Studies on the structure of N-phenyl-substituted hexaaza[1 6]paracyclophane: Synthesis, electrochemical properties, and theoretical calculation

Article abstract of DOI:10.1021/jo301436g

The N-phenyl-substituted hexaaza[1₆]paracyclophane (3, hexamer) has been synthesized successfully in two steps and the noncoplanar conformation was calculated by Gaussian program. The electrochemical properties exhibited lots of interesting res

Full text of DOI:10.1021/jo301436g

Article
pubs.acs.org/joc
Studies on the Structure of N‑Phenyl-Substituted Hexaaza[16]
paracyclophane: Synthesis, Electrochemical Properties, And
Theoretical Calculation
Te-Fang Yang,*,† Kuo Yuan Chiu,† Hsu-Chun Cheng,† Yen Wei Lee,† Ming Yu Kuo,*,†
and Yuhlong Oliver Su*,†,‡
†Department of Applied Chemistry, National Chi Nan University, University Road, Puli, Nantou, 545, Taiwan
‡Department of Materials Science and Engineering, National Chung Hsing University, 250, Kuo Kuang Road, Taichung, 402, Taiwan
S
* Supporting Information
ABSTRACT: The N-phenyl-substituted hexaaza[16]paracyclophane (3,
hexamer) has been synthesized successfully in two steps and the
noncoplanar conformation was calculated by Gaussian program. The
electrochemical properties exhibited lots of interesting results and each
overlapping oxidative wave contained two-electron transfer.
coupling of the reactant and the formation of the title
compound (3, hexamer). In order to rationalize the mass
spectrum of 3, the molecular model study on the fragmentation
of the structure of this compound was carried out as follows. At
first, a fragment of phenyl (C6H5) or N-phenyl (NC6H5) group
was removed piece by piece, starting from the parent structure
(3, hexamer). Then, after each time when a C6H5 or NC6H5
piece was removed, the m/z value of the remained species was
calculated and listed in Table S1 (Supporting Information). It
was found that the corresponding m/z values of the mass
spectrum matched very well to those listed in Table S1,
confirming the exact structure of the hexamer (3).
In order to confirm that the hexamer (3) was the cyclic
oligoarylamine, linear N6 (6), a similar compound which
contained six nitrogen atoms and was connected with phenyl
groups, was also synthesized (Scheme 2) and characterized by
spectral and electrochemical methods. The fragment of the
phenyl (C6H5), N-phenyl (NC6H5), or diphenylamine
(C6H5NC6H5) group was removed in a stepwise fashion from
linear N6. When a C6H5, NC6H5, or C6H5NC6H5 piece was
removed, the m/z value of the remained species was calculated
and listed in Table S2 (Supporting Information). Furthermore,
we herein report the electrochemical behaviors and spectral
changes of the hexamer (3) and linear N6.
INTRODUCTION
■
Oligoarylamines usually contain two or more oxidized forms so
that these compounds are widely used in hole-transporting
layer of OLEDs.1,2 With the increase in redox center and
aromatic-bridge conjugation, electron-transfer phenomena and
oxidized states of oligoarylamines have been widely investigated
by electrochemical and optical methods.3−7 Linear6 and star-
shaped5,7 oligoarylamines have attracted most interest with
their outstanding molecular-based electronic properties in
recent years. So far, cyclic oligoarylamines have not yet been
generally studied because of difficulties in the synthesis and
purification of these compounds.8−10 Although the synthesis of
some hexaaza[16]paracyclophane derivatives, cyclic oligoaryl-
amines, had been reported in a patent issued in 1993,10 the
indentification and characteristic data were not described. The
N-anisyl-substituted hexaaza[16]paracyclophane was studied by
Ito et al.,4a but the procedure for the synthesis consisted of
more than three steps. To stabilize the hexaaza[16]-
paracyclophane, the anisyl group was used on the para-position
substituent. Five redox couples were observed in the oxidation
part, and the optimized structure showed that this hexaaza-
[16]paracyclophane is coplanar by theoretical calculations.
