【作者】 冀海英；

【导师】 高国华；

【作者基本信息】 华东师范大学 ， 物理化学， 2010， 博士

【摘要】 联芳类化合物因其具有特殊的光学和电化学性能,应用非常广泛,如可用于液晶材料、有机功能材料、医药、农药和有机合成中间体等领域。一些含有特殊官能团（如巯基、硝基等）的联芳类化合物因为具有特殊的光电性能,受到了广大科学家的广泛关注。比如含硝基的化合物经过进一步反应可生成具有良好光电性能的咔唑或多聚咔唑;含巯基的化合物可在金、银等金属表面形成自组装单分子膜,而以共轭有机薄膜为基础的电子器件可应用于有机电致发光器件、有机负电阻器件、分子电路器件及超微型芯片、超高密度信息纪录技术等方面。目前,合成联芳类化合物的主要方法就是偶联反应。结合该领域的研究现状,本论文主要研究了以下内容:采用钯催化的Suzuki偶联反应和Sonagashira偶联反应,共合成了3个系列39个未见文献报道的结构新颖的联芳类化合物,通过核磁、红外、元素分析和高分辨质谱等测试手段对所合成的新化合物进行了结构表征,测试了所合成化合物的紫外光谱、荧光光谱,讨论了结构与性能间的关系。用热重分析测试了热稳定性,循环伏安法测试了部分化合物的电化学行为,高斯软件计算了化合物的最优分子构型、最高占有轨道（HOMO）以及最低空轨道（LUMO）的能级。在Pd（PPh₃）₄催化剂存在下,4-溴-1-碘-2-硝基苯与对硫甲基苯硼酸反应,区域选择性地合成了4′-溴-2′-硝基-4-硫甲基联苯（3）,收率高达87%。化合物3进一步与不同芳基硼酸进行Suzuki偶联反应合成了17个含硝基和硫甲基的不对称联芳类化合物（4a-q）。紫外光谱结果表明,化合物4a-q的最大紫外吸收波长范围是241～318 nm。化合物4″-甲酰基-4-硫甲基-2′-硝基-1,1′,4′,1″-三联苯（4j）较其它不对称的三联苯化合物具有较大的紫外吸收波长299 nm。含杂环的化合物2-（4′-硫甲基）-2-硝基联苯-4-)苯并噻吩（4p）具有最大的紫外的吸收波长（318 nm）。热重分析结果表明,这一系列化合物具有较好的热稳定性,失重5%时的温度都在200℃以上。循环伏安测试结果表明,该系列化合物的氧化部分均不可逆,还原部分出现两个明显的还原峰,-1.22 V处的还原峰是可逆的。以Pd（PPh₃）₄为催化剂,碳酸钾为缚酸剂的条件下,1,4-对苯二硼酸频哪醇酯与取代的4-溴-2-硝基联苯（6a-d）进行双Suzuki偶联反应,一步合成了对称的含硝基五联苯类化合物（7a-d）,收率为44～75%。类似地,2,5-二硼酸频哪醇酯噻吩与取代的4-溴-2-硝基联苯（6a-d）也可以进行双Suzuki偶联反应,反应在Pd（PPh₃）₄为催化剂,氟化铯为缚酸剂,1,4-二氧六环为溶剂的条件下,生成的对称含硝基的噻吩/苯共聚物（9a-d）的收率为30～80%。紫外光谱结果表明,取代的五联苯类化合物（7a-d）的最大紫外吸收波长范围是295～307 nm,其最大吸收波长与苯环上的取代基性质有关,供电子基团使其最大紫外吸收波长红移,其最大紫外吸收波长的顺序为H（7a）＜Et（7b）＜OMe（7c）＜SMe（7d）;含硝基的噻吩/苯共聚物（9a-d）的最大紫外吸收波长范围是343～348 nm,同样,供电子基团使其最大紫外吸收波长红移,其最大紫外吸收波长的顺序为H（9a）＜Et（9b）＜OMe（9c）≈SMe（9d）。化合物7a-d同9a-d的最大紫外吸收波长相比发现:化合物9a-d的最大紫外吸收波长发生较大红移。热重分析结果表明,取代的五联苯类化合物（7a-d）和噻吩/苯共聚物（9a-d）都具有良好的热稳定性,失重5%时的温度都大于200℃。循环伏安测试结果可知,化合物7a-d和化合物9a-d的氧化部分不可逆,还原部分在-1.22 V处的还原峰是可逆的。采用汇聚式的合成方法即Suzuki偶联反应结合Sonogashira偶联反应合成了14个新型的寡聚苯乙炔撑（oligo（phenylene-ethynylene）s,OPEs）衍生物。首先,Pd（PPh₃）₄作催化剂,K₂CO₃作碱,DME作溶剂的条件下,4-溴-2-硝基苯乙炔基三甲基硅烷（10）与不同取代苯硼酸进行Suzuki偶联反应生成化合物11a-m,然后脱保护生成相应的含硝基联苯乙炔化合物（12a-m）。其次,以Pd₂（dba）₃作催化剂,CuI作共催化剂,PPh₃作配体,（i-Pr）₂NEt作碱的条件下,对硫乙酰基碘苯（13）与不同取代的化合物（12a-m）反应生成OPEs衍生物14a～m。化合物17的合成与此相似。紫外光谱结果表明,化合物14a～m和17的最大紫外吸收波长范围是304～321 nm。一般来说,引入的取代基团无论是吸电子基团还是供电子基团,最大紫外吸收波长发生明显红移现象（只有一个例外,14a蓝移）。化合物S-4-（4′-硫甲基-3-硝基联苯-4-乙炔基）苯硫乙酰酯（14m）具有最大的紫外吸收波长321nm。热重分析结果表明,OPEs衍生物都具有非常好的热稳定性,失重5%时的温度都在200℃以上。循环伏安测试结果表明,OPEs衍生物的氧化部分不可逆,还原部分在-1.1 V左右的峰是可逆的。更多还原

【Abstract】 Currently,polyaryls are materials of considerable interest for chemists,physicists, and material scientists,which are found at the core of a wide variety of interesting organic molecules,ranging from pharmaceutical agents,liquid-crystalline molecules, pesticides,dyes,nano-matefials to OLED materials.Polyaryls,which contained functional groups such as nitro group and thiol group,have been the focus of intense research because of their interesting optical and electrical properties.For instance, polyaryls containing nitro group could be transformed to polyindolocarbazole and polydiindolocarbazole,which showed good optical and electrochemical properties. Polyaryls containing thiol group can form self-assembled monolayers（SAMs） on the surface of Au,Ag or other