U V photoelectron spectroscopy and C N D O j S molecular orbital calculations have been employed to investigate the electronic structure of cytosine ( I ) , 1-methylcytosine (II), N,1-dimethylcytosine ( I I I ) , N,N,l-trimethylcytosine (IV), 3-methylcytosine (V) , 1,5-dimethylcytosine (VI ) , 1,6-dimethylcytosine (VI I ) , 5-methylcytosine ( V I I I ) , and 6-methylcytosine (IX). The resolution of the spectra obtained for different members of this series of molecules varies markedly. Of all the molecules investigated the photoelectron bands arising from the five uppermost orbitals are well resolved only for N , I-dimethylcytosine. The variation in the resolution arises partially from the overlapping of bands. Furthermore, spectra obtained for molecules in which labile H atoms are replaced by methyl groups exhibit much better resolution than spectra for other molecules. This observation is probably related to hydrogen bonding effects. For cytosine the spacing of bands occurring in the spectrum is accurately reproduced in the results of C N D O / S calculations carried out on the 1(H) aminooxo tautomeric form of the molecule. In compounds 11-IV and VI-IX the spacing of bands and the shifts observed in the spectra are also well predicted by calculations carried out on the aminooxo tautomers. However, for 3-methylcytosine the results indicate that an imino tautomeric form is most stable. For all compounds the C N D O / S calculations indicate that three of the five uppermost orbitals are A orbitals and that two are lone-pair orbitals. In cytosine the first and fifth bands arise from A orbitals while the fourth band arises from a lone-pair orbital. The second and third bands arise from a A and a lone-pair orbital which are strongly overlapping and their ordering remains uncertain. Introduction electron distributions associated with the valence orbitals of these molecules influence the manner in which purines and pyrimidines participate in weak bonding interactions as well as in chemical reaction^.^-^ The valence structure of biological purines and pyrimidines The valence molecular orbital structure of biological purines and pyrimidines plays an important role in determining the biochemical properties of these molecules.' Energies and 0002-7863/78/ 1500-2303$01 .OO/O

Proton NMR spectroscopy was used to investigate the partial orientation of the aromatic counterions anilinium and benzenephosphonate in an amphiphilic nematic liquid crystal. The inclusion of the anilinium ion in a sodium decylsulphate phase sample can induce a change in the sign of the diamagnetic anisotropy from negative to positive. Under similar conditions the inclusion of the benzenephosphonate ion in a tetradecyltrimethylammonium bromide phase sample did not produce a change in the sign of the diamagnetic anisotropy. These differences are explained in terms of the greater solubility of benzenephosphonate in the aqueous region which is born out by the degree of orientation measurements

Proton N.M.R. is used to investigate the inclusion of the phenylsulphonate and the benzoate ion as counterions in samples of amphiphilic nematic liquid crystals. When these aromatic counterions are substituted in sufficient amounts the sign of the diamagnetic anisotropy is reversed. The orientation parameters are also shown to be dependent upon the micelle shape, as well as the sign of the diamagnetic anisotropy.

The 1H N.M.R. of the methyl phosphonate ion has been used as a probe in the investigation of the reversal of the diamagnetic anisotropy in amphiphilic nematic liquid crystals. Three classes of aromatic counterion substitution have been investigated involving sodium and ceasium decylsulphate and the aromatic counterions trimethylanalinium and analinium. It was found that, in the absence of diamagnetic anisotropy considerations, in the trimethylanalinium/ceasium decylsulphate system the signs of the 1H N.M.R. dipolar couplings of the methyl phosphonate ion were reversed. This is explained in terms of ion binding and various degrees of protonation of the methyl phosphonate species.

Caesium N.M.R. spectra of the caesium ion have been measured in a nematic lyotropic liquid-crystalline solution prepared from caesium decylsulphate/decanol/water. The contributions of an asymmetry parameter, a second order quadrupole coupling and a hexadecapole coupling to the spectra have been discussed. The N.M.R. spectra was shown to be consistent with the occurrence of a hexadecapole interaction in the quadrupole split spectrum. The ratio = 1:0.0000034 was obtained.

The 13C NMR spectra of 21 catechin derivatives substituted at C‐6/C‐8 by bromine and/or hydrogen and at oxygen by methyl, acetyl and/or hydrogen have been analysed in deuteriated acetone and chloroform. When a methoxy group is flanked by two bulky ortho substituents (6‐Br and C‐4), the MeO and ortho/para ring carbons (C‐4a, C‐6, C‐8) are deshielded owing to steric inhibition of resonance, which permits a distinction between 6‐ and 8‐substituted catechin methyl ethers. Hindered acetoxy groups do not give rise to this phenomenon.

The condensation of vanadate (VO4H21−) with a variety of substituted phenols in aqueous acetone solution has been studied by 51V nuclear magnetic resonance spectroscopy. The formation constants for the various product esters were determined, as were their respective pKa values. Inductive and resonance contributions to vanadate ester formation were investigated using the dual substituent parameter approach. This procedure did not succeed particularly well, although trends were clearly observed. Correlations with Hammett constants were compared with those of the dual parameter approach. The observation of some linear free-energy relationships was interpreted to mean that the inductive and resonance parameters generally ascribed to the various phenols are not directly applicable to vanadate ester formation where d orbitals are probably involved. The results did indicate that resonance effects have a significantly greater influence on ester formation than do inductive effects.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTBinding interactions of tetrahedral ions in aqueous surfactant solutionKeith Radley and Alan S. TraceyCite this: J. Phys. Chem. 1985, 89, 12, 2657–2661Publication Date (Print):June 1, 1985Publication History Published online1 May 2002Published inissue 1 June 1985https://pubs.acs.org/doi/10.1021/j100258a045https://doi.org/10.1021/j100258a045research-articleACS PublicationsRequest reuse permissionsArticle Views29Altmetric-Citations5LEARN 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 InRedditEmail Other access options Get e-Alerts

AbstractThe chemicals cis (Z) and trans (E)11-tetradecenyl acetate (11–14:Ac), trans 11-tetradecen-1-ol (E11–14:OH) and trans 11-tetradecenal (E11–14:Ald) were isolated from unmated female Choristoneura orae Freeman and shown to be highly attractive when used as lures in sticky traps. The identification of these components of the sex pheromone facilitates the separation of C. orae from other Pinaceae-feeding Choristoneura in the same area.

AbstractDie Wechselwirkung des Kations von AlCl3°C H2O mit den carbonylierten Leitgruppen von K‐ dodecanoat, das in einer Zweischichtenmembran enthalten ist, wurde NMR‐spektroskopisch untersucht.

Novel aqueous type II lyotropic mesophases that align in magnetic fields have been synthesized for binary and ternary mixtures of amphiphiles. A system in which major components of the micelle bilayer are decyltrimethylammonium and dodecanoate ions is an aligning mesophase from 100% to 35% dodecanoate, but replacement of the cationic amphiphile with hexadecyltrimethylammonium facilitates the extension to aligning mesophases up to 100% replacement of the dodecanoate ions. A study of sodium and deuterium quadrupole splittings observed in their nuclear magnetic resonance spectra, confirms and extends a three site adsorption theory for sodium ion in the mixed head group interface. The first site is associated with more strongly hydrated ions and head groups and involves adjacent dodecanoate head groups, the second is not so strongly hydrated and involves one dodecanoate group while the third is a weakly bound water at - N(CH3)+ groups and a sodium remote from the interface layer in close to average isotropic motion. Mixed detergent mesophases of type II, which spontaneously align in the field, have also been synthesized from variable mixtures of hexadecyltrimethylammonium bromide and decylammonium chloride and from mixtures of potassium dodecanoate and sodium decylsulphate. In the mixed cationic system the sodium quadrupole splittings are always low but water is tightly bound to the -NH3 + head group. In the anionic detergent mixture sodium appears about as strongly bound to dodecanoate and decylsulphate head groups. In most of the mixed mesophases some decanol is required (maximum 25% of the bilayer) in order to render the desired type II mesophase stable over a range of mixtures of the charged detergents. Specific site adsorption for sodium and water, peculiar to different head groups renders the effect of the added decanol as primarily a convenient diluent in the bilayer to preserve mesophase integrity.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTEffect of counterion substitution on the type and nature of nematic lyotropic phases from nuclear magnetic resonance studiesK. Radley, L. W. Reeves, and A. S. TraceyCite this: J. Phys. Chem. 1976, 80, 2, 174–182Publication Date (Print):January 1, 1976Publication History Published online1 May 2002Published inissue 1 January 1976https://pubs.acs.org/doi/10.1021/j100543a018https://doi.org/10.1021/j100543a018research-articleACS PublicationsRequest reuse permissionsArticle Views206Altmetric-Citations131LEARN 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 InRedditEmail Other access options Get e-Alerts

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTNuclear magnetic resonance studies of the di-, tri-, and tetramethylammonium ions oriented in middle nematic soap phasesL. W. Reeves and A. S. TraceyCite this: J. Am. Chem. Soc. 1974, 96, 23, 7176–7180Publication Date (Print):November 1, 1974Publication History Published online1 May 2002Published inissue 1 November 1974https://pubs.acs.org/doi/10.1021/ja00830a002https://doi.org/10.1021/ja00830a002research-articleACS PublicationsRequest reuse permissionsArticle Views64Altmetric-Citations9LEARN 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 InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts

Chemischer InformationsdienstVolume 6, Issue 50 Physical Organic Chemistry ChemInform Abstract: STUDIES OF MEMBRANE PROCESSES PART 7, HYDROCARBON CHAIN MOTIONS AND THE EFFECT OF CHANGING COUNTERIONS L. W. REEVES, L. W. REEVESSearch for more papers by this authorA. S. TRACEY, A. S. TRACEYSearch for more papers by this author L. W. REEVES, L. W. REEVESSearch for more papers by this authorA. S. TRACEY, A. S. TRACEYSearch for more papers by this author First published: December 16, 1975 https://doi.org/10.1002/chin.197550075AboutPDF 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. Volume6, Issue50December 16, 1975 RelatedInformation