MECHANISM-TRANSFORMATION SYNTHESIS AND CHARACTERIZATION OF POLY(STYRENE-b-2-ETHYL-2-OXAZOLINE) DIBLOCK COPOLYMER*

By mechanism-transformation (anionic→ cationic) poly(styrene- b-2-ethyl -2-oxazoline) diblockcopolymer, PS-b-PEOx, was synthesized in two steps. The first step is the polymerization of styrene blockcapped with ethylene oxide and its tosylation; the second step is the cationic ring-opening polymerization of2-ethyl-2-oxazoline. The products were thoroughly characterized by various methods, such as ~1H-NMR, IR,DMA, TEM and SAXS. The results show that the copolymer obtained possesses high molecular weight andnarrow molecular weight distribution.     

A dynamical Lie algebraic mehtod for quantum reactive scattering

Ｒａｐｉｄｐｒｏｇｒｅｓｓｉｎｔｈｅｔｈｅｏｒｙｏｆｑｕａｎｔｕｍｒｅａｃｔｉｖｅｓｃａｔｔｅｒｉｎｇｈａｓｂｅｅｎｍａｄｅｉｎｔｈｅｐａｓｔｆｅｗｙｅａｒｓ.Ａｓａｒｅｓｕｌｔｏｆｔｈｅｐｒｏｇｒｅｓｓｏｎｅｃａｎｎｏｗｃａｌｃｕｌａｔｅｅｘａｃｔｓｔａｔｅ＿ｔｏｓｔａｔｅｒｅａｃｔｉｏｎｃｒｏｓｓｓｅｃｔｉｏｎｓｆｏｒａｆｅｗｆｕｎｄａｍｅｎｔａｌｒｅａｃｔｉｏｎｓ.Ａｍｏｎｇｖａｒｉｏｕｓｆｏｒｍｕｌａｔｉｏｎｓｏｆｔｈｅｔｈｅｏｒｅｔｉｃａｌａｐｐｒｏａｃｈ,ｔｈｅＳｍａｔｒｉｘＫｏｈｎｖ…     

DNA-modified electrodes (VII)

Two kinds of DNA-modified electrodes were prepared by covalent and adsorptive immobilization of DNA onto self-assembled monolayers of 2, 2’-dithiodiethanol on gold electrodes and characterized by cyclic voltammetry, X-ray photoelectron spectroscopy and scanning tunneling microscopy. The results suggest that the methods are satisfactory for the immobilization of DNA on electrodes. Project supported by the National Natural Science Foundation of China (Grant Nos. 39370213; 39770220; 29773034), State Key Laboratory for Physical Chemistry of Solid Surfaces (Xiamen University), and Natural Science Foundation of Hubei Province (Grant NO. 96J037).     

Quantum dynamics of dissociative adsorption of H2 and D2: The time-dependent wave packet method

A time-dependent quantum wave packet method was used to study the dynamics of dissociative adsorption of H₂ and D₂ on a flat and static surface. The molecule-surface interaction is described using a modified London-Eyring-Polanyi-Sato (LEPS) type potential for the H₂/Ni(100) system. The three-dimensional (3-D) dissociation probabilities were calculated for different initial rovibrational states as a function of initial incident energies. Our results show that the dissociation of the diatomic rotational states whose quantum numbers satisfyj+m = odd is forbidden at low energies for the homonuclear H_z and D₂ due to the selection rule. The effect of the rotational orientation of diatoms on adsorption predicts that the in-plane rotation (m = j) is more favorable for dissociation than the out-of-plane rotation (m = 0). Enhanced dissociation for vibrationally excited molecules and the significant enhancement of the dissociation probability of H2 when compared to D₂ were explained reasonably in terms of quantum mechanical zero-point energies, the tunneling effect and the reflection from an activation barrier. Project supported by the National Natural Science Foundation of China (Grant No. 19694033) and partially by the Science Foundation for Overseas Chinese Scholars and Students, administered by the State Education Commission of China (Grant No. 1992), by the State Key Laboratory of Theoretical and Computational Chemistry of Jilin University at Changchun (Grant No. 98011, and by the Natural Science Foundation of Shandong Province (Grant No. Y96B03022)     

A Novel Initiator Containing Alkyne Group for the Polymerization of 2-Ethyl-2-oxazoline

