NEXT NEAREST NEIGHBOR EFFECT ON TETRAHEDRAL FERROUS AND OCTAHEDRAL FERRIC IRON IN CHROMITE

Four chromites have been studied by using Mssbauer spectroscopy. Of the spectra of four chromites studied, three spectra aro fitted to three or four Fe~(2+) doublets in the tetrahedral A sites and one or two Fe~(3+) doublets in the tetrahedral A sites and octahedral B sites. The fourth spectrum is fitted to one Fe~(3+) doublet in the A sites and two Fe~(3+) doublets in tho B sites. Constant isomer shifts of approximately 0.9 mm/s for Fe~(2+) ions in the A sites and 0.3 mm/s for Fe~(3+) ions in the B sites as well as gradual changing quadrupole splitting for both of the A sites and the B sites are obtained. The binomial distributions in the B sites are ealeulated. Next nearest neighbor effect is used to explain the multiple doublets caused by Fe~(2+) ions in the A sites in the spectra of chromites Ⅰ, Ⅱ, Ⅲ and by Fe~(3+) ions in the B sites in the spectrum of chromite Ⅳ.     

Crystal Structure and Property Research on Compounds Co（Ⅱ） and Zn（Ⅱ） with 3-Methylbenzoic Acid

Two compounds with 3-methylbenzoic acid(HL) [Co(L)2(4,4'-bipy)]n 1 and [Zn2(L)4(4,4'-bipy)]n 2(L = 3-methylbenzoic acid) have been hydrothermally synthesized directly and characterized by single-crystal X-ray diffraction analysis,elemental analyses,IR spectra and ultraviolet-visible diffuse reflection integral spectra(UV-Vis DRIS).The two compounds are both one-dimensional infinite chains.The structural difference is that 1 is a double-chain structure and 2 is only a single chain one.At the same time,the carboxylate groups adopt different modes in the two compounds,relatively.Additionally,in order to explore the structural characteristic,two-dimen-sional IR spectra are investigated for 1 and 2.Photo-luminescent property of 2 is also researched in detail.     

Crystal structures and thermal decomposition mechanism of four lanthanide complexes with halogen-benzoic acid and 1,10-phenanthroline

This paper describes syntheses and structure determination of four lanthanide complexes [Nd(2-Cl-4-FBA) 3 phen] 2 (1, 2-Cl-4-FBA = 2-chloro-4-fluorobenzoate, phen = 1,10-phenanthroline), [Ln(2,5-DClBA) 3 phen] 2 (Ln = Sm(2) and Tb(3), 2,5-DClBA = 2,5-dichlorobenzoate) and [Sm(2-Cl-4,5-DFBA) 3 (phen)(H 2 O)] 2 (4, (2-Cl-4,5-DFBA = 2-chloro-4,5-difluorobenzo- ate). The complexes were characterized by elemental analysis, infrared and ultraviolet spectra, and X-ray single-crystal diffraction. In the molecular structures of 1 4, two Ln 3+ ions are linked by four carboxyl groups, with two of them in a bridging bidentate mode and the other two in a bridging-chelating tridentate mode, forming four binuclear molecules. In addition, each Ln 3+ ion is also chelated to one phen molecule and one carboxyl group in the complexes, except each Sm 3+ ion in 4 which is bonded to one carboxyl group by unidentate mode and one H 2 O molecule. There are two different coordination polyhedrons for each Nd 3+ ion in the two similar molecular structures of 1 and they are a distorted monocapped square antiprismatic and a distorted tricapped triangular prism conformation, respectively. The coordination polyhedron for each Ln 3+ ion in 2 4 is a nine-coordinated distorted mono-capped square antiprismatic conformation. The complex 3 exhibits green luminescence under the radiation of UV light. The thermal decomposition behaviors of the complexes have been discussed by simultaneous TG/DSC-FTIR technique. The 3D surface graphs for the FTIR spectra of the evolved gases were recorded and the gaseous products were identified by the typical IR spectra obtained at different temperatures from the 3D surface graphs. Meanwhile, we discussed the nonisothermal kinetics of 1 4 by the integral isoconversional non-linear (NL-INT) method.     

