Synthesis and photodegradation of poly[2,5-bis(dimethylsilyl)thiophene]

Summary Poly[2,5-bis(dimethylsilyl)thiophene] (I), a copolymer with alternating thiophene and disilyl units, has been prepared by the Wurtz coupling of 2,5-bis(dimethylchlorosilyl)thiophene (IV) with sodium metal in toluene. I has been characterized by ¹H, ¹³C, and ²⁹Si NMR, IR, UV, GPC, TGA and elemental analysis. The photolysis of I in benzene/methanol solution results in degradation of the polymer. The structure of the photoproducts and possible mechanisms for their formation are discussed.     

Synthesis and photodegradation of poly[1,4-bis(dimethylsilyl)naphthalene]

Summary Poly[1,4-bis(dimethylsilyl)naphthalene](I), a copolymer with alternating 1,4-naphthalene and disilyl units, has been prepared by the Wurtz coupling of 1,4-bis(dimethylchlorosilyl) naphthalene (II) or 1,4-bis(dimethylfluorosilyl)naphthalene (III) with sodium metal dispersion in toluene. The molecular weight distribution of I prepared from III is significantly higher than when I is prepared from II. I has been characterized by ¹H, ¹³C and ²⁹Si NMR, IR, UV, GPC, TGA and elemental analysis. Photolysis of I in benzene/methanol solution results in rapid degradation of I.     

Polymerization of [2,5-bis(trifluoromethyl)phenyl]acetylene and polymer properties

Summary [2,5-Bis(trifluoromethyl)phenyl]acetylene [BTFPA; HCCC₆H₃-2, 5-(CF₃)₂]polymerized with W, Mo, and Nb catalysts to produce methanol-insoluble polymers in high yields. The poly(BTFPA) produced by the W(CO)₆-based catalyst at 30 °C was soluble in p-(CF₃)₂C₆H₄, and had relatively high molecular weight ([]=0.352 dL/g in p-(CF₃)₂C₆H₄). The main chain of the polymer was composed of alternating double bonds, and the polymer was a dark brown solid. The temperature at which the weight loss of the polymer started was higher than 300 °C. The polymerization behavior and polymer properties for BTFPA are compared with those for phenylacetylene and [o-(trifluoromethyl)phenyl]acetylene.     

Synthesis and properties of new poly(amide-imide)s based on 2,5-bis(trimellitimido)toluene

Summary A series of new aromatic poly(amide-imide)s were synthesized by the triphenyl phosphite activated polycondensation of the diimide-diacid, 2,5-bis(trimellitimido)toluene (I) with various aromatic diamines. The poly(amide-imide)s had inherent viscosities of 0.69–1.89 dL/g. Most of the resulting polymers showed an amorphous nature and were readily soluble in a variety of organic solvents. Transparent, flexible, and tough films of these polymers could be cast from DMAc or NMP solutions. Their cast films had tensile strengths ranging from 76 to 112 MPa, elongations at break from 8 to 31%, and initial moduli from 2.20 to 2.99 GPa. The glass transition temperatures of these polymers were in the range of 253–328°C. Received: 25 September 1998/Revised version: 2 December 1998/Accepted: 8 December 1998     

Synthesis and two-photon absorption properties of 2,5-bis[4-(2-arylvinyl)phenyl]-1,3,4-oxadiazoles

Two symmetrical 2,5-bis[4-(2-arylvinyl)phenyl]-1,3,4-oxadiazoles that exhibit strong two-photon absorption and enhanced two-photon excited fluorescence were designed and synthesized based on “push-core-pull-core-push” molecules built from embedding electron-transporting 1,3,4-oxadiazole in aromatic conjugated system through Wittig–Horner reaction. Pumped by nanosecond laser at 800 nm, strong up-conversion emissions with the central wavelength at 507 nm (green) of 2,5-bis[4-(2-N,N-diphenylaminostyryl)phenyl]-1,3,4-oxadiazole and 475 nm (blue) of 2,5-bis[4-{2-(3-N-ethylcarbazolyl)vinyl}phenyl]-1,3,4-oxadiazole in the solution of CHCl₃ have been observed. Their two-photon absorption cross-sections obtained by nonlinear transmission method are 107 × 10⁻⁴⁸ cm⁴ s photon⁻¹ and 66 × 10⁻⁴⁸ cm⁴ s photon⁻¹. A very effective energy transfer from the excited terminal units to the π-conjugated bridging units of the 2,5-bis[4-(2-arylvinyl)phenyl]-1,3,4-oxadiazoles is the dominant contribution to the two-photon absorption.     

