The synthesis of a precursor of polybenzimidazole (PBI) and blends with polyamic acid (PAA)

The precursor of polybenzimidazole (PBI), poly(3,3′-diamino-4,4′-benzidine isophthalamide) (PDABI), was synthesized from poly(3,3′-dinitro-4,4′-benzidine isophthalamide) (PDNBI) by reduction. With increasing temperature, the NH₂ moiety which was protected by SnCl₅^?1 could cyclize and form PBI. Blends with polyamic acid (LaRC-TPI) were prepared. Clear blend films were prepared at up to 400°C. The IR spectra displayed shifts in the NH stretching band, thereby providing evidence for specific interactions related to the miscibility of their cured blends. © 1993 John Wiley & Sons, Inc.     

咪喹莫特的波谱学数据与结构表征

对咪喹莫特的红外(IR)、紫外(UV)、质谱(MS)、氢-氢相关谱(^1H--^1H COSY)、碳氢相关谱(HMQC)、碳氢远程相关谱(HMBC)予以解析并进行了报道。对所有的^1H NMR、^13C NMR谱的信号进行了归属；讨论了质谱的主要碎片离子的可能的裂解方式和红外特征吸收峰所对应的官能团的振动形式。     

Vibronic intensities in centrosymmetric lanthanide complex ions. I

Summary A theoretical model to calculate the vibronic intensities induced by the odd vibrational modes in centrosymmetric lanthanide complexes is developed and applied to octahedral complex ions, LnX ₆ ^3– , such as occur in the hexachloroelpasolites Cs₂NaLnCl₆. Both the crystal field and the ligand polarisation contributions are evaluated using a standard set of symmetry coordinates. For the crystal field term a truncated expansion of the intermediates states is employed rather than the more conventional closure approximation. Special care is necessary to ensure that the phases of the contributions are correctly determined since the cross-term between the ligand polarisation and crystal field contributions is signed. General equations applicable to anyf ⁿ complex ion are derived and an example of their application to the PrCl ₆ ^3– ion is given The agreement with experiment is satisfactory.     

Progress on phthalocyanine-conjugated Ag and Au nanoparticles: Synthesis,characterization, and photo-physicochemical properties

Phthalocyanine (Pc) complexes are an important class of dyes with numerous (e.g., biological, photophysical, and analytical) applications. Among the methods used to improve the properties of these complexes, one should mention the introduction of different substituents, variation of the central metal ion, ligand exchange, and conjugation to nanomaterials (e.g., carbon-based nanomaterials and metal nanoparticles (NPs)). This work briefly reviews Pc complex conjugation to Ag and Au NPs, highlights the different NP shapes, and discusses the diversity of conjugation approaches. Moreover, the use of UV–Vis spectroscopy, powder X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, atomic force microscopy, dynamic light scattering and Fourier transform infrared spectroscopy to characterize Pc-NP hybrids is summarized. The effect of conjugation on Pc photo-physicochemical properties (fluorescence, singlet oxygen generation, triplet state formation, and optical limiting behavior) is discussed, and future perspectives for the synthesis and applications of new hybrids are provided.     

Heat-resistant polymers from melt-processable bisimido-bisphthalonitriles

Heat-resistant polymers which are processable into void-free components and suitable for composite applications have been synthesized by thermal/chemical polymerization of four newly developed bisimido-bisphthalonitriles containing silicon, ether, carbonyl, and hexafluoroisopropylidene groups. Thermal polymerization involving addition reactions was performed at 200–275°C for 2–10 h and then post-curing at 310°C for 10 h. Polymers VI, VII, VIII , and IX were obtained. The thermal polymerization was monitored using infrared spectroscopy. Thermal polymerization was also carried out in the presence of an aromatic diamine. A polyhexasocyclane ( V ) was synthesized by condensation polymerization of ether containing bisimido-bisphthalonitrile with 4,4′-diaminodiphenyl ether in solvent phenol. The synthesized polymers were evaluated for thermal stability using dynamic thermogravimetric analysis (TGA). Polymers VII, VIII, IX , and X showed thermal decomposition temperature in the range of 475–500°C in nitrogen and air atmosphere. The char yield of the polymers was in the range of 60–69% in nitrogen at 800°C. This study indicated that synthesized thermosetting polymers from ether and keto containing bisimido-bisphthalo-nitrile are potential candidates for development of graphite composites. © 1993 John Wiley & Sons, Inc.     

