Synthesis and self-assembly of novel hydrazide derivatives containing multi-alkoxy chains with different lengths

Article abstract of DOI:10.1016/j.molstruc.2008.06.018

We report on the synthesis and self-assembly of two novel types of hydrazide derivatives, e.g. 1,4-bis[(3,4,5-trialkoxyphenyl)-dihydrazide]-2,5-diethylphthalate (C-Tn, n = 7, 10, 12 and 16) and N',N'-bis[3,4,5-tris(dodecyloxy)benzamido]-pyromellitic diimi

Full text of DOI:10.1016/j.molstruc.2008.06.018

Journal of Molecular Structure 892 (2008) 490–494
Contents lists available at ScienceDirect
Journal of Molecular Structure
journal homepage: www.elsevier.com/locate/molstruc
Synthesis and self-assembly of novel hydrazide derivatives containing
multi-alkoxy chains with different lengths
Xiao-bing Zhang a,b, Min Li a,
*
a Key Laboratory for Automobile Materials, Ministry of Education, PRC and Department of Material Science and Engineering, Jilin University, 10 Qianwei Road,
Changchun, Jilin Province 130012, China
b School of Safety Science and Engineering, Henan Polytechnic University, Jiaozuo 454000, China
a r t i c l e i n f o
a b s t r a c t
Article history:
We report on the synthesis and self-assembly of two novel types of hydrazide derivatives, e.g. 1,
4-bis[(3,4,5-trialkoxyphenyl)-dihydrazide]-2,5-diethylphthalate (C-Tn, n = 7, 10, 12 and 16) and N’,
N’-bis[3,4,5-tris(dodecyloxy)benzamido]-pyromellitic diimide (BI-C-T12). They were confirmed to exhi-
bit strong gelation ability in several apolar organic solvents, such as benzene, 1,2-dichloroethane and
chloroform. SEM images of the xerogels revealed that the gels consist of twist fibrous aggregates. Both
FT-IR and 1H NMR studies confirmed that the intermolecular hydrogen bonding and van der Waals inter-
actions were the major driving forces for the self-assembly of the molecules during gelling.
Ó 2008 Elsevier B.V. All rights reserved.
Received 30 March 2008
Received in revised form 19 June 2008
Accepted 19 June 2008
Available online 26 June 2008
Keywords:
Self-assembly
Hydrazide derivatives
Organogel
Hydrogen bonding
1. Introduction
molecular hydrogen bonding between –C@O group and –N-H
group and van der Waals interactions are the main driving forces
Self-assembling processes are common throughout nature
and technology [1]. Self-assembled materials, such as liquid
crystals and organogels, formed by non-covalent bonding have
attracted much attention because they are good candidates for
the next generation of materials, for which dynamic function,
environmental benignity, and low energy processing are re-
quired [2,3].
Organogels, in which organic solvents are gelled by low molec-
ular-weight compounds (organogelators), have attracted much
interest as a result of their unique features and potential applica-
tions for new organic soft materials [4]. Most of the organogelators
reported in the literatures [5–10], can form a three-dimensional
network by self-organization through non-covalent interactions
for the self-assembly of the molecules.
2. Experimental
2.1. Characterization
Melting point (mp) was measured on a WRX-1S instrument.
Infrared (IR) spectra were recorded with a Perkin-Elmer spectrum
one B spectrometer. 1H NMR spectra were recorded on a Varian-
Unity spectrometer at 300 MHz using tetramethylsilane (TMS) as
an internal standard. The FE-SEM observation was carried out
using a JSM-6700F field emission scanning electron microscope.
The samples were dried overnight in a vacuum before the observa-
tion. The dried gels were sputtered using a gold target.