In this study, we have successfully synthesized N-phenyl-
substituted hexaaza[16]paracyclophane (3, hexamer) in two
steps, starting with N,N′-diphenyl-p-phenylenediamine (1,
Scheme 1). Ullmann-type coupling reaction of 1 with 1-
bromo-4-iodobenzene provided p-phenylenediamine 2 (PD-
Br).11 Then, treatment of 2 with t-BuONa in the presence of a
catalytic amount of Pd(0) complex12 resulted in the self-
Received: July 30, 2012
Published: September 5, 2012
© 2012 American Chemical Society
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Scheme 1. Synthesis Pathway of the N-Phenyl-Substituted
Hexaaza[16]paracycphane (3, Hexamer)
Figure 1. Absorption (black line) and emission (blue line) spectra of
the hexamer (3) (excitation wavelength = 322 nm).
absorption peak and the emission band of the linear N6 were at
338 and 495 nm, respectively (Figure 2).
RESULTS AND DISCUSSION
■
Figure 1 shows the room-temperature absorption (black line)
and emission (blue line) spectra of the hexamer (3) in CH2Cl2.
The hexamer (3) exhibited a characteristic absorption at 322
nm. When the hexamer (3) was excited at 322 nm, an emission
at 474 nm (a blue light) was observed. On the other hand, the
Figure 2. Absorption (black line) and emission (blue line) spectra of
linear N6 (excitation wavelength = 338 nm).
Scheme 2. Synthesis Pathway of the Linear N6 (6)
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Figure 3. Cyclic voltammetry (left) and differential pulse voltammetry (right) of 1.0 × 10−3 M hexamer (3) in CH2Cl2 containing 0.1 M
(A)TBABF4, (B) TBAP, and (C)TBAPF6. Working electrode: glassy carbon. Scan rate: 0.1 V/s (Fc+/0 = +0.54 V).
The left half part of Figure 3 shows the cyclic voltammogram
(CV) of the hexamer (3) with different electrolytes in CH2Cl2.
In the oxidation process, two oxidation waves were observed at
Epa = +0.68 and +1.16 V (Epc = +0.55 and +1.06 V,
respectively) (Figure 3B, left) in TBAP/CH2Cl2. Both oxidative
waves appeared to be the overlapping of two redox couples. To
probe the anion effect, TBABF4 and TBAPF6 were also used as
the electrolyte (Figure 3A,C, left). Upon the change of
electrolyte, these two oxidative waves moved cathodically and
the ΔE between first wave and second wave were also changed.
The ΔEpa’s are +0.44, +0.48 and +0.54 V for TBABF4, TBAP,
and TBAPF6 as electrolytes, respectively. It indicates that the
interaction between the oxidized hexamer and electrolyte anion
decreased in the order BF4− > ClO4− > PF6− (the order of size
13
−
−
−
of anions was BF4 < ClO4 < PF6 ).
Figure 4. Controlled potential coulometry at Eappl = +0.84 V vs Ag/
AgCl for the hexamer (3) (1.0 × 10−6 mol) in CH2Cl2 (0.1 M TBAP).
To further resolve the electron-transfer number of the first
oxidation wave, controlled potential coulometry (CPC) and
differential pulse volammetry (DPV) were carried out.
Controlled potential coulometry (Figure 4) of 1.0 × 10−6
mol of hexamer (3) at +0.84 V indicated that two electrons per
molecule were removed in TBAP/CH2Cl2.7b,14
Table 1. Integration Areas of Peaks with Different
Electrolytes in Differential Pulse Voltammograms
electrolyte
second peak
first peak
1.18 × 10−7
1.45 × 10−7
1.16 × 10−7
1.17 × 10−7
1.33 × 10−7
1.17 × 10−7
Differential pulse voltammetry, as shown in the right half of
Figure 3, was used to identify the number of electrons oxidized
by calculating each integration area (Table 1). The integration
areas of peaks (Figure 3B, right) were 1.17 × 10−7 VA (first
wave) and 1.18 × 10−7 VA (second wave), respectively. As
indicated by the results of the electrochemical experiments, the
hexamer (3) has totally four-electron transfer in the oxidations,
and each oxidative wave has two-electron transfer. The CV and
DPV of the linear N6 were shown in Figure 5. Six oxidation
waves were observed at E = +0.48, +0.74, +0.96, +1.14, +1.21
and +1.33 V in the DPV. The CV and DPV of linear N6 were
obviously different from those of the hexamer (3). According to
the electrochemical studies, the results were another evidence
that the hexamer (3) is a cyclic oligoarylamine.
