Metal Ion-Recognition-Induced Conjugated Polymers
J. Am. Chem. Soc., Vol. 119, No. 1, 1997 21
2,5-Bis(decyloxy)-4-[[5′-(bromomethyl)-2,2′-bipyridin-5-yl]vinyl]-
benzaldehyde (13a) and 2,5-Bis(decyloxy)-1,4-bis[[5′-(bromo-
methyl)-2,2′-bipyridin-5-yl]vinyl]benzene (13b). To a solution of
compounds 12 (0.60 g, 1.0 mmol) and 8 (0.45 g, 1.0 mmol) in
methylene chloride (30 mL) was added lithium ethoxide (1.0 mL, 1.0
M solution in THF) dropwise via a syringe at room temperature. The
resulting solution was allowed to stir at room temperature for 3 h before
being poured into water. The organic phase was separated and washed
with water. Solvent was then taken off under reduced pressure. The
residue, dissolved in small amount of chloroform, was loaded onto the
top of a silica gel column. Elution with 0-0.25% MeOH in CHCl3
thus gave rise to product 13a as a yellow solid (0.34 g, 49.1% yield)
and product 13b as a brown solid (0.11 g, 11.3% yield), respectively.
Further Z- to E-isomerizations were achieved by heating solution of
the respective compound in toluene in the presence of TsOH overnight.
For 13a: 1H NMR (CDCl3) δ (ppm) 0.89 (m, 6H, CH3), 1.26 (m, 12H,
OCH2CH2CH2(CH2)6CH3), 1.51 (m, 4H, OCH2CH2CH2(CH2)6CH3),
1.87 (quintet, 4H, J′ ) 6.42 Hz, J′′ ) 6.43 Hz, OCH2CH2CH2(CH2)6-
CH3), 4.06 (t, J ) 6.43 Hz, 2H, OCH2CH2CH2(CH2)6CH3), 4.13 (t, J
) 6.43 Hz, 2H, OCH2CH2CH2(CH2)6CH3), 4.55 (s, 2H, CH2Br), 7.20
(s, 1H, phenyl-H), 7.33 (d, J ) 15.85 Hz, vinyl-H), 7.35 (s, 1H, phenyl-
H), 7.58 (d, J ) 16.71 Hz, vinyl-H), 7.88 (dd, J′ ) 8.47 Hz, J′′ ) 2.14
Hz, 1H, pyridyl H4), 8.04 (dd, J′ ) 8.57 Hz, J′′ ) 2.14 Hz, 1H, pyridyl
H4′), 8.45 (dd, J′ ) 8.04 Hz, J′′ ) 2.57 Hz, 2H, pyridyl H3 and H3′),
8.71 (s, 1H, pyridyl H6), 8.82 (s, 1H, pyridyl H6′), 10.47 (s, 1H, CHO).
Mass spectrum m/e calcd for C40H55BrN2O3: 691.8, found 691.7. For
13b: 1H NMR (CDCl3) δ (ppm) 0.87 (m, 6H, CH3), 1.01-1.85 (m,
32H, OCH2(CH2)8CH3), 4.00 (t, J ) 5.57 Hz, 4H, OCH2(CH2)8CH3),
4.55 (s, 4H, CH2Br), 7.16 (s, 2H, phenyl-H), 7.24 (d, J ) 16.77 Hz,
vinyl-H), 7.66 (d, 2H, J ) 16.27 Hz, vinyl-H), 7.87 (d, 2H, J ) 7.71
Hz, pyridyl H4 and H4′′), 7.88 (d, J ) 7.38 Hz, pyridyl H4′ and H4′′′),
8.43 (d, J ) 8.57 Hz, pyridyl H3, H3′, H3′′, and H3′′′), 8.69 (s, 2H,
pyridyl H6 and H6′′), 8.80 (s, 2H, pyridyl H6′′ and H6′′′). Mass
spectrum m/e calcd for C52H62Br2N4O2: 934.9, found 934.4.