Gelation test: A mixture of a weighed gelator in organic solvents
(1 mL) in a sealed test tube was heated around the boiling point
until a clear solution appeared. The test tube was allowed to stand
for 4 h in refrigeratory thermostated 5 °C. The gel formation was
evaluated by the ‘‘stable to inversion of a test tube” method [14].
such as hydrogen bonding, van der Waals interactions, p-stacking,
and coordination. In our previous papers, we reported the gelatini-
zation behavior of a series of wedge-shaped [11], twin-tapered [12]
and side-on [13] hydrazide derivatives with different alkoxy
chains.
Here, we report the synthesis of the newly designed hydrazide
derivatives, e.g., 1,4-bis[(3,4,5-trialkoxyphenyl)-dihydrazide]-2,5-
diethylphthalate (C-Tn, n = 7, 10, 12 and 16) and N0,N0-bis[3,4,5-
tris(dodecyloxy)benzamido]-pyromellitic diimide (BI-C-T12) and
their gelatinization behaviors. Our results showed that the inter-
2.2. Synthesis
For all the reactions, magnetic stirrers were used. Commercially
available reagents were used without further purification. All reac-
tions were monitored by thin layer chromatography (TLC). Com-
pounds were visualized with UV light at 254 nm and 365 nm.
* Corresponding author. Tel.: +86 431 85168254; fax: +86 431 85168444.
E-mail address: minli@mail.jlu.edu.cn (M. Li).
0022-2860/$ - see front matter Ó 2008 Elsevier B.V. All rights reserved.
doi:10.1016/j.molstruc.2008.06.018

X.-b. Zhang, M. Li / Journal of Molecular Structure 892 (2008) 490–494
491
Two types of hydrazide derivatives named as C-Tn (n = 7, 10, 12
and 16) and BI-C-T12 were synthesized according to the synthetic
route in Scheme 1. The chemical structures of the hydrazide com-
pounds were confirmed by FT-IR, 1H NMR spectroscopy and ele-
mental analysis.
FT-IR (KBr disc cmꢀ1) 3265, 2954, 2920, 2850, 1627, 1581, 1526,
1498, 1468, 1425, 1389, 1347, 1242, 1120, 991, 859, 786, 757, 720,
664.
2.2.1.3. 3,4,5-Tridodecyloxybenzoic hydrazide (T12). White powder
(yield 60%, mp 114–115 °C). 1H NMR (CDCl3 ppm from TMS,
300 MHz) 10.71 (s, 1H), 7.16 (s, 4H), 4.39-4.40 (s, 2H), 3.80 (t,
2H, J = 4.5 Hz), 3.78 (t, 1H), 1.65-1.88 (m, 54H), 1.00 (t, 9H,
J = 9.0 Hz).
2.2.1. Synthesis of 1,4-bis[(3,4,5-trialkoxyphenyl)-dihydrazide]-2,5-
diethylphthalate (C-Tn, n = 7, 10, 12 and 16)
2.2.1.1. 3,4,5-Triheptyloxybenzoic hydrazide (T7). Methyl gallate
(MG) (3.68 g, 0.02 mol) was dissolved in 80 mL dry acetone, 1-bro-
moheptane (10.8 g, 0.06 mol), anhydrous potassium carbonate
(K2CO3) (15 g), KI (1.0 g), were added. The reaction mixture was re-
fluxed for about 50 h. The hot reaction mixture was filtered and the
residue was thoroughly washed twice with acetone. The solvent
was removed from the combined filtrates in a rotary evaporator,
and the residual product (3,4,5-triheptyloxybenzoic acid methyl
ester) was collected. The ester and hydrazine monohydrate
(20 mL) were added into 40 mL ethanol, and the mixture was re-
fluxed for about 50 h. The reaction mixture was then frozen and
the product precipitated. The product was filtered and recrystal-
lized from methanol to give 4.9 g white solid (yield 63%, mp
107–108 °C).
FT-IR (KBr disc cmꢀ1) 3265, 2954, 2920, 2850, 1627, 1581, 1526,
1498, 1468, 1425, 1389, 1347, 1242, 1120, 991, 859, 786, 720, 664.