Synthesis and characterization of 2,5-bis[4-(2-arylvinyl) phenyl]-1,3,4-oxadiazoles with two-photon fluorescence properties

Four novel 2,5-bis[4-(2-arylvinyl)phenyl]-1,3,4-oxadiazoles that exhibit strong two-photon absorption and enhanced two-photon excited fluorescence were designed and synthesized based on “push-core-pull-core-push” molecules built from embedding electron-transporting 1,3,4-oxadiazole in aromatic conjugated system through Wittig-Horner reaction. Their chemical structures were determined to show trans-vinylene character according to infrared (IR) and ¹H nuclear magnetic resonance (NMR) spectra. A very effective energy transfer from the excited units to the π-conjugated bridging unit can enhance the two-photon absorption and two-photon fluorescence. __________ Translated from Journal of Southeast University (Natural Science Edition), 2006, 36(5): 795–798 [译自: 东南大学学报 (自然科学版)]     

Synthesis and characterization of new organo-soluble poly(amide-imide)s based on 1,4-bis(trimellitimido)-2,5-dimethylbenzene

Summary A series of new aromatic poly(amide-imide)s were synthesized by the triphenyl phosphite activated polycondensation of the diimide-diacid, 1,4-bis(trimellitimido)-2,5-dimethylbenzene (I), with various aromatic diamines. The poly(amide-imide)s had inherent viscosities of 1.13–2.22 dL/g. Most of the resulting polymers showed an amorphous nature and were readily soluble in a variety of organic solvents. Transparent, flexible, and tough films of these polymers could be cast from DMAc or NMP solutions. Their cast films had tensile strengths ranging from 64 to 116 MPa, elongations at break from 6 to 20%, and initial moduli from 2.18 to 3.90 GPa. The glass transition temperatures of these polymers were in the range of 247–324°C. Received: 13 April 1999/Revised version: 28 May 1999/Accepted: 26 June 1999     

Synthesis and characterization of 2,5-bis[4-(2-arylvinyl)phenyl]-1,3,4-oxadiazoles with two-photon fluorescence properties

Four novel 2,5-bis[4-(2-arylvinyl)phenyl]-1,3,4-oxadiazoles that exhibit strong two-photon absorption and enhanced two-photon excited fluorescence were designed and synthesized based on push-core-pull-core-push  molecules built from embedding electron-transporting 1,3,4-oxadiazole in aromatic conjugated system through Wittig-Horner reaction. Their chemical structures were determined to show trans-vinylene character according to infrared (IR) and ¹H nuclear magnetic resonance (NMR) spectra. A very effective energy transfer from the excited units to the ?-conjugated bridging unit can enhance the two-photon absorption and two-photon fluorescence.     

2，5-二（对烷氧基苯基）-1，3，4－噁二唑合成研究

1,3,4-噁二唑类很多领域都有广泛的应用。目前合成对称的2,5－二取代1,3,4－噁二唑的主要途径是在脱水剂存在的条件下,使酰氯和酰肼反应制备得对称的二酰胺脱水环合。以对羟基苯甲酸甲酯和对氰基苯酚为原料合成了2,5－二（对烷氧基苯基）．1,3,4－噁二唑类化合物,实验过程简单,条件温和,收率良好。实验中采用乙醇做溶剂,在滴加乙酰氯的情况下生成反应所需的氯化氢气体。这种方法避免了直接通入氯化氢带来的麻烦。产物的结构由^1HNMR和^13CNMR确定。     

Synthesis and Properties of Poly[p-(2,5-dihydroxy)-phenylenebenzobisoxazole] Fiber

The novel polymer poly[p-(2,5-dihydroxy)-phenylenebenzobisoxazole] (PBOH) fiber was synthesized in the presence of 2,5-dihydroxyterephthalicacid (DHTA) and 4,6-diamino-1,3-benzenediol in poly(phosphoric acid) (PPA) using typical polycondensation conditions. The crystalline solutions of liquid PBOH in PPA were spun into fibers using dry-jet wet spinning. Furthermore, the thermostability and mechanical properties of PBOH were compared with poly(p-phenylene-2,6-benzoxazole) (PBO) in order to investigate the relationship between the chain structure and properties. The results indicated that the thermal degradation temperature of PBOH was above 750K and the tensile strength of the PBOH fiber was 3.1GPa, which were much lower than those of PBO fiber. The compressive strength of PBOH fiber was 331 M Pa, which was slightly higher than that of PBO fiber. In addition, molecular simulation was employed to explain why the compressive strength of PBOH fiber did not increase significantly compared to PBO fiber.     

