Vesicle formation from an amphiphilic porphyrin derivative at the air-water interface

Article abstract of DOI:10.1002/asia.200900329

A tetraphenyl porphyrin derivative with two C₁₆ alkyl chains covalently bound to each of the four peripheral phenyl rings through ether linkages formed multilayer clusters or vesicles at the air-water surface. More interestingly, spherical vesicles were also formed when deposited on appropriate solid surfaces, and these vesicles were stable even in dry conditions. Various microscopic images of the cast film deposited on a mica surface confirmed closed-ended nanotube/nanorod-type formation with necking and bulging. These narrow tubes are proposed to be intermediates for the formation of vesicles by fission at either side of the bulge. Such vesicular formation is not common when either cast or Langmuir-Blodgett films were deposited on a solid surface.

Full text of DOI:10.1002/asia.200900329

FULL PAPERS
DOI: 10.1002/asia.200900329
Vesicle Formation from an Amphiphilic Porphyrin Derivative at the Air–
Water Interface
[
a]
[b]
[a]
Amrita Ghosh, Sipra Choudhury,* and Amitava Das*
Abstract: A tetraphenyl porphyrin de-
rivative with two C16 alkyl chains cova-
lently bound to each of the four pe-
ripheral phenyl rings through ether
linkages formed multilayer clusters or
vesicles at the air–water surface. More
interestingly, spherical vesicles were
also formed when deposited on appro-
priate solid surfaces, and these vesicles
were stable even in dry conditions. Var-
ious microscopic images of the cast
film deposited on a mica surface con-
firmed closed-ended nanotube/nano-
rod-type formation with necking and
bulging. These narrow tubes are pro-
posed to be intermediates for the for-
mation of vesicles by fission at either
side of the bulge. Such vesicular forma-
tion is not common when either cast or
Langmuir–Blodgett films were deposit-
ed on a solid surface.
Keywords: aggregation
·
Lang-
muir–Blodgett films · nanostruc-
tures · porphyrinoids · vesicles
Introduction
tive force that influences the aggregation phenomena and
thereby the generation of various structures. The hydropho-
bicity of the substituent on the peripheral phenyl rings is
also known to have a profound effect in ordering the aggre-
Porphyrins are structurally similar to chlorins and perform
important biological functions; for example, chlorophyll
plays an important role in photosynthesis. Porphyrin mole-
cules having long conjugated p-electron systems are also im-
portant because of their potential in applications such as gas
sensors, molecular electronics, photodynamic therapy, and
photosensitizers in photovoltaic cells. It has been argued
by many researchers that to develop better insight in the
natural light-harvesting process, it is essential to develop de-
sired porphyrinoid arrays using various noncovalent interac-
[7–9]
gates and nanostructured aggregates.
For certain tetraaryl
porphyrins and their metalloporphyrin derivatives, the rela-
tive ratios of different solvents determine the aggregation
phenomena, which eventually lead to the generation of vari-
[1]
[4]
ous nanostructures. Among various aggregated structures,
vesicles have gained significant importance in recent years,
as they represent simple model systems for biological mem-
branes and because of their utility in the storage, transport,
[2,3]
[10]
tions.
Because of the diverse packing, aggregation, and
and targeted release of drugs or DNA in living cells. In
self-assembly of aromatic macrocycles, porphyrin nanoag-
gregates assume various shapes, morphologies, and photo-
physical/photochemical properties, which are a function of
their unique structures and are important in many techno-
this context, porphyrin-based vesicles are also important for
developing efficient photodynamic therapeutic agents for
treating affected cells. There are examples of tetraaryl por-
phyrin derivatives with four dialkyl phosphocholine groups
that undergo spontaneous aggregation in water to form
[1,4–7]
logical applications.
In most cases, strong p–p stacking
[8,9b,11,12]
interactions are reported to be the most important interac-
spherical unilamellar vesicles.
However, examples of
vesicular formation from a single porphyrin molecule either
in a mixed solvent medium with a small amount of polar sol-
vent or at the air–water interface are not very common.
