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under N2 atmosphere. After K2CO3 was removed by suction
filtration, dimethylformamide was evaporated and the resi-
due was dried in a vacuum oven at 80 °C for 12 h. The resid-
ual solid was purified by chromatography with silica gel
Crystal growth
Single PMQ-T and POQ-T crystals were grown by solution
growth methods in methanol (HPLC grade, 99.9% purity with
a water content of 0.05%).
PMQ-T. Single PMQ-T crystals were grown by a slow
cooling method in methanol. The PMQ-T solution saturated
at 40 °C in methanol was filtered and cooled at a cooling rate
of 1 °C per day. The first nucleate was observed at 27 °C.
Needle-like single crystals were obtained at 19 °C.
POQ-T. Single POQ-T crystals were grown by a slow evapo-
ration method in methanol solution. The POQ-T solution sat-
urated at 40 °C in methanol (20 ml) was filtered and placed
in an oven at 40 °C. The evaporation rate of methanol was
about 3 ml per day. When about 5 ml of the solution
remained, hexagonal-shaped single crystals were filtered out.
1
using ethyl acetate as the eluent. Yield = 61%. H NMR (400
MHz, DMSO-d6, δ): 9.68 (s, 1H, CHO), 7.68 (d, 2H, J = 8.8 Hz,
C6H4), 7.02 (d, 2H, J = 8.8 Hz, C6H4), 4.75 (s, 1H, OH), 3.77 (t,
2H, J = 25.6 Hz, C5H9N), 3.71 (m, 1H, C5H9N), 3.12 (t, 2H, J =
26.4 Hz, C5H9N), 1.79 (m, 2H, C5H9N), 1.40 (m, 2H, C5H9N).
Elemental analysis for C12H15NO2: calcd. C 70.22, H 7.37, N
6.82 found: C 70.21, H 7.40, N 6.80.
2-(4-(4-(Hydroxymethyl)piperidin-1-yl)styryl)-1-methyl-
quinolinium 4-methylbenzenesulfonate (PMQ-T). 1,2-
Dimethylquinolinium 4-methylbenzenesulfonate (7.06 g, 0.021
mol) and 4-(4-(hydroxymethyl)piperidin-1-yl)benzaldehyde (4.7
g, 0.021 mol) were dissolved in methanol (300 ml). Piperidine
(0.31 ml, 4.29 mmol) was added into the reaction solution
and stirred at 70 °C for 19 h. After cooling to room tempera-
ture, the crystalline powder was filtered. The final product
was obtained by recrystallization in methanol and dried in a
vacuum oven at 75 °C for 12 h. Yield = 29%. 1H NMR (400
MHz, DMSO-d6, δ): 8.84 (d, 1H, J = 8.8 Hz, C5H2N), 8.51 (d,
1H, J = 8.8 Hz, C6H4), 8.44 (d, 1H, J = 8.8 Hz, C6H4), 8.25 (d,
1H, J = 7.2 Hz, C5H2N), 8.22 (d, 1H, J = 15.2 Hz, CH), 8.09 (t,
1H, J = 15.6 Hz, C6H4), 7.86 (t, 1H, J = 15.6 Hz, C6H4), 7.84 (d,
2H, J = 9.2 Hz, C6H4), 7.59 (d, 1H, J = 15.2 Hz, CH), 7.46 (d,
Crystal structure analysis
For single-crystal structure X-ray analysis, PMQ-T single crys-
tals grown in methanol by a slow cooling method are used.
C31H34N2O4S, Mr = 530.66, monoclinic, space group P21, a =
6.4400(4) Å, b = 16.3764(10) Å, c = 12.5711(10) Å, β =
93.626(2)°, V = 1323.14(15)Å3, Z = 2, T = 150.0(5) K, μ(MoKα) =
0.163 mm−1. 5961 reflections were collected in the θ range
3.0°–27.5° using ω scans on a Rigaku R-axis Rapid S diffrac-
tometer. The structure was solved and refined against F2
using SHELXL-2014:34 346 variables, wR2 = 0.162, R1 = 0.059
(Fo2 > 2σ(Fo2)), GOF = 1.122, Flack absolute structure param-
eter x = −0.04(7), and max/min residual electron density
0.461/−0.540 e Å−3. CCDC 1435918.
−
2H, J = 8 Hz, C6H4), 7.10 (d, 2H, J = 7.6 Hz, C6H4SO3 ), 7.06
−
(d, 2H, J = 9.2 Hz, C6H4SO3 ), 4.51 (s, 1H, OH), 4.46 (s, 3H,
NCH3), 4.04 (d, 2H, J = 13.2 Hz, CH2OH), 3.29 (t, 2H, J = 11.6
Hz, C5H9N), 2.91 (t, 2H, J = 23.6 Hz, C5H9N), 2.28 (s, 3H,
CH3), 1.76 (m, 2H, C5H9N), 1.66 (m, 1H, C5H9N), 1.21 (m, 2H,
C5H9N). Elemental analysis for C31H34N2O4S: calcd. C 70.16,
H 6.46, N 5.28, S 6.04; found: C 70.04, H 6.47, N 5.25, S 5.96.
Elemental analysis for C31H34N2O4S: calcd. C 70.16, H 6.46, N
5.28, S 6.04; found: C 70.04, H 6.47, N 5.25, S 5.96.
Hirshfeld surface analysis
In order to investigate the supramolecular interactions of
PMQ-T crystals, we have performed Hirshfeld surface
analysis35–37 using the CrystalExplorer program.38 Since an
ionic PMQ-T crystal consists of two ions, i.e., PMQ cation and
T (4-methylbenzenesulfonate) anion, Hirshfeld surface analy-
sis of both HMQ and T ions together as well as of the HMQ
cation alone has been performed. In the Hirshfeld surface of
normalized contact distance dnorm, which is related with
intermolecular interactions, the red color represents a con-
tact distance shorter than the van der Waals radius, while the
blue color represents a longer contact distance than the van
der Waals radius.35–37 The 2D Hirshfeld surface fingerprint
plots are constructed from di and de, which are distances
from a point on the surface to the nearest inside and outside
atoms, respectively.35–37
2-(4-(4-Hydroxypiperidin-1-yl)styryl)-1-methylquinolinium
4-methylbenzenesulfonate (POQ-T). 1,2-Dimethylquinolinium
4-methylbenzenesulfonate (8.02 g, 0.024 mol) and
4-(4-hydroxypiperidin-1-yl)benzaldehyde (5 g, 0.024 mol) were
dissolved in methanol (300 ml). Piperidine (0.34 ml, 4.87 mmol)
was added into the reaction solution and stirred at 70 °C for 27
h. After cooling to room temperature, the crystalline powder
was filtered. The final product was obtained by recrystallization
in methanol and dried in a vacuum oven at 75 °C for 12 h.
1
Yield = 26%. H NMR (400 MHz, DMSO-d6, δ): 8.84 (d, 1H, J =
8.8 Hz, C5H2N), 8.51 (d, 1H, J = 9.2 Hz, C6H4), 8.45 (d, 1H, J =
8.8 Hz, C6H4), 8.25 (d, 1H, J = 7.2 Hz, C5H2N), 8.22 (d, 1H, J =
15.6 Hz, CH), 8.10 (t, 1H, J = 17.2 Hz, C6H4), 7.86 (t, 1H, J =
15.2 Hz, C6H4), 7.84 (d, 2H, J = 9.2 Hz, C6H4), 7.60 (d, 1H, J =
15.2 Hz, CH), 7.46 (d, 2H, J = 8.4 Hz, C6H4), 7.10 (d, 2H, J = 8.0
Results and discussion
Multi-functional supramolecular building blocks
−
−
Hz, C6H4SO3 ), 7.06 (d, 2H, J = 9.2 Hz, C6H4SO3 ), 4.77 (s, 1H,
OH), 4.46 (s, 3H, NCH3), 3.80 (t, 2H, J = 18.4 Hz, C5H9N), 3.75
(m, 1H, C5H9N), 3.15 (t, 2H, J = 20.4 Hz, C5H9N), 2.28 (s, 3H,
CH3), 1.83 (m, 2H, C5H9N), 1.43 (m, 2H, C5H9N). Elemental
analysis for C30H32N2O4S: calcd. C 69.74, H 6.24, N 5.42, S 6.21;
found: C 69.69, H 6.26, N 5.41, S 6.17.
Fig. 1 shows the chemical structure of the investigated ionic
π-conjugated molecules introducing multi-functional electron-
donating supramolecular building blocks. PMQ-T (2-(4-(4-
(hydroxymethyl)piperidin-1-yl)styryl)-1-methylquinolinium
4-methylbenzenesulfonate) and POQ-T (2-(4-(4-hydroxy-
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