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首页> 外文学位 >UV-Vis and MCD Spectroscopy and TDDFT investigations into N-Confused porphyrins and properties of mono-functionalized tetraferrocenyl porphyrins in solution and on a gold surface: Assessment of the influencing factors for photoelectrochemical applications.
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UV-Vis and MCD Spectroscopy and TDDFT investigations into N-Confused porphyrins and properties of mono-functionalized tetraferrocenyl porphyrins in solution and on a gold surface: Assessment of the influencing factors for photoelectrochemical applications.

机译：紫外-可见光谱和MCD光谱学和TDDFT研究N混淆的卟啉以及溶液中和金表面上的单官能化四茂铁卟啉的性质：光电化学应用的影响因素评估。

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摘要

N-confused porphyrin (NCP) and its externally methylated variant (MeNCP) were investigated using UV-visible and magnetic circular dichroism (MCD) spectroscopies. In addition to evaluating the spectroscopy of the neutral compounds, the acid/base chemistry of these macrocycles was examined by the same methods. NCP exhibits two tautomeric states depending on the polarity of the solvent, and their protonation/deprotonation chemistries also differ depending on solvent polarity. DFT and TDDFT calculations were employed to evaluate the observed spectroscopic changes. Using both experimental and calculated results, we were able to determine the sites of protonation/deprotonation for both tautomeric forms of NCP. Inspection of the MCD Faraday B terms for all of the macrocycles presented in this report showed that the DeltaHOMO > DeltaLUMO condition is maintained in all cases and these observations were in good agreement with the DFT calculations.;Various methylated N-confused tetraphenylporphyrins (MeNCTPP) were investigated using UV-Vis and magnetic circular dicrhoism (MCD) spectroscopy in polar and apolar solvents as well as the protonation and deprotonation of the compounds. The MeNCTPPs were also investigated using time-dependent density functional theory (TDDFT) methods in the gas phase. Experimentally, the MCD spectra showed that all the molecules investigated had transitions with the DeltaHOMO > DeltaLUMO. TDDFT results confirmed these energy gaps. TDDFT calculations also showed that nearly all low energy transitions were from the HOMO to the LUMO and LUMO+1, except in the case of 2c, 5a, and 5c. Otherwise, results show that the addition of a methyl group to the N-confused tautomer of tetraphenylporphyrin effectively regulates the proton tautomerization of the N-confused tautomer. MeNCTPPs are unaffected by the polarizability of the solvent.;Two unsymmetric meso-tetraferrocenyl-containing porphyrins of general formula HH2Fc3Fc(COR)P [Fc = ferrocenyl, R = -CH 3 or --(CH2)5Br, P = porphyrin(2-)] have been prepared and characterized by variety of spectroscopic methods, while their redox properties were investigated using cyclic voltammetry (CV) and differential pulse voltammetry (DPV) approaches. Spectroscopic signature of the mixed-valence [H2Fc3Fc(COR)P]n+ (n = 1, 3) were investigated using spectroelectrochemical as well as chemical oxidation methods and corroborated with DFT and TDDFT calculations. Inter-valence charge-transfer (IVCT) transitions in [HH2Fc3Fc(COR)P] + were analyzed using band deconvolution analysis in the borders of Hush model. The resulting data from the mixed-valence [HH2Fc 3Fc(COR)P]+ derivatives matched very closely to the previously reported MTFcP and metal-free poly(ferrocenyl)porphyrins complexes and were assigned as Robin and Day Class II mixed-valence compounds. Following previous results indicating the ability of gold supported TFcP monolayers in photo-catalytic reduction of dioxygen, self-assembled monolayers (SAMs) of a thioacetyl derivative (HH2Fc3Fc(CO(CH2)5SCOCH3 )P) were also prepared and characterized using UV-vis spectroscopy and CV methods. Photoelectrochemical properties of SAMs in different electrolyte systems were investigated by electrochemical techniques and photocurrent generation experiments, showing that the choice of electrolyte is critical for efficiency of redox-active SAMs.
机译：使用紫外可见和磁性圆二色性（MCD）光谱学研究了N混淆卟啉（NCP）及其外部甲基化变体（MeNCP）。除了评估中性化合物的光谱外，还通过相同的方法检查了这些大环的酸/碱化学性质。 NCP根据溶剂的极性显示两个互变异构状态，并且它们的质子化/去质子化化学也根据溶剂的极性而不同。使用DFT和TDDFT计算来评估观察到的光谱变化。使用实验和计算结果，我们能够确定NCP的两种互变异构形式的质子化/去质子化位点。对本报告中介绍的所有大环的MCD法拉第B术语的检查表明，在所有情况下都保持DeltaHOMO> DeltaLUMO条件，并且这些观察结果与DFT计算结果非常吻合;各种甲基化的N混淆的四苯基卟啉（MeNCTPP）在极性和非极性溶剂中使用UV-Vis和磁圆二色性（MCD）光谱以及化合物的质子化和去质子化进行了研究。 MeNCTPPs还使用时变密度泛函理论（TDDFT）方法在气相中进行了研究。通过实验，MCD光谱表明，所有研究的分子均具有DeltaHOMO> DeltaLUMO的跃迁。 TDDFT结果证实了这些能隙。 TDDFT计算还表明，除了2c，5a和5c以外，几乎所有的低能跃迁都是从HOMO到LUMO和LUMO + 1。否则，结果表明，向四苯基卟啉的N-混淆的互变异构体中添加甲基可有效调节N-混淆的互变异构体的质子互变异构。 MeNCTPP不受溶剂极化性的影响;两种不对称的含内四氟二茂铁基的卟啉，通式为HH2Fc3Fc（COR）P [Fc =二茂铁基，R = -CH 3或-（CH2）5Br，P =卟啉（2 -）]已通过多种光谱方法制备和表征，同时使用循环伏安法（CV）和差分脉冲伏安法（DPV）方法研究了它们的氧化还原特性。使用光谱电化学和化学氧化方法研究了混合价[H2Fc3Fc（COR）P] n +（n = 1，3）的光谱特征，并通过DFT和TDDFT计算得到了证实。使用Hush模型边界中的能带反卷积分析法分析了[HH2Fc3Fc（COR）P] +中的价间电荷转移（IVCT）跃迁。来自混合价[HH2Fc 3Fc（COR）P] +衍生物的结果数据与先前报道的MTFcP和不含金属的聚二茂铁卟啉配合物非常匹配，并被指定为Robin和Day Class II混合价化合物。根据先前的结果表明金负载的TFcP单层在双氧光催化还原中的能力，还制备了硫代乙酰基衍生物（HH2Fc3Fc（CO（CH2）5SCOCH3）P）的自组装单层（SAMs）并进行了表征光谱和CV方法。通过电化学技术和光电流产生实验研究了不同电解质体系中SAMs的光电化学性质，表明电解质的选择对于氧化还原活性SAMs的效率至关重要。

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  • 作者

    Erickson, Nathan Robert.;

  • 作者单位

    University of Minnesota.;

  • 授予单位 University of Minnesota.;
  • 学科 Chemistry.;Organic chemistry.;Physical chemistry.
  • 学位 M.S.
  • 年度 2014
  • 页码 179 p.
  • 总页数 179
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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