Simultaneous measurement of glucose and glutamine in aqueous solutions by near infrared spectroscopy

A method is described for measuring the concentrations of both glucose and glutamine in binary mixtures from near infrared (NIR) absorption spectra. Spectra are collected over the range from 5000–4000/cm (2.0–2.5μm) with a 1-mm optical path length. Glucose absorbance features at 4710, 4400, and 4300/cm and glutamine features at 4700, 4580, and 4390/cm provide the analytical information required for the measurement. Multivariate calibration models are generated by using partial least squares (PLS) regression alone and PLS regression combined with a preprocessing digital Fourier filtering step. The ideal number of PLS factors and spectral range are identified separately for each analyte. In addition, the optimum Fourier filter parameters are established for both compounds. The best overall analytical performance is obtained by combining Fourier filtering and PLS regression. Glucose measurements are established over the concentration range from 1.66–59.91 mM, with a standard error of prediction (SEP) of 0.32 mM and a mean percent error of 1.84%. Glutamine can be measured over the concentration range from 1.10–30.65 mM with a SEP of 0.75 mM and a mean percent error of 6.67%. These results demonstrate the analytical utility of NIR spectroscopy for monitoring glucose and glutamine levels in mammalian and insect cell cultures.     

Far infrared spectra of solid molecular nitrogen

This paper reports the observation of the far infrared absorption spectrum of a single crystal of N₂, measured over absorption paths of 4 cm (lengthwise) and 2 cm (across the crystal). The crystal chamber, with quartz windows, was immersed in a flow of cold helium gas. The spectrum from 20 to 120 cm^–1 was recorded in the liquid phase, the-phase, and over the full temperature range of the-phase (35.6–2.0 K) with a Fourier transform spectrometer. The spectral resolution, which was not instrument-limited, and the large path allowed the observation of more detailed multiphonon-transition structure in the spectrum of the-phase than has previously been observed.     

Application of online near infrared spectroscopy to study the kinetics of anionic polymerization of butadiene

Online Fourier-transform near infrared (FT-NIR) spectroscopy in combination with a fiber optic probe was utilized to study the kinetics of the anionic polymerization of butadiene. The conversion of the butadiene to methylene protons in the polymer was monitored in solution polymerization conditions by monitoring the absorbance at 1632 nm. The off-line gel permeation chromatography, GPC, technique was used to validate the online FT-NIR spectroscopy method. Butadiene polymerization kinetics in cyclohexane initiated with n-butyllithium at different initiator concentrations and temperatures was studied. A phenomenological kinetic expression for the anionic polymerization of butadiene in cyclohexane initiated with n-butyllithium was determined. The predictions of the kinetic expression were in agreement with kinetic data reported in the literature.     

Concentrated electrolyte solutions at high temperatures and pressures

A survey is given of recent experimental results obtained from high-temperature, high-pressure investigations with water, aqueous solutions, and ionic fluids. Data on the static dielectric constant of water to 550°C and 5 kbar are given and discussed with respect to their relation to water structure. Infrared and Raman spectra of HDO in pure water have been obtained to 400°C and 4 kbar, which give information on hydrogen bonding. Xe–H₂O and CO₂–H₂O mixtures were investigated in the infrared. Ni(II) and Cu(II) complexes were investigated by absorption spectroscopy in aqueous solutions of high chloride content to 350°C and 2–6 kbar. The gas-liquid critical point of ammonium chloride was found at 880°C and 1635 bars. This fluid appears to be predominantly ionic even in the critical region. The possibility of converting pure polar fluids such as ammonia and water into concentrated ionic solutions by self-ionization at very high pressures is mentioned.This paper was presented at the symposium, The Physical Chemistry of Aqueous Systems, held at the University of Pittsburgh, Pittsburgh, Pennsylvania, June 12–14, 1972, in honor of the 70th birthday of Professor H. S. Frank.     

膦、胂叶立德的化学与应用——Ⅰ.用红外光谱对膦、胂叶立德结构的研究

以78个带吸电子取代基的膦、胂叶立德的红外光谱的解析为根据,讨论了它们的结构及其与光谱的关系。