Solute–solvent interaction in the photoinduced tautomerization of 7-azaindole in various alcohols and in mixtures of cyclohexane and ethanol

Konijnenberg, Jan; Huizer, A. Herbert; Varma, Cyril A. G. O.

doi:10.1039/f29888401163

Cited by 76 publications

(98 citation statements)

References 4 publications

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“…The mechanism of solvent involvement in the excited‐state tautomerization of 7AI in water and alcohols has attracted considerable attention 4. 6, 9–12 In particular, the two‐step model described in Scheme has been discussed widely 9–11. The first step is solvent reorganization ( k r ) about the normal ( N ) 7AI molecule to form a cyclic H‐bonded 1:1 7AI/solvent complex ( Nb ), and the second step is intrinsic proton transfer ( k pt ) relayed by the complexed protic solvent molecule to give the tautomer ( T ).…”

Section: Methodsmentioning

confidence: 99%

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Asymmetric Double Proton Transfer of Excited 1:1 7‐Azaindole/Alcohol Complexes with Anomalously Large and Temperature‐Independent Kinetic Isotope Effects

et al. 2004

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Bridging alcohols, tunneling protons: The intrinsic proton‐transfer dynamics of cyclic H‐bonded 1:1 7‐azaindole/alcohol complexes in n‐alkanes has been investigated at the lowest‐lying excited singlet state with variation of alcohol, solvent, isotope, and temperature by using static and time‐resolved spectroscopy. The proton transfer occurs asymmetrically, and the rate is governed by tunneling although it is assisted by heavy‐atom motions.

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Section: Methodsmentioning

confidence: 99%

“…In water and alcohols 7AI has been proposed to undergo ESDPT following the latter scenario 9–11. Although 7AI/water complexes formed in aprotic solvents have been suggested to undergo ESDPT as well,13a the intrinsic proton‐transfer dynamics of Nb has been rarely studied experimentally and is not well understood 12…”

Section: Methodsmentioning

confidence: 99%

Asymmetric Double Proton Transfer of Excited 1:1 7‐Azaindole/Alcohol Complexes with Anomalously Large and Temperature‐Independent Kinetic Isotope Effects

et al. 2004

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“…The process occurs on the time scale of single picoseconds and is not stopped by lowering of temperature or by increasing the viscosity of the medium. On the contrary, the reaction is slower and viscosity-dependent in 7AI complexes [21], since it requires a solvent rearrangement around an excited chromophore [22][23][24][25][26][27]. These different phototautomerization characteristics reflect different intermolecular HB strengths, imposed by molecular structure.…”

Section: Introductionmentioning

confidence: 99%

Polymorphism, Hydrogen Bond Properties, and Vibrational Structure of 1H-Pyrrolo[3,2-h]Quinoline Dimers

Gorski

Gawinkowski

Luboradzki

et al. 2012

Journal of Atomic, Molecular, and Optical Physics

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Two forms of cyclic, doubly hydrogen-bonded dimers are discovered for crystalline 1H-pyrrolo[3,2-h]quinoline, a bifunctional molecule possessing both hydrogen bond donor and acceptor groups. One of the forms is planar, the other is twisted. Analysis of IR and Raman spectra, combined with DFT calculations, allows one to assign the observed vibrations and to single out vibrational transitions which can serve as markers of hydrogen bond formation and dimer structure. Raman spectra measured for samples submitted to high pressure indicate a transition from the planar towards the twisted structure. Formation of intermolecular hydrogen bonds leads to a large increase of the Raman intensity of the NH stretching band: it can be readily observed for the dimer, but is absent in the monomer spectrum.

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“…58,59,[62][63][64]69 Phototautomerization has also been discovered in complexes of 7AI with alcohols and water. [70][71][72][73][74][75][76][77][78][79][80][81][82][83][84] We have been carrying out detailed studies of bifunctional chromophores based on indole, pyrrole, pyridine, and carbazole units, such as 2-(2′-pyridyl)indoles, 4,5,8,13,18,20,21,31 2-(2′-pyridyl)-pyrrole, 32,85 7-(pyridyl)indoles, 35 dipyrido[2,3-a:3′,2′-i]carbazole, 10,22,25 7,8,9,10-tetrahydro-11H-pyrido [2,3-a]carbazole, 18,22 or 1H-pyrrolo [3,2-h]quinoline. 19,21,22,27,31,86 These molecules, structurally similar to 7AI, differ in the number of bonds between the proton donor (the NH group) and the acceptor (pyridine...…”

Section: Introductionmentioning

confidence: 99%

Structure and Photophysics of 2-(2‘-Pyridyl)benzindoles: The Role of Intermolecular Hydrogen Bonds

et al. 2007

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The photophysical properties of two isomeric 2-(2′-pyridyl)benzindoles depend on the environment. Strong fluorescence is detected in nonpolar and polar aprotic solvents. In the presence of alcohols, the emission reveals an unusual behavior. Upon titration of n-hexane solutions with ethanol, the fluorescence intensity goes through a minimum and then increases with rising alcohol concentration. Transient absorption and timeresolved emission studies combined with ground-and excited-state geometry optimizations lead to the conclusion that two rotameric forms, syn and anti, coexist in alcohols, whereas in nonpolar and aprotic polar media, only the syn conformation is present. The latter can form cyclic complexes with alcohols, which are rapidly depopulated in the excited state. In the presence of excess alcohol, syn f anti rotamerization occurs in the ground state, promoted by the cooperative action of nonspecific and specific effects such as solvent polarity increase and the formation of hydrogen bonds to both donor and acceptor sites of the bifunctional compounds.

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Solute–solvent interaction in the photoinduced tautomerization of 7-azaindole in various alcohols and in mixtures of cyclohexane and ethanol

Cited by 76 publications

References 4 publications

Asymmetric Double Proton Transfer of Excited 1:1 7‐Azaindole/Alcohol Complexes with Anomalously Large and Temperature‐Independent Kinetic Isotope Effects

Asymmetric Double Proton Transfer of Excited 1:1 7‐Azaindole/Alcohol Complexes with Anomalously Large and Temperature‐Independent Kinetic Isotope Effects

Polymorphism, Hydrogen Bond Properties, and Vibrational Structure of 1H-Pyrrolo[3,2-h]Quinoline Dimers

Structure and Photophysics of 2-(2‘-Pyridyl)benzindoles: The Role of Intermolecular Hydrogen Bonds

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