Disclosing the distinct interfacial behaviors of structurally and configurationally diverse triazologlycolipids

Article abstract of DOI:10.1016/j.carres.2011.04.038

1- or 6-Triazologluco- and galactolipid derivatives bearing a lipid chain length of 16 carbons were efficiently constructed via click chemistry. The differentiation in their surface pressure-molecular area (π-A) isotherms first implies that these structur

Full text of DOI:10.1016/j.carres.2011.04.038

Carbohydrate Research 346 (2011) 1320–1326
Contents lists available at ScienceDirect
Carbohydrate Research
journal homepage: www.elsevier.com/locate/carres
Disclosing the distinct interfacial behaviors of structurally
and configurationally diverse triazologlycolipids
⇑
⇑
Xiao-Peng He, Xiaolian Xu, Hai-Lin Zhang, Guo-Rong Chen , Shouhong Xu , Honglai Liu
Key Laboratory for Advanced Materials and Institute of Fine Chemicals, East China University of Science and Technology, 130 Meilong Road, Shanghai 200237, PR China
a r t i c l e i n f o
a b s t r a c t
Article history:
1- or 6-Triazologluco- and galactolipid derivatives bearing a lipid chain length of 16 carbons were effi-
ciently constructed via click chemistry. The differentiation in their surface pressure-molecular area (p–
Received 10 February 2011
Received in revised form 8 April 2011
Accepted 26 April 2011
A) isotherms first implies that these structurally and configurationally diverse amphiphiles adopt differ-
ent distribution manner at air–water interfaces. The Langmuir–Blodgett (LB) films of the synthesized gly-
coconjugates on mica surface were subsequently prepared and visualized via atomic force microscopy
(AFM), which exhibited diverse topographies and possess different contact angles with water. These data
further suggest that the structural variation as well as epimeric identity of triazologlycolipids may result
in their distinct interfacial behaviors at the air–solid interface. Furthermore, the addition of increasing
Available online 3 May 2011
Keywords:
Glycolipid
Click chemistry
LB film
amounts of 1-triazologalactolipid 2 to poly-diacetylene (PDA) was determined to impact the
p–A iso-
therm of the latter, prompting us to further fabricate new colorimetrically detectable mixed-type vesicles
containing triazologlycolipids for biochemical studies.
Atomic force microscopy
p–A isotherm
Ó 2011 Elsevier Ltd. All rights reserved.
1. Introduction
surfactants.30 In addition, the surface characterizations of these
functional natural analogs were recently reported by Auzanneau
Glycolipids universally distribute in nature, constituting cell
membranes of almost all living organisms. They are widely applica-
ble in numerous biochemical and especially physicochemical
studies owning to their intrinsic amphiphilic feature as well as their
low toxicity and high biocompatiblity.1–11 However, the majority of
natural glycolipids encounter unsatisfactory limitations such as
their structural instability toward acidic and enzymatic cleavage
due to the presence of an O-glycosidic linkage between the lipid
aglycons and the glycons.
The regioselective and high-yielding Cu(I)-catalyzed alkyne–
azide 1,3-dipolar cycloaddition (a representative of click chemis-
try12), which was first defined by Sharpless and co-workers has
emerged as a versatile tool13 that enables the diversification of
various structurally-stable glycoconjugates with rigid triazole-
linkages for multiple practical uses.14–28 Nevertheless, the
preparation of triazole-linked glycolipids and the disclosure of their
potential functions have been relatively rarely reported.29–32
Loganathan and Paul first described the synthesis of series of
triazologlycolipid mimetics in which the triazole ring serves as a
solid connection between various carbohydrates and lipid chains.29
Krausz and co-workers subsequently showed the potential utility
of this unique non-ionic lipid class for the development of green
and co-workers,31 and us, independently.32
With a continued interest in the further exploration with regard
to the use of triazole-functionalized glycolipids, we describe here
their interesting interfacial behaviors. Structurally and configura-
tionally diversified triazologluco- and galactolipids bearing a 16
carbon lipid chain were efficiently prepared via click chemistry.
The apparent differentiations in their
p–A isotherms and LB film
characteristics on mica indicate that both the substitution position
of the lipid chain and the epimeric identity on carbohydrate moiety
significantly influences the interfacial properties of the produced
triazologlycolipids. Moreover, the
p–A isotherm of PDA was then
determined to be variable in the presence of the 1-triazologalactol-
ipid, prompting further fabrication of mixed-type vesicles colori-
metrically detectable for carbohydrate-related biochemical
investigations.