2.2.1.4. 3,4,5-Tricetyloxybenzoic hydrazide (T16). White powder
(yield 63%, mp 117–118 °C). 1H NMR (CDCl3 ppm from TMS,
300 MHz) 10.71 (s, 1 H), 7.16 (s, 4H), 4.39–4.40 (s, 2H), 3.80 (t,
4H, J = 4.5 Hz), 3.78 (t, 2H), 1.65–1.88 (m, 78H), 1.00 (t, 9H,
J = 9.0 Hz).
FT-IR (KBr disc cmꢀ1) 3265, 2954, 2920, 2850, 1627, 1581, 1498,
1468, 1425, 1389, 1347, 1242, 1120, 991, 859, 786, 720, 665.
2.2.1.5. Diethyl 2,5-dicarboxylterephthalate (B). Phthalic anhydride
(A) (4.36 g, 20 mmol) was dissolved in 120 mL ethanol, and the
mixture was refluxed for about 8 h [15]. After ethanol being
vaporized, the reaction mixture was frozen for about 24 h and
the crude product precipitated. The precipitate was filtered,
washed thoroughly with water, dried completely, and recrystal-
lized from ether to give 2.75 g white crystal (yield 44%, mp
280–281 °C).
1H NMR (d-DMSO ppm from TMS, 300 MHz) 10.71 (s, 1H), 7.16
(s, 4H), 4.40 (s, 2H), 3.80 (t, 2H, J = 4.5 Hz), 3.78 (t, 1H), 1.65-1.88
(m, 24H), 1.00 (t, 9H, J = 9.0 Hz).
FT-IR (KBr disc cmꢀ1) 3317, 3258, 2954, 2928, 1625, 1580, 1519,
1498, 1466, 1425, 1390, 1348, 1303, 1242, 1116, 1069, 1041, 1011,
949, 921, 861, 842, 810, 788, 767, 752, 724, 663, 590.
1H NMR (d-DMSO ppm from TMS, 300 MHz) 13.82 (s, 2H), 7.98
(s, 2H), 4.29-4.31 (q, 4H), 1.29 (t, 6H, J = 6.0 Hz).
2.2.1.2. 3,4,5-Tridecyloxybenzoic hydrazide (T10). White powder
(yield 62%, mp 112–113 °C). 1H NMR (CDCl3 ppm from TMS,
300 MHz) 10.71 (s, 1 H), 7.16 (s, 4H), 4.39-4.40 (s, 2H), 3.80 (t, 2H,
J = 4.5 Hz), 3.78 (t, 1H), 1.65–1.88 (m, 42H), 1.00 (t, 9H, J = 9.0 Hz).
FT-IR (KBr disc cmꢀ1) 2985, 2960, 2941, 2666, 2581, 1731, 1702,
1505, 1496, 1432, 1391, 1369, 1304, 1258, 1163, 1142, 1105, 1018,
918, 860, 794, 736, 654, 574.
HO
CH3 ( CH2
)
O
O
n-1
O
O
C
i
ii
HO
C
OCH3
CH3
CH3
CH
(
(
)
O
NHNH2
2
n-1
HO
CH
)
MG
2
Tn
n-1
O
O
COOC2H5
COOH
COOC2H5
COCl
iii
iv
HOOC
H5C2OOC
ClOC
O
O
H5C2OOC
O
O
A
B
C
CH3
( CH2
)
O
COOC2H5
CONHNHOC
O
(
)
CH2
(
CH3
n-1
n-1
v
CH3
CH
(
(
)
O
)
2 n-1
CONHNHOC
H5C2OOC
O
CH2
CH3
n-1
O
(
)
CH2
CH3
CH3
CH
)
O
2
n-1
n-1
C-Tn (n= 7, 10, 12, 16)
CH3 (CH2
)
11
O
O
O
O
( )
CH2
11
CH3
vi
CH3
CH3
CH
2
(
)
11
O
COHN
N
N
NH OC
(
)
11
O
CH2
CH3
O
(
)
CH
(
)
CH2
CH3
O
2
O
O
11
11
BI-C-T12
Scheme 1. Synthetic route for novel hydrazide derivatives. Reagents and conditions: (i) CnH2n+1Br, acetone, K2CO3, reflux 50 h; (ii) hydrazine monohydrate, ethanol, reflux,
50 h; (iii) ethanol, reflux 8 h; (iv) SOCl2, reflux 15 h; (v) Tn, THF, pyridine, rt 10 h; (vi) pyridine/toluene (1/5, V/V), reflux 96 h.

