Pyridyl Units Research Articles

Self-Assembly of Liquid-Crystalline Polyamide Complexes through the Formation of Double Hydrogen Bonds between a 2,6-Bis(amino)pyridine Moiety and Benzoic Acids

Supramolecular liquid-crystalline polymeric complexes derived from polyamides containing 2,6-bis(amino)pyridyl units in their main chains and benzoic acid derivatives have been obtained by the formation of intermolecular double hydrogen bonds. The polymeric complexes behave as single liquid-crystalline polymers and exhibit stable and enantiotropic mesophases. The hydrogen-bonded mesogens laterally connected by flexible spacers form a polymeric structure that is not simply classified as a main-chain or a side-chain type.

Crowned polyacetylene: 3. Synthesis and cation-binding property of polyphenylacetylene with azacrown cavity by cyclopolymerization of α,ω-bis(4′-ethynylphenoxy)oligooxyethylene containing a pyridyl unit

The cyclopolymerizations of 2,6-bis[7′-(4″-ethynylphenoxy)-2′,5′-dioxaheptyl]pyridine ( 1a) and 2,6-bis[10′-(4″-ethynylphenoxy)-2′,5′,8′-trioxadecyl]pyridine ( 1b) were carried out using the (bicyclo[2.2.1]hepta-2,5-diene)rhodium(I) chloride dimer. The yellowish powdery, organic solvent-soluble polymers were obtained using an amine as a cocatalyst. The resulting polymers consisted of cyclic constitutional repeating units as the main structure along with pendant acetylenic groups, i.e. the extent of cyclization was from 0.89 to 0.99 for the polyphenylacetylenes with an azacrown cavity, 2a and 2b, obtained from monomers 1a and 1b, respectively. Polymer 2 exhibited cation-binding ability for alkaline earth metal, heavy metal, and transition metal ions and, in particular, for Ag +. The complex of 2 with Ag +, which was confirmed by the 1H n.m.r. spectrum, consisted of the azacrown cavity and Ag + with a ratio of 2.

Cover Picture (Angew. Chem. Int. Ed. Engl. 10/1995)

Angewandte Chemie International Edition in EnglishVolume 34, Issue 10 Cover PictureFree Access Cover Picture (Angew. Chem. Int. Ed. Engl. 10/1995) First published: June 2, 1995 https://doi.org/10.1002/anie.199510431Citations: 12AboutPDF 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 Graphical Abstract The cover picture shows the arrangement of two 1:1 complexes composed of a cyclic zinc porphyrin tetramer (Zn4−1) and a central meso-tetra-4-pyridyl-porphyrin unit (H2-Py4P) in the solid state (view along the c axis; purple = N, blue = C, yellow = Zn). The central porphyrin ligand, which is coordinated to each zinc center in Zn4−1 through an N atom of a pyridyl unit, locks the five-porphyrin assembly in a single conformation. NMR spectra indicate that the complex H2-Py4P·Zn4−1 prefers to adopt a tub-shaped geometry reminiscent of cyclooctatetraene. The picture was produced with the program Insight II from Biosym Technologies of San Diego using a Silicon Graphics Workstation. We would like to thank Dr. Robert Thomas and Prof. Dr. François Diederich (ETH Zürich Switzerland) for their help in producing this picture. Further details of the structure and fluorescence properties of this multicomponent system are reported by S. Anderson et al. on pp. 1096ff. Citing Literature Volume34, Issue10June 2, 1995 RelatedInformation

A Liquid‐Crystalline Polymer Network Built by Molecular Self‐Assembly through Intermolecular Hydrogen Bonding

Liquid-Crystalline behavior over a wide temperature range and reversible phase transitions are observed for the polymer network 1, which is held together by hydrogen bonds between benzoic acid and pyridyl units

Interaction of environmentally important metal ions with nitrogen–sulfur-donor macrocycles. The crystal structures of seven-co-ordinate lead(II) and mercury(II) complexes of an 18-membered N4S2macrocycle

Metal-ion-templated cyclocondensations of two acyclic diamines containing nitrogen and sulfur heteroatoms with pyridine-2,6-dicarbaldehyde in the presence of the ions PbII, HgII, CdII and AgI afforded 1 : 1 complexes of the appropriate metal ion with the corresponding 18-membered, potentially sexidentate (N4S2), diimine macrocycle L1 or L2. The soluble lead, mercury and cadmium complexes show strong metal–imine interactions in the NMR spectra: they are rare examples of co-ordination compounds of these ions that exhibit satellites due to proton and carbon-13 coupling to the naturally abundant metal nuclei with spin I=½. The crystal structures of the complexes [PbL1(MeOH)(H2O)][ClO4]21a and [HgL1(SCN)2]·MeOH 2 have been determined. In both complexes the macrocycle adopts a stepped conformation with respect to the two pyridyl units; this conformation facilitates endo-dentate configurations for the sulfur donors which interact through long bonds to the metal which, in turn, is located towards the trimethine part of the macrocycle. The combination of the asymmetrical location of the metal ion within the macrocyclic cavity and the long bonds to the sulfurs leaves the second pyridine nitrogen remote and unco-ordinated. The metal geometry in 1a is best described as a very distorted nido-hexagonal bipyramid in which the macrocycle donors occupy five of the six ‘quatorial’ sites and solvent molecules define severely bent ‘axial’ positions, implicating a stereochemically active role for the 6s2 lone-pair electrons on PbII. The structure of 2 is similar to that of 1a but the axial positions are linear and occupied by thiocyanate ions; in contrast to 1a, the mercury atom is displaced well out of the plane of the trimethine co-ordinating fragment. Both are rare examples of structural characterisations of the interaction of mixed nitrogen–sulfur-donor macrocycles with these toxic heavy-metal ions.

