2
S.-H. Hsiao et al. / Reactive and Functional Polymers xxx (2016) xxx–xxx
synthesize
a
new diamine monomer, 4,4′-diamino-4″-(1-
ppm): 143.5 (C4), 141.9 (C7), 118.6 (C6), 114.7 (C5), 52.1 (C3), 25.8 (C2),
23.8 (C1).
piperidinyl)triphenylamine, and its derived aramids containing the
electroactive TPA unit with 1-piperidinyl substituent as an auxiliary
donor. We anticipated that incorporating (1-piperidinyl)TPA unit into
the aramid backbone could improve the solubility, electrochemical sta-
bility, and electrochromic performance.
2. Experimental section
2.2.3. 4,4′-Dinitro-4″-(1-piperidinyl)triphenylamine (3)
In a 250 mL round-bottom flask equipped with a stirring bar, a mix-
ture of 12.0 g (0.068 mol) of amino compound 2, 19.2 g (0.136 mol) of
4-fluoronitrobenzene, and 20.7 g (0.136 mol) of cesium fluoride (CsF)
in 100 mL of dimethyl sulfoxide (DMSO) was heated with stirring at
120 °C for 20 h. After cooling, the mixture was poured into 400 mL
mixed solution of ethanol/water (1:1), and the dark red precipitate
was collected by filtration. Recrystallization from DMF/H2O yielded
18.5 g of the desired dinitro compound (3) as red crystals in 65% yield.
[mp: 168–171 °C, measured by differential scanning calorimetry (DSC)
at a scan rate of 10 °C/min]. IR (KBr): 1579, 1340 cm−1 (\\NO2 str.).
1H NMR (500 MHz, DMSO-d6, δ, ppm): 8.15 (d, J = 9.2 Hz, 4H, Hg),
7.17 (d, J = 9.2 Hz, 4H, Hf), 7.07 (d, J = 9.0 Hz, 2H, He), 7.02 (d, J =
9.0 Hz, 2H, Hd), 3.20 (t, J = 5.6 Hz, 4H, Hc), 1.62 (m, 4H, Hb), 1.55 (m,
2H, Ha). 13C NMR (125 MHz, DMSO-d6, δ, ppm): 151.7 (C8), 150.3 (C4),
141.5 (C11), 134.1 (C7), 128.4 (C6), 125.4 (C10), 121.6 (C9), 116.7 (C5),
48.8 (C3), 25.1 (C2), 23.7 (C1).
2.1. Materials
Piperidine (Tedia), 4-fluoronitrobenzene (Acros), potassium car-
bonate (K2CO3) (Showa), cesium fluoride (CsF) (Acros), dimethyl sulf-
oxide (DMSO), 10% palladium on charcoal (Pd/C) (Fluka), hydrazine
monohydrate (TCI) were used as received. N,N-Dimethylacetamide
(DMAc) (Tedia), N,N-dimethylformamide (DMF) (Tedia), triphenyl
phosphite (TPP) (Acros), pyridine (Py) (Wako) and N-methyl-2-
pyrrolidone (NMP) (Tedia) were dried over calcium hydride for
24 h, distilled under reduced pressure, and stored over 4 Å molecular
sieves in a sealed bottle. The commercially available aromatic dicar-
boxylic acids including terephthalic acid (5a) (Wako), isophthalic
acid (5b) (Wako), 4,4′-biphenydicarboxylic acid (5c) (TCI), 4,4′-
dicarboxydiphenyl ether (5d) (TCI), bis(4-carboxyphenyl) sulfone
(5e)
carboxyphenyl)hexafluoropropane
naphthalenedicarboxylic acid
(New
Japan
Chemicals
(5f)
(Wako),
Co.),
(TCI),
and
2,2-bis(4-
1,4-
2,6-
(5g)
naphthalenedicarboxylic acid (5h) (TCI) were used as received.
Commercially obtained calcium chloride (CaCl2) (Wako) was dried
under vacuum at 180 °C for 8 h prior to use. Tetrabutylammonium
perchlorate (TBAP) (Acros) was dried in vacuo before use. All other
reagents were used as received from commercial sources.