Herein, we report a newly synthesized porphyrin derivative
P (5,10,15,20-tetrakis(3,4-bishexadecyloxyphenyl)porphyrin;
Scheme 1) to demonstrate the effect of enhanced hydropho-
[
a] A. Ghosh, Dr. A. Das
Analytical Science Discipline
Central Salt & Marine Chemicals Research Institute
Bhavnagar 364002, Gujarat (India)
Fax : (+91)278-2567562
[13]
E-mail: amitava@csmcri.org
bicity on the aggregation behavior at the air–water interface
[
b] Dr. S. Choudhury
[14]
and generation of the higher ordered aggregates.
Com-
Chemistry Division
pound P was found to form spherical vesicles on the water
surface and was confirmed by AFM, HRTEM, and SEM.
Bhabha Atomic Research Center
Trombay, Mumbai 400085 (India)
E-mail: sipra@barc.gov.in
352
ꢀ 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Asian J. 2010, 5, 352 – 358

effect is reflected in the gradu-
al increase in area per mole-
cule. At neutral pH values, the
transfer ratio was found to
vary from 0.6 to 0.8 on a glass
substrate when P was deposit-
ed at a surface pressure of
ꢀ
1
3
0 mNm .
UV/Vis absorption spectra
of P in chloroform solution
showed an intense Soret (B)
Scheme 1. Synthesis of P.
Results and Discussion
Compound P was synthesized following a three-step proce-
dure (Scheme 1). Analytical and spectroscopic data record-
ed for P confirmed the purity of the isolated compound.
Surface pressure–area (P–A) isotherms at room tempera-
ture (258C) for porphyrin amphiphiles at the air–water in-
terface were recorded (Figure 1a). For comparison, we have
also shown the P–A isotherm for the related porphyrin de-
[4]
rivative (P1) with four ether linkages. The mean molecular
areas of amphiphiles were obtained by extrapolating the
first vertical region of the isotherms to determine the areas
at zero surface pressure, which corresponds to the hypothet-
ical state of an uncompressed close-packed layer in which
the molecules at the interface begin to interact with each
other.
2
The area per molecule for P was found to be 80 ꢁ , which
[4]
is larger than that of P1 with four ether linkages. A closer
look at the structural variation in P revealed that orthogonal
orientation of the peripheral aryl ring with additional long
chains in its meta positions would contribute to an ineffi-
cient packing of the P molecules compared with those in P1
and hence is responsible for this effect. A similar argument
[16]
was offered earlier for related porphyrin derivatives. The
effect of variation of the pH value of the subphase on the
Langmuir–Blodgett (LB) film formation is shown in Fig-
Figure 1. a) Surface pressure–area isotherms of porphyrin derivatives (P
and P1) on water at 258C. b) Surface pressure–area isotherms for P at
subphase pH 6 (black, A), pH 4 (gray, B), and pH 2 (light gray, C) on
water at 258C.
ACHTUNGTRENNUNGu re 1b. For P, a detectable change (ca. 30%) in area per
molecule with decrease in pH is evident. At lower subphase
pH values, a positive charge on the protonated porphyrin
ring is expected to lower the possibility of aggregation be-
cause of repulsion of the porphyrin backbone, and this
band at around 426 nm and weaker Q bands in the region
5
00–670 nm (Figure 2). These bands could be assigned to al-
lowed and quasi-allowed p–p* transitions, respectively. The
positions and intensities of B and Q bands are known to be
[17]
affected by aggregation (J and H aggregates). This effect
is more prominent for the B band and is typically accompa-
nied by band splitting, hypochromicity, and broadening. In
general, absorption spectra of the LB films for P deposited
on quartz showed a distinct red shift (438 nm) relative to
that in the solution phase.
[14b,18,19]
According to the molecular exciton model,
a red
shift of an absorption band suggests either an in-line align-
ment of the transition dipole moments in porphyrin deriva-
tives or coplanarly inclined transition dipoles (J aggrega-
Chem. Asian J. 2010, 5, 352 – 358
ꢀ 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemasianj.org
353

A. Das et al.
FULL PAPERS
Figure 2. UV/Vis spectra of P in chloroform (black) and in LB films
(
gray). Intensity is normalized to the peak maxima.
tion), in which the angle between the center-to-center
vector and the transition moment is less than 54.78. Porphy-
rin molecules in J aggregates stack head-to-tail, causing a
red shift. A relatively smaller red shift for P relative to
those for well defined J-aggregated porphyrin mole-
[14b,18,19]
cules
suggests the presence of loose J-aggregated
structures and also accounts for the higher full width at half
maxima of the respective Soret bands. A similar model was
suggested to explain the spectroscopic behavior of cyanine
[14b,18]
dyes.
