1-Methyl-2-((1E,3E)-4-phenylbuta-1,3-dienyl)pyridinium iodide: Synthesis, characterization, and X-ray analysis

Article abstract of DOI:10.1134/S0022476614040180

1-Methyl-2-((1E,3E)-4-phenylbuta-1,3-dienyl)pyridinium iodide (1) is synthesized and characterized by UV-Vis, FT-IR, ¹H and ¹³C NMR, and single crystal X-ray diffraction. Compound 1 crystallizes in an orthorhombic Iba2 space group with the unit cell parameters a = 12.8236(11) ?, b = 20.1216(17) ?, c = 11.2071(10) ?, V = 2891.8(4) ?³ and Z = 8. X-ray diffraction indicates that the molecule of 1 displays E,E configurations with respect to the two middle C=C double bonds. The molecular structure of 1 is twisted and the dihedral angle between the pyridinium and phenyl rings is 15.0(2)°. In the crystal packing, cations form stacks in an anti-parallel V-shaped manner along the a axis through π-π interactions between pyridinium and phenyl rings.

Full text of DOI:10.1134/S0022476614040180

Journal of Structural Chemistry. Vol. 55, No. 4, pp. 713-716, 2014.
Original Russian Text © 2014 S. Chantrapromma, N. Boonnak, N. Kaewmanee, P. Ruanwas, H.-K. Fun.
1-METHYL-2-((1E,3E)-4-PHENYLBUTA-1,3-
DIENYL)PYRIDINIUM IODIDE:
SYNTHESIS, CHARACTERIZATION, AND X-RAY ANALYSIS
1 2
S. Chantrapromma, N. Boonnak, N. Kaewmanee,
1
UDC 541.6:547.12
1
P. Ruanwas, and H.-K. Fun
3,4
1-Methyl-2-((1E,3E)-4-phenylbuta-1,3-dienyl)pyridinium iodide (1) is synthesized and characterized by
1 13
UV-Vis, FT-IR, H and C NMR, and single crystal X-ray diffraction. Compound 1 crystallizes in an
orthorhombic Iba2 space group with the unit cell parameters a = 12.8236(11) Å, b = 20.1216(17) Å,
3
c = 11.2071(10) Å, V = 2891.8(4) Å and Z = 8. X-ray diffraction indicates that the molecule of 1 displays
E,E configurations with respect to the two middle C=C double bonds. The molecular structure of 1 is
twisted and the dihedral angle between the pyridinium and phenyl rings is 15.0(2)°. In the crystal packing,
cations form stacks in an anti-parallel V-shaped manner along the a axis through π–π interactions between
pyridinium and phenyl rings.
DOI: 10.1134/S0022476614040180
Keywords: crystal structure, pyridinium, quaternary ammonium compound (QAC), π stacking, π–π
interaction.
INTRODUCTION
Quaternary ammonium compounds (QACs) are generally known to be bioactive substances and are used mainly for
environmental disinfection, disinfection of medical equipments, and disinfection in hospitals. However, due to the long-term
usage of common QACs such as benzalkonium chloride and cetylpyridinium chloride, QACs resistant microorganisms have
appeared. It was reported that some Staphylococcus spp. contain genes conveying resistance to this type of disinfectant [1-3].
Therefore, we have developed novel QACs which can overcome this Staphylococcus-resistant phenomenon by exhibiting
strong anti-methicillin-resistant Staphylococcus aureus activity and reported this discovery in our previous work [4]. From
this significant reason, title compound (1) was designed by extending the π-conjugated length as compared to the compounds
in our previous work [4], and synthesized for a better antibacterial activity. Single crystal X-ray diffraction of 1 was
performed in order to study the molecular structure and determine the interactions in the formation of the crystal.
1
Department of Chemistry, Faculty of Science, Prince of Songkla University, Hat-Yai, Songkhla, Thailand;
2
suchada.c@psu.ac.th. Faculty of Traditional Thai Medicine, Prince of Songkla University, Hat-Yai, Songkhla, Thailand.
3
4
Department of Pharmaceutical Chemistry, College of Pharmacy, King Saud University, Riyadh, Saudi Arabia. X-ray
Crystallography Unit, School of Physics, Universiti Sains Malaysia, Penang, Malaysia. The text was submitted by the authors
in English. Zhurnal Strukturnoi Khimii, Vol. 55, No. 4, pp. 747-750, July-August, 2014. Original article submitted
January 28, 2013.
0022-4766/14/5504-0713 © 2014 by Pleiades Publishing, Ltd.
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EXPERIMENTAL
Synthesis of 1-methyl-2-((1E,3E)-4-phenylbuta-1,3-dienyl)pyridinium iodide (1). Compound 1 was prepared by
mixing 1:1:1 solutions of 1,2-dimethylpyridinium iodide (2 g, 8.5 mmol), cinnamaldehyde (1.1 g, 8.5 mmol), and piperidine
(0.84 ml, 8.5 mmol) in methanol (40 ml). The resulting solution was refluxed for 2 h in the nitrogen atmosphere. The yellow
solid which formed was filtered, washed with diethyl ether, dried in vacuo and purified by recrystallization from methanol by
slow evaporation at room temperature to yield yellow block-shaped single crystals suitable for the X-ray diffraction analysis
over a few weeks; melting point 245-247°C (decompose).
(1)
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UV-Vis, FT-IR, H NMR and C-NMR characterization. UV-Vis (CH3OH) λmax (nm): 260.3, 375.7; IR (KBr,
–1
cm ): ν(CH stretching) 2995 (m), ν(C=C alkene stretching) 1590 (s), ν(C=C aromatic stretching) 1565 (s), ν(C-N stretching)
1
1251; H NMR (300 MHz, DMSO-d6): δ (ppm) 8.86 (d, J = 6.3 Hz, 1H, H-6), 8.45 (d, J = 4.2 Hz, Hz, 2H, H-3 & H-4), 7.85
(dt, J = 6.3, 4.2 Hz, 1H, H-5), 7.80 (dd, J = 15.0, 10.5 Hz, 1H, H-2′), 7.63 (dd, J = 8.4, 1.2 Hz, 2H, H-2″ & H-6″), 7.44 (br t,
J = 8.4 Hz, 2H, H-3″ & H-5″), 7.39 (dd, J = 15.0, 11.1 Hz, 1H, H-3′), 7.39 (td, J = 8.4, 1.5 Hz, 1H, H-4″), 7.19 (d,
13
J = 15.0 Hz, 1H, H-1′), 7.17 (d, J = 15.0 Hz, 1H, H-4′), 4.28 (s, 3H, CH3-1); C NMR (75 MHz, DMSO-d6): δ (ppm) 152.5
(C-2), 146.4 (C-6), 144.5 (C-4), 143.9 (C-2′), 141.3 (C-4′), 136.3 (C-1″), 129.9 (C-3′), 129.5 (C-3″ & C-5″), 128.4 (C-4″),
127.8 (C-2″ & C-6″), 125.2 (C-5), 124.9 (C-3), 121.1 (C-1′), 46.3 (CH3-1).
Materials and measurements. All the chemicals and solvents were of analytical grade, purchase commercially, and
◦
used as received. Melting point was recorded in C and measured using an electrothermal melting point apparatus. Infrared
spectra were recorded using a FTS 165 FT-IR spectrophotometer. Ultraviolet-visible (UV-Vis) absorption spectra were
1 13
recorded using a Shimadzu UV-2450 UV-Visible spectrophotometer. H and C NMR spectra were recorded on a 300 MHz
TM
Bruker FT-NMR Ultra Shield spectrometer in a DMSO-d6 solvent with TMS as the internal standard. Chemical shifts are
reported in δ(ppm) and coupling constants (J ) are expressed in Hertz.
X-ray diffraction study. A yellow single crystal of 1 of the dimensions 0.19×0.17×0.12 mm was selected and data
collection was performed on a Bruker Apex2 CCD diffractometer with graphite monochromated MoK (λ = 0.71073 Å)
α
radiation at a detector distance of 5 cm using APEX2 [5] at 100.0(1) K with the Oxford Cryosystem Cobra low-temperature
attachment. The collected data were reduced using the SAINT program [5], and the empirical absorption corrections were
performed using the SADABS program [5]. The structures were solved by direct methods and refined by least-squares using
the SHELXTL software package [6]. All non-hydrogen atoms were refined anisotropically. H atoms were placed in
calculated positions with C–H = 0.95 Å for aromatic and CH, 0.98 Å for CH3. The Uiso(H) values were constrained to be
1.5Ueq of the carrier atom for methyl H atoms and 1.2Ueq for the remaining H atoms. A rotating group model was used for the
methyl group. The final refinement converged well. The crystal is racemic twinning. The BASF was refined to 0.226(1).
Materials for publication were prepared using SHELXTL [6], PLATON [7], and Mercury [8]. The molecular formula of 1 is
C16H16NI, the formula weight is Mr = 349.20, the crystal system is orthorhombic, the space group is Iba2 with the unit cell
3 3
parameters a = 12.8236(11) Å, b = 20.1216(17) Å, c = 11.2071(10) Å, V = 2891.8(4) Å , Z = 8 and Dcalc = 1.604 g/cm . Out
of 3223 independent reflections, 2833 I > 2σ(I ) were used in the refinement. The final least-square cycle of the refinement by
2
full-matrix least squares methods on F gave R1 = 0.0325, wR2 = 0.0598 and GOOF = 1.071.
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Fig. 1. Molecular structure of 1 showing the atom labeling scheme.
Fig. 2. View of the unit cell packing of 1 along the c
axis, showing the stacking of the cations. H atoms were
omitted for clarity.
RESULTS AND DISCUSSION
Single crystal X-ray analysis. Single crystal X-ray diffraction analysis reveals that compound 1 crystallizes in
+ –
orthorhombic Iba2 and consists of a C18H16N cation and an I anion. The molecular structure and the atom labeling scheme
of 1 is shown in Fig. 1.
The cation molecule exists in the E,E configurations with respect to the C6=C7 and C8=C9 double bonds. The bond
lengths of 1.337(7) Å and 1.350(6) Å for C6=C7 and C8=C9 respectively is consistent with the double bond character. The
C1–C6–C7–C8 and C7–C8–C9–C10 torsion angles are 174.7(5)° and 173.0(5)° indicate the trans configurations. The cation
molecule is twisted with the dihedral angle between the pyridinium (C1–C5/N1) and the phenyl (C10–C15) rings being
15.0(2)°, which may result from the long π-conjugated bridge (C6–C9) and the C–C (C1–C6 and C9–C10) single bond
rotation between the central bridge and pyridinium and phenyl rings. The middle buta-1,3-dienyl unit (C6–C9) is almost
planar with the torsion angle C6–C7–C8–C9 = –178.7(5)°. The mean plane through this middle bridge makes the dihedral
angles of 7.2(5)° and 7.9(5)° with the pyridinium and phenyl rings respectively. The methyl substituent is almost coplanar
with the pyridinium ring with the C16–N1–C1–C5 torsion angle of 176.5(4)°. The cation bond lengths are in normal ranges
[9] and are comparable with the closely related structure [10].
In the crystal packing (Fig. 2), the cations are stacked in an anti-parallel V-shaped manner along the a axis with
ii
significant π–π interactions between the pyridinium and phenyl rings, with the centroid-centroid distance of Cg1…Cg2
=
3.711(3) Å; Cg1 and Cg2 are the centroids of the C1–C5/N1 and C10–C15 rings respectively; symmetry code: (ii) 1/2–x,
1/2–y, 1/2+z]. The iodide ions are located interstitially amongst the cations. The compound is stabilized and consolidated by
Coulomb interactions between the ions and π–π interactions.
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CONCLUSIONS
In this study, 1-methyl-2-((1E,3E)-4-phenylbuta-1,3-dienyl)pyridinium iodide (1) was successfully synthesized and
1
13
characterized by UV-Vis, FT-IR, H and C NMR, and single crystal X-ray diffraction. The X-ray diffraction study reveals
that the molecule of 1 exists in the E,E configurations with respect to the two middle C=C double bonds and the molecule is
slightly bent. In the solid state, the crystal structure is stabilized and consolidated by Coulomb interactions between the ions
and π–π interactions.
CIF file containing complete information on the studied structure was deposited with the Cambridge
Crystallographic Data Center, CCDC No. 917917, and is freely available upon request from the following website:
www.ccdc.cam.ac.uk/data_request/cif or by contacting the Cambridge Crystallographic Data Centre, 12, Union Road,
Cambridge CB2 1EZ, UK; fax: +44 1223 336033; email: deposit@ccdc.cam.ac.uk.
The authors thank Prince of Songkla University for financial support. The authors extend their appreciation to the
Deanship of Scientific Research at the King Saud University for funding the work through the research group project
No. RGP-VPP-207.
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