~1H-~(27)Al CP/MAS NMR STUDIES OF DEALUMINATED HZSM-5 ZEOLITE

Recently introduced method of ~1H-~(27)Al CP/MAS was used to study the dealuminated HZSM-5 zeolite. The experimental result suggests that the resonance signal at ca. 30ppm is an independent signal (not part of a second-order quadrupolar lineshape), probably resulted from 5-coordinated non-framework aluminium (Al~(NFP)). The coincidence of the peaks of 4-coordinated framework (Al~F) and 4-coordinated non-framework (Al~(NF)) aluminium at 60ppm was confirmed by ~(27)Al MAS NMR after treating the dealuminated sample with acetylacetone (acac).     

Novel Monomeric Phenanthroline - Thallium(III) Complexes Multinuclear NMR Characterization in Organic Solvents

Thallium(III) complexes with nitrogen donor ligands constitute an interesting field in coordination chemistry. Phenanthroline is an extremely stiff organic ligand. The stability constants of its coordination compounds with Tl(III) have been investigated in aqueous solution by potentiometer1. 205Tl NMR technique has provided an effective method to study the thallium(III) solution chemistry. Thallium(III) coordination chemistry has attracted considerable attention recently for its ric…     

Synthesis, DNA-binding and photocleavage studies of ruthenium(Ⅱ) complexes [Ru(btz)_3]~(2+) and [Ru(btz)(dppz)_2]~(2+)

Two new ruthenium(Ⅱ) complexes, [Ru(btz)3](ClO4)2 (1) and [Ru(btz)(dppz)2](ClO4)2 (2) (btz = 4,4′-bithi-azole, dppz = dipyrido[3,2-a:2′,3′-c]phenazine), have been synthesized and characterized by elemental analysis, 1H NMR, ES-MS and X-ray crystallography. The DNA binding behaviors of two complexes have been studied by spectroscopic and viscosity measurements. The results suggest that complex 1 binds to CT-DNA via an electrostatic mode, while complex 2 via an intercalative mode. Under irradiation at 365 nm,...     

~1H and ~(13)C NMR studies of TTHA complexes with diamagnetic rare earth ions

TTHA complexes with diamagnetic rare earth ions (La3+, Y3+ and Lu3+) were studied by 1H and 13C NMR spectroscopy. A symmetric structural model was suggested for La(TTHA) complex and an asymmetric model for Y(TTHA) and Lu(TTHA) complexes. The complex formation was dependent on the pH value of the solution. The interactions of La(TTHA) with the additional metal ions (La3+, Y3+ and Ca2+) were relatively weak, but relatively strong for that of Lu(TTHA) with the additional Lu3+.     

~(13)C NMR SUBSTITUENT EFFECTS IN A SERIES OF 2-PHENYL BENZOTHIAZOLES

According to ~(13)C NMR determinations and analyses of 14 compounds of 2-phenyl benzothiazole, we have studied the substituent effects on aromatic hetero rings. The different substituents have effects on the charge densities in the molecules. We have also analyzed the structural factors of effects on ~nJ_(13C-1H). The perturbations of benzothiazole to benzene ring were studied by the method of comparison analysis. The substituent induced chemical shifts of benzothiazole were obtained. The experiential calculations of ~(13)C chemical shifts for aromatic carbons have been done, the calculated velues agreed with the experimental ones. The theoretical calculations for the compounds 2, 3, 9 have been made using the EHMO method (the Enlarged Hiickel Molecular Orbital Method). The relationships between the ~(13)C experimental chemical shifts and the total charge densities of the corresponding carbon atoms were obtained by the regression analysis. The correlation coefficient is—0.96.     