492
X.-b. Zhang, M. Li / Journal of Molecular Structure 892 (2008) 490–494
2.2.1.6. 1,4-Bis[(3,4,5-triheptyloxyphenyl)-dihydrazide]-2,5-diet-
hylphthalate (C-T7). Compound B (1.55 g, 5 mmol) was dissolved
in thionyl chloride (SOCl2) and refluxed for 15 h. The superfluous
SOCl2 was vaporized from the reaction mixture to get terephtha-
loyl chloride (C). Compound C was dissolved in 70 mL tetrahydro-
furan (THF), then 3,4,5-triheptyloxybenzoic hydrazide (4.78 g,
0.01 mol) and 3 mL pyridine was added, the reaction mixture
was cooled to 0–4 °C by using an ice-bath and stirred for about
8 h. The mixture was poured into 500 mL water and product was
collected through filtration and dried completely. The product
was recrystallized from chloroform to give 4.15 g white powder
(yield 68%, mp 225–226 °C).
was recrystallized from dichloromethane to give 0.97 g pale yellow
solid (yield 62%, mp 173–174 °C).
1H NMR (CDCl3 ppm from TMS, 300 MHz) 8.45 (s, 2H), 8.06 (s,
2H), 7.10 (s, 4H), 4.03 (t, 12H, J = 6.0 Hz), 1.62-1.84 (m, 12H),
1.27-1.47 (m, 114H), 0.88 (t, 18H, J = 4.5 Hz).
FT-IR (KBr disc cmꢀ1) 3255, 2923, 2852, 1793, 1750, 1663, 1585,
1492, 1468, 1429, 1390, 1338, 1221, 1119, 1021, 914, 840, 760,
721, 709, 605, 559.
Anal. Calcd for C96H158N4O12: C, 73.94%; H, 10.14%; N, 3.59%.
Found: C, 73.96%; H, 10.16%; N, 3.39%.
3. Results and discussion
1H NMR (d-DMSO ppm from TMS, 300 MHz) 10.34 (s, 2H), 10.01
(s, 2H), 7.96 (s, 2H), 7.02 (s, 4H), 4.30 (q, 4H), 3.96 (t, 2H, J = 6.0 Hz),
3.80 (t, 4H), 1.60–1.76 (m, 12H), 1.27–1.47 (m, 66H), 0.88 (t, 18H,
J = 3.0 Hz).
3.1. Synthesis
The synthetic route for the novel hydrazide derivatives is shown
in Scheme 1. Compound C-Tn’s were prepared through the con-
densation of terephthaloyl chloride (C) with 3,4,5-trialkoxybenzoic
hydrazide (Tn), while BI-C-T12 was obtained based on intramolec-
ular dealcoholizing of C-T12.
FT-IR (KBr disc cmꢀ1) 3183, 2955, 2926, 2856, 1728, 1666, 1600,
1578, 1498, 1455, 1383, 1337, 1299, 1236, 1131, 1117, 1021, 914,
851, 826, 772, 733, 665, 538.
Anal. Calcd for C70H110N4O14: C, 68.29%; H, 8.94%; N, 4.55%.
Found: C, 68.33%; H, 9.14%; N, 4.45%.