TBAP
TBABF4
TBAPF6
was presented in Table 2. The E1/2 of the first overlapping
oxidative wave were +0.54 (E1ox), +0.65 (E2ox) and +1.07
(E3ox), +1.14 (E4ox) V for the second overlapping oxidative
wave in the simulated results. The simulated CV of the hexamer
(3) has excellent agreement with experimental CV.
The characteristic absorption peak of the hexamer (3) at 322
nm had a molar extinction coefficient of 4.2 × 103 M−1 cm−1. In
the potential range of Eappl = +0.00 to +0.67 V, the spectra at
equilibrium were obtained (Figure 7A). As the potential was
moved anodically, the 322 nm peak of neutral hexamer (3)
gradually decreased in absorbance. At the same time, new
absorption peaks at 400 and 836 nm gradually increased. The
absorption at 836 nm was an intervalence charge-transfer (IV-
The digital simulation15 of experimental CV (Figure 6) was
carried out to distinguish the overlapping redox couples from
the two oxidation waves (Figure 3B). The reaction mechanism
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Figure 5. Cyclic voltammetry (left) and differential pulse voltammetry
(right) of 1.0 × 10−3 M linear N6 in CH2Cl2 containing 0.1 M TBAP.
Working electrode: glassy carbon. Scan rate: 0.1 V/s.
Figure 6. Experimental (red) and simulated (blue) CV of 1.0 × 10−3
M hexamer (3) (TBAP/CH2Cl2). Working electrode: glassy carbon
disk (area = 0.07 cm2). Scan rate: 0.1 V/s.
Table 2. Reaction Mechanism of the Hexamer (3) (TBAP/
CH2Cl2) in the Simulated CV
Figure 7. Spectral changes of 2.5 × 10−4 M hexamer (3) in CH2Cl2
containing 0.1 M TBAP at various applied potentials. Eappl = (A) +0.00
to +0.67; (B) +0.79 to +1.11 V.
electrochemical reactions
E0 (V)
(hexamer)+ + e = (hexamer)
(hexamer)2+ + e = (hexamer)+
(hexamer)3+ + e = (hexamer)2+
(hexamer)4+ + e = (hexamer)3+
+0.54
+0.65
+1.07
+1.14
ox
ox
ox
ox
E1
E2
E3
E4
the GAUSSIAN 09 program shows that the hexamer (3) was
not coplanar (Figure 9).19 The angles between phenyl rings
R1−R2, R3−R2, and R3−R4 are 58.2°, 84.9°, and 84.8° (Table
3), respectively, which make the environment of N1 atom
different from those of N2 and N3 atoms. That is, the
electronic interaction between NC6H5 bridge and TPPD unit is
minimal due to nearly perpendicular angles. This explains why
the oxidation behavior of the hexamer (3) is similar with that of
TPPD.
The spectral change of the linear N6 at various applied
potentials were also studied (Figure 10, 11), and the results
were obviously different from the hexamer (3). The spectral
changes of linear N6 are shown in Figures 10 and 11. In the
potential range of Eappl = +0.00 to +0.57 V, the first step
oxidation spectrum of linear N6 were obtained (Figure 10A).