2. Results and discussion
2.1. Preparation of triazologlycolipids
1-Distributed natural glycolipid triazoloanalogs
1 and 2
(Scheme 1) were prepared previously, and were shown to have
promising adsorption ability on gold-surfaces.32 For the evaluation
of structure–interfacial activity relationship (SAR), 6-distributed
triazoles 8 and 9 were synthesized. The known methyl 6-azido-
⇑
Corresponding authors. Tel.: +86 21 64251942; fax: +86 21 64252921.
E-mail addresses: mrs_guorongchen@ecust.edu.cn (G.-R. Chen), xushouhong@e-
6-deoxy-a-D-glucopyranoside and galactopyranoside, 3 and 4,
cust.edu.cn (S. Xu).
0008-6215/$ - see front matter Ó 2011 Elsevier Ltd. All rights reserved.
doi:10.1016/j.carres.2011.04.038

X.-P. He et al. / Carbohydrate Research 346 (2011) 1320–1326
1321
OH
O
N
HO
OH
O
N
N
N
HO
HO
N
N
O
O
HO
O
O
OH
OH
1
2
N
N
N
N
R1
N3
O
(H2C)12
O
O
N
N
R1
a
b
R1
O
R2
+
O
O
O
R2
O
R2
HO
BnO
BnO
BnO
OMe
O
BnO
HO
OMe
OMe
3: R1 = H, R2 = OBn;
4: R1 = OBn, R2 = H
5
6: R1 = H, R2 = OBn (95%);
7: R1 = OBn, R2 = H (96%)
8: R1 = H, R2 = OH (78%);
9: R1 = OH , R2 = H (78%)
Scheme 1. Reagents and conditions: (a) Na ascorbate, CuSO4ꢀ5H2O, CH2Cl2/water, rt; (b) PdCl2/H2, MeOH, rt.
were previously prepared33,34 while the lipid alkyne 5 was readily
synthesized from commercially available palmitic acid in the pres-
ence of 1.5 equiv K2CO3 and propargyl bromide in anhydrous DMF.
The click reaction of azide 3 and 4 with the alkyne 5 proceeded
with the promotion of Na ascorbate and CuSO4ꢀ5H2O in CH2Cl2–
water (1:1, v/v) at rt, shown in Scheme 1. To our delight, the two
click adducts, 6 and 7, were afforded smoothly in excellent yields
of 95% and 96%, respectively. Subsequent hydrogenolysis catalyzed
by a reported PdCl2–H2 system (in MeOH)32 furnished the desired
triazologluco- (8) and galactolipid (9) in good yield of 78%. All new
compounds (6–9) were structurally confirmed by NMR and HRMS.
Table 1
The values of AL and pC of the glycolipids 1, 2, 8 and 9
Compound
AL (nm2)
pC (mN/m)
1
2
8
9
1.04
0.86
1.50
1.41
47.3
48.6
40.4
41.3
As shown in Table 1, the liftoff areas (AL, the molecular occupa-
tion area where the isotherm rises just from the baseline)35 of
1-substituted compounds (1.04 nm2 for 1 and 0.86 nm2 for 2) are
around 1.5-fold smaller than those of their 6-substituted counter-
parts (1.50 nm2 for 1 and 1.41 nm2 for 2), indicating that the
6-triazologlycolipids distribute less tightly on the air–water inter-
face than the 1-triazologlycolipids. The collapse pressures (
each triazologlycolipid monolayer were also obtained from Figure
1 and are summarized in Table 1. The C values of 6-triazologlycol-
2.2. Study of interfacial properties
2.2.1.
The
layers were first measured, which displayed similar shapes with-
out characteristic transitions (Fig. 1). The –r curves, obtained by
p–A isotherms of triazologlycolipids monolayers
pC) of
p
–A isotherms of various glycolipids (1, 2, 8 and 9) mono-
p
p
ipid monolayers (around 41 mN/m) are smaller than those of
1-triazologlycolipid ones (around 48 mN/m), demonstrating that
the latter is more stable than the former at gas–liquid interface.
plotting various surface pressures as a function of their calculated
r (compressibility) values (equation indicated in the Supplemen-
tary data) were then prepared (Fig. S-1, Supplementary data).
