title: NMR analysis of a series of 1,2-bis(1-R-5-oxo-2,3-dihydro-1H-pyrrol-4-ylidene)ethanes and X-ray crystal structure analysis of the R = mesityl compound.
abstract: Four tetramethyl 4,4'-(ethane-1,2-diylidene)bis[1-R-5-oxo-4,5-dihydro-1H-pyrrole-2,3-dicarboxylate] compounds, denoted class (1), are a series of conjugated buta-1,3-dienes substituted with a heterocyclic group. The compounds can be used as dyes and pigments due to their long-range conjugated systems. Four structures were studied using (1)H NMR, (13)C NMR and mass spectroscopy, viz. with R = 2,4,6-trimethylphenyl, (1a), R = cyclohexyl, (1b), R = tert-butyl, (1c), and R = isopropyl, (1d). A detailed discussion is presented regarding the characteristics of the three-dimensional structures based on NMR analysis and the X-ray crystal structure of (1a), namely tetramethyl 4,4'-(ethane-1,2-diylidene)bis[5-oxo-1-(2,4,6-trimethylphenyl)-4,5-dihydro-1H-pyrrole-2,3-dicarboxylate], C36H36N2O10. The conjugation plane and stability were also studied via quantum chemical calculations.
authors.affiliation: College of Life Science and Bio-engineering, Beijing University of Technology, Pingleyuan Street No. 100, Chaoyang District, Beijing, People's Republic of China.
authors.forename: Qi
authors.initials: Q
authors.lastname: Liu
authors.affiliation: College of Life Science and Bio-engineering, Beijing University of Technology, Pingleyuan Street No. 100, Chaoyang District, Beijing, People's Republic of China.
authors.forename: Xiu-Qing
authors.initials: XQ
authors.lastname: Song
authors.affiliation: College of Life Science and Bio-engineering, Beijing University of Technology, Pingleyuan Street No. 100, Chaoyang District, Beijing, People's Republic of China.
authors.forename: Hong
authors.initials: H
authors.lastname: Yan
mesh_terms: D001555:Benzene Derivatives / Q000737:chemistry*; D002264:Carboxylic Acids / Q000737:chemistry*; D004396:Coloring Agents / Q000737:chemistry*; D018360:Crystallography, X-Ray; D006571:Heterocyclic Compounds / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D011758:Pyrroles / Q000737:chemistry*; D011789:Quantum Theory
chemical_list: D001555:Benzene Derivatives; D002264:Carboxylic Acids; D004396:Coloring Agents; D006571:Heterocyclic Compounds; D011758:Pyrroles; C000596210:tetramethyl 4,4'-(ethane-1,2-diylidene)bis(1-R-5-oxo-4,5-dihydro-1H-pyrrole-2,3-dicarboxylate); C010219:mesitylene
keywords: NMR analysis; NOESY analysis; buta-1,3-dienes; conjugation; crystal structure; dyes; pigments; quantum chemical calculations; tetracarboxylates