As can be seen from the synthetic scheme, partially esterifica-
tion of the phthalic anhydride (A) results in a mixture of diethyl
2,5-dicarboxylterephthalate (B), diethyl 2,4-dicarboxylterephtha-
late (B’) containing two carboxyls and other by-products. Most B’
and other esterifiable products can be easily removed from the
mixture through recrystallization from ethanol [15]. Because of
good solublility in ether than that of compound B, compound B’
can be completely eliminated from the mixture of B and B’, then
the pure compound B being obtained. The diimide compound BI-
C-T12 was converted from the amic ester C-T12 in solvent (pyri-
dine/toluene, Volume ratio: 1:5) by intramolecular dealcoholizing
condensation under feeblish alkalinity condition. And the state of
compound BI-C-T12 took on evenly graininess solid via the new
and succinct step, compared to that of traditional means of diimide
[16].
2.2.1.7. 1,4-Bis[(3,4,5-tridecyloxyphenyl)-dihydrazide]-2,5-diet-
hylphthalate (C-T10). White powder (yield 59%, mp 214–215 °C).
1H NMR (CDCl3 ppm from TMS, 300 MHz) 10.70 (s, 2H), 10.60 (s,
2H), 7.86 (s, 2H), 6.97 (s, 4H), 4.24-4.26 (q, 4H), 3.92 (t, 2H,
J = 6.0 Hz), 3.67 (t, 4H), 1.67-1.79 (m, 12H), 1.26-1.47 (m, 90H),
0.88 (t, 18H, J = 4.5 Hz).
FT-IR (KBr disc cmꢀ1) 3311, 3178, 2954, 2923, 2870, 2852, 1730,
1670, 1603, 1579, 1498, 1456, 1383, 1338, 1299, 1238, 1173, 1118,
1046, 1020, 986, 916, 842, 763, 721, 664, 595.
Anal. Calcd for C88H146N4O14: C, 71.26%; H, 9.85%; N, 3.78%.
Found: C, 71.52%; H, 10.14%; N, 3.57%.
2.2.1.8. 1,4-Bis[(3,4,5-tridodecyloxyphenyl)-dihydrazide]-2,5-diet-
hylphthalate (C-T12). White powder (yield 53%, mp 190–191 °C).
1H NMR (CDCl3 ppm from TMS, 300 MHz) 10.37 (s, 2H), 10.15 (s,
2H), 7.96 (s, 2H), 7.01 (s, 4H), 4.28-4.30 (q, 4H), 3.95 (t, 2H,
J = 6.0 Hz), 3.78 (t, 4H), 1.61-1.72 (m, 12H), 1.26-1.47 (m, 114H),
0.88 (t, 18H, J = 4.5 Hz).
3.2. Self-assembly of hydrazide derivatives
The organogelation property of the hydrazide derivatives were
tested in several solvents and the minimum gel concentration
(MGC) of both C-Tn and BI-C-T12 in benzene, 1,2-dichloroethane
and chloroform were listed in Table 1. Compared with that of BI-
C-T12, C-Tn showed lower MGC indicating that C-Tn’s are more
effective as gelators than BI-C-T12. The MGCs of C-Tn’s decreased
with the increase of length of the terminal alkyl chains, suggesting
that C-Tn with longer terminal chains possessed better gel ability.
To obtain visual insights into the aggregation mode of these
gelators in organogels, the image observation of the xerogels was
performed on a field emission scanning electron microscopy (FE-
SEM). Fig. 1 shows the SEM images of the xerogels of C-T12 and
BI-C-T12 from 1,2-dichloroethane. It can be seen that the SEM im-
age of C-T12 xerogels consists of bundles of fibers which are entan-
gled to for network which are responsible for sustaining the
solvents therein. The fiber diameters are 100 nm. Formation of long
fibers indicates that strong directional intermolecular interaction
FT-IR (KBr disc cmꢀ1) 3313, 3178, 2954, 2922, 2851, 1730, 1672,
1603, 1579, 1497, 1457, 1388, 1339, 1300, 1241, 1119, 1045, 1017,
895, 842, 721, 663, 538.
Anal. Calcd for C100H170N4O14: C, 72.73%; H, 10.30%; N, 3.39%.