A novel trifunctional initiator with one alkyne and two trifluoromethanesulfonate moieties was synthesized from a protected alcohol 5-hydroxyl-2-phenyl-1, 3-dioxane. The alkyne functionalized intermediate with two protected alcohol groups was synthesized by reacting with propargyl bromide. The alcohol groups were cleaved using a mixture of tetrahydrofuran and hydrochloric acid aqueous solution. In the last step the initiator was synthesized using triflic anhydride in carbon tetrachloride. The initiator was characterized by ¹H NMR and used for the polymerization of 2-ethyl-2-oxazoline which gives polymers with narrow distribution. For comparison a similar initiator with two tosylates was prepared and used for the polymerization of the monomer 2-ethyl-2-oxazoline, the resulting product has a wide molecular weight distribution and most of the initiator remains unreacted after 24 h which may be due to the steric hindrance between the two tosylate groups. To further explore the steric hindrance phenomenon, a linear tosylate initiator was synthesized, but still some of the initiator remains unreacted, illustrating that both steric hindrance and electrophilic balance affect the efficiency of the cationic ring-opening polymerization. All of the polymers were characterized in detail by using ¹H NMR, matrix-assisted laser desorption/ionization time-of-flight mass spectroscopy, and size exclusion chromatography to confirm the purity and distribution of the polymers.     

Preparation and properties of poly(alkyl vinyl ether-2-ethyl-2-oxazoline) diblock copolymers

A method for the synthesis of well-defined poly(alkyl vinyl ether–2-ethyl-2-oxazoline) diblock copolymers with hydrolytically stable block linkages has been developed. Monofunctional poly(alkyl vinyl ether) oligomers with nearly Poisson molecular weight distributions were prepared via a living cationic polymerization method using chloroethyl vinyl ether together with HI/ZnI₂ as the initiating system and lithium borohydride as the termination reagent. Using the resultant chloroethyl ether functional oligomers in combination with sodium iodide as macroinitiators, 2-ethyl-2-oxazoline was polymerized in chlorobenzene/NMP to afford diblock copolymers. A series of poly(methyl vinyl ether–2-ethyl-2-oxazoline) diblock materials were found to have polydispersities of ≈ 1.3–1.4 and are microphase separated as indicated by two T_g's in their DSC thermograms. These copolymers are presently being used as model materials to study fundamental parameters important for steric stabilization of dispersions in polar media. © 1993 John Wiley & Sons, Inc.     

Synthesis and characterization of thermally crosslinked polyimide with second-order nonlinear optical chromophore

Ｉｎｃｏｍｐａｒｉｓｏｎｗｉｔｈｉｎｏｒｇａｎｉｃｎｏｎｌｉｎｅａｒｏｐｔｉｃ(ＮＬＯ)ｍａｔｅｒｉａｌｓ,ｏｒｇａｎｉｃｐｏｌｙｍｅｒｉｃＮＬＯｍａｔｅｒｉａｌｓｈａｖｅｍａｎｙａｄｖａｎｔａｇｅｓ,ｓｕｃｈａｓｌｉａｂｌｅｍｏｌｅｃｕｌａｒｄｅｓｉｇｎａｎｄｏｐｔｉｍｉｚａｔｉｏｎ,ｌａｒｇｅｒｎｏｎｒｅｓｏｎａｎｃｅＮＬＯｃｏｅｆｆｉｃｉｅｎｃｙ,ｌｏｗｅｒｄｉｅｌｅｃｔｒｉｃｃｏｎｓｔａｎｔ,ｇｏｏｄｗｏｒｋｉｎｇａｂｉｌｉｔｙ,ｏｐｔｉｃａｌｔｒａｎｓｐａｒｅｎｃｙａｎｄｒｅｓｉｓｔａｎｃｅａ…     

可见光催化有氧脱氢合成2,3-二氢-4-吡啶酮与4-喹诺酮

报道了一种可见光促进4-哌啶酮及2,3-二氢-4-喹诺酮的有氧脱氢化方法.研究中通过使用一种二腈基哌嗪化合物（dicyanopyrazine-derived chromophore,DPZ）为光催化剂,能够以令人满意的分离产率（最高75%）分别合成出2,3-二氢-4-吡啶酮与4-喹诺酮.本反应为这两类重要含氮杂环化合物提供了一种直接的、可持续的以及高原子经济性的合成途径.     

Design, syntheses and biological activity of novel ALS inhibitors (IX)

Quantitative structure-activity relationships for herbicidal activity against rape of sulfonylurea and triazolopyrimidine-2-sulfonamide derivatives were examined three-dimensionally using comparative molecular field analysis (CoMFA). The CoMFA results show that the slopes in steric and electrostatic fields around the molecule were significant for both series in governing the potency variations in herbicidal activity. Based upon the successful superposition between the two series, the herbicidal activity was analyzable with a single equation for the combined set of compounds, which suggested that the two different series of compounds have a common region of the receptor site. Project supported by the National Natural Science Foundation of China (Grant No. 29832050), the Special Key Fund of Natural Science of Tianjin (Grant No. 983801011) and the Doctoral Fund of the Education Ministry of China.     