Synthesis and crystallinity of poly(butylene 2,5-furandicarboxylate)

Poly(butylene 2,5-furandicarboxylate) (PBF) was obtained by esterification of 2,5-furandicarboxylic acid (FDCA) and 1,4-butylene glycol (BG). By using ¹H NMR at 750 MHz to recognize the trace end groups at different polymerization stages, the study provides a clear picture that the polymerization proceeds cleanly to give the desirable linear structure. On the basis of the end group analysis, the degree of polymerization of PBF was determined to be as high as 125, which is in agreement with the molecular weight from the viscosity study. Solid state ¹³C NMR revealed that one of the furan carbons is sensitive to local morphology. DSC and X-ray diffraction further revealed that the polymer had high tendency to form crystalline materials (T_m = 130 °C & 169 °C; T_g = 32 °C). On the basis of DSC and NMR evidences, the two crystalline states are assumed to be β-phase (less stable) and α-phase (more stable), respectively, by analogy with the crystalline structure of PBT. High tendency of forming crystalline structure allows the continuous fibers to be drawn from the PBF's melt. The results thus raise the hope that the biomass-derived PBF could be a promising furan counterpart of the petroleum-based poly(butylene terephthalate) (PBT).     

Thermal decomposition behavior of poly[3,3-bis(ethoxymethyl) oxetane] and related polyethers

The thermal decomposition behavior of poly[3,3-bis(ethoxymethyl)oxetane] (polyBEMO) was examined and compared to the decomposition of poly(ethylene oxide) (PEO) and poly(tetramethylene oxide) (polyTHF). Differential scanning calorimetric (DSC) studies as a function of heating rates and at constant temperature as a function of time yielded activation energies of 45–50 kcal/mol, characteristic of polyether decomposition. First-order decomposition kinetics were found. The reaction is endothermic, with a heat of decomposition of 18.6 kcal/mol. Effusion mass spectroscopy on polyBEMO showed major peaks at 112, 140, 168, and 174 amu. A mechanism is proposed in which the thermal scission of the ether bonds in both the polymer chain and in the appendanges initiates the decomposition. The main decomposition reaction for polyBEMO can be written as where the appendages and main chain are cleaved in an unknown order.     

2，5-双[N-（乙酰乙酰）氨基]苯磺酸

介绍了2,5-二氨基苯磺酸的多种合成路线,并以2-氨基-5-硝基苯磺酸为原料经铁粉或Pd/C催化加氢还原制得2,5-二氨基苯磺酸,再经双乙烯酮乙酰乙酰化合成2,5-双[N-(乙酰乙酰)氨基]苯磺酸,总收率81%,产品纯度98%。     

Design and synthesis of 1,4-bis[4-(1,1-dicyanovinyl)styryl]-2,5-bis(alkoxy)benzenes as red organic electroluminescent PPV analogs

A series of 1,4-distyrylbenzene derivatives containing 1,1-dicyanovinyl moieties were designed as poly-p-phenylenevinylene analogs to obtain the red electroluminescence assisted by the computational results. Based on the subsequent synthesis and optical studies, the present work indicated that introduction of 1,1-dicyano group as electron receptor in PPV skeleton could shift the electroluminescence significantly to the red region. The present work has shown a successful strategy to tune the emission of PPV analogs based on the theoretical design and organic synthesis.     

Synthesis, characterization and optical properties of a regioregular and soluble poly[3-(10-hydroxydecyl)-2,5-thienylene]

The preparation of a regioregular trimethylsilanyloxydecyl 3-substituted polythiophene and its conversion to the corresponding hydroxydecyl polymer, which is soluble in common organic solvents, is described both in solution and in film. The chromic behaviour of the hydroxy functionalized polymer was investigated by UV-vis spectroscopy in different solvent/non-solvent mixtures and in the solid state by exposing the polymer adsorbed on hydroxylic matrices to methanol vapours.     