Found: C, 72.91%; H, 10.45%; N, 3.05%.
2.2.1.9. 1,4-Bis[(3,4,5-tricetyloxyphenyl)-dihydrazide]-2,5-diet-
hylphthalate (C-T16). White powder (yield 48%, mp 174–175 °C).
1H NMR (CDCl3 ppm from TMS, 300 MHz) 10.01 (s, 2H), 9.78 (s,
2H), 8.04 (s, 2H), 7.03 (s, 4H), 4.31–4.33 (q, 4H), 3.96 (t, 2H,
J = 3.0 Hz), 3.86 (t, 4H), 1.62–1.73 (m, 12H), 1.26–1.35 (m, 162H),
0.87 (t, 18H, J = 7.5 Hz).
FT-IR (KBr disc cmꢀ1) 3183, 2984, 2918, 2870, 2850, 1728, 1670,
1603, 1579, 1498, 1468, 1426, 1383, 1337, 1300, 1239, 1174, 1123,
1046, 1016, 985, 969, 917, 842, 770, 720, 663, 593.
Anal. Calcd for C124H218N4O14: C, 74.92%; H, 10.98%; N, 2.92%.
Found: C, 74.99%; H, 10.99%; N, 2.52%.
Table 1
2.2.2. Synthesis of N0,N0-bis[3,4,5-tris(dodecyloxy)benzamido]-
pyromellitic diimide (BI-C-T12)
Compound C-T12 (1.81 g, 0.01 mol) was dissolved in 150 mL
pyridine/toluene (1:5, V/V) and stirred at 80 °C for about 96 h.
The superfluous solvent was evaporated from the reaction mixture,
then cooled residue was poured into 150 mL water and product
was collected through filtration and dried completely. The product
The minimum gel concentrations (MGC) of C-Tn and BI-C-T12
Solvent
MGC (wt%)
C-T7
C-T10
C-T12
C-T16
BI-C-T12
Benzene
1,2-Dichloroethane
Chloroform
2.21
1.96
Solution
1.94
1.62
1.85
1.54
1.48
1.69
1.51
1.45
1.63
3.06
2.28
Solution

X.-b. Zhang, M. Li / Journal of Molecular Structure 892 (2008) 490–494
493
Fig. 1. FE-SEM images of C-T12 (a) and BI-C-T12 (b) xerogels from 1,2-
dichloroethane.
might exist, which are the driving forces for the self-assembly of
the molecules.
In order to explore the driving forces for the self-assembly of
the molecules, Fourier-transform infrared (FT-IR) and concentra-
tion dependent 1H NMR spectroscopic experiments were
performed.
Fig. 2. FT-IR spectra of C-T12 (a) and BI-C-T12 (b) xerogels from 1,2-
dichloroethane.
The formation of elongated fiber-like aggregates indicates that
the self-assembly of C-T12 is driven by strong directional intermo-
lecular interactions. To ascertain whether hydrogen bonding plays
a role in the gelation process, FT-IR spectrum of the C-T12 organo-
gel was examined. The presence of –N–H stretching vibrations at
3175 cmꢀ1 and –C@O stretching vibrations at 1670 cmꢀ1 for C-
T12 in the gel state unambiguously suggested that the hydrogen
bonding through –N–H. . .O@C– exists in the gelation process. As
are the –N–H and –C@O stretching vibrations for BI-C-T12 in the
gel state (as seen in Fig. 2).
The hydrogen bonding was further confirmed to be the inter-
molecular one through the 1H NMR studies. These results strongly
indicated that –N–H groups were exclusively involved in intermo-
lecular hydrogen bonding [17] and play an important role in the
gelation process. In the 1H NMR dilution studies, the amidic pro-
tons of compounds C-Tn showed a strong concentration depen-
dence, for example, reducing the concentration of C-T12 in CDCl3
from 10ꢀ1M to 10ꢀ2 M causes both NH-1 (near to alkoxy phenyl,
Fig. 3. Set of partial 1H NMR spectra of C-T12 in different concentration CDCl3 at
room temperature (300 MHz): (a) 10ꢀ1 M, (b) 5 ꢁ 10ꢀ2 M, (c) 10ꢀ2 M. The inset
represented half molecular structure of C-T12.
