complex is connected as a 1D chain structure by intermolecular hydrogen bonds between the uncoordinated amide groups. In order to investigate the coordination ability, thermodynamic stability of the ligand L with the first-series transition metal ions (Co(Ⅱ), Ni(Ⅱ), Cu(Ⅱ) and Zn(Ⅱ)) has been studied by potentiometric titration, and the results show that the order of their stability constants conforms to the Irving-Williams sequence.
文摘A potentiometric study on the complexes of His,Gly-His,ALa-His,Gly-Gly and Gly—Gly—Gly with Zn(Ⅱ)and Cd(Ⅱ)has been reported.Small-scale potentiometric titrations were car- ried out to determine stabil ity constants of complexes at 25℃ with I=0.10 mol dm^(-3)(KNO_3).The com- puter programs SUPERQUAD were applied for data treatment with satisfactory results.
文摘This paper reports the determination of stability constants for complexes of Cd(Ⅱ)with Gly, Ala,Val,Asp,Gly—Asp,Asp Gly,Gly—Gly and Gly—Gly—Gly using both micro—pH—metric titra- tions and the application of convolution—deconvolution cyclic voltammetry at 25℃ and I=0.10 mol· dm^(-3)(KNO_3).Stability constants were calculated from pH—metric data using the SUPERQUAD com- puter program and cyclic voltammograms were collected,stored and manipulated using the EG and G CONDECON 300 software.A considerably larger ligand:metal ratio(e,g.50:1)was possible using voltammetry.Evaluation of results from the two techniques suggests that stability constants for the species[CdL_2]and[CdL_3]are reliable when calculated fromvoltammetry while those for[CdL]are more reliable when determined by pH-metric titration.
文摘In the existing Statistics and Econometrics literature, there does not exist a statistical test which may test for all kinds of roots of the characteristic polynomial leading to an unstable dynamic response, i.e., positive and negative real unit roots, complex unit roots and the roots lying inside the unit circle. This paper develops a test which is sufficient to prove dynamic stability (in the context of roots of the characteristic polynomial) of a univariate as well as a multivariate time series without having a structural break. It covers all roots (positive and negative real unit roots, complex unit roots and the roots inside the unit circle whether single or multiple) which may lead to an unstable dynamic response. Furthermore, it also indicates the number of roots causing instability in the time series. The test is much simpler in its application as compared to the existing tests as the series is strictly stationary under the null (C01, C12).
文摘Rubber trees (Hevea brasiliensis Müll. Arg.) have been commercially cultivated for a century and a half in Asia, particularly in China, and they constitute a common element of plantation ecosystems in tropical regions. Soil health is fundamental to the sustainable development of rubber plantations. The objective of the study is to explore the influence of different complex ecological cultivation modes on the stability of soil aggregates in rubber based agroforestry systems. In this study, the ecological cultivation mode of rubber—Alpinia oxyphylla plantation, the ecological cultivation mode of rubber—Phrynium hainanense plantations, the ecological cultivation mode of rubber—Homalium ceylanicum plantations and monoculture rubber plantations were selected, and the particle size distribution of soil aggregates and their water stability characteristics were analyzed. The soil depth of 0 - 20 cm and 20 - 40 cm was collected for four cultivation modes. Soil was divided into 6 particle levels > 20 cm. soil was divided into 6 particle levels > 5 mm, 2 - 5 mm, 1 - 2 mm, 0.5 - 1 mm, 0.25 - 0.5 mm, and 0.053 - 0.25 mm according to the wet sieve method. The particle size proportion and water stability of soil aggregates were determined by the wet sieve method. The particle size proportion and water stability of soil aggregates under different ecological cultivation modes were analyzed. The results showed that under different ecological cultivation modes in the shallow soil layer (0 - 20 cm), the rubber—Alpinia oxyphylla plantation and the rubber—Phrynium hainanense plantation promoted the development of dominant soil aggregates towards larger size classes, whereas the situation is the opposite for rubber—Homalium ceylanicum plantation. In soil layer (20 - 40 cm), the ecological cultivation mode of rubber—Phrynium hainanense plantation developed the dominant radial level of soil aggregates to the diameter level of large aggregates. Rubber—Alpinia oxyphylla plantation and rubber—Homalium ceylanicum plantation, three indicators, including the water-stable aggregate content R<sub>0.25</sub> (>0.25 mm water-stable aggregates), mean weight diameter (MWD), and geometric mean diameter (GMD), were all lower than those in the rubber monoculture mode. However, in the rubber—Phrynium hainanense plantation, the water-stable aggregate content R<sub>0.25</sub>, mean weight diameter, and geometric mean diameter were higher than in the rubber monoculture mode, although these differences did not reach statistical significance.