All r values of these monolayers are in the range of 0.018–
0.060 m/mN, revealing that they would be most likely in the liquid
expanded phase.35–42
In addition, the AL value of 1-distributed galactolipid
2
(0.86 nm2) is smaller than that of the glucolipid 1 (1.04 nm2),
which means that the former bearing a C4 axial hydroxyl bond
may occupy lesser space on the air–water interface compared to
that of the latter, which has an equatorial hydroxyl bond at C4.
However, we observed that the difference in AL value between 6-
distributed galactolipid 9 (1.41 nm2) and glucolipid 8 (1.50 nm2)
is much smaller than that between the 6-distributed derivatives
(8 and 9). This could be most likely ascribed to the existence of
C6-triazololipid on glycoside 8 and 9, which is spatially much
closer to the C4-OH of the monosaccharide moiety compared to
the C1-triazololipid on compound 1 and 2, furnishing excess steric
hindrance that reduces the C4-epimeric effect of carbohydrates
toward the interfacial property of the corresponding amphiphiles.
2.2.2. LB films of triazologlycolipids
To investigate their interfacial properties in a more detailed
way, the LB films of the four synthesized compounds (1, 2, 8 and
9) under various surface pressures (5, 15, 25 and 35 mN/m) were
prepared on mica surface and their AFM images were obtained
and shown in Figure 2 (only the results of
p equals to the lowest
5 mN/m and the highest 35 mN/m were displayed for a clearer
comparison). Cross sections of the AFM images obtained by off-line
analysis software were also shown while the hydrophobicity of
these films was studied via the water contact angles h, summarized
in Table 2.
Figure 1. The
represent those of compounds
respectively, from left to right.
p–A isotherms of various triazologlycolipid monolayers. The curves
2 (gal-1), 1 (glc-1), 9 (gal-6) and 8 (glc-6),

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X.-P. He et al. / Carbohydrate Research 346 (2011) 1320–1326
Figure 2. AFM images (4 ꢁ 4
l
m) of (a) compound 1,
= 35 mN/m; (g) compound 9,
m; ordinate: ꢂ0.1 to 0.1 nm).
p
= 5 mN/m; (b) compound 1,
p
= 35 mN/m; (c) compound 2,
p = 5 mN/m; (d) compound 2, p = 35 mN/m; (e) compound
8,
p
= 5 mN/m; (f) compound 8,
p
p
= 5 mN/m; (h) compound 9, p
= 35 mN/m. Cross sections obtained along the black lines in AFM topographic
images a–h are also shown underneath (abscissa: 0–4.0
l
Clearly, the AFM topographies between the 1-susbtituted
(Fig. 2a–d) and 6-substituted (Fig. 2e–g) triazologlycolipids
appeared to be distinct under both low and high surface pressures.
As shown in Figure 2a, a low and gapped platform of 1-triazologlu-
colipid 1 having a terrace of 0.5 nm in height was formed at
increased surface pressure (p = 35 mN/m). Instead, some small
terraces with less than 1 nm in height were observed (Fig. 2f) right
on the originally formed molecular film. Likewise, the LB film of 6-
triazologalactolipid 9 with wildly distributed pits of about 2 nm
was previously formed on mica under the pressure of 5 mN/m
(Fig. 2g), whereas increased pressure (35 mN/m) led to the similar
formation of even more densely functionalized terraces with
height of less than 1 nm, displayed in Figure 2h.
Interestingly, the 6-triazologlycolipids may constitute thicker
LB films compared to their 1-triazologlycolipids counterparts
under low surface pressure. When the pressure increased, the LB
films of the latter tended to become more compact and thicker
whereas additional terraces appeared on that of the former. In an
attempt to propose an explanation toward such phenomenon,
the plausible morphological changes of LB films containing the 6-
or 1-triazologlycolipids from air–water interface to mica surface
were illustrated in Figure 3.
p
= 5 mN/m whereas such a platform tended to become an inte-
grated and thicker molecular layer when the surface pressure in-
creased to 35 mN/m (Fig. 2b). In contrast, the LB film of
1-triazologalactolipid 2 (Fig. 2c) was initially more compactly
formed on mica at
p = 5 mN/m compared to that of its epimer 1
(Fig. 2a). With successively increased pressure (35 mN/m), this film
was structurally tightened and thickened as shown in Figure 2d
similar to the topographical change of the LB film containing
compound 1 from Figure 2a and b.