As the potential shifted anodically, the characteristic absorption
at 338 nm gradually decreased while two new peaks (314 and
438 nm) and a broad band at 1420 nm grew. In another
potential range of Eappl = +0.70 to +0.90 V (Figure 10B) (the
second step oxidation spectrum), the absorbance at 314 nm
decreased dramatically. The broad band (1320 nm) in the near-
IR region grew. When the electrode potential ranging from
+0.93 to +1.10 V was applied (Figure 11A), the third step
oxidation spectral changes were obtained, two new absorption
peaks at 630 and 910 nm gradually increased and the
absorbance at 1320 nm decreased. If the applied potential
was further increased, from +1.25 to +1.50 V, the absorbance at
430, 590, and 910 nm decreased (Figure 11B).
CT) band.16 In another potential range of Eappl = +0.79 to
+1.11 V (Figure 7B), the absorbances 400 and 836 nm
decreased dramatically. A new peak grew at 586 nm.
The spectral change of the hexamer (3) in different oxidation
states was similar to that of N,N,N′,N′-tetraphenylphenylenedi-
amine (TPPD) (Figure 8).16b,17 As the potential shifted
positively, it was observed that the characteristic peak (312
nm) of TPPD gradually decreased, a new peak at about 408 nm
and a broad band at λmax = 856 nm in the near-IR region were
formed. When the applied potential was further moved
anodically, the absorbances of TPPD+ decreased and a new
band grew up at 598 nm. It is thus inferred that two cation
radical were separately localized at two TPPD units bridged by
two phenylnitrido moieties when the hexamer (3) was oxidized
to a dication state (Scheme 3) and the cation radicals appears
nearly independent to each other. Further oxidation by two
electrons generates two units of TPPD2+. It is worthy to note
that the absorbance between 1200 to 1700 nm decreased after
Eappl = +0.58 V (Figure 7A). It suggested that a weak IV-CT
band via the phenylnitrido (NC6H5) units was existed in the
low energy region18 and also confirmed the cyclic structure of
the hexamer (3) (two TPPD conformation was connected by
NC6H5 bridges). The weak energy transfer through the NC6H5
bridge was unusual (Scheme 3).
In order to confirm the hexamer (3) conformation, we seek
help from theoretical calculations. The optimized structure of
hexamer (3) calculated based on B3LYP/6-31G** level with
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Figure 9. Optimized structure and angles between phenyl rings of the
hexamer (3) calculated based on B3LYP/6-31G** level: Key: N, blue;
C, gray; H, white.
EXPERIMENTAL SECTION
■
N1-(4-bromophenyl)-N1,N4-diphenylphenylenediamine (2,
PD-Br). N1-(4-Bromophenyl)-N1,N4-diphenylphenylenediamine (2,
PD-Br) was synthesized by Ullmann coupling reaction.16 A mixture
of N1,N4-diphenylphenylenediamine (1) (2 g, 7.7 mmol), 4-
bromoiodobenzene (1 g, 3.5 mmol), copper powder (0.25 g, 3.9
mmol), potassium carbonate (0.54 g, 3.9 mmol), and 18-crown-6 ether
(0.01 g) in 1,2-dichlorobenzene (10 mL) was heated under N2
atmosphere at reflux temperature for 3 h. The reaction mixture was
then filtered. The filtrate was evaporated under vacuum, and the crude
product was purified by column chromatography on silica gel by using
dichloromethane/hexane (1:2) as the eluent to give PD-Br (2) as a
green syrup (340 mg, 11%): UV/vis (CH2Cl2) λmax/nm 314; MS
(FAB+) m/z = 415.368 ([M + H]+); 1H NMR (600 MHz, CD2Cl2) δ
(ppm) 7.32 (4H, J = 7.2 Hz, d), 7.28−7.26 (4H, m), 7.10−7.00 (8H,
m), 6.93 (4H, J = 6.0 Hz, d), 5.78 (NH, s); 13C NMR (150 MHz,
CD2Cl2) δ (ppm) 147.7, 147.5, 143.5, 140.6, 139.7, 132.0, 129.5,
129.4, 127.1, 124.1, 123.9, 123.7, 122.8, 120.8, 119.2, 117.4, 113.7.
