A R T I C L E S
Jaska et al.
16 2 2
H N (M ): found 258.15145, calcd 258.14996.
11B
+
layer. In addition, the short B‚‚‚N interactions observed in 3
provide advantageous structural reinforcement in conjunction
with established π-stacking motifs, which may lead to enhanced
rigidity, closer molecular contacts, and better overall electron
transport properties.
HR-MS for C16
Cyclic voltammetry (vs SCE): E1/2 (THF) ) -1.89 (rev), -1.21 (rev),
0.69 (irrev) V; E1/2 (CH Cl ) ) -1.25 (rev), +0.76 (irrev) V. Anal.
Calcd for C16 (257.93): C, 74.50; H, 6.25; N, 10.86. Found:
+
2
2
16 2 2
H N B
C, 72.85; H, 7.42; N, 9.28.
Synthesis of 3: A solution of pyridazine (0.057 g, 0.71 mmol) in
toluene (3 mL) was added dropwise over 5 min to a solution of the
Pr-DBB (0.313 g, 0.695 mmol) in toluene (10 mL) at 25 °C. After
Experimental Section
i
General Procedures. All reactions and product manipulations were
performed under an atmosphere of purified argon using vacuum line
techniques or in an M-Braun glovebox using dried solvents. See the
Supporting Information for further details.
stirring for 3 days, the volatiles were removed, and the residue was
dissolved in CH
material. The solvent was removed, and the solid was extracted with
,2,4-trimethylpentane (15 mL). Removal of the solvent followed by
2 2
Cl (25 mL) and filtered to remove any insoluble
2
Synthesis of 1: A solution of pyridazine (0.042 g, 0.52 mmol) in
recrystallization from hexanes at -35 °C afforded 3 as X-ray quality
dark red-black crystals. An analytically pure sample of 3 was obtained
CH
and 4,4′-B (ca. 0.179 g, ca. 0.490 mmol) in CH
After 16 h, the volatiles were removed, and the residue was extracted
with CH Cl
2
Cl
2
(5 mL) was slowly added dropwise to a mixture of H-DBB
2
2
Cl (10 mL) at 25 °C.
by passing a CH
Yield: 0.129 g (59%). H NMR (CDCl
Hz, H-6), 8.36 (s, H-2), 7.79 (dd, JHH ) 1, 12 Hz, H-4), 7.53 (d, JHH
12 Hz, H-5), 6.19 (dd, JHH ) 3, 6 Hz, H-7), 3.14 (septet, JHH ) 7
2 2
Cl solution through a short column of neutral alumina.
1
3
): δ ) 8.74 (dd, JHH ) 3, 6
2
2
(3 × 10 mL) and filtered through Celite. The solvent was
removed, and the resulting solid was loaded onto a short column (3
cm) of neutral alumina. The column was washed through with hexanes
)
i
i
11
1
Hz, Pr-CH), 1.41 (d, JHH ) 7 Hz, Pr-CH
3
). B{ H} NMR (CDCl
3
):
2 2
(15 mL), followed by elution of 1 with CH Cl . Removal of the solvent
δ ) 24.3 (br s). 13C{ H} NMR (CDCl
1
): δ ) 148.1 (s, C-3), 140.5 (s,
3
gave a black-red solid, which could be further purified by sublimation
at 80 °C. X-ray quality crystals of 1 were obtained via slow evaporation
C-4), 133.8 (s, C-6), 127.9 (br s, C-5), 121.0 (s, C-2), 108.9 (s, C-7),
i
i
3
(
6.2 (s, Pr-CH), 23.9 (s, Pr-CH
3
), C-1 was not observed. UV-Vis (ꢀ
Cl ) ) 545 (2.0), 509 (1.6), 323 (1.6),
75 (2.0), 228 (2.2) nm; λmax (hexanes) ) 536 (1.3), 500 (1.0), 332
0.6), 317 (0.8), 304 (0.8), 277 (0.9) nm. Fluorescence (cyclohexane):
2
of a CH Cl
2
solution at 25 °C. Yield: 0.028 g (ca. 41% based on 60:
4
-1
-1
10 L mol cm )): λmax (CH
2
2
4
0 ratio of H-DBB/4,4′-B).
2
(
λ
11
+
max ) 554, 586 nm, Φ
14.21343, calcd 314.21256. Cyclic voltammetry (vs SCE): E1/2 (THF)
-1.85 (rev), -1.24 (rev), +0.65 (irrev) V; E1/2 (CH Cl ) ) -2.02
irrev), -1.28 (rev), +0.81 (irrev) V. Anal. Calcd for C20
314.04): C, 76.49; H, 7.70; N, 8.92. Found: C, 75.27; H, 7.58; N,
F
24 2 2
) 0.08. HR-MS for C20H N B (M ): found
3
)
(
2
2
24 2 2
H N B
(
8
.68. TGA: Tonset ) 150 °C, T5% ) 208 °C.
Synthesis of 4: A solution of phthalazine (0.091 g, 0.70 mmol) in
i
toluene (3 mL) was added dropwise over 5 min to a solution of Pr-
DBB (0.313 g, 0.695 mmol) in toluene (10 mL) at 25 °C. After stirring
for 3 days, the volatiles were removed, and the residue was dissolved
in CH Cl (25 mL) and filtered to remove any insoluble material. The
2 2
solvent was removed, and the solid was washed with 2,2,4-trimethyl-
pentane (15 mL) and hexanes (15 mL) and dried in vacuo overnight at
1H NMR (CDCl
8 Hz, H-2), 7.85 (dd, JHH ) 6, 12 Hz, H-4), 7.61 (d, JHH ) 12 Hz,
): δ ) 8.91 (dd, JHH ) 3, 6 Hz, H-6), 8.57 (d, JHH
3
)
H-5), 7.37 (dd, JHH ) 6, 8 Hz, H-3), 6.35 (dd, JHH ) 3, 6 Hz, H-7).
11
1
13
1
B{ H} NMR (CDCl
3
): δ ) 24.5 (br s). C{ H} NMR (CDCl ): δ
3
)
1
ca. 140 (br s, C-5), 139.5 (s, C-4), 134.3 (s, C-6), 128.4 (s, C-3),
2
5 °C to afford 4 as an orange-brown solid. An analytically pure
sample of 4 was obtained by passing a CH Cl solution through a short
column of neutral alumina. Yield: 0.230 g (91%).
4
25.4 (s, C-2), 110.0 (s, C-7), C-1 was not observed. UV-Vis (ꢀ (10
-
1
-1
2
2
L mol cm )): λmax (CH
2
Cl
2
) ) 557 (1.4), 523 (1.0), 321 (0.2), 271
(
0.6), 240 (0.7) nm; λmax (hexanes) ) 546 (1.5), 510 (1.0), 486 (0.7),
2
72 (0.6), 221 (0.9) nm. Fluorescence (cyclohexane): λmax ) 558, 586
-
4
nm, Φ
F
) 0.08. Fluorescence lifetime (1.31 × 10 M, cyclohexane):
11B
(M ): found
30.11795, calcd 230.11866. Cyclic voltammetry (vs SCE): E1/2 (THF)
-1.85 (rev), -1.16 (rev), +0.56 (irrev) V; E1/2 (CH Cl ) ) -2.14
irrev), -1.35 (rev), +0.60 (irrev) V. Anal. Calcd for C14
229.88): C, 73.15; H, 5.26; N, 12.19. Found: C, 72.05; H, 5.48; N,
1.58.
Synthesis of 2: A solution of pyridazine (0.069 g, 0.86 mmol) in
2
+
τ ) 5.0 ns (ø ) 3.6). HR-MS for C14
2
)
(
(
1
H N
12 2
2
2
2
12 2 2
H N B
toluene (3 mL) was added dropwise over 5 min to a solution of Me-
DBB (0.343 g, 0.87 mmol) in toluene (10 mL) at 25 °C. After stirring
for 24 h, the volatiles were removed, and the resulting solid was washed
with cold 2,2,4-trimethylpentane (-78 °C) and dried in vacuo. The
solid was then loaded onto a short column of neutral alumina, flushed
through with hexanes, and finally eluted with CH
volatiles provided 2 as a dark red solid. Yield: 0.116 g (52%). H
NMR (CDCl ): δ ) 8.71 (dd, JHH ) 3, 6 Hz, H-6), 8.31 (s, H-2), 7.68
d, JHH ) 12 Hz, H-4), 7.47 (d, JHH ) 12 Hz, H-5), 6.17 (dd, JHH ) 3,
2
Cl
2
. Removal of the
1H NMR (CDCl
): δ ) 7.98 (s, H-2), 7.72 (d, JHH ) 12 Hz, H-4),
3
1
7.51 (d, JHH ) 12 Hz, H-5), 7.10 (s, H-6), 7.01 (dd, JHH ) 3, 5 Hz,
i
3
H-8), 6.72 (dd, JHH ) 3, 5 Hz, H-9), 3.01 (septet, JHH ) 7 Hz, Pr-
i
11
1
(
CH), 1.35 (d, JHH ) 7 Hz, Pr-CH
3
). B{ H} NMR (CDCl
3
): δ )
1
1
1
13
1
6
Hz, H-7), 2.58 (s, CH
3
). B{ H} NMR (CDCl
): δ ) 142.5 (s, C-3), 137.6 (s, C-4), 133.8 (s,
C-6), 127.6 (br s, C-5), 123.9 (s, C-2), 108.9 (s, C-7), 24.1 (s, CH ),
3
): δ ) 24.0 (br s).
24.1 (br s). C{ H} NMR (CDCl ): δ ) 148.3 (s, C-3), 141.6 (s, C-4),
3
13
1
C{ H} NMR (CDCl
3
134.6 (s, C-7), 129.3 (br s, C-5), 127.8 (s, C-9), 126.2 (s, C-8), 120.8
i
i
i
3
(s, C-2), 66.8 (s, C-6), 36.1 (s, Pr-CH), 23.6 (s, Pr-CH
3
-1
), 23.4 (s, Pr-
4
-1
-1
4
-1
C-1 was not observed. UV-Vis (ꢀ (10 L mol cm )): λmax (CH
Cl ) ) 546 (1.7), 510 (1.3), 340 (0.8), 326 (0.9), 275 (1.0), 223 (1.0)
nm; λmax (hexanes) ) 537 (0.8), 501 (0.6), 334 (0.4), 319 (0.5), 276
0.6) nm. Fluorescence (cyclohexane): λmax ) 551, 583 nm, Φ ) 0.08.
2
-
CH
(CH
) 466 (1.9), 441 (2.3), 288 (1.9), 213 (2.9) nm. Fluorescence
3
), C-1 was not observed. UV-Vis (ꢀ (10 L mol cm )): λmax
2
2 2
Cl ) ) 471 (1.5), 447 (1.7), 291 (1.4), 228 (1.3) nm; λmax (hexanes)
1
1
(
F
F
26 2 2
(cyclohexane): λmax ) 521 nm, Φ ) 0.02. HR-MS for C24H N B
1
0894 J. AM. CHEM. SOC. VOL. 128, NO. 33, 2006
9