Nevertheless, the topographies of the LB films formed by the 6-
triazologlycolipids are dissimilar under different pressures. Pits of
about 2 nm in depth were observed in the LB film of 6-triazologlu-
colipid 8 (Fig. 2e,
p
= 5 mN/m), which then disappeared with
We postulate that by pulling up the mica slice from water, the
6-triazologlycolipids attached on mica surface would adopt a
standing posture with the lipid end being vertical-like to the sur-
face (Fig. 3b). However, considering the comparatively thinner LB
films formed by the 1-triazologlyclipids (around 0.5 nm vs
2.0 nm in thickness of 6-triazologlycolipid films), these molecules
would possibly choose to sprawl on the surface as shown in Figure
3a.43 Upon the increase in pressure, the 1-distributed amphiphiles
would probably ‘stand up’ with erected lipid chains toward air
(Fig. 3c) and distribute more tightly on the mica surface deduced
by their observed AFM topographies (Fig. 2b and d). In contrast,
with increased pressure, the LB film formed by the initially
Table 2
The h (water contact angle) values of LB films formed by glycolipids 1, 2, 8 and 9
Compound
ha (°)
p
= 5 mN/m
p
= 15 mN/m
p
= 25 mN/m
p = 35 mN/m
1
2
8
9
15.05
25.59
22.01
19.73
22.13
33.93
22.62
20.11
25.22
31.62
55.49
22.47
22.71
43.20
22.58
21.74
a
Values are means of six experiments.

X.-P. He et al. / Carbohydrate Research 346 (2011) 1320–1326
1323
Figure 3. Schematic representation of (a) 1-triazologlycolipid assembly on mica surface under low pressure; (b) 1-triazologlycolipid assembly on mica surface under high
pressure, and (c) 6-triazologlycolipid assembly on mica surface under low pressure; (b) 6-triazologlycolipid assembly on mica surface under high pressure.
‘stand-up’ 6-distributed amphiphiles would be prone to become
saturated and the surplus molecules might have been partially
extruded from the first layer, illustrated in Figure 3b. We speculate
that an overlapped molecular loop instead of a double layer was
generated since the height of the additionally emerged terraces
observed from Figure 2f and h is less than 1 nm, being onefold
smaller in value than that of the bottom film under low pressure
(around 2 nm) shown in Figure 2e and g.
As shown in Table 2, at lowest pressure (5 mN/m), the water
contact angle (h) of LB film of 1-triazologlucolipid 1 (15°) is smaller
than that of galactolipid 2 (26°), indicating that the LB film formed
by the former is less hydrophobic than that formed by the latter.
Under gradually increased pressure, the hydrophobicity of both
films simultaneously increased with the galactosyl film 2 being
always more hydrophilic. However, the water contact angles of
6-triazologlycolipids were determined not to be significantly
impacted by both the epimeric effect of monosaccharide moiety
and the increasing pressure.
molecule of 1-modified galactoside 2 are always apparently smal-
ler than those of its epimer 1 under various surface pressures,
which implies that the former could generate tighter molecular
films than the latter. Consequently, the more compact monolayer
containing compound 2 would be more hydrophobic with larger
values in contact angle degree with water. In sharp contrast, the
inconspicuous diversity in p–A isotherms between the 6-modified
glycosyl epimers (7 and 8) suggests their similar molecular film
formation, which might successively render their similar h values.
Such similarity between these two molecules could be ascribed to,
as described above, the existence of bulky C6-triazololipid moiety
spatially contiguous to the glycosyl C4-position, diminishing their
epimeric effect on the corresponding interfacial properties.
