【作者】 王孟舟；

【导师】 孙成林； 里佐威；

【作者基本信息】 吉林大学 ， 理论物理， 2014， 博士

【摘要】 络合物作为一种常见的化合物，在日常生活、工业生产、生命科学等领域，都有着广泛的应用。两个电荷密度差别比较大的分子、原子或基团，可以通过电荷转移相互作用结合在一起，形成电荷转移络合物。电荷转移相互作用可以引起分子溶解性、稳定性、体系粘度、摩尔体积等多方面的变化，利用这些性质的改变，电荷转移络合物被应用于分析化学、生物医药、半导体学等科研领域。线性多烯分子由于其特有的性能使其在光电器件等领域中具有广泛的应用。类胡萝卜素作为一种特殊的线性多烯分子，广泛的存在于自然界中。β胡萝卜素、角黄素和番茄红素是类胡萝卜素中研究最多的三种类胡萝卜素。在光合作用中，β胡萝卜素具有光能采集、转移能量、淬灭单态氧等功能，使其在物理学、化学和生物学中成为研究的热点之一。β胡萝卜素分子中含9个共轭碳碳双键，在514.5nm激光激发下有很大的拉曼活性，拉曼散射截面可达10-23—10-20cm2mol-1Sr-1。碘与β胡萝卜素在1,2-二氯乙烷溶液混合，β胡萝卜素分子发生异构化，生成电荷转移络合物。在紫外-可见吸收光谱中，可以观察到随着电荷转移络合物的形成，β胡萝卜素在460nm处的峰逐渐消失，在1000nm处出现了β胡萝卜素与碘络合物的新峰。用514.5nm激光做激发光源，测量了溶液中未生成络合物的β胡萝卜素的共振拉曼光谱。本文利用共振拉曼光谱、可见吸收光谱技术、依据分子光谱相关理论，主要研究了：利用Teflon-AF光纤测量了水中β胡萝卜素的共振拉曼光谱；测量了293K—83K含碘1,2二氯乙烷溶液中的β胡萝卜素的共振拉曼光谱，得出温度变化对CC键基频、拉曼散射截面、和频（倍频）和线宽的影响，并与不含碘的β胡萝卜素做比较；测量了极性溶剂1,2-二氯乙烷含碘溶液中的β胡萝卜素的紫外-可见吸收光谱和拉曼光谱，得出碘浓度的变化对CC键基频υ1、υ2拉曼散射截面、线宽以及电子-声子耦合系数的的影响，取得了以下创新性成果：（1）利用Teflon-AF光纤，研究了水中β胡萝卜素的拉曼散射截面。结果表明，随着浓度的降低，β胡萝卜素分子C=C，C-C键拉曼散射截面大幅增加，可达1.22×10-21mol-1Sr-1。其机理主要是随β胡萝卜素在水中浓度降低，其分子间作用力减小，使其分子结构有序性增加，有效共轭长度增加，拉曼活性大幅度提高，即拉曼散射截面增加。（2）利用变换温度法，测量了293K—83K条件下极性溶剂1,2-二氯乙烷-碘溶液中的β胡萝卜素的共振拉曼光谱。结果表明，在293K—213K的液态温区和188K—83K的固态温区，随着温度的下降，β胡萝卜素的CC键基频拉曼散射截面增加，在液态到固态相变期间减小。CC键和频（倍频）与基频光谱强度比随温度降低而增加，相变期间比值更大。CC键基频的线宽随着温度的降低逐渐减小，相变期间反常。与不含碘的1,2二氯乙烷溶液中β胡萝卜素拉曼光谱相比较，含碘溶液的β胡萝卜素CC键拉曼散射截面减小，线宽宽度增加。这是由于温度降低，热无序减弱，分子有序性增强，π电子离域扩展，π电子-声子耦合对CC键同步振动调节增强，使相干弱阻尼电子—晶格振动增强，拉曼活性增加，共振拉曼效应提高，拉曼散射截面增大，线宽变窄；溶液相变期间反常。在有络合物生成的溶液中，受络合物不稳定的影响，β胡萝卜素分子有序性下降，拉曼散射截面减小，线宽增加。（3）利用变换浓度法，测量了室温(20℃)条件下极性溶剂1,2-二氯乙烷-碘溶液中的β胡萝卜素紫外-可见吸收光谱和拉曼光谱。结果表明,生成络合物的β胡萝卜素在460nm处的紫外-可见吸收峰消失,并在1000nm处出现β胡萝卜素与碘形成络合物的吸收峰,致使514.5nm激光激发时察觉不到络合物中β胡萝卜素离子CC键的共振拉曼光谱。随着络合物浓度的增加，溶液中没有形成络合物的β胡萝卜素CC键拉曼散射截面减小,拉曼光谱线宽增加,β胡萝卜素分子吸收峰发生蓝移，黄琨因子逐渐增大，π电子-声子耦合系数增加。这是由于随着溶液中络合物浓度增大,溶液的混乱程度增加,热无序增大, β胡萝卜素结构有序性降低,电子离域减小,有效共轭长度减小,相干弱阻尼电子晶格振动减弱而导致的。综上所述，本论文通过共振拉曼光谱与紫外-可见吸收光谱相结合，用改变溶液中络合物的浓度和改变温度的方法研究了络合物形成对β-胡萝卜素分子光谱的影响，为认识络合物形成对β胡萝卜素结构与光学性质的影响及电子-声子相互作用规律研究提供了新思路，也为线性多烯分子在溶液中的结构和性质的研究提供了参考资料。更多还原

