Effect of counter ions on the mesogenic ionic: N -phenylpyridiniums

Article abstract of DOI:10.1039/c8ce00286j

Two series of ionic liquid crystals (ILCs) derived from N-phenylpyridinium 1-2 were prepared and their mesomorphic properties were investigated. A versatile and effective method was developed to prepare these ionic compounds 2-X from their precursor chloride 2-Cl. X-ray crystal structure analyses of three single crystals revealed that a sandwiched head-to-head or bilayer lamellar structure induced by H-bonds in the solid state was observed. The anion was proximally intercalated near the head group. Weak H-bonds were induced and attributed to the formation of mesophases. The type of counter anions has a significant influence on the stability of the mesophase, ΔT_SmA = 221.3 (2-Cl) > 213.1 (2-SCN) > 173.9 (2-BF₄) > 85.4 (2-RSO₃) > 63.8 (2-PF₆) > 41.4 °C (2-OTf) for all derivatives with n = 12. The compound 2-BF₄ (n = 16) has the widest temperature range of the smectic-A (SmA) phase (i.e., ΔT_SmA = 234.3 °C), significantly broader than those of other reported ILCs. Also compound 2-NTf₂ (n = 14) was the first phenylpyridinium-based ILC and compound 2-SCN (n = 16) was the room temperature ILC. The X-ray diffraction experiments confirmed the structure of the SmA phase and it showed a strong dependence of bilayer structure with various anions. A linear correlation plot (R² = 0.9643) of the clearing temperatures of compounds 2-X with the calculated effective radius (R_eff) of the anions was obtained.

Full text of DOI:10.1039/c8ce00286j

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CrystEngComm
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and G. Lee, CrystEngComm, 2018, DOI: 10.1039/C8CE00286J.
Volume 18 Number 1 7 January 2016 Pages 1–184
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HIGHLIGHT
Tiddo J. Mooibroek, Antonio Frontera et al.
Towards design strategies for anion–π interactions in crystal engineering
rsc.li/crystengcomm

Page 1 of 34
CrystEngComm
†
Effect of counter ions on the mesogenic ionic N-phenylpyridiniums
View Article Online
DOI: 10.1039/C8CE00286J
a
b
a
Ren−Tzong Wang, Gene−Hsiang Lee, and Chung K. Lai*
Two series of ILCs derived from N-phenylpyridinium 1−2 were prepared and their mesomorphic
properties were investigated. A versatile and effective method was developed to prepare these
ionic compounds 2−X from their precursor chloride 2−Cl. X−ray crystal−structure analyses of
three single crystals revealed that a sandwiched head−to−head or bilayer lamellar structure
induced by H−bonds in the solid state was observed. The anion was proximity intercalated near
the head group. Weak H−bonds were induced and attributed to the formation of mesophases. The
type of counter anions has a significant influence on the stability of the mesophase; ∆TSmA = 221.3
(
2−Cl) > 213.1 (2−SCN) > 173.9 (2−BF
for all derivatives with n = 12. The compound 2−BF
SmA phase (i.e. ∆TSmA = 234.3 °C), significantly broader than those of other reported ILCs. Also
compound 2−NTf (n = 14) was the first phenylpyridinium−based ILC and compound 2−SCN (n
16) was indeed the room temperature ILC. The XRD experiments confirmed the structure of
4
) > 85.4 (2−RSO
3
) > 63.8 (2−PF
6
) > 41.4 °C (2−OTf)
4
(n = 16) has a widest temperature range of
2
=
SmA phase and it showed a strong dependence of bilayer structure with various anions. A linear
2
correlation plot (R = 0.9643) of the clearing temperatures of compounds 2−X with the calculated
effective radius (Reff) of the anions was obtained.
a
Department of Chemistry, National Central University, Chung−Li, Taiwan, Republic of China.
E-mail: cklai@cc.ncu.edu.tw
bInstrumentation Center, National Taiwan University, Taipei, Taiwan, Republic of China.
†
1
13
19
Electronic supplementary information (ESI) available: The H, C and F NMR spectra of
compounds 1-2, the DSC and TGA thermographs of compounds 1-2 and the XRD diffraction plots
of compound 2-BF (n = 12).
4
1

CrystEngComm
Page 2 of 34
View Article Online
DOI: 10.1039/C8CE00286J
Introduction
Most liquid crystals were known or existent as neutral organic compounds, whereas, in
metallomesogens, or so−called metal containing liquid crystals a metal ion(s) was incorporated
into organic moieties. In contrast, ionic liquids are appeared as salts in the liquid states. Ionic
liquids often have a very low vapor pressure, which might be applied as non−volatile organic
1
solvents in organic reactions. The ionic bonds in ionic liquids are usually stronger than the Van
der Waals forces between the molecules of ordinary liquids. Ionic liquid crystals (ILCs) which can
effectively combine the characteristics of liquid crystals with those of ionic liquids have entirely
distinct properties from those of conventional organic molecular compounds. ILCs are often
composed of organic ions and these organic compounds have unlimited structural variations which
2
also are “designable” or “fine−tunable”. Some of important applications in promising fields of
ionic liquid crystals, such as anisotropic ionic conductors,3 solar cells,6−8 batteries, non-linear
−5
9
optics,1
0−12
sensors,13−15 electrofluorescent switches16−17 and membranes for water desalination18
have been investigated and reported.
1
9
Although Knight and Shaw had reported the first pyridinium−based ILCs long ago since 1938;
this field rejuvenated again during the last two decades. The salts of organic cations bearing long
hydrocarbon chains usually have a room temperature or lipid−like bilayer structure due to their
amphiphilic character. On heating, these salts often undergo structural phase transitions, some of
which may lead to mesophase formation. The ionic interactions inherent from ionic compounds
tended to stabilize lamellar mesophases and most of ionic LCs exhibited smectic A phase.
However, they also displayed uncommon mesophases such as columnar20-30 or nematic31−32 phases.
The majority of mesomorphic ionic salts containing organic cations, such as ammonium,24, 33-34
imidazolium,2
3, 25, 35−38
pyridinium, pyrazoliums, phosphonium, pyrylium and thiopyrylium,
39
40
41
21
26
27, 42
dithiolium and guanidinium
were reported. Mesogenic compounds containing cationic
2n+1NH +
Cl were the largest groups amongst ILCs. Few
−
ammonium salts, such as the simplest C
n
H
3
extensive reviews4
3−46
for these thermotropic ILCs were reported.
2

Page 3 of 34
CrystEngComm
While original researches about pyridinium−based ILCs I−II were mainly focused on the
View Article Online
DOI: 10.1039/C8CE00286J
i
r
halide salts,4
7−53
other known examples containing counter anions, such as ROSO −
, PF −
, PdCl
2−,
3
6
4
picrates, sulfonates, cholates and etc were also reported.2
8, 54−58
All these known mesogenic
compounds have N−alkyl chains substituted on the pyridinium, and most of these ILCs gave
smectic A phases. A model of an ionic bilayer structure formed by anions sandwiched between the
pyridinium rings in the mesophases was proposed.47, 50, 53 A systematic investigations to dissect the
possible electronic contribution in different types of ILCs, so far is more lacking.
Y
N
X
Z
Y
N
X
Z
-
,
r
B
CF SO3
:
=
=
=
r
,
RSO PF MX42
,
,
II X
Y
Z
:
=
=
=
I X
Y
Z
B
3
3
6
,
,
,
,
H CN CH
CH3 R
R
OH CH
R
3
3
,
In order to understand the steric hindrance, correlation of the alkyl chain lengths and/or the
counter anions on the formation of the mesophases in such type of ionic pyridinium−based ILCs,
in this work a systematic study for a total number of seventeen ionic compounds was investigated.
Among them, two types of ionic structures were constructed; one series has flexible alkyl chains
incorporated in counter anion (i.e. 1−RSO
series has various anions incorporated in counter anion (i.e. 2−X; X = Cl, OTf, SCN, BF
NTf , RSO ). These rigid−core with N−phenylpyridinium−based structures were structurally
3
) or in counter cation (i.e. 2−RSO
3
), and the second
4
, PF
6
,
2
3
5
9−66
distinct from the previously reported rigid−cores.
Though a few mesogenic examples were
reported; no single crystallographic analysis was yet resolved to correlate their relationships
6
7
between the structures and mesophases observed. A review focused on hydrogen bonding in
ionic liquids was reported by P. A. Hunt. Three single crystals of mesogenic compounds 1‒RSO
3
(
n = 14), 2‒PF
6
(n = 12) and 2‒NTf (n = 14) were obtained, and their single crystal and
2
molecular structures were resolved. Among them, the compounds 2−SCN (n = 12) was indeed a
room temperature ionic ILC.
3

