Macromolecules, Vol. 38, No. 22, 2005
Colorimetrically Reversibe Polydiacetylene Supramolecules 9375
and the N-hydroxysuccinimide ester of 10,12-pentacosadiynoic
acid (PCDA-NHS 16) were prepared as described in the
literature.48 The diacetylenic monomers PCDA-mBzA 1, PCDA-
aniline 8, PCDA-oBzA 9, and PCDA-pBzA 10 were previously
reported.46
ECDA-NPA 12: mp 231 °C. 1H NMR (300 MHz, DMSO-
d6): δ ) 0.81 (t, 3H), 1.22-1.40 (m, 22H), 1.81 (t, 2H), 2.08 (s,
1H), 2.24 (t, 2H), 2.39 (t, 2H), 7.65 (d, 2H), 7.87(q, 2H), 8.03
(d, 1H), 8.39 (s, 1H), 8.49 (s, 1H), 10.29 (s, 1H). 13C NMR (75
MHz, DMSO-d6): δ ) 13.89, 14.06, 18.09, 18.33, 22.18, 23.67,
27.77, 28.30, 28.52, 28.83, 29.13, 31.38, 35.24, 65.34, 65.85,
77.27, 78.14, 114.42, 120.09, 125.35, 126.46, 127.52, 128.63,
130.23, 135.79, 139.00, 167.54, 171.01.
Preparation of Diacetylene Monomers. The diacetylene
monomers investigated in this study were prepared by cou-
pling either the acid chlorides (for the preparation of 2, 5, 6,
7, 11, 12, and 13) or N-hydroxysuccininic esters (for the
preparation of 3 and 4) of PCDA 14, HCDA 17, ECDA 18, or
HDCDA 19 with corresponding amines or alcohol. A typical
procedure for the preparation of PCDA-mCPE 2 is as follows.
To a solution containing 1.39 g (3.70 mmol) of 10,12-penta-
cosadiynoic acid in 20 mL of methylene chloride was added
dropwise 0.94 g (7.4 mmol) of oxalyl chloride at room temper-
ature. The resulting solution was stirred at room temperature
for 1 h. To the solution was added a catalytic amount (one
drop) of DMF and stirred for an additional hour. After
concentrating in vacuo, the residue was redissolved in 15 mL
of methylene chloride. The resulting solution was added
dropwise to the solution containing 0.66 g (4.81 mmol) of
3-aminobenzoic acid in 15 mL of THF. The resuting mixture
was allowed to stir for overnight at room temperature. The
solvent was removed in vacuo, and the residue was purified
by silica gel column chromatography (4:1 chloroform: metha-
nol) to give 0.48 g (26%) of the desired diacetylene monomer
PCDA-mCPE 2 as a white solid. Other diacetylene monomers
were also prepared by employing similar procedures. Spectro-
scopic data for the monomers are as follows:
1
HDCDA-NPA 13: mp 242 °C. H NMR (300 MHz, DMSO-
d6): δ ) 0.82 (t, 3H), 1.21-1.42 (m, 17H), 2.26 (t, 2H), 2.63 (s,
4H), 7.66 (d, 1H), 7.89 (q, 2H), 8.04 (d,1H), 8.39 (s, 1H), 8.51
(s, 1H), 10.35 (s, 1H). 13C NMR (300 MHz, DMSO-d6): δ )
13.95, 14.69, 18.29, 22.16, 27.69, 28.01, 28.45, 28.69, 28.96,
31.33, 34.88, 65.28, 65.53, 77.00, 78.47, 114.54, 119.00, 123.17,
126.56, 127.62, 128.71, 130.27, 135.76, 138.79, 167.53, 169.75.