【Abstract】 Complex has a wide range of applications as a kind of common compounds inthe daily life, industrial production, life science and other fields. Two molecules,atoms or groups with a large charge density difference can form a charge transfercomplex by the charge transfer interaction. The charge transfer complex was used inanalytical chemistry, biological medicine, semiconductor science to learn scientificresearch fields due to charge transfer interactions leading to changes in molecularsolubility, stability, viscosity, molar volume.Linear polyene has a wide application in the field of optoelectronic devices dueto its unique property. Carotenoids exist in nature widely as a special kind of linearpolyene molecules. β-carotene, lycopene and canthaxanthin are the most widelystudied of the three ones of carotenoids. β–carotene is in use with light energycollection, energy transfer and quenching oxygen during photosynthesis, which makesits one of research hot spot in physics, chemistry and biology.All-trans-β-carotene is a linear polyene molecule with9conjugated doublebonds, the RSCS of its CC bonds can reach10-23—10-20cm2mol-1Sr-1at514.5nmexcitation from an Ar ion laser. It makes the charge transfer complex form that β–carotene becomes molecular isomerization and iodine is attached to the conjugateddouble bond. The absorption spectra show that the visible absorption band of thecomplex formed by all-trans-β-carotene and iodine shifts from460nm to1000nm. Inthis paper, we measured the resonance Raman spectra of the all-trans-β-carotenehaving not formed the complex.We use the resonance Raman and visible absorption spectroscopy technology toresearch following work according to the theory of molecular spectrum. The Ramanscattering cross section of beta carotene has been studied in water by Teflon-AFfiber. The resonance Raman spectra of the fundamental, combination, and secondharmonic modes around the C–C and C=C stretches of all-trans-β-carotene in1,2-dichloroethane with iodine solution are obtained in the range of293K to83K. We got the range of Raman scattering cross section of CC bonds of all-trans-β-carotenenot formed in complex, the ratio between the Raman spectral intensities of thecombinations (overtones), its full bandwidth broadens at different temperatures,compared with the one without iodine.The UV-vis absorption and resonance Ramanspectra of all-trans-β-carotene in polar solvent1,2-dichloroethane with iodine weremeasured at293K. We got the range of Raman scattering cross section of CC bondsof all-trans-β-carotene not formed in complex, its full bandwidth broadens andelectron-phonon parameter with different concentrations. We got the followinginnovative achievements.(1) The Raman scattering cross section of β-carotene has been studied in waterby Teflon-AF fiber. It shows that the RSCS of its C=C and C-C bonds can reach10-23—10-20cm2mol-1Sr-1during the reducing of concentration. Its mechanism is asthe concentration of β-carotene is reduced in the water, the Intermolecular Forcesdecrease, which makes its molecular structure order and effective conjugation lengthincrease, the Raman active is sharply higher, the Raman scattering cross section ofβ-carotene increases.(2) The resonance Raman spectra of the fundamental, combination, and secondharmonic modes around the C–C and C=C stretches of all-trans-β-carotene in1,2-dichloroethane with iodine solution are obtained in the range of293K to83K. TheRaman scattering cross section of the fundamentals in the liquid (293K to213K) andsolid phases (188K to83K) generally increases as the temperature decreases, exceptfor the liquid-solid phase transition, which exhibits a decreasing trend; The ratiobetween the Raman spectral intensities of the combinations (overtones) and thefundamentals of CC bonds increases with decreasing temperature, especially in theliquid-solid phase transition. The Raman bandwidths of the CC bonds graduallybecome narrow, but then reach a maximum in the phase transition. The Ramanscattering cross section of the CC bonds in solution with iodine decreases and theRaman bandwidths broaden, compared with the one without iodine. This phenomenonis attributed to the enhanced coherent weakly damped electron-lattice vibrationsassociated with the increase in the structural order. Resonant effects also lead to a high Raman intensity for the CC bonds in fundamental modes. The decreasedstructural order induces the RSCS of the fundamental modes to decrease rapidlyduring the liquid-solid phase transition. However, the strong electron-phononcoupling causes the relative Raman intensity of the combination and harmonic modesto rapidly increase as the temperature decreases. The bandwidths of CC bondsbecome narrow while abnormal in phase transition period. The molecular structuralorder decreases, the RSCS of CC bonds decreases, the bandwidth become broaden asthe complexes are formed in the solution.(3) The Uv-vis absorption and resonance Raman spectra of all-trans-β-carotenein polar solvent1,2-dichloroethane with iodine were measured at293K. The resultsindicated that the absorption peak of all-trans-β-carotene in the complex disappears at460nm and a new peak of the complex formed by all-trans-β-carotene and iodine isfound at1000nm, so that the all-trans-β-carotene within the complex cannot producethe resonance Raman spectrum by514.5nm excitation laser. The Raman scatteringcross section of CC bonds of all-trans-β-carotene not formed in complex decreases, itsfull bandwidth broadens and electron-phonon parameter increases with the increasingconcentration of the complex, because when the concentration of the complexincreases the disorder increases in the solution and the molecular structural orderdecreases.In summary, we analyse the effect of complex formation on the resonance ramanspectra of all-trans-β-carotene in iodine solution. The mechanism of generatingoptical phenomenon and the interactions between intramolecular and intermolecularhave been grasped. It has theoretical value for understanding the effect of complexformation on the structure and optical property of all-trans-β-carotene and theinfluence of electronic-phonon interaction, provides reference information in thestudy of the linear polyene as well.更多还原