Sulfur ylides 15. Intramolecular cyclization of new keto-stabilized sulfur bis-ylide

New sulfur bis-ylide was obtained from 3-amino-3-phenylpropionic acid and pyromellitic dianhydride. Its intramolecular cyclization proceeds regioselectively, leading to 3,4,11,12-tetrahydro-2H,6H-indolizino[2,1-f]pyrido[2,1-a]isoindole derivative in 66% yield. Phosphorus bis-ylide of similar structure gives a cyclization product in 10% yield. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2394–2396, December, 2007.     

Soluble poly(amide–imide)s prepared by one‐pot solution condensation

A new one‐pot procedure for imide–acid monomer synthesis and polymerization is reported for four new poly(amide–imide)s. Bisphenol A dianhydride (BPADA) was reacted with twice the molar amount of 3‐aminobenzoic acid (3ABA) or 3‐amino‐4‐methylbenzoic acid (3A4MBA) in 1‐methyl‐2‐pyrrolidinone (NMP) and toluene mixture, and the amic acid intermediates cyclized in solution to give two diimide‐containing dicarboxylic acid monomers. Without isolation, the diacid monomers were then polymerized with either 1,3‐diaminomesitylene (DAM) or 1,5‐diaminonaphthalene (1,5NAPda) using triphenyl phosphite‐activation to give a series of four soluble poly(amide–imide)s, PAI. Isolation and purification of the dicarboxylic acid monomers was not necessary for formation of high molecular weight polymers as indicated by intrinsic viscosities of 0.64–1.04 dL/g determined in N,N‐dimethylacetamide (DMAc). All of the PAI were soluble in polar aprotic solvents such as NMP, DMAc, and dimethyl sulfoxide (DMSO). Glass transition temperatures ranged from 243 to 279°C by DSC, and 5% weight loss temperatures were above 400°C in both air and nitrogen. Flexible films cast from DMAc were light yellow, transparent, and tough. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 1183–1188, 1999     

Synthesis and properties of poly(ether imide)s derived from 2,7-bis(3,4-dicarboxyphenoxy)naphthalene dianhydride and various aromatic diamines

A naphthalene unit-containing bis(ether anhydride), 2,7-bis(3,4-dicarboxyphenoxy)naphthalene dianhydride, was prepared in three steps starting from the nucleophilic nitrodisplacement reaction of 2,7-dihydroxynaphthalene and 4-nitrophthalonitrile in N,N-dimethylformamide (DMF) solution in the presence of potassium carbonate followed by alkaline hydrolysis of the intermediate bis(ether dinitrile) and subsequent dehydration of the resulting bis(ether diacid). High-molar-mass aromatic poly(ether imide)s were synthesized using a conventional two-stage polymerization process from the bis(ether anhydride) and ten aromatic diamines. The intermediate poly(ether amic acid)s had inherent viscosities of 0.95–2.67 dL/g. The films of poly(ether imide)s derived from two rigid diamines, that is, p-phenylenediamine and benzidine, crystallized and embrittled during the thermal imidization process. The other poly(ether imide)s belonged to amorphous materials and could be fabricated into transparent, flexible, and tough films. These poly(ether imide) films had yield strengths of 91–115 MPa, tensile strengths of 89–136 MPa, elongation to break of 11–45%, and initial moduli of 1.7–2.2 GPa. The T_gs of poly(ether imide)s were recorded in the range of 222–256°C depending on the nature of the diamine moiety. All polymers were thermally stable up to 500°C, with 10% weight loss being recorded above 540°C in air and nitrogen atmospheres. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 2281–2287, 1997     

The Crystal Structure of Biphenyltetracarboxylic Dianhydride Isomers

１　ＩＮＴＲＯＤＵＣＴＩＯＮＡｒｏｍａｔｉｃｐｏｌｙｉｍｉｄｅｓａｒｅａｃｌａｓｓｏｆｐｏｌｙｍｅｒｓｋｎｏｗｎｆｏｒｔｈｅｉｒｈｉｇｈｔｅｍｐｅｒａｔｕｒｅｓｔａｂｉｌｉｔｙ,ｅｘｃｅｌｌｅｎｔｅｌｅｃｔｒｉｃａｌａｎｄｍｅｃｈａｎｉｃａｌｐｒｏｐｅｒｔｉｅｓ．Ｔｈｅｓｅｐｒｏｐｅｒｔｉｅｓｍａｋｅｔｈｅｍｈｉｇｈｌｙｄｅｓｉｒａｂｌｅｆｏｒｈｉｇｈｐｅｒｆｏｒｍａｎｃｅａｐｐｌｉｃａｔｉｏｎｓ〔１〕．Ｈｏｗｅｖｅｒ,ｔｒａｄｉｔｉｏｎａｌｐｏｌｙｉｍｉｄｅｓｓｕｃｈａｓＵＰＩＬＥＸＲａｎｄ…     