Anal. Calcd for C24H19N2Br: C, 69.41; H, 4.61; N, 6.74. Found: C,
69.26; H, 4.88; N, 6.75.
Figure 8. Spectral change of 2.5 × 10−4 M TPPD at various applied
potenials in CH2Cl2 containing 0.1 M TBAP.
CONCLUSION
■
In conclusion, we have successfully synthesized the hexamer
(3) by a two-step synthesis method. A blue light emission at
474 nm of hexamer (3) was obtained. The hexamer (3) has
multiple redox potential and exhibits different interactions with
different electrolyte. Each of the oxidation processes was
reversible and stable after potential cycling continuously in
CH2Cl2. The results of the hexamer (3) and linear N6 exhibit
entirely different physical properties. According to these results,
the hexamer (3) has the potential for the hole-transporting
layer of light-emitting device.8b,10
N-Phenyl-Substituted Hexaaza[16]paracyclophane (3, Hex-
amer). Hexamer 3 was synthesized by heating at reflux temperature a
stirred solution of PD-Br (2, 0.22 g, 0.53 mmol), Pd2(dba)3 (15 mg,
0.016 mmol), dppf (18 mg, 0.032 mmol), and NatOBu (80 mg, 0.83
mmol) in toluene (50 mL) under N2 atmosphere for 72 h. The
reaction mixture was filtrated, and the filtrate was evaporated under
vacuum. The crude product was washed by hexane and methanol to
give hexamer 3 as a light yellow solid (140 mg, 26.3%): UV/vis
(CH2Cl2) λmax/nm 322; FT-IR (KBr, cm−1) 2922, 2856, 1594, 1491,
Scheme 3. Oxidation State of the Hexamer (3)
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Table 3. Mulliken Charges and Angles between Phenyl Rings of Hexamer (3) Calculated on the Basis of B3LYP/6-31G** Level
Mulliken charges
N1
N2
N3
N4
N5
N6
R1
R2
R3
−0.653
R4
−0.657
R5
−0.657
R6
−0.653
R7
−0.657
R8
−0.657
R9
+0.455
R10
+0.455
R11
+0.440
R12
+0.455
+0.455
+0.440
+0.226
+0.122
+0.122
+0.226
+0.122
+0.122
angles (deg)
R1−R2
R1−R7
R2−R7
R2−R3
R2−R8
R3−R8
R3−R4
R3−R9
R4−R9
58.2
71.4
71.4
84.9
75.9
74.7
84.8
74.8
75.8
R4−R5
R4−R10
R5−R10
R5−R6
R5−R11
R6−R11
R6−R1
R6−R12
R1−R12
57.8
71.1
71.7
84.6
75.7
74.8
84.6
74.7
75.8
Figure 10. Spectral change of (A) first and (B) second oxidation steps with 2.5 × 10−4 M linear N6 at various applied potenials in CH2Cl2 containing
0.1 M TBAP.
Figure 11. Spectral change of (A) third and (B) fourth oxidation steps with 2.5 × 10−4 M linear N6 at various applied potenials in CH2Cl2
containing 0.1 M TBAP.
1272; mp 201−202 °C; HRMS (FAB+) m/z calcd for C72H55N6 ([M
+ H]+) 1003.4492, found 1003.4498; 1H NMR (600 MHz, CD2Cl2) δ
(ppm) 7.45 (d, J = 8.4 Hz, 6H), 7.25 (t, J = 7.2 Hz, 12H), 7.06 (d, J =
16.8 Hz, 24H), 6.98 (s, 12H); 13C NMR (150 MHz, CD2Cl2) δ (ppm)
129.4, 129.3, 127.2, 126.9, 123.4, 123.1, 122.3, 120.6, 119.4, 117.2.
Anal. Calcd for C72H54N6: C, 86.20; H, 5.43; N, 8.38. Found: C, 86.05;
H, 5.65; N, 8.21.
