Copolymerization of benzoquinone with norbornene

For the first time, the conjugated dicarbonyl compound benzoquinone has been copolymerized with the strained cyclo-olefin norbornene using catalytic amounts of the Friedel-Crafts metathesis catalytic system WOCl₄+AlCl₃. All analyses reveal that the products consist of conjugated blocks originating from benzoquinone connected with spacers originating from norbornene. The products are soluble in benzene, toluene, chlorobenzene, etc. but possess properties of the conjugated polymers. They have been synthesized via a very simple one-pot procedure.     

Third-order nonlinear optical studies of newly synthesized polyoxadiazoles containing 3,4-dialkoxythiophenes

The third-order nonlinear optical properties of newly synthesized soluble polyoxadiazoles containing 3,4-dialkoxythiophenes were investigated by using Z-scan and degenerate four-wave mixing (DFWM) techniques. The measurements were performed at 532 nm with 7 ns pulses from a Nd:YAG laser. We found a good agreement between the values of χ⁽³⁾ determined from both the experiments. Z-scan results indicate a negative nonlinear refractive index, n₂, whose magnitude is of the order of 10⁻¹⁰ esu for all the copolymers. The variation of nonlinear response among the copolymers clearly indicates the dependence of χ⁽³⁾ on donor and acceptor type of units present in these copolymers. The copolymers exhibit strong reverse saturable absorption and good optical limiting properties at 532 nm.     

Correlation between spectroscopic and morphological properties of composite P3HT/PCBM nanoparticles studied by single particle spectroscopy

We report the fabrication and characterization of composite nanoparticles consisting of a conducting polymer, poly-3-hexylthiophene (P3HT), doped with varying amounts of [6,6]-phenyl C61-butyric acid methyl ester (PCBM), a material blend that is commonly applied in bulk heterojunction organic photovoltaic devices (OPVs). Single particle spectroscopy (SPS) studies, where nanoparticles are studied one particle at a time, reveal that these nanoparticles have spectroscopic characteristics consistent with the existence of two types of crystalline nanodomains, one with a higher energy emission at 660 nm and one with a lower energy emission at 720 nm. In addition, the occurrence of emission at lower peak energy increases with increasing PCBM doping levels, and the intensity of the lower energy peak emission increases with respect to the higher energy peak emission as well. These data reveal a PCBM concentration dependent formation of two types of P3HT crystalline nanodomains in P3HT/PCBM composite nanoparticles, where the lower energy crystal structure becomes more favored with higher PCBM concentration. This work provides a molecular scale insight in the correlation between changes in morphology of conjugated polymer materials with different weight percentages of fullerene dopants.     

Fisher-like atomic divergences: Mathematical grounds and physical applications

Two different local divergence measures, the Fisher (FD) and the Jensen–Fisher (JFD) ones, are compared in this work by applying them to atomic one-particle densities in position and momentum spaces. They are defined in terms of the absolute and the relative Fisher information functionals. The analysis here afforded includes not only neutral atoms, but also singly-charged cations. The results are interpreted and justified according to (i) shell-filling patterns, (ii) short- and long-range behaviors of the atomic densities, and (iii) the value of the atomic ionization potential. The strengths of the FD measure, as compared to the JFD one, are emphasized.     

Palladium catalyzed cross-dimerization of terminal acetylenes and acrylates

A palladium catalyzed oxidative cross-coupling reaction between terminal alkynes and acrylates was developed. In the presence of palladium catalyst and copper(II) acetate as oxidant, the cross dimerization products with were formed. This protocol provides a novel method to construct the tetrasubstituted functionalized alkenes.     

通过调节共轭聚合物侧链实现可绿色溶剂加工的非富勒烯太阳能电池

有机太阳能电池(OSC)经过长期的发展,其能量转换效率(PCE)已快速推进至14%–16%,基本接近可商业化应用的范围,但在目前所见报道的高效率OSC器件的制备过程中,活性层薄膜的加工大多采用氯苯、二氯苯、氯仿等毒性较高的含卤/芳香性试剂,此类试剂对环境及人类健康的危害非常高。在本工作中,我们基于已报道的高效率给体共轭聚合物PBDB-T,通过扩大共轭侧链结构与增长柔性烷基侧链的方式,合成了新型给体聚合物PBDB-DT。PBDB-DT中较长的柔性烷基侧链保证了其在低毒性溶剂四氢呋喃(THF)溶液中良好的溶解度,同时,扩大的共轭侧链也有效增强了其在THF中的溶液聚集作用,这一特性对于在非富勒烯型OSC器件中获得较好的光伏性能尤其重要。当采用非富勒烯小分子IT-M作为电子受体材料时,以THF为主溶剂加工的基于PBDB-DT:IT-M的OSC器件可以获得10.2%的能量转换效率。     

Synthesis of Conjugated Polymers via Transition Metal Catalysed C−H Bond Activation

Transition metal catalysed C−H bond activation chemistry has emerged as an exciting and promising approach in organic synthesis. This allows us to synthesize a wider range of functional molecules and conjugated polymers in a more convenient and more atom economical way. The formation of C−C bonds in the construction of pi-conjugated systems, particularly for conjugated polymers, has benefited much from the advances in C−H bond activation chemistry. Compared to conventional transition-metal catalysed cross-coupling polymerization such as Suzuki and Stille cross-coupling, pre-functionalization of aromatic monomers, such as halogenation, borylation and stannylation, is no longer required for direct arylation polymerization (DArP), which involve C−H/C−X cross-coupling, and oxidative direct arylation polymerization (Ox-DArP), which involves C−H/C−H cross-coupling protocols driven by the activation of monomers’ C(sp²)−H bonds. Furthermore, poly(annulation) via C−H bond activation chemistry leads to the formation of unique pi-conjugated moieties as part of the polymeric backbone. This review thus summarises advances to date in the synthesis of conjugated polymers utilizing transition metal catalysed C−H bond activation chemistry. A variety of conjugated polymers via DArP including poly(thiophene), thieno[3,4-c]pyrrole-4,6-dione)-containing, fluorenyl-containing, benzothiadiazole-containing and diketopyrrolopyrrole-containing copolymers, were summarized. Conjugated polymers obtained through Ox-DArP were outlined and compared. Furthermore, poly(annulation) using transition metal catalysed C−H bond activation chemistry was also reviewed. In the last part of this review, difficulties and perspective to make use of transition metal catalysed C−H activation polymerization to prepare conjugated polymers were discussed and commented.     

含芴共轭高分子的合成、表征及性能研究——推荐一个高分子化学综合实验

推荐了一个高分子化学综合实验——含芴共轭高分子的合成、表征及性能研究。实验内容包括利用Sonogashira偶联反应合成共轭高分子,采用核磁共振和红外光谱等检测手段对其结构进行表征,并利用紫外-可见光谱、荧光和热重分析对其性能进行研究。本实验结合了高分子化学和聚合物仪器分析与表征的知识点,建议纳入高分子专业高年级综合实验课程。     

Pd-catalyzed oxidative homo-coupling of acrylates and aromatic alkenes for the conjugated diene synthesis

We developed a bidentate monoanionic nitrogen ligand that was effective in the Pd-catalyzed oxidative homo-coupling reaction of acrylates and aromatic alkenes. In the presence of Pd(OAc)₂/ligand several conjugated dienes were obtained in good yields with high stereoselectivities.