基金Supported by the Hunan Provincial Department of Science and Technology Project (2009FJ3101)
文摘One novel binuclear copper(Ⅱ) complex [Cu 2 (Hpt) 2 (CO 3) 2 (H 2 O) 2 ]·H 2 O with copper carbonate and 3-(pyridin-2-yl)-1,2,4-triazole (Hpt) was hydrothermally synthesized and characterized by IR and X-ray diffraction analysis.The complex crystallizes in triclinic,space group P2 1 /n with a=0.6862(1),b=0.7805(1),c=1.1983(2) nm,α=72.03(2),β=107.72(3),γ=75.28(2)o,V=0.5884 nm 3,D c=2.105 g/cm 3,Z=1,F(000)=357,GOOF=1.041,the final R=0.01859 and wR=0.04348.The whole molecule is composed of two cooper ions,two Hpt molecules,two carbonate and three water molecules,forming a binuclear structure.The crystal structure shows that the cooper ion is coordinated with three nitrogen atoms from two Hpt molecules,two oxygen atoms from one carbonic acid and one water molecule,forming a distorted square pyramidal geometry.The TG analysis result shows that the title complex is stable under 131.0 ℃.
基金Project supported by the Fund of Hunan Provincial Natural Science Foundation of China (No.11JJ9006)the Fund of Science and Technology Committee of Hunan Province (2009FJ3031)
文摘The nickel complex {Ni(2,2-bipy)(H2O)3[C8H11O2(COO)]}(H2O)3 with bicycle-[2.2.1]-2-hepten-5,6-dicarboxylic acid [C7H8(COOH)2] and 2,2'-bipyridine (bipy) as ligands has been synthesized and characterized. It crystallizes in monoclinic, space group P , with a = 0.74975(3), b = 1.20309(4), c = 1.30593(4) nm, α = 109.861(2), β = 98.519(2), γ = 90.575(2)o, V = 1.09337(7) nm3, Dc = 1.552 g/cm3, Z = 2, F(000) = 524, the final GOOF = 1.064, R = 0.0397 and wR = 0.1171. The crystal structure shows that the nickel ion is coordinated with four oxygen atoms from one bicycle[2.2.1]-2-hepten-5,6-dicarboxylic acid molecule and three water molecules and two nitrogen atoms from the 2,2′-bipyridine molecule, forming a distorted octahedral coordination geometry. The result of TG analysis shows that the title complex is stable under 200.0 ℃.
基金supported by the cooperative project of Hengyang Normal University with Hengyang Yile New Materials Co.,Ltd.(No.HXKJ201905)
文摘A new europium(III)complex Eu2(C15H11O3)6(C12H8N2)2 has been synthesized with 2-(4-Methylbenzoyl)benzoic acid and 1,10-phenanthroline as ligands.Crystal data for the complex are as follows:monoclinic,space group P21/n,a=15.1238(5),b=13.5928(4),c=22.9840(7)?,β=104.132(3) ,V=4582.0(2)?3,Dc=1.522 g/cm3,Z=4,μ(MoKα)=1.433 mm-1,F(000)=2128,the final R=0.0447 and wR=0.0826.The Eu(III)ion is coordinated by eight atoms to give a distorted square antiprism coordination geometry.The complex shows two intense fluorescence emission bands arising from the transitions of Eu3+:5D0→7F1(594 nm)and 5D0→7F2(617 nm).The complex is an antiferromagnetism system in the range of 150~300 K.Also reported in the paper is the thermal stability property of the title complex.
基金supported by the National Basic Research Program of China (973 Program,Grant No.2007CB714104)the National Natural Science Foundation of China (Grant No. 50779011)the Innovative Project for Graduate Students of Jiangsu Province (Grant No. CX09B_155Z)
文摘Considering that there are some limitations in analyzing the anti-sliding seismic stability of dam-foundation systems with the traditional pseudo-static method and response spectrum method, the dynamic strength reduction method was used to study the deep anti-sliding stability of a high gravity dam with a complex dam foundation in response to strong earthquake-induced ground action. Based on static anti-sliding stability analysis of the dam foundation undertaken by decreasing the shear strength parameters of the rock mass in equal proportion, the seismic time history analysis was carried out. The proposed instability criterion for the dynamic strength reduction method was that the peak values of dynamic displacements and plastic strain energy change suddenly with the increase of the strength reduction factor. The elasto-plastic behavior of the dam foundation was idealized using the Drucker-Prager yield criterion based on the associated flow rule assumption. The result of elasto-plastic time history analysis of an overflow dam monolith based on the dynamic strength reduction method was compared with that of the dynamic linear elastic analysis, and the reliability of elasto-plastic time history analysis was confirmed. The results also show that the safety factors of the dam-foundation system in the static and dynamic cases are 3.25 and 3.0, respectively, and that the F2 fault has a significant influence on the anti-sliding stability of the high gravity dam. It is also concluded that the proposed instability criterion for the dynamic strength reduction method is feasible.
基金Supported by the Key Project of Science and Technology Plan of Hunan Province(2012FJ2002)Science and Technology Committee of Hengyang(2013KG77)the Construct Program of the Key Discipline in Hunan Province
文摘A new dinuclear manganese complex [Mn2(L)2(2,2'-bipy)2(H2O)512·3H2O has been synthesized with MnSO4·H2O, 2,2'-bibenzoic acid (H2L) and 2,2'-bipyridine(2,2'-bipy) in the mixed solvent ethanol and water. It crystallizes in monoclinic, space group Pi with a = 9.9944(10), b = 21.939(2), c = 25.628(3) A, a = 108.429(3), β = 100.613(4), 7 = 102.821(3)°, V = 4997.9(9) A3, Dc= 1.355 g/cm^3, Z = 2, F(000) = 2108, GOOF = 1.074, the R= 0.0626 and wR= 0.1531. The structure of the complex contains two [Mn2(L)2(2,2'-bipy)2] units, ten coordinated H2O molecules and three uncoordinated H2O molecules. The fluorescence, thermal stability and magnetic properties of the complex were investigated.
基金Supported by the Construct Program of the Key Discipline in Hunan Province and Key Project of Production Plan of Hengyang City(2013)
文摘A new dinuclear copper(II) complex [Cu2(L)2(phen)2]·5H2O (1) with bicycle[2.2.1 ]hept- 2-en-5, 6-dicarboxylic acid (H2L) and 1,10-phenanthroline (phen) as ligands has been synthesized in the mixed solvents of ethanol and water. It crystallizes in the monoclinic space group P21/c, with a = 17.925(4), b = 19.908(4), c = 11.235(2) A, β = 97.65(3)°, V= 3973.4(14) A3, Dc = 1.552 g/cm^3, Z = 8, F(000) = 1910, the final GOOF = 1.056, R= 0.0519 and wR= 0.1293. The crystal structure shows that the whole molecule consists of two independent dinuclear units, in which two copper ions are bridged by twoμ2-η1 :η0-3-carboxylate groups of L^2- anions. The fluorescence and thermal stability properties of 1 were studied. The results show that 1 has an intense fluorescent emission at around 381 rim. The TG analysis shows that I is stable below 143 ℃.
基金Supported by the Natural Science Foundation of Hunan Province (No. 11JJ9006)Key Project of Science and Technology Plan of Hunan Province (2012FJ2002)+1 种基金Science and Technology Plan of Hunan Province (2012GK3031, 2012WK3029)the Construct Program of Key Discipline in Hunan Province
文摘A new complex Cu2(o-C6H5COC6H5COO)4(C10H8N2)2(H2O)2 with 2-benzoylben- zoic acid and 2,2′-bipyridine as ligands has been synthesized in mixed methanol and water solvent. Crystal data are as follows: monoclinic, space group Co, a = 14.0133(14), b = 16.0409(16), c = 30.372(3) A, β = 100.8950(10)°, V = 6704.1(12) A3, Dc = 1.364 g/cm3, Z = 8,μ(MoKa) = 0.704 mml, F(000) = 2840, the final R= 0.0552 and wR = 0.1431. In the crystal structure, the whole molecule consists of two copper ions, four 2-benzoylbenzoic acid molecules, two 2,2′-bipyridine molecules and two water molecules. Each central copper ion is coordinated with two nitrogen atoms from one 2,2′-bipyridine molecule and three oxygen atoms from two 2-benzoylbenzoic acids and one water molecule, respectively, giving a distorted tetragonal pyramidal geometry. Thermal stability properties of the complex were investigated.
文摘The stability constants of the binary complexes of Mn2+ with nicotinamide (NA) were determined from potentiometric pH titrations data at 15.0 , 25.0 and 35.0oC and I = 0.1,0.2,0.4 mol L-1 (NaClO4). The formation of binary 1:1 , 1:2 NA-Mn complexes at three different temperatures and the influence of three different ionic strength on their stability were reported. The thermodynamic parameters (DGof, DSof, DHof) for the complex formation reaction were estimated from stability constant at different temperatures.