(s, 2H, pyridyl H6′′ and H6′′′). Mass spectrum m/e calcd for
C
Polymer 1. Route A: A suspension of 13b (0.108 g, 0.115 mmol)
108H156N4O6 (M+ - 2Br): 1606.5, found 1606.3.
and triphenylphosphine (0.100 g, 0.380 mmol) in DMF (25 mL) was
heated at reflux for 4 h before letting it cool. To this clear solution
was added lithium ethoxide (230 µL, 1.0 M in THF) all at once.
Subsequent addition of compound 8 to this deep red solution did not
result in a homogenous solution. However, compound 8 (0.051 g, 0.115
mmol) started to dissolve and the red color began to fade gradually
when heating the mixture near 100 °C. Soon after the clear solution
was obtained, a yellow-brown solid precipitated out. Heating was
continued for 2 h, and then the reaction mixture was allowed to cool
down to room temperature. The solid was collected by suction filtration
and dried under vacuum (55 mg, 40.2%). Extraction with a micro-
Soxhlet extractor using ethyl acetate as the solvent for 24 h (until the
extract was colorless) then afforded polymer 1 with an average
molecular weight of 5800 based on polystyrene standard by GPC.
Polymer 1. Route B: A solution of 13a (0.34 g, 0.49 mmol) and
triphenylphosphine (0.144 g, 0.55 mmol) in toluene (20 mL) was heated
at reflux for 4 h. The solvent was then removed on a rotary evaporator
under reduced pressure. To a solution of the resulting residue in
methylene chloride was added lithium ethoxide via a syringe dropwise.
The reaction mixture was allowed to stir at room temperature for 48 h
before being poured into methanol (500 mL). The precipitates were
filtered by suction and subsequently dissolved in CHCl3 and washed
with water. Removal of solvent under reduced pressure afforded
polymer 1 as a dark brown solid (0.26 g, 89.2% yield). Further
extraction of the obtained polymer with a micro-Soxhlet extractor using
ethyl acetate as the solvent until the extract was colorless gave a polymer
with Mn ) 6400 by GPC. 1H NMR (CDCl3) δ (ppm) 0.89 (br, OCH2-
CH2CH2(CH2)6CH3), 1.28 (br, OCH2CH2CH2(CH2)6CH3), 1.58 (br,
OCH2CH2CH2(CH2)6CH3), 1.92 (br, OCH2CH2CH2(CH2)6CH3), 4.11
(br, OCH2CH2CH2(CH2)6CH3), 7.17 (br, phenyl-H), 7.49-7.70 (m,
vinyl-H), 7.98 (br, pyridyl H4), 8.44 (br, pyridyl H3), 8.80 (br, pyridyl
H6).
Compounds 14a and 14b. To a solution of compounds 12 (0.237
g, 0.39 mmol) and 10 (0.500 g, 0.39 mmol) in methylene chloride (50
mL) was added lithium ethoxide (0.4 mL, 1.0 M solution in THF)
dropwise via a syringe at room temperature. The resulting solution
was allowed to stir at room temperature for 24 h before being poured
into methanol. The orange precipitate was filtered off by suction. The
solid was dissolved in small amount of chloroform and loaded onto
the top of a silica gel column. Elution with 0-0.25% MeOH in CHCl3
thus gave rise to product 14a as a brown solid (0.15 g, 25.3% yield)
and product 14b as a dark brown solid (0.24 g, 34.9% yield),
respectively. Further Z- to E-isomerizations were achieved by heating
solutions of the respective compounds in toluene in the presence of
TsOH overnight. For 14a: 1H NMR (CDCl3) δ (ppm) 0.87 (m, 18H,
OCH2CH2CH2(CH2)6CH3), 1.26 (m, 72H, OCH2CH2CH2(CH2)6CH3),
1.54 (m, 12H, OCH2CH2CH2(CH2)6CH3), 1.88 (m, 12H, OCH2CH2-
CH2(CH2)6CH3), 4.07 (m, 12H, OCH2CH2CH2(CH2)6CH3), 4.55 (s, 2H,
CH2Br), 7.15 (s, 2H, phenyl H3′′ and H6′′), 7.18 (d, J ) 14.5 Hz, 2H,
vinyl-H), 7.21 (d, J ) 14.77 Hz, 2H, vinyl-H), 7.33 (s, 1H, phenyl
H6), 7.52 (s, 3H, phenyl H3, H3′, and H6′), 7.62 (d, J ) 16.52 Hz,
vinyl-H), 7.64 (d, J ) 16.49 Hz, vinyl-H), 7.87 (d, J ) 8.23 Hz, 1H,
pyridyl H4), 8.00 (d, J ) 8.35 Hz, 1H, pyridyl H4′), 8.42 (d, J ) 8.24
Hz, 1H, pyridyl H3), 8.43 (d, J ) 8.16 Hz, 1H, pyridyl H3′), 8.70 (s,
1H, pyridyl H6), 8.80 (s, 1H, pyridyl H6′), 10.45 (s, 1H, CHO). Mass
spectrum m/e calcd for C96H147N2O7 (M+ - Br): 1441.2, found 1441.5.