N,N’-二硝基-N,N’-二(3-([1,2,3]-三唑并[4,5-c]呋咱-4,5-内盐-5-基)呋咱-4-基)二氨基甲烷的合成与表征

以二氨基呋咱(DAF)为起始原料,经Caro's acid氧化、锌粉还原、环化、缩合和硝化五步反应得到N,N’-二硝基-N,N ’-二(3-([1,2,3]-三唑并[4,5-c]呋咱-4,5-内盐-5-基)呋咱-4-基)二氨基甲烷(MNOTO),总收率为32.7％(以DAF计).用元素分析、核磁共振、红外光谱等进行了结构表征.用浓硝酸和醋酐作为硝化体系硝化N,N’-二(3-([1,2,3]-三唑并[4,5-c]呋咱-4,5-内盐-5-基)呋咱-4-基)二氨基甲烷(MAOTO),考察了反应温度、反应时间以及浓硝酸与醋酐摩尔比对反应收率的影响,硝化体系中硝酸和醋酐的最佳摩尔比为1.5∶1,反应温度15～20℃,反应时间为5h.     

Synthesis and characterization of new soluble cardo poly(amide-imide)s derived from 2,2-bis[4-(4-trimellitimidophenoxy)phenyl]norbornane

A series of new soluble poly(amide-imide)s were prepared from the diimide-dicarboxylic acid, 2,2-bis[4-(4-trimellitimidophenoxy)phenyl]norbornane, and various diamines by the direct polycondensation in N-methyl-2-pyrrolidinone containing CaCl_2, using triphenyl phosphite and pyridine as condensing agents. All the polymers were obtained in quantitative yields with inherent viscosities of 1.01-1.42 dL g⁻¹. Gel permeation chromatography (GPC) of the polymers showed number-average and weight-average molecular weight up to 67,300 and 118,000, respectively. The poly(amide-imide)s were amorphous and were readily soluble in various solvents such as N-methyl-2-pyrrolidinone (NMP), N,N-dimethylacetamide (DMAc), N,N-dimethylformamide (DMF), dimethylsulfoxide (DMSO), pyridine, cyclohexanone and tetrahydrofuran. Tough and flexible films were obtained by casting their DMAc solution. The films had tensile strength of 89-110 MPa and a tensile modulus range of 1.8-2.2 GPa. The glass transition temperatures of the polymers were determined by DSC method and they were in the range of 265-295 °C. The polymers were fairly stable up to a temperature around or above 450 °C, and lose 10% weight in the range of 472-504 °C and 490-520 °C in nitrogen and air, respectively.     

5-硝基-2-磺酰基苯并呋喃的合成研究

以5-硝基水杨醛为起始原料,经Horner-Wittig反应、水解得到5-硝基-2-羟基肉桂酸。该中间体分别与不同电性基团取代的苯亚磺酸钠,在Cu(OAc)_2和Ag OAc双金属体系作用下,经串联式反应得到2个5-硝基-2-磺酰基苯并呋喃化合物。其结构经~1H NMR、~(13)C NMR确证。     

2,5-双(苯胺基)对苯二甲酸闭环反应合成喹吖啶酮

喹吖啶酮作为颜料、有机太阳能电池等材料的重要原料,其合成过程的闭环反应仍是目前研究的热点。本文以2,5-双(苯胺基)对苯二甲酸（DATA）为原料,在酸促进下进行闭环反应合成喹吖啶酮,通过正交实验考察了促进剂、投料比、加热温度和反应时间对产物收率的影响。实验结果表明,以十二烷基苯磺酸（DBSA）为促进剂,在投料比m(DATA)∶m(DBSA)=1∶4.3、反应温度130℃、反应时间7h的条件下,产物喹吖啶酮收率为92%。由极差R可知,影响喹吖啶酮产率的因素从主到次：酸的种类＞温度＞时间＞投料比。利用¹H NMR、FTIR和UV-vis,对产物和中间产物进行了结构表征;经SEM和TG-DSC热重分析表明产物的形貌规则,热稳定性良好;溶剂处理后,喹吖啶酮经过XRD检测分析为稳定的β-晶型。