2.2.3. PDA-triazologlycolipid mixture
Previous reports have supported that the mixture of PDA with
natural glycolipids possessing colorimetrically detectable proper-
ties may represent a promising strategy for producing vesicles
applicable in numerous biochemical studies including sugar-med-
iated cell–cell recognition, drug release and gene transfection.44,45
We have previously observed from the
p–A isotherms (Fig. 1) of
the triazologlycolipid films that the areas occupied by each

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X.-P. He et al. / Carbohydrate Research 346 (2011) 1320–1326
solutions using tetramethylsilane as the internal standard (chemi-
cal shifts in departs per million). Optical rotations were measured
using a Perkin-Elmer 241 polarimeter at room temperature and a
10 cm length cell of a 1 mL volume. Concentrations are given in
g/100 mL. Low and high resolution mass spectra were recorded
on a Waters LCT Premier XE spectrometer using standard condi-
tions (ESI, 70 eV).
4.2. General procedure for click reaction
To a well-stirred biphasic solution of the sugar azide (1 equiv)
and the lipid alkyne (2 equiv) in CH2Cl2 (8–10 mL) and H2O
(8 mL), were added CuSO4ꢀ5H2O (3 equiv) and sodium ascorbate
(6 equiv) successively. After stirring for 6 h, the resulting mixture
was diluted with CH2Cl2 (10 mL) and washed with brine
(2 ꢁ 5 mL). The combined organic layers were dried over MgSO4
and then concentrated under reduced pressure to give a crude
residue, which was purified by column chromatography.
Figure 4. The
p–A isotherms of PDA alone, PDA/compound 2 (molar fraction of
compd 2) = 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9 and compound
respectively, from left to right.
2 alone,
4.2.1. Methyl 2,3,4-Tri-O-benzyl-6-deoxy-6-(10H-10,20,30-
triazolyl-4-yl-hexadecanoate)-a-D-glucopyranoside (6)
From compound 3 (200 mg, 0.408 mmol) and 5 (240.4 mg,
0.817 mmol), column chromatography (petroleum ether–EtOAc
Consequently, the
p–A isotherms of PDA–triazologlycolipid
8:1?3:1) afforded
94.9%). TLC: Rf = 0.29 (petroleum ether–EtOAc, 3:1); [
6
as
a
white ceraceous solid (303.9 mg,
+54.9 (c
mixtures including various molar fractions of the selected 1-
triazologalactolipid 2 were preliminarily investigated as shown in
Figure 4. The isotherm of the pure PDA is almost linear, which indi-
cates its solid membrane state, whereas the presence of increasing
amounts of 2 may gradually lead the corresponding isotherm to
liquid state. Moreover, the stability of the membrane formed by
the PDA–triazologalacolipid mixture could also be enhanced with
the increase of the latter considering their increasing pC values.
These data suggest that the blending of triazologlycolipid with
PDA may alter considerably the physicochemical property of the
latter, which further prompted us to fabricate a mixed-type vesicle
containing these two components for the above-mentioned
biochemical studies.
a
]
D
0.3, CH2Cl2); 1H NMR (400 MHz, CDCl3): d 7.64 (s, 1H), 7.36–7.28
(br m, 15H), 5.19 (dd, J = 12.8, 20.4 Hz, 2H), 4.98 (d, J = 10.7 Hz,
1H), 4.90 (d, J = 10.9 Hz, 1H), 4.81 (d, J = 10.8 Hz, 1H), 4.77 (d,
J = 12.0 Hz, 1H), 4.72 (d, J = 10.9 Hz, 1H), 4.62 (d, J = 12.0 Hz, 1H),
4.55 (d, J = 3.4 Hz, 1H), 4.52 (d, J = 2.4 Hz, 1H), 4.47 (dd, J = 6.1,
14.2 Hz, 1H), 4.00 (t, J = 9.2 Hz, 1H), 3.93 (br m, 1H), 3.42 (dd,
J = 3.4, 9.6 Hz, 1H), 3.18 (s, 3H), 3.14 (t, J = 9.4 Hz, 1H), 2.29 (t,
J = 7.6 Hz, 2H), 1.59 (br m, 2H), 1.25 (br s, 24H), 0.88 (t, J = 6.7 Hz,
3H); 13C NMR (100 MHz, CDCl3): d 173.4, 142.7, 138.2, 137.8,
128.3, 128.3, 128.3, 128.0, 127.8, 127.8, 127.6, 125.0, 97.9, 81.7,
79.8, 77.8, 75.6, 74.8, 73.3, 68.9, 57.3, 55.1, 50.5, 34.0, 31.8, 29.5,
29.5, 29.4, 29.3, 29.2, 29.1, 29.0, 24.7, 22.5, 14.0; LRESIMS: m/z
calcd for [C47H65N3O7+H]+: 784.5, found: 784.4.