The lesser extent of red shift for P indicates a
weaker interaction between the porphyrin rings in the LB
film.
An AFM image recorded for a monolayer of LB film of
P, deposited on mica, revealed spherical vesicle formation
(
Figure 3) at the air–water interface. Porphyrin derivatives,
like other amphiphilic molecules, either self-assemble into a
lamellar membrane or form vesicles through destabilization
of the lamellar phase; however, the mechanism of bilayer
destabilization has not been clearly elucidated. Only a few
reports on vesicle formation using porphyrin derivatives are
[9,11–13,20]
available.
In the present study, the diameters of the vesicles ob-
served in AFM images were in the range 100–700 nm (aver-
age diameter approximately 500 nm), and the heights of
these vesicles were in the range 10–30 nm (average height
approximately 25 nm) (Figure 3c). These vesicles were
found to be stable even in the dry state on the mica surface
for almost 1 year. The dimensions of these spherical vesicles,
observed by AFM, were similar to those visualized by TEM
and SEM. Examples of such vesicular formation for porphy-
rin derivative are rare for LB films deposited on a solid sur-
face. HRTEM images recorded with a monolayer of LB film
of P, deposited on carbon-coated Cu grid, are shown in
Figure 4. Figure 4b shows one large (ca. 482 nm diameter)
vesicle formed, for which the shell thickness could be mea-
sured.
Figure 3. AFM images of LB monolayer of P deposited on mica at
ꢀ
1
3
0 mNm pressure and 258C: a) two-dimensional image, b) three-dimen-
sional image, and c) cross-sectional analysis.
sults in destabilization of the lamellar phase, which causes
[21]
The average cell thickness was found to be around 60 nm.
This value is quite large relative to the single bilayer thick-
polydispersity of the vesicles in both size and lamellarity.
An approximate ratio for the average number of mole-
[20]
ness of P (ca. 11.15 nm) (Scheme 2a). This observation in-
dicates the multilamellar vesicle formation at the air–water
interface. Swelling, arising from hydration of the hydrophilic
group of the porphyrin bilayer at the air–water interface, re-
cules in the inner (n) and outer (n ) layers of these multila-
i
o
mellar vesicles may also be estimated from the average di-
ameter of the vesicles (500 nm), the thickness of the multila-
mellar vesicles (ca. 60 nm), and the area per molecule (as
354
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ꢀ 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Asian J. 2010, 5, 352 – 358

Vesicle Formation from an Amphiphilic Porphyrin Derivative
closed vesicle, which each have a different number of mole-
cules in them. A large density fluctuation causes an appreci-
able decrease in the bending rigidity of the membrane,
[22–24]
which is required for vesicular formation.
2
2
n ¼ 4pl =a and n ¼ 4pðl ꢀ dÞ =a
ð1Þ
0
i
HRTEM images of LB monolayers of P deposited on a
Cu grid at much lower pressure (Figure 5) presumably show
the intermediate structure in the vesicle formation process.
Figure 4. a) TEM image of LB monolayers of P deposited on carbon-
ꢀ1
coated Cu grid at 30 mNm pressure (magnification; 80 kVꢂ6000) and
b) HRTEM image of the vesicle formed in the at LB monolayers of P
(
Magnification; 100 kVꢂ20000).
Figure 5. HRTEM images of LB monolayers of P deposited on Cu grid
ꢀ1
at 11 mNm
.
The thermodynamic instability at the edges of the inter-
mediate structure presumably causes bending and leads to
vesicle formation. Such a phenomenon is not uncommon for
[24]
phospholipid-based vesicular formation.
Vesicle formation was also observed in SEM images of
the cast film (Figure 6). Cast films for P were obtained
through either evaporation of solutions in dichloromethane
Figure 6. a) SEM image of the cast film of P dissolved in CH
CH OH mixture (1:4 v/v) revealing the formation of individual spherical
vesicles; b) higher magnification SEM image of the vesicle formed.
