Tautomers and UV-Induced Photoisomerization of a Strongly Intramolecularly H-Bonded Aromatic Azo-Dye: 1-(Cyclopropyl)diazo-2-naphthol

Duarte, Luís F.; Giuliano, B. M.; Reva, Igor; Fausto, Rui

doi:10.1021/jp405061b

Cited by 21 publications

(29 citation statements)

References 40 publications

(56 reference statements)

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“…This finding is in agreement with the experimental results [29] showing that an efficient internal conversion path to the ground state is opened upon absorption, and that, once the equilibrium condition is restored, a consistent fraction of the CPDNO molecules (84%) is in the enol-form. However, as soon as enough energy is provided for the proton to move towards the nitrogen, at about 1.6 Å, the 1 ππ* state is accessed, and the interconversion to the keto conformer form occurs without any barrier.…”

Section: Resultssupporting

confidence: 92%

Using density based indexes to characterize excited states evolution

et al. 2018

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With the aim of offering new computational tools helping in the description of photochemical reactions and phenomena occurring at the excited state, we present in this work the capability of a density based index (Π) in locating decay channels from higher to lower excited states. The Π index, previously applied to disclose non‐radiative decay channels from the first excited state to the ground state, is very simple in its formulation and can be evaluated, practically with no extra computational cost, and coupled to any quantum method able to provide excited states densities. Indeed, this index relies only on the knowledge of energetics and electron densities of the different electronic states involved in the decay. In the present work, we show the proficiency of the Π index in the general case of decay between excited states by applying it to two model systems well characterized both theoretically and experimentally. In both cases, this descriptor was successful in spotting the regions where excited states are more likely to decay, thus suggesting its potential interest for further application in the design of new compounds. © 2018 Wiley Periodicals, Inc.

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Section: Resultssupporting

confidence: 92%

Using density based indexes to characterize excited states evolution

et al. 2018

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“…However, to the best of our knowledge, direct photoswitching between azo and hydrazone tautomers was found only in 1-(cyclopropyl)diazo-2-naphthol. 37 Irradiation of its azo-enol form with a narrowband source in the near-UV range generates different rotameric and tautomeric azo-enol and keto-hydrazone forms that can be interconverted at different irradiation wavelengths.…”

Section: Introductionmentioning

confidence: 99%

Tautomeric photoswitches: anion-assisted azo/azine-to-hydrazone photochromism

et al. 2019

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“…Finally, we found an interesting phenomenon: the 1 ππ* electronic transition strengthens excited‐state hydrogen‐bonding interaction, whereas it is weakened by the 1 n π* transition. This characteristic could be common for similar intramolecularly hydrogen‐bonded systems 39. 74–76 This work also provides important mechanistic implications for understanding the photophysics and photochemistry of dyes such as Sudan I–IV, Orange II, Ponceau 2R, Ponceau 4R, and azo violet, as they share the same molecular scaffold of 2‐hydroxyazobenzene.…”

Section: Discussionmentioning

confidence: 70%

Computational Photochemistry of the Azobenzene Scaffold of Sudan I and Orange II Dyes: Excited‐State Proton Transfer and Deactivation via Conical Intersections

2015

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We employed the complete active space self-consistent field (CASSCF) and its multistate second-order perturbation (MS-CASPT2) methods to explore the photochemical mechanism of 2-hydroxyazobenzene, the molecular scaffold of Sudan I and Orange II dyes. It was found that the excited-state intramolecular proton transfer (ESIPT) along the bright diabatic (1) ππ* state is barrierless and ultrafast. Along this diabatic (1) ππ* relaxation path, the system can jump to the dark (1) nπ* state via the (1) ππ*/(1) nπ* crossing point. However, ESIPT in this dark state is largely inhibited owing to a sizeable barrier. We also found two deactivation channels that decay (1) ππ* keto and (1) nπ* enol species to the ground state via two energetically accessible S1 /S0 conical intersections. Finally, we encountered an interesting phenomenon in the excited-state hydrogen-bonding strength: it is reinforced in the (1) ππ* state, whereas it is reduced in the (1) nπ* state. The present work sets the stage for understanding the photophysics and photochemistry of Sudan I-IV, Orange II, Ponceau 2R, Ponceau 4R, and azo violet.

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Tautomers and UV-Induced Photoisomerization of a Strongly Intramolecularly H-Bonded Aromatic Azo-Dye: 1-(Cyclopropyl)diazo-2-naphthol

Cited by 21 publications

References 40 publications

Using density based indexes to characterize excited states evolution

Using density based indexes to characterize excited states evolution

Tautomeric photoswitches: anion-assisted azo/azine-to-hydrazone photochromism

Computational Photochemistry of the Azobenzene Scaffold of Sudan I and Orange II Dyes: Excited‐State Proton Transfer and Deactivation via Conical Intersections

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