Crystal Structure and Luminescence of Eu(DBM)_3TPPO Complex

The crystal structure of tris(dibenzoylmethanato)(triphenylphosphine oxide)europium (Ⅲ), C63H51O7PEu, has been determined by single crystal X-ray diffraction. The complex crystallizes in the tri-clinic space group P 1 with two molecules in a unit cell. The cell dimensions are a=12. 336 (3), b=18. 729 (5), c=11. 502 (3) A, α=95. 86 (2), β=103.14 (2), γ=87.89 (2)0. The total number of 6969 independent reflections was used for the structure determination. The final calculated R value is 0. 055. The central europium ion is hepta-coordinated by seven oxygen atoms. The polyhedron is a distorted capped trigonal prism with the Eu-O separation of 2. 305-2. 367 A. The high resolution excitation and emission spectra measured at 77 K indicate two Eu (Ⅲ) sites in the complex. The symmetries of the Eu (Ⅲ) sites are C2v and Cs respectively. The lower symmetrical Cs site predominates. A comparison of the emission spectra for Gd(DBM)3TPPO doped by 1% Eu(Ⅲ) with those for Eu(DBM)3TPPO complex shows no significant     

INFRARED SPECTRA AND X- RAY DIFFRACTION ANALYSIS OF TAUTOMER AND CONFORMATIONS OF HEXAHYDRO- THIADIAZA-PHOSPHORIN-5 ONES

<正> The structures of hexahydro-2-aryloxy-2-thiono-3-methyl 1,3,4,2-thiadiazaphosphorin-5-ones have been studied by means of IR spectra and X-ray diffraction method. The IR spectra show that the C=O absorption of the keto-form(la) is near 1715cm-1 and C=N absorption of enol-form near 1660cm-1. The crystals are monoclinic with space group P21/a,a= 14. 029(3) ,b=8. 353(2) ,c=23. 353(6) A ,β= 107. 01 2)°. There are four pairs of molecules in keto- (1a) and enol-form (1b) per unit cell. The C=O and C(2)- N(2) distances of keto-form are 1. 21 and 1. 37 A Respectively, While the C(2)-O and C(2) = N(2) distances of enol-form 1. 316 and 1. 326A respec-evely. The rings of hexahydro-1,3,4,2-thiadiazaphosphorine for keto- and enol-form are toth in boat conformation.     

Synthesis and characterization of trisubstituted heteropolytungstogermanates containing group 3A elements

Six new compounds, α,β-KaHb[GeW9M3(H2O)3O37].xH2O(M = Al, Ga,In; a + b =7) and α-K9H5[Ge2W18Ga6(H2O)3O74].20H2O, were synthesized from the lacunary precursors α and β-GeW9O34 10- and characterized by elemental analysis, spectroscopy and electrochemistry. Tungsten-183 NMR spectra of the title complexes consist of two lines with intensity ratio 2:1 as expected for trisubstituted heteropoly anions. The intensity ratio of α-Ga compound is 1:2, which is different from others(2:1). With the help of FAB mass spectrum, we concluded that it is a dimer with D3h, structure in aqueous, and the others exist by monomers with C3c structures.     

SIMULTANEOUS DETERMINATION OF NEODYMIUM AND PRASEODYMIUM BY ZERO-ORDER AND FOURTH-ORDER DFRIVATIVE SPECTROPHOTOMETRY

With derivative spectrophotometric method,the complexes oflanthanides with 2-(5-bromo-2-pyridylazo)-5-diethylaminophen-ol(5-Br-PADAP)in the presence of octylphenol poly(ethyleneg-lycol)ether(TX-100)were studied.It is found that the maximumabsorption of fourth-order derivative spectra of the neodymiumcomplex by 4f electron transitions is at 579(+)nm and 582(-)nmwith molar derivative absorptivities of 5.2×10~3 1.mol~(-1).cm~(-1).The maximum absorption of the zero-order derivative spectra ofthe complexes for neodymium and praseodymium is at 580hm,themolar absorptivities are 1.47×10~5 l.mol~(-1).cm~(-1)for Nd and 1.26×10~5 l.mol~(-1).cm~(-1)for Pr.The component ratio of the complexis Nd:5-Br-PADAP=1:4.Beer's law is obeyed in the range of0-3.75μg of Nd and Pr in 25ml of solution.The method has beenused for the simultaneous determination of Nd and Pr in foursynthetic samples and the results obtained are satisfactory.     

