246
L. He et al. / Dyes and Pigments 120 (2015) 245e250
2. Experimental
rate such that the temperature remained below 5 ꢀC. The pH of the
coupling reaction was maintained near pH 5 by the addition of solid
NaOAc$3H2O. The coupling step was continued for 3 h and the
mixture was stirred overnight (14 h). The precipitate was collected
by filtration, washed with H2O, and air dried to give 2b as a reddish
2.1. General
All chemicals used in this study were purchased from either
Aldrich Chemical Company or Fisher Scientific Company. Thin layer
orange solid (3.71 g, 65%). lmax/εmax (EtOH)
¼
444 nm/
chromatography (TLC) was conducted using Whatman 250
mm
23,500 L molꢁ1 cmꢁ1; TLC: Rf ¼ 0.79 (hexane:EtOAc/1:1); 1H NMR
silica gel 60A plates. Mass spectral data were generated using a Jeol
HX110 double-focusing mass spectrometer, employing FAB(þ) or
ESI(þ) as the ionization method, and 1H NMR spectra were recor-
ded on a General Electric Omega 300 MHz spectrometer using
CDCl3 as the solvent.
(CDCl3):
d
1.21e1.26 (t, 6H, J ¼ 4.0 Hz),
d 3.43e3.50 (q, 4H,
J ¼ 4.1 Hz),
d
d
6.71e6.74 (d, 2H, J ¼ 7.54 Hz),
d 7.65e7.69 (d, 2H,
J ¼ 7.53 Hz),
7.86e7.92 (dd, 4H, J ¼ 8.39 Hz); FAB-MS (positive ion)
m/z (rel. int.): 572 (M þ H, 76), 571 (Mþ, 100); ESI-MS (þ),
C
22H19F13N3 [MþH]þ: calcd. 572.1371, obsd. 572.1365.
2.2. Synthesis of arylamines 1a-1b
2.4. X-ray analysis
A mixture of nonafluorobutyl iodide (9.80 g, 27.8 mmol), 4-
iodoaniline (5.59 g, 25 mmol), and copper bronze (5.34 g,
83.3 mmol) in DMSO (50 mL) was stirred at 120 ꢀC for 10 h. The
inorganic salts were removed by filtration, and the filtrate was
diluted with H2O (100 mL) and diethyl ether (100 mL). After stirring
for 5 min, the organic layer was collected and washed five times
with H2O (100 mL) to remove DMSO and nonafluorobutyl iodide,
and evaporated under reduced pressure. The mixture was distilled
to give 1a (bp 108e111 ꢀC, 28 in Hg) as a pale yellow liquid (4.55 g,
59%). TLC: Rf ¼ 0.59 (hexane:EtOAc/1:1). EI-MS m/z (rel. int.): 311
(Mþ, 31), 295 (54), 142 (100).
X-ray quality crystals of dye 2b were grown by slow evaporation
of an acetone solution at room temperature. The selected crystal
was mounted on a nylon loop using a small amount of Paratone N
oil, and X-ray measurements were made on a Bruker-Nonius X8
Apex2 diffractometer at 110 K. The unit cell dimensions were
determined from a symmetry constrained fit of 4145 reflections
with 5.24ꢀ < 2
q
< 42.22ꢀ. The data collection strategy involved the
use of a number of
u
and 4 scans to collect data up to 42.32ꢀ (2
q)
and the frame integration was performed using SAINT [14]. The
resulting raw data was scaled and absorption corrected using a
multi-scan averaging of symmetry equivalent data using SADABS
[15].
A mixture of 4-tridecafluorohexyl iodide (12.38 g, 27.8 mmol),
4-iodoaniline (5.59 g, 25 mmol), and copper bronze (5.34 g,
83.3 mmol) in DMSO (50 mL) was stirred at 120 ꢀC for 10 h. Inor-
ganic salts were removed by filtration, and the filtrate was diluted
with H2O (100 mL) and diethyl ether (100 mL). After stirring for
5 min, the organic layer was collected and washed five times with
H2O (100 mL) to remove DMSO and 4-tridecafluorohexyl iodide,
and evaporated under reduced pressure. The crude product was
distilled to give 1b (bp 110e114 ꢀC, 28 in Hg) as a pale yellow liquid
(4.95 g, 48%) [13]. TLC: Rf ¼ 0.64 (hexane:EtOAc/1:1). FAB-MS
(positive ion) m/z (rel. int.): 412 (M þ H, 73), 411 (Mþ, 100).
