Resonance Raman studies of heterocyclic aromatic compounds showing ultrafast intramolecular proton transfer

Pfeiffer, M.; Lenz, K.; Lau, A.; Elsaesser, Thomas

doi:10.1002/jrs.1250260805

Cited by 38 publications

(38 citation statements)

References 8 publications

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“…and enhanced intensities in combination bands would signal modes central to the exchange process. [55][56][57] We hope to present such an analysis for this and certain members of the SA family in a later publication.…”

Section: Discussionmentioning

confidence: 97%

Ab Initio Molecular Dynamics of Excited-State Intramolecular Proton Transfer around a Three-State Conical Intersection in Malonaldehyde

2005

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Excited-state potential energy surface (PES) characterization is carried out at the CASSCF and MRSDCI levels, followed by ab initio dynamics simulation of excited-state intramolecular proton transfer (ESIPT) on the S2(pipi*) state in malonaldehyde. The proton-transfer transition state lies close to an S2/S1 conical intersection, leading to substantial coupling of proton transfer with electronic relaxation. Proton exchange proceeds freely on S2, but its duration is limited by competition with twisting out of the molecular plane. This rotamerization pathway leads to an intersection of the three lowest singlet states, providing the first detailed report of ab initio dynamics around a three-state intersection (3SI). There is a significant energy barrier to ESIPT on S1, and further pyramidalization of the twisted structure leads to the minimal energy S1/S0 intersection and energetic terminal point of excited-state dynamics. Kinetics and additional mechanistic details of these pathways are discussed. Significant depletion of the spectroscopic state and recovery of the ground state is seen within the first 250 fs after photoexcitation.

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Section: Discussionmentioning

confidence: 97%

Ab Initio Molecular Dynamics of Excited-State Intramolecular Proton Transfer around a Three-State Conical Intersection in Malonaldehyde

2005

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“…Moreover, combination modes of the strongest band below 500 cm 1 and the vibrations at higher wavenumbers could also be observed in two of the systems considered. 18 1-Hydroxy-2-acetonaphthone (HAN) is an extremely photostable intramolecular hydrogen bonded system used in polymer protection. 21 Several spectroscopic studies have been reported in order to discern the photophysics of HAN.…”

Section: Introductionmentioning

confidence: 99%

The excited‐state geometry of 1‐hydroxy‐2‐ acetonaphthone: a resonance Raman and quantum chemical study

Szeghalmi

Engel

Zgierski

et al. 2006

J Raman Spectroscopy

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1-Hydroxy-2-acetonaphthone (HAN), an intramolecular proton transfer system, was investigated in the present study by means of quantum chemical calculations and resonance Raman spectroscopy. To determine the Franck-Condon parameters, a time-dependent approach for the analysis of the resonance Raman spectra was applied. About 18 vibrational modes were found to be involved in the initial dynamics of HAN upon photo excitation. Moreover, the excited-state geometry of HAN was optimized at the CASSCF level of theory and the displacement parameters were determined. A very good agreement between the theoretical and experimentally derived parameters was obtained. The vibrations with the highest displacements correspond to stretching and in-plane deformation modes of the naphthalene ring and the conjugated carbonyl group, while the OH stretching mode exhibits no observable enhancement. Hence, a general molecular rearrangement takes place upon photo excitation, where the intramolecular oxygen-oxygen distance reduces corresponding to a redistribution of the electron density.

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“…These three bands involve CÀ C stretching modes and notably the biaryl central CÀC bond. [21] The displacement of the above Raman lines is attributed to the electronic reorganization of the molecule, as expected to occur during the tautomerization.…”

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confidence: 95%

In Situ Incorporation of 2‐(2‐Hydroxyphenyl)benzothiazole within FAU Colloidal Crystals

Mintova¹,

Waele

Schmidhammer

et al. 2003

Angew Chem Int Ed

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Novel nanostructured functional materials can be constructed by encapsulation of optically active guests in microporous hosts. Incorporation of organic molecules inside the cages of zeolites permits the control of both their molecular and optical properties. To achieve this goal, it is essential to accommodate specific molecules within the voids of the zeolite structures and to create nanosized assemblies such as thin films, layers, or monolith structures for specific applications. Generally, the microporous materials used for the preparation of nanostructured assemblies are synthesized in colloidal form from clear aluminosilicate or aluminophosphate solutions, which results in a mean particle size in the range of about 20-600 nm. [1][2][3][4][5] Nanoscale organosilicate clusters in the precursor solutions used for the synthesis of colloidal zeolites have been observed with different techniques. [6][7][8][9][10] Nanoscale amorphous gel particles (with a size of 5-50 nm) are formed in the precursor solutions before longrange crystalline order is established. [3,4] Based on these insights, the encapsulation of additional organic molecules in the crystalline internal voids of zeolite structures should be possible by direct incorporation from the precursor colloidal solutions. Moreover, colloidal molecular sieves with particle sizes in the nanometer range can have high colloidal stability in different solvents with respect to further agglomeration and sedimentation. These features make the encapsulation of functional optical molecules in nanoscale zeolite suspensions an attractive synthetic goal. Such suspensions are 1) promising systems for optical investigations of host-guest interactions, and 2) interesting precursors for the construction of nanostructured assemblies such as optical coatings and selective chemical sensors. The application of nanosized zeolites opens up possibilities for the preparation of homogeneous zeolite films on many different supports, as well as inert substrates, by efficient spin-coating of stable colloidal solutions. The generation of defined porous nanocrystals with encapsulated, optically active guests provides a route to twodimensional functional constructs for further applications, for example, in the area of optical sensors.Molecules with excited-state intramolecular proton-transfer (ESIPT) properties constitute a promising family of potential guests in functionalized zeolite materials for applications in the area of UV filtering, [11] sensing, [12] or even molecular switching. Among the different ESIPT systems, the HBX dyes (X = S,O or NH for 2-(2-hydroxyphenyl)benzothiazole (HBT), -benzooxazole, or -benzimidazole systems, respectively) have received particular attention, and their properties are being extensively studied regarding their steady-state [13][14][15][16][17][18] and time-dependent behavior.[19] The photophysical properties of these compounds are strongly dependent on the polar and protic character of the solvent that influences the relative stability of different tautom...

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Resonance Raman studies of heterocyclic aromatic compounds showing ultrafast intramolecular proton transfer

Cited by 38 publications

References 8 publications

Ab Initio Molecular Dynamics of Excited-State Intramolecular Proton Transfer around a Three-State Conical Intersection in Malonaldehyde

Ab Initio Molecular Dynamics of Excited-State Intramolecular Proton Transfer around a Three-State Conical Intersection in Malonaldehyde

The excited‐state geometry of 1‐hydroxy‐2‐ acetonaphthone: a resonance Raman and quantum chemical study

In Situ Incorporation of 2‐(2‐Hydroxyphenyl)benzothiazole within FAU Colloidal Crystals

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