Studies on the Electronic Structures and Spectra of C78（CH2）3

The structures and spectra of 20 possible isomers of C78(CH2)3 have been studied by using AM1,INDO/CIS and DFT methods. The results show that the most stable isomer is 1,2,3,4,5,6-C78(CH2)3 (A) with annulene structures,where three -CH2 groups are added to the 6/6 bonds located at the same hexagon passed by the shortest axis of C78 (C2v). Compared with that of C78 (C2v),the first absorption in the electronic spectrum of C78(CH2)3 (A) is blue-shifted because of its wider LUMO-HOMO energy gap. While the IR frequencies of the C–C bonds on the carbon cage are red-shifted owing to the formation of annulene structures and the extension of the conjugated system. The chemical shifts of the carbon atoms in 13C NMR spectra are moved upfield upon the addition.     

Structure and electrospray mass spectrometry studies on dithiacyclooctan-3-ol-containing palladium (II) complex of trans -[Pd(dtco-3-OH)_2](ClO_4)_2·2DMSO

The structure of trans-[Pd(dtco-3-OH)2] (ClO4)2·2DMSO, in which dtco-3-OH is dithiacyclooctan-3-ol and DMSO is dimethyl sulfoxide, was determined by X-ray crystallographic analysis. The crystal data: space group pi, a = 0.7077(2) nm, b = 1.0788(1) nm, c = 1.1111(1) nm, α=67.710(8)°, β = 73. 59(2)°, γ = 85. 39(2)°,R1 = 0 . 0368 and Rw = 0.0998. The palladium (II) is coordinated by four sulfur atoms with a regular square planar configuration. The Pd-S distances are 0.2314(1) and 0.2317(1) nm, respectively. Both dtco-3-OH ligands are in the boat-chair configuration and two hydroxyl groups are on the opposite sites of the PdS4 coordination plane and are towards Pd(II). The Pd-O distance is 0. 285 nm, indicating a weak interaction between them. A typical hydrogen bond between the hydroxyl group of dtco-3-OH ligand and DMSO was observed in the crystal structure. An aqueous solution prepared with the crystals of the complex was used for the investigation of electrospray mass spectrometry ( ESMS ). Besid     

DFT Studies on Non-IPR C_(68) and Endohedral Fullerene Sc_3N@C_(68)

The structures and spectra of 20 possible isomers of C78(CH2)3 have been studied by using AM1,INDO/CIS and DFT methods. The results show that the most stable isomer is 1,2,3,4,5,6-C78(CH2)3 (A) with annulene structures,where three -CH2 groups are added to the 6/6 bonds located at the same hexagon passed by the shortest axis of C78 (C2v). Compared with that of C78 (C2v),the first absorption in the electronic spectrum of C78(CH2)3 (A) is blue-shifted because of its wider LUMO-HOMO energy gap. While the IR frequencies of the C–C bonds on the carbon cage are red-shifted owing to the formation of annulene structures and the extension of the conjugated system. The chemical shifts of the carbon atoms in 13C NMR spectra are moved upfield upon the addition.     

STRUCTURE-REACTIVITY STUDIES ON THE EXTRACTION OF RARE EARTHS BY DIALKYL ISOPROPYLPHOSPHONATES

Dialkyl isopropylphosphonates with various alkyl groups are synthesized for the structure-reactivity studies on the extraction of rare earths. Steric effect of ligands on the extrac-tion behaviour of rare earth is well demonstrated due to the lanthanide contraction. Thethermodynamic functions of the extraction reaction are estimated and the influence of chem-ical structure of extractants is discussed. By the method of continuous variation as well asthe elementary analysis, the composition of the extracted species is deduced as Ln(NO_3)_3·3L.The structure of the coordination compound is further elucidated by IR and NMR spectra.The magnetic property and the differential thermal analysis of the complexes are also studied.     