CrystEngComm
Page 4 of 34
View Article Online
DOI: 10.1039/C8CE00286J
Results and Discussion
Synthesis and Characterization
The synthetic routes for compounds 1−2 are shown in Scheme 1. The precursors, N-phenyl
pyridinium chloride 1−Cl and N-(4-alkoxyphenyl)pyridinium chloride 2−Cl were prepared
according to the literatures.6
8−71
Methanol was used as a phase−transfer medium to replace the
Na, NaBF , KPF
O was added to their precursors 1−Cl or 2−Cl dissolved in
(1/9). The cloudy or milky solution turned clear solution after 30 min. The
reaction was continuously stirred at 30 °C for 3 h. These ion−exchanging reactions were
monitored by Alumina TLC plate with an eluent of MeOH/CH Cl (5/95) in which the retention
factor (R ~0.8) of product was higher than R ~0.2 of their precursor. The organic layer was
passed through a short Al flash column. The products isolated as off−white solids were
chloride into another soft anion. The metal salt solution, for example RSO
LiOtf, LiNTf or KSCN dissolved in H
CH OH/CH Cl
3
4
6
,
2
2
3
2
2
2
2
f
f
2
O
3
1
13
19
obtained after recrystallization from methanol, isopropanol or ethyl acetate. The H, C or F
1
NMR was used to identify their structures; for example, on H‒NMR, all PyH−peaks for
pyridinium−based derivatives 1−X and 2−X were differentiated with their precursors 1−Cl and
2
2
−Cl. The individual peak integration of pridinium and alkylsulfonate for either 1−RSO
3
or
−RSO was equivalently obtained, confirming the stoichiometric coefficient for each moiety of
3
1
3
ion pair. On C NMR spectra, the quartet peaks appeared at δ = 119.88‒120.78 ppm (J =
¯
3
20.4‒321.3 Hz) assigned to the −CF
3
group proved the expected TfO and Tf
2
N¯ moieties.
1
9
Furthermore, on F NMR spectra, for example, the characteristic peaks appeared at δ = −154.91 ~
¯
¯, J
−
155.16 and δ = −154.85 ~ −155.10 (singlet, for BF
4
in CDCl
3
), δ = −72.44 (doublet, for PF
6
¯
=
710.1–710.4 Hz in DMSO–d
6
), δ = −81.53 (singlet, for OTf in CDCl
3
) and δ = −82.02 ~ −82.06
¯
(
singlet, for NTf
2
in CDCl ) identified and confirmed all of the fluorine−containing compounds.
3
Positive (or negative) ion moiety was recorded by the ESI−MS to confirm the target structures.
4

Page 5 of 34
CrystEngComm
O N
2
View Article Online
DOI: 10.1039/C8CE00286J
+
N
Cl
NO2
a
O N
2
H N
N
NO2
H N
2
OR
2
Cl
3
c
b
N
N
OR
Cl
Cl
-
-
1
Cl
2 Cl
d
e
N
N
OR
,
RSO3
-
X
-
,
,
,
,
=
1
RSO3
2 X; X BF4 PF6 OTf NTf RSO3 SCN
2
.
,
o
,
,
cheme 1 Rea ents an con itions; a tirre in acetone 55
S
7
g
d
d
S
)
d
,
C
1
8
h
(
,
-
o
,
7%; b Dimethylacetamide stirred at 90 95 C 24 h 43%; c Dimethyl
(
)
(
)
,
-
o
,
,
,
.
,
acetami e stirre at
;
Aqueous R
Na 1 1 eq
SO3
)
d
d
90 9
l
5
C
12 h 5
8%
h
d
( )
(
o
,
,
-
stirre in
; e Aqueous NaBF ;
5
9 96%
d
C
H
O /C 2C
H
H
1
(
/9 30 C 3
3
2
)
( )
rre
4
,
,
,
,
. - .
,
KPF LiOTf LiNTf RSO Na KSCN 3 0 9 0 eq sti d i CH OH/CH Cl
/9 30 C 3 h 95 96%
n
6
2
3
(
)
3
2
2
,
o
,
,
-
.
1
(
)
Single crystal and molecular structures of three compounds 1‒RSO
and 2‒NTf (n = 14)
Three single crystals of the mesogenic compounds 1‒RSO
‒NTf (n = 14) were obtained by slow vaporization from the mixed solvent of
3
(n = 14), 2‒PF (n = 12)
6
2
3
(n = 14), 2‒PF (n = 12) and
6
2
2
hexane/dichloromethane/ethyl acetate at room temperature and their structures were resolved.
Table 1 lists their crystallographic and structural refinement data. They crystallize in an
orthorhombic Pbcn for 1‒RSO
14). One water molecule was trapped in the crystal lattice in 1‒RSO
is not included, all three pyridinium can be considered as linear structures. The molecular lengths
were ca. 22.80 (for 1‒RSO , C3−C25), 22.89 (for 2‒PF , C3−C23) and 25.62 Å (for 2‒NTf
C21−C25 atom), shown in Fig. 1. A relatively large dihedral angle of ca. 38.3−40.6° between
3
(n = 14), and triclinic P−1 both for 2‒PF
6
(n = 12) and 2‒NTf (n
2
=
3
(n = 14). If counter anion
3
6
2
,
5

CrystEngComm
Page 6 of 34
pyridine and phenyl ring of these phenylpyridiniums are observed. Three counter ions,
View Article Online
DOI: 10.1039/C8CE00286J
−, PF
−
and 2‒NTf were all orderly intercalated between the pyridine layers.
−
(
tetradecyl)SO
3
6
2
Fig. 1 Three ORTEP drawings for crystals 1−RSO
−NTf (n = 14, bottom) with the numbering schemes, and thermal ellipsoids of non−hydrogen
atoms are drawn at the 50% probability level.
3
(n = 14, top), 2−PF
6
(n = 12, middle) and
2
2
Table 1 Crystallographic data for three single crystals 1−RSO
3
, 2−PF
6
and 2−NTf
2
.
Crystals
1−RSO
3
(n = 14)
2−PF
6
(n = 12)
2−NTf (n = 14)
2
Empirical formula
Formula weight
Temperature (K)
Crystal system
C
25
H
41NO
4
S
C
23
H
34
F
6
NOP
C
27
H
38
F
6
N
2
O S
5 2
451.65
200(2)
Orthorhombic
485.48
250(2)
Triclinic
648.71
200(2)
Triclinic
6

Page 7 of 34
CrystEngComm
Space group
Pbcn
P-1
P-1
View Article Online
DOI: 10.1039/C8CE00286J
Unit cell dimensions
a = 57.9542(14)
b = 8.3909(2)
c = 10.5626(3)
α = 90°
β = 90°
γ = 90°
5136.5(2) Å3
8
8.4477(3)
10.1370(3)
29.0003(8)
97.1637(10)°
91.7536(12)°
94.3756(11)°
2454.83(13)
4
10.5341(2)
10.5341(2)
38.1037(9)
80.3923(10)°
83.5583(10)°
76.8971(10)°
7805.1(3)
Volume
Z
Density (calculated) (Mg/m )
θ range for data collection ( )
Final R1, wR2
10
3
1.168
3.050 to 69.981
0.0291, 0.0839
1.314
3.074 to 69.989
0.0508, 0.1347
1.380
2.258 to 69.999
0.0767, 0.2098
o
H−bonds and Coulombic forces were found to be dominating in these crystal lattices. Indeed,
H−bonds with a weak to medium−strength in three crystal lattices were observed; for examples,
H−bonds C−H…O of pyridinium−H and sulfonate−O anion or hydrated water in crystal 1−RSO
3
,
H−bonds C−H…F of pyridinium−H and phosphate−F in crystal 2−PF
pyridinium−H and triflic imide−O in crystal 2−NTf (n = 14) were all observed. These H−bond
lengths were ranged from ca. 1.955−2.470 Å (1−RSO ), 2.536−2.588 Å (2−PF ) and 2.348−2.578
Å (2−NTf ) (Fig. 2). Some H−bonds observed between cations and anions in these three crystals
are listed in Table 2.
6
and H−bonds C−H…O of
2
3
6
2
Fig. 2 H−bonds (H…O, F…H) observed in crystals 1−RSO
and 2−NTf (n = 14, right).
3
(n = 14, left), 2−PF (n = 12, central)
6
2
7

CrystEngComm
Page 8 of 34
Table 2 H−bonds(D−H…A) observed between cations and anions in three crystals.
View Article Online
DOI: 10.1039/C8CE00286J
Compds.
H−bonds
distance (Å)
angle (o)
1
−RSO
3
(n = 14)
O4−H4A−O1
O4−H4B−O3
C5−H5−O2
C7−H7−O2
C4−H4−O4
C11−H11−O3
C1−H1−O2
C1−H1‒F7
1.955
2.093
2.314
2.352
2.372
2.380
2.470
2.536
2.559
2.569
2.588
2.348
2.446
2.544
2.544
2.578
169.7
170.4
132.8
159.5
157.0
159.1
130.0
157.8
160.2
121.3
119.9
168.1
122.8
132.5
168.4
121.2
2
2
−PF (n = 12)
6
C4−H4‒F4
C2−H2‒F12
C4−H4‒F10
C7−H7‒O11
C3−H3‒O23
C1−H1‒O13
C11−H11‒O10
C5−H5‒O9
−NTf (n = 14)
2
Coulombic forces and intermolecular π−π interactions in these ILCs were also crucial, shown in
δ+
Fig. 3. Considering the formal charge between more positive N atoms and nearby standing
δ−
δ−
negative F (or O ) atoms, the crystal packing model was mainly driven by the Coulombic
interaction. Crystallographic data indicated that the distance of the Coulombic force when packed
with a smaller anion was ca. d = 3.194−4.443 Å in 1−RSO
3
or ca. d = 3.258−4.500 Å in 2−PF6,
which was lightly shorter than that ca. d = 3.925−4.514 Å packed with a larger counter anion in
2
−NTf
2
, as expected. Furthermore, the distance between neighboring phenylpyridiniums in
and 2−PF was ranged from d = 8.391−8.448 Å due to the counter anions intercalated.
with a distance ranging from d = 3.837
4.117 Å. (Fig. 3). However, the Coulombic forces in three crystals were much weaker than
1
−RSO
3
6
Weak intermolecular interactions were observed in 2−NTf
2
−
+
−
H−bonds. The distances of Coulombic forces were ranged from d = 3.194−4.443 Å (atom N …O
+
−
+
−
in 1-RSO
3
), d = 3.258−4.500 Å (atom N …F in 2-PF
). In contrast, the distances of H−bonds (D−H…A) ranged from d = 1.955−2.470 Å in
, d = 2.536−2.588 Å in 2-PF and d = 2.348−2.578 Å in 2-NTf .The distance of
6
) or d = 3.925−4.514 Å (atom N …O in
2
-NTf
2
1
-RSO
3
6
2
8

