Light induced construction of porous covalent organic polymeric networks for significant enhancement of CO2 gas sorption

Article abstract of DOI:10.1039/c7ra09538d

Herein, we report morphology-controlled porous polymeric materials for enhanced CO₂ capture, which was achieved using the topochemical polymerization of dipeptide functionalized diphenylbutadiynes. The topochemical reaction was executed to control the morphology of the synthesized dipeptide appended diarylbutadiyne derivatives on a solid surface. Topochemical polymerization involves the formation of polydiacetylene due to the presence of hydrogen bonding between the amide groups and intermolecular π-π stacking interactions in their self-assembled state, which was established using UV-Vis, Raman and IR spectroscopy. The change in morphology of the two dipeptide functionalized diphenylbutadiyne (DPB) was confirmed by scanning electron microscopy. Porosity was developed after UV irradiation of the diacetylene-based dipeptide appended bolaamphiphiles. Interestingly, after UV irradiation, the porous covalent organic polymers 1 and 2 show 24.22 times and 12 times enhanced N₂ gas adsorption than their parent compounds 1 and 2, respectively. The surface area of the porous covalent organic polymers 1 and 2 was enhanced 21.68 times and 5.54 times than their parent compounds 1 and 2, respectively. Polymer 1 exhibits 4.23 times the CO₂ capture ability than compound 1 and polymer 2 shows 4.1 times the CO₂ capture ability than compound 2. This study highlights the controlled synthesis of light induced porous covalent organic polymers with high surface area used for efficient CO₂ storage applications.

Full text of DOI:10.1039/c7ra09538d

RSC Advances
View Article Online
View Journal | View Issue
PAPER
Light induced construction of porous covalent
organic polymeric networks for significant
enhancement of CO2 gas sorption†
Cite this: RSC Adv., 2017, 7, 47695
*
Soumitra Bhowmik, Maruthi Konda and Apurba K. Das
Herein, we report morphology-controlled porous polymeric materials for enhanced CO2 capture, which was
achieved using the topochemical polymerization of dipeptide functionalized diphenylbutadiynes. The
topochemical reaction was executed to control the morphology of the synthesized dipeptide appended
diarylbutadiyne derivatives on a solid surface. Topochemical polymerization involves the formation of
polydiacetylene due to the presence of hydrogen bonding between the amide groups and intermolecular
p–p stacking interactions in their self-assembled state, which was established using UV-Vis, Raman and
IR spectroscopy. The change in morphology of the two dipeptide functionalized diphenylbutadiyne (DPB)
was confirmed by scanning electron microscopy. Porosity was developed after UV irradiation of the
diacetylene-based dipeptide appended bolaamphiphiles. Interestingly, after UV irradiation, the porous
covalent organic polymers 1 and 2 show 24.22 times and 12 times enhanced N2 gas adsorption than their
parent compounds 1 and 2, respectively. The surface area of the porous covalent organic polymers 1 and
2 was enhanced 21.68 times and 5.54 times than their parent compounds 1 and 2, respectively. Polymer 1
exhibits 4.23 times the CO2 capture ability than compound 1 and polymer 2 shows 4.1 times the CO2
capture ability than compound 2. This study highlights the controlled synthesis of light induced porous
covalent organic polymers with high surface area used for efficient CO2 storage applications.
Received 28th August 2017
Accepted 25th September 2017
DOI: 10.1039/c7ra09538d
rsc.li/rsc-advances
a well-dened molecular architecture with specic shape and
size. The controlled self-assembly of peptide-based amphiphiles
Introduction
has attracted great attention due to their unique architectures,
including bers,20–24 tubes,25–27 spheres,28–31 vesicles32–35 and
cylinders36–38 as well as their applications in drug delivery39,40
and injectable therapy to control hemorrhage.41 Peptide-based
bolaamphiphiles are a unique class of amphiphiles, which
can self-assemble into different architectures through non-
covalent interactions upon the inuence of external
stimuli.42–45 Upon incorporation of a diacetylene moiety into the
peptide backbones, peptide functionalized diacetylene-based
amphiphiles can self-assemble into an oriented fashion and
form self-assembled nanostructures. Peptide-functionalized
diphenylbutadiyne-based bolaamphiphiles can also be poly-
merized using topochemical polymerization if they are appro-
priately oriented. Peptide-functionalized polydiacetylene-based
amphiphiles have been used in several applications such as
chromatic sensors, lipopolysaccharide detectors, biotechnology
and biomedicine.46–48 Peptide-functionalized polydiacetylene-
based amphiphilic bers have also been used to sense cell
adhesion via its colorimetric sensing behaviour upon UV irra-
diation.49 Its self-organization behaviour also changes with
a change in suitable spacer length in the case of diacetylene-
containing peptide bolaamphiphiles.50 Diacetylene containing
peptide bolaamphiphiles have also been used as optoelectronic
In recent years, an enormous amount of greenhouse gases
including CO2 are released into the atmosphere with the earth's
increasing population, which has triggered a rapid increase in
atmospheric temperature.1–5 Inspired by natural zeolite struc-
tures, researchers are working to develop porous materials for
effective CO2 capture. Porous materials, such as covalent
organic polymers (COPs),6–11 metal–organic frameworks
(MOFs)12 and covalent organic frameworks (COFs)13,14 with
miscellaneous properties and applications have attracted great
attention in materials science research. Porous covalent poly-
mers are used as effective CO2 sorption materials due to their
ultra-high hydrothermal stability. Porous COPs are potentially
benecial for gas storage and separation,15 catalysis,16 chemical
sensing, drug delivery,17 electronic devices18 and energy storage
applications.19 However, considerable attention has been
focused on controlling the self-assembly, pore size, surface area
and functionality in nanoporous solids. Precise molecular
self-assembly enables the arrangement of molecules in
Department of Chemistry, Indian Institute of Technology Indore, Indore 453552, India.