Synthesis, spectroscopy, and crystal structure of a new stable biscyclopentadienyl uranium(IV) dichloride containing two C 5H 4-rings interlinked by a metal-coordinated 2,6-bis(methylene)pyridyl unit

Reaction of the new disodium salt: Na 2[2,6-C 5H 3N(CH 2C 5H 4) 2 ( 2; 2,6-C 5H 3N = 2,6-pyridyl) with UCl 4 in THF affords the reddish-green, mononuclear Cp 2U IVCl 2-derivative (Cp  η 5-C 5H 5): μ-{2,6-CH 2C 5H 3NCH 2}(η 5-C 5H 4) 2U IVCl 2 ( 1. According to a single-crystal X-ray study, 1 involves a notably strong UN bond (UN av: 2.62(1) Å) along with two nonequivalent Cl ligands (UCl: 2.615(3) and 2.636(3) Å). The low-temperature 1H NMR spectrum of the paramagnetic complex is in full accord with the solid state structure 1. Up to room temperature, the dissolved molecules of 1 show no fluxionality on the NMR time scale, although the two CH 2 proton resonances appear to undergo coalescence.

ChemInform Abstract: Synthesis of a New Macrocyclic Polyether Containing Pyridyl and Diethylene Glycol Units.

ChemInformVolume 20, Issue 43 Heterocyclic Compounds ChemInform Abstract: Synthesis of a New Macrocyclic Polyether Containing Pyridyl and Diethylene Glycol Units. J. J. TRIVEDI, J. J. TRIVEDI Cent. Salt&Mar. Chem. Res. Inst., Bhavnagar 364 002Search for more papers by this authorV. K. INDUSEKHAR, V. K. INDUSEKHAR Cent. Salt&Mar. Chem. Res. Inst., Bhavnagar 364 002Search for more papers by this author J. J. TRIVEDI, J. J. TRIVEDI Cent. Salt&Mar. Chem. Res. Inst., Bhavnagar 364 002Search for more papers by this authorV. K. INDUSEKHAR, V. K. INDUSEKHAR Cent. Salt&Mar. Chem. Res. Inst., Bhavnagar 364 002Search for more papers by this author First published: October 24, 1989 https://doi.org/10.1002/chin.198943195AboutPDF 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. Volume20, Issue43October 24, 1989 RelatedInformation

Chiral crowns incorporating pyridyl units and tertiary amine functions

The chiral hosts DD-(1) and DD-(7) have been synthesised and the temperature dependence of the 1H n.m.r. spectrum of the 1:1 complex between DD-(1) and benzylammonium thiocyanate in solution has been interpreted in terms of slow dissociation of the complex.

Synthesis of the indolo[2′,3′:3,4]pyrido[1,2-b][2,7]naphthyridinone alkaloid nauclefine and its ring-Eisomers

Nauclefine has been reported to be the only product from the photocyclisation of the enamide derived from harmalan and nicotinoyl chloride. Re-investigation has shown, however, that two compounds are formed: the alkaloid and an isomer in which cyclisation to the 2-position of the pyridyl unit has occurred. These components have been separated and the remaining ring-E isomers have been synthesized. 1H and 13C n.m.r. data for these structures are analysed.

Effects of structural changes on chiral selectivity in molecular complexation

Seven macrocyclic ethers containing 2,2′-substituted-1,1′-binaphthyl units as chiral barriers connected through different combinations of OCH2CH2OCH2-CH2O, O[CH2]5O, m-C6H4(CH2O)2 and 2,6-C5H3N(CH2O)2(substituted pyridyl) units complex differently with the enantiomers of the hexafluorophosphate salts of racemic methyl phenylglycinate and methyl valinate.

Pyridyl unit in host compounds

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPyridyl unit in host compoundsMartin Newcomb, George W. Gokel, and Donald J. CramCite this: J. Am. Chem. Soc. 1974, 96, 21, 6810–6811Publication Date (Print):October 1, 1974Publication History Published online1 May 2002Published inissue 1 October 1974https://doi.org/10.1021/ja00828a071RIGHTS & PERMISSIONSArticle Views605Altmetric-Citations54LEARN 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 (245 KB) Get e-Alerts Get e-Alerts