A stepwise-synthesis method was used to immobilize tetrachloro-tetramethyl porphyrins in the supercages of NaCoX molecular sieve. The immobilized porphyrin was characterized by means of UV-Vis, IR, DTA, SEM and EPR. A comparision was made for the activities among tetrachloro-tetramethyl porphyrins, its cobalt(Ⅱ) complex, NaCoX molecular sieve and the immobilized porphyrin as catalysts in the oxidation reaction of styrene and p-cresol. The stability and catalytic capability of the metalloporphyrin is increased after the combination of porphyrin with molecular sieve. In addition, this new type of catalyst tetrachloro tetramethyl porphyrin immobilized in the supercages of NaCoX molecular sieve not only possesses the advantages of both porphyrin and molecular sieve, but also makes up for their respective deficiencies. The experimental results confirmed that both the stability and catalytic capability of metalloporphyrin immobilized in the supercages of molecular sieve are increased.
The catalytic activities of some heteropolyacids(HPAs) in synthesizing butyl-acrylate are reported. It has been demonstrated that 12-tungstophosphoric acid is the most effective catalyst among more than 20 HPA(salts). Various factors concerned in this reaction have been investigated. The optimum conditions have been found, that is, the molar ratio of alcohol to acid is 1.2∶1.0 , the catalyst concentration 1%(mass fraction), the reaction time 2 h, the temperature 98—124 ℃ and a certain amount of polymerization inhibitor exists.
MnO2-doped PbTiO3 ceramics was prepared by means of sol-gel method, its density and some electric properties were investigated. The results showed that it was feasible to prepare multicomponent PbTiO3 sol-gel series with the aid of sol-gel method, the obtained MnO2-doped PbTiO3 ceramics showed a high-purity, uniform component, better dense structure, hardly crack, and had good dielectric, piezoelectric, ferroelectric and pyroelectric properties.
The effect of catalysts P-2.00-Ni(Nickel boride) and P-2.00-Ni-M(M: Co, Fe, Cu, Sn), prepared by adopting a modified recipe, on the chemoselective hydrogenation of carbon-carbon double bonds in α,β- unsaturated ketones, and the activity of catalysts P 1.80 Ni, P-2.00-Ni or P-1.80(2 00)-Ni-M(M: Pd, Co, Cu) in the selective hydrogenation of carbon-carbon double bonds in α,β-unsaturated carboxylic esters, were investigated systematically. According to the experimental results, the selectivities of these catalysts toward the hydrogenation of the carbon carbon double bonds of α,β-unsaturated keones or α,β-unsaturated carboxylic esters are 96%—100% or 100%, respectively.
The cyclizations of alkyl 2-dimethoxyacetyl and 2-ethoxalyl-4-oxopentanoates were only effected by means of pyrrolidine with the formation of appropriately substituted 1-pyrrolidin-1-ylcyclopentadienes.
(R)-N-(β-Trichlorogermyl propionyl)thiazolidine-2-thione-4-carboxylic methyl ether(1) and its sesquioxide(2) were synthesized. The crystal structure of 1 was determined by means of X-ray diffraction analysis, which shown that the >C=O and >C=S groups are located in the opposite sides of C(4)—N—C(3) bond with trans configuration. The electronic structures and optimized configurations of compounds 1 and 2 were studied with MNDO method.
Inactivity guided experiments, awater soluble polysaccharide PPQ5-2, which shows lymphocite stimulation and interleukin induction activieties, from Panax quinquefolium L. was isolated and characterized. It is composed of D-arabinose and D-galactose in amolar ratio of 1∶1.1 in alditol acetate derivatives analyzed by means of GC. Galacturonic acid was detected with GC. The elementary analysis showed about 8% of protein in it. The molecular weight is about 21 000 determined by matrix-assisted laser desorption/ionization mass spectrometry.