E-mail: apurba.das@iiti.ac.in
† Electronic supplementary information (ESI) available: Synthesis details,
spectroscopic data for all synthesized compounds, SEM image, TGA data and
gas adsorption data. See DOI: 10.1039/c7ra09538d
materials.51
The
conducting
poly(diphenylbutadiyne)
This journal is © The Royal Society of Chemistry 2017
RSC Adv., 2017, 7, 47695–47703 | 47695

View Article Online
RSC Advances
Paper
palladium(II) dichloride) were purchased from Alfa Aesar, India.
L-Leucine, L-phenylalanine, L-tyrosine, HOBt (1-hydroxybenzo-
triazole) and DCC (N,N0-dicyclohexylcarbodiimide) were obtained
commercially. For the chemical reactions and purication of the
peptides, methanol, dimethylformamide (DMF), ethyl acetate
and hexane were dried according to the reported literature
procedures. The reactions were monitored by thin-layer chro-
matography (TLC). All the intermediates and nal compounds
were puried and characterized using NMR (400 MHz) and mass
spectroscopy.
General
Mass spectrometry was performed on a Bruker MicrOTOF-Q II
by positive-mode electrospray ionization. All NMR spectra were
recorded on a Bruker AV 400 MHz spectrometer at 298 K. The PL
spectra of the lms (C ¼ 20 mmol Lꢀ1) were measured on
a Horiba ScienticFluoromax-4 spectrophotometer. The FT-IR
spectra of all the reported compounds were performed using
a Bruker (Tensor-27) FT-IR spectrophotometer. A Raman study
was performed on a Micro Raman system from Jobin Yvon
Horiba LABRAM-HR visible (400–1100 nm) equipped with an
Ar+ laser (488 nm, 10 mW) excitation source and CCD detector.
Fig.
1 (a) Typical topochemical polymerization mechanism. (b)
Schematic representation of the preparation method used for
compound 1 on a glass substrate for photochemical reaction in the
solid state for 1 h.
Synthesis of compounds
Synthesis of methyl 4-((trimethylsilyl)ethynyl)benzoate 6.
Methyl 4-iodobenzoate (9 g, 34.35 mmol), [PdCl2(PPh3)2]
(1.203 g, 1.71 mmol), CuI (0.0654 g, 0.3435 mmol) and Et3N (40
mL) were added to a two-necked round bottom ask equipped
with a condenser and magnetic stirrer and supplied with an
inert atmosphere (Scheme S1, ESI†). The mixture was purged
with Ar ow for 30 min and then trimethylsilylacetylene
(1.686 g, 17.175 mmol) was added. The reaction mixture was
nanostructures synthesized via photochemical polymerization
show high photocatalytic activity for the photodecomposition of
phenol and methyl orange under visible-light irradiation.52
Inspired by the diverse self-assembly nature of peptide
bolaamphiphiles,53–59 we demonstrate the topochemical poly-
merization of two dipeptide appended diphenylbutadiynes on
a solid surface that exhibit different morphologies.
In this regard, we have synthesized two dipeptide appended
diphenylbutadiynes-based bolaamphiphiles, HO-Phe-Leu-DPB-
Leu-Phe-OH (compound 1) and HO-Tyr-Leu-DPB-Leu-Tyr-OH
(compound 2) (DPB ¼ diphenylbutadiyne, Phe ¼ phenylala-
nine, Leu ¼ leucine, Tyr ¼ tyrosine), to examine their
morphological patterns before and aer UV irradiation (Fig. 1).