Page 9 of 34
CrystEngComm
intermolecular interactions between of Py−Py rings (d = 3.974 − 4.080Å) and Ph−Ph rings (
V
d
iew Article Online
=
DOI: 10.1039/C8CE00286J
3
.959−4.117Å) in 2−NTf was slightly longer than that of Py−Ph rings (d = 3.837−3.924 Å).
2
Fig. 3 Coulombic forces (red dash line) and intermolecular interactions (blue dash line) observed
in 1−RSO (n = 14, left), 2−PF (n = 12, middle) and 2−NTf (n = 14, right) in the crystal lattices.
3
6
2
In crystal 1-RSO
3
(n = 14) and 2−PF (n = 12), each anion was packed by a sandwiched
6
head−to−head arrangement, which was then alternatively aligned by a bilayer lamellar structure.
All terminal alkoxy chains were highly interdigitated between layers. However, the molecular
shape of 1-RSO
3
(n = 14) was described as V−shaped, while that of 2−PF
6
(n = 12) was instead
considered as I−shaped. In contrast, all cations and anions in 2−NTf
2
(n = 14) between or
above/below the neighboring layers were preferably packed in a bilayer lamellar structure. Also,
all alkoxy chains were also highly interdigitated by a style of layer−by−layer and head−to−tail (see
Fig. 4).
9

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Page 10 of 34
View Article Online
DOI: 10.1039/C8CE00286J
Fig. 4 Molecular arrangements observed in 1−RSO
3
(top left, green tetrahedron represents CSO ),
3
2
−PF
6
(top right, green octahedron represents PF
6
) and 2−NTf (bottom, green tetrahedron
2
represents is NSO
2
C) in the crystal lattices. All alkoxy chains were highly interdigitated between
the layers.
Mesomorphic properties and thermal stability of compounds 1−RSO
SCN, RSO , BF , PF , NTf
The thermal behavior of the compounds 1−RSO
NTf ) was investigated by polarized optical microscopy (POM) and differential scanning
calorimetry (DSC). The transition temperatures and enthalpies are listed in Table 3. All
compounds 1−2 exhibited mesogenic behavior, which are expected for rod−like molecules 1−2.
Two derivatives in compounds 2−PF (n = 10) and 2−NTf (n = 14) gave monotropic behavior,
whereas all other compounds 2−X exhibited enantiotropic behavior. For the series of compounds
−RSO , DSC data indicated that the melting temperature remained at 91.0−107.0 °C while the
clearing temperature increased with carbon length; i.e. Tcl = 133.0 (n = 12) < 157.0 (n = 14) <
3
and 2−X (X = Cl, OTf,
3
4
6
2
)
3
and 2−X (X = Cl, OTf, SCN, RSO
3
, BF
4
, PF ,
6
2
6
2
1
3
2
02.6 °C (n = 16). The temperature range of SmA phases increased with carbon length; ∆TSmA
=
5
4.0 (n = 12) < 77.0 (n = 14) < 138.1 °C (n = 16) on cooling process. The derivative n = 16 has a
widest temperature of ∆TSmA = 138.1 °C, indicating that this derivative has a most appropriate
10

Page 11 of 34
CrystEngComm
aspect ratio d/l required for the formation the mesophases.
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DOI: 10.1039/C8CE00286J
The mesophase was further characterized by POM; a focal−conic texture (Fig. 5a) typically
observed for SmA phases was observed under POM, and theses textures were often accompanied
by a larger area of homeotropic behavior. These SmA phases were confirmed as bilayer structures
by power XRD experiments (see discussion later). Interestingly, the DSC data indicated that the
clearing temperature of compounds 1−RSO
3
(n = 12) was lower than that of compounds 2−RSO
3
(n = 12), i.e. Tcl = 133.0 < 199.0 °C. One more dodecyloxy chain substituted on core phenyl group
in 2−RSO
in 2−RSO
3
3
facilitated or enhanced the formation of the mesophase. The temperature of mesophase
(n = 12) was wider than that in 1−RSO (n = 12), i.e. ∆Tmeso = 85.4 > 54.0 °C on
3
cooling process.
For the compounds 2−X, seven anions (X = Cl, OTf, SCN, RSO
3
, BF
4
, PF
6
, NTf ) were
2
prepared. Surprisingly, all compounds 2−X were mesogenic regardless of the type of counter
anions. However, DSC data indicated that their transition temperatures observed by each counter
anion were very sensitive to the size or/and shape of the counter anions. The clearing temperatures
of compounds 2−X (for all derivatives n = 12) decreased in the order of Tcl = 239.0 (X = Cl) >
2
22.8 (SCN) > 216.8 (BF
counter anions, X = Cl, BF
anions might favor the molecular arrangement or packing in the crystal or liquid crystal states.
Futhermore, in the series of compounds 2−BF , the melting temperatures of all derivatives
4
) > 199.0 (RSO
3
) > 167.2 (PF
6
) > 108.8 °C (OTf) (Fig. 6). The three
4
and PF were considered as sphere group or moieties and the smaller
6
4
remained at Tmelt = 83.7− 88.6 °C, whereas their clearing temperatures of compounds increased
significantly with carbon length; Tcl = 170.1 (n = 10) < 216.8 (n = 12) < 252.9 (n = 14) < 272.9 °C
(
n = 16). The mesophase was identified by POM; an oily streak (Fig. 5b) was observed under
POM when cooled from their isotropic states. The temperature range of SmA phases in
compounds 2−BF also increased with carbon length; ∆TSmA = 116.0 (n = 10) < 173.9 (n = 12) <
10.1 (n = 14) > 234.3 °C (n = 16) on cooling process. The derivative 2−BF (n = 16) has a widest
temperature of ∆TSmA = 234.3 °C, which is not commonly observed in organic neutral compounds.
4
2
4
11

CrystEngComm
Page 12 of 34
.
a
- .
Table 3 The phase t
rans ons an en
iti
th lpi
a
es o com oun s
1 2
d
f
p
d
View Article Online
DOI: 10.1039/C8CE00286J
.
.
b
133 0b
9
1 0
-
=
I
I
SmA
SmA
SmA
1
RSO3;
n
12
r
C
.
.
b
b
b
b
b
7
2 0
126 0
.
.
1
07 0
157 0
r
r
r
r
1
4
6
C
C
C
C
.
.
b
7
8 0
155 0
.
.
.
.
1
01 5 14 0
202 6 0 72
(
)
(
)
1
.
.
.
.
I
I
I
6
2 8 31 1
200 9 0 97
(
(
)
)
)
)
.
.
.
.
8
8 3 11 2
170 1 1 33
( )
-
(
=
SmA
2
BF4;
n
10
.
.
.
.
5
8
4
3 1 7 87
169 1 (1 38)
(
.
.
.
.
3 7 9 96
216 8 (1 40)
(
)
)
m
A
m
A
m
A
1
2
4
.
.
S
S
S
.
.
1 9 4 17
215 8 1 45
( )
(
.
.
.
.
8
6 4 10 2
252 9 (1 68)
(
)
1
C
C
r
.
.
.
.
I
I
I
I
I
I
4
0 7 3 62
250 8 1 85
(
(
)
)
)
)
.
.
.
.
8
8 6 18 3
272 9 1 60
(
(
)
r
1
6
.
.
.
.
3
5 6 12 7
269 9 (1 55)
(
.
.
1
26 7 22 3
( )
-
=
r
r
r
n
C
C
C
.
.
.
.
2
PF6;
10
m
m
1
05 1 16 8
S
S
A
124 4 0 91
(
(
)
)
)
)
.
.
.
.
1
24 3 26 7
167 2 1 23
(
(
)
)
12
14
1
6
.
.
A
.
.
1
02 0 9 24
165 8 1 23
(
(
.
.
.
.
1
20 9 28 4
221 3 1 55
(
(
)
)
m
S
S
A
A
.
.
.
.
8
8 4 5 74
217 1 1 21
(
(
)
)
)
)
)
.
.
.
.
1
21 8 32 5
228 3 1 25
(
(
)
r
r
m
C
.
.
.
.
8
6 8 5 48
224 1 1 25
(
(
)
.
.
5
6 8 37 8
(
-
=
C
.
.
I
I
NTf2;
n
1 4
.
.
m
A
2
S
3
6
5
4 4 47 2
45 4 0 80
( )
(
)
.
.
.
.
0 5 1 62
77 8 (1 04)
(
)
r
r
SmA
1
6
C
.
.
.
.
0 1 1 22
76 6 1 09
(
(
)
)
)
)
.
.
.
239 0b
5
0 8 6 85
(
-
=
=
m
A
Cl;
n
n
12
12
C
S
Id
2
.
.
.
b
1
4 7 5 94
236 0
(
.
.
.
.
-
80 1 32 2
(
)
)
108 8 0 83
(
)
2
O
Tf;
r
C
r
C
r
C
S
S
S
m
A
m
A
m
A
I
I
I
.
.
.
.
6
6 3 33 7
107 7 (0 90)
(
.
.
.
.
1
22 6 24 8
199 0 (1 73)
-
-
(
)
)
)
=
=
RSO3;
n
n
12
12
.
.
.
.
2
1
11 8 23 6
197 2 1 75
(
(
)
.
.
.
.
2
9 6 6 19
222 8 1 10
(
(
)
2
SCN;
.
.
.
.
5
80 0 55
218 9 (1 25)
(
)
a: n s e car on num er n e a ox c a ns
,
r
=
cr s a
y t l S
,
=
m
smec c
ti A
i
th
b
b
i
th lk
y
h i
,
C
A
,
=
.
,
ase I isotro ic hase Tem eratures taken on secon heatin coolin c cle
ph
p
p
p
d
g/
un ;
g
y
o
.
.
were e erm ne
a a scan ra e o
f 10 C/
m n
i
n
a
mo
l
d t
i
d by DSC
t
t
E th lpy it kJ/
.
b
: o serve
b
d by POM
12