7.18 (m, 6H), 7.08−7.03 (m, 4H), 6.97−6.61 (m, 8H), 6.82−6.77 (t, J
= 15.0 Hz, 1H); 13C NMR (150 MHz, DMSO-d6) δ (ppm) 147.7,
143.6, 140.0, 139.1, 129.3, 129.2, 127.0, 122.2, 121.8, 119.5, 118.2,
116.5.
N1,N4-bis(4-bromophenyl)-N1,N4-diphenylbenzene-1,4-dia-
mine (5, PD-Br2). A mixture of N1,N4-diphenylphenylenediamine (1,
0.5 g, 1.9 mmol), 1,4-dibromobenzene (4.5 g, 19 mmol), Pd(OAc)2
(17 mg, 4% mol), dppf (63 mg, 6% mol), and NatOBu (1.83 g, 19
mmol) in toluene (30 mL) was heated under N2 atmosphere at reflux
temperature for 21 h. The reaction mixture was then filtered. The
filtrate was evaporated under vacuum and the crude product was
purified by column chromatography on silica gel by using dichloro-
methane/hexane (1:4) as the eluent to give PD-Br2 (5) as a white solid
(0.52 g, 48%): mp 228−229 °C; HRMS (EI+) m/z calcd for
N1-(4-Phenyl)-N1,N4-diphenylbenzene-1,4-diamine (4, PD). A
mixture of N1,N4-diphenylphenylenediamine (1, 3.905 g, 15 mmol),
bromobenzene (0.785 g, 5 mmol), Pd2(dba)3 (27 mg, 0.03 mmol),
dppf (34 mg, 0.06 mmol), and NatOBu (1.44 g, 15 mmol) in toluene
(100 mL) was heated under N2 atmosphere at reflux temperature for
21 h. The reaction mixture was then filtered. The filtrate was
evaporated under vacuum and the crude product was purified by
column chromatography on silica gel by using dichloromethane/
hexane (1:2) as the eluent to give PD (4) as a white solid (0.5 g, 30%):
1
C30H22Br2N2 (M+) 568.0150, found 568.0157; H NMR (600 MHz,
CD2Cl2) δ (ppm) 7.33 (d, J = 10.2 Hz, 4H), 7.27 (t, J = 9.0 Hz, 4H),
7.09 (d, J = 9.0 Hz, 4H), 7.03 (t, J = 9.0 Hz, 2H), 6.97−6.94 (m, 8H);
1
mp 142−143 °C; H NMR (600 MHz, DMSO-d6) δ (ppm) 7.26−
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13C NMR (150 MHz, CD2Cl2) δ (ppm) 147.4, 147.2, 142.9, 132.2,
129.5, 125.9, 124.7, 124.4, 123.3, 114.4. Anal. Calcd for C30H22Br2N2:
C, 63.18; H, 3.89; N, 4.91. Found: C, 62.70; H, 3.62; N, 4.90.
Linear N6 (6). Linear N6 (6) was synthesized by heating at reflux
temperature a stirred solution of PD-Br2 (5, 0.257 g, 0.451 mmol),
Pd(OAc)2 (20 mg, 0.3% mol), BINAP (70 mg, 0.4% mol), PD (0.38 g,
1.13 mmol), and NatOBu (0.35 g, 3.61 mmol) in toluene (50 mL)
under N2 atmosphere for 48 h. The reaction mixture was filtrated, and
the filtrate was evaporated under vacuum and washed with MeOH and
acetone to give linear N6 (6) as a gray solid (0.195 g, 40%): UV/
vis(CH2Cl2) λmax/nm 338; mp 334−335 °C; MS (FAB+) m/z calcd
C78H60N6 ([M + H]+) 1081.235, found 1081.488; 1H NMR (600
MHz, CDCl3) δ (ppm) 7.23 (t, J = 15.3 Hz, 24H), 7.09 (d, J = 14.4
Hz, 16H), 7.01−6.98 (m, 20H); 13C NMR (150 MHz, CDCl3) δ
(ppm) 129.3, 125.3, 123.9. Anal. Calcd for C78H60N6: C, 86.64; H,
5.59; N, 7.77. Found: C, 86.59; H, 5.65; N, 7.67.