General Procedures for Liposome Formation. 10,12-
Pentacosadiynoic acid (PCDA) was dissolved in chloroform,
and the organic solvent was removed by purging with N2 to
generate a thin lipid film on the glass surface. A buffer solution
(HEPES, 5 mM, pH ) 8.0) or deionized water was added to
yield a total PCDA lipid concentration of 1 mM. The samples
were then heated at 80 °C for 15 min and sonicated for 15
min. The resulting solution was filtered through a 0.8 µm filter,
and the filtrate was cooled at 4 °C for 12 h. Polymerization
was carried out at room temperature by irradiating the
solutions with 254 nm UV light (1 mW/cm2).
Preparation of Langmuir-Schaefer (LS) Films. An
aliquot of the solution containing 1 mM of a PCDA derivative
in organic solvent (CHCl3 or DMSO for chloroform-insoluble
diacetylenes) was spread onto the air/water interface of a KSV
Langmuir trough containing deionized (DI) water (the initial
resistivity ) 18 MΩ‚cm, Milli-Q water purifier) as the sub-
phase. The substances were equilibrated at 25 °C for 20 min
to allow solvent to be removed from the interface. The lipid
film was overcompressed at a surface pressure of 30 mN/m to
form multilayers and polymerized by irradiation with the 254
nm UV light (1 mW/cm2) for 45 s to give blue films. By the
horizontal-touch Langmuir-Schaefer (LS) method, the pre-
pared films were then transferred to glass slides previously
hydrophobized with self-assembled octadecanoic triethoxysi-
lane molecules and to CaF2 substrates for further FTIR
analyses.
Colorimetric Responses upon Thermal Stimuli. For
experiments imposing thermal stimulus, heating from and
cooling to room temperature were done with a heating cell.
The instrument (HP 8453) was temperature-controlled, and
the actual sample temperature was monitored. The visible
spectra of the polymer vesicle solutions and LS films at
different temperatures were acquired with a UV-vis spectro-
photometer.
FTIR Analyses. An FTIR spectrometer (Perkin-Elmer
Spectrum GX1) was used to acquire transmission and 10° near-
normal external reflection spectra for the LS films deposited
on glass slides. The MCT detector was cooled with liquid
nitrogen, and 256 scans with a resolution of 4 cm-1 were
accumulated to give reasonable signal-to-noise ratios. Nonpo-
larized infrared beam was used. The in-situ external reflection
spectra at 10° from the surface normal were obtained after
the samples maintained at desired temperatures for 30 min
by using a house-built temperature-controlled heating element
designed to fit in the sample chamber of the spectrometer.
PCDA-mCPE 2: mp 71 °C. 1H NMR (300 MHz, CDCl3):
δ ) 0.88 (t, 3H), 1.20-1.80 (m, 36H), 2.22 (t, 4H), 2.35 (t, 2H),
7.07-7.55 (m, 5H), 7.18 (brs, 1H). 13C NMR (75 MHz, DMSO-
d6): δ ) 13.86, 18.39, 22.21, 24.27, 27.86, 28.30, 28.44, 28.87,
29.16, 31.43, 33.45, 65.38, 77.495, 122.60, 126.19, 126.59,
129.68, 132.34, 150.46, 166.49, 171.55.
PCDA-ABA 3: mp 80 °C. 1H NMR (300 MHz, CDCl3): δ )
0.85 (t, 3H), 1.20-1.62 (m, 36H), 1.86 (q, 1H), 2.18 (t, 1H),
2.21-2.38 (m, 6H), 2.24 (t, 1H), 2.42 (t, 1H), 3.35 (q, 1H), 5.72
(s, 1H), 7.50 (t, 1H), 7.82 (s, 1H), 7.98 (d, 1H), 7.18 (brs, 1H).
13C NMR (75 MHz, DMSO-d6): δ ) 14.02, 18.29, 22.14, 24.65,
27.72, 28.41, 29.04, 31.05, 31.34, 35.38, 40.33, 65.35, 77.92,
172.02, 174.27.
