Structural verification of a tetrahydrotetrazole compound

Tetrahydrotetrazoles are five‐membered‐ring heterocycles containing four contiguous saturated nitrogen atoms. Very few examples of such compounds have been reported in the literature. Our previous attempt at the synthesis of a member of this class of compound suggested that the N—N bonds may be more labile than expected. This finding raised the question as to whether the structures of any of the previously reported tetrahydrotetrazoles had been properly assigned. We have reproduced the synthesis of a reported tetrahydrotetrazole, namely 1,2‐di‐tert‐butyl 3‐phenyl‐1H,2H,3H,10bH‐[1,2,3,4]tetrazolo[5,1‐a]isoquinoline‐1,2‐dicarboxylate, C₂₅H₃₀N₄O₄, and have now confidently confirmed its structure via X‐ray crystallography. However, while sufficiently stable in the crystal phase, we discovered that it remains very labile in solution (having a half‐life of only 15 min at 20 °C in CDCl₃). A tentative reaction pathway for its dissociation based on ¹H NMR spectral evidence is provided.     

Photoisomerisation in Aminoazobenzene‐Substituted Ruthenium(II) Tris(bipyridine) Complexes: Influence of the Conjugation Pathway

Transition‐metal complexes containing stimuli‐responsive systems are attractive for applications in optical devices, photonic memory, photosensing, as well as luminescence imaging. Amongst them, photochromic metal complexes offer the possibility of combining the specific properties of the metal centre and the optical response of the photochromic group. The synthesis, the electrochemical properties and the photophysical characterisation of a series of donor–acceptor azobenzene derivatives that possess bipyridine groups connected to a 4‐dialkylaminoazobenzene moiety through various linkers are presented. DFT and TD‐DFT calculations were performed to complement the experimental findings and contribute to their interpretation. The position and nature of the linker (ethynyl, triazolyl, none) were engineered and shown to induce different electronic coupling between donor and acceptor in ligands and complexes. This in turn led to strong modulations in terms of photoisomerisation of the ligands and complexes.     

The synthesis of azo compounds from nitro compounds using lead and triethylammonium formate

Aromatic nitro compounds were reduced to the corresponding symmetrically substituted azo compounds using lead as catalyst and triethylammonium formate as hydrogen donor. Various azo compounds containing additional reducible substituents including halogens, nitrile, acid, phenol, ester, methoxy functions, etc, have been synthesized in a single step by the use of this reagent. The conversion is reasonably fast, clean, high yielding and occurs at room temperature in methanol.     

Stimuli‐responsive polymers. VIII. Polyesters and poly(ester amides) containing azobenzene and chiral binaphthylene segments: Highly adaptive materials endowed with light‐, heat‐, and solvent‐regulated optical rotatory power

Azobenzene‐modified polyesters and poly(ester amide)s fitted with chiral, atropisomeric binaphthylene segments were prepared by a series of low‐temperature polycondensation reactions carried out in polar solvent media. When compared with their polyaramide counterparts studied earlier, these materials had significantly improved solubility behaviors and were readily dissolved by a wide range of organic solvents. In solution, each of these constructs underwent photoinduced oscillations in optical rotatory power when subjected to multiple UV‐light/visible‐light illumination cycles that drove trans?cis isomerization reactions along their polymer chains. Light‐regulated chiroptical perturbations were dependent on polymer backbone structures and were further modulated by well‐coordinated temperature fluctuations and by the nature of the solvent medium employed. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 207–218, 2006     

Polymer electrolyte membranes for the direct methanol fuel cell: A review

The direct methanol fuel cell (DMFC) has the potential to replace lithium‐ion rechargeable batteries in portable electronic devices, but currently experiences significant power density and efficiency losses due to high methanol crossover through polymer electrolyte membranes (PEMs). Numerous publications document the synthesis and characterization of new PEMs for the DMFC. This article reviews this research, transport phenomena in PEMs, and experimental techniques used to evaluate new PEMs for the DMFC. Although many PEMs do not show significant improvements over Nafion®, the benchmark PEM in DMFCs, experimental results show that several new PEMs exhibit lower methanol crossover at similar proton conductivities and/or higher DMFC power densities. These results and recommendations for future research are discussed. © 2006 Wiley Periodicals, Inc. J Polym Sci Parts B: Polym Phys 44: 2201–2225, 2006     

