T. Zhang, et al.
DyesandPigments171(2019)107692
EW abilities of substituent groups may determine the photophysical
properties of the compounds in solution by regulating molecular LUMO
energy levels. The crystals of the compounds emitted fluorescence that
ranged in color from blue to orange-red, and the results of their π-
packing models differed on the basis of their strong EW groups. MFC
measurements suggest that all four compounds exhibited reversible
fluorescence conversion after grinding and solvent fuming. The com-
pounds exhibited different fluorescence recovery times under thermal
annealing. PVBM and PVBA could spontaneously recover their fluor-
escence within 1 h at room temperature. PVBMA and NSP may retain
mechanically written information for long durations. The obtained re-
sults indicate that molecular MFC features can be easily regulated
through mild substituent adjustment.
6.97 (d, J = 8.7 Hz, 1H), 6.94–6.79 (m, 5H), 3.94 (s, 5H), 1.42 (t,
J = 6.9 Hz, 3H). 13C NMR (101 MHz, CDCl3) δ 189.74, 189.70, 161.09,
144.49, 144.25, 133.68, 131.67, 130.49, 127.37, 127.30, 127.07,
125.86, 125.81, 125.24, 124.87, 124.75, 124.60, 123.83, 122.44,
115.06, 112.01, 55.87, 55.83, 41.96, 12.97. Elemental Analysis: C,
74.39; H, 5.46; N, 3.61; found: C, 74.45; H, 5.66; N, 3.57.
4.1.2. (E)-methyl
(PVBM)
4-(2-(10-ethyl-10H-phenothiazin-3-yl)vinyl)benzoate
PVBM was obtained through the same procedure as that of PVBMA.
Yield: 88%. m.p: 133–135 °C. 1H NMR (400 MHz, CDCl3) δ 8.04–7.95
(m, 2H), 7.56–7.45 (m, 2H), 7.30–7.22 (m, 2H), 7.18–7.10 (m, 2H),
7.06 (d, J = 16.3 Hz, 1H), 6.95 (d, J = 16.8 Hz, 1H), 6.90 (d,
J = 7.5 Hz, 1H), 6.86 (d, J = 8.1 Hz, 1H), 6.82 (d, J = 8.4 Hz, 1H), 3.91
(s, 5H), 1.41 (t, J = 6.9 Hz, 3H). 13C NMR (101 MHz, CDCl3) δ 166.91,
144.78, 144.32, 142.02, 131.24, 130.03, 129.97, 128.60, 127.38,
127.35, 126.29, 126.10, 125.81, 125.11, 124.64, 123.71, 122.57,
115.12, 115.00, 52.06, 52.01, 41.99, 12.98. Elemental Analysis: C,
74.39; H, 5.46; N, 3.61; found: C, 74.40; H, 5.62; N, 3.54.
4. Experiment sections
4.1. Measurements and instruments
1H and 13C NMR spectrum was recorded using a Bruker Avance
400 MHz spectrometer at 400 MHz and 100 MHz in DMSO‑d6. FT-IR
spectra were recorded using a Nicolet-360 FT-IR spectrometer by
casting samples into a KBr crystal. UV–Vis spectra were obtained on a
Mapada UV-1800pc spectrophotometer. Fluorescence emission spectra
were obtained on a FL-3 fluorescence spectrophotometer. C, H, and N
elemental analyses were performed on a PerkinElmer 240C elemental
analyzer. XRD patterns were obtained on a Bruker D8 Advance X-ray
diffraction instrument equipped with graphite-mono-chromatized
CuKα radiation (λ = 1.5418 Å), by employing a scanning rate of
0.0261° s−1 in the 2θ range from 5° to 30°. Heating recovery of ground
solids was employed using a temperature-controlled heating board.
Cyclic voltammetry was employed using a three-electrode cell and an
electrochemistry work station (CHI 604) at room temperature at a scan
rate of 50 mV s−1. The working electrode was a glass carbon disc, the
auxiliary electrode was a Pt wire, and Ag/Ag+ was used as reference
electrode. Tetrabutylammonium tetrafluoroborate (TBABF4, 0.1 M) was
used as the supporting electrolyte in dry CH2Cl2 and the ferrocenium/
ferrocene (Fc/Fc+) redox couple was used as an internal potential re-
ference. Geometrical optimization was performed by density functional
theory (DFT) calculations at B3LYP/6-31G(d) level with the Gaussian
09 W program package. Electronic transition data of PVBMA, PVBM,
and PVBA were obtained by the TD/DFT-mpw1pw91/6-31G(d) calcu-
lation based on the configuration at ground state. Electronic transition
of NSP is from TD/DFT-b3lyp/6-311G(d) calculation.
