title: New fluorous ponytailed 4-[(2,2,2-trifluoroethoxy)methyl]pyridinium halide salts.
abstract: It is possible that fluorous compounds could be utilized as directing forces in crystal engineering for applications in materials chemistry or catalysis. Although numerous fluorous compounds have been used for various applications, their structures in the solid state remains a lively matter for debate. The reaction of 4-[(2,2,2-trifluoroethoxy)methyl]pyridine with HX (X = I or Cl) yielded new fluorous ponytailed pyridinium halide salts, namely 4-[(2,2,2-trifluoroethoxy)methyl]pyridinium iodide, C8H9F3NO+·I-, (1), and 4-[(2,2,2-trifluoroethoxy)methyl]pyridinium chloride, C8H9F3NO+·Cl-, (2), which were characterized by IR spectroscopy, multinuclei (1H,13C and19F) NMR spectroscopy and single-crystal X-ray diffraction. Structure analysis showed that there are two types of hydrogen bonds, namely N-H...X and C-H...X. The iodide anion in salt (1) is hydrogen bonded to three 4-[(2,2,2-trifluoroethoxy)methyl]pyridinium cations in the crystal packing, while the chloride ion in salt (2) is involved in six hydrogen bonds to five 4-[(2,2,2-trifluoroethoxy)methyl]pyridinium cations, which is attributed to the smaller size and reduced polarizability of the chloride ion compared to the iodide ion. In the IR spectra, the pyridinium N-H stretching band for salt (1) exhibited a blue shift compared with that of salt (2).
authors.affiliation: Institute of Organic and Polymeric Materials, National Taipei University of Technology, Taipei 106, Taiwan.
authors.forename: Norman
authors.initials: N
authors.lastname: Lu
authors.affiliation: Institute of Organic and Polymeric Materials, National Taipei University of Technology, Taipei 106, Taiwan.
authors.forename: Mani
authors.initials: M
authors.lastname: Alagesan
authors.affiliation: Institute of Organic and Polymeric Materials, National Taipei University of Technology, Taipei 106, Taiwan.
authors.forename: Chi Liang
authors.initials: CL
authors.lastname: Ho
authors.affiliation: Institute of Organic and Polymeric Materials, National Taipei University of Technology, Taipei 106, Taiwan.
authors.forename: Rong Jyun
authors.initials: RJ
authors.lastname: Wei
authors.affiliation: Institute of Organic and Polymeric Materials, National Taipei University of Technology, Taipei 106, Taiwan.
authors.forename: Chih Chieh
authors.initials: CC
authors.lastname: Kung
authors.affiliation: Graduate Institute of Medical Sciences, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan.
authors.forename: Jung Shan
authors.initials: JS
authors.lastname: Chang
authors.affiliation: Institute of Chemistry, Academia Sinica, Taipei 115, Taiwan.
authors.forename: Yuh Sheng
authors.initials: YS
authors.lastname: Wen
authors.affiliation: Institute of Organic and Polymeric Materials, National Taipei University of Technology, Taipei 106, Taiwan.
authors.forename: Ling Kang
authors.initials: LK
authors.lastname: Liu
keywords: IR spectroscopy; bifurcated hydrogen bonding; blue shift; crystal structure; fluorous ponytailed pyridine; hydrogen halides; synthon