Page 13 of 34
CrystEngComm
View Article Online
DOI: 10.1039/C8CE00286J
Fig. 5 Optical textures observed. (a) Focal−conic by 1−RSO
by 2–BF (n = 10) at 125 °C; (c) Oily streak by 2−PF (n = 12) at 140 °C; (d) Oily streak by
−NTf (n = 16) at 70 °C; (e) Oily streak by 2−Cl (n = 12) at 185 °C; (f) Oily streak by 2−OTf (n
12) at 80 °C; (g) Homeotropic by 2−OTf (n = 12) at 110 °C; (h) Oily streak by 2−RSO (n = 12)
at 140 °C; (i) Oily streak by 2−SCN (n = 12) at 210 °C.
3
(n = 12) at 105 °C; (b) Oily streak
4
6
2
2
=
3
On the other hand, compounds 2−PF
−BF . The size of hexagonal PF was a larger moiety than that of tetrahedral BF
effect caused by the larger PF should be expected in the LC or/and crystal states. The shorter
derivative n = 10 showed monotropic behavior; a transition from Cr−to−isotropic occurred at Tcl
6
showed similar mesogenic behavior with compounds
2
4
6
4
and the packing
6
=
1
26.7 °C was observed on heating process. However, other three derivatives with longer alkoxy
chains n = 12, 14, 16 exhibited enantiotropic behavior. The clearing temperatures showed similar
trend to those of compounds 1−RSO
3
, 2−BF
4
and 2−PF ; the clearing temperatures increased with
6
carbon length; Tcl = 126.7 (n = 10) < 167.2 (n = 12) < 221.3 (n = 14) < 228.3 °C (n = 16) on
heating process. The temperature range of mesophase showed the increasing trend with carbon
length as follows; ∆TSmA = 19.3 (n = 10) < 63.8 (n = 12) < 128.7 (n = 14) < 137.3 °C (n = 16) on
cooling process. An oily streak texture (Fig. 5c) observed under POM when cooled from their
13

CrystEngComm
Page 14 of 34
isotropic states confirmed the SmA phases. In contrast, compounds 2-NTf
2
led to the smalle
View Article Online
DOI: 10.1039/C8CE00286J
s
t
temperature range of SmA phases (Fig. 5d) among all counter anions; ∆TSmA = 11.0 (n = 14) <
2
6.5 °C (n = 16) on cooling process. Also, their clearing temperatures were the lowest among the
all compounds 2−X; Tcl = 56.8 (n = 14) < 77.8 °C (n = 16). NTf −
has an unsymmetric structure
2
and often considered as a bulky moiety, and the lower clearing temperature in 2−NTf
2
was
probably attributed to its weaker Coulombic force. No example of ionic liquid crystal derived
72
from N-alkylpyridinium NTf ¯ salts was known.
2
Fig. 6 Bar graphs showing the phase behavior of compounds 2−X (all n = 12). All temperatures
were taken from cooling process.
All compounds 2−X (X = Cl, OTf, RSO
−Cl has highest clearing temperatures than those of other three compounds 2−X (X = OTf, SCN
and RSO ), i.e. Tcl = 239.0 (X = Cl) > 222.8 (SCN) > 199.0 (RSO ) > 108.8 °C (OTf).
Interestingly, the temperature range of SmA phase also showed the same decreasing order of i.e.
SmA = 221.3 (X = Cl) > 213.1 (SCN) > 85.4 (RSO ) > 41.4 °C (OTf) on the cooling process (Fig.
). The mesophases were all identified as smectic A phases based on optical textures observed
3
and SCN) with an n = 12 exhibited SmA phases. The
2
3
3
T
3
6
under microscope. (Fig. 5f−i)
In order to understand the possible correlation between the size/shape of the anions with the
transition temperatures in such ILCs system, a plot of clearing temperatures with the size of anion
14

Page 15 of 34
CrystEngComm
moieties was obtained. The effective ionic radii (Reff) of each anion are calculated by equatioVie
n
w Article Online
DOI: 10.1039/C8CE00286J
:
V
3
=
(4/3)(πR ) assuming that the ions studied have spherical shapes. The calculated effective radii
−
73
−
74
−
75
−
76
(R
eff) of anions are as follows: Cl = 1.67 Å, SCN = 1.93 Å, BF
4
= 2.05 Å, PF
6
= 2.59 Å,
−
76
−
77
2
TfO = 2.75 Å and NTf
2
= 3.72 Å. Interestingly, a good linear plot (R = 0.9643, Fig. 7)
between the clearing temperatures and effective radii of anions was obtained which was in good
agreement with previous reports.2
9, 78−79
Fig. 7 Correlation of clearing temperature (Tcl) with calculated effective radius (Reff) of the
anions in compounds 2−X (all n = 12).
The thermal stability of the compounds 2−X (X = BF
4
, PF ) was performed by
6
thermogravimetric analyses (TGA) under nitrogen atmosphere, shown in Fig. 8. The relative
stability of compounds 2−X was not affected by the carbon lengths of the alkoxy group. All
compounds show relatively good thermal stability at the temperature higher than 300 °C. The
decomposition temperatures of compounds 2−BF
while those of compounds 2−PF were slightly lower at Tdec = 313.0−329.0 °C for a 5% weight
loss. On the other hand, more thermal−resistant ILCs can be obtained by counter anions, T = 372
X = NTf ) > 346 (TfO) > 330 (BF ) > 312 (PF ) > 305 (RSO ) > 281 (SCN ) > 239 °C (Cl).
4
were ranged from Tdec = 333.0 −338.0 °C,
6
d
(
2
4
6
3
15

CrystEngComm
Page 16 of 34
View Article Online
DOI: 10.1039/C8CE00286J
Fig. 8 TGA thermograms of compounds 2−BF
4
(left) and 2−PF (right) under nitrogen gas at a
6
-1
heating rate of 10.0 °C min .
Powder X−ray diffractions and packing arrangements
Variable−temperature powder XRD diffraction experiments were performed to confirm the
structure of SmA phases observed by compounds 1−RSO and 2−X (X = Cl, NTf , SCN, BF
OTf, RSO ). All samples (except for 2-Cl) were first heated above their clearing temperatures,
3
2
4
, PF ,
6
3
cooling down at a mesophase temperature and the diffraction data then collected. A summary of
diffraction data was listed in Table 4. In all cases, the XRD patterns show a lamellar structure
indicated by the indexed as the 001, 002 and 003 in the lower angle region. For example, for
compounds 2−Cl (n = 12) at T = 150.0 °C a diffraction pattern with one strong peak at 40.6 Å and
three much weaker peaks at 20.3, 13.5 and 10.2 Å was observed (shown in Fig. 9). These
diffraction peaks assigned as index 001, 002, 003 and 004 were typically characteristics of layer
structures observed for SmA phase. The d−spacing of 40.6 Å was longer than molecular length for
all three crystals L = 22.0−25.60 Å, obtained by crystallographic data appeared that all molecules
were arranged as a bilayer structures in the mesophases. X−ray crystal−structure analyses of three
single crystals revealed that a sandwiched head−to−head or bilayer lamellar structure formed by
H−bonds in the solid state was observed. The anion was oriented proximity to the head group at a
larger distance. Other compounds also showed the similar diffraction pattern as compound 2−Cl.
Three other compounds 2−NTf
2
, 2−SCN and 2−BF displayed a similar diffraction pattern with
4
16

Page 17 of 34
CrystEngComm
one strong peak with a d−spacing of 38.1, 36.6 and 34.1 Å assigned as indices 001 at lower
V
a
ie
n
w
g
A
l
rticle Online
e
,
DOI: 10.1039/C8CE00286J
followed by a weaker peak with a d−spacing of 19.0 Å, 18.2 Å and 18.1 Å at higher angle
assigned as indices 002. Another set of weaker peaks at a d−spacing of 12.7 Å, 12.1 Å and 12.1 Å
assigned as indices 003 was also observed. A broad halo peak at ca. 4.60 Å for all three
compounds was also observed.
Table 4 Detailed indexation by XRD for compounds 1−2.
Compds
Mesophase
temp.
d−Spacing (Å)
obs. (calcd.)
Miller
indices
a
2
−Cl (n = 12)
SmA at 150 °C
40.6 (40.6)
001
002
003
004
halo
001
002
003
halo
001
002
003
halo
001
002
003
halo
001
halo
001
002
halo
001
002
halo
001
halo
2
1
1
4
0.3 (20.3)
3.5 (13.5)
0.2 (10.2)
.60 (br)
2
2
2
−NTf
2
(n = 14)
SmA at 40 °C
SmA at 150 °C
SmA at 140 °C
38.1 (38.1)
1
1
4
9.0 (19.1)
2.7 (12.7)
.60 (br)
−SCN (n = 12)
36.6 (36.6)
1
1
4
8.2 (18.3)
2.1 (12.2)
.60 (br)
−BF
4
(n = 12)
(n = 12)
36.1 (36.1)
1
1
4
8.1 (18.1)
2.1 (12.0)
.60 (br)
2
−PF
6
SmA at 140 °C
SmA at 90 °C
34.4 (34.4)
.70 (br)
33.7 (33.7)
4
2
−OTf (n = 12)
1
4
6.9 (16.9)
.70 (br)
2
−RSO
3
3
(n = 12)
(n = 12)
SmA at 150 °C
SmA at 120 °C
31.5 (31.5)
1
4
5.8 (15.8)
.70 (br)
1
−RSO
28.1 (28.1)
.60 (br)
4
a: compound 2-Cl was slowly heated up to T = 140 °C, remained for a few min.,
and the diffraction data were then collected due to partial decomposition at a
temperature higher than its clearing point.
17

