F. Li et al. / Dyes and Pigments 132 (2016) 142e150
143
energy gaps. Among the electron-rich units, carbazole, dithieno
[
contain fused planar tricyclic systems and possess low-lying LUMO
energy levels and enhanced carrier mobilities. Further, because of
their good molecular planarity and their capacity to be easily
modified, the introduction of these fused-ring donor motifs into
150 mL ethanol, 30 mL water, 60 mL glacial acetic acid and 5 mL
3 M HCl. After refluxing for an additional 6 h and then cooling to
room temperature, the mixture was filtered and washed three
times with ethanol. The solvent was then removed by evaporation
and water was added. The mixture was then extracted with diethyl
0 0 0 0
3,2-b:2 ,3 -d]silole (DTS) and dithieno[3,2-b:2 ,3 -d]pyrrole (DTP)
4
ether and then dried over anhydrous MgSO . The solvent was
various
p
-conjugated polymeric and molecular materials is desir-
removed by evaporation, and the crude product was recrystallized
in hexane to afford colorless crystals (14.54 g, 86.3%). H NMR
1
able for providing high carrier mobilities, enhanced fluorescence
and reduced band gaps [16e18].
(CDCl
3
),
d
(ppm): 7.41 (d, J ¼ 5.5 Hz, 2H), 7.09 (d, J ¼ 5.0 Hz, 2H).
0 0 00
2
,2 :6 ,2 -Terpyridine and its derivatives are well-studied,
0
0
though they remain fascinating because of their outstanding
favorable geometry and because they can be used in metal-
lomacrocycles [19], terpyridine-ruthenium(II) complexes for their
photovoltaic performance [20], and supramolecular materials and
chemistry [21e23]. Interest in supramolecular polymers (SP), in
which the monomeric building blocks are held together via non-
covalent interactions, such as hydrogen bonding, metal coordina-
2.1.3. N-dodecyldithieno[3,2-b:2 ,3 -d]pyrrole (3)
t
A mixture of 2 (7.50 g, 23.3 mmol), NaO Bu (5.38 g, 56.0 mmol)
and BINAP (1.45 g, 2.2 mmol) in 65 mL dry toluene was purged with
N for 30 min. A catalytic amount of Pd dba and dodecylamine
2 2 3
(4.54 g, 24.5 mmol) were added to the above mixture and the re-
action mixture was stirred and heated under reflux overnight. After
cooling to room temperature, water was added to the mixture. The
mixture was extracted with diethyl ether and then dried over
tion, electrostatic interactions, hydrophobic interactions and
pep
interactions, has been stimulated because of the vast of progresses
in modern supramolecular chemistry [24]. The so-called metallo-
supramolecular polymers, which are based on metal-ligand coor-
dination, have recently made rapid progress in supramolecular
systems and materials [25,26]. The introduction of metal ions into
the backbones of the supramolecular polymers results in some very
interesting photophysical and electrochemical properties. At the
same time, pyridine rings, especially terpyridine, can be used as the
electron-withdrawing units, and monomeric building blocks
4
anhydrous MgSO . The solvent was removed by evaporation. The
crude product was purified by silica gel column chromatography
1
(hexane) to give the product as a light yellow oil (6.69 g, 82.6%). H
NMR (CDCl
3
),
d
(ppm): 7.13 (d, J ¼ 5.0 Hz, 2H), 7.00 (d, J ¼ 5.5 Hz,
2H), 4.20 (t, J ¼ 7.0 Hz, 2H), 1.86 (m, 2H), 1.30e1.24 (m, 18H), 0.88 (t,
J ¼ 6.5 Hz, 3H).
0
0
2.1.4. 2,6-Dibromo-N-dodecyldithieno[3,2-b:2 ,3 -d]pyrrole (4)
To a solution of 3 (3.15 g, 9.1 mmol) in 300 mL THF was added
0
0
00
ꢀ
incorporated with 2,2 :6 ,2 -terpyridine can be used to generate
D-A -conjugated organic/polymers materials [27,28].
Based on the above considerations, we report herein the details
of the synthesis of novel building blocks based on -conjugated
,2 :6 ,2 -terpyridine. Using Suzuki coupling reactions with Pd-
NBS (3.23 g, 18.1 mmol) at 0 C. Water was added after the solution
p
was stirred for 2 h. The mixture was extracted with CH
over anhydrous MgSO , and the solvent was removed under
reduced pressure. The crude product was recrystallized from
2 2
Cl , dried
4
p
0
0
00
1
2
CH
NMR (CDCl
2H), 1.28e1.24 (m, 18H), 0.88 (t, J ¼ 7.0 Hz, 3H).
