brine and deionized water. Then the organic phase was dried
over MgSO4 and concentrated by rotary evaporation, the residue
was purified via flash chromatography on silica gel using CH2Cl2
[M + H]+, 443.55. Found: 443.30. [M ꢀ H]ꢀ, 441.55. Found:
441.50.
1
as the eluent to yield yellow powder 2. Yield: 57.2%. H NMR
Synthesis of (E)-4-(2-(ethyl(4-((4-nitrophenyl)diazenyl) phenyl)
amino)ethoxy)-4-oxobutanoic acid (4). A mixture of chromo-
phore E1 (0.628 g, 2 mmol), succinic anhydride (0.24 g, 2.4
mmol), 4-dimethylaminopyridine (DMAP) (0.24 g, 2.4 mmol),
pyridine (0.3 mL) and anhydrous CH2Cl2 was stirred at room
temperature overnight. The resulting solution was diluted with
CH2Cl2 and washed with brine and deionized water. The organic
layer was dried over MgSO4, and the solvent was evaporated
under reduced pressure. The residue was purified by column
chromatography on silica gel using a mixture of CH2Cl2/ethyl
acetate (v : v ¼ 25 : 1) as the eluent and compound 4 was gained
(500 MHz, CDCl3, d (ppm)): 4.49 (s, 2H, OCH2), 5.24 (s, 2H,
NH2), 6.66–6.68 (d, 1H, ArH), 7.86–7.88 (d, 2H, ArH). MS
(ESI): exact mass calcd for C13H7F5N2O3 [M + Na]+, 357.20.
Found: 357.00.
Synthesis
of
2-((2-ethylhexyl)oxy)-4-nitroaniline
(3).
Compound 3 was synthesized using a similar procedure to that
1
for compound 2 as orange oil. Yield: 63.34%. H NMR (500
MHz, CDCl3, d (ppm)): 0.87–0.93 (m, 6H, CH2CH3), 1.29–1.31
(m, 4H, CH(CH2)2), 1.38–1.49 (m, 4H, CH2CH3), 1.74–1.76
(t, 1H, CH(CH2)2), 3.91–3.93 (m, 2H, OCH2), 4.74 (s, 2H, NH2),
6.62–6.64 (d, 1H, ArH), 7.61–7.62 (d, 1H, ArH), 7.75–7.77
(m, 1H, ArH). MS (ESI): exact mass calcd for C14H22N2O3 [M +
H]+, 267.34. Found: 267.00. [M ꢀ H]ꢀ, 265.34. Found: 265.10.
1
as red powder. Yield: 68.11%. H NMR (500 MHz, DMSO-d6,
d
(ppm)): 1.15–1.18 (t, 3H, CH3), 2.36–2.46 (m, 4H,
(CH2)2COOH), 3.54–3.55 (d, 2H, NCH2), 3.70–3.72 (t, 2H,
NCH2CH2), 4.23–4.25 (t, 2H, NCH2CH2), 6.92–6.93 (d, 2H,
ArH), 7.84–7.86 (d, 2H, ArH), 7.93–7.95 (d, 2H, ArH), 8.36–8.37
(d, 2H, ArH).
Synthesis of (E)-2-(ethyl(4-((4-nitrophenyl)diazenyl)phenyl)
amino)ethanol (E1). The chromophore E1 was prepared as
reported previously.34 Compound 4-nitroaniline (2.76 g,
20 mmol) was dissolved in a solution of 35% hydrochloric acid
and the mixture was stirred in an ice bath at 0–5 ꢁC. Subse-
quently, a water solution of sodium nitrite (1.38 g, 20 mmol) was
added slowly and the resulting solution was stirred in the ice bath
for 30 min, a solution of 2-(ethyl(phenyl)amino)ethanol (3.96 g,
24 mmol) in distilled ethanol was added dropwise and stirred for
1 h at 5 ꢁC. After pH of the resulting solution was adjusted to 7.0
with potassium carbonate, the reaction was stirred for another 30
min. The red solution was diluted with CH2Cl2 and washed with
brine and deionized water. The crude product was purified by
recrystallization. E1 was obtained as red powder. Yield: 72.7%.
Synthesis of (E)-4-(2-(ethyl(4-((4-nitro-2-((perfluorophenyl)
methoxy)phenyl)diazenyl)phenyl)amino)ethoxy)-4-oxobutanoic
acid (5). Compound 5 was synthesized using a similar procedure
to that for 4 as red powder. Yield: 80.33%. 1H NMR (500 MHz,
CDCl3, d (ppm)): 1.24–1.27 (t, 3H, CH3), 2.64–2.68 (m, 4H,
(CH2)2COOH), 3.53–3.54 (d, 2H, NCH2), 3.69 (s, 2H,
NCH2CH2), 4.32–4.33 (t, 2H, NCH2CH2), 5.41 (s, 2H, OCH2),
6.78–6.79 (d, 2H, ArH), 7.73–7.75 (d, 1H, ArH), 7.84–7.86 (d,
2H, ArH), 7.99 (s, 1H, ArH), 8.04–8.05 (d, 1H, ArH).
Synthesis of (E)-4-(2-(ethyl(4-((2-((2-ethylhexyl)oxy)-4-nitro-
phenyl)diazenyl)phenyl)amino)ethoxy)-4-oxobutanoic acid (6).
Compound 6 was synthesized using a similar procedure to that
for 4 as red powder. Yield: 60.92%. 1H NMR (500 MHz, CDCl3,
d (ppm)): 0.88–0.91 (t, 3H, CH3), 0.96–0.99 (t, 3H, CH3), 1.23–
1.26 (t, 3H, NCH2CH3), 1.32–1.37 (m, 8H, (CH2)2CH2,
(CH2)2CH2, CH2CH3), 1.88–1.90 (t, 1H, CH(CH2)3), 2.62–2.67
(m, 4H, (CH2)2COOH), 3.49–3.54 (m, 2H, NCH2), 3.66–3.69 (t,
2H, OCH2), 4.09–4.10 (d, 2H, NCH2CH2), 4.31–4.34 (t, 2H,
NCH2CH2), 6.77–6.79 (d, 2H, ArH), 7.65–7.67 (d, 1H, ArH),
7.85–7.89 (m, 4H, ArH).
Synthesis
of
(E)-2-(ethyl(4-((4-nitro-2-((perfluorophenyl)
methoxy)phenyl) diazenyl)phenyl)amino)ethanol (E2). The chro-
mophore E2 was synthesized using a similar procedure to that for
E1. Yield: 40.39%. 1H NMR (500 MHz, CDCl3, d (ppm)): 1.24–
1.27 (t, 3H, CH3), 3.56–3.57 (d, 2H, CH2OH), 3.61–3.64 (t, 2H,
CH2CH3), 3.89–3.90 (d, 2H, NCH2CH2), 5.40 (s, 2H, OCH2),
6.79–6.81 (d, 2H, ArH), 7.73–7.75 (d, 1H, ArH), 7.84–7.86 (d,
2H, ArH), 7.97–8.00 (t, 1H, ArH), 8.04 (d, 1H, ArH). Elemental
analysis calcd (%) for C12H19F5N4O2: C, 54.12; H, 3.75; N, 10.98.
Found: C, 54.40; H, 3.80; N, 10.54. MS (ESI): exact mass calcd
for C12H19F5N4O2 [M + H]+, 511.41. Found: 511.30. [M ꢀ H]ꢀ,
509.41. Found: 509.30.
Synthesis of six-branched chromophore S1
Compound 1 (0.52 g, 1 mmol), 4 (3.31 g, 8 mmol), EDC$HCl
(2.09 g, 11 mmol) and DMAP (0.24 g, 2 mmol) were dissolved in
mixed solvent of CH2Cl2 and THF (v : v ¼ 3 : 1). The mixture
was stirred at room temperature for 72 h. The resulting solution
was diluted with CH2Cl2 and washed with brine and water and
the organic phase was dried over MgSO4. After the solvent was
evaporated under reduced pressure, the residue was purified by
silica column chromatography on silica gel using a mixture of
CH2Cl2/THF (v : v ¼ 40 : 1) as the eluent to yield the red powder
S1. Yield: 46.21%. 1H NMR (500 MHz, CDCl3, d (ppm)): 1.21–
1.25 (m, 18H, CH2CH3), 2.01 (s, 3H, CCH3), 2.61–2.63 (m, 24H,
(OCCH2)2), 3.48–3.65 (m, 24H, NCH2), 4.04–4.05 (d, 6H,
CHCH2O), 4.28–4.44 (m, 18H, OCH2, CHCH2O), 5.35–5.37
(t, 3H, CHCH2), 6.73–6.93(m, 24H, ArH), 7.86–7.90 (m, 24H,
Synthesis of (E)-2-(ethyl(4-((2-((2-ethylhexyl)oxy)-4-nitro-
phenyl)diazenyl) phenyl)amino)ethanol (E3). The chromophore
E3 was synthesized in a similar procedure to that for E1. Yield:
69.21%. 1H NMR (500 MHz, CDCl3, d (ppm)): 0.88–0.91 (t, 3H,
CH3), 0.96–0.99 (t, 3H, CH3), 1.20–1.22 (d, 3H, NCH2CH3),
1.22–1.27 (t, 4H, CH(CH2)2), 1.33–1.38 (m, 4H, CH2CH3), 1.89
(s, 1H, CH(CH2)2), 3.55–3.59 (t, 2H, NCH2CH3), 3.61–3.63
(t, 2H, CH2OH), 3.89–3.90 (d, 2H, OCH2), 4.09–4.10 (d, 2H,
NCH2), 6.80–6.81 (d, 2H, ArH), 7.66–7.68 (d, 1H, ArH), 7.86–
7.90 (m, 4H, ArH). Elemental analysis calcd (%) for
C24H34N4O4: C, 65.14; H, 7.74; N, 12.66. Found: C, 65.11; H,
7.72; N, 12.51. MS (ESI): exact mass calcd for C24H34N4O4
9204 | J. Mater. Chem., 2012, 22, 9202–9208
This journal is ª The Royal Society of Chemistry 2012