The self-organization of the dipeptide appended poly
(diphenylbutadiyne)s was controlled based on the dipeptide-
sequence and concentration of the bolaamphiphile. The
morphological alternations of the two compounds under UV
irradiation have been studied using SEM. This study corre-
sponds to a step forward in the design of porous polymer
network structures from brillar structures.60 The porous poly-
meric network structures adsorbed CO2 gas almost four times
higher than the brillar network structures of self-assembled
molecules. Thus, the rational design of light induced
diacetylene-based porous covalent organic polymers has
a prominent impact on CO2 adsorption.
ꢁ
slowly heated up to 80 C and stirred for 12 h. Aer cooling to
room temperature, the reaction mixture was ltered to remove
any insoluble materials and the solid was washed with CH2Cl2.
The ltrates were combined and concentrated under reduced
pressure to afford a yellow-orange residue, which was extracted
with CH2Cl2 (3 ꢂ 50 mL). The organic layer was washed twice
with H2O and dried over (Na2SO4), and evaporated under
vacuum to yield 6. Purication was carried out using silica gel
column chromatography (100–200 mesh) using DCM and
hexane (0.1 : 9.9) as the eluent to obtain 6 (7.5 g, 32.32 mmol,
94%) as a yellow powder. 1H-NMR (400 MHz, CDCl3): d 7.98
(d, 2H, J ¼ 8 Hz), 7.53 (d, 2H, J ¼ 8 Hz), 3.91 (s, 3H, OCH3), 0.26
(s, 9H) ppm. 13C NMR (100 MHz, CDCl3): d 166.4, 131.8, 129.6,
129.3, 127.7, 104.0, 97.6, 52.1 ppm.
Synthesis of methyl 4-ethynylbenzoate 7. Methyl 4-((trime-
thylsilyl)ethynyl)benzoate (7.48 g, 32.164 mmol) was stirred in
methanol (40 mL) and potassium carbonate (8.874 g, 64.328 mmol)
was added. The mixture was stirred for 90 min. The progress of
the reaction was monitored by thin layer chromatography
(TLC). Aer completion of the reaction, the solvent was removed
under vacuum. 1 N HCl (30 mL) was slowly added and the
Experimental section
Materials
Methyl 4-iodo benzoate, trimethylsilylacetylene (TMSA), tetra- product was extracted with dichloromethane. The collected
methylethylenediamine (TMEDA), CuCl (copper(I) chloride), CuI DCM extract was dried over Na2SO4 and concentrated under
(copper(I) iodide) and Pd(PPh3)2Cl2 (bis(triphenylphosphine) vacuum to yield 7 as a white solid. Purication was carried out
47696 | RSC Adv., 2017, 7, 47695–47703
This journal is © The Royal Society of Chemistry 2017

View Article Online
Paper
RSC Advances
using silica gel column chromatography (100–200 mesh) using
DCM and hexane (0.1 : 9.9) as the eluent to obtain 7 (2.624 g,
16.4 mmol, 51%) as a white powder. 1H-NMR (CDCl3, 400 MHz):
d 7.94 (d, 2H, J ¼ 8 Hz, aromatic H), 7.49 (d, 2H, J ¼ 8 Hz,
General procedure for methyl ester hydrolysis
Methyl ester in 10 mL of MeOH was added to a round bottom ask
and 2 N NaOH was added drop-wise (Schemes S2 and S3, ESI†).
The reaction was monitored by thin layer chromatography
(TLC). The reaction mixture was stirred overnight. 15 mL of
distilled water was added to the reaction mixture and the MeOH
was removed under vacuum. The aqueous part was washed with
diethyl ether (2 ꢂ 30 mL), then cooled in an ice-water bath for
10 min and the pH was adjusted to 2 upon the dropwise addi-
tion of 1 N HCl. It was extracted with ethyl acetate (3 ꢂ 50 mL)
and then the ethyl acetate layer was dried over anhydrous
Na2SO4 and evaporated under vacuum to yield the corre-
sponding carboxylic acid, which was used for the next step
without any further purication.
Synthesis of MeO-Leu-DPB-Leu-OMe 10. Compound 10 was
obtained as a white solid (1.2 g, 2.2 mmol, 64%). 1H-NMR (400
MHz, CDCl3): d 7.79 (d, 2H, J ¼ 8H, aromatic Hs), 7.61 (d, 2H, J ¼
8 Hz, aromatic Hs), 6.58 (d, 2H, J ¼ 8 Hz, NH of Leu), 4.86 (d, 2H,
J ¼ 8 Hz, CaHs of Leu), 3.78 (s, 6H, OCH3), 1.95 (m, 2H, CbHs of
Leu), 1.37 (m, 2H, CbHs of Leu), 1.16 (m, 2H, CgHs of Leu), 1.00
(m, 12H, CdHs of Leu) ppm. 13C NMR (100 MHz, CDCl3):
d 173.26, 166.77, 132.40, 126.87, 81.28, 75.58, 52.51, 50.90,
41.59, 33.62, 25.28, 24.68, 24.60, 22.48, 21.77 ppm. ESI-MS:
calcd for [C32H36N2O6 + Na]+ 567.2538, found 567.2455.
