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Photophysical Properties and Electronic Structure of Zinc(II) Porphyrins Bearing 0-4 meso-Phenyl Substituents: Zinc Porphine to Zinc Tetraphenylporphyrin (ZnTPP).
The Journal of Physical Chemistry A ( IF 2.7 ) Pub Date : 2020-09-14 , DOI: 10.1021/acs.jpca.0c06841 Nikki Cecil M Magdaong 1 , Masahiko Taniguchi 2 , James R Diers 3 , Dariusz M Niedzwiedzki 4, 5 , Christine Kirmaier 1 , Jonathan S Lindsey 2 , David F Bocian 3 , Dewey Holten 1
The Journal of Physical Chemistry A ( IF 2.7 ) Pub Date : 2020-09-14 , DOI: 10.1021/acs.jpca.0c06841 Nikki Cecil M Magdaong 1 , Masahiko Taniguchi 2 , James R Diers 3 , Dariusz M Niedzwiedzki 4, 5 , Christine Kirmaier 1 , Jonathan S Lindsey 2 , David F Bocian 3 , Dewey Holten 1
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Six zinc(II) porphyrins bearing 0–4 meso-phenyl substituents have been examined spectroscopically and theoretically. Comparisons with previously examined free base analogues afford a deep understanding of the electronic and photophysical effects of systematic addition of phenyl groups in porphyrins containing a central zinc(II) ion versus two hydrogen atoms. Trends in the wavelengths and relative intensities of the absorption bands are generally consistent with predictions from time-dependent density functional theory calculations and simulations from Gouterman’s four-orbital model. These trends derive from a preferential effect of the meso-phenyl groups to raise the energy of the highest occupied molecular orbital. The calculations reveal additional insights, such as a progressive increase in oscillator strength in the violet-red (B-Q) absorption manifold with increasing number of phenyls. Progressive addition of 0–4 phenyl substituents to the zinc porphyrins in O2-free toluene engenders a reduction in the measured lifetime of the lowest singlet excited state (2.5–2.1 ns), an increase in the S1 → S0 fluorescence yield (0.022–0.030), a decrease in the yield of S1 → T1 intersystem crossing (0.93–0.88), and an increase in the yield of S1 → S0 internal conversion (0.048–0.090). The derived rate constants for S1 decay reveal significant differences in the photophysical properties of the zinc chelates versus free base forms. The unexpected finding of a larger rate constant for internal conversion for zinc chelates versus free bases is particularly exemplary. Collectively, the findings afford fundamental insights into the photophysical properties and electronic structure of meso-phenylporphyrins, which are widely used as benchmarks for tetrapyrrole-based architectures in solar energy and life sciences research.
中文翻译：
带有0-4中亚苯基取代基的锌（II）卟啉的光物理性质和电子结构：锌卟啉对四苯基卟啉锌（ZnTPP）。
六锌（II）卟啉轴承0-4的内消旋-苯基的取代基已被光谱和理论上检查。与先前检查过的游离碱类似物的比较提供了对在含中心锌（II）离子和两个氢原子的卟啉中系统添加苯基的电子和光物理效应的深入理解。吸收带的波长和相对强度的趋势通常与基于时间的密度泛函理论计算的预测和古特曼四轨道模型的模拟相一致。这些趋势源于内消旋的优先作用-苯基基团提高了最高占据分子轨道的能量。这些计算揭示了更多的见解，例如随着苯基数量的增加，紫红色（BQ）吸收歧管中的振荡器强度逐渐增加。在不含O 2的甲苯中向锌卟啉中逐渐添加0–4个苯基取代基会导致最低单线态激发态（2.5–2.1 ns）的测量寿命缩短，S 1 →S 0荧光产量增加（ 0.022–0.030），S 1 →T 1系统间交叉的产量降低（0.93–0.88）和S 1 →S 0的产量增加内部转换（0.048–0.090）。推导的S 1衰变速率常数表明，螯合锌与游离碱形式的光物理性质存在显着差异。对于螯合锌相对于游离碱而言，内部转化率较大的意外常数的意外发现是特别示例性的。共同地，这些发现得到基本见解光物理性质和电子结构的内消旋-phenylporphyrins，其被广泛地用作在太阳能和生命科学基于四吡咯的体系结构的基准研究。
更新日期：2020-09-24
中文翻译：
带有0-4中亚苯基取代基的锌（II）卟啉的光物理性质和电子结构：锌卟啉对四苯基卟啉锌（ZnTPP）。
六锌（II）卟啉轴承0-4的内消旋-苯基的取代基已被光谱和理论上检查。与先前检查过的游离碱类似物的比较提供了对在含中心锌（II）离子和两个氢原子的卟啉中系统添加苯基的电子和光物理效应的深入理解。吸收带的波长和相对强度的趋势通常与基于时间的密度泛函理论计算的预测和古特曼四轨道模型的模拟相一致。这些趋势源于内消旋的优先作用-苯基基团提高了最高占据分子轨道的能量。这些计算揭示了更多的见解，例如随着苯基数量的增加，紫红色（BQ）吸收歧管中的振荡器强度逐渐增加。在不含O 2的甲苯中向锌卟啉中逐渐添加0–4个苯基取代基会导致最低单线态激发态（2.5–2.1 ns）的测量寿命缩短，S 1 →S 0荧光产量增加（ 0.022–0.030），S 1 →T 1系统间交叉的产量降低（0.93–0.88）和S 1 →S 0的产量增加内部转换（0.048–0.090）。推导的S 1衰变速率常数表明，螯合锌与游离碱形式的光物理性质存在显着差异。对于螯合锌相对于游离碱而言，内部转化率较大的意外常数的意外发现是特别示例性的。共同地，这些发现得到基本见解光物理性质和电子结构的内消旋-phenylporphyrins，其被广泛地用作在太阳能和生命科学基于四吡咯的体系结构的基准研究。
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