2 2
Cl and
3
Scheme 2. Cartoon representation of the proposed orientation of a) the
bilayer structure and b) the shell wall of P as a multilamellar (n>1) ve-
sicular structure formed by self-assembly.
on mica or on carbon-coated Cu grids. AFM, HRTEM, and
SEM images were recorded for these cast films (Figure 7).
The AFM image clearly shows evidence of necking and
bulging in a tube or rod-type formation (Figure 7a).
determined from the P–A isotherm, Figure 1a) by using
[22]
Equation 1, in which l is the particle diameter of the vesi-
cle, d is the thickness of the bilayer membrane, and a is the
surface area per lipidic porphyrin molecule. A tentative
Formation of a bulge close to the end of the tube was also
evident in the TEM image (Figure 7b). This result further
corroborates our observations in the AFM images. Vesicles
are also evident in the SEM image (Figure 7c) of the cast
film of P, developed from a CH Cl /CH OH (1:4 v/v) solvent
value for no (3928571) and n (3042285) was calculated.
i
Therefore, the ratio (n /n) of the molecules in the outer to
0
i
inner layer is around 1.3. Bending arises from the difference
in the area of the inner and the outer monolayers of a
2
2
3
mixture. A closer look at the SEM and TEM images (Fig-
Chem. Asian J. 2010, 5, 352 – 358
ꢀ 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemasianj.org
355

A. Das et al.
FULL PAPERS
Conclusions
Hydrophobic porphyrin derivative P with eight ether linked
alkyl chains was found to form multilamellar vesicles at the
air–water interface. Vesicles with an average diameter of
about 500 nm were observed in LB films deposited on mica.
These vesicles were found to be stable in dry conditions for
about 1 year. TEM images for the cast film of P also con-
firmed the formation of closed-ended nanotubes with neck-
ing and bulging, which are proposed as intermediates for the
formation of vesicles by fission at either end of the bulge.
Experimental Section
Materials
All chemicals were obtained from commercial sources and used as re-
ceived, unless mentioned otherwise. Cetyl alcohol was obtained from
Merck (India) and 3,4-dihydroxybezaldehyde was obtained from Aldrich
Chemicals. Thionyl chloride, pyrrole, and propionic acid were obtained
from S.D. Fine Chemicals (India). Solvents used for reactions and various
other studies were of A.R. grade (Merck, India) and were used as re-
ceived. Pyrrole was distilled under reduced pressure prior to use. Thor-
oughly degassed milliQ water was used for studies as it was required.
Instrumentation and Methods
1
H NMR spectra were recorded on Bruker 200 MHz FT NMR (model:
Advance-DPX 200) spectrometer at room temperature (258C). The
chemical shifts (d) and coupling constants (J) are given in ppm and Hz,
respectively, unless mentioned otherwise. Tetramethylsilane (TMS) was
1
used as an internal standard for all H NMR studies. ESIMS measure-
Figure 7. a) AFM image of cast film on mica by evaporating 30 mL of
ꢀ
1
ments were carried out on a Waters QTof-Micro instrument. Microanaly-
ses (C, H, N) were performed using a Perkin–Elmer 4100 elemental ana-
lyzer. Infrared spectra were recorded as a KBr pellets using a Perkin–
Elmer Spectra GX 2000 spectrometer. UV/Vis spectra were obtained by
using either Shimadzu UV-3101 PC or Cary 500 Scan UV/Vis/NIR spec-
trometer. AFM studies were carried out under ambient conditions using
scanning probe microscope SPM Solver P47 in contact mode using rec-
1
mgmL
solution of P in dichloromethane on mica at 258C;
b) HRTEM image of cast film using similar solution on carbon-coated
Cu grid (magnification; 200 kVꢂ6000); (c) SEM image of the cast film of
P molecule dissolved in dichloromethane and methanol (1:4 v/v) mixture
revealing the formation of the individual spherical vesicle from the fis-
sion of the tubes or rods formed.
3 4
tangular cantilever of Si N . The absorption spectra of LB films were re-
corded on a Chemito UV 2600 spectrophotometer. The HRTEM images
were recorded using a Jeol JEM-2100 transmission electron microscope.