For 14b: 1H NMR (CDCl3) δ (ppm) 0.87 (m, 18H, OCH2CH2-
CH2(CH2)6CH3), 1.26 (m, 72H, OCH2CH2CH2(CH2)6CH3), 1.55 (m,
12H, OCH2CH2CH2(CH2)6CH3), 1.88 (m, 12H, OCH2CH2CH2(CH2)6-
CH3), 4.08 (m, 12H, OCH2CH2CH2(CH2)6CH3), 4.55 (s, 4H, CH2Br),
7.15-7.22 (m, 6H, phenyl H3, H6, H6′, H6′′ and vinyl-H), 7.26 (m,
2H, vinyl-H), 7.52 (m, 4H, phenyl H3′, H3′′, vinyl-H), 7.61 (d, J )
16.48 Hz, 2H, vinyl-H), 7.87 (d, J ) 8.20 Hz, 2H, pyridyl H4 and
H4′), 8.00 (d, J ) 6.59 Hz, 2H, pyridyl H4′′ and H4′′′), 8.41 (m, 1H,
pyridyl H3, H3′, H3′′, and H3′′′), 8.69 (s, 2H, pyridyl H6, H6′), 8.80
Polymer 2. A solution of compound 14a (0.15 g, 98.6 µmol) and
triphenylphosphine (50 mg, 190 µmol) in toluene (20 mL) was heated
at reflux for 4 h. After being cooling to room temperature, lithium
ethoxide (100 µL, 1.0 M in THF) was added to this solution dropwise.
The resulting solution was heated at reflux for an additional 48 h. The
product was precipitated out from methanol and collected by filtration.
This furnished polymer 2 as a dark brown solid (0.13 g, 92.6% yield).
Further extraction of the obtained polymer with a micro-Soxhlet
extractor using ethyl acetate as the solvent until the extract was colorless
gave a polymer with Mn ) 22000 by GPC. 1H NMR (CDCl3) δ (ppm)
0.87 (br, OCH2CH2CH2(CH2)6CH3), 1.28 (br, OCH2CH2CH2(CH2)6-
CH3), 1.56 (br, OCH2CH2CH2(CH2)6CH3), 1.90 (br, OCH2CH2CH2(CH2)6-
CH3), 4.09 (br, OCH2CH2CH2(CH2)6CH3), 7.15 (br, phenyl-H), 7.46-
7.75 (m, vinyl-H), 8.00 (br, pyridyl H4), 8.42 (br, pyridyl H3), 8.80
(br, pyridyl H6).
Polymer-Metal Complex Formation. Polymer-metal complex
solutions used for optical measurements in general were prepared from
a polymer solution (2 mL, 1.0 × 10-5 M in chloroform) and a metal
salt solution (0.1-0.2 mL, 1.0 × 10-3 M in methanol) at room
temperature. The polymer-lanthanide complexes were prepared the
same way as other transition and main group metal-based polymer
complexes except the solvents were evaporated off after mixing polymer
and metal ion together so that they were methanol-free once redissolved
in chloroform. Polymeric films were made by spin-coating solutions
of the polymers on glass plates.
Acknowledgment. This work was supported by the Office
of Computational and Technological Programs, Division of
Laboratory Technology Research, United States Department of
Energy under contract W-31-109-ENG-38.
JA962229D