+ Site Statistics
+ Search Articles
+ Subscribe to Site Feeds
Most Shared
PDF Full Text
+ PDF Full Text
Request PDF Full Text
+ Follow Us
Follow on Facebook
Follow on Twitter
Follow on LinkedIn
+ Translate
+ Recently Requested

Proton transfer in the intramolecular NHN+ bonds in proton sponges with different hydrogen bridge flexibility

Proton transfer in the intramolecular NHN+ bonds in proton sponges with different hydrogen bridge flexibility

Physical Chemistry Chemical Physics 11(9): 1297-1302

The proton transfer in the intramolecular NHN(+) hydrogen bonds of selected proton sponges has been studied using theoretical calculations of the potential energy surfaces (PES). The proton-transfer trajectory follows very closely the lowest energy path, derived as the quantum-mechanical reaction coordinates (QMRC). The bond order is not conserved in the transfer process. Even in the most flexible proton sponges there are considerable constraints on the NN distance and the hydrogen bonds do not behave as intermolecular bonds. The curvature of QMRC is not a suitable criterion to distinguish between inter- and intramolecular NHN(+) bonds. It appears that the determining factor for linearity is the degree of constraint, which is most likely the strongest in the benzene proton sponges. In the naphthalene proton sponges with relatively short NN distances QMRC is more bent than in the benzene complexes with somewhat longer distances, opposite to what might be expected. It is important to note that in intramolecular complexes the PES is characterized by a single minimum, in contrast to a double minimum in intermolecular complexes. The experimentally determined NH bond lengths have been plotted on the potential energy surface and these points are all located on the QMRC curve, very close to the energy minimum of the PES. However, it is vital that the experimental X-ray hydrogen positions are then corrected to give the true internuclear NH distances.

(PDF emailed within 0-6 h: $19.90)

Accession: 055260601

Download citation: RISBibTeXText

PMID: 19224029

DOI: 10.1039/b814798a

Related references

NHN+ intramolecular hydrogen bonds: heat of formation and parameters of some proton sponges. Journal of Molecular Structure 525(1-3): 247-251, 2000

Protonation of naphthalene proton sponges containing higher N-alkyl groups Structural consequences on proton accepting properties and intramolecular hydrogen bonding. Journal of Molecular Structure 892(1-3): 63-67, 2008

Spin-spin coupling across intramolecular N-H(+)-N hydrogen bonds in models for proton sponges: an ab initio investigation. Magnetic Resonance in Chemistry 46(5): 457-463, 2008

The influence of steric effects of proton-transfer equilibrium in intramolecular hydrogen bonds. Journal of Molecular Structure 221: 109-114, 1990

Proton transfer equilibrium in the intramolecular hydrogen bridge in sterically hindered Schiff bases. Journal of Molecular Structure 615(1-3): 97-108, 2002

Glutamic acid hydrogen phosphate hydrogen bonds proton polarizability and proton transfer as a function of the cations present and of the degree of hydration ir investigations. Journal of the Chemical Society Faraday Transactions I 84(4): 885-898, 1988

Proton-bridge motions in amine conjugate acid ions having intramolecular hydrogen bonds to hydroxyl and amine groups. Journal of Physical Chemistry. A 117(6): 1360-1369, 2013

Proton transfer in and proton polarizability of hydrogen bonds: IR and theoretical studies regarding mechanisms in biological systems. Journal of Molecular Structure 177: 43-68, 1988

Proton polarizability and proton transfer in histidine-phosphate hydrogen bonds as a function of cations present: ir investigations. Biopolymers 26(1): 95-108, 1987

Car-Parrinello and Path Integral Molecular Dynamics Study of the Proton Transfer in the Intramolecular Hydrogen Bonds in the Ketohydrazone-Azoenol System. Journal of Physical Chemistry. B: -, 2018

Thermodynamics of proton transfer in carboxylic acid retinal schiff bass hydrogen bonds with large proton polarizability. Biochemical & Biophysical Research Communications 138(2): 819-825, 1986

Dependence of Calculated NMR Proton Chemical Shifts on Electron Density Properties in Proton-Transfer Processes on Short Strong Hydrogen Bonds. Journal of Physical Chemistry A 108(52): 11783-11792, 2004

Proton dynamics in an extended array of hydrogen bonds: normal coordinates, proton transfer and macroscopic quantum entanglement in the ground state. Journal of Molecular Structure 700(1-3): 133-145, 2004

Proton transfer triggered proton transfer: a self-assisted twin excited state intramolecular proton transfer. Physical Chemistry Chemical Physics, 2018

Excited state intramolecular proton transfer (ESIPT) in six-coordinated zinc(ii)-quinoxaline complexes with ligand hydrogen bonds: their fluorescent properties sensitive to axial positions. Dalton Transactions 39(8): 1989-1995, 2010