STUDY ON THE CHAIN-EXTENDING REACTION OF POLY (ETHYLENE TEREPHTHALATE) WITH 2, 2′-BIS (4H-3, 1-BENZOXAZIN-4-ONE)

2,2'-Bis (4H-3, 1-benzoxazin-4-one) (BBON) has been proved to be an effective chainextender for poly (ethylene terephthalate) (PET). In order to study the reaction mechanismand kinetics of chain-extending reaction, β-bishydroxyethylene terephthalate (BHET) wasselected as model compound. The NMR data, IR spectra and number average molecularweight (M_n) of the products obtained from the reaction of BBON and BHET verify thatBBON is a hydroxyl-reactive extender. The mechanism was discussed. Kinetics dataindicate that extending reaction is a second order reaction, and BBON has high reactivity.The activation energy (E_a) was measured.     

STUDIES ON ORGANOPHOSPHORUS COMPOUNDS XXXV——SUBSTITUENT EFFECT OF ORGANOPHOSPHORUS COMPOUNDS ON ~(31)P NMR SPECTROSCOPY

The linear relationship between the chemical shift of the resenant nucleus and the localvan der Waals steric energy calculated by molecular mechanics with MM2 force field wasextended to various organophosphorus compounds including alkyl-phosphates, -phosphonates,-phosphinates as well as -phosphine oxides. The conformational equilibria of a series of alkylO,O-1,3--propylene-and O, O-1,4-butylenephosphonates were studied by the molecular mechanicscalculations and the dynamic ~(31)P NMR spectroscopic method. As shown by these experimentaldata, the former existed in a chair form, and the latter in a twist boat form with an equatorialalkyl group in both configurations, either in gaseous state or in non-polar solvent.     

SEQUENCE STRUCTURE OF ETHYLENE-VINYL SUBSTITUTED COPOLYMER WITH ~(13)C NMR IV——CHLORINATED POLYETHYLENE

The substituent chemical shift (SCS) has been applied to the assignment of the ~(13)C NMRspectrum of chlorinated polyethylene (CPE). CPE of different chlorine contents has been em-ployed and their sequence structure discussed. The results show that characteristic of CPEwith medium chlorine content is the dichloroethane structure in molecular chain. SCS param-etets have been obtained from the ~(13)C NMR spectra. It was found that the effects of chlorinecontent and temperature on SCS are negligible, but the substituent parameter S_1 reduced by0.39 ppm when C_2Cl_4 was added to solvent ODCB.     

First synthesis of (±)-cedarmycin B

The synthesis of racemic cedarmycin B,an antibiotic from Streptomyces sp.TP-A0456 was achieved firstly fromγ- butyrolactone.The key step was a Barbier-type addition of 3-bromomethyl-5H-furan-2-one to formaldehyde mediated by zinc, which afforded the soleγ-addition product 4-hydroxymethyl-3-methylene-dihydrofuran-2-one.The final compound was confirmed by ~1H NMR,~(13)C NMR and HRMS.     

A Further Investigation into Intramolecular Process of Mg( Ⅱ )-, Sc( Ⅲ )-, Y( Ⅲ )-, In ( Ⅲ )-and Pb( Ⅲ )-CyDTA Complexes by the Method of Dynamic NMR

The intramolecular process of Mg ( Ⅱ ) - , Sc ( Ⅲ ) - , Y ( Ⅲ ) - , In(Ⅲ)-and Pb ( Ⅱ )-trans-1,2-cyclohexanediaminetetraacetic acid (CyDTA) complexes was studied by the method of proton dynamic NMR(DNMR). The top limit of. the experimental temperature range of deuterium oxide solutions was extended from 100℃ to 167 ℃ instead of the previous 100 ℃ by using sealed, thick-walled tubes to observe experimental phenomena further. It was found that another intramolecular process, i. e. B, R (Bonded State, Rotational State) conversion, exists in these complexes formed by polyaminepolycarboxylic ligands in addition to △,A conversion and nitrogen inversion. A quantitative treatment was proposed to estimate the relative populations of acetate groups in B and R states.     

Direct Observation of Various Al Sites in SAPO-34by ^27Al Multiquantum(MQ) Magic Angle Spinning (MAS)NMR

The elegant 2D multiquantum (MQ) MAS NMR has been applied to investigate the coordination of Al atoms in SAPO-34.The results show that the effects of the template and /or water on the coordination of Al atoms are significant,which lead to the formation of various Al species.Up to four kinds of Al species are distinctly resolved.     