CrystEngComm
Page 18 of 34
View Article Online
DOI: 10.1039/C8CE00286J
Fig. 9 The powder X−ray diffraction plots: compound 2−Cl (n = 12, top plot) at 150 °C, 2−BF
4
(n
=
12, middle plot) at 140 °C and 2−SCN (n = 12, bottom plot) at 150 °C.
A d = 31.5 Å obtained by compound 2−RSO
−RSO , as expected. The single crystallographic data indicated that the molecular length of
N-phenyl pyridinium tetradecylsulfonate in 1−RSO was 22.8 Å and N-(4-tetradecyloxyphenyl)
pyridinium in 2−RSO was estimated as 25.6Å from single crystallographic data of 2−NTf . A
broad halo peak appeared at 4.60 and 4.70 Å was also observed for both compounds. This broad
3
is slightly larger than d = 28.1 Å of compound
1
3
3
3
2
18

Page 19 of 34
CrystEngComm
and diffused peak corresponded to liquid−like correlations between alkoxy chains. A schem
V
a
ie
t
w
icArticle Online
DOI: 10.1039/C8CE00286J
representation of molecular organization proposed in SmA phase by compounds 2−X is shown in
Fig. 10.
L
Fig. 10 Schematic representation showing that the d−spacing (d ) obtained by the larger anion was
S
shorter than that (d ) by the smaller anion in SmA phases. All alkyl chains in the compounds with
a larger anion were more interdigitated than that in compounds with smaller anion.
An interesting feature for the correlation between the d−spacing with the size of the counter
anions in 2−X was observed; the d−spacing decreased in the order of d = 40.6 (2−Cl) > 38.1
(2−NTf
2
) > 36.6 (2−SCN) > 36.1 (2−BF
4
) > 34.4 (2−PF
6
) > 33.7 (2−OTf) > 31.5 (2−RSO ) >
3
−
−
−
were the smaller anions, PF −
−
2
8.1 Å (1−RSO
3
). The Cl , SCN and BF
4
6
, TfO the middle, while
the RSO −
was the lager anions. This correlation in layer thickness might be attributed to the
3
Coulombic force by cation and anion and the van der Waals by alkoxy chains. On the other hand,
−
−
−
a larger counter anion such as PF
the alkoxy chains, leading to a smaller layer thickness. Another interesting feature is that the
distance of pyridinium−based bilayer in compounds 2−BF and 2−PF was in good linearly
correlation with increasing temperature in mesophase (Fig. 11).
6
, TfO or RSO would facilitate higher interdigitation between
3
4
6
19

CrystEngComm
Page 20 of 34
View Article Online
DOI: 10.1039/C8CE00286J
Fig. 11 Lamellar thickness data observed by temperature−dependent XRD: 2−BF
4
(solid red line;
n = 12) and 2−PF (dash red line; n = 12).
6
Conclusions
Two different types of ionic mesogens with rigid-cores of N-phenylpyridinium salts 1 and
N-(4-alkoxyphenyl)pyridinium salts 2 were investigated. A bilayer structure with highly
interdigitated alkyl chains in such pyridiniums were supported by the crystal packing analysis of
SC−XRD. Highly symmetric H−bond active sites generated by counter anions indicated by
SC−XRD led to a high clear temperature and wide mesomorphism range. Clearing temperatures
and wider mesophase range increased with elongation of alkyl chain and decrease steadily with
increasing ion radius. The compound 2−BF
4
(n = 16) has a widest temperature range of SmA
(n = 14) was the first phenylpyridinium−
phase (i.e. ∆TSmA = 234.3 °C). Also compound 2−NTf
2
based ILC and compound 2−SCN (n = 16) was the room temperature ILC.
Experimental
Materials
All chemicals and solvents were reagent grade from Aldrich Chemical Co., and solvents were
dried by standard techniques.
Instrumentation
20

Page 21 of 34
CrystEngComm
1
13
19
H, C and F NMR spectra were measured on a Bruker DRS−300. DSC thermographs we
View Article Online
DOI: 10.1039/C8CE00286J
r
e
carried out on a Mettler DSC−822 and calibrated with a pure indium sample. All phase transitions
are determined by a scan rate of 10.0 °C/min. Optical polarized microscopy was carried out on
Zeiss Axioplan two equipped with a hot stage system of Mettler FP90/FP82HT. Elemental
analyses were performed on a Heraeus CHN−Rapid elemental analyzer. The powder diffraction
data were collected from the Wiggle A beam line of the National Synchrotron Radiation Research
Center (NSRRC) with a wavelength of 1.3223 Å. The powder samples were charged in Lindeman
capillary tubes (80 mm long x 0.01 mm thick) purchased from Charles Supper Co. with an inner
diameter of 1.0 mm.
68
Synthesis of N-(2,4-dinitrophenyl)pyridinium chloride 3. The solution of 2,4-dinitrochloro
benzene (10.4 g, 51.3 mmol) and pyridine (4.0 g, 50.6 mmol) was dissolved in acetone (50 mL).
The initially clear reaction mixture became gradually muddy and then was further stirred at 55 °C
for 18 h. The crude solid was collected through filtration and washed with warm acetone.
Compound 3 isolated as white powder was obtained after drying in vacuum oven for 2 h. Yield
1
7
7%; H NMR (300 MHz, DMSO−d
6
): δ 8.43−8.50 (m, 3H, Ar−H & Py−H), 8.94−9.00 (m, 2H,
Py−H), 9.11 (d, 1H, Py−H, J = 2.4 Hz), 9.47 (dd, , 2H, Py−H, J = 5.4, 0.9 Hz).
6
9
Synthesis of N-phenylpyridinium chloride 1−Cl. The mixture of N-(2,4-dinitrophenyl)
pyridinium chloride 3 (2.82 g, 10.0 mmol) and freshly distilled aniline (0.98 g, 10.5 mmol) was
added into N,N-dimethylacetamide (10 mL). The solution of was gently stirred at 90–95 °C for 24
h. The solution was cooled and ethyl acetate (40 mL) was added dropwise at a temperature below
5
.0 °C. The crude product was collected and dried under vacuum. The product isolated as
1
brownish powder was obtained after recrystallization from ethyl acetate. Yield 43 %; H NMR
(
300 MHz, DMSO−d
Py−H, J = 3.3, 4.2 Hz), 8.79 (t, 1H, Py−H, J = 4.5 Hz), 9.36 (d, 2H, Py−H, J = 3.3 Hz). C NMR
75 MHz, DMSO−d ): δ 124.73, 128.18, 130.20, 131.21, 142.79, 144.95, 146.62.
General synthetic preparation of N-phenylpyridinium dodecyloxysulfonate 1−RSO
6
): δ 7.76−7.74 (m, 3H, Ar−H), 7.91−7.89 (m, 2H, Ar−H), 8.31 (dd, 2H,
1
3
(
6
3
(n =12).
21

CrystEngComm
Page 22 of 34
To the suspension of sodium 1-dodecanesulfonate (300 mg, 1.1 mmol) in water (5.0 mL), th
View Article Online
DOI: 10.1039/C8CE00286J
e
solution of 1−Cl (192 mg, 1.0 mmol) dissolved in methanol/CH
added. The solution was stirred, and the reaction was monitored by thin−layer chromatography
Al ) TLC MeOH/CH Cl (5/95); an R ~ 0.8 of product was higher than R ~0.2 of 1−Cl. The
organic layer was passed through a short Al flash column. The crude product was collected
after solvent removed. The product 1−RSO
2
Cl
2
(1/9, 20 mL) was slowly
(
2
O
3
2
2
f
f
2
O
3
3
isolated as fine off−white powder was obtained after
1
recrystallization from ethyl acetate at ice bath. Yield 96%; H NMR (300 MHz, CDCl
3
): δ 0.85 (t,
), 2.71–2.76 (m, 2H,
), 7.63 –7.64 (m, 3H, Ar−H), 7.82−7.85 (m, 2H, Ar−H), 8.40 (dd, 2H, Py−H, J = 6.9, 7.1
3
H, −CH
SO CH
Hz), 8.62 (t, 1H, Py−H, J = 7.5 Hz), 9.30 (d, 2H, Py−H, J = 6.0 Hz). C NMR (75 MHz, CD
δ 14.22, 22.78, 25.56, 29.14, 29.45, 29.55, 29.63, 29.74, 32.01, 52.28, 124.34, 129.57, 130.96,
3
, J = 6.3 Hz), 1.21–1.29 (m, 18H, −CH
2
), 1.73–1.80 (m, 2H, −CH
2
−
2
2
1
3
3
OD):
+
+
1
1
31.77, 142.69, 144.82, 146.49. ESI−HRMS (+ve): m/z calcd for C11
H10N : 156.0808 [M ]; found:
56.0815. ESI−HRMS (−ve): m/z calcd for C12 Sˉ: 249.1530 [Mˉ]; found: 249.1524. Anal.
H
25
O
3
calcd for C23
H35NO
3
•1.5H
2
O: C, 63.85; H, 8.85; N, 3.24; found: C, 63.94; H, 9.12; N, 3.10.
1
N-Phenylpyridinium tetradecylsulfonate 1−RSO
MHz, CDCl ): δ 0.87 (t, 3H, −CH , J = 6.3 Hz), 1.23–1.33 (m, 22H, −CH
CH ), 2.73–2.79 (m, 2H, −SO CH ), 7.63 –7.65 (m, 3H, Ar−H), 7.84−7.87 (m, 2H, Ar−H), 8.41
3
(n = 14). Off−white powder; H NMR (300
3
3
2
), 1.75–1.83 (m, 2H,
−
2
2
2
(dd, 2H, Py−H, J = 6.9, 7.2 Hz), 8.63 (t, 1H, Py−H, J = 7.8 Hz), 9.27 (d, 2H, Py−H, J = 6.3 Hz).
13C NMR (300 MHz, CDCl
): δ 14.24, 22.80, 25.54, 29.14, 29.47, 29.57, 29.65, 29.79, 32.03,
3
5
2.27, 124.35, 129.56, 130.98, 131.80, 142.71, 144.76, 146.51. ESI−HRMS (+ve): m/z calcd for
+
+
C
11
H
10N : 156.0808 [M ]; found: 156.0825. ESI−HRMS (−ve): m/z calcd for C14
H
29
3
O Sˉ:
2
77.1843 [Mˉ]; found: 277.1864. Anal. calcd for C25
H39NO
3
•H
2
O: C, 66.48; H, 9.15; N, 3.10;
found: C, 66.16; H, 9.42; N, 3.03.
1
N-Phenylpyridinium hexadecylsulfonate 1−RSO
3
(n = 16). Off−white powder; H NMR (300
MHz, CDCl
3
): δ 0.88 (t, 3H; −CH
3
, J = 6.3 Hz), 1.35 (br, 26H, −CH
2
), 1.75–1.85 (m, 2H, −CH
2
),
2
.76–2.82 (m, 2H, −SO
2
CH ), 7.66 –7.70 (m, 3H, Ar−H), 7.86−7.89 (m, 2H, Ar−H), 8.43 (dd, 2H,
2
22