Synthesis of HO-Leu-DPB-Leu-OH 11. Compound 11 was
aromatic H), 3.85 (s, 3H, OCH3), 3.16 (s, acetylene H) ppm. 13
C
NMR (100 MHz, CDCl3): d 166.3, 131.9, 130.0, 129.3, 126.6, 82.7,
79.9, 52.1 ppm.
Synthesis of 1,4-bis(p-carbomethoxybenzene)-1,3-butadiyne 8.
Methyl 4-ethynylbenzoate 7 (2.5 g, 15.624 mmol) was dissolved in
acetone (40 mL). Copper(I) chloride (33.07 mg, 0.328 mmol) and
TMEDA (58.53 mg, 0.494 mmol) were added and the mixture was
stirred under open air conditions for 1 d. The precipitate was
ltered and washed with acetone (1 ꢂ 25 mL) and then washed
with chloroform (1 ꢂ 25 mL) and the solvent was removed by
rotary evaporation to give crude 8. Purication was carried out
using silica gel column chromatography (100–200 mesh) using
toluene as the eluent to obtain 8 (2.04 g, 6.41 mmol, 41.1%) as
a white solid. 1H-NMR (CDCl3, 400 MHz): d 8.01 (d, 4H, J ¼
8.4 Hz), 7.59 (d, 4H, J ¼ 8.4 Hz), 3.93 (s, 6H, CH3) ppm. 13C NMR
(CDCl3, 100 MHz) d 166.35, 132.59, 130.66, 129.69, 126.22, 81.99,
76.39, 52.49 ppm. ESI-MS: calcd for [C20H14O4 + Na]+ 341.0892,
found 341.1.
Synthesis of 4,40-(buta-1,3-diyne-1,4-diyl)dibenzoic acid 9.
1,4-Bis(p-carbomethoxybenzene)-1,3-butadiyne (1.9 g, 5.966
mmol) and NaOH (2.386 g, 59.66 mmol) were dissolved in
a mixture of THF (25 mL) and H2O (25 mL). The solution was
stirred at room temperature overnight. The pH of the solution
was then adjusted to pH 2 with 1 N HCl solution. A precipitate
was formed, which was collected by ltration, washed with H2O
and dried in air to afford 9 (1.186 g, 4.089 mmol, 69%) as a white
solid, which was used for the next step without further puri-
cation. The product exhibited low solubility in DMSO-d6 for
NMR characterization; triethylamine was added to the NMR
1
obtained as a white solid (897 mg, 1.73 mmol, 95%). H-NMR
(400 MHz, DMSO-d6): d 8.69 (d, 2H, J ¼ 8 Hz, NH of Leu), 7.88
(d, 4H, J ¼ 8 Hz, aromatic Hs), 7.68 (d, 4H, J ¼ 8 Hz, aromatic
Hs), 4.38 (m, 2H, CaHs of Leu), 1.7 (m, 4H, CbHs of Leu), 1.55
(m, 2H, CgHs of Leu), 0.87 (m, 12H, CdHs of Leu) ppm. 13C NMR
(100 MHz, DMSO-d6): d 174.36, 167.87, 134.30, 130.77, 80.18,
76.58, 53.51, 51.70, 43.39, 35.55, 26.28, 23.50, 22.60, 21.70 ppm.
ESI-MS: calcd for [C30H32N2O6 + Na]+ 539.2158, found 539.2088.
1
sample to improve the solubility of 9. H-NMR (DMSO-d6, 400
Synthesis
of
MeO-Phe-Leu-DPB-Leu-Phe-OMe
12.
MHz): d 7.96 (d, 4H, J ¼ 8 Hz), 7.6 (d, 4H, J ¼ 8.0 Hz, 4H) ppm.
13C NMR (CDCl3, 100 MHz): d 168.87, 139.65, 131.63, 129.27,
121.29, 82.19, 74.19 ppm.
Compound 12 was obtained as a white solid (393 mg,
1
0.46 mmol, 64%). H-NMR (400 MHz, CDCl3): d 8.2 (d, 1H, J ¼
8 Hz, NH of Leu), 7.73 (d, 1H, J ¼ 8 Hz, NH of Leu), 7.67 (d, 1H, J
¼ 8 Hz, NH of Phe), 7.57 (d, 1H, J ¼ 8 Hz, NH of Phe), 7.42–6.32
(m, 18 Hs of aromatic ring), 4.84 (m, 2H, CaHs of Phe), 4.45 (m,
2H, CaHs of Leu), 3.15 (m, 2H, CbHs of Phe), 3.05 (m, 2H, CbHs
of Phe), 1.7 (m, 4H, CbHs of Leu), 1.24 (m, 2H, CgHs of Leu), 0.91
(m, 12H, CdHs of Leu) ppm. 13C NMR (100 MHz, CDCl3):
d 171.47, 157.00, 129.56, 128.90, 127.46, 60.70, 53.43, 52.63,
48.47, 38.16, 34.26, 26.24, 25.24, 25.03, 23.50, 21.36, 14.50 ppm.