聚乙烯丙烯酸与聚(2-乙基-2-噁唑啉)接枝共聚物的合成及表征

选用聚乙烯 丙烯酸 (EAA)为接枝母体 ,首先摸索出 2 乙基 2 唑啉阳离子开环聚合的规律 ,得到高转化率端基为活性离子的聚 ( 2 乙基 2 唑啉 ) (PEOX) ,再与EAA羟基侧基进行接枝反应 ,考察了开环聚合条件及接枝反应条件对接枝率的影响 ,在一定的条件下得到了接枝率 >2 5%的聚乙烯 丙烯酸与聚 ( 2 乙基 2 唑啉 )的接枝共聚物 (EAA g PEOX) .该接枝物用于聚对苯二甲酸丁二醇酯 /聚丙烯 (PBT/PP)共混体系中作相容剂 ,可提高两者的相容性 .     

聚乙烯—丙烯酸与聚（2—乙基—2—恶唑啉）接枝共聚物的合成及表征

选用聚乙烯－丙烯酸（ＥＡＡ）为接枝母体,首先摸索出２－乙基－２－恶唑啉阳离子开环聚合的规律,得到高转化率端基为活性翁离子的聚（２－乙基－２－恶唑啉）（ＰＥＯＸ）,再与ＥＡＡ羟基侧基进行接枝反应,考察了开环聚合条件及接枝反应条件对接枝率的影响,在一定的条件下得到了接枝率〉２５％的聚乙烯－丙烯酸与聚（２－乙基－２－恶唑啉）的接枝共聚物（ＥＡＡ－ｇ－ＰＥＯＸ）。该接枝物用于聚对苯二甲酸丁醇酯／聚丙烯（Ｐ     

Electronic spectroscopy and photochromic mechanism of bis-Schiff bases, N, N′-bis(2-hydroxy-l-naphthylidene)-l, 4-phenyldiamine

The steady state and transient state absorption spectra and fluorescence spectra of N, Ń-bis(2-hydroxy-1-naphthylidene)-1, 4-phenyldiamine (BNP) in cyclohexane and acetonitrile were determined. The photochromic mechanism was discussed. In nonpolar solvents, BNP exists mainly in the enol form and has the absorption maximum in the UV region. In polar solvents, however, both the enol and proton transfer tautomer are formed, but the former is the main one. Fluorescence emissions result from the excited state of proton transfer product. Project supported by the National Natural Science Foundation of China and the Foundation of Chinese Academy of Sciences.     

Bis-macromonomers of 2-alkyl-2-oxazolines–synthesis and polymerization

Poly(2-alkyl-2-oxazoline)s having an acrylate group at both chain ends were synthesized by terminating living bifunctional poly(2-methyl-2-oxazoline) or poly(2-ethyl-2-oxazoline) with acrylic acid. These macromonomers have been polymerized to the corresponding polyoxazoline networks. Thermal as well as UV-initiated free radical polymerization were applied and the influence of the polymerization conditions and molecular weight of the prepolymer used on the properties of the networks were investigated. Both methods of polymerization produced high fractions of soluble material, probably due to the low concentration of the acrylate end groups.     

Multiphoton excitation of an ammonia molecule in laser fields

The multiphoton excitation of NH3 in laser fields is discussed using the second quantization and unitary transformations.The stretch-vibration energy spectrum obtained from an optimized Hamiltonian is in good agreement with that of experiments.The changes in transition probabilities with the frequencies of laser fields and the lime-dependent transition probabilities at a field intensity of 1.1×10-8 W/cm2 are presented.Finally,the energy absorption is calculated.     

Quantum dynamics of dissociative adsorption of H2 on Ni(100) using the dynamical Lie algebraic method

A dynamical Lie algebraic method has been applied to treating the quantum dynamics of dissociative adsorption of H₂ on a static flat metal surface. An LEPS potential energy surface has been used to describe the interaction of H₂ with Ni(100) surface. The dependence of the initial state-selected dissociation probability was obtained analytically on the initial kinetic energy and time. A comparison with other theoretical calculations and experiments is made. The results show that the method can be effectively used to describe the dynamics of reactive gas-sdace scattering. Project supported by the National Natural Science Foundation of China (Grant No. 19694033) and partially by the State Key Laboratory of Theoretical and Computational Chemistry of Jilin University (Grant No. 9801).     

