Conformational equilibria and photoinduced tautomerization in 2-(2′-pyridyl)pyrrole

Kijak, Michał; Zielińska, Anna; Chamchoumis, Charles; Herbich, Jerzy; Thummel, Randolph P.; Waluk, Jacek

doi:10.1016/j.cplett.2004.10.121

Cited by 32 publications

(58 citation statements)

References 20 publications

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“…Very similar energy differences between the syn and anti forms have been calculated previously for 3 32 and 4 20 . The dipole moment in the ground state of the anti form is larger than that of the syn form; for 1, µ(syn) ) 2.…”

Section: Calculationssupporting

confidence: 66%

“…Indeed, we observed that for 2-(2′-pyridyl)pyrrole (PP), traces of the anti form could be observed in acetonitrile, 32 whereas for the larger 2-(2′-pyridyl)indole (PyIn-0), this form could only be detected in alcohols. 20 In order to find out whether a further increase in molecular size can reduce the effect of nonspecific solvation, this work examined two isomeric molecules closely related to PP and PyIn-0.…”

Section: Introductionmentioning

confidence: 96%

“…It has been demonstrated for 3 32 and 4 20 that the anti form is dominant in bulk alcohols because two strong, linear hydrogen bonds with two different alcohol molecules, possible for this form, are energetically more favorable than the hydrogen bond arrangement in the complexed syn species.…”

Section: D) and 4 (24 And 34 D)mentioning

confidence: 99%

“…5,26 Finally, for molecules with separate moieties containing proton donor and acceptor groups linked by a single bond, such as 2-(2′-pyridyl)-indole and 2-(2′-pyridyl)pyrrole, we observed alcohol-induced syn-anti rotamerization in the ground state. 20,32 The syn structures, with both nitrogen atoms on the same side of the molecule, are more stable in nonpolar and polar aprotic solvents, whereas in alcohols, the energy ordering is reversed, and the anti forms become dominant. Two factors are responsible for the syn-anti equilibrium shift.…”

Section: Introductionmentioning

confidence: 99%

“…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%

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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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Section: Calculationssupporting

confidence: 66%

Section: Introductionmentioning

confidence: 96%

Section: D) and 4 (24 And 34 D)mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

et al. 2007

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Studies of Photoinduced NH Tautomerism by Stationary and Time‐Resolved Fluorescence Techniques

2013

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Three Modes of Proton Transfer in One Chromophore: Photoinduced Tautomerization in 2‐(1H‐Pyrazol‐5‐yl)Pyridines, Their Dimers and Alcohol Complexes

et al. 2012

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Studies of 2-(1H-pyrazol-5-yl)pyridine (PPP) and its derivatives 2-(4-methyl-1H-pyrazol-5-yl)pyridine (MPP) and 2-(3-bromo-1H-pyrazol-5-yl)pyridine (BPP) by stationary and time-resolved UV/Vis spectroscopic methods, and quantum chemical computations show that this class of compounds provides a rare example of molecules that exhibit three types of photoreactions: 1) excited-state intramolecular proton transfer (ESIPT) in the syn form of MPP, 2) excited-state intermolecular double-proton transfer (ESDPT) in the dimers of PPP in nonpolar media, as well as 3) solvent-assisted double-proton transfer in hydrogen-bonded 1:1 complexes of PPP and MPP with alcoholic partners. The excited-state processes are manifested by the appearance of a dual luminescence and a bimodal irreversible kinetic coupling of the two fluorescence bands. Ground-state syn-anti equilibria are detected and discussed. The fraction of the higher-energy anti form varies for different derivatives and is strongly dependent on the solvent polarity and hydrogen-bond donor or acceptor abilities.

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Conformational equilibria and photoinduced tautomerization in 2-(2′-pyridyl)pyrrole

Cited by 32 publications

References 20 publications

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

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

Studies of Photoinduced NH Tautomerism by Stationary and Time‐Resolved Fluorescence Techniques

Three Modes of Proton Transfer in One Chromophore: Photoinduced Tautomerization in 2‐(1H‐Pyrazol‐5‐yl)Pyridines, Their Dimers and Alcohol Complexes

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