ESI-MS: calcd for [C50H54N4O8 + Na]+ 861.3839; found 861.3786.
Synthesis of HO-Phe-Leu-DPB-Leu-Phe-OH 1. Compound 1
was obtained as a white solid (346 mg, 0.427 mmol, 95%). FT-IR
(KBr, n, cmꢀ1): N–H 3272 (N–H, amide A), 1734 (C]O, free
carboxylic), 1649 (C]O, amide I), 1541 (N–H, amide II). 1H-
NMR (400 MHz, DMSO-d6): d 12.68 (s, 2H, COOH), 8.51 (d,
2H, J ¼ 8 Hz, NH), 8.14 (d, 2H, J ¼ 8 Hz, NH), 7.89 (d, 2H, J ¼
8 Hz, aromatic H), 7.59 (d, 2H, J ¼ 8 Hz, aromatic Hs), 7.22 (m,
10H of Phe aromatic ring), 4.57 (m, 2H, CaHs of Phe), 4.46 (m,
2H, CaHs of Leu), 3.05 (m, 2H, CbHs of Phe), 2.94 (m, 2H, CbHs
of Phe), 1.67 (m, 4H, CbHs of Leu), 1.51 (m, 2H, CgHs of Leu),
0.90 (m, 12H, CdHs of Leu) ppm. 13C NMR (100 MHz, DMSO-d6):
General procedure for peptide coupling
Compound 9 (1.0 equiv.) was dissolved in dry DMF (4 mL gꢀ1
)
and stirred on an ice-water bath (Schemes S2 and S3, ESI†). The
methyl ester protected amino acid was isolated from its corre-
sponding methyl ester hydrochloride (4.0 equiv.) by neutrali-
zation and subsequently extracted twice with ethyl acetate
(2 ꢂ 30 mL). The collected ethyl acetate extracts were dried over
anhydrous Na2SO4 and concentrated to 5 mL. The solution was
then added to the pre-cooled reaction mixture followed by the
addition of HOBt (2.0 equiv.) and dicyclohexylcarbodiimide
(DCC) (2.2 equiv.). The reaction mixture was stirred overnight.
The residue was extracted by ethyl acetate (50 mL) and the DCU
was removed by ltration. The organic layer was washed with 1 M
HCl (3 ꢂ 50 mL), brine (2 ꢂ 50 mL), 1 M sodium carbonate
(3 ꢂ 50 mL), brine (2 ꢂ 50 mL), dried over anhydrous Na2SO4 and
evaporated in vacuum. Purication was carried out using silica
gel column chromatography (100–200 mesh) using hexane–ethyl
acetate (9 : 1) as the eluent to obtain the desired product.
This journal is © The Royal Society of Chemistry 2017
RSC Adv., 2017, 7, 47695–47703 | 47697

View Article Online
RSC Advances
Paper
d 177.95, 177.19, 170.64, 142.67, 139.40, 136.75, 134.37, 133.33,
131.60, 129.71, 88.14, 88.04, 58.53, 56.84, 41.77, 29.55, 28.26,
26.66 ppm. ESI-MS: calcd for [C48H50N4O8 + Na]+ 833.3526,
found 833.3264.
DFT calculations
DFT calculations were performed using Gaussian 09 to evaluate
the role of the dipeptide side chains in the transformation of
morphology during topochemical polymerization. DFT calcu-
lations employing the B3LYP functional were carried out on
monomer and short oligomers of the conjugated organic poly-
mer. For efficient calculation, we simplied the molecular
structure using a polydiacetylene chain without the peptide side
chain. A long dipeptide side chain creates overlapping of the
orbitals leading to steric strain. To avoid such problems, we
carried out the DFT calculation of the conjugated organic
polymer without considering the peptide side chain.
Synthesis of MeO-Tyr-Leu-DPB-Leu-Tyr-OMe 13. Compound
13 was obtained as a white solid (600 mg, 0.688 mmol, 89.6%).
1H-NMR (400 MHz, DMSO-d6): d 9.26 (s, 2H, phenolic OH of
Tyr), 8.50 (d, 2H, J ¼ 8 Hz, NH), 8.25 (d, 2H, J ¼ 8 Hz, NH), 7.87
(d, 2H, J ¼ 8 Hz, aromatic H), 7.57 (d, 2H, J ¼ 8 Hz, aromatic H),
6.98 (d, 4H, J ¼ 8 Hz, 4H of Tyr aromatic ring), 6.61 (d, 4H, J ¼
8 Hz, 4H of Tyr aromatic ring), 4.38 (d, 2H, J ¼ 8 Hz, CaHs of
Leu), 3.55 (s, 6H of COOCH3), 3.05 (m, 2H, CbHs of Phe), 2.88
(m, 2H, CbH of Tyr), 1.62 (m, 4H, CbHs of Leu), 1.25 (m, 2H,
CgHs of Leu), 0.89 (m, 12H, CdHs of Leu) ppm. 13C NMR (100
MHz, DMSO-d6): d 199.15, 192.93, 184.26, 140.56, 137.87,
134.37, 133.33, 130.30, 128.66, 115.97, 115.50, 94.92, 91.84,
41.17, 33.94, 24.92, 22.79, 131.60, 129.71, 88.14, 88.04, 58.53,
56.84, 41.77, 29.55, 28.26, 26.66 ppm. ESI-MS: calcd for
[C50H54N4O10 + Na]+ 893.3840, found 893.3960.
Thermogravimetric analysis (TGA)
Thermogravimetric analysis (TGA) was performed using
a METTLER TOLEDO TGA instrument. The samples were
heated from 25 to 600 ꢁC at a constant rate of 5 ꢁC minꢀ1 under
a nitrogen atmosphere.
Synthesis of HO-Tyr-Leu-DPB-Leu-Tyr-OH 2. Compound 2
was obtained as a white solid (456 mg, 0.541 mmol, 95%). FT-IR
(KBr, n, cmꢀ1): 3284 (N–H, amide A), 1761 (C]O, free carbox-
ylic), 1621 (C]O, amide I), 1536 (N–H, amide II). 1H-NMR (400
MHz, DMSO-d6): d 12.62 (m, 2H, COOH), 9.18 (s, 2H, phenolic-
OH of Tyr), 8.52 (d, 2H, J ¼ 8 Hz, NH of Tyr), 8.03 (d, 2H, J ¼
8 Hz, NH), 7.88 (d, 2H, J ¼ 8 Hz, aromatic Hs), 7.58 (d, J ¼ 8 Hz,
2H, aromatic Hs), 7.00 (d, 4H, J ¼ 8 Hz, 4H of Tyr aromatic ring),
6.61 (d, 4H, J ¼ 8 Hz, 4H of Phe aromatic ring), 4.55 (d, 2H, J ¼
8 Hz, CaHs of Tyr), 4.38 (d, 2H, J ¼ 8 Hz, CaHs of Leu), 2.94 (m,
2H, CbHs of Tyr), 2.91 (m, 2H, CbHs of Tyr), 1.52 (m, 4H, CbHs of
Leu), 1.25 (m, 2H, CgHs of Leu), 0.90 (m, 12H, CdHs of
Leu) ppm. 13C NMR (100 MHz, DMSO-d6): d 178.06, 177.12,
170.70, 161.12, 139.43, 136.76, 135.29, 133.03, 132.61, 129.70,
120.15, 88.15, 88.06, 58.88, 56.84, 41.04, 29.57, 26.27,
26.64 ppm. ESI-MS: calcd for [C48H50N4O10 + Na]+ 865.3425,
found 865.3583.
Gas sorption measurement
Gas (N2/CO2) adsorption/desorption experiments were carried
out using a Quantachrome Autosorb IQ2 Automated Gas Sorp-
tion System at 77 K (N2 sorption experiments) and 298 K (CO2
sorption experiments) over the pressure range between 0.025
bar and 1 bar (40 points system). Before the sorption
measurements, monomer 1, polymer 1, monomer 2 and poly-
mer 2 were degassed for 10 h with a heating rate of 5 ꢁC minꢀ1
.
From the gas adsorption results at low P/P0, the pore size
distribution of the samples was calculated using the BJH (Bar-
rett–Joyner–Halenda analysis) method. The BET surface area
was calculated from the Brunauer–Emmett–Teller (BET)
equation.