4.1.3. (E)-4-(2-(10-ethyl-10H-phenothiazin-3-yl)vinyl)benzaldehyde
(PVBA)
PVBA was obtained through the same procedure as that of PVBMA.
Yield: 91%. m.p: 165–166 °C. 1H NMR (400 MHz, CDCl3) δ 9.98 (s, 1H),
7.91–7.78 (m, 2H), 7.61 (d, J = 8.2 Hz, 2H), 7.37–7.27 (m, 2H),
7.20–7.08 (m, 3H), 7.06–6.79 (m, 4H), 3.95 (s, 2H), 1.44 (t, J = 6.9 Hz,
3H). 13C NMR (101 MHz, CDCl3) δ 191.54, 143.64, 135.10, 131.11,
131.04, 131.03, 130.24, 127.38, 125.54, 125.19, 124.71, 123.66,
122.66, 115.16, 115.01, 42.04, 13.05. Elemental Analysis: C, 77.28; H,
5.36; N, 3.92; found: C, 77.21; H, 5.46; N, 3.99.
4.1.4. (E)-10-ethyl-3-(4-nitrostyryl)-10H-phenothiazine (NSP)
PVBA was obtained through the same procedure as that of PVBMA.
Yield: 91%. m.p: 165–166 °C. 1H NMR (400 MHz, CDCl3) δ 8.16 (d,
J = 8.9 Hz, 2H), 7.54 (d, J = 8.9 Hz, 2H), 7.28 (s, 1H), 7.27 (dd,
J = 8.2, 2.4 Hz, 1H), 7.15 (td, J = 8.0, 1.6 Hz, 1H), 7.11 (dd, J = 8.0,
1.6 Hz, 1H), 7.09 (d, J = 16.8, 1H), 6.94 (d, J = 16.8, 1H), 6.92 (t,
J = 8.0 Hz, 1H), 6.88 (d, J = 8.0 Hz, 1H), 6.84 (d, J = 8.2 Hz, 1H), 3.92
(q, J = 7.0 Hz, 2H), 1.42 (t, J = 6.9 Hz, 3H). 13C NMR (101 MHz,
CDCl3) δ 146.47, 145.27, 144.07, 132.05, 130.64, 130.62, 127.45,
127.39, 126.70, 126.56, 125.28, 124.72, 124.69, 124.43, 124.14,
123.52, 123.49, 122.76, 115.23, 115.02, 42.17, 42.12, 12.94, 12.92.
Elemental Analysis: C, 70.57; H, 4.85; N, 7.48; found: C, 70.67; H, 4.81;
N, 7.41.
Single crystals of two compounds were obtained by slowing solvent
evaporation (CH2Cl2 and n-hexane mixture) and selected for X-ray
diffraction analysis on in a Rigaku RAXIS-RAPID diffractometer using
graphite-monochromated Mo-Kα radiation (λ = 0.71073 Å). The crys-
tals were kept at room temperature during data collection. The struc-
tures were solved by the direct methods and refined on F2 by full-
matrix least-square using the SHELXTL-97 program. The C, N, O and H
atoms were easily placed from the subsequent Fourier-difference maps
and refined anisotropically. CCDC 1906762 and 1906792 contain the
supplementary crystallographic data for PVBM and NSP.
Acknowledgements
This work was supported by the Scientific Research Foundation of
Tianjin Normal University (Grant No. 5RL151), the Foundation of
Development Program of Future Expert in Tianjin Normal University
(WLQR201804) and the Science &Technology Development Fund of
Tianjin Education Commission for Higher Education (2018ZD12).
Appendix A. Supplementary data
4.1.1. (E)-5-(2-(10-ethyl-10H-phenothiazin-3-yl)vinyl)-2-
methoxybenzaldehyde (PVMBA)
Supplementary data to this article can be found online at https://
10-ethyl-3-vinyl-10H-phenothiazine (1.5 g, 5.92 mmol), 5-bromo-2-
methoxybenzaldehyde (1.27 g, 5.92 mmol), K2CO3 (1.8 g, 13 mmol),
and tetrabutylammonium bromide (4.0 g, 12.4 mmol) were dispersed in
dry DMF (20 mL) and then 1.0 mg PdCl2 was added. The mixture was
heated at 120 °C under N2 for 12 h, and poured into 200 mL water. The
crude product was obtained by suction. Product was achieved by
column chromatography on silica gel using CH2Cl2/petroleum ether
(V/V = 1:2) as eluent. Yield: 89%. m.p: 177–178 °C. 1H NMR
(400 MHz, CDCl3) δ 10.47 (s, 1H), 7.95 (d, J = 2.4 Hz, 1H), 7.63 (dd,
J = 8.7, 2.4 Hz, 1H), 7.23 (dd, J = 8.3, 2.1 Hz, 1H), 7.18–7.09 (m, 2H),
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