The photophysical properties of expanded porphyrins: relationships between aromaticity, molecular geometry and non-linear optical properties

Lim, Jong Min; Yoon, Zin Seok; Shin, Jae Yoon; Kim, Kil Suk; Yoon, Min Chul; Kim, Dongho

doi:10.1039/b810718a

Cited by 147 publications

(120 citation statements)

References 107 publications

(84 reference statements)

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“…[19] Thus, the conformational control of expanded porphyrins still remains important not only for control of their aromaticity, but also for exploration of novel functions.…”

Section: Introductionmentioning

confidence: 99%

Solvent‐Dependent Aromatic versus Antiaromatic Conformational Switching in meso‐(Heptakis)pentafluorophenyl [32]Heptaphyrin

Yoon

Shin

Lim

et al. 2011

Chemistry A European J

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We have investigated conformational switching dynamics of meso-heptakis(pentafluorophenyl) [32]heptaphyrin(1.1.1.1.1.1.1) in various solvents using steady-state, time-resolved, and temperature-dependent spectroscopy. Absorption and fluorescence spectra of [32]heptaphyrin are quite sensitive to solvent environments. In nonpolar toluene, the antiaromatic figure-of-eight conformation is dominant, as seen in the X-ray crystallography, based on broad and weak absorption bands without any fluorescence and moderate paratropic ring current. On the other hand, a well-resolved sharp absorption spectrum, strong fluorescence, and diatropic ring current in the 1H NMR spectrum in slightly polar THF indicate that most of [32]heptaphyrin molecules take significantly distorted Möbius conformation with aromatic character. By using transient absorption (TA) spectroscopy, the lowest singlet excited-state lifetimes have been revealed to decay biexponentially with the time constants of 5 and 65 ps for figure-of-eight and Möbius conformations, respectively. Based on these results along with vertical excitation energy calculations, we are able to assign two conformers as Hückel antiaromatic and Möbius aromatic species, respectively; it shoulf be noted that the aromaticity/antiaromaticity does not change with temperature variation. Interestingly, in moderately polar solvent, ethyl ether, we find out that these two conformational isomers coexist with a dynamic equilibrium, as revealed by excitation-wavelength-dependent TA, temperature-dependent absorption and 1H NMR spectra. Through our findings, we have demonstrated that the conformational switching dynamics between Hckel antiaromatic and Möbius aromatic conformers in [32]heptaphyrin(1.1.1.1.1.1.1) are strongly affected by solvent medium as well as temperature.

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“…[19] Thus, the conformational control of expanded porphyrins still remains important not only for control of their aromaticity, but also for exploration of novel functions.…”

Section: Introductionmentioning

confidence: 99%

Solvent‐Dependent Aromatic versus Antiaromatic Conformational Switching in meso‐(Heptakis)pentafluorophenyl [32]Heptaphyrin

Yoon

Shin

Lim

et al. 2011

Chemistry A European J

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“…In addition, their absorption may be extended into the near infrared by suitable chemical engineering. [5][6][7][8][9][10][11][12][13][14] The properties and effects of these infrared-absorbing phthalocyanines are diverse and cover many important hi-tech applications, including photodynamic therapy, optical data storage, reverse saturable absorbers and solar screens. The majority of these applications exploit the unique optical properties of phthalocyanines, and thus a variety of spectroscopic techniques such as UV-vis spectroscopy, magnetic circular dichroism (MCD), and fluorescent as well as time-resolved fluorescent spectroscopy were used in the characterization of the excited states of phthalocyanines and their analogues.…”

Section: Phthalocyaninesmentioning

confidence: 99%

Influence of Exchange-Correlation Functional in the Calculations of Vertical Excitation Energies of Halogenated Copper Phthalocyanines using Time-Dependent Density Functional Theory (TD-DFT)

Lee

2013

Bulletin of the Korean Chemical Society

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The accurate prediction of vertical excitation energies is very important for the development of new materials in the dye and pigment industry. A time-dependent density functional theory (TD-DFT) approach coupled with 22 different exchange-correlation functionals was used for the prediction of vertical excitation energies in the halogenated copper phthalocyanine molecules in order to find the most appropriate functional and to determine the accuracy of the prediction of the absorption wavelength and observed spectral shifts. Among the tested functional, B3LYP functional provides much more accurate vertical excitation energies and UV-vis spectra. Our results clearly provide a benchmark calibration of the TD-DFT method for phthalocyanine based dyes and pigments used in industry.

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“…12 The expanded porphyrins can exchange between the Hückel and Möbius topologies applying small changes in the external conditions (temperature, solvent, redox potential) or in the structure of the ring. The key factors, which will determine their potential use as optical switches are the high values of the NLOP and a) E-mail: miqueltorrentsucarrat@gmail.com.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of the nonlinear optical properties for an expanded porphyrin Hückel-Möbius aromaticity switch

Torrent‐Sucarrat

Anglada²,

Luis³

2012

The Journal of Chemical Physics

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The conformational flexibility of the expanded porphyrins allows them to achieve different topologies with distinct aromaticities and nonlinear optical properties (NLOP). For instance, it is possible to switch between Möbius and Hückel topologies applying only small changes in the external conditions or in the structure of the ring. In this work, we evaluate the electronic and vibrational contributions to static and dynamic NLOP of the Hückel and Möbius conformers of A,D-di-pbenzi[28]hexaphyrin(1.1.1.1.1.1) synthesized by Latos-Grażyński and co-workers [Angew. Chem., Int. Ed. 46, 7869 (2007)]. Calculations are performed at the HF, M052X, and CAM-B3LYP levels using the 6-31G, 6-311G(d), and 6-31+G(d) basis sets. Our results conclude that M052X/6-31G and CAM-B3LYP/6-31G methods provide a correct qualitative description of the electronic and vibrational contributions for the NLOP of expanded porphyrins. The studied systems show high NLOP with large differences between the Möbius and Hückel conformations (around 1 × 10 6 a.u. forγ ). The obtained results indicate that the expanded porphyrins are promising systems to manufacture Hückel-to-Möbius topological switches.

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The photophysical properties of expanded porphyrins: relationships between aromaticity, molecular geometry and non-linear optical properties

Cited by 147 publications

References 107 publications

Solvent‐Dependent Aromatic versus Antiaromatic Conformational Switching in meso‐(Heptakis)pentafluorophenyl [32]Heptaphyrin

Solvent‐Dependent Aromatic versus Antiaromatic Conformational Switching in meso‐(Heptakis)pentafluorophenyl [32]Heptaphyrin

Influence of Exchange-Correlation Functional in the Calculations of Vertical Excitation Energies of Halogenated Copper Phthalocyanines using Time-Dependent Density Functional Theory (TD-DFT)

Evaluation of the nonlinear optical properties for an expanded porphyrin Hückel-Möbius aromaticity switch

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