(2) (a) Adachi, C.; Nagai, K; Tamoto, N. Appl. Phys. Lett. 1995, 66,
2679. (b) Selby, T. D.; Kim, K. Y.; Blackstock, S. C. Chem. Mater.
2002, 14, 1685.
(3) (a) Lambert, C.; Schelter, J.; Fiebig, T.; Mank, D.; Trifonov, A. J.
Am. Chem. Soc. 2005, 127, 10600. (b) Lambert, C.; Amthor, S.;
Schelter, J. J. Phys. Chem. A 2004, 108, 6474.
(4) (a) Ito, A.; Yokoyama, Y.; Aihara, R.; Fukui, K.; Eguchi, S.; Shizu,
K.; Sato, T.; Tanaka, K. Angew. Chem., Int. Ed. 2010, 49, 8205.
(b) Ishibashi, K.; Tsue, H.; Sakai, N.; Tokita, S.; Matsui, K; Yamauchi,
J.; Tamura, R. Chem. Commun. 2008, 2812. (c) Kulszewicz-Bajer, I.;
Maurel, V.; Gambarelli, S.; Wielgus, I.; Djurado, D. Phys. Chem. Chem.
Phys. 2009, 11, 1362.
(5) (a) Louie, J.; Hartwig, J. F.; Fry, A. J. J. Am. Chem. Soc. 1997, 119,
11695. (b) Hirao, Y.; Ito, A.; Tanaka, K. J. Phy. Chem. A. 2007, 111,
2951. (c) Lambert, C.; Noll, G. Chem.Eur. J. 2002, 8, 3467.
̈
(6) (a) Grossmann, B.; Heinze, J.; Moll, T.; Palivan, C.; Ivan, S.;
Organic solvents were degassed by purging with prepurified
nitrogen gas and dried before use. Analytical grade tetra-n-
butylammonium perchlorate (TBAP) was obtained from ACROS
and recrystallized twice from ethyl acetate and then dried in vacuo
prior to use.
Gescheidt, G. J. Phys. Chem. B 2004, 108, 4669. (b) Coropceanu, V.;
Gruhn, N. E.; Barlow, S.; Lambert, C.; Durivage, J. C.; Bill, T. G.; Noll,
̈
́
G.; Marder, S. R.; Bredas, J.-L. J. Am. Chem. Soc. 2004, 126, 2727.
(7) (a) Shirota, Y. J. Mater. Chem. 2000, 10, 1. (b) Selby, T. D.;
Stickley, K. R.; Blackstock, S. C. Org. Lett. 2000, 2, 171. (c) Ito, A.;
Yamagishi, Y.; Fukui, K.; Inoue, S.; Hirao, Y; Furukawa, K; Kato, T.;
Tanaka, K. Chem. Commun. 2008, 6573.
A mass spectrometry experiment for the hexamer was carried out
with a high-resolution mass spectrometer. The ion source was
generated by fast atom bombardment (FAB). By using a xenon
laser, desorption of the analyte was operated. The acceleration voltage
for the operation of a positive-ion mode was 3 kV. The magnetic
sector mass analyzer was used for the HRMS measurements.
Electrochemistry was performed with a CHI Model 660 series
electroanalytical workstation. Cyclic voltammetry was conducted with
the use of a three-electrode cell in which a glassy carbon electrode
(area = 0.07 cm2) was used as working electrode. The glassy carbon
electrode was polished with 0.05 μm alumina on Buehler felt pads and
was ultrasonicated for 1 min to remove the alumina residue. The
auxiliary electrode is a platinum wire, and the reference electrode is a
homemade Ag/AgCl, KCl(satd) reference electrode. The spectroelec-
trochemical cell was composed of a 1 mm cuvette, a platinum gauze
thin layer as working electrode, a platinum wire as auxiliary electrode,
and an Ag/AgCl, KCl(satd) reference electrode. Absorption spectra
(8) (a) Ito, A.; Ono, Y.; Tanaka, K. Angew. Chem., Int. Ed. 2000, 39,
1072. (b) Wang, G.; Manabu, U.; Hajime, Y.; Takaharu, N.; Kenji, F.