The dependence of the differential capacitance of polypyrrole doped with several typical dopants on potential is presented, which shows that the differential capacitance varies with the potential, the doped polypyrroles with electroactive ions give the largest capacitance near their formal potentials, which is attributed to the mutual media for electron transfer between polypyrrole and electroactive dopants. The existence of two conducting phases was observed in the complex capacitance plots. The electroactive anions act as an intra-conducting-phase medium for electron transfer, the electroactive cations act as an inter-conducting phase medium for electron transfer. The mutual media between polypyrrole and redox dopants lead to the increase of the discharging time.
The reaction of hydrogen peroxide with cytochrome c makes them coupled to lead to the hydroxylation of 4-nitrophenol. In situ electrochemical probe was used to detect the hydroxylation of 4-nitrophenol, which can avoid the tedious extraction procedure, the loss of the active species and the interference of some colored substances in the detection of 4-nitrocatechol by spectroscopic method. The hydroxyl radical scavengers mannitol and sodium benzoate did not eliminate hydroxylation, but the inhibitory effect of uric acid on the hydroxylation lead to the formation of the ferryl species of the protein during the reaction. These studies suggest that the electrochemical probe might efficiently detect the trace 4-nitrocatechol from the onset of the hydroxylation reaction and thus provides a more sensitive tool.
Native glycopeptides are suitable to FAB mass spectrometric analysis due to their high polarity, low volatility and large molecular size. The deficiency in the FAB spectra of glycopeptides is the limited number of peaks and the low abundances of fragments. In order to obtain the information of carbohydrate sequence the permethylation of carbohydrate, a well known method, is recommended here. The L-β-aspartamido-carbohydrate from chicken egg albumin was chosen as the model compound of glycopeptides. Our experiments showed obvious carbohydrate-sequence in the spectra of permethylated aspartamido carbohydrates. The key conditions to perform the method are the methylation reagent and purification process for the permethylated derivatives.
FTIR, UV-visible , fluorescence spectra and calculation of CPK model indicated that poly(1-naphthol) synthesized and assembled by horseradish peroxidase(HRP) in aqueous micelle was constructed with orderly helical conformation, which was the lowest energy conformation of the polymer under this condition and resulted in an advanced π-conjugated system.
The low energy collision induced dissociation, linked scan techniques and isotopic labeling experiment were used to investigate the unimolecular fragmentation of protonated N-hydroxyphthalimide under electron impact and chemical ionization conditions. It was found that this compound shows an unusual reactivity towards protonation. Two possible sites of protonation have been proposed to explain the corresponding fragmentation processes, one is that the protonation takes place on the oxygen atom of hydroxyl group, resulting in the loss of water and the other is the formation of an intermediary proton-bound complex in the fragmentation process, giving rise to the fragment ions of m/z 133 and m/z 135. The results show both cases are coexistence in the fragmentations of protonated N-hydroxyphthalimide, and the unimolecular fragmentation pathways are available.
Zn2Al layered double hydroxide pillared with Dawson polyoxometalates, P2W17ZO618-(Z=Mn2+, Co 2+, Ni2+, Cu2+, Zn2+) was prepared. A basal space of ca. 16 nm indicates the intercalated Dawson ions to be oriented with their C2 axis perpendicular to the double hydroxide layers(with the exception of P2W17Zn-LDH). The IR and13P MASNMR spectral reveal that the Dawson ions retain their integrity in the interlayer space of LDH. A preliminary study shows that these compounds are highly active catalysts for the oxidation of cyclohexene with molecular oxygen.
