Mechanistic studies on the photochromism of [e]-annelated dimethyldihydropyrenes

Sheepwash, Molina A. L.; Ward, Timothy R.; Bandyopadhyay, Subhajit; Mitchell, Reginald H.; Bohne, Cornelia

doi:10.1039/b208952a

Cited by 42 publications

(83 citation statements)

References 28 publications

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“…Ring‐opening quantum yields ( Φ close→open ) were measured by actinometry; that is, by comparing the change in absorption upon irradiation at 578 nm during specific time periods. The values shown by 3 and 4 (1.0×10 −1 and 1.4×10 −1 , respectively) were almost as high as that shown by 5 (9.6×10 −2 , comparable to the reported value6j,k). The value shown by 1 (5.5×10 −3 ) was about one twentieth of that shown by 5 , suggesting that the ring opening was less efficient.…”

Section: Resultssupporting

confidence: 83%

“…The spectrum of 5 shows a low‐energy band (400–600 nm) and two high‐energy bands with hyperfine structures (300–400 nm; Figure 3). 6j,k TD‐DFT (cam‐B3LYP) calculations revealed that all the bands were attributed to the π–π* bands of BzDHP. The low‐energy bands were assigned to the 1 B and 1 A states calculated at 533 and 466 nm, where the main transitions were HOMO–LUMO and HOMO–LUMO+1, respectively.…”

Section: Resultsmentioning

confidence: 99%

“…Photoisomerization of Fc‐conjugated BzDHP derivatives : The photoisomerization of BzDHP ( 5 ) with visible light has been previously reported 6j,k. Herein, we will only look at which valence orbital is responsible for the photoisomerization.…”

Section: Resultsmentioning

confidence: 99%

“…General : 2,7‐Di‐ tert ‐butyl‐ trans ‐12c,12d‐dihydro‐12c,12d‐dimethylbenzo[e]pyrene (BzDHP, 5 ),4j, 6l 4,5‐dibromo‐2,7‐di‐ tert ‐butyl‐ trans ‐12c,12d‐dihydro‐12c,12d‐dimethylbenzo[e]pyrene ( 7 ),4k, 6l 4‐bromo‐2,7‐di‐ tert ‐butyl‐ trans ‐12c,12d‐dihydro‐12c,12d‐dimethylbenzo[e]pyrene ( 8 ),6k tributylstannylethynylferrocene,15 1‐formyl‐1′,2′,3′,4′,5′‐pentamethylferrocene,16 and Pd(PPh 3 ) 4 17 were synthesized according to reported methods. Tetrahydrofuran (THF) (Kanto Chemicals) was distilled over Na–benzophenone under nitrogen.…”

Section: Methodsmentioning

confidence: 99%

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Comparative Study of Photochromic Ferrocene‐Conjugated Dimethyldihydropyrene Derivatives

Muratsugu

Kishida

Sakamoto

et al. 2013

Chemistry A European J

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The photochemical properties and the mixed‐valence state of bis(ferrocenylethynyl)benzodimethyldihydropyrene (1) and other benzodimethyldihydropyrene (BzDHP) derivatives were investigated to understand the reversible photoswitching in the electronic communication of 1. Absorption spectra of 1 were characterized by UV/Vis spectroscopy and calculated by using time‐dependent density functional theory (TD‐DFT), and the d orbitals of the ferrocene (Fc) moieties were shown to contribute to the occupied valence orbitals that were responsible for the photochromic behavior. 1 exhibited reversible photoisomerization in THF; however, photochromic behavior was not observed in dichloromethane. Analysis of redox potentials showed that the mixed‐valence state of 1 was more stable in dichloromethane than in THF. This is consistent with the observation that chemical oxidation led to an intervalence charge‐transfer (IVCT) band between the Fc moieties in the mixed‐valence state of 1 in dichloromethane, whereas such a band was not observed for one‐electron‐oxidized 1 in THF. Bis(pentamethylferrocenylethynyl)benzodimethyldihydropyrene (2) did not show photochromic behavior even in THF. The mixed‐valence state of 2 was much less stable than that of 1 in dichloromethane, and no obvious IVCT band was observed for one‐electron‐oxidized 2 in dichloromethane. The difference in the redox contribution of Fc and pentamethylferrocene (Me5Fc) to BzDHP played an important role for these redox and photochromic behaviors; this was supported by analysis of valence orbital energies from DFT calculations. Designing molecules that connect redox centers through the use of a photochromic linker with a redox potential close to that of the redox centers could constitute a useful approach for the production of photochromic redox‐active metal complexes with strong electronic communication.

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Section: Resultssupporting

confidence: 83%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

See 2 more Smart Citations

Comparative Study of Photochromic Ferrocene‐Conjugated Dimethyldihydropyrene Derivatives

Muratsugu

Kishida

Sakamoto

et al. 2013

Chemistry A European J

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“…Dozens of approaches have been proposed thus far for the various AB reaction cases [8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44]. These methods met with varying success.…”

Section: Introductionmentioning

confidence: 99%

Useful Spectrokinetic Methods for the Investigation of Photochromic and Thermo-Photochromic Spiropyrans

Maafi

2008

Molecules

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This review reports on the main results of a set of kinetic elucidation methods developed by our team over the last few years. Formalisms, procedures and examples to solve all possible AB photochromic and thermophotochromic kinetics are presented. Also, discussions of the operating conditions, the continuous irradiation experiment, the spectrokinetic methods testing with numerical integration methods, and the identifiability/distinguishability problems, are included.

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Excited‐State Topology Modifications of the Dihydroazulene Photoswitch Through Aromaticity

et al. 2019

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The gain and loss of aromaticity plays a key role in organic chemistry and in the prediction of rate-determining steps. Herein, we explore the concept of aromaticity in photoisomerization reactions. Benzannulated derivatives of the dihydroazulene-vinylheptafulvene (DHA-VHF) photoswitch were investigated using transient absorption spectroscopy and timedependent density functional theory to elucidate the effect of built-in aromaticity on the switching properties. We found that benzannulation hampered the switching ability by enhancing an already existing barrier on the excited state surface. This enhancement was found to arise from a significant loss of aromaticity in the DHA-to-VHF transition state on the excited state potential energy surface. The VHF was found to be highly aromatic on the excited state surface, showing a reversal of aromaticity compared to the ground state. The barrier was found to be dependent on the position of benzannulation, since one derivative was found to switch as fast as the nonbenzannulated molecule although with lower efficiency, whereas another derivative completely lost the ability to undergo reversible photoswitching. The findings herein provide novel principles for the design of molecular photoswitches, shedding new light on excited state aromaticity, as previous discussions have mainly considered excited state aromaticity to be beneficial to switching. Our findings show that this view must be reconsidered.[a] Mr.

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Mechanistic studies on the photochromism of [e]-annelated dimethyldihydropyrenes

Abstract: The photochemistry of several photochromic arene [e]-annelated dimethyldihydropyrenes (DHPs) was studied. These compounds have much larger photochemical ring opening quantum yields than the simple DHPs, making them potentially more useful as building blocks for photoswitchable materials.

Cited by 42 publications

References 28 publications

Comparative Study of Photochromic Ferrocene‐Conjugated Dimethyldihydropyrene Derivatives

Comparative Study of Photochromic Ferrocene‐Conjugated Dimethyldihydropyrene Derivatives

Useful Spectrokinetic Methods for the Investigation of Photochromic and Thermo-Photochromic Spiropyrans

Excited‐State Topology Modifications of the Dihydroazulene Photoswitch Through Aromaticity

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