Scanning electron microscopy (SEM) images were recorded with a LEO
1430 VP instrument at an accelerating voltage of 15 kV.
ACHTUNGTRENNUNGu re 7a and 7b) tends to suggest the formation of the indi-
vidual spherical vesicle from the fission of the tubes or rods
formed. Both images reveal closed-ended nanotube type for-
mation with mean wall thickness of approximately 60 nm.
The bulges in the narrow tubes are proposed to be the inter-
mediate structure prior to the vesicle formation. Fission at
either end of the bulge could result in an individual vesi-
Langmuir–Blodgett Film and AFM Studies
The porphyrin derivative was dissolved in chloroform and the final con-
ꢀ1
centration of P in the solution was adjusted to around 1 mgmL . This
solution was allowed to spread on the water surface with a Hamilton mi-
crosyringe. A minimum waiting time of 20 min was allowed for complete
evaporation of solvent and equilibration of the molecules on the water
surface. Pressure area isotherm measurements were carried out by using
a computer-controlled KSV 5000 Langmuir double barrier Teflon trough.
Surface pressure was measured with platinum Wilhelmy plate microba-
[
25,26]
cle.
the efficient aggregation during the fast drying process of
Presumably, tubes or rods were formed owing to
[23,27]
the organic solvent on the substrate.
As discussed earli-
er for the LB film, vesicle formation was observed at the
air–water interface, whereas no formation of nanostructured
closed-ended tubes could be detected. This result tends to
suggest that an equilibrium reached with spreading of P at
the air–water interface leads to more stable and complete
ꢀ1
lance. The compression rate (the barrier speed) used was 5 mmmin . LB
films were transferred onto quartz, glass, freshly cleaved mica, and
carbon coated copper grids by using the conventional dipping method.
Monolayers deposited on mica surfaces were used only for AFM studies,
and monolayers deposited on carbon-coated copper grid were used for
HRTEM studies.
[22,28]
vesicle formation.
Thus, it is evident that P, with eight
long hydrocarbon chains, formed multilamellar vesicles. The
broadening of the absorption spectrum (Figure 2) of the LB
film of P was presumably a result of the disordered assem-
bly of the long chains owing to vesicular formation.
Synthesis
[15]
Hexadecyl chloride (1) was synthesized by a known procedure. Analyt-
ical data matched well with values reported earlier and with the proposed
structure for the compound.
356
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ꢀ 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Asian J. 2010, 5, 352 – 358

Vesicle Formation from an Amphiphilic Porphyrin Derivative
3
,4-bis(hexadecyloxy)benzaldehyde (2) was synthesized by following an
[2] a) Z. Wang, C. J. Medforth, J. A. Shelnutt, J. Am. Chem. Soc. 2004,
126, 15954; b) T. Hasobe, S. Fukuzumi, P. V. Kamat, J. Am. Chem.
Soc. 2005, 127, 11884.
[3] A. D. Schwab, D. E. Smith, C. S. Rich, E. R. Young, W. F. Smith,
J. C. de Paula, J. Phys. Chem. B 2003, 107, 11339.
[
4,15]
adapted procedure (Scheme 1):
instead of the reported 4-hexadecyloxybenzaldehyde. 3,4-dihydroxyben-
zaldehyde (2.0 g, 14.4 mmol) was dissolved in dry DMF (80 mL) in a
3,4-dihydroxybenzaldehyde was used
two-necked round-bottom flask.
grounded powder form was added, and the mixture was stirred for
5 min. Then compound 1 (7.4 g, 28.8 mmol), dissolved in dry DMF
2 3
K CO (4.0 g, 28.8 mmol) in finely
[4] A. Ghosh, T. Selvamani, D. A. Jose, A. Das, I. Mukhopadhyay, J.
Nanomater. 2007, DOI: 10.115/2007/47234.
1
(
(
20 mL), was added to the reaction mixture from a dropping funnel. KI
4.5 g, 28.8 mmol) was added to the reaction mixture, and finally the re-
[
[
[
[
5] J. S. Hu, Y. G. Guo, H. P. Liang, L. J. Wan, L. Jiang, J. Am. Chem.
Soc. 2005, 127, 17090.
6] Z. Wang, K. J. Ho, C. J. Medforth, J. A. Shelnutt, Adv. Mater. 2006,
action mixture was heated at reflux for 3 days under dinitrogen atmos-
phere. The solution was allowed to attain room temperature and then
kept refrigerated for 1 h. The mixture was filtered to remove a white pre-
cipitate of undesired potassium salts. The filtrate was then evaporated
under reduced pressure. The solid residue thus obtained was redissolved
1
8, 2557.
7] A. P. H. J. Schenning, F. B. G. Benneker, H. P. M. Geurts, X. Y. Liu,
R. J. M. Nolte, J. Am. Chem. Soc. 1996, 118, 8549.
8] D. M. Vriezema, J. Hoogboom, K. Velonia, K. Takazawa, P. C. M.
Christianen, J. C. Maan, A. E. Rowan, R. J. M. Nolte, Angew. Chem.
2 2
in CH Cl and any remaining inorganic impurities were removed by sol-
vent extraction into the aqueous phase. The organic layer was collected
and evaporated to yield crude product, which was further purified by
column chromatography with silica gel (100–200 mesh) as the stationary
2
003, 115, 727; Angew. Chem. Int. Ed. 2003, 42, 703.
[
9] a) G. Li, W. Fudickar, M. Skupin, A. Klyszcz, C. Draeger, M. Lauer,
J. H. Fuhrhop, Angew. Chem. 2002, 114, 1906; Angew. Chem. Int.
Ed. 2002, 41, 1828; b) J. H. van Esch, A. M. P. Peters, R. J. M. Nolte,
J. Chem. Soc. Chem. Commun. 1990, 638.
phase and CHCl
3
as the eluent. The first fraction was collected and
evaporated. Yield: 3.75 g (45%); FTIR (KBr): n˜ =2919, 1688, 1587, 1511,
1
7
(
ꢀ
1
1
134, 808 cm
.38(d, 1H, J=5.8 Hz, 2-phenyl), 7.37 (d, 1H, J=5.8 Hz, 3-phenyl), 6.96
), 1.2 (b, 60H, ali-
2 2
; H NMR (200 MHz, CD Cl ): d=9.8 (s, 1H, -CHO),
[
10] a) H. Ringsdorf, B. Schlarb, J. Venzmer, Angew. Chem. 1988, 100,
17; Angew. Chem. Int. Ed. Engl. 1988, 27, 113; b) M. Ahlers, W.
1
d,1H, 8.2 Hz, 6-phenyl), 4.06 (t, 4H, J=6.4 Hz, -OCH
2
Muller, A. Reichert, H. Ringsdorf, J. Venzmer, Angew. Chem. 1990,
102, 1310; Angew. Chem. Int. Ed. Engl. 1990, 29, 1269; c) F. M.
Menger, K. Gabrielson, Angew. Chem. 1995, 107, 2260; Angew.
Chem. Int. Ed. Engl. 1995, 34, 2091; d) C. Paleos, D. Tsiourvas, Top.
Curr. Chem. 2003, 227, 1; e) A. Bonincontro, M. Falivene, C. L.
Mesa, G. Risuleo, M. R. PeÇa, Langmuir 2008, 24, 1973; f) G. Batta-
glia, A. J. Ryan, Nat. Mater. 2005, 4, 869.
+
3
phatic chain), 0.87 ppm (t, 6H, J=5.8 Hz, -CH ); ESIMS (m/z): 587 (M ,
+
+
ca. 17%); 610 [M +Na , 45%]; elemental analysis: calcd (%) for
: C 79.80, H 12.02; found: C 80.0, H 12.1.
,10,15,20-tetrakis(3,4-bishexadecyloxyphenyl)porphyrin (P): Freshly dis-
39 70 3
C H O
5
tilled pyrrole (0.15 mL, 2.3 mmol) was slowly added under stirring to a
solution of 2 (1.5 g, 2.5 mmol) in refluxing propionic acid (50 mL) under
inert atmosphere. Refluxing was continued for 4 h, and then the reaction
mixture was allowed to cool to room temperature. The precipitate ob-
tained was collected by filtration, washed with hot water, and air-dried.