Page 23 of 34
CrystEngComm
1
3
Py−H, J = 6.9, 7.2 Hz), 8.63 (t, 1H, Py−H, J = 7.8 Hz), 9.26 (d, 2H, Py−H, J = 5.7 Hz). C
V
N
iew
M
Article Online
R
DOI: 10.1039/C8CE00286J
(300 MHz, CDCl
3
): δ 14.26, 22.82, 25.56, 29.17, 29.49, 29.59, 29.66, 29.82, 32.05, 52.29, 124.36,
1
1
29.58, 131.04, 131.88, 142.72, 144.78, 146.45. ESI−HRMS (+ve): m/z calcd for C11H
10N+:
+
56.0808 [M ]; found: 156.0808. ESI−HRMS (−ve): m/z calcd for C16
H O
31 3
Sˉ: 303.1994 [Mˉ];
found: 303.1988. Anal. calcd for C27
.80; N, 2.88.
H43NO
3
•H O: C, 67.60; H, 9.46; N, 2.92; found: C, 67.52; H,
2
9
7
0
General synthetic preparation of N-(4-dodecyloxyphenyl)pyridinium chloride 2−Cl (n = 12).
The solution of N-(2,4-dinitrophenyl)pyridinium chloride 3 (2.82 g, 10 mmol) and 4-dodecyloxy-
7
1
aniline (3.05 g, 11 mmol) dissolved in N, N-dimethylacetamide (20 mL) was stirred at 90–95 °C
for 12 h. Acetone (50 mL) was dropwise added to the solution at temperature below 60 °C. The
crude product was collected at 0–5.0 °C. The product 2−Cl isolated as off white powder was
1
obtained after recrystallization from methanol. Yield 58%; H NMR (300 MHz, DMSO−d
6
): δ
, J = 6.3, 6.9 Hz),
, J = 6.3 Hz), 7.25 (d, 2H, Ar−H, J = 9.0 Hz), 7.82 (d, 2H, Ar−H, J = 9.0 Hz),
.28 (dd, 2H, Py−H, J = 6.6, 7.5 Hz), 8.75 (t, 1H, Py−H, J = 7.8 Hz), 9.31 (d, 2H, Py−H, J = 5.7
0
4
8
.85 (t, 3H, −CH
3
, J = 6.3Hz), 1.25–1.43 (m, 18H, −CH
2
), 1.73 (dd, 2H, −CH
2
.09 (t, 2H, −OCH
2
1
3
Hz). C NMR (75 MHz, DMSO−d ): δ 13.94, 22.08, 25.43, 28.49, 28.71, 29.00, 31.29, 68.26,
6
115.57, 126.01, 128.07, 135.72, 144.75, 145.96, 160.51. ESI−HRMS (+ve): m/z calcd for
+
+
C
23
H
34NO : 340.2635 [M ]; found: 340.2613. Anal. calcd for C23
H
34ClNO•2H O: C, 67.05; H,
2
9
.30; N, 3.40; found: C, 66.95; H, 9.21; N, 3.24.
General synthetic procedures of N-(4-dodecyloxyphenyl)pyridinium salts 2–X (X = BF
OTf, NTf , RSO , SCN)
N-(4-Dodecyloxyphenyl)pyridinium tetrafluoroborate 2–BF
188 mg, 0.5 mmol) dissolved in methanol/CH Cl (1/9, 10 mL), a 10% aqueous solution of
sodium tetrafluoroborate (5.0 g, 4.6 mmol) was added. The solution was stirred at room
temperature for 3 h. Reaction was monitored by Alumina (Al ) TLC plate in MeOH/CH
5/95); an R ~0.7 of product was higher than R ~0.2 of 2-Cl. The organic layer was passed
4
, PF
6
,
2
3
4
(n = 12). To the solution of 2-Cl
(
2
2
2
O
3
2
Cl
2
(
f
f
23

CrystEngComm
Page 24 of 34
through a short Al
2
O
3
flash column. The crude product was collected after solvents were remVie
o
w
v
A
e
rti
d
cle Online
.
DOI: 10.1039/C8CE00286J
The product 2−BF
4
isolated as fine white powder was obtained after recrystallization from
1
isopropanol/ethyl acetate. Yield 96%; H NMR (300 MHz, CDCl
3
): δ 0.87 (t, 3H, −CH
), 3.99 (t, 2H, −OCH , J = 6.3 Hz), 7.07
d, 2H, Ar−H, J = 9.0 Hz), 7.62 (d, 2H, Ar−H, J = 9.0 Hz), 8.18 (dd, 2H, Py−H, J = 6.6, 7.5 Hz),
3
, J = 6.3
Hz), 1.26–1.47 (m, 18H, −CH
2
), 1.74–1.84 (m, 2H, −CH
2
2
(
1
3
8
.57 (t, 1H, Py−H, J = 7.8 Hz), 8.88 (d, 2H, Py−H, J = 5.7 Hz). C NMR (75 MHz, CDCl
3
): δ
1
4.25, 26.08, 29.16, 29.50, 29.71, 29.76, 32.04, 68.94, 116.37, 125.42, 129.11, 135.47, 143.98,
1
9
1
46.11, 161.67. F NMR (282 MHz, CDCl
3
): δ −155.16, −155.10. ESI−HRMS (+ve): m/z calcd
34NO : 340.2635 [M ]; found: 340.2608. ESI−HRMS (−ve): m/z calcd for BF ˉ: 87.0035
NO: C, 64.65; H, 8.02; N, 3.28; found: C, 64.56;
+
+
for C23
H
4
[
Mˉ]; found: 87.0041. Anal. calcd for C23
H, 8.02; N, 3.23.
N-(4-Decyloxyphenyl)pyridinium tetrafluoroborate 2–BF
NMR (300 MHz, CDCl ): δ 0.88 (t, 3H, −CH , J = 6.6 Hz), 1.28–1.46 (m, 14H, −CH
m, 2H, −CH ), 4.00 (t, 2H, −OCH , J = 6.3 Hz), 7.08 (d, 2H, Ar−H, J = 9.0 Hz), 7.63 (d, 2H,
Ar−H, J = 9.0 Hz), 8.19 (dd, 2H, Py−H, J = 6.9, 7.2 Hz), 8.58 (t, 1H, Py−H, J = 7.8 Hz), 8.89 (d,
H34BF
4
1
4
(n = 10). Brownish powder; H
3
3
2
), 1.76–1.85
(
2
2
1
3
2
H, Py−H, J = 6.0 Hz). C NMR (75 MHz, CDCl
3
): δ 14.27, 22.83, 26.09, 29.16, 29.47, 29.71,
1
9
3
2.04, 68.97, 116.44, 125.44, 129.13, 135.45, 144.02, 146.06, 161.76. F NMR (282 MHz,
+
+
CDCl
3
): δ −155.00, −155.05. ESI−HRMS (+ve): m/z calcd for C21
ˉ: 87.0035 [Mˉ]; found: 87.0034. Anal. calcd for
NO: C, 63.17; H, 7.57; N, 3.51; found: C, 63.04; H, 7.58; N, 3.47.
N-(4-Tetradecyloxyphenyl)pyridinium tetrafluoroborate 2–BF (n = 14). Brownish powder; H
NMR (300 MHz, CDCl ): δ 0.87 (t, 3H, −CH , J = 6.6 Hz), 1.26–1.46 (m, 22H, −CH ), 1.71–1.82
m, 2H, −CH ), 3.99 (t, 2H, −OCH , J = 6.6 Hz), 7.07 (d, 2H, Ar−H, J = 9.0 Hz), 7.62 (d, 2H,
Ar−H, J = 9.0 Hz), 8.18 (dd, 2H, Py−H, J = 6.9, 7.2 Hz), 8.57 (t, 1H, Py−H, J = 7.8 Hz), 8.88 (d,
H30NO : 312.2322 [M ]; found:
3
12.2302. ESI−HRMS (−ve): m/z calcd for BF
4
C
21
H30BF
4
1
4
3
3
2
(
2
2
1
3
2
H, Py−H) , J = 6.0 Hz. C NMR (75 MHz, CDCl
3
): δ 14.27, 22.83, 26.10, 29.17, 29.52, 29.73,
1
9
2
9.82, 32.06, 68.95, 116.38, 125.42, 129.12, 135.45, 143.98, 146.09, 161.69. F NMR (282 MHz,
24

