Hydrogen bond formation between 4-(dimethylamino)pyridine and aliphatic alcohols

A. Demeter, Viktória Mile, T. Bérces

Research output: Contribution to journalArticle

14 Citations (Scopus)

Abstract

The photophysics of 4-(dimethylamino)pyridine (DMAP) has been investigated in different solvents in the presence of aliphatic and fluorinated aliphatic alcohols, respectively. For most systems, consecutive two-step hydrogen-bonded complex formation is observed in the presence of alcohols. Equilibrium constants are determined from UV spectroscopic results for the formation of singly and doubly complexed species. The resolved absorption and fluorescence spectra for the singly and doubly complexed DMAP are derived by means of the equilibrium constants. Exceptionally large hydrogen bond basicity values are found for the ground and singlet excited DMAP molecules. In n-hexane, as a consequence of complex formation, the intramolecular charge transfer (ICT) emission becomes dominant over of the locally excited fluorescence; the fluorescence and triplet yields increase considerably with complexation. In polar solvents, both the fluorescence and triplet yields of the complex are much smaller than that of the uncomplexed DMAP. The dipole moments derived for the singly complexed species from the Lippert-Mataga analysis are much larger than those of the uncomplexed molecules. However, for the relaxed ICT excited-state one obtains different dipole moments in apolar and polar solvents. This may be explained by a conformational change of the molecule in the ICT excited state from planar geometry in apolar solvent to the perpendicular structure (characterized with bigger dipole moment) in polar solvent.

Original languageEnglish
Pages (from-to)8942-8949
Number of pages8
JournalJournal of Physical Chemistry A
Volume111
Issue number37
DOIs
Publication statusPublished - Sep 20 2007

Fingerprint

pyridines
Hydrogen bonds
alcohols
Alcohols
hydrogen bonds
Dipole moment
Fluorescence
Charge transfer
fluorescence
dipole moments
charge transfer
Equilibrium constants
Excited states
Molecules
molecules
Alkalinity
Complexation
excitation
Hydrogen
pyridine

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

Cite this

Hydrogen bond formation between 4-(dimethylamino)pyridine and aliphatic alcohols. / Demeter, A.; Mile, Viktória; Bérces, T.

In: Journal of Physical Chemistry A, Vol. 111, No. 37, 20.09.2007, p. 8942-8949.

Research output: Contribution to journalArticle

@article{8983fc167df94206abfa1ffe31a0956a,
title = "Hydrogen bond formation between 4-(dimethylamino)pyridine and aliphatic alcohols",
abstract = "The photophysics of 4-(dimethylamino)pyridine (DMAP) has been investigated in different solvents in the presence of aliphatic and fluorinated aliphatic alcohols, respectively. For most systems, consecutive two-step hydrogen-bonded complex formation is observed in the presence of alcohols. Equilibrium constants are determined from UV spectroscopic results for the formation of singly and doubly complexed species. The resolved absorption and fluorescence spectra for the singly and doubly complexed DMAP are derived by means of the equilibrium constants. Exceptionally large hydrogen bond basicity values are found for the ground and singlet excited DMAP molecules. In n-hexane, as a consequence of complex formation, the intramolecular charge transfer (ICT) emission becomes dominant over of the locally excited fluorescence; the fluorescence and triplet yields increase considerably with complexation. In polar solvents, both the fluorescence and triplet yields of the complex are much smaller than that of the uncomplexed DMAP. The dipole moments derived for the singly complexed species from the Lippert-Mataga analysis are much larger than those of the uncomplexed molecules. However, for the relaxed ICT excited-state one obtains different dipole moments in apolar and polar solvents. This may be explained by a conformational change of the molecule in the ICT excited state from planar geometry in apolar solvent to the perpendicular structure (characterized with bigger dipole moment) in polar solvent.",
author = "A. Demeter and Vikt{\'o}ria Mile and T. B{\'e}rces",
year = "2007",
month = "9",
day = "20",
doi = "10.1021/jp072989i",
language = "English",
volume = "111",
pages = "8942--8949",
journal = "Journal of Physical Chemistry A",
issn = "1089-5639",
publisher = "American Chemical Society",
number = "37",

}

TY - JOUR

T1 - Hydrogen bond formation between 4-(dimethylamino)pyridine and aliphatic alcohols

AU - Demeter, A.

AU - Mile, Viktória

AU - Bérces, T.

PY - 2007/9/20

Y1 - 2007/9/20

N2 - The photophysics of 4-(dimethylamino)pyridine (DMAP) has been investigated in different solvents in the presence of aliphatic and fluorinated aliphatic alcohols, respectively. For most systems, consecutive two-step hydrogen-bonded complex formation is observed in the presence of alcohols. Equilibrium constants are determined from UV spectroscopic results for the formation of singly and doubly complexed species. The resolved absorption and fluorescence spectra for the singly and doubly complexed DMAP are derived by means of the equilibrium constants. Exceptionally large hydrogen bond basicity values are found for the ground and singlet excited DMAP molecules. In n-hexane, as a consequence of complex formation, the intramolecular charge transfer (ICT) emission becomes dominant over of the locally excited fluorescence; the fluorescence and triplet yields increase considerably with complexation. In polar solvents, both the fluorescence and triplet yields of the complex are much smaller than that of the uncomplexed DMAP. The dipole moments derived for the singly complexed species from the Lippert-Mataga analysis are much larger than those of the uncomplexed molecules. However, for the relaxed ICT excited-state one obtains different dipole moments in apolar and polar solvents. This may be explained by a conformational change of the molecule in the ICT excited state from planar geometry in apolar solvent to the perpendicular structure (characterized with bigger dipole moment) in polar solvent.

AB - The photophysics of 4-(dimethylamino)pyridine (DMAP) has been investigated in different solvents in the presence of aliphatic and fluorinated aliphatic alcohols, respectively. For most systems, consecutive two-step hydrogen-bonded complex formation is observed in the presence of alcohols. Equilibrium constants are determined from UV spectroscopic results for the formation of singly and doubly complexed species. The resolved absorption and fluorescence spectra for the singly and doubly complexed DMAP are derived by means of the equilibrium constants. Exceptionally large hydrogen bond basicity values are found for the ground and singlet excited DMAP molecules. In n-hexane, as a consequence of complex formation, the intramolecular charge transfer (ICT) emission becomes dominant over of the locally excited fluorescence; the fluorescence and triplet yields increase considerably with complexation. In polar solvents, both the fluorescence and triplet yields of the complex are much smaller than that of the uncomplexed DMAP. The dipole moments derived for the singly complexed species from the Lippert-Mataga analysis are much larger than those of the uncomplexed molecules. However, for the relaxed ICT excited-state one obtains different dipole moments in apolar and polar solvents. This may be explained by a conformational change of the molecule in the ICT excited state from planar geometry in apolar solvent to the perpendicular structure (characterized with bigger dipole moment) in polar solvent.

UR - http://www.scopus.com/inward/record.url?scp=34948907409&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=34948907409&partnerID=8YFLogxK

U2 - 10.1021/jp072989i

DO - 10.1021/jp072989i

M3 - Article

C2 - 17718545

AN - SCOPUS:34948907409

VL - 111

SP - 8942

EP - 8949

JO - Journal of Physical Chemistry A

JF - Journal of Physical Chemistry A

SN - 1089-5639

IS - 37

ER -