2.2. Synthesis of (1-piperidinyl)TPA diamine monomer
2.2.1. 1-(4-Nitrophenyl)piperidine (1)
2.2.4. 4,4′-Diamino-4″-(1-piperidinyl)triphenylamine (4)
In a 250 mL round-bottom flask equipped with a stirring bar, a mix-
ture of 12.8 g (0.15 mol) of piperidine, 21.2 g (0.15 mol) of 4-
fluoronitrobenzene, and 20.7 g (0.15 mol) of potassium carbonate
(K2CO3) in 100 mL of dimethyl sulfoxide (DMSO) was heated with stir-
ring at 120 °C for 20 h. After cooling, the mixture was poured into
400 mL mixed solution of ethanol/water (1:1). The yellow crystals
were collected by filtration with a yield of 30.0 g (97%) and a melting
point of 100–102 °C, measured by differential scanning calorimetry
(DSC) at a scan rate of 10 °C/min. IR (KBr):1577, 1329 cm−1 (\\NO2
str.). 1H NMR (500 MHz, DMSO-d6, δ, ppm): 8.02 (d, J = 9.5 Hz, 2H,
He), 6.98 (d, J = 9.5 Hz, 2H, Hd), 3.49 (t, J = 5.7 Hz, 4H, Hc), 1.63 (m,
2H, Ha), 1.57 (m, 4H, Hb). 13C NMR (125 MHz, DMSO-d6, δ, ppm):
154.5 (C4), 135.9 (C7), 125.8 (C6) 112.2 (C5), 47.5 (C3), 24.8 (C2), 23.8
(C1).
In a 500 mL round-bottom flask, 10 g (0.024 mol) of dinitro com-
pound 3, 0.15 g of 10 wt% Pd/C, 8 mL hydrazine monohydrate and
100 mL of ethanol was stirred at a reflux temperature for 12 h. The so-
lution was filtered hot to remove Pd/C, and the filtrate was then cooled
to precipitate white needles. The product (4) was collected by filtration
and dried in vacuo at 70 °C to give 5.5 g (yield 73%) of diamine 4 as
white needles. [mp: 172–174 °C, measured by differential scanning cal-
orimetry (DSC) at a scan rate of 10 °C/min]. IR (KBr): 3338, 3291 cm−1
(\\NH2 str.). ANAL. Calculated for C23H26N4 (358.48): C, 77.06%; H,
7.31%; N, 15.63%. Found: C, 76.86%; H, 7.26%; N, 15.63%. 1H NMR
(500 MHz, DMSO-d6, δ, ppm): 6.74 (d, J = 9.1 Hz, 2H, Hd), 6.68 (d,
J = 8.6 Hz, 4H, Hf), 6.65 (d, J = 9.0 Hz, 2H, He), 6.49 (d, J = 8.7 Hz,
4H, Hg), 4.79 (s, 4H,\\NH2), 2.95 (t, J = 5.4 Hz, 4H, Hc), 1.59 (m, 4H,
Hb), 1.47 (m, 2H, Ha). 13C NMR (125 MHz, DMSO-d6, δ, ppm): 145.5
(C11), 144.02 (C8), 141.8 (C4), 137.5 (C7), 125.4 (C9), 120.8 (C6), 117.3
(C5), 114.7 (C10), 50.7 (C3), 25.5 (C2), 23.7 (C1).
2.2.2. 4-(1-Piperidinyl)aniline (2)
In a 500 mL round-bottom flask, 28.3 g (0.14 mol) of nitro com-
pound 1, 0.2 g of 10 wt% Pd/C, 20 mL hydrazine monohydrate and
180 mL of ethanol was stirred at a reflux temperature for 10 h. The so-
lution was filtered hot to remove Pd/C, and the filtrate was evaporated
under reduced pressure to dryness. A deep purplish red liquid was ob-
tained. The product (2) was used for the next step without further puri-
fication. The yield was 18.1 g (75%). IR (KBr): 3429, 3346 cm−1 (\\NH2
str.). 1H NMR (500 MHz, DMSO-d6, δ, ppm): 6.66 (d, J = 8.8 Hz, 2H, He),
6.48 (d, J = 8.8 Hz, 2H, Hd), 4.49 (s, 2H,\\NH2), 2.84 (t, J = 5.4 Hz, 4H,
Hc), 1.59 (m, 4H, Hb), 1.45 (m, 2H, Ha). 13C NMR (125 MHz, DMSO-d6, δ,
Please cite this article as: S.-H. Hsiao, et al., Triphenylamine-based redox-active aramids with 1-piperidinyl substituent as an auxiliary donor: