Turning-on the Quenched Fluorescence of Azomethines
125.6, 125.1, 123.2, 120.9, 120.6, 120.4, 119.9, 119.6, 116.7, 55.6,
40.9, 37.2, 31.9, 30.1, 24.1, 23.0, 22.6, 14.4 ppm. HRMS (+ve): m/z
calcd. for [C39H43N + H]+ 526.3396; found 526.3392.
0.219 mmol). The title compound was obtained as a yellow solid
(130 mg, 89%) after purification by column chromatography (hex-
ane/ethyl acetate, 70:30). 1H NMR (CDCl3): δ = 8.69 (s, 1 H), 8.05
(s, 1 H), 7.91 (dd, 2 H), 7.45 (dd, 2 H), 7.28–7.39 (m, 5 H), 2.06
(dt, 8 H), 1.10 (m, 24 H), 0.83 (dt, 12 H), 0.64 (br. s, 8 H) ppm.
13C NMR (CDCl3): δ = 160.3, 152.7, 152.5, 151.7, 151.2, 144.0,
141.2, 139.9, 136.4, 129.64, 127.2, 123.3, 123.2, 123.0, 121.0, 120.6,
119.9, 119.8, 116.5, 55.9, 55.6, 41.0, 40.8, 32.2, 32.0, 31.9, 30.4,
30.2, 29.7, 29.6, 24.2, 23.0, 14.5, 14.4 ppm. HRMS (+ve): m/z calcd.
for [C77H100N2 + H]+ 1053.7886; found 1053.7884.
(N2E,N7E)-N2,N7-Bis[(9H-fluoren-2-yl)methylene]-9,9-dihexyl-
9H-fluorene-2,7-diamine (8): Obtained from 9,9-dihexyl-9H-fluor-
en-2-ylamine (14; 150 mg, 0.411 mmol) and 9H-fluorene-2-carbal-
dehyde (290 mg, 1.31 mmol). The title compound was obtained as
an orange solid (110 mg, 37 %) after purification by column
chromatography (hexane/ethyl acetate, 80:20). 1H NMR (CDCl3):
δ = 8.68 (s, 1 H), 8.23 (s, 1 H), 7.93 (dd, 3 H), 7.73 (s, 1 H), 7.61
(s, 1 H), 7.39 (dd, 2 H),7.28 (m, 2 H), 4.02 (br. s, 2 H), 2.04 (t, 2 H),
1.08 (m, 6 H), 0.8 (t, 3 H), 0.74 (t, 2 H) ppm. 13C NMR (CDCl3): δ
= 160.4, 152.7, 151.5, 144.9, 144.0, 143.7, 141.8, 140.3, 136.4, 129.3,
127.2, 126.9, 125.4, 123.0, 120.9, 120.8, 120.6, 120.1, 118.1, 55.9,
55.8, 40.5, 37.4, 32.2, 30.2, 29.6, 24.2, 22.9, 14.4 ppm. HRMS
(+ve): m/z calcd. for [C53H52N2 + H]+ 717.4130; found 717.4131.
(E)-N-[(9,9-Dihexyl-9H-fluoren-2-yl)methylene]-9H-fluoren-2-amine
(3): Obtained from 9H-fluoren-2-ylamine (120 mg, 0.662 mmol)
and 9,9-dihexyl-9H-fluorene-2-carbaldehyde (18; 200 mg,
0.55 mmol). The title compound was obtained as a light-yellow so-
lid (180 mg, 62%) after purification by column chromatography
1
(hexane/ethyl acetate, 90:10). H NMR ([D6]acetone): δ = 8.64 (s,
1 H), 7.97 (s, 1 H), 7.76–7.88 (m, 5 H), 7.56 (d, 1 H), 7.49 (s, 1 H),
7.31–7.40 (m, 6 H), 3.97 (s, 2 H), 2.06 (t, 4 H), 1.1 (m, 12 H), 0.77
(t, 6 H), 0.65 (t, 4 H) ppm. 13C NMR (CDCl3): δ = 160.7, 152.0,
151.7, 144.9, 144.8, 143.7, 141.8, 140.7, 135.6, 129.2, 128.3, 127.3,
127.2, 127.1, 126.8, 125.4, 123.4, 122.9, 120.8, 120.7, 120.6, 126.5,
120.2, 120.1, 118.0, 56.1, 55.6, 40.7, 37.3, 31.9, 31.3, 30.1, 24.1,
22.9, 14.4 ppm. HRMS (+ve): m/z calcd. for [C39H43N + H]+
526.3396; found 526.3392.
(E)-N2-[(9,9-Dihexyl-9H-fluoren-2-yl)methylene]-9,9-dihexyl-9H-
fluorene-2,7-diamine (4): Obtained from 9,9-dihexyl-9H-fluorene-
2,7-diamine (14; 170 mg, 0.411 mmol) and 9,9-dihexyl-9H-fluo-
rene-2-carbaldehyde (18; 540 mg, 1.5 mmol). The title compound
was obtained as a yellow solid (90 mg, 31%) after purification by
1
column chromatography (hexane/ethyl acetate, 70:30). H NMR
(E)-N-[(9H-Fluoren-2-yl)methylene]-9H-fluoren-2-amine (9): To 9H-
fluoren-2-ylamine (93.3 mg, 0.51 mmol) was added 9H-fluorene-2-
carbaldehyde (100 mg, 0.51 mmol) in anhydrous ethanol, under N2
and a catalytic amount of TFA. The solution was stirred at room
temperature for 12 h until a yellow precipitate was formed. The
mixture was filtered and the product was isolated as a yellow solid
(183.7 mg, 100%). The product was insoluble in common deuter-
ated solvents for NMR characterization and its subsequent charac-
terization was not possible.
(CDCl3): δ = 8.67 (s, 1 H), 8.01 (s, 1 H), 7.9 (dd, 4 H), 7.5 (dd, 1
H), 7.28–7.39 (m, 7 H), 6.65 (d, 2 H), 3.75 (br. s, 2 H), 2.08 (t, 8
H), 1.09 (m, 24 H), 0.8 (t, 12 H), 0.70 (t, 8 H) ppm. 13C NMR
(CDCl3): δ = 160.6, 159.9, 153.2, 152.6, 152.0, 150.3, 146.2, 140.7,
140.3, 139.5, 135.8, 132.6, 129.3, 129.2, 128.3, 128.2, 127.3, 123.4,
122.8, 120.7, 116.6, 116.5, 114.4, 110.2, 55.6, 55.3, 41.3, 40.8, 32.0,
31.9, 30.2, 30.1, 24.1, 23.1, 23.0, 14.4 ppm. HRMS (+ve): m/z calcd.
for [C51H68N2 + H]+ 709.5383; found 709.5386.
(N2E,N7E)-N2,N7-Bis[(9,9-dihexyl-9H-fluoren-2-yl)methylene]-9,9-
dihexyl-9H-fluorene-2,7-diamine (5): Obtained from 9,9-dihexyl-
9H-fluorene-2,7-diamine (14; 150 mg, 0.411 mmol) and 9,9-di-
hexyl-9H-fluorene-2-carbaldehyde (18; 450 mg, 1.23 mmol). The ti-
tle compound was obtained as a yellow solid (150 mg, 53%) after
purification by column chromatography (hexane/ethyl acetate,
(E)-N-Benzylideneaniline (10): Obtained from benzaldehyde
(50 mg, 0.471 mmol) and aniline (44 mg, 0.471). The title com-
pound was obtained as an orange solid (30 mg, 35%) after purifica-
tion by column chromatography (hexane/ethyl acetate, 70:30). 1H
NMR (CDCl3): δ = 8.6 (s, 1 H), 7.98 (dd, 2 H), 7.53–7.55 (m, 3
H), 7.43 (dd, 2 H), 7.23–7.28 (s, 1 H) ppm. 13C NMR (CDCl3): δ
= 160.6, 152.5, 152.2, 145.6, 137.0, 131.6, 129.6, 129.1, 129.0, 126.2,
121.2 ppm.
1
90:10). H NMR (CDCl3): δ = 8.66 (s, 1 H), 8.0 (s, 1 H), 7.89 (dd,
1 H), 7.73–7.78 (m, 3 H), 7.45 (s, 1 H),7.28–7.39 (m, 5 H), 2.06 (t,
8 H), 1.07 (m, 24 H), 0.8 (dt, 12 H), 0.64 (t, 8 H) ppm. 13C NMR
(CDCl3): δ = 160.6, 152.6, 152.0, 151.4, 151.0, 145.0, 141.7, 141.2,
138.3, 135.6, 129.3, 127.4, 127.1, 125.9, 123.2, 121.5, 120.1, 119.7,
116.6, 102.2, 61.2, 55.4, 40.7, 31.9, 30.0, 24.1, 22.9, 15.6, 14.4 ppm.
HRMS (+ve): m/z calcd. for [C77H100N2 + H]+ 1053.7886; found
1053.7882.
(N2E,N7E)-N2,N7-Bis[(9,9-dihexyl-9H-fluoren-2-yl)methylene]-9H-
fluorene-2,7-diamine (6): Obtained from 9,9-dihexyl-9H-fluorene-2-
carboxaldehyde (18; 590 mg, 1.63 mmol) and 9H-fluorene-2,7-di-
amine (100 mg, 0.51 mmol). The title compound was obtained as
a yellow solid (230 mg, 51 %) after purification by column
chromatography (hexane/ethyl acetate, 80:20). 1H NMR (CDCl3):
δ = 8.66 (s, 1 H), 8.0 (s, 1 H), 7.9 (dd, 1 H), 7.78 (m, 3 H), 7.31–
7.39 (m, 5 H), 4.10 (br. s, 2 H), 2.07 (t, 8 H), 1.06 (m, 24 H), 0.78
(dt, 12 H), 0.63 (t, 8 H) ppm. 13C NMR (CDCl3): δ = 160.4, 152.7,
151.5, 144.9, 144.0, 143.7, 141.8, 140.3, 136.4, 130.8, 129.3, 127.2,
126.9, 125.4, 123.0, 120.8, 120.6, 120.1, 118.1, 55.9, 55.8, 40.7, 37.3,
32.2, 29.6, 24.2, 22.9, 14.4 ppm. HRMS (+): m/z calcd. for
[C65H76N2+ H]+ 885.6008; found 885.6004.
(E)-4-[(4-Cyanobenzylidene)amino]benzonitrile (11): Obtained from
4-formylbenzonitrile (100 mg, 0.72 mmol) and 4-aminobenzonitrile
(90 mg, 0.72). The title compound was obtained as a white solid
(158 mg, 95%) after purification by recrystallisation from ethanol.
1H NMR (CDCl3): δ = 8.77 (s, 1 H), 8.2 (d, 2 H), 7.97 (d, 2 H),
7.86 (d, 2 H), 7.46 (d, 2 H) ppm.
Supporting Information (see footnote on the first page of this arti-
cle): Absorbance and fluorescence spectra, cyclic voltammograms,
1
and H and 13C NMR spectra are provided.
Acknowledgments
The authors acknowledge financial support from the Natural Sci-
ences and Engineering Research Council Canada for Discovery,
Strategic Research, and Research Tools and Equipment. The Cen-
tre for Self-Assembled Chemical Structures and additional equip-
ment funding from the Canada Foundation for Innovation are also
acknowledged. W. G. S. also thanks the Alexander von Humboldt
Foundation for funding that allowed the completion of this work.
(N,NЈE,N,NЈE)-N,NЈ-[(9,9-Dihexyl-9H-fluorene-2,7-diyl)bis-
(methanylylidene)]bis(9,9-dihexyl-9H-fluoren-2-amine) (7): Obtained
from 9,9-dihexyl-9H-fluoren-2-ylamine (16; 245 mg, 0.702 mmol)
and 9,9-dihexyl-9H-fluorene-2,7-dicarbaldehyde (20; 98 mg,
[1] A. Bolduc, C. Mallet, W. G. Skene, Sci. China Chem. 2013, 56,
3–23.
Eur. J. Org. Chem. 2013, 2563–2572
© 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
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