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Xylitol based phase selective organogelators for
potential oil spillage recovery†
Cite this: RSC Adv., 2017, 7, 37175
*
Chinthalapati Siva Kesava Raju,
Bhaskar Pramanik, Raman Ravishankar,
Peddy Venkat Chalapathi Rao and Gandham Sriganesh
Received 20th June 2017
Accepted 20th July 2017
Xylitol based phase selective organogelators are developed for crude oil of varying API gravity and various
petroleum fractions/oils. Intermolecular hydrogen bonding was responsible for gel formation with three
dimensional cross linked networks. Efficient gelation at room temperature, high mechanical strength, oil
recovery and gelator reusability make these compounds promising candidates for oil spill mitigation.
DOI: 10.1039/c7ra06898k
rsc.li/rsc-advances
Water pollution has become a serious problem for mankind in pharmaceuticals, bio-technology, light harvesting, lubricants
the 21st century.1 There are a number of ways by which water is and food industry.16–19 LMWGs that can selectively solidify oils
being polluted in which oil spillage, a result of accidental or from oil–water biphasic mixture at room temperature (phase-
intentional release of petroleum products in the environment, selective gelators, PSGs) have become popular and demanding
is one route.2,3 The world has witnessed several oil spillage as ideal solidifying material for oil spill recovery.7,8 Since the
incidents and one of the major incidents in recent time is the 5 rst report of PSG by Bhattacharya and co-workers with alanine-
billion barrels of crude oil release in the Gulf of Mexico.4 The based amphiphile20 there are several reports regarding phase
adverse effects of oil spillage are observed on marine ecosys- selective gelator molecules. The ideal PSGs for oil spill recovery
tems and the economy associated with spilled oil mitigation.5 must full some requirements such as: (a) cost effective and
Conventional methods for oil spill recovery include combus- easily synthesizable (b) selective and efficient gelation of oil
tion, mechanical treatment using oil sorbent materials, chem- phase, (c) rapid gelation at room temperature, (d) stable gel with
ical treatment by dispersants, and bioremediation with respect to temperature and external force, (e) easy oil recovery
microorganisms.6 All of these processes are associated with from the gel phase, and (f) reusable.
certain drawbacks like poor recovery, release of toxic residues,
Aiming for various applications, a wide range of molecular
being uneconomical, time consuming etc. Recently low mole- building blocks like peptides, sugars, paraffinic alcohols,
cule organogelators (LMWGs) have gained immense interest as nucleo-bases, acids, steroids, ureas are used for LMWG
an alternate to mitigate oil spills.7–9
synthesis and gel formation.12,20–40 Sugar based gelators are one
LMWGs having molecular weight <2000 Da can translate to of the important class from economic perspective, ease of
three dimensional brillar networks in presence of suitable synthesis and biocompatibility.27–46 John and co-workers in 2010
solvent via intermolecular self-assembly.10,11 The nono-scale or demonstrated a model study with reduced sugar (mannitol)
micro-scale network structure are formed by non-covalent based amphiphile PSGs for oil spill treatment.29 Following the
interactions like hydrogen bonding, p–p stacking, van der pathway of selective protection of hydrophilic –OH groups in
Walls interactions, dipole–dipole interactions, charge transfer sugars by hydrophobic groups, several authors have reported
interactions.12 Apart from internal forces external conditions mannitol,29–33 sorbitol,34–37 glucose,38–40 galactose,41,42 arabi-
like heating–cooling cycle, solvent change, sonication, analyte nose43,44 and other sugar based PSGs.45,46 But, xylitol based
addition, pH change, light and oxidation/reduction etc. govern phase selective gelator is not reported so far. In general,
gel formation.13,14 Gels are solid-like network in liquid-like synthesis of sugar based PSGs follow protection of the hydroxyl
medium which can display the rheological properties of solid- groups by hydrophobic groups and based on the degree of
phase materials, high surface area for liquid phase and rapid protection the nal compound may be oil selective or water
internal diffusion kinetics for self healing.15 These distinct selective. The distinct feature of these kind of sugar based
properties of gel dictates vast range of applications in catalysis, gelators is that carbohydrate part is capable of forming
hydrogen bonding to allow various self assembled structures
and hydrophobic groups promote the building blocks by p–p
Analytical Division, Hindustan Petroleum Green R&D Center (HPGRDC), KIADB stacking and van der Waals interactions.27,45,46 Sugar based
Industrial Estate, Tarabahalli, HoskoteTaluk, Bangalore, 560067, Karnataka, India.
gelators, reported so far are effective for phase selective gelation
of solvents and various oils such as petrol, diesel, kerosene, etc.
E-mail: cskraj@hpcl.in
† Electronic supplementary information (ESI) available: Synthetic procedure,
in presence of water. However, the major oil-spills caused by
gelation video. See DOI: 10.1039/c7ra06898k
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Table 1 Gelation abilities of compounds 1–3 in different hydrocarbon
crude-oil, mainly during transportation through sea or during
drilling which is associated with more rigorous challenge for
recovery, are mitigated by sugar based gelators; are reported by
very few authors.33,39,43,44 As already discussed earlier that heat-
ing–cooling process is tedious and not viable over sea. Room
temperature gelation is preferred choice for these type of typical
applications. Recent literatures indicate the mitigation of crude
oil spills by sugar based gelators, applying them in solution
phase or as powder at room temperature.33,39,43,44 Regardless of
some recent progress in the eld, there is still a signicant need
to develop many more examples of cost effective, less toxic and
easily applicable LMWGs to handle the real situation of
a marine oil spill.
Inspired by the progress of research work in the area of
sugar-derived LMWGs,27,28 sugar based compounds having
hydroxyl groups to support hydrogen bonding, aromatic part
and alkyl chain to favor oil phase gelation are developed in this
present work. In this paper, xylitol based organogelators have
been reported capable of gelating a series of organic solvents,
mineral oils, crude oils and edible oils. Phase selective oil
solventsa
1
2
3
Solvent
system
MGC
(% w/v)
MGC
(% w/v)
MGC
(% w/v)
MUC
MUC
MUC
Hexane
Octane
P
P
P
P
P
P
—
—
P
P
—
—
Dodecane
Hexadecane
Benzene
Toluene
Xylene
CRN
SRN
Kero
Diesel
1.8
55
60
86
89
95
93
76
161
232
59
153
1.91
1.75
1.22
1.2
1.2
1.28
P
1.1
0.62
1.85
0.78
52
57
81
83
83
78
—
90
161
54
128
P
—
1.65
1.16
1.12
1.05
1.07
1.31
0.62
0.43
1.69
0.65
1.9
1.43
1.37
1.35
P
52
69
72
74
—
P
—
1.84
0.77
2.01
0.92
54
129
49
108
Crude oil
Vegetable oil
a
MGC ¼ Minimum Gelation Concentration (amount in g of gelator
required for 100 ml of hydrophobic material to be gelated), MUC ¼
Minimum Uptake Capability (volume in ml of hydrophobic material
phase gelation from oil–water mixture at room temperature gelated by 1 g of gelator), P ¼ Precipitate.
followed by recovery of both oil and gelator are also presented
(Scheme 1).
The gelator compounds were synthesized in a single step by
Aer performing the gelation experiment of the compounds
acid catalyzed reaction between xylitol and aromatic aldehyde/
ketone in a biphasic system comprise of methanol and cyclo-
hexane. Enhanced solubility of the product in cyclohexane than
methanol favour the reaction going forward and white solid
products were obtained in 64 to 90% yields.
for different solvents they were subjected for different oils,
especially renery distillates as well as crude oil and vegetable
oil. The results are provided in the Table 1. All three gelators
were capable in transforming different oils into gel phase with
different MGC values ranging from 0.43 to 2% w/v. Crude oil
with complex composition had least gelation tendency than its
different fractions. Minimum uptake capability for crude oil
was found to be in between 49 to 59 times whereas the
maximum gelation ability was observed for diesel (upto 232
times). Poor gelation ability of the compounds with paraffinic
solvents is reected in their gelation ability with renery
distillates too. Straight Run Naphtha (SRN) having least
aromatic content than other distillates had the lowest gelation
efficiency than others; even gelator 2 and 3 was unable to form
gel with SRN. Cracked Naphtha (CRN) having higher percentage
of unsaturates e.g. olens and aromatics was gelated easily than
SRN. Moving from lighter fractions to heavier fractions (i.e. SRN
to Diesel via Kero cut) aromatic content gradually increases
resulting successive increment of gelation ability. Thus combi-
nation of molecular weight factor and aromatic content factor
leads to the observation that heavier oil fraction is easily gelated
than the lighter one. Comparison of gelation ability of 1–3 for
crude oil as well for other oils dictates superior gelation ability
of 1 followed by 2 and 3. Apart from petroleum oils, vegetable oil
was also converted to gel, exhibiting minimum uptake capa-
bilities ranging from 108 to 153 times.
Gelation ability of three xylitol based compounds in different
solvents and oils are tested and the results are represented in
Table 1. The table infer that all these compounds have poor
gelation abilities towards paraffinic solvents, whereas they are
quite efficient for aromatic solvents. Minimum uptake capa-
bilities of 1–3 towards aromatic solvents vary in between 70 to
95 times and that for paraffinic solvents it's in between 50 to 60
times. Superior efficiency of 1–3 for aromatic solvents than that
for paraffinic solvents might be due to the presence of aromatic
hydrophobic part in these gelator compounds coming from two
protecting aromatic groups. They all are unable to convert low
molecular weight paraffinic solvents e.g. hexane and octane to
obtain their respective gel however, heavier paraffinic solvents
i.e. hexadecane and dodecane can be converted to gel. Thus,
higher the molecular weight of the paraffinic solvent lower is
the MGC. The same trend is followed for aromatic solvents too.
Another observation can be made from the table that gelation
ability of these compounds toward aromatic as well as paraffinic
solvents decreases from 1 to 3. This phenomenon can be
attributed to the increasing hydrophobicity in the alkyl side
chain from compound 1 to 3.
Among the different oils that are studied for gelation, crude
oil was chosen as model for oil spill recovery experiment. Crude
oil being a complex mixture of thousands of hydrocarbons as
well as metal impurities is always challenging for gelation
studies. Again based on the nature of hydrocarbons present in
crude oil its property varies drastically for different crude oils.
Scheme 1 Synthetic scheme of the gelator compounds 1–3.
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attributed to the successive increment of resins & asphaltene
content in crude oil. The lightest crude of our study (API 40.5)
didn't follow the same trend and gelation ability found to be
inferior to that of adjacent lighter crude. This observation may
be due to the higher paraffinic content in the extra light crude
(C5) reecting the poor gelation capability of 1–3 for paraffinic
solvents. This infers that more than API the constituents
present in the crude will dictate the gelation. These experiments
infer that xylitol sugars are effective as gelators for different
Fig. 1 Photographs of gels with different oils in a biphasic mixture with crudes covering the wide spectrum of crude basket available
water (CuSO4 solution results blue colour of the aqueous phase).
from different parts of the globe.
As the prime focus was on oil spillage recovery, the gelators
are required to be effective for selective oil phase gelation
without gelating the aqueous phase from oil–water biphasic
mixture. Six oil samples containing crude oil, renery distillates
as well as vegetable oil were subjected for phase selective gela-
tion. Experimental results are given in Table 2 and represented
in Fig. 1. All three gelators were able to gelate exclusively the oil
phase without altering the water phase during performance
evaluation gelation experiments. Gelation abilities of the gela-
tors followed the same order as reported in Table 1 i.e. gelation
ability trend is 1 > 2 > 3. Selective gelation revealed that MGCs
for all oils were increased very slightly from their respective
Fig. 2 Gelation by 1–3 with different crude oils–water biphasic
mixture denoted by C1 to C5 (C1: API 18.8, C2: API 27.1; C3: API 28.1,
C4: API 35.5; and C5: API 40.5).
individual/single phase studies might be due to partial solu-
bility of the gelators in aqueous phase as observed earlier.31
Considering the practical application of oil spill recovery, effect
of water salinity over gelation ability was crosschecked by using
sea water in the biphasic mixture. The data from Table 2 inform
the similarity of gelation abilities i.e. similar MGC & MUC values
in sea water to that of normal water. Thus, ability of the orga-
nogelators towards gelation for oil phase is highly encouraging
even under extreme conditions revealing practical application
towards oil spillage recovery over sea.
There are a number of processes that can be applied for
phase selective gelation of oil phase. Those most commonly
used processes are (a) dissolution of the phase selective gelator
in oil by heating and cooling to form gel,42 (b) dissolution of the
gelator in soluble solvents e.g. alcohols, ethers at room
The effect of the composition of crude oil on the gelation ability
of 1–3 were performed with different crudes of varying API
gravities ranging from very low API (C1, 18.8ꢀ) to high API (C5,
40.5ꢀ). Fig. 2 demonstrate the effect of crude oil API density over
the gelation property of xylitol based gelators. Minimum uptake
capabilities ranging from 40 to 60 times for various crude oils
are quite remarkable regarding their compositional complex-
ities. The heavy crude (lower API) exhibited higher MGC and
lighter crude (higher API) exhibited lower MGC and the uptake
capability decreased with increase in API gravity. Thereby
a reduction in the uptake capacity with lowering API may be
Table 2 Gelation abilities of compound 1–3 in various biphasic mixturesa
1
2
3
Solvent system
MGC (% w/v)
MUC
MGC (% w/v)
MUC
MGC (% w/v)
MUC
CRN–water
SRN–water
1.2
1.4
83.3
71.4
1.31
P
76.3
—
P
P
—
—
Kero–water
Diesel–water
Crude–water
Veg oil–water
CRN–sea water
SRN–sea water
Kero–sea water
Diesel–sea water
Crude–sea water
Veg oil–sea water
0.65
0.5
1.8
0.7
1.2
1.38
0.65
0.48
1.81
0.7
153.8
200
55.5
142.8
83.3
72.4
153.8
208.3
55.2
1.17
0.73
1.96
0.81
1.35
P
85.4
136.9
51.0
123.4
74.07
—
83.3
133.3
51.2
125
1.85
0.8
2.05
0.98
P
54.0
125
48.7
102.0
—
P
—
1.2
1.85
0.82
2.1
1.0
54.0
121.9
47.6
100
0.75
1.95
0.8
142.8
a
MGC ¼ Minimum Gelation Concentration, MUC ¼ Minimum Uptake Capability, P ¼ Precipitate.
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taken in a glass tray was made and DCM solution was added to
it. As shown by ESI video,† SRN layer was transformed in gel
that was collected from the water surface by scooping for further
recovery of oil. The effectiveness of gelator towards the recovery
of oil from gel phase was performed showing 97% oil recovery.
The gel can be reused for more than 5 times with recovery up to
90% with renery fractions. Similar experiment with crude oil
ꢀ
exhibited oil recovery of 53% upto boiling point of 350 C. As
crude oil is complex and nal boiling point can be more than
700 ꢀC, recovery of gel from crude oil is difficult process. Also gel
contains mainly hydrocarbons with oxygenated compounds,
hence oil gel can go as feed with Fluidised Catalytic Cracking
(FCC) unit.
Fig. 3 FT-IR spectra of gelator 1, in chloroform and xerogel obtained
from diesel.
FT-IR spectroscopy gave the information about non-covalent
interactions involved in gelation process (Fig. 3). As discussed
earlier that hydrogen bonding interaction plays an important
role, which can be observed from FT-IR study.15 The FT-IR
spectra of 1 in non-gelating solvent chloroform didn't change
from its solid state i.e. the broad peak at 3294 cmꢁ1 for –OH
group remained unchanged signifying no hydrogen-bonded
aggregation in a non-gelating solvent. However in the diesel
gel of 1, the peak at 3294 cmꢁ1 shied to 3250 cmꢁ1 with
increased intensity, which conrms the presence of intermo-
lecular hydrogen bonding network involved in gel formation.30
The morphology study of the supramolecular organogels was
carried out by scanning electron microscopy (SEM) and Fig. 4
represents the SEM images in various oils by compound 1. The
SEM images from various petroleum fractions revealed the
formation of self-assembled brillar networks and different
textures were obtained from different oils. Three dimensional
brous networks in diesel are denser than that of the others.
The ber length was several micrometers having cross linking
dimension of few nanometers. The SEM image of xerogel from
CRN–gel and SRN–gel also conrmed the presence of brous
bundled network with increasing ber chain length and width.
The presence of hydrogen bonding is believed to be the driving
force for such three dimensional cross-linked ber assembly
which was proved earlier also from FT-IR study. Thus –OH
group present in each molecule, by involving in intermolecular
hydrogen bonding leads to self-assembled brillar networks
where entrapped solvent molecules may result as the supra-
molecular gel.
temperature and adding the solution over oil,29,32,38 (c) dissolu-
tion of the gelator in the same liquid that to be gelated or in
a suitable water immiscible solvent by heating having solution
concentration much higher than MGC to spray over biphasic
mixture under hot condition,25,26,31,33,43,44 (d) applying xerogels
i.e. dried gels.39 Some limitations are associated with these
processes like heating–cooling cycle for process-A is practically
impossible on the sea level, water miscible solvents for process-
B are environmental hazard for marine lives, uneconomical
heating and use of more amount of gelator to congeal oil along
with the carrier solvent is associated with process-C whereas
poor efficiency of xerogels limits their application for process-D.
Such limitations can easily be removed using the gelator in
solid state at room temperature without using any solvent and/
or heating as reported by Sureshan et al.39 Application of
compounds 1–3 in solid state as powder didn't exhibit any
gelation process which drove us to nd an alternate way of
application. Room temperature phase selective gelation was
experimented by dissolving the gelators in oil immiscible
solvent toluene. In a typical procedure 10% solution of the
gelator was prepared by dissolving it in toluene and the mixture
is heated gently to make it as solution. To a 25 ml of crude oil
layer over 100 ml of sea water the gelator solution was applied to
ensure complete dispersion. Within a 2 minutes the crude oil
layer is transformed to the gel state. Thus, utilizing the toluene,
phase selective gelation of crude oil as well as other oil fractions
are possible.26 Gelation time observed for renery fractions like
naphtha, kerosene and diesel are found to be less than 1
minute. However, vegetable oil and crude oil gelation have
taken more than 2 minutes for proper gelation because of the
complexity.
Stability and strength of the gels were studied as practical
application of the gelators for oil recovery requires structural
In order to exhibit the application of these gelators in oil spill
recovery, a model oil spill set-up by adding SRN to sea water
Fig. 5 Dynamic rheology of the organogels obtained from different
Fig. 4 SEM images of xerogels by 1 obtained from SRN, diesel and oils: (A) as a function of angular frequency and (B) as a function of
CRN.
oscillatory stress at 25 ꢀC.
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integrity of the gels under harsh condition for a longer period of the protecting carbonyl compound where hydrophobicity
time. Stability of the gels was found to be very high, oating over increases from compound 1 to 3. Increasing hydrophobicity had
the aqueous layer for several weeks without deteriorating the inverse effect on their gelation ability. Gelation result for
gels.
specic oil by 1–3 as well as mechanical strength revealed the
Mechanical strength of the organogels was studied by gelation efficiency to follow the order 1 > 2 > 3.
rheology experiments in oscillatory mode. Both frequency
sweep and amplitude sweep experiments were performed to
deduce two main parameters namely storage modulus (G0) and
loss modulus (G00). The elastic modulus G0 in frequency sweep
Notes and references
experiment of the gels as shown in Fig. 5, is much higher than
the viscous modulus G00 where both parameters are indepen-
dent of frequency in the frequency range of 5–500 rad sꢁ1. This
observation is typical for the viscoelastic gel behaviour as the gel
state is signied by G0 > G00 and in the sol state is signied by G0 <
G00; where G0 corresponds to the ability of the deformed material
to store energy and G00 signies the ow behaviour of the
material under stress.29,39,44 The storage modulus value in the
order of 103–104 Pa indicates strong gel state to be retained
when a small strain was imposed. The highest storage modulus
was observed for diesel gel by 1; can be correlated to the lower
MGC and better cross-linking by SEM image. Crude oil gel by 1
had better mechanical strength than SRN gel as expected from
MGC values in Table 1. Oscillatory sweep experiments were also
carried out to indentify gel–sol transition point. Applying
a signicant shear strain to the gel and its arranged structure
1 WHO/UNICEF, Investing in water and sanitation: Increasing
access, reducing inequalities, World Health Organization,
Geneva, 2014.
2 M. Fingas, Handbook of Oil Spill Science and Technology,
Wiley, US, 2015.
3 L. Guterman, Science, 2009, 323, 1558.
4 On Scene Coordinator Report on Deepwater Horizon Oil
Spill,
2011,
http://www.uscg.mil/foia/docs/dwh/
fosc_dwh_report.pdf.
5 Y. Gong, X. Zhao, Z. Cai, S. E. O'Reilly, X. Hao and D. Zhao,
Mar. Pollut. Bull., 2014, 79, 16.
6 D. Dave and A. E. Ghaly, Am. J. Environ. Sci., 2011, 7, 423.
7 B. O. Okesola and D. K. Smith, Chem. Soc. Rev., 2016, 45,
4226.
8 K. Liu, P. He and Y. Fang, Sci. China: Chem., 2011, 54, 575.
9 Y. Ohsedo, Polym. Adv. Technol., 2016, 27, 704.
can be destroyed; identied by the crossover point of G0 and G00 10 Molecular Gels: Materials with Self-Assembled Fibrillar
(Fig. 5) and G00 > G0 condition is in accordance with the sol-like
owing state.33 Fig. 5 revealed the gelation ability trend of 1 > 2 >
Networks, ed. R. G. Weiss and P. Terech, Springer,
Dordrecht, Netherlands, 2006.
3 with respect to the mechanical strength of their diesel gels 11 P. Terech and R. G. Weiss, Chem. Rev., 1997, 97, 3133.
and the crossover point of G0 and G00.
12 J.-L. Li and X.-Y. Liu, Adv. Funct. Mater., 2010, 20, 3196.
In conclusion, C5-reduced sugar based xylitol was utilized to 13 M. D. Segarra-Maset, V. J. Nebot, J. F. Miravet and B. Escuder,
synthesis small molecule organogelators 1–3 by selectively Chem. Soc. Rev., 2013, 42, 7086.
protecting the hydroxyl groups with carbonyl compounds. The 14 P. Dastidar, Chem. Soc. Rev., 2008, 37, 2699.
synthesized amphiphilic compounds exhibited phase selective 15 S. Yu, L. Chen, M. Zhang and T. Yi, Chem. Soc. Rev., 2014, 43,
gelation of hydrophobic solvents or oils in presence of aqueous
phase. Aromatic solvents were easily transformed into gel, using 16 N. M. Sangeetha and U. Maitra, Chem. Soc. Rev., 2005, 34,
the gelators having aromatic protecting group in their structure,
821.
than the paraffinic solvents; again heavier paraffinic hydrocar- 17 S. Banerjee, R. K. Das and U. Maitra, J. Mater. Chem., 2009,
bons were easy to form gel than the lighter hydrocarbons. 19, 6649.
Effectiveness of the gelators was not only limited to common 18 A. R. Hirst, B. Escuder, J. F. Miravet and D. K. Smith, Angew.
solvents but also observed for a large number of renery Chem., Int. Ed., 2008, 47, 8002.
distillates along with crude oil. Complexity of crude oil limited 19 K. J. Skilling, F. Citossi, T. D. Bradshaw, M. Ashford,
the gelation efficiency around 50 times whereas heavier mineral
B. Kellam and M. Marlow, So Matter, 2014, 10, 237.
oils exhibited much higher gelation efficiency (i.e. MUC ¼ 232 20 S. Bhattacharya and Y. Krishnan-Ghosh, Chem. Commun.,
for diesel by 1) than the lighter oils (i.e. MUC ¼ 76 for SRN by 1).
2001, 0, 185.
Successful demonstration of the gelation process for various 21 C. Tomasini and N. Castellucci, Chem. Soc. Rev., 2013, 42,
crude oils with varying densities covering almost the entire 156.
crude basket, inferred the applicability of 1–3 for the mitigating/ 22 S. Debnath, A. Shome, S. Dutta and P. K. Das, Chem.–Eur. J.,
containing the oil spillage. Recovery of oil from gel phase was 2008, 14, 6870.
also demonstrated to emphasize on applicability of the gelators. 23 (a) S. Basak, J. Nanda and A. Banerjee, J. Mater. Chem., 2012,
5346.
Mechanical strength of the gels; an important parameter to
collect gels over aqueous layer for oil recovery, was remarkable
as a consequence from three dimensional network. FT-IR and
22, 11658; (b) D. K. Maiti and A. Banerjee, Chem.–Asian J.,
2013, 8, 113; (c) A. K. Das, P. P. Bose, M. G. B. Drew and
A. Banerjee, Tetrahedron, 2007, 63, 7432.
SEM studies concluded the presence of strong intermolecular 24 T. Kar, S. Debnath, D. Das, A. Shome and P. K. Das,
hydrogen bonding for self-assembled brillar network being Langmuir, 2009, 25, 8639.
the prime factor for the gel formation. Compounds 1–3 differ in 25 C. Ren, G. H. B. Ng, H. Wu, K.-H. Chan, J. Shen, C. Teh,
the alkyl chain [R ¼ –H (1), –Me (2) and –Et (3)] associated with
J. Y. Ying and H. Zeng, Chem. Mater., 2016, 28, 4001.
This journal is © The Royal Society of Chemistry 2017
RSC Adv., 2017, 7, 37175–37180 | 37179

View Article Online
RSC Advances
Paper
26 C. S. K. Raju, B. Pramanik, T. Kar, P. V. C. Rao, 37 C. Tong, K. Fan, L. Niu, J. Li, X. Guan, N. Tao, H. Shen and
N. V. Choudary and R. Ravishankar, RSC Adv., 2016, 6, 53415. J. Song, So Matter, 2014, 10, 767.
27 S. Datta and S. Bhattacharya, Chem. Soc. Rev., 2015, 44, 5596. 38 S. Mukherjee, C. Shang, X. Chen, X. Chang, K. Liu, C. Yu and
28 B. O. Okesola, V. M. P. Vieira, D. J. Cornwell, N. K. Whitelaw
and D. K. Smith, So Matter, 2015, 11, 4768.
29 S. R. Jadhav, P. K. Vemula, R. Kumar, S. R. Raghavan and
G. John, Angew. Chem., Int. Ed., 2010, 49, 7695.
30 A. Vidyasagar, K. Handore and K. M. Sureshan, Angew.
Chem., Int. Ed., 2011, 50, 8021.
Y. Fang, Chem. Commun., 2014, 50, 13940.
39 (a) A. M. Vibhute, V. Muvvala and K. M. Sureshan, Angew.
Chem., Int. Ed., 2016, 55, 7782; (b) A. Prathap,
K. M. Sureshan, Angew. Chem., Int. Ed., DOI: 10.1002/
anie.201704699.
40 S. Roy, A. Chakraborty and R. Ghosh, Carbohydr. Res., 2008,
343, 2523.
41 O. Gronwald and S. Shinkai, Chem.–Eur. J., 2001, 7, 4328.
31 A. Prathap and K. M. Sureshan, Chem. Commun., 2012, 48,
5250.
32 J. Gao, K. Feng, H. Li, Y. Jiang and L. Zhou, RSC Adv., 2015, 5, 42 S. Mukherjee and B. Mukhopadhyay, RSC Adv., 2012, 2, 2270.
68601.
43 Rajkamal, D. Chatterjee, A. Paul, S. Banerjee and S. Yadav,
Chem. Commun., 2014, 50, 12131.
44 Rajkamal, N. P. Pathak, D. Chatterjee, A. Paul and S. Yadav,
RSC Adv., 2016, 6, 92225.
33 M. Samateh, A. Vidyasagar, S. R. Jadhava and G. John, RSC
Adv., 2016, 6, 107598.
34 N. Mohmeyer, P. Wang, H.-W. Schmidt, S. M. Zakeeruddin
¨
and M. Gratzel, J. Mater. Chem., 2004, 14, 1905.
45 S. S. Babu, V. K. Praveen and A. Ajayaghosh, Chem. Rev.,
2014, 114, 1973.
46 L. S. Birchall, S. Roy, V. Jayawarna, M. Hughes, E. Irvine,
G. T. Okorogheye, N. Saudi, E. D. Santis, T. Tuttle,
A. A. Edwards and R. V. Ulijn, Chem. Sci., 2011, 2, 1349.
35 W. Chen, Y. Yang, C. H. Lee and A. Q. Shen, Langmuir, 2008,
24, 10432.
36 S. Grassi, E. Carretti, L. Dei, C. W. Branham, B. Kahr and
R. G. Weiss, New J. Chem., 2011, 35, 445.
37180 | RSC Adv., 2017, 7, 37175–37180
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