Synthesis of 1,3,4-Diazaphospholidin-2-One-4-Oxides by Mannich-Type Reaction and Structure Analysis of Products

The Mannich-type reaction of phenylurea with phenyl dichlorophosphine and aldehydes (or ketones) is studied in this paper. It is found that straight chain and cyclic products are obtained respectively, when different solvents are used.The ways of cyclization are affected by the substituents of ketones.There exist two geometrical isomers for each of the title compounds which are proved by their ~1H NMR and ~(31)P NMR spectra, and the configuration of each isomer is confirmed by means of X-ray diffraction and ~1H NMR spectra. Besides, it is found that the five-membered phosphorus heterocycle is of a plane conformation with a dπ-pπ bond between P and N.     

The synthesis and characterization of organometallic copolymers with Mn-Re binuclear transition-metal group in the side chain

Novel organometallic copolymers with Mn-Re binuclear transition-metal groups in the side chain are synthesized and characterized. The structure and properties of the copolymers are characterized by GPC, DSC, TG, NMR, FT-IR, UV-Vis spectra and elemental analysis. The glass transition temperature and UV-Vis spectra properties of these three organometallic copolymers are found to be different from the normal polystyrene. New synthetic strategy for the synthesis of or-ganometallic copolymer is developed.     

Synthesis of Novel Carbosilane Dendrimers Based on Pentaerythritol

Novel pentaerythritol-based carbosilane dendrimers centered at carbon have been synthesised. Starting from tetraallyl ether based upon pentaerythritol as the core molecule, a succession of alternate Pt-catalyzed hydrosilylation of allyl groups with HSiC13 and allylations of SiC1 groups thus introduced with CH2=CHCH2MgBr in THF provided a divergent synthesis of three generations of carbosilane dendrimers in which the Si atoms are linked by CH2CH2CH2 groups. The reaction conditions for hydrosilylation must be well controlled. After purification by chromatography on silica gel pure products for each generation were obtained. The IR, ^1H and ^13C NMR spectra and elemental analysis data are consistent with the proposed structures. The molecular weights of the resulting carbosilne dendrimers have been determined by vapor pressure osmometry.     

Synthesis, Crystal Structure, Fluorescence Property and Antibacterial Activity of Two Unprecedented One-dimensional Chain Metal organic Coordination Polymers： Zn（H-SSA）（Phen）（H20）2 and Cu（H-SSA） （Phen） （H20）2

The reaction of 5-sulfosalicylic acid(H3-SSA) with o-phenanthroline(Phen),NaOH,and Mcl2(M=Zn,Cu) affords Zn(H-SSA)(Phen)(H2O)2(1) and Cu(H-SSA)(Phen)(H2O)2 (2),respectively ,compounds 1 and 2 are characterized by elemental analysis,IR,fluorescence spectra and single crystal Xray diffraction analysis.The X-ray diffraction analyses reveal that compounds 1 and 2 are isostructure.The 5-sulfosalicylic acid ligand loses two protons at the sulfo-group and carboxylic group during the reaction.The Zn(II) and Cu(II)ions are sixcoordinated and adopt distorted octahedral geometry,which are surrounded by two N atoms from Phen,two O atoms from two water molecules,one O atom from-SO3 group and one oxygen from carboxylic group of the other H-SSA.Compounds 1 and 2 have unprecedented one-dimensional linear chain formed by a repeating mononuclear structureal unit.which is bridged by H-SSA.The fluorescence intensity of 1 and 2 is stronger than that of Phen and H3-SSA at 400nm.The lowest excited single states of these complexes are assigned as mainly Phen localized 1(π π),The antibacterial activity test shows that compounds 1 and 2 strongly inhibit the growth of Streptococcus haemolyticus,Straphylococcus aureus and Escherichia coli.     

CRYSTAL AND MOLECULAR STRUCTURE OF COMPLEX OF 1,2-CYCLOHEXYL-12-CROWN-4 WITH EUROPIUM NITRATE

<正> C12H22O4Eu(NO3)3,Mr=568. 28,monoclinic, P21/n,a=7. 980(1) ,6= 17.226(2), c=14. 460(3) A,B=100.15(1) , V= 1956. 6A3,Z=4,Dc=1.929 g/cm3,F(000) = 1128. The structure was sieved by direct methods and Fourier synthesis, and refined by block-diagonal and full matrix least-squares method to a final R of 0. 055 for 2568 independent reflections of I>3a(I). The ten donor oxygen atoms in the crowm ether and NO3 groups are coordinated to central metal ion Eu(III) forming an irregular coordination polyhedron. The Eu(III) ion is out of the ether oxygen plane and the three nitrate groups are bidentately coordinated to the Eu (III) on the opposite side of the polyether. The average bond lengths of Eu-O(NO3) and Eu-O(ether) are 2. 491A and 2. 558A ,respectively.     

SYNTHESIS, CHARACTERIZATION AND STRUCTURE OF [Co(DBP)_2·3Py]_2·2CHCl_3

The mixed ligand complex of cobalt with dibutylphosphate (HDBP) and pyridine has been synthesized. Elemental analysis yields the result that the formula of this compound is Co(DBP)_2·3Py·CHCl_3 (Py=pyridine). The thermal analsyis, visible spectra and magnetic properties of it have been studied as well. Single crystal structural analysis shows that the crystal is triclinic with space group P and the unit cell parameters are as follows:a=14.490(10), α=90.37(4)°,b=15.721(7), β=96.04(5)°,c=20.109(12), γ=105.63(4)°.The final R factor is 0.0773. Two Co atoms are connected by two bridging DBP groups to form a dinuclear molecule [Co(DBP)_2·3Py]_2 which has a C_s, symmetry. Each cell contains two dinuclear molecules and four chloroform molecules. The cobalt is coordinated in an octahedral arrangement by three oxygen atoms and three nitrogen atoms, of which one oxygen atom comes from a monodentate DBP group, two oxygen atoms from two bridging DBP groups, and the three nitrogen atoms from the three pyridi     

Luminescent properties of Ba_3(PO_4)_2:Eu,Tb phosphors

Luminescence of europium (Ⅲ),europium(Ⅱ) and terbium(Ⅲ) has been observed in Bas(PO4)2:Eu,Tb phosphors which are synthesized in air atmosphere.The valence state of europium is influenced by amount of terbium.It is notable that the relative intensity of the emission spectra peaks corresponding to Eu2+ is increased if the amount of Tb3+ is increased.These phenomena can be explained by an electron transfer mechanism.We predict a new kind of two-rare-earth codoped trichromatic phosphors in Ba3(PO4)2 matrix.     

Theoretical study of the mechanism for C-H bond activation in spin-forbidden reaction between Ti~+ and C_2H_4

The mechanism of the spin-forbidden reaction Ti+(4F, 3d24s1) + C2H4 → TiC2H2+ (2A2) + H2 on both doublet and quartet potential energy surfaces has been investigated at the B3LYP level of theory. Crossing points between the potential energy surfaces and the possible spin inversion process are discussed by means of spin-orbit coupling (SOC) calculations. The strength of the SOC between the low-lying quartet state and the doublet state is 59.3 cm-1 in the intermediate complex IM1-4B2. Thus, the changes of its ...     

11-Mercaptoundecanoic acid functionalized gold nanoclusters as fluorescent probes for the sensitive detection of Cu2+ and Fe3+ ions

Metal ions are physiologically essential,but excessive metal ions may cause severe risk to plants and animals.Here,we prepared gold nanoclusters(Au NCs) protected by 11-mercaptoundecanoic acid(11-MUA),which have excellent fluorescence properties for the detection of metal ions.The results showed that the copper ions(Cu~(2+)) and iron ions(Fe~(3+)) in the solution have obvious quenching effect on the fluorescence intensity of Au NCs.The detection range of Fe~(3+) was 0.8–4.5 mmol/L(R~2= 0.992) and 4.5–11.0 mmol/L(R~2= 0.997).And Cu~(2+) has a lower linear range(0.1–1.0 mmol/L,R2= 0.993).When EDTA was added into the reaction system,it was observed that the quenching effect of Cu~(2+) and Fe~(3+)on Au NCs showed different phenomenon.Then,the effect of metal ions on the fluorescence of Au NCs was investigated.The selective detection of Cu~(2+) was achieved by EDTA masking of Fe~(3+).In addition,we realized the metal ions detection application of Au NCs in the serum