C2 and LaC2+ were studied using Hartree Fock(HF), B3LYP (Becke 3-paremeter-Lee-Yang-Parr) density functional method, second order M φller-Plesset perturbation(MP2) and coupled cluster singles and doubles with non-iterative triples(CCSD(T)) methods. The basis set employed was LANL1DZ. Geometries, vibrational frequencies and other quantities were reported. The results showed that for C2, all the methods performed well for low spin state(singlet), while only HF and B3LYP remained so for high spin state(triplet). For LaC2+, four isomers were presented and fully optimized. The results suggested that linear isomers with C∞v and D∞h symmetries were predicted to be saddle points on the energy surface for all the methods, while for isomers with C2v and Cs symmetries, they were local minima except C2v at B3LYP level, and were isoenergetic at HF, MP2 and CCSD(T) levels, near isoenergetic at B3LYP level. From the differences between HOMO and LUMO, it is also known that the isomers with C2v and Cs symmetries offer the largest values and therefore correspond to the most stable structure. ForLa—C bond lengths, B3LYP gives the shortest, the order is B3LYP<HF<MP2<CCSD(T) for all the methods.
Lanthanum-modified lead titanate(PLT14) ultrafine particles were synthesized by means of stearic acid gel method. The structure of the samples was characterized using X-ray diffraction(XRD) and TEM. The crystal graphic parameters of the samples were calculated. The Raman spectra of PLT14 powders at a high pressure as well as a high temperature reveal that the phase transition pressure or temperature shifts to a lower pressure or temperature with the decrease of grain size.
The geometry and binding interaction of M+CO2(M represents the first row transition metals) were studied using ab initio methods. In some cases the frequency calculations and basis set superposition error corrections were included. For all the complexes under the study, the linear structures were found to be the equilibrium structure. The distances of M+—O in R(M+—O) in which M has 4s electrons are obvious longer than those in which M has no 4s electrons, and from Sc to Zn the change trend is decreased, accompanied with some oscillation. The binding energy has an opposite change trend to that of the R(M+—O). Linear M+CO2 has the same spin as M+, while T-shape structures may have different spins. The static electronic interaction was found to be about 80% of the total binding energy.
Two kinds of 1,4-anhydroribose derivatives, 1,4-anhydro 2,3-O-benzylidene-α-D-ribopyranose （ABRP） and 1,4-anhydro 2,3-O-isopropylidene α D ribopyranose （AIRP） were prepared from D-ribose. The ring-opening copolymerizations of ABRP and AIRP in various feed ratios were carried out with SbCl5 and BF3OEt2 as catalyst at low temperatures. The copolymer structure was characterized by means of 1H,13C NMR spectroscopy and specific rotation. When SbCl5 was used as catalyst, the copolymer obtained had completely 1,4-β-pyranosidic structure, i.e., cellulose type structure. However, when BF3OEt2 was used as catalyst, the copolymer had a mixed structure of furanosidic and pyranosidic units.
A new series of liquid crystals of bis[4-(p-phenoxy)-phenylbenzoate]-alkyldicarboxylate which contain two rigid groups connected by a flexible spacer was synthesized. These liquid crystals show nematic phase and were found to show odd even effect in isotropization temperature and entropy change.
By means of electron paramagnetic resonance(EPR), chemistry luminescence and fluorescent spectroscopy, the free radical, superoxide dismutase and water soluble lipid peroxide in tears of normal eyes(150 eyes, 100 cases), Moorens ulcer(9 eyes), coreal grafts rejection(16 eyes) were studied. The results showed that the spin density of the free radical was 3.6(±0.58)×1012 spins/mL tear, the content of the superoxide dismutase(SOD) was 3.84(±1.45) ng/mL tear, the opposite fluorescent density of the water soluble lipid peroxide was 12.912(±1.691) U/mL tear in normal tears. The normal values are 2.5—4.8×1012 spins/mL tear for free radical, 2.39—5.29 ng/mL tear for SOD, 9.598—16.225 U/mL tear for water soluble lipid peroxide. There are significant differences in different eyes, different sexes and different ages. The free radical and lipid peroxide are higher obviously in the tears of patients with Moorens ulcer and rejected corneal grafts, compared with those of the normal control subjects(P<0.01), SOD is lower evidently(P<0.01). The above fact shows the pathogenic mechanism of Moorens ulcer and keractoplasty rejection is significantly related to toxicities injuring effect of the free radical. These results have provided important experimental data for studying lacrimalogy and new methods for clinical diagnosis and treatrment.