Results and discussion
Topochemical polymerization on solid surface
Dipeptide appended diphenylbutadiyne-based bolaamphi-
philes (compounds 1 and 2, C ¼ 20 mmol Lꢀ1) were suspended
in methanol for dissolution (Fig. 1). Compound 1 in methanol
and a two-day aged methanol solution of compound 2 were then
drop-casted on quartz glass to prepare their lms. Compounds
1 and 2 based lms were allowed to polymerize under UV light
irradiation (72 W, 254 nm). A lm based on compound 1 turned
blue whereas the lm based on compound 2 turned yellow aer
60 min of UV irradiation. As a result of an effective regioselective
1,4-polymerization of the self-organized compound 1, blue
colour was observed. UV-Vis spectra were collected to under-
stand the variation in the absorption spectra of the bolaam-
phiphiles on solid surfaces aer the topochemical
polymerization reaction (Fig. 2). Prior to UV irradiation,
compound 1 absorbed at 340 nm. A new peak appeared in the
Sample preparation
Compound solutions were prepared by mixing 16.2 mg of
compound 1 and 16.8 mg of compound 2, individually in 1 mL
of methanol in glass vials. The compounds were completely
dissolved by shaking. Then, 1 mL of each of the as-prepared
solutions was drop-casted on clean and dried glass slides and
was allowed to dry in air at room temperature. Then, the lms
were irradiated using 254 nm UV light. SEM measurements
were performed on the dried lms aer 60 min of UV irradiation
by coating with gold for both compounds 1 and 2. Field emis-
sion scanning electron microscopic study was performed on
a Carl Zeiss microscope (model-Supra 55).
Topochemical polymerization procedure
Topochemical polymerization was accompanied on the lms visible-light region at 610 nm (Fig. 2a) aer polymerization. The
upon irradiation at 254 nm using a 72 W UV lamp at 25 ꢁC. For new peak at 610 nm appeared due to the formation of poly-
these experiments, the dried thin lms of the compounds were diacetylene (the lm turned to blue aer 60 min of UV irradi-
irradiated for 1 h. A condenser was attached to the reactor to ation for compound 1).61,62 Similarly, the UV-Vis spectra of
ꢁ
maintain its temperature at about 25 C.
compound 2 were recorded (Fig. 2b) before and aer UV
47698 | RSC Adv., 2017, 7, 47695–47703
This journal is © The Royal Society of Chemistry 2017

View Article Online
Paper
RSC Advances
3100–3500 cmꢀ1 were observed aer the topochemical poly-
merization reaction, which are indicative of the formation of
weakly hydrogen bonded NH groups. However, a sharp peak at
2110 cmꢀ1 appeared due to the presence of C^C in compound
1. The intensity of the corresponding C^C peak decreases aer
UV irradiation. Aer topochemical polymerization, the amide I
band at 1650 cmꢀ1 was shied to 1627 cmꢀ1. The FT-IR results
evidently support the structural changes during the polymeri-
zation reaction occurring aer UV irradiation.65,66 The FT-IR
spectra were also acquired for compound 2 before and aer
the topochemical polymerization reaction. Fig. 2f shows the FT-
IR spectra for compound 2. The FT-IR peaks at 3284 cmꢀ1 for
amide N–H stretching, 1665 cmꢀ1 and 1633 cmꢀ1 for amide I
and 1536 cmꢀ1 for amide II are observed prior to the photo-
chemical polymerization reaction of compound 2. Low intense
peaks in the region of 3100–3500 cmꢀ1 were observed aer the
topochemical polymerization, which are indicative of the
formation of weakly hydrogen-bonded NH groups. These results
suggest that intermolecular hydrogen bonding between the
N–H and C]O of the amide groups drives the formation of the
self-assembled ber architecture prior to UV polymerization.
The self-organized structures were formed due to the polymer-
ization of compounds 1 and 2 induced by UV irradiation.
The change in morphology of the two compounds under UV
polymerization was studied using scanning electron micros-
copy (SEM) (Fig. 3). Compound 1, aer dissolution in methanol,
was drop-casted onto quartz glass slides and revealed bers
Fig. 2 UV-Vis spectra of (a) compound 1 and (b) compound 2 before
and after UV polymerization. Raman spectra of (c) compound 1 and (d)
compound 2 before and after 60 min of topochemical polymerization.
FTIR spectra of (e) compound 1 and (f) compound 2 before (red line)
and after 60 min (black line) of topochemical polymerization.
irradiation. Compound 2 absorbed a peak at 334 nm prior to UV (Fig. 3a). Aer 60 min of UV irradiation, the morphology alters
irradiation, which was attributed to the p–p* transition of to a porous network structure (Fig. 3b). The entire experiment
diphenylbutadiyne. Aer 60 min of UV irradiation, a new broad was performed with a 20 mmol Lꢀ1 solution of compound 1.
peak appeared at 658 nm and the lm turned to yellow.