~(29)Si MAS-NMR STUDIES ON DEALUMINATION OF MORDENITE

A series of different H-mordenites from acid leaching and steam calcination have beenmeasured with ~(29)Si NMR. Through analysis of these solid-state ~(29)Si NMR spectra, theresults related to dealumination process of mordenite are obtained. It is shown that mor-denite is combined by four kinds of non-equivalent Si (or Al) via oxygen bridges. The deal-umination order is T(1), T(2), T(4) and T(3). The dealuminated amount in the non-equivalentsites during different dealumination processes has also been discussed in detail.     

KINETICS AND MECHANISM OF PHOTOINDUCED POLYMERIZATION BY α,α-DIMETHOXY-α-PHENYL ACETOPHENONE

α,α-dimethoxy-α-Phenyl acetophenone (DMPA) is an efficient and thermally stable photoinitiator. Here its spectral characteristics in the transient state were shown. The transient species were identified as a benzoyl radical and a dimethoxyi benzyl radical that played a primary initiation role in polymerization. The kinetics and mechanism of the bulk polymerization of MMA were investigated. The exponent of DMPA concentration and k_p/k_1~(1/2) value were found to be 0.5 and 0.066 mol(-1/2)l~(1/2)s~(-1/2), respectively. The existence of oxygen led to obtain the polymer with higher molecular weight, which can be attributed to the occurrence of the subsequent polymerization induced by active polymer end group. In the photocrosslinking reaction, the dependence of DMPA content on initial rate has been found. A principal reason is that the sample contained higher percentage of DMPA has higher light-absorbed efficiency. In solid film, higher concentration of DMPA is permitted to be used because there is little excited state self-quenching effect in the rigid medium.     

Palladium(0)catalyzed reactions of propargylic carbonates and dialkyl cycloalkanone-α,α-dicarboxylates

Propargylic carbonates reacted with dialkyl cycloalkanone-α,α′-dicarboxylates under thecatalysis of Pd(0)complex to give bicyclic compounds in high yields.The two electron-withdrawinggroups at α and α′positions of cycloalkanone rings are essential for the annulation reaction.     

DMS AND ~(13)C NMR STUDIES ON THE COMPATIBILITY AND DYNAMICS OF LATEX BIDIRECTIONAL IPNS AND LATEX IPN OF PVAc/PBA

The compatibility and dynamics of latex bidirectional/nterpenetrating polymer networks (LBIPNs) and latex IPN(LIPN) of poly(vinyl acetate)(PVAc) and poly (butyl acrylate )(PBA) are investigated by means of dynamic mechanical spectroscopy (DMS) and nuclear magnetic resonance (NMR) techniques. The results of DMS show that the compatibility of the LBIPNs is much better than that of the corresponding LIPN and depends to, a large extent on the distribution of PVAc both in the core and in the shell. The results of NMR measurements indicate that the rotational correlation times of the side- groups of PBA in the LBIPN are longer than those in the LIPN. The relation between the ~(13)C linewidths of PBA and temperature is also discussed.     

Synthesis and Crystal Structure of Bis[O,O'-di(2-phenylethyl)dithiophosphato](α,α'-bipyridine)copper(Ⅱ)

A ternary adduct Cu[S2P(OCH2CH2Ph)2]2·bipy(bipy=α,α'-bipyridine) was syn-thesized and characterized by elemental analysis,IR and single-crystal X-ray diffraction.The crystal belongs to the triclinic system,space group P1 with a=10.2320(2),b=11.5249(3),c=18.0916(3),α=98.95(1),β =103.601(1),γ=91.272(2)°,V=2044.49(7)3,Z=2,Dc=1.453 g/cm3,T=153(2) K,C42H44CuN2O4P2S4,Mr=894.51,λ(MoKα)=0.71073,μ=0.86 mm-1,S=0.999,(△/σ)max=0.002,the final R=0.0243 and wR=0.0704.A total of 9221 unique reflections were collected,of which 8573 with Ⅰ 2σ(Ⅰ) were observed.The Cu(Ⅱ) atom is five-coordinated in a rather distorted trigonal bipyramidal geometry(τ value=0.537).The Cu-S distances range from 2.3491(4) to 2.4829(4) ,and the Cu-N distances are 1.9987(12) and 2.0584(11) ,respectively.An interesting feature of this adduct resides in its two-dimensional(2D) open framework constructing through hydrogen bonding and π-π interactions.     

