Intramolecular Hydrogen-bonded Systems Research Articles

Hydrogen bonding and tautomerism studied by isotope effects on chemical shifts

Deuterium isotope effects on 13C chemical shifts are investigated in intramolecular hydrogen-bonded systems. As models, o-hydroxydibenzoylmethane and tetracycline (TC) are chosen. The OH proton is exchanged and the deuterium isotope effects at carbons, nΔC(OD), are studied in both localised and tautomeric situations. Factors influencing the isotope effects are the nature of donors, acceptors, the intervening double bonds and local substituents. The isotope effects of the D ring of TC are shown to be similar to isotope effects in o-hydroxyacetophenone. The central β-diketone system in both compounds is shown to be tautomeric and strongly shifted towards a form with a keto group forming a hydrogen bond to the phenolic hydroxy group of ring A. This double hydrogen bond to one acceptor weakens both hydrogen bonds. Interesting long-range effects are emerging from this situation. The A ring of TC is shown to contain a CC(OH)NH2 moiety.

1H and 13C NMR studies of intramolecular hydrogen bonds in substitued 2,6-bis(diethylaminomethyl)phenol di-N-oxides and their monotetrahcloroaurates

Abstract Ten substituted 2,6-bis(diethylaminomethyl)phenol di- N -oxides (2,6-DNO) and their monotetrachloroaurates were studied by 1 H and 13 C NMR spectroscopy. With the 2,6-DNO, the chemical shift of the hydrogen-bonded proton demonstrates that equilibria occur betwen the non-polar and polar structures of the intramolecular hydrogen bond (OH ⋯ OH ⇌ O − ⋯ H + ON) and between a homoconjugated intramolecular hydrogen bond (NO ⋯ H + ⋯ ON). With the monotetrahcloroaurates of the 2,6-DNO, an intramolecular hydrogen-bonded system is formed in which a collective proton motion proceeds and which shows large proton polarizability. The 1 H NMR chemical shifts of the hydrogen-bonded protons become first stronger and after a maximum again weaker. The 13 C NMR results prove that this method is a useful tool for studies of molecular hydrogen bonds in which collective proton motion occurs.

Conformational study of alanine and α‐aminoisobutyric Ψ[NHCO]‐retroamide peptide analogues

The minimum-energy conformations of N,N'-dimethyl-2-methylmalondiamide (2mMA) and N,N'-dimethyl-2-dimethylmalondiamide (2dmMA) have been computed using the AM1 method. The results show that molecules tend to form an intramolecular six-membered ring hydrogen-bond system. The same trend is observed in crystals of malonamide derivatives substituted in the central carbon atom. The results are also compared with previous molecular-mechanics calculations. The conformational trends of 2mMA and 2dmMA are very similar to those showed by N,N'-dimethylmalondiamide. Details of the computed conformational energy maps for 2mMA and 2dmMA compounds are given.

Pulse radiolytic one-electron reduction of 2-hydroxy- and 2,6-dihydroxy-9,10-anthraquinones

The semiquinone free radicals produced by one-electron reduction of 2-hydroxy-9,10-anthraquinone (2HAQ) and 2,6-dihydroxy-9,10-anthraquinone (26DHAQ) in aqueous formate solution, water–isopropyl alcohol–acetone mixed solvent and isopropyl alcohol have been studied using the pulse radiolysis technique. The absorption characteristics, kinetic parameters of formation and decay, acid–base behaviour and redox characteristics of the semiquinones have been investigated and compared with the corresponding characteristics of a few intramolecularly hydrogen-bonded anthrasemiquinone derivatives. The non-hydrogen-bonded semiquinones show two pKa values (4.7 and 10.7 for 2HAQ and 5.4 and 8.7 for 26DHAQ, respectively) within the pH range 1–14, whereas other intramolecularly hydrogen-bonded semiquinones show only one pKa. The one-electron reduction potential (E′7) values for 2HAQ (–440 mV) and 26DHAQ (–400 mV) are more negative than those of the intramolecularly hydrogen-bonded systems.