PCDA-Gly 4: mp 96 °C. 1H NMR (300 MHz, DMSO-d6):
δ ) 0.86 (t, 3H), 1.20-1.62 (m, 28H), 2.11 (t, 2H), 2.28 (t, 4H),
3.69 (t, 3H), 8.08 (s, 1H). 13C NMR (75 MHz, DMSO-d6): δ )
18.35, 22.20, 25.22, 27.85, 28.29, 28.52, 28.65, 28.83. 29.13,
31.41, 35.07, 40.53, 65.39, 77.82, 171.52, 172.54.
HCDA-mBzA 5: mp 164 °C. 1H NMR (300 MHz, DMSO-
d6): δ ) 0.83 (t, 3H), 1.20-1.65 (m, 36H), 2.31 (t, 6H), 7.41 (t,
1H), 7.60 (d, 1H), 7.81 (d, 1H), 8.23 (s, 1H), 10.07 (s, 1H). 13C
NMR (75 MHz, DMSO-d6): δ ) 14.67, 19.02, 22.85, 25.64,
28.46, 28.84, 29.19, 29.45, 29.67, 32.05, 37.06, 66.09, 78.52,
78.60, 120.49, 123.71, 124.44, 129.55, 132.08, 140.25, 167.98,
172.13.
ECDA-mBzA 6: mp 202 °C. 1H NMR (300 MHz, DMSO-
d6): δ ) 0.85 (t, 3H), 1.24-1.45 (m, 22H), 1.77 (m, 2H), 2.25-
2.42 (m, 6H), 7.38 (t, 1H), 7.57 (d, 1H), 7.78 (d, 1H), 8.20 (s,
1H), 10.09 (s, 1H). 13C NMR (75 MHz, DMSO-d6): δ ) 13.95,
18.04, 18.30, 22.15, 23.65, 27.75, 28.25, 28.48, 28.78, 29.07,
31.35, 35.10, 65.32, 65.79, 77.28, 78.17, 119.84, 123.10, 123.82,
128.88, 131.24, 139.45, 167.21, 170.66.
1
HDCDA-mBzA 7: mp 71 °C. H NMR (300 MHz, DMSO-
Light Scattering Measurement. A Spectra-Physics argon
ion laser producing vertically polarized light of λ0 ) 488 nm
was used. The detector optics employed optical fibers coupled
to an ALV/SO-SIPD/DUAL detection unit that employed an
EMI PM-28B power supply and ALV/PM-PD preamplifier/
discriminator. The correlator was an ALV-5000/E/WIN mul-
tiple tau correlator with 288 exponentially spaced channels.
The sampling time of the correlator ranged from 10-6 to 130
s. The cylindrical scattering cell was located in a bath of index
matching solvent (decalin) that was maintained at room
temperature. The band-pass filter for 488 nm was used. Each
correlation function was gathered at five different angles from
θ ) 30° to 90°.
d6): δ ) 0.85 (t, 3H), 1.23-1.44 (m, 17H), 2.26 (t, 2H), 2.50-
2.60 (m, 4H), 7.40 (t, 1H), 7.59 (d, 1H), 7.78 (d, 1H), 8.20 (s,
1H), 10.15 (s, 1H). 13C NMR (75 MHz, DMSO-d6): δ ) 13.95,
14.65, 18.30, 22.16, 27.72, 28.25, 28.48, 28.74, 28.99, 31.35,
34.78, 65.25, 65.49, 76.90, 78.39, 119.81, 123.11, 124.01,
129.00, 131.30, 139.29, 167.18, 169.35.
PCDA-NPA 11: mp 215 °C. 1H NMR (300 MHz, DMSO-
d6): δ ) 0.84 (t, 3H), 1.22-1.42 (m, 37H), 2.26 (t, 4H), 2.37 (d,
2H), 7.60 (d, 1H), 7.90 (q, 1H), 8.04 (d, 1H), 8.40 (s, 1H), 8.49
(s, 1H), 10.22 (s, 1H). 13C NMR (75 MHz, DMSO-d6): δ 13.89,
18.07, 18.98, 22.76-37.25, 66.09, 78.72, 114.50, 121.09, 123.31,
125.45, 128.51, 129.53, 130.84, 135.70, 139.76, 168.84, 172.34.