3. Conclusion
4.2.2. Methyl 2,3,4-tri-O-benzyl-6-deoxy-6-(10H-10,20,30-triazolyl-
4-yl-hexadecanoate)-a-D-galactopyranoside (7)
From compound 4 (226 mg, 0.462 mmol) and 5 (271.6 mg,
0.923 mmol), column chromatography (petroleum ether–EtOAc,
In summary, the interfacial behaviors of four 1- and 6-triazolo-
glycolipids synthesized via click chemistry were comparatively
studied by evaluating their
p–A isotherms at the air–water inter-
face and LB film characteristics on mica surface via AFM technique,
and water contact angle measurement. We estimate that such
behaviors are largely dependent on both the structural and config-
urational diversity of these glycoconjugates. Furthermore, the se-
lected 1-triazologalactolipid was found to enhance the stability
of pure PDA membrane at water–air interface. This further
prompts us to fabricate novel structurally stable triazologlycoli-
pid-containing mixed-type vesicles colorimetrically detectable for
biochemical purposes such as the probing of carbohydrate-medi-
ated cell–cell recognition and drug release using carbohydrate as
the carrier.
8:1?3:1) afforded
96.0%). TLC: Rf = 0.24 (petroleum ether–EtOAc, 3:1); [
7
as
a
white ceraceous solid (347.5 mg,
+37.1 (c
a]
D
0.2, CH2Cl2); 1H NMR (400 MHz, CDCl3): d 7.52 (s, 1H), 7.42–7.29
(br m, 15H), 5.15 (s, 2H), 5.04 (d, J = 11.5 Hz, 1H), 4.91 (d,
J = 11.7 Hz, 1H), 4.84 (d, J = 12.0 Hz, 1H), 4.76 (d, J = 11.9 Hz, 1H),
4.68 (d, J = 12.0 Hz, 1H), 4.63 (d, J = 11.5 Hz, 1H), 4.60 (d,
J = 3.4 Hz, 1H), 4.32 (dd, J = 9.3, 14.0 Hz, 1H), 4.19 (dd, J = 3.0,
14.0 Hz, 1H), 4.03 (dd, J = 3.6, 10.0 Hz, 1H), 3.99 (br dd, J = 2.3,
9.4 Hz, 1H), 3.93 (dd, J = 2.5, 10.2 Hz, 1H), 3.84 (br s, 1H), 2.98 (s,
3H), 2.27 (t, J = 7.7 Hz, 2H), 1.57 (m, 2H), 1.25 (br s, 24H), 0.88 (t,
J = 6.7 Hz, 3H); 13C NMR (100 MHz, CDCl3): d 173.2, 142.5, 138.2,
138.0, 137.7, 128.4, 128.3, 128.2, 128.1, 127.9, 127.8, 127.6,
127.5, 127.4, 124.8, 98.5, 78.5, 75.9, 74.8, 74.4, 73.6, 73.4, 69.2,
57.1, 54.9, 51.0, 33.8, 31.7, 29.4, 29.4, 29.3, 29.2, 29.1, 29.0, 28.8,
24.6, 22.4, 13.9.
4. Experimental section
4.1. General
All purchased chemicals and reagents are of high commercially
available grade. Solvents were purified by standard procedures. All
reactions were monitored by TLC (thin-layer chromatography)
performed on E-Merck aluminum percolated plates of Silica Gel
60F-254 with detection by UV (kmax = 254) or by spraying with
6 N H2SO4 and charring at 300 °C. 1H and 13C NMR spectra were
recorded on a Bruker AM-400 spectrometer in CDCl3 or CD3OD
4.3. General procedure for debenzylation
To a solution of benzylated glycolipids in MeOH (8–16 mL) was
added PdCl2 (0.5 equiv) and such mixture was stirred vigorously
under hydrogen atmosphere for 20 min. The hydrogen gas was
released rapidly and the mixture system was refilled with H2 and
stirred for another 20 min. The resulting mixture was then filtered

X.-P. He et al. / Carbohydrate Research 346 (2011) 1320–1326
1325
and concentrated under reduced pressure to give the crude residue
Co., China). The volume of MiliQ water droplet was 0.5
l
L. The h
which was purified by column chromatography.
value of mica is nearly zero.