Cyclic tertiary amine compound organic electroluminescent device
containing the compound, United States Patent US 6936189 B2, 2005.
(c) Tsue, H.; Ishibashi, K.; Tamura, R. Top. Heterocycl. Chem. 2008,
17, 73. (d) Ito, A.; Inoue, S.; Hirao, Y.; Furukawa, K.; Kato, T.;
Tanaka, K. Chem. Commun. 2008, 3242.
(9) Takemura, H. Curr. Org. Chem. 2009, 13, 1633.
(10) Hayata, H. Electrophotographic photoreceptor, Jpn. Kokai.
Tokkyo Koho JP 05323635, 1993.
(11) (a) Kelkar, A. A.; Patil, N. M.; Chaudhari, R. V. Tetrahedron Lett.
2002, 43, 7143. (b) Paine, A. J. J. Am. Chem. Soc. 1987, 109, 1496.
(12) (a) Zhao, H.; Tanjutco, C.; Thayumanavan, S. Tetrahedron Lett.
2001, 42, 4421. (b) Bronk, K.; Thayumanavan, S. Org. Lett. 2001, 3,
2057.
1
were measured with a UV/vis/near-IR spectrophotometer. H NMR
(13) Nafady, A.; Costa, P. J.; Colhorda, M. J.; Geiger, W. E. J. Am.
Chem. Soc. 2006, 128, 16587.
(14) Sivabalan, R.; Talawar, M. B.; Santhos, P.; Senthilkumar, N.;
Kavitha, B.; Gore, G. M.; Venugopalan, S. J. Hazard. Mater. 2007, 148,
573.
spectra were obtained with a 600 WB spectrometer. The fluorescence
spectrum was recorded on a spectrofluorometer.
ASSOCIATED CONTENT
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(15) The Digisim 3.03 Program was used in this study.
S
* Supporting Information
(16) (a) Lambert, C.; Noll, G. J. Am. Chem. Soc. 1999, 121, 8434.
̈
1
Calculated energy results for compound 3, copies of H and
(b) Yeh, S. J.; Tsai, C. Y.; Huang, C. Y.; Liou, G.-S.; Cheng, S.-H.
Electrochem. Commun. 2003, 5, 373.
13C NMR spectra for compounds 2, 3, and 6, UV−vis spectrum
for compound 3, and mass spectra for compounds 3 and 6.
This material is available free of charge via the Internet at
http://pubs.acs.org/.
(17) Chiu, K. Y.; Su, T. Z.; Huang, C. W.; Liou, G.-S; Cheng, S.-H. J.
Electroanal. Chem. 2005, 578, 283.
(18) (a) Wienk, M. M.; Janssen, R. A. J. J. Am. Chem. Soc. 1997, 119,
4492. (b) Ito, A.; Inoue, S.; Hirao, Y.; Furukawa, K.; Kato, T.; Tanaka,
K. Chem. Commun. 2008, 3242.
AUTHOR INFORMATION
(19) Gaussian 09, A.1 Revision, Frish, M. J. et al. (see the Supporting
Information ref S3 for the full citation).
■
Corresponding Author
*E-mail: tfyang@ncnu.edu.tw (T.-F.Y.), mykuo@ncnu.edu.tw
(M.Y.K.), yosu@ncnu.edu.tw (Y.O.S).
Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
■
We thank the National Science Council of Taiwan, R.O.C.
(NSC 97-2113-M-260-005-MY3, 99-2811-M-260-006, 99-
2113-M-260-007-MY3), for support of this work.
REFERENCES
(1) Forrest, S. R. Chem. Rev. 1997, 97, 1793.
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