The experiments were performed in triplicate and similar
Fourier-transform Raman spectroscopy (FT-Raman) and FT- results were obtained. Similar experiments were performed with
IR spectroscopy were used to monitor the polymerization reac- 15 mmol Lꢀ1 and 30 mmol Lꢀ1 solutions of compound 1.
tion of compounds 1 and 2 on the solid surface (Fig. 2). Before Different types of morphological changes were observed with
UV irradiation, the Raman spectrum of compound 1 shows respect to the duration of UV irradiation for 15 mmol Lꢀ1 and
a peak at 2111 cmꢀ1, which is assigned to the regular stretching 30 mmol Lꢀ1 solutions of compound 1 (Fig. S1 and S2, ESI†).
mode of 1,3-butadiyne. Aer UV irradiation, the characteristic Here, the self-organized structures of compound 1 change into
peak at 2111 cmꢀ1 disappears and a new peak appears at polymerized porous network structures upon topochemical
2106 cmꢀ1 aer 60 min of the polymerization reaction. The polymerization with different morphological features. The top-
peak at 2106 cmꢀ1 arises due to the presence of a C^C bond ochemical polymerization of compound 2 was also performed on
within the conjugated polymer aer UV irradiation. A new peak the solid surface and in the solid state (Fig. S3, ESI†). Compound
at 1565 cmꢀ1 appears aer UV irradiation due to the formation 2 (20 mmol Lꢀ1) was dissolved in methanol. Instant deposition of
of C]C bonds. It has been reported that the characteristic the methanolic solution of compound 2 did not form a self-
peaks between 1400 and 1600 cmꢀ1 appear due to the stretching assembled structure. However, the two-day aged solution of
vibration of enyne (Fig. 2c).63 Compound 2 shows a character- compound 2 forms brillar morphology (Fig. S3a, ESI†).
istic peak at 2114 cmꢀ1, which is attributed to the presence of
the C^C stretching vibration. However, the C^C stretching
vibration peak shied to 2109 cmꢀ1 aer 1 h of UV irradiation. A
new peak appears at 1607 cmꢀ1 aer UV irradiation of
compound 2 due to the formation of C]C bonds (Fig. 2d).63,64
These results indicate that both compounds were transformed
into poly(diphenylbutadiyne) upon UV irradiation. Fig. 2e and f
show the FT-IR spectra of compounds 1 and 2 prior and aer
the UV polymerization reaction. As shown in Fig. 2e, the
characteristic peaks at 3317 and 3271 cmꢀ1 for amide N–H
Fig. 3 SEM images at different times of the UV reaction of compound
1: (a) before the UV reaction and (b) after 60 min of UV irradiation
stretching, 1650 cmꢀ1 for amide I and 1537 cmꢀ1 for
amide II band were observed. Weak peaks in the region of (polymer 1).
This journal is © The Royal Society of Chemistry 2017
RSC Adv., 2017, 7, 47695–47703 | 47699

View Article Online
RSC Advances
Paper
The brillar morphology obtained for the two compounds 1 and distance between the two molecules due to the formation of the
˚
2 are relatively different. This differential morphology was diyne was 3.6 A. This result supports the crystal structure of
observed probably due to the presence of the polar phenolic –OH a reported diyne system.71 The distance between the two peptide
group present in the tyrosine containing compound 2. Due to the molecules should be 4.7 A.72 Hence, the hydrogen bonds between
˚
presence of the phenolic –OH group, compound 2 exhibits the amide groups in the peptide molecules are disrupted. As
a more hydrophilic nature when compared with the hydrophobic a result, the brillar structures transform to porous network
phenylalanine-based compound 1. The different lattice packing structures.
features also drive the discrepancy of the typical brous
Thermogravimetric analysis (TGA) was performed to analyse
morphological properties in a particular solvent.67 Aer 60 min the thermal stability of compound 1, polymer 1, compound 2
of UV irradiation, compound 2 shows a porous network structure and polymer 2 (Fig. S4, ESI†). The decomposition temperature
ꢁ
(Fig. S3b, ESI†). Here, UV polymerization changes the of compounds 1 and 2 was observed between 150–200 C with
morphology and self-organization of compound
1 and an initial weight loss of 2–6%. However, the decomposition
compound 2 on a solid surface.68 For both the compounds, the temperature of polymers 1 and 2 was observed between
hydrogen bonding and p–p interactions between the molecules 500–600 ꢁC with an initial weight loss of 2–6%. Hence, the
are involved in the formation of the self-assembled bers. The thermal stability of the polymers was higher than their corre-
dipeptide appended diphenylbutadiyne-based molecules are sponding monomeric compounds.
linear due to the presence of the two conjugated triple bonds.
In current research, porous covalent organic polymers with
Due to an increase in degree of polymerization, the polymers high surface areas have gained particular interest in the area of
become aggregated and the morphology changes aer 1 h of UV greenhouse gas storage.73 To analyse their porous features, gas
irradiation (Scheme 1). Aer UV irradiation, the hydrogen bonds adsorption studies were executed with the dried self-assembled
involved in the dipeptides become weaker. Aer 60 min of UV structures of compounds 1 and 2 grown from a methanol
irradiation, the bers are re-organized to form a porous network solution and the 60 min UV irradiated polymers of 1 and 2.
structure. This was evidenced in the FT-IR spectra with the peak Polymer 1 exhibits 24.22 times more N2 gas uