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Article: α,ω-diaminoalkanes as models for bases that dicoordinate the proton: An evaluation of the kinetic method for estimating their proton affinities

Titleα,ω-diaminoalkanes as models for bases that dicoordinate the proton: An evaluation of the kinetic method for estimating their proton affinities
Authors
Issue Date1999
PublisherAmerican Chemical Society. The Journal's web site is located at http://pubs.acs.org/jpca
Citation
Journal Of Physical Chemistry A, 1999, v. 103 n. 43, p. 8700-8705 How to Cite?
AbstractThe effectiveness of the kinetic method for estimating the proton affinities of bases that di-coordinate the proton is evaluated using α,ω-diaminoalkanes as model bases. The proton affinities of these diamines have previously been examined using the equilibrium method and critically evaluated. Calculations using density functional theory at the B3LYP/6-31++G(d,p) level confirm that protonated α,ω-diaminoalkanes have cyclic structures with the proton covalently bound to one of the amino nitrogen atoms and hydrogen-bonded to the other. Furthermore, this cyclic structure persists in the protonated heterodimer ion between an α,ω-diaminoalkane and ammonia (the model reference base); binding of the two bases takes place via a second hydrogen bond between the RNH 3 + and ammonia. Measuring the proton affinities under several collision energies and extrapolating to zero collision energy yields proton affinities that are smaller than the reference values by -2.8 kcal/mol, on average. Application of the Fenselau correction gives proton affinities that differ from the reference values by ±1.0 kcal/mol. These results indicate that the kinetic method is effective for estimating the proton affinities of molecules that tend to have more than one potential protonation site. Application of this method is particularly suited to biological molecules, such as peptides, where application of the equilibrium method is impossible due to low sample volatility.
Persistent Identifierhttp://hdl.handle.net/10722/167274
ISSN
2015 Impact Factor: 2.883
2015 SCImago Journal Rankings: 1.231
ISI Accession Number ID
References

 

DC FieldValueLanguage
dc.contributor.authorWang, Zen_US
dc.contributor.authorChu, IKen_US
dc.contributor.authorRodriquez, CFen_US
dc.contributor.authorHopkinson, ACen_US
dc.contributor.authorSiu, KWMen_US
dc.date.accessioned2012-10-08T03:05:07Z-
dc.date.available2012-10-08T03:05:07Z-
dc.date.issued1999en_US
dc.identifier.citationJournal Of Physical Chemistry A, 1999, v. 103 n. 43, p. 8700-8705en_US
dc.identifier.issn1089-5639en_US
dc.identifier.urihttp://hdl.handle.net/10722/167274-
dc.description.abstractThe effectiveness of the kinetic method for estimating the proton affinities of bases that di-coordinate the proton is evaluated using α,ω-diaminoalkanes as model bases. The proton affinities of these diamines have previously been examined using the equilibrium method and critically evaluated. Calculations using density functional theory at the B3LYP/6-31++G(d,p) level confirm that protonated α,ω-diaminoalkanes have cyclic structures with the proton covalently bound to one of the amino nitrogen atoms and hydrogen-bonded to the other. Furthermore, this cyclic structure persists in the protonated heterodimer ion between an α,ω-diaminoalkane and ammonia (the model reference base); binding of the two bases takes place via a second hydrogen bond between the RNH 3 + and ammonia. Measuring the proton affinities under several collision energies and extrapolating to zero collision energy yields proton affinities that are smaller than the reference values by -2.8 kcal/mol, on average. Application of the Fenselau correction gives proton affinities that differ from the reference values by ±1.0 kcal/mol. These results indicate that the kinetic method is effective for estimating the proton affinities of molecules that tend to have more than one potential protonation site. Application of this method is particularly suited to biological molecules, such as peptides, where application of the equilibrium method is impossible due to low sample volatility.en_US
dc.languageengen_US
dc.publisherAmerican Chemical Society. The Journal's web site is located at http://pubs.acs.org/jpcaen_US
dc.relation.ispartofJournal of Physical Chemistry Aen_US
dc.titleα,ω-diaminoalkanes as models for bases that dicoordinate the proton: An evaluation of the kinetic method for estimating their proton affinitiesen_US
dc.typeArticleen_US
dc.identifier.emailChu, IK:ivankchu@hku.hken_US
dc.identifier.authorityChu, IK=rp00683en_US
dc.description.naturelink_to_subscribed_fulltexten_US
dc.identifier.doi10.1021/jp9914976-
dc.identifier.scopuseid_2-s2.0-0000454306en_US
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-0000454306&selection=ref&src=s&origin=recordpageen_US
dc.identifier.volume103en_US
dc.identifier.issue43en_US
dc.identifier.spage8700en_US
dc.identifier.epage8705en_US
dc.identifier.isiWOS:000083538100018-
dc.publisher.placeUnited Statesen_US
dc.identifier.scopusauthoridWang, Z=7410042322en_US
dc.identifier.scopusauthoridChu, IK=7103327484en_US
dc.identifier.scopusauthoridRodriquez, CF=7004085075en_US
dc.identifier.scopusauthoridHopkinson, AC=15067169300en_US
dc.identifier.scopusauthoridSiu, KWM=35312218500en_US

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