Both perfluoroalkyl-substituted arylamines were used without
further characterization.
The structure was solved by direct methods using the SIR92
program [16]. All non-hydrogen atoms were obtained from the
initial solution and the hydrogen atoms were introduced at ideal-
ized positions and were allowed to refine isotropically. The struc-
tural model was fit to the data using full matrix least-squares based
on F2. The calculated structure factors included corrections for
anomalous dispersion from the usual tabulation. The structure was
refined using the XL program from SHELXTL [17], graphic plots
were produced using the NRCVAX crystallographic program suite.
Crystallographic data are summarized in Table 1. These data have
been deposited with the Cambridge Crystallographic Data Centre
and was assigned CCDC 1057216.
2.3. Synthesis of dyes 2a-2b
2.5. Electron density calculations
To a stirred suspension of compound 1a (3.11 g, 10 mmol) in 2 M
HCl (15 mL) at 0e5 ꢀC, NaNO2 (0.71 g, 10.2 mmol) in H2O (3 mL) was
slowly added. The diazotization step was continued for 30 min and
excess HNO2 was destroyed by the addition of solid sulfamic acid.
The resultant diazonium salt solution was added dropwise to N,N-
diethylaniline (1.53 g, 10.2 mmol) dissolved in HOAc (25 mL), at a
rate such that the temperature remained below 5 ꢀC. The pH of the
coupling reaction was maintained near pH 5 by the addition of solid
NaOAc$3H2O. The coupling step was continued for 3 h and the
mixture produced was stirred overnight. The precipitate was
collected by filtration, washed with H2O, and air dried to give 2a as
an orange solid (3.49 g, 74%). lmax/εmax (EtOH) ¼ 444 nm/
22,300 L molꢁ1 cmꢁ1; TLC: Rf ¼ 0.82 (hexane:EtOAc/1:1). 1H NMR
Electron density calculations were conducted using PiSystems
version 6.3, Copyright 2002e2013 Neutronix Software. This soft-
ware allows the semi-empirical quantum-theoretical calculation of
the
p system of organic molecules. Values obtained from calcu-
lating electron-density alterations correspond to increase
(decrease) of the negative charge at a specific atom. The values
obtained have the unit number of electrons and the algebraic sum
of these numbers over all
show the difference in the
between the ground and the electronically excited state at each
p
p
atoms is zero. Further, these values
-electron densities (¼charge orders)
atom of the
p system, i.e. the shift of the electrons in the p system
when it is electronically excited.
3. Results and discussion
3.1. Dye synthesis
(CDCl3):
d
1.21e1.26 (t, 6H, J ¼ 4.0),
d
3.43e3.50 (q, 4H, J ¼ 4.0),
7.86e7.92
d
6.71e6.74 (d, 2H, J ¼ 7.5),
d
7.52e7.68 (d, 2H, J ¼ 7.5),
d
(dd, 4H, J ¼ 8.4). FAB-MS (positive ion) m/z (rel. int.): 472 (M þ H,
78), 471 (Mþ, 100), 470 (36).
To a stirred suspension of compound 1b (4.11 g, 10 mmol) in 2M
HCl (15 mL) at 0e5 ꢀC, NaNO2 (0.71 g, 10.2 mmol) in H2O (3 mL) was
slowly added. The diazotization step was continued for 30 min and
excess HNO2 was destroyed by adding solid sulfamic acid. The
resultant diazonium salt solution was added drop wise to N,N-
diethylaniline (1.53 g, 10.2 mmol) dissolved in HOAc (25 mL), at a
The synthesis of monoazo dyes having a perfluoroalkyl chain in
the diazo component is illustrated in Fig. 1. In step 1, 4-(non-
afluorobutyl)aniline and 4-(tridecafluorohexyl)aniline were pre-
pared by the reaction of 4-iodoaniline with the corresponding
perfluoroalkyl iodides (RI) in the presence of copper bronze [18].
Diazotization of 4-(perfluoroalkyl)anilines (1) followed by coupling