Correction. Toward the Photostability Mechanism of Intramolecular Hydrogen Bond Systems. The Photophysics of 1'-Hydroxy-2'-acetonaphthone

Correction. Toward the Photostability Mechanism of Intramolecular Hydrogen Bond Systems. The Photophysics of 1'-Hydroxy-2'-acetonaphthone

Toward the photostability mechanism of intramolecular hydrogen bond systems. The photophysics of 1'-hydroxy-2'-acetonaphthone

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTToward the photostability mechanism of intramolecular hydrogen bond systems. The photophysics of 1'-hydroxy-2'-acetonaphthoneJavier Catalan and Juan Carlos del ValleCite this: J. Am. Chem. Soc. 1993, 115, 10, 4321–4325Publication Date (Print):May 1, 1993Publication History Published online1 May 2002Published inissue 1 May 1993https://doi.org/10.1021/ja00063a057RIGHTS & PERMISSIONSArticle Views322Altmetric-Citations99LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (509 KB) Get e-Alerts Get e-Alerts

Gaussian density functional calculations on hydrogen-bonded systems

As a test of the applicability of the density functional theory to systems containing hydrogen bonds, linear combination of Gaussian type orbitals-local density calculations have been performed on two intermolecular and two intramolecular hydrogen-bonded systems. A comparison is made of results using the local density approximation (LDA) and those including nonlocal density gradient type corrections, using two different nonlocal functionals. The calculated minimum energy structures for the water dimer and the formamid-water complex are presented

Vibrational circular dichroism in hydrogen bond systems: Part III. Vibrational circular dichroism of the OH stretching vibrations of 1,2-diols and β-methoxyalcohols

Vibrational circular dichroism (VCD) of the OH stretching vibrations in intramolecular hydrogen bond systems, i.e. 1,2-diols and β-methoxyalcohols, has been studied. The VCD feature of the OH stretching mode is discussed in relation to the molecular conformation, with the aid of the results of 1H NMR spectroscopy. The positive VCD observed for the OH stretching vibration of the donor hydroxyl group in intramolecular hydrogen bond systems is attributable to the G− conformation about the OCCO bond. The rotational strengths calculated on the basis of the dynamic polarization model account for the observed VCD feature.

Proton polarizability due to collective proton motion in intramolecular hydrogen-bonded systems in monoperchlorates of 2,6-bis[(diethylamino)methyl]-4-R-phenol di-N-oxides as a function of the pKa of the phenolic group

Proton polarizability due to collective proton motion in intramolecular hydrogen-bonded systems in monoperchlorates of 2,6-bis[(diethylamino)methyl]-4-R-phenol di-N-oxides as a function of the pKa of the phenolic group

The influence of temperature on the proton polarizability of an intramolecular hydrogen-bonded system within the gossypol molecule

The gossypol molecule was studied in CH 2Cl 2 solution as a function of temperature using FTIR spectroscopy. With decreasing temperature some molecules associate via phenol-phenol hydrogen bonds. Furthermore, with decreasing temperature the hydrogen-bonded system O 6H...O 7H...OC⇌O 6 −...HO 7...HOC + gains a large proton polarizability caused by collective proton motion within this system.

Vibrational circular dichroism in hydrogen bond systems: Part II. Vibrational circular dichroism of the OH stretching vibration in 2,2-dimethyl-1,3-dioxolane-4-methanol

Vibrational circular dichroism (VCD) of the OH stretching band in 2,2-dimethyl-1,3- dioxolane-4-methanol has been studied. The OH stretching vibration for the intramolecularly hydrogen-bonded species in the (R)-enantiomer gives rise to a positive VCD band but no VCD band for the hydrogen-bond free species. It is shown that the G −G + conformation in the intramolecular hydrogen bond system ▪ gives a positive VCD band for the OH stretching vibration. The thermodynamic parameters in equilibrium between the free and intramolecularly hydrogen-bonded species have been determined as Δ H =−7.8 kJ mol −1 and Δ S = −18 kJ K −1 mol −1.

Angle-resolved photoelectron spectroscopy of intramolecular hydrogen bond systems: 2-chloroethanol and 2-bromoethanol

He(I) photoelectron angular distributions of typical intramolecular hydrogen bond systems, 2-chloroethanol and 2-bromoethanol, were measured. The intramolecular hydrogen bonds were found not to influence the photoelectron angular distributions for the halogen atom lone pair bands of these compounds. This result is useful for spectral band assignments.

ChemInform Abstract: STUDIES IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY. 17. DEUTERON QUADRUPOLE COUPLING CONSTANTS IN INTRAMOLECULARLY HYDROGEN BONDED SYSTEMS

Chemischer InformationsdienstVolume 11, Issue 29 Physical Organic Chemistry ChemInform Abstract: STUDIES IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY. 17. DEUTERON QUADRUPOLE COUPLING CONSTANTS IN INTRAMOLECULARLY HYDROGEN BONDED SYSTEMS L. M. JACKMAN, L. M. JACKMANSearch for more papers by this authorJ. C. TREWELLA, J. C. TREWELLASearch for more papers by this authorR. C. HADDON, R. C. HADDONSearch for more papers by this author L. M. JACKMAN, L. M. JACKMANSearch for more papers by this authorJ. C. TREWELLA, J. C. TREWELLASearch for more papers by this authorR. C. HADDON, R. C. HADDONSearch for more papers by this author First published: July 22, 1980 https://doi.org/10.1002/chin.198029051AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume11, Issue29July 22, 1980 RelatedInformation

ChemInform Abstract: CRYSTAL STRUCTURE OF 9‐HYDROXYPHENALENONE: A VERY SHORT INTRAMOLECULAR HYDROGEN BOND SYSTEM

Chemischer InformationsdienstVolume 11, Issue 1 Physical Organic Chemistry ChemInform Abstract: CRYSTAL STRUCTURE OF 9-HYDROXYPHENALENONE: A VERY SHORT INTRAMOLECULAR HYDROGEN BOND SYSTEM C. SVENSSON, C. SVENSSONSearch for more papers by this authorS. C. ABRAHAMS, S. C. ABRAHAMSSearch for more papers by this authorJ. L. BERNSTEIN, J. L. BERNSTEINSearch for more papers by this authorR. C. HADDON, R. C. HADDONSearch for more papers by this author C. SVENSSON, C. SVENSSONSearch for more papers by this authorS. C. ABRAHAMS, S. C. ABRAHAMSSearch for more papers by this authorJ. L. BERNSTEIN, J. L. BERNSTEINSearch for more papers by this authorR. C. HADDON, R. C. HADDONSearch for more papers by this author First published: January 8, 1980 https://doi.org/10.1002/chin.198001089AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume11, Issue1January 8, 1980 RelatedInformation

Crystal structure of 9-hydroxyphenalenone: a very short intramolecular hydrogen bond system

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTCrystal structure of 9-hydroxyphenalenone: a very short intramolecular hydrogen bond systemC. Svensson, S. C. Abrahams, J. L. Bernstein, and R. C. HaddonCite this: J. Am. Chem. Soc. 1979, 101, 19, 5759–5764Publication Date (Print):September 1, 1979Publication History Published online1 May 2002Published inissue 1 September 1979https://doi.org/10.1021/ja00513a048RIGHTS & PERMISSIONSArticle Views180Altmetric-Citations28LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (603 KB) Get e-AlertsSupporting Info (1)»Supporting Information Supporting Information Get e-Alerts

ChemInform Abstract: APPLICATION OF PHOTOELECTRON SPECTROSCOPY TO INTRAMOLECULARLY HYDROGEN‐BONDED SYSTEMS. PART III. THE PHOTOELECTRON SPECTRA OF CIS AND TRANS 2‐SUBSTITUTED CYCLOPENTANOLS AND CIS AND TRANS 2‐SUBSTITUTED CYCLOHEXANOLS

Chemischer InformationsdienstVolume 7, Issue 43 Physical Organic Chemistry ChemInform Abstract: APPLICATION OF PHOTOELECTRON SPECTROSCOPY TO INTRAMOLECULARLY HYDROGEN-BONDED SYSTEMS. PART III. THE PHOTOELECTRON SPECTRA OF CIS AND TRANS 2-SUBSTITUTED CYCLOPENTANOLS AND CIS AND TRANS 2-SUBSTITUTED CYCLOHEXANOLS R. S. BROWN, R. S. BROWNSearch for more papers by this author R. S. BROWN, R. S. BROWNSearch for more papers by this author First published: October 26, 1976 https://doi.org/10.1002/chin.197643031AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume7, Issue43October 26, 1976 RelatedInformation

The O–D out-of-plane deformation of enolized β-dicarbonyl compounds

The O–D out-of-plane deformation of enolized β-dicarbonyls is a useful indication of the strength of intramolecular hydrogen-bond systems.