Synthesis and Crystal Structure of Bis(nitrate)bis(N-n-octyl-α-pyrrolidone)uranyl (II)

1 INTRODUCTION Tri-butyl phosphate (TBP) has been widely used for the extraction reagent in Th-U fuel to separate uranium from thorium. However di-butyl phosphate (DBP) and butyl phosphate (MBP), the radiolytic products of TBP, exhibit some coordinated ability to the fission elements, such as Zr and Nb. The physical and chemical properties of amides and caprolactam are similar to those of TBP, and they selectively extract U(VI) and Th(VI). The principal advantages of amides an…     

Graphitic Carbon Nitride Microspheres Supportedα-FeO(OH)Hybrids for Visible Light Photodegradation of MO

Graphitic carbon nitride(g-C3N4)microspheres supported a-FeO(OH)hybrids[α-FeO(OH)/g-C3N4]were prepared by means of a self-assembly method in deionized water.By UV-visible diffiise reflectance spectroscopy,it has been confirmed thatα-FeO(OH)/g-C3N4 has a wider absorption range thanThe feature ofα-FeO(OH)/g-C3N4 can be attributed to the efficient separation of the electron-hole pairs with photoluminescence spectra.The degradation rate of methyl orange(MO)is up to 99%under the optimal conditions of 110 min,initial concentration of 30 mg/L,anα-FeO(OH)/g-C3N4 dosage of 15 mg as well as visible light.The mechanism for this photocatalytic reaction was proposed,with hydroxyl radicals being a major active catalytic species.     

Studies on Increasing the Activity of Selenium-Containing Abzyme (Ⅰ)——Synthesis, Characterization and Properties of Hapten and Antigen

The thiol group of glutathione (GSH) reacts specifically with 2.4-di-m-trochlorobenzene to give S-substituted dinitrophenyl glutathione (GSH-S-DNP);two carboxyl groups of GSH-S-DNP were further esterified by n-butanol to produce the hapten,multisubstrate analog GSH-S-DNP Butyl Ester (GSH-S-DNP BE).The primary structure of the hapten was characterized by the free ammo group analysis,1H NMR,IR determinations and the elemental analysis.The hapten was then conjugated to bovine serum albumin (BSA) in the presence of glutaraldehyde.The reaction mixture was purified by Ultrogel AcA54 coluni chromatography to give the antigen.On an average,25 haptens were bound to each BSA molecule.Electrophoresis analysis showed that the average molecular weight of the antigen was 87 KD.CD spectrum showed that the α-helix content of the antigen increased.     

Phase Structures of Nascent Polyethylene Powder Studied by Wideline Proton NMR

The wideline proton NMR spectra of polyethylene powder samples were analyzed in terms of contributions from three components： （1） a rigid part with immobile chains, （2） a soft region with liquid-like character which produces a Lorentzian contribution to the spectrum, and （3） an intermediate region in which the rotation of methylene groups about C-C bonds is partially hindered. The relative mass fractions as well as chain mobilities varied greatly among samples produced by different polymerization techniques. The NMR crystallinity agreed well with that estimated by WAXD and was much higher than DSC crystallinity, indicating an inclusion of the contribution from a crystalline-amorphous interphase. The crystalline defects in the rigid part could be significantly affected by processing parameters when employing the same type of polymerization technique. The intermediate region in the NMR spectra was analyzed according to the comparison between bimodal high density polyethylene and corresponding linear unimodal one. It was found that the mass fraction of the NMR interphase could be an indication of the percentage of tie molecules between crystalline lamellae and thus may significantly affect the mechanical properties of polymeric material.