水溶性聚酯的结构和性能

由对苯二甲酸二甲酯、间苯二甲酸、间苯二甲酸二甲酯５－磺酸钠与乙二醇等共缩聚合成的ＰＥＴ型水溶性聚酯（ＷＳＰ）是一种新型的水溶性聚合物，在化纤、纺织、涂料、粘合剂、电子、油墨等领域有着广泛的应用前景．化纤领域超细纤维新材料的研究、开发和生产，迫切需要一...     

Photografting of vinyl polymers onto ultrafine inorganic particles: Photopolymerization of vinyl monomers initiated by AZO groups introduced onto these surfaces

The photografting of polymers onto ultrafine inorganic particles, such as silica and titanium oxide, initiated by azo groups introduced onto these surfaces was investigated. The introduction of azo groups onto the particles was achieved by the reaction of 4,4′-azobis(4-cyanopentanoic acid) with surface isocyanate groups, which were introduced by the treatment with tolylene 2,4-diisocyanate. It was found that the photopolymerization of vinyl monomers, such as methyl methacrylate (MMA), styrene, and N-vinylcarbazole, is initiated by ultrafine particles having azo groups. The corresponding polymers were effectively grafted onto these surfaces through the propagation of the polymer from the surface radicals formed by the photodecomposition of the azo groups: e.g., the percentage of grafting of PMMA and polystyrene onto silica was reached to 112 and 176%, respectively. The percentage of grafting onto silica in the graft polymerization initiated by photodecomposition of surface azo groups was much larger than that initiated by thermal decomposition. Polymer-grafted ultrafine particles thus obtained gave a stable colloidal dispersion in good solvents for the grafted chain. © 1994 John Wiley & Sons, Inc.     

新试剂3,5—二溴—4—偶氮8—羟基喹啉苯基荧光酮光度法测定微量铝

在溴化十六烷基三甲胺（ＣＴＭＡＢ）存在下，ＰＨ６，０的ＨＡｃ－ＮａＡｃ缓冲介质中，铝与新试剂３，５－二溴－４－偶氮８－羟基喹啉苯基荧光酮形成红色三元胶束配合物，最大吸收波长位于５６４ｎｍ，表观摩尔吸光系数ε为１．３５×１０＾５．ｍｏｌ＾－１．ｃｍ＾－１，铝浓度在０～５μｇ／２５ｍＬ范围内符合比耳定律，拟定的方法用于铝铁黄铜中微量铝的测定，结果满意。     

壳聚糖固体聚合物电池用膜

壳聚糖是甲壳素脱乙酰基的产物，具有良好的成膜性、生物相容性、环保以及价格低廉等特点。作为一种碱性高分子膜材料，近年来已成为聚电解质研究领域中的研究热点。本文综述了壳聚糖固体聚合物电池用膜的研究现状，其改性工艺主要包括共混、化学改性、质子酸掺杂、无机盐掺杂等方法，比较了各种工艺处理后壳聚糖固体聚合物电解质膜的性能差异，并就壳聚糖固体聚合物电解质膜中离子传导机理中有待解决的问题进行探讨，并提出了进一步改进壳聚糖固体聚合物电解质膜性能的研究思路。     

聚电解质溶液中2.6-ANS探针的荧光谱研究

本文合成了2.6—ANS荧光探针分子,并在含有不同外加盐的NaPSS溶液中测定了探针的荧光发射光谱。结果表明:探针的荧光强度随Cs增大而增大,而探针光谱的最大发射波长和半波宽度随Cs增大而减小。当Cs达到一定值时,荧光谱参数与Cs关系曲线出现转折点,此时聚离了链以“类胶束”状态存在。