Synthesis and magnetic resonance of new heteropolynuclear Ln(III)-Cu(II) complexes with noncyclic polyether Schiff base

Ｎｏｎｃｙｃｌｉｃｐｏｌｙｅｔｈｅｒｓｈａｖｅａｔｔｒａｃｔｅｄｍｏｒｅａｎｄｍｏｒｅａｔｔｅｎｔｉｏｎｆｏｒｔｈｅｉｒｎｏｎｅｘｐｅｎｓｉｖｅ,ｌｅｓｓｔｏｘｉｃｉｔｙａｎｄｓｏｏｎ.Ｔｈｅｙｈａｖｅｓｏｍｅｐｒｏｍｉｓｉｎｇａｐｐｌｉｃａｔｉｏｎｓｉｎｓｏｌｖｅｎｔｅｘｔｒａｃｔｉｏｎａｎｄｅｎｒｉｃｈｍｅｎｔｏｆｍｅｔａｌｉｏｎｓａｓｗｅｌｌａｓｉｎｔｈｅｉｏｎｓｅｌｅｃｔｉｖｅｅｌｅｃｔｒｏｄｅ,ｅｔｃ.[1].ＮｏｎｃｙｃｌｉｃｐｏｌｙｅｔｈｅｒＳｃｈｉｆｆｂａｓｅｉｓｏｎｅｏｆｐｏｌｙｄｅｎ…     

In situ spectroelectrochemical behaviour of nanocrystalline TiO2 thin films electrode fabricated by pulsed laser deposition

Nanocrystalline titanium oxide thin films have been successfully deposited on IT0 coated glass by pulsed laser ablation of metallic Ti target in 0₃/0₂ ambient gases. The intercalation of Li ions in the anatase TiO₂ film electrode is examined by cyclic voltammetry. The electrochromic behaviour of TiO₂ electrode is investigated byin-situ visible transmittance measurement, and two absorption bands at 420 and 650 nm are observed. The absorption falling and rising in color changing with excellent revisibility is relative to the insertion and deintercalation processes of Li ion. These results suggest that nanocrystalline titanium oxide films fabricated by pulsed laser deposition exhibit excellent spectroelectrochemical property. Project supported by the National Natural Science Foundation of China (Grant No. 29783001) and State Key Laboratory for Physical Chemistry of Solid Surface of Xiamen University (1997).     

[trans-en2Os (ŋ-H2)]2 + as an1H NMR probe for the coordination of some anticancer metal complexes to deoxyguanotide

The molecular hydrogen complex of osmium, [trans-en₂Os (ŋ-H₂)]²⁺ (en, entlylendediamine) is a new¹H NMR recognition probe for biomolecules. By using this probe, the coordination between deoxyguanylic acid (dGMP) and four metal anticancer complexes, titanocene dichloride, (C₂H₅)₂SnCl₂(phen). (C₂H₅)₂SnCl₂ and cisplatin are studied in D₂O under the condition near the physiological one. The results show that the former three complexes mainly and strongly coordinate with the phosphate oxygen of dGMP, while cisplatin mainly coordinates with N(7) of dGMP. Project supported by the National Natural Science Foundation of China, the Natural Science Foundation of Shanxi Province and the Youth Science Foundation of Shanxi Province.     

Synthesis and catalytic activity of novel heteronuclear Ln (III) -Cu(II) complexes with noncyclic polyether-amino acid Schiff base

A series of novel heteronuclear Ln(III)-CU(II) complexes with noncyclic polyether-amino acid Schiff base were synthesized. The general formula is (LnCu₂(H₂TALY) (NO₃)₅] (NO₃)₂·nH₂O (Ln= La, Nd, Sm, Gd,n = 4; Ln = Yb, Y,n = 3), where H₂TALY = tetraglycol aldehyde bis-lysine Schiff base. It is the first time to report the synthetic method for this new Cu(II) complexes and Ln(III)-Cu(II) heteronuclear complexes. The complexes were characterized by elemental analysis, IR spectra. TG-DTA, magnetic susceptibility, and especially by a 500 MHz NMR spectrometer for 2D-COSY NMR. Coordination mechanism and structures of complexes have been suggested as well. Of particular interest is the potential that the novel complexes obtained may be used as a catalyst. which prompted us to investigate them. It shows 100% conversion with the viscosity-average molecular weight 120 000 for the polymerization of methyl methacrylate (MMA) without addition of any cocatalyst. Furthermore, the complexes with such aliphatic Schiff bases can be used as a good catalyst, which has been confirmed and discussed here. They may be a new kind of catalyst system with the above speciality. Project supported by the National Natural Science Foundation of China (Grant No. 29671026) and Natural Science Foundation of Zhejiang Province (Grant No. 296062) and the Laboratory of MRAMP (Grant No. 971502).