D
d = 1.00 ppm) and NH-2 (near to central phenyl, Dd = 0.84 ppm)
to shift upfield remarkably (as seen in Fig. 3), which strongly indi-
cates that the two amide protons in C-T12 participate in intermo-
lecular hydrogen bonding.
Furthermore, the antisymmetric (
stretching vibrational modes of C-Tn are utilized to probe alkyl
mas) and symmetric (ms) CH2

494
X.-b. Zhang, M. Li / Journal of Molecular Structure 892 (2008) 490–494
Table 2
Summary of –CH2– stretching vibrations of hydrazide derivatives in xerogels
Assignments
IR frequencies (cmꢀ1
)
C-T7 xerogel
C-T10 xerogel
C-T12 xerogel
C-T16 xerogel
BI-C-T12 xerogel
m
m
as(CH2)
s(CH2)
2924
2853
2923
2852
2922
2851
2929
2859
2921
2851
chain conformations. With the end-on alkyl chain length prolong-
ing, for C-Tn xerogel (except for C-T16 [18]), the as(CH2) and
s(CH2) appear in the ranges of 2921–2924 and 2851–2853 cmꢀ1
forces for the formation of self-assembled gel. Furthermore, the
longer the end-on attached alkyl chains, the stronger the gelation
ability.
m
m
(Table 2), indicating a significant population of the trans conforma-
tion [19]. The lower wavenumber shift reveals a decrease in the
fluidity of the alkyl chains due to the strong organization of the al-
kyl groups via van der Waals interaction. Consequently, the driving
forces for organogelation followed by entanglement of the self-
assembled nanofibers are mainly hydrogen bonding and van der
Waals interactions.
In many cases, organogelations need a heating dissolution pro-
cess. The organogels show the same structural properties (FT-IR
and 1H NMR) as those made by the hydrazide derivatives and the
same gel properties such as the thermoreversibilities. Furthermore,
this procedure can apply for some solvents that gelators C-Tn and
BI-C-T12 can gel, as shown in Table 1. In summary, we revealed the
effects of hydrogen bonding and van der Waals forces on the orga-
nogelation using new hydrazide-based gelators with various num-
bers of hydrogen bonding sites as well as alkyl chain lengths and
the organogel formation at room temperature. For the hydrazide-
based organogelators, gelator C-T12 possessing the four potential
hydrogen bonding sites and dodecyl groups at both terminals has
the best organogelation ability. Using 1,2-dichloroethane and ben-
zene as the vectors for organogelators C-Tn and BI-C-T12 playing
their roles, organogelation at room temperature can be achieved.
Acknowledgments
This work was supported by the National Science Foundation
committee of China (Project No. 50373016), Program for New
Century Excellent Talents in Universities of China Ministry of
Education, Special Foundation for PhD Program in Universities
of China Ministry of Education (Project No. 20050183057), and
PhD Foundation of Henan Polytechnic University (Project No.
67648271).
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4. Conclusions
Based on the SEM observations, FT-IR and 1H NMR spectroscopy
methods, we studied the self-assembly of the hydrazide com-
pounds C-Tn and BI-C-T12 in solution. Investigating the minimum
concentrations of gelling, aggregation morphology and structure of
gels, and gelation driving forces, the results showed, (1) intermo-
lecular hydrogen bonding origining from –C@O group and –N–H
group existed in hydrazide compounds C-Tn and BI-C-T12, respec-
tively, and it could freeze organic solvent forming gel; (2) the
change of the number of hydrogen bonding donor-acceptor and
the lengths of alkyl chains of hydrazide derivatives affected gelling
ability remarkably, it indicated that intermolecular hydrogen
bonding and van der Waals interactions were the main driving
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