Small Figure-Eight Luminophores: Double-Twisted Tethered Cyclic Binaphthyls Boost Circularly Polarized Luminescence

Double-twisted cyclic binaphthyls, in which two naphthalenes are tethered by -O(CH₂)_nO- linkage (n=1–3), have been synthesized. X-ray analyses and DFT calculations revealed a tightly constrained stereogenic figure-eight geometry. Tethering of two naphthalenes by short linkage forces a small dihedral angle, and the cyclic binaphthyls with short tether (n=1, 2) exhibit remarkable boosting of the g_lum value (1.0–1.6×10⁻²) in circularly polarized luminescence (CPL) and unusual g_lum/g_abs ratios (0.93–1.3). These experimental high |g_lum| values are in accord with the results of excited state TD-DFT calculations, which show transannular interactions and that consequent extensive delocalization occurs throughout the figure-eight π-core. As a result, the present figure-eight luminophore promote the elongation of the magnetic transition dipole moment that results in significant increases in g_lum values.     

红色荧光联苯四甲酸碱式稀土配合物的合成及发光性能

以3,3',4,4'-联苯四甲酸二酐(BPDA)为配体原料合成了两种碱式铕和铽配合物,通过元素分析、红外光谱和热重分析等测试技术表征了配合物的结构组成,用紫外光谱和荧光光谱研究了配合物的发光性能。结果表明:两种配合物的组成分别为Tb₅L₃(OH)₃·8H₂O和Eu₅L₃(OH)₃·10H₂O(L=BPDA),稀土铕(Ⅲ)和铽(Ⅲ)与羧酸根的配位方式主要以桥式配位为主,兼有少量螯合配位。这些配合物的热稳定性能良好。铽配合物和铕配合物均呈现红色荧光,铽配合物归属于⁵D₄→⁷F₃跃迁(613 nm)的荧光寿命为491.11 μs,归属于⁵D₄→⁷F₅ 跃迁(544 nm) 的荧光寿命为27.9 μs;铕配合物归属于⁵D₀→⁷F₂ 跃迁 (613 nm) 的荧光寿命为329.5 μs,荧光量子产率为13.05%。     

Novel ortho‐linked fluorinated poly(ether‐imide)s based on 2,2′‐substituted 1,1′‐binaphthyl units

In this research, a new fluorinated diamine based on 2,2′‐substituted 1,1′‐binaphthyl units, 2,2′‐bis(2‐amino‐4‐trifluoromethylphenoxy)‐1,1′‐binaphthyl (AFPBN) was synthesized and then used to prepare the corresponding ortho‐linked poly(ether‐imide)s via chemical polyimidization with several aromatic carboxylic dianhydrides. The resulting poly(ether‐imide)s were fully characterized by FT‐IR, NMR, viscosity measurements, gel‐permeation chromatography, UV–vis, X‐ray diffraction, organo‐solubility, thermogravimetric analysis (TGA), and differential scanning calorimetry. Probing optical behavior of the colorless films prepared from these poly(ether‐imide)s demonstrated that they possess a high degree of optical transparency, and UV–visible absorption cut‐off wavelength values were found to be in the range of 404–471 nm. The resulting polymers exhibited excellent organo‐solubility in polar solvents such as dimethylformamide, dimethyl sulfoxide, pyridine, and even tetrahydrofuran. To investigate the heat stability of the samples, their thermograms obtained from TGA were plotted, and for example, it is found that the 10% weight loss temperature of representative polymer AFPBN/3,3′,4,4′‐benzophenonetetracarboxylic dianhydride occurred at 532°C in nitrogen. These poly(ether‐imide)s had glass‐transition temperatures (T_g's) up to 280°C. Two previously prepared analogues of AFPBN, i.e. nonfluorinated diamine DAM1 and para‐linked fluorinated diamine DAM2 used to prepare the corresponding poly(ether‐imide)s, were also considered to compare the results obtained. Copyright © 2012 John Wiley & Sons, Ltd.     

Crosslinking of Polydimethyl Siloxane Copolymers with Aromatic Dianhydrides: The Study of Thermal and Flame Retardant Properties †

Aromatic dianhydrides have been identified as potential candidates for crosslinking with biocatalytically synthesized siloxane copolymers containing a functional amino group on the isophthalate moieties. We present the synthesis, characterization, thermal and flame retardant properties of this novel class of crosslinked organo-siloxane copolymers. We also discuss the effect of the concentration of one of the crosslinkers, 1,2,4,5-benzenetetracarboxylic dianhydride (DAH), on thermal decomposition and flame retardant properties using thermogravimetric analysis (TGA) and pyrolysis combustion flow calorimetry (PCFC) studies. The char yields were improved in all the polymers crosslinked with the various aromatic dianhydrides. The heat release capacity of a polymer crosslinked with 20% DAH, compared to the pure polymer, was tremendously reduced from 190 J/gK to 100 J/gK. The decomposition kinetics from TGA showed that the crosslinked polymer is thermally more stable than the non-crosslinked polymer.