[
11] a) E. Tsuchida, T. Komatsu, K. Arai, K. Yamada, H. Nishide, C.
Bottcher, J. H. Fuhrhop, J. Chem. Soc. Chem. Commun. 1995, 1063;
b) E. Tsuchida, T. Komatsu, K. Arai, H. Nishide, J. Chem. Soc.
Chem. Commun. 1993, 730; c) A. Kotiaho, R. M. Lahtinen, N. V.
Tkachenko, A. Efimov, A. Kira, H. Imahori, H. Lemmetyinen,
Langmuir 2007, 23, 13117; d) J. Spadavecchia, G. Ciccarella, T.
Stomeo, R. Rella, S. Capone, P. Siciliano, Chem. Mater. 2004, 16,
2 2
The crude product (2.2 g) was dissolved in CH Cl and 2,3-dichloro-5,6-
dicyanobenzoquinone (DDQ; 0.06 g) dissolved in toluene (300 mL) was
added. The reaction mixture was allowed to reflux for 3 h and then
cooled to room temperature. The reaction product was dried under
vacuum, and the crude solid was purified by column chromatography
using silica gel (100–200 mesh) as stationary phase and chloroform as
eluent. Yield: 0.59 mg (ca. 12%); FTIR (KBr): n˜ =2919, 1742, 1468,
2
083.
[
12] a) T. Komatsu, E. Tsuchida, C. Bottcher, D. Donner, C. Messer-
schmidt, U. Siggel, W. Stocker, J. P. Rabe, J. H. Fuhrhop, J. Am.
Chem. Soc. 1997, 119, 11660; b) I. O. Benitez, B. Bujoli, L. J. Camus,
C. M. Lee, F. Odobel, D. R. Talham, J. Am. Chem. Soc. 2002, 124,
ꢀ
1
1
1
7
135, 798 cm ; H NMR (200mHz, CD
.7 (d, 4H, J=8 Hz, 6-phenyl), 7.22 (d, 8H, J=5.6 Hz, 2,3-phenyl), 4.29
); 4.09 (t, 8H, J=5.2 Hz, -OCH ); 1.25 (b,
50H, aliphatic chain), 0.85 (t, 24H, J=5.2 Hz, -CH
), ꢀ2.75 ppm (b,
H, -NH); elemental analysis: calcd (%) for C172 : C 81.39,
2 2
Cl ): d=8.89 (s, 8H, b pyrroles),
(
t, 8H, J=6.2 Hz, -OCH
2
2
4
363; c) C. M. Dooling, O. Worsfold, T. H. Richardson, R. Tregon-
1
2
3
ning, M. O. Vysotsky, C. A. Hunter, K. Kato, K. Shinbo, F. Kaneko,
J. Mater. Chem. 2001, 11, 392.
286 4 8
H N O
H 11.36, N 2.21; found: C 81.2, H 11.4, N 2.2.
[
[
13] a) L. Wang, H. Liu, J. Hao, Chem. Commun. 2009, 1353; b) H. Li, J.
Hao, Z. Wu, J. Phys. Chem. B 2008, 112, 3705; c) G. Lu, X. Zhang,
X. Cai, J. Jiang, J. Mater. Chem. 2009, 19, 2417.
14] a) P. Sun, D. A. Jose, A. D. Shukla, J. J. Shukla, A. Das, J. F. Rath-
man, P. Ghosh, Langmuir 2005, 21, 3413; b) J. M. Kroon, E. J. R.
Sudholter, Langmuir 1995, 11, 214.
Acknowledgements
[
15] a) G. W. Gray, B. Jones, J. Chem. Soc. 1954, 1467; b) A. C. Bennis-
ton, P. Gunning, R. D. Peacock, J. Org. Chem. 2005, 70, 115.
16] a) H. Chou, C. T. Chen, K. F. Stork, P. W. Bohn, K. S. Suslick, J.
Phys. Chem. 1994, 98, 383; b) A. M. Goncalves da Silva, M. I. Viseu,
A. Malathi, P. Antunes, S. M. B. Costa, Langmuir 2000, 16, 1196.
17] P. Kubꢄt, K. Lang, K. Prochazkova, P. Anzenbacher Jr, Langmuir
This work was supported by the Department of Science and Technology,
Government of India. A.G. acknowledges CSIR for a Senior Research
Fellowship. A.D. thanks Dr. P. K. Ghosh for his keen interest in this
work.
[
[
[
2
003, 19, 422.
18] a) M. I. Viseu, A. M. Goncalves da Silva, P. Antunes, S. M. B. Costa,
Langmuir 2002, 18, 5772; b) V. Czikklely, H. D. Forsterling, H.
Kuhn, Chem. Phys. Lett. 1970, 6, 207; c) R. Azumi, M. Matsumoto,
Y. Kawabata, S. Kuroda, M. Sugi, L. G. King, M. J. Crossley, J. Phys.
Chem. 1993, 97, 12862; d) M. Kasha, H. R. Rawls, M. E. Ashraf,
Pure Appl. Chem. 1965, 11, 371.
[
1] a) Z. Wang, Z. Li, C. J. Medforth, J. A. Shelnutt, J. Am. Chem. Soc.
007, 129, 2440; b) M. L. Rodriguez-Mꢃndez, Y. Gorbunova, J. A.
de Saja, Langmuir 2002, 18, 9560; c) A. Ikeda, M. Nakasu, S. Ogasa-
wara, H. Nakanishi, M. Nakamura, J. I. Kikuchi, Org. Lett. 2009, 11,
2
1
163; d) G. Ramakrishna, D. A. Jose, D. K. Kumar, A. Das, D. K.
Palit, H. N. Ghosh, J. Phys. Chem. B 2006, 110, 9012; e) C. Perotti,
H. Fukuda, G. DiVenosa, A. J. MacRobert, A. Batlle, A. Casas, Br.
J. Cancer 2004, 90, 1660; f) A. D. F. Dunbar, T. H. Richardson, A. J.
McNaughton, J. Hutchinson, C. A. Hunter, J. Phys. Chem. B 2006,
[19] a) N. C. Maiti, S. Mazumder, N. Periasamy, J. Phys. Chem. B 1998,
102, 1528; b) T. Nagahara, K. Imura, H. Okamoto, A. Oguro, H. Im-
ahori, J. Phys. Chem. B 2005, 109, 19839.
1
10, 16646; g) A. J. McNaughton, A. Dunbar, W. Barford, T. H. Ri-
[20] a) H. T. Jung, B. Coldren, J. A. Zasadzinski, D. J. Iampietro, E. W.
Kaler, Proc. Natl. Acad. Sci. USA 2001, 98, 1353; b) X. Zhou, S. W.
chardson, Langmuir 2007, 23, 1759.
Chem. Asian J. 2010, 5, 352 – 358
ꢀ 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemasianj.org
357

A. Das et al.
FULL PAPERS
Kang, S. Kumar, R. R. Kulkarni, S. Z. D. Cheng, Q. Li, Chem.
Mater. 2008, 20, 3551.
[25] S. H. Seo, J. Y. Chang, G. N. Tew, Angew. Chem. 2006, 118, 7688;
Angew. Chem. Int. Ed. 2006, 45, 7526.
[
[
21] S. Lecuyer, T. Charitat, Europhys. Lett. 2006, 75, 652.
22] E. Tsuchida, T. Komatsu, K. Arai, K. Yamada, H. Nishide, J. H.
Fuhrhop, Langmuir 1995, 11, 1877.
23] A. Moscho, O. Orwar, D. T. Chiu, B. P. Modi, R. N. Zare, Proc. Natl.
Acad. Sci. USA 1996, 93, 11443.
[26] B. J. Battersby, G. A. Lawrie, G. T. Barnes, Colloids Surf. B 1999, 13,
179.
[27] P. Fromherz, D. Rueppel, FEBS Lett. 1985, 179, 155.
[28] D. D. Lasic, J. Colloid Interface Sci. 1990, 140, 302.
[
[
24] a) D. D. Lasic, J. Biochem. 1988, 256, 1; b) U. Lauf, A. Fahr, K.
Westesen, A. S. Ulrich, ChemPhysChem 2004, 5, 1246.
Received: July 31, 2009
Published online: December 22, 2009
358
www.chemasianj.org
ꢀ 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Asian J. 2010, 5, 352 – 358