2
Cl
2
/methanol to give light yellow crystals (3.71 g, 81.2%).
H
0
0
00
catalysts, the electron-acceptor
p
-conjugated 2,2 :6 ,2 -terpyr-
3
), d
(ppm): 6.91 (s, 2H), 4.08 (t, J ¼ 7.0 Hz, 2H), 1.80 (m,
idine was coupled with the electron-donor moieties carbazole, DTS
and DTP, which have good molecular planarity because of their
fused-rings, to synthesize the monomeric building blocks CzTPY,
SiTPYand NTPY, respectively (Scheme 1). Directed by the transition
0
0
2.1.5. 3,3 -dihexylsilylene-2,2 -bithiophene (5)
2.2 M n-BuLi in hexane (7.32 mL, 16.2 mmol) was added drop-
metal ion Zn2
þ
,
three new donoreacceptor metallo-
wise to a solution of 2 (2.49 g, 7.7 mmol) in anhydrous THF (55 mL)
ꢀ
supramolecular polymers were synthesized via self-assembly
polymerization under moderate conditions (Scheme 2). The ef-
fects of the D-A molecular structures and the transition metal ions
on the photophysical, electrochemical properties and the energy
gaps of the resulting metallo-polymers were fully investigated in
this paper.
under vigorous stirring at ꢁ78 C. The mixture was then stirred
ꢀ
at ꢁ78 C for 1 h. Then, a solution of dichlorodihexylsilane (2.50 mL,
8.1 mmol) in THF (100 mL) was added dropwise. The reaction
ꢀ
mixture was stirred at ꢁ78 C for an additional 5 h. The mixture
was allowed to warm to room temperature overnight with stirring.
The reaction mixture was quenched and a saturated aqueous NH
solution was added. The mixture was extracted with diethyl ether
and then dried over MgSO . The solvent was removed by evapo-
4
Cl
2
. Experimental section
4
ration, and the crude product was purified by silica gel column
2
.1. Synthesis of the monomeric building blocks and metallo-
chromatography (hexane) to yield a light yellow liquid (1.84 g,
1
supramolecular polymers
66.6%). H NMR (CDCl
J ¼ 4.5 Hz, 2H), 1.41e0.85 (m, 26H).
3
),
d
(ppm): 7.19 (d, J ¼ 4.5 Hz, 2H), 7.05 (d,
0
0
0
2.1.1. 3,3 ,5,5 -tetrabromo-2,2 -bithiophene (1)
0
0
0
0
To a solution of 2,2 -bithiophene (2.78 g, 16.7 mmol) in the
2.1.6. 5,5 -dibromo-3,3 -dihexylsilylene-2,2 -bithiophene (6)
mixed solvent of glacial acetic acid (20 mL) and CHCl
3
(23 mL) at
To a solution of 5 (0.26 g, 0.7 mmol) in 10 mL DMF was added
NBS (0.28 g, 1.6 mmol) in one portion. The mixture was stirred at
room temperature for 10 min, and then water was added. The
mixture was extracted with diethyl ether. The combined organic
ꢀ
0
C was added dropwise bromine (9.8 g, 61.3 mmol) in 20 mL
3
CHCl . The mixture was stirred at room temperature overnight and
then heated under reflux for 24 h. After cooling to room tempera-
ture, 50 mL of 10% KOH aqueous solution was added, followed by
4
phase was washed with water and dried over MgSO . The solvent
extraction with CHCl
MgSO and the solvent was removed by evaporation. After
recrystallization from ethanol, colorless crystals were obtained
3
. The organic layer was dried over anhydrous
was removed, and the product was purified by silica gel column
chromatography (hexane) to afford a green liquid (0.31 g, 89.1%). H
NMR (CDCl ), d (ppm): 6.99 (s, 2H), 1.34e0.88 (m, 26H).
3
1
4
1
(
3
7.50 g, 93%). H NMR (CDCl ), d (ppm): 7.04 (s, 2H).
2
.1.7. 2,7-Dibromo-N-octylcarbazole (7)
To a solution of 2,7-dibromocarbazole (1.63 g, 50.0 mmol) in
0
0
2
.1.2. 3,3 -dibromo-2,2 -bithiophene (2)
Compound 1 (25.00 g, 51.8 mmol) was added to a refluxing
dispersion of zinc powder (13.00 g, 0.3 mol) in a mixing solution of
10 mL DMSO were added 1-bromooctane (1.45 g, 75.0 mmol) and
5 mL of a 50% NaOH solution. The mixture was stirred at room