metals.SAMs plays an important role in the construct ordered nanostructure in molecular electronics.Substituting conjugated organic thin-film-based electronic devices can be used in light-emitting devices,organic negative resistance devices,molecular circuit components and ultra-micro-chip, ultra-high density information records technology,and so on.Now,the main synthetic methods of polyaryls were cross-coupling reaction.Thirty-nine novel polyarylenes were synthesized using Suzuki cross-coupling reaction and Sonogashira cross-coupling reaction catalyzed by palladium.Their structures were characterized by IR,NMR,EA and HRMS.The ultraviolet absorption spectra and fluorescence spectra were investigated and the relationship between molecular structure and spectra properties were studied.The thermal properties were tested by thermo-gravimetric analysis（TGA） and the electrochemical properties were investigated by cyclic voltammetry（CV）.The geometric molecular structures were calculated by the software of Gaussian 03 and the corresponding HOMO and LUMO energies were optimized using the density functional theory（DFT） with correlation functional（B3LYP） and the 3-21G basis set.Seventeen novel unsymmetrical terphenyls with nitro group and methylthio group were prepared in good yields by regio-selective double Suzuki cross-coupling reaction which employed Pd（PPh₃）₄ as catalyzer,K₂CO₃ as base and 1,2-dimethoxyethane （DME） as solvent.4-Bromo-1-iodo-2-nitrobenzene react with 4-（methylthio）phenylboronic acid to give single cross-coupling product of （4’-bromo-2’-nitrobiphenyl-4-yl）（methyl） sulfane（3） in high yields,which then reacted with various boronic acids to give unsymmetrical terphenyls of（4a-q）.The ultraviolet absorption and fluorescence properties of these compounds were recorded in CHCl₃.It was found that UV-vis maximal absorption spectra were in the range of 241～318 nm.Theλ_abs^max of 4"-formyl-4-methylthio-2’-nitro- 1,1 ’,4’,1"-terphenyl（4j） was 299 nm and gave a larger red shift than other unsymmetrical terphenyls. Introducing heterocycles（such as thiophene,benzothiophene） showed a large red-shifted absorption compared with unsymmetrical terphenyls.The largest red shift (λ_abs^max = 318 nm) occurred when benzothiophene is introduced to the compounds. These compounds showed good thermal stabilities（＞200℃） as determined by thermo-gravimetric analysis（TGA）.From the figure of cyclic voltarnmetry（CV） we can see that the compounds show two obvious reduction curve and the first reduction curve（reduction potential is -1.22 V） is quasi-reversible.Four novel functional symmetrical oligophenylenes（7a-d） are prepared by Pd（PPh₃）₄ catalyzed double Suzuki cross-coupling reaction from 1,4-bis（4,4,5, 5-tetramethyl-1,3,2-dioxaborolan-2-yl）benzene and substituted 4-bromo-2-nitrobiphenyls（6a-d） in DME with K₂CO₃ as base in 44-75%yields. Four novel functional symmetrical oligoarylenes bearing heteroaryl group（9a-d） are prepared by Pd（PPh₃）₄ catalyzed double Suzuki cross-coupling reaction from 2, 5-bis（4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl）thiophene and substituted 4-bromo-2-nitrobiphenyls in 1,4-dioxane with Caesium fluoride（CsF） as base in 30-80%yields.Substituted groups had a great effect on spectral properties.It was found that UV-vis maximal absorption spectra of 7a-d were in the range of 295～307 nm.Introducing electron donating group caused bathochromic shift of the absorption maximum and the sequence were H（7a）＜Et（7b）＜OMe（7c）＜SMe（7d）.The UV-vis maximal absorption spectra of 9a-d were in the range of 343～348 nm.Introducing electron donating group also caused bathochromic shift of the absorption maximum and the sequence were H（ga）＜Et（9b）＜OMe（9c）≈SMe（9d）.Introducing heterocycles caused bathochromie shift compared maximal absorption spectra of 7a-d with 9a-d. These compounds show good thermal stabilities as determined by TGA and the temperature of losing 5%weight is above 200℃.Cyclic voltammetry（CV） of the synthesized compounds show two obvious reduction curve and the first reduction curve（reduction potential is -1.22 V） is quasi-reversible.Fourteen novel OPEs derivatives are prepared by convergent synthetic methodologies that are based on Suzuki and Sonogashira cross-coupling reaction for aryl-aryl and aryl-ethynyl bond formations.Firstly, （（4-bromo-2-nitrophenyl）ethynyl）trimethylsilane（10） reacted with substituted phenylboronic acid to furnish compounds 11a-m.Reactions was carried out using tetrakis（triphenylphosphine） palladium（0） as catalyst and potassium carbonate（K₂CO₃） as base in 1,2-dimethoxyethane（DME） and H₂O at reflux temperature.Then compounds 11a-m were desilylated using tetrabutylammonium fluoride（TBAF） to furnish the terminal alkynes 12a-m.Secondly,OPEs derivatives 14a-m can readily be achieved by reaction of the corresponding terminal alkynes 12a-m with S-4-iodophenyl ethanethioate（13） using palladium catalyzed Sonogashira cross coupling reaction.Reactions was carried out using tris（dibenzylideneacetone）dipalladium（0） as catalyst,copper（Ⅰ） iodide as co-catalyst and triphenyl phosphine as ligand with N,N-diisopropylethylamine as base.The synthetic route of 17 was similar to 14a-m.It was found that UV-vis maximal absorption spectra of 14a-m and 17 were in the range of 304～321 nm.Introducing substituted groups both electron-donating（R= F,CF₃,C1,CN,acetyl,formyl,vinyl） and electron-withdraw groups（R= methoxy,thiomethyl,ethyl,2,5-dimethoxy） caused bathochromic shift except 14a（R=2,3-dimethoxy） which caused hypsochromic shift.It was found that the largest UV-vis maximal absorption wavelength was 321 nm when R was methylthio group.These compounds show good thermal stabilities as determined by TGA and the temperature of losing 5%weight is above 200℃.Cyclic voltammetry（CV） of the synthesized compounds show two obvious reduction curve and the first reduction curve（reduction potential is -1.10 V） is quasi-reversible.更多还原