4.3.1. Methyl 6-deoxy-6-(10H-10,20,30-triazolyl-4-yl-
4.7. Observation of surface morphology
hexadecanoate)-
From compound 6 (265 mg, 0.338 mmol), column chromatogra-
phy (EtOAc–EtOH, 12:1?8:1) afforded as white solid
(135.1 mg, 77.8%). TLC: Rf = 0.66 (EtOAc–MeOH, 6:1); [ +49.2
a-D-glucopyranoside (8)
The morphology of glycolipid LB films on mica was obtained by
using AFM (AJ-III, Aijian nanotechnology Inc., China) in air with a
tapping mode at room temperature. The cantilever of AFM tip
was (Mikro Masch Co., Russia) a Si pyramidal tip with a spring con-
stant of 3.0 N/m. All images were obtained at least five macroscop-
ically separated areas and were analyzed off-line by using the
software provided with the AFM instruments.
8
a
a
]
D
(c 0.2, CH3OH); 1H NMR (400 MHz, CDCl3): d 7.76 (s, 1H), 5.20 (s,
2H), 4.71 (br s, 2H), 4.63 (br d, J = 13.8 Hz, 1H), 3.89 (br s, 1H),
3.74 (t, J = 8.7 Hz, 1H), 3.42 (br d, J = 7.8 Hz, 1H), 3.24 (s, 3H),
3.12 (t, J = 8.7 Hz, 1H), 2.30 (t, J = 7.5 Hz, 2H), 1.59 (m, 2H), 1.25
(br s, 24H), 0.88 (t, J = 6.6 Hz, 3H); 13C NMR (100 MHz, CDCl3): d
173.5, 142.7, 125.7, 99.5, 73.6, 71.6, 70.7, 69.9, 57.2, 55.2, 50.8,
34.0, 31.8, 29.6, 29.6, 29.5, 29.4, 29.2, 29.2, 29.0, 24.7, 22.6, 14.0;
HRESIMS: m/z calcd for [C26H47N3O7+H]+: 514.3492, found:
514.3489.
Acknowledgments
This work was financial supported by National Natural Science
Foundation of China (Grant Nos. 20876045 and 21076071), Shang-
hai Science and Technology Community (No. 10410702700) and
the Fundamental Research Funds for the Central Universities (No.
WK1013002). X.-P. He also gratefully acknowledges the French
Embassy for the financial support of a co-tutored doctoral program.
4.3.2. Methyl 6-deoxy-6-(10H-10,20,30-triazolyl-4-yl-
hexadecanoate)-
From compound 7 (280 mg, 0.357 mmol), column chromatogra-
phy (EtOAc–EtOH, 12:1?8:1) afforded as white solid
(143.7 mg, 78.4%). TLC: Rf = 0.46 (EtOAc–MeOH, 6:1); [ +50.1
a-D-galactopyranoside (9)
9
a
a]
D
Supplementary data
(c 0.1, CH3OH); 1H NMR (400 MHz, CDCl3): d 7.72 (s, 1H), 5.21 (s,
2H), 4.78 (d, J = 3.3 Hz, 1H), 4.68 (dd, J = 4.5, 14.4 Hz, 1H), 4.59
(dd, J = 8.8, 14.4 Hz, 1H), 4.16 (br dd, J = 5.5, 8.2 Hz, 1H), 3.93 (br
s, 1H), 3.82 (br dd, J = 3.8, 10.4 Hz, 1H), 3.78 (br dd, J = 2.9,
9.2 Hz, 1H), 3.17 (s, 3H), 2.30 (t, J = 7.5 Hz, 2H), 1.59 (m, 2H), 1.25
(br s, 24H), 0.88 (t, J = 6.7 Hz, 3H); 13C NMR (100 MHz,
CDCl3+CD3OD): d 173.4, 142.0, 125.0, 99.5, 69.4, 69.2, 68.8, 68.1,
56.4, 54.1, 50.7, 33.3, 31.2, 28.9, 28.9, 28.8, 28.7, 28.6, 28.5, 28.3,
24.1, 21.9, 13.0; HRESIMS: m/z calcd for [C26H47N3O7+H]+:
514.3492, found: 514.3482.
Supplementary data associated with this article can be found, in
the online version, at doi:10.1016/j.carres.2011.04.038.
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