Page 25 of 34
CrystEngComm
+
+
CDCl
3
): δ −154.85, −154.91. ESI−HRMS (+ve): m/z calcd for C25
H
38NO : 368.2948 [M ]; fVi
o
ew
u
A
n
rt
d
icle Online
:
DOI: 10.1039/C8CE00286J
3
68.2946. ESI−HRMS (−ve): m/z calcd for BF
NO: C, 65.94; H, 8.41; N, 3.08; found: C, 65.95; H, 8.59; N, 3.06.
N-(4-Hexadecyloxyphenyl)pyridinium tetrafluoroborate 2–BF (n = 16). Off white powder; H
NMR (300 MHz, CDCl ): δ 0.87 (t, 3H, −CH , J = 6.9 Hz), 1.32–1.46 (m, 26H, −CH ), 1.76–1.83
m, 2H, −CH ), 4.00 (t, 2H, −OCH , J = 6.3 Hz), 7.08 (d, 2H, Ar−H, J = 9.0 Hz), 7.62 (d, 2H,
Ar−H, J = 9.0 Hz), 8.19 (dd, 2H, Py−H, J = 6.9, 7.2 Hz), 8.58 (t, 1H, Py−H, J = 7.8 Hz), 8.88 (d,
4
ˉ 87.0035 [Mˉ]; found: 87.0038. Anal. calcd for
C
25
H38BF
4
1
4
3
3
2
(
2
2
1
3
2
H, Py−H, J = 6.0 Hz). C NMR (75 MHz, CDCl
3
): δ 14.28, 22.84, 26.11, 29.18, 29.53, 29.85,
1
9
3
2.07, 68.98, 116.44, 125.44, 129.13, 135.45, 144.02, 146.07, 161.76. F NMR (282 MHz,
+
+
CDCl
3
): δ = −154.97, −155.02. ESI−HRMS (+ve): m/z calcd for C23
ˉ: 87.0035 [Mˉ]; found: 87.0038. Anal.
NO: C, 67.08; H, 8.76; N, 2.90; found: C, 67.11; H, 8.81; N, 2.95.
H34NO : 396.3261 [M ];
found: 396.3241. ESI−HRMS (−ve): m/z calcd for BF
4
calcd for C27
H42BF
4
N-(4-Dodecyloxyphenyl)pyridinium trifluoromethanesulfonate 2-OTf (n = 12). White powder,
1
H−NMR (300 MHz, CDCl
.76–1.86 (m, 2H, −CH ), 4.01 (t, 2H, −OCH
d, 2H, Ar−H, J = 9.0 Hz), 8.23 (dd, 2H, Py−H, J = 6.9, 7.5 Hz), 8.59 (t, 1H, Py−H, J = 7.8 Hz),
3
): δ 0.87 (t, 3H, −CH
3
, J = 6.6 Hz), 1.27–1.48 (m, 18H, −CH
2
),
1
2
2
, J = 6.6 Hz), 7.09 (d, 2H, Ar−H, J = 9.3 Hz), 7.66
(
1
3
8
.98 (d, 2H, Py−H, J = 5.4 Hz). C−NMR (75 MHz, CDCl
9.69, 29.73, 32.02, 68.95, 116.41, 120.78 (q, −CF , J = 320.4 Hz), 125.41, 129.14, 135.34,
44.16, 145.90, 161.75. F−NMR (282 MHz, CDCl ): δ −81.53 (s, 3F, −CF ). HR−ESI/MS (+ve):
3
): δ 14.23, 22.79, 26.05, 29.13, 29.47,
2
3
19
1
3
3
+
+
m/z calcd for C23
H
34NO : 340.2635 [M ]; found: 340.2613. ESI−HRMS (−ve): m/z calcd for
−
CF
3
O
3
Sˉ: 148.9526[M ]; found: 148.9524. Anal. calcd. for C24
H
34
F
3
NO
4
S: C, 58.88; H, 7.00; N,
2
.86; found: C, 58.87; H, 7.06; N, 2.82.
N-(4-Dodecyloxyphenyl)pyridinium 1-dodecanesulfonate 2-RSO
NMR (300 MHz, CDCl ): δ 0.85–0.89 (m, 6H, −CH ), 1.24–1.47 (m, 36H, −CH
), 2.78–2.84 (m, 2H, −SO CH ), 4.01 (t, 2H, −OCH , J = 6.6 Hz), 7.09 (d, 2H, Ar−H, J =
.0 Hz), 7.77 (d, 2H, Ar−H, J = 9.0 Hz), 8.37 (dd, 2H, Py−H, J = 6.6, 7.5 Hz), 8.55 (t, 1H, Py−H, J
1
3
(n = 12). White powder; H
3
3
2
), 1.76–1.86 (m,
4
9
H, −CH
2
2
2
2
25

CrystEngComm
Page 26 of 34
1
3
=
7.8 Hz), 9.20 (d, 2H, Py−H, J = 5.4 Hz). C NMR (75 MHz, CDCl
3
): δ 14.26, 22.82, 25.5
V
5
iew Article Online
,
DOI: 10.1039/C8CE00286J
2
1
6.09, 29.18, 29.50, 29.60, 29.79, 32.05, 52.28, 68.96, 116.44, 125.54, 129.42, 135.40, 144.45,
+
+
45.62, 161.71. ESI−HRMS (+ve): m/z calcd for C23
Sˉ: 249.1530 [Mˉ]; found: 249.1519. Anal. calcd for
O: C, 67.16; H, 10.14; N, 2.24; found: C, 66.86; H, 10.10; N, 2.26.
N-(4-Dodecyloxyphenyl)pyridinium thiocyanate 2−SCN (n = 12). Off white powder; H NMR
300 MHz, CDCl ): δ 0.87 (t, 3H, −CH , J = 6.3 Hz), 1.26–1.48 (m, 18H, −CH ), 1.76–1.86 (m,
H, −CH ), 4.02 (t, 2H, −OCH , J = 6.3 Hz), 7.12 (d, 2H, Ar−H, J = 8.7 Hz), 7.77 (d, 2H, Ar−H, J
9.0 Hz), 8.35 (dd, 2H, Py−H, J = 6.3, 6.3 Hz), 8.67 (t, 1H, Py−H, J = 7.2 Hz), 9.09 (d, 2H, Py−H,
H34NO : 340.2635 [M ]; found: 340.2627.
ESI−HRMS (−ve): m/z calcd for C12
S•2H
H
25
O
3
C
35
H59NO
4
2
1
(
3
3
2
2
2
2
=
1
3
J = 5.4 Hz). C NMR (75 MHz, CDCl ): δ 14.26, 22.83, 26.10, 29.18, 29.50, 29.77, 32.05, 69.01,
3
116.50, 125.58, 129.27, 131.64 (s, SCN), 135.39, 144.12, 146.02, 161.74. ESI−HRMS (+ve): m/z
+
+
calcd for C23H34NO : 340.2635 [M ]; found: 340.2616. ESI−HRMS (−ve): m/z calcd for CNSˉ:
5
7.9757 [Mˉ]; found: 57.9766. Anal. calcd (%) for C24
C, 71.92; H, 8.61; N, 6.96.
N-(4-Decyloxyphenyl)pyridinium hexafluorophosphate 2−PF
NMR (300 MHz, DMSO−d ): δ 0.86 (t, 3H, −CH , J = 6.9 Hz), 1.26–1.43 (m, 14H, −CH
.70–1.79 (m, 2H, −CH ), 4.09 (t, 2H, −OCH , J = 6.3 Hz), 7.25 (d, 2H, Ar−H, J = 9.0 Hz), 7.80
d, 2H, Ar−H, J = 9.0 Hz), 8.26 (dd, 2H, Py−H, J = 7.2, 6.9 Hz), 8.73 (t, 1H, Py−H, J = 7.8 Hz),
H
34
N
2
OS: C, 72.32; H, 8.60; N, 7.03; found:
1
6
(n = 10). Brownish powder; H
6
3
2
),
1
2
2
(
1
3
9
.27 (d, 2H, Py−H, J = 5.7 Hz). C NMR (75 MHz, DMSO−d
6
): δ 14.01, 22.14, 25.46, 28.51,
1
9
2
8.75, 29.00, 29.05, 31.33, 68.27, 115.60, 126.06, 128.06, 135.76, 144.79, 145.97, 160.56. F
NMR (282 MHz, DMSO−d ): δ −72.45 (d, P−F, J = 710.4Hz). ESI−HRMS (+ve): m/z calcd for
6
+
+
C
21
H
30NO : 312.2322 [M ]; found: 312.2303. ESI−HRMS (−ve): m/z calcd for F Pˉ: 144.9647
6
[
Mˉ]; found: 144.9645. Anal. calcd for C21
H, 6.60; N, 3.08.
N-(4-Dodecyloxyphenyl)pyridinium hexafluorophosphate 2−PF
NMR (300 MHz, DMSO−d ): δ 0.86 (t, 3H, −CH , J = 6.9Hz), 1.25–1.45 (m, 18H, −CH ),
H
30
F
6
NOP: C, 55.14; H, 6.61; N, 3.06; found: C, 55.10;
1
6
(n = 12). White powder; H
6
3
2
26

Page 27 of 34
CrystEngComm
1
.71–1.80 (m, 2H, −CH
2
), 4.09 (t, 2H, −OCH
2
, J = 6.6 Hz), 7.25 (d, 2H, Ar−H, J = 9.0 Hz),
V
7
ie
.
w Article Online
8
0
DOI: 10.1039/C8CE00286J
(d, 2H, Ar−H, J = 9.0 Hz), 8.26 (dd, 2H, Py−H, J = 6.9, 7.8 Hz), 8.73 (t, 1H, Py−H, J = 9.0 Hz),
1
3
9
.27 (d, 2H, Py−H, J = 6.6 Hz). C NMR (75 MHz, DMSO−d
6
): δ 13.92, 22.07, 25.40, 28.46,
1
9
2
8.69, 28.98, 31.27, 68.24, 115.56, 125.99, 128.01, 135.71, 144.73, 145.92, 160.52. F NMR (282
MHz, DMSO−d
6
): δ −72.44 (d, P−F, J = 710.4Hz). ESI−HRMS (+ve): m/z calcd for C23
Pˉ: 144.9647 [Mˉ]; found:
NOP: C, 56.90; H, 7.06; N, 2.89; found: C, 56.54; H, 7.08; N,
H
34NO+:
+
3
1
2
40.2635 [M ]; found: 340.2616. ESI−HRMS (−ve): m/z calcd for F
6
44.9649. Anal. calcd for C23
.87.
H F
34 6
N-(4-Tetradecyloxyphenyl)pyridinium hexafluorophosphate 2−PF
6
(n = 14). Off white powder;
),
, J = 6.6 Hz), 7.25 (d, 2H, Ar−H, J = 9.0 Hz), 7.80
d, 2H, Ar−H, J = 9.0 Hz), 8.26 (dd, 2H, Py−H, J = 7.2, 7.2 Hz), 8.73 (t, 1H, Py−H, J = 7.8 Hz),
1
H NMR (300 MHz, DMSO−d
6
): δ 0.85 (t, 3H, −CH
3
, J = 6.9Hz), 1.24–1.43(m, 22H, −CH
2
1
.70–1.77 (m, 2H, −CH ), 4.09 (t, 2H, −OCH
2
2
(
1
3
9
.27 (d, 2H, Py−H, J = 5.7 Hz). C NMR (75 MHz, DMSO−d
6
): δ 14.00, 22.14, 25.48, 28.53,
1
9
2
8.77, 29.07, 31.34, 68.27, 115.59, 126.05, 128.07, 135.76, 144.79, 145.98, 160.55. F NMR (282
MHz, DMSO−d
6
): δ −72.44 (d, P−F, J = 710.4 Hz); ESI−HRMS (+ve): m/z calcd for C25
Pˉ: 144.9647 [Mˉ]; found:
NOP: C, 58.47; H, 7.46; N, 2.73; found: C, 58.53; H, 7.56; N,
H
38NO+:
+
3
1
2
68.2948 [M ]; found: 368.2926. ESI−HRMS (−ve): m/z calcd for F
6
44.9651. Anal. calcd for C25
.71.
H F
38 6
N-(4-Hexadecyloxyphenyl)pyridinium hexafluorophosphate 2−PF
6
(n = 16). White powder;
),
, J = 6.3 Hz), 7.26 (d, 2H, Ar−H, J = 9.0 Hz), 7.80
d, 2H, Ar−H, J = 6.9 Hz), 8.27 (dd, 2H, Py−H, J = 6.9, 7.5 Hz), 8.73 (t, 1H, Py−H, J = 7.8 Hz),
1
H NMR (300 MHz, DMSO−d
6
): δ 0.85 (t, 3H, −CH
3
, J = 6.3Hz), 1.24–1.43 (m, 26H, −CH
2
1
.70–1.77 (m, 2H, −CH ), 4.09 (t, 2H, −OCH
2
2
(
1
3
9
.27 (d, 2H, Py−H, J = 5.7 Hz). C NMR (75 MHz, DMSO−d
6
): δ 14.22, 22.35, 25.68, 28.71,
1
9
2
8.94, 29.25, 31.53, 68.52, 115.87, 126.20, 128.33, 135.95, 144.85, 146.21, 160.78. F NMR (282
MHz, DMSO−d
6
): δ −72.44 (d, P−F, J = 710.1 Hz). ESI−HRMS (+ve): m/z calcd for C27
H
42NO+:
+
3
96.3261 [M ]; found: 396.3239. ESI−HRMS (−ve): m/z calcd for F
6
Pˉ: 144.9647 [Mˉ]; found:
27

CrystEngComm
Page 28 of 34
1
2
44.9642. Anal. calcd for C27
.59.
H
42
F
6
NOP: C, 59.88; H, 7.82; N, 2.59; found: C, 59.90; H, 7.9
V
1
ie
;
w
N
Article Online
,
DOI: 10.1039/C8CE00286J
N-(4-Dodecyloxyphenyl)pyridinium bis(trifluoromethanesulfonic)imide 2-NTf
2
(n = 12). Off
1
white powder; H NMR (300 MHz, CDCl
3
): δ 0.88 (t, 3H, −CH
), 4.03 (t, 2H, −OCH , J = 6.3 Hz), 7.11 (d, 2H, Ar−H, J = 9.0 Hz),
.60 (d, 2H, Ar−H, J = 9.0 Hz), 8.20 (dd, 2H, Py−H, J = 6.9, 7.5 Hz), 8.59 (t, 1H, Py−H, J = 7.8
3
, J = 6.6 Hz), 1.27–1.49 (m, 18H,
−
CH
2
), 1.77–1.87 (m, 2H, −CH
2
2
7
1
3
Hz), 8.87 (d, 2H, Py−H, J = 5.7 Hz). C NMR (75 MHz, CDCl
3
): δ 14.24, 22.81, 26.06, 29.13,
, J = 321.3 Hz), 125.34, 129.04, 135.25,
44.02, 145.91, 161.95. F NMR (282 MHz, CDCl ): δ −82.02 (s, −CF , 6F). ESI−HRMS (+ve):
34NO : 340.2635 [M ]; found: 340.2623. ESI−HRMS (−ve): m/z calcd for
: C, 48.38; H, 5.52;
2
9.48, 29.77, 32.04, 69.01, 116.50, 119.88 (q, −CF
3
19
1
3
3
+
+
m/z calcd for C23
H
C
2
F
6
4
NO S
2
ˉ: 279.9178 [Mˉ]; found: 279.9178. Anal. calcd for C25
H
34
F
6
N
2 5 2
O S
N, 4.51; found: C, 48.32; H, 5.53; N, 4.52.
N-(4-Tetradecyloxyphenyl)pyridinium bis(trifluoromethanesulfonic)imide 2-NTf (n = 14).
2
1
Off white powder; H NMR (300 MHz, CDCl
3
): δ 0.87 (t, 3H, −CH
3
, J = 6.9 Hz), 1.32–1.47 (m,
2
9
=
2H, −CH
2
), 1.77–1.86 (m, 2H, −CH
2
), 4.03 (t, 2H, −OCH , J = 6.6 Hz), 7.11 (d, 2H, Ar−H, J =
2
.0 Hz), 7.60 (d, 2H, Ar−H, J = 8.7 Hz), 8.19 (dd, 2H, Py−H, J = 7.2, 7.2 Hz), 8.58 (t, 1H, Py−H, J
1
3
7.8 Hz), 8.87 (d, 2H, Py−H, J = 6.0 Hz). C NMR (75 MHz, CDCl
3
): δ 14.25, 22.81, 26.07,
, J = 319.2 Hz), 125.34,
): δ −82.06 (s, −CF , 6F).
38NO : 368.2948 [M ]; found: 368.2927. ESI−HRMS (−ve):
: C,
2
9.14, 29.49, 29.70, 29.74, 29.80, 32.05, 69.02, 116.50, 119.87 (q, −CF
3
1
9
1
29.04, 135.24, 144.01, 145.91, 161.95. F NMR (282 MHz, CDCl
3
3
+
+
ESI−HRMS (+ve): m/z calcd for C25
H
m/z calcd for C
2
F
6
NO
4
S
2
ˉ: 279.9178 [Mˉ]; found: 279.9175. Anal. calcd for C27
H
38
F
6
N
2
O S
5 2
4
9.99; H, 5.90; N, 4.32; found: C, 49.89; H, 5.91; N, 4.32.
N-(4-Hexadecyloxyphenyl)pyridinium bis(trifluoromethanesulfonic)imide 2-NTf (n = 16).
2
1
White powder; H NMR (300 MHz, CDCl
3
): δ 0.87 (t, 3H, −CH
), 4.03 (t, 2H, −OCH , J = 6.6 Hz), 7.11 (d, 2H, Ar−H, J = 9.3 Hz),
.60 (d, 2H, Ar−H, J = 9.0 Hz), 8.20 (dd, 2H, Py−H, J = 6.9, 7.2 Hz), 8.59 (t, 1H, Py−H, J = 8.1
3
, J = 6.9 Hz), 1.32–1.47 (m, 26H,
−
CH
2
), 1.77–1.87 (m, 2H, −CH
2
2
7
28

Page 29 of 34
CrystEngComm
1
3
Hz), 8.87 (d, 2H, Py−H, J = 5.7 Hz). C NMR (75 MHz, CDCl
3
): δ 14.26, 22.83, 26.08, 29.1iew5,Article Online
V
DOI: 10.1039/C8CE00286J
2
1
9.51, 29.72, 29.76, 29.84, 32.07, 69.06, 116.54, 119.89 (q, −CF , J = 319.4 Hz), 125.36, 129.07,
3
1
9
35.24, 144.05, 145.94, 162.00. F NMR (282 MHz, CDCl
3
): δ −82.04 (s, −CF
3
, 6F). ESI−HRMS
+
+
(+ve): m/z calcd for C27
H
42NO : 396.3261 [M ]; found: 396.3246. ESI−HRMS (−ve): m/z calcd
for C
2
F
6
NO
4
S
2
ˉ: 279.9178 [Mˉ]; found: 279.9173. Anal. calcd for C27 : C, 51.47; H,
H
38
F
6
N
2
O
5 2
S
6
.26; N, 4.14; found: C, 51.27; H, 6.21; N, 4.12.
Acknowledgements
We thank the Ministry of Science and Technology, Taiwan, ROC (MOST 106−2113−M−008−012)
in generous support of this work. Also we deeply appreciated Prof. Hwo−Shuenn Sheu for
performing powder XRD experiments at the National Synchrotron Radiation Research Center.
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