title: A novel crown ether generation containing different heteroaromatic cations: synthesis, characterization, solid-phase (13)C NMR, X-ray crystal structure, and selective amino acid recognition.
abstract: The synthesis and structural characterization of a novel generation of crown ethers, 3, 5 and 6 containing pyrilium, thiopyrilium, and pyridinium subunits, respectively, are reported. The crown ether unit is potentially capable of forming host-guest complexes with inorganic and organic cations, while the heteroaromatic cationic unit is suitable to bind with anions. A variety of physicochemical methods including electrospray mass spectrometry, UV-vis spectroscopy, solution and solid-phase NMR, and X-ray crystallography were applied for structural characterization of the new crown ether derivatives. The (1)H and (13)C NMR studies indicate rapid rotation of the B9C3 unit about the C-C bond that connects the two units to each other. Single crystals for 3, 4, and 5 were successfully obtained, and their X-ray crystal structures were resolved. The perchlorate anion in 3 (orthorhombic, space group P2(1)2(1)2(1)) and 5 (orthorhombic, space group P2(1)) is far from O(+) and close to S(+). The solid-phase structure of 3 and 5 show small deviation from planarity for the four aromatic rings, whereas two of the aromatic rings in 4 are out of heteroaromatic ring. Spectrophotometric studies in methanol solution revealed that the ligand 3 can be successfully applied to selective amino acid recognition.
authors.affiliation: Department of Chemistry, University of Imam Hossein, Tehran, Iran. samoghimi@yahoo.com
authors.forename: Abolghasem
authors.initials: A
authors.lastname: Moghimi
authors.forename: Majid Faal
authors.initials: MF
authors.lastname: Rastegar
authors.forename: Mehdi
authors.initials: M
authors.lastname: Ghandi
authors.forename: Masoud
authors.initials: M
authors.lastname: Taghizadeh
authors.forename: Abdollah
authors.initials: A
authors.lastname: Yari
authors.forename: Mojtaba
authors.initials: M
authors.lastname: Shamsipur
authors.forename: Glenn P A
authors.initials: GP
authors.lastname: Yap
authors.forename: Hamid
authors.initials: H
authors.lastname: Rahbarnoohi
mesh_terms: D000465:Algorithms; D000596:Amino Acids / Q000737:chemistry*; D001665:Binding Sites; D002412:Cations / Q000737:chemistry; D002625:Chemistry, Organic / Q000379:methods; D018360:Crystallography, X-Ray; D004988:Ethers, Cyclic / Q000138:chemical synthesis* / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008968:Molecular Conformation; D015394:Molecular Structure; D021241:Spectrometry, Mass, Electrospray Ionization; D013056:Spectrophotometry, Ultraviolet
chemical_list: D000596:Amino Acids; D002412:Cations; D004988:Ethers, Cyclic