Upper Excited State Photochemistry:  Solution and Gas Phase Photochemistry and Photophysics of 2- and 3-Cyclopropylindene<sup>1</sup>

Waugh, Tim; Morrison, Harry

doi:10.1021/ja981397y

Cited by 4 publications

(2 citation statements)

References 52 publications

(54 reference statements)

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“…They can proceed along different routes because in the gas phase the high-energy electronic and vibrational states can live longer without rapid solvent-induced radiationless deactivation. Particularly, the very distinct differences between absorption and excitation spectra and also the latter spectra recorded at different wavelengths were observed for alkylindenes and dihydronaphthalenes . The effects of high-energy excitation can be found in these reactions on the condition that their rates compete with the IC relaxations to S 1 state.…”

Section: Photochemistry From S N (Or From S1 M ) Statesmentioning

confidence: 92%

Breaking the Kasha Rule for More Efficient Photochemistry

2017

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This paper provides a systematic review and analysis of different phenomena that violate a basic principle, Kasha's rule, when applied to photochemical reactions. In contrast to the classical route of ultrafast transition to the lowest energy excited state and photochemical reaction starting therein, in some cases, these reactions proceed directly from high-energy excited states. Nowadays, this phenomenon can be observed for a number of major types of excited-state reactions: harvesting product via intersystem crossing; photoisomerizations; bond-breaking; and electron, proton, and energy transfers. We show that specific conditions for their observation are determined by kinetic factors. They should be among the fastest reactions in studied systems, competing with vibrational relaxation and radiative or nonradiative processes occurring in upper excited states. The anti-Kasha effects, which provide an important element that sheds light on the mechanisms of excited-state transformations, open new possibilities of selective control of these reactions for a variety of practical applications. Efficient utilization of excess electronic energy should enhance performance in the systems of artificial photosynthesis and photovoltaic devices. The modulation of the reporting signal by the energy of excitation of light should lead to new technologies in optical sensing and imaging.

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Section: Photochemistry From S N (Or From S1 M ) Statesmentioning

confidence: 92%

Breaking the Kasha Rule for More Efficient Photochemistry

2017

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“…Indene, however, is characterised by a poor fluorescence signal (f around 0.005), because its excited states are described as biradicals. [25] Moreover, high level computational studies have simulated the potential energy curve of the excited state looking for conical intersections between S 1 and S 0 to account for the non-radiative processes of indene. [26] They found that the main mechanism involved is a fast and efficient internal conversion process.…”

Section: Fluorene-bodipy Derivativesmentioning

confidence: 99%

Controlling Optical Properties and Function of BODIPY by Using Asymmetric Substitution Effects

Bañuelos¹,

Agarrabeitia²,

García‐Moreno³

et al. 2010

Chemistry A European J

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Asymmetrically substituted BODIPY analogues of the dye PM567 have been synthesised from 2-acylpyrroles and pyrroles that bear indene, fluorene or difluorene units. The type of linkage between the fluorene and the BODIPY core plays an important role in the photophysics of the BODIPY chromophore. Indeed, an aliphatic bridge gives rise to an energy-transfer process between the chromophores, whereas a vinyl spacer allows an electronic interaction between them, leading to a large red shift of the spectral bands. The laser action of the new dyes has been analysed under transversal pumping at 10 Hz repetition rate, in both liquid phase and incorporated into solid polymeric matrices. Lasing efficiencies of up to 40% were reached with high photostabilities with the laser output remaining at the initial level after 1×10(5) pump pulses in the same position of the sample. The laser action of the new dyes outperforms the laser behaviour of commercial dyes that emit in the same spectral region. The replacement of fluorene by indene quenches the fluorescence and laser emission, but allows the development of an iron cation fluorescent sensor.

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Steroids as Molecular Photonic Wires.Z→EOlefin Photoisomerization by Intramolecular Triplet−Triplet Energy Transfer with and without Intervening Olefinic Gates¹

and

Morrison

1999

J. Am. Chem. Soc.

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The steroids 3β-((dimethylphenylsilyl)oxy)-17-(Z)-ethylidene-5α-androstane (1), 3β-((dimethylphenylsilyl)oxy)-17-(Z)-ethylidene-5-androstene (2), 3β-((dimethylphenylsilyl)oxy)-17-(Z)-ethylidene-6-methylene-5α-androstane (3a), and 3α-((dimethylphenylsilyl)oxy)-17-(Z)-ethylidene-6-methylene-5α-androstane (3b) have been prepared. The triplet−triplet excited-state energy transfer (TTET) that occurs from the C3 aryl “donor” group to the C17 ethylidene “acceptor” has been studied in detail at 10 mM steroid concentration. Irradiation with 266 nm light results in Z → E olefin isomerization of the C17 ethylidene group, a consequence of both intra- and interTTET. Φ Z → E = 0.037, 0.018, 0.028, and 0.004 for 1, 2, 3a, and 3b, respectively. Detailed kinetic analyses of these compounds and appropriate models, with and without added olefin quenchers, provide a complete set of rate constants which are determined relative to an assumed energy transfer rate constant to piperylene of 7.0 × 109 M-1 s-1. In particular, k intraTTET for 1 = [1.7 (±0.7)] × 106 s-1. Isomerization at C17 in 2, due to intraTTET, is reduced (83% vs 1) but not completely eliminated by the endocyclic alkene in ring B, which functions as a “triplet gate”. The exocyclic methylene group in 3b is more efficient in gating the intraTTET than it is in 3a (ΦTTET = 0.08 vs 0.71, respectively). This higher level of gating that occurs in 3b is attributed to a much shorter lifetime of the axial DPSO triplet, caused by an efficient through-space intraTTET from the axial DPSO group to the C6 exocyclic olefin.

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Upper Excited State Photochemistry: Solution and Gas Phase Photochemistry and Photophysics of 2- and 3-Cyclopropylindene¹

Cited by 4 publications

References 52 publications

Breaking the Kasha Rule for More Efficient Photochemistry

Breaking the Kasha Rule for More Efficient Photochemistry

Controlling Optical Properties and Function of BODIPY by Using Asymmetric Substitution Effects

Steroids as Molecular Photonic Wires.Z→EOlefin Photoisomerization by Intramolecular Triplet−Triplet Energy Transfer with and without Intervening Olefinic Gates¹

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Upper Excited State Photochemistry: Solution and Gas Phase Photochemistry and Photophysics of 2- and 3-Cyclopropylindene1

Cited by 4 publications

References 52 publications

Breaking the Kasha Rule for More Efficient Photochemistry

Breaking the Kasha Rule for More Efficient Photochemistry

Controlling Optical Properties and Function of BODIPY by Using Asymmetric Substitution Effects

Steroids as Molecular Photonic Wires.Z→EOlefin Photoisomerization by Intramolecular Triplet−Triplet Energy Transfer with and without Intervening Olefinic Gates1

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Product

Resources

About

Upper Excited State Photochemistry: Solution and Gas Phase Photochemistry and Photophysics of 2- and 3-Cyclopropylindene¹

Steroids as Molecular Photonic Wires.Z→EOlefin Photoisomerization by Intramolecular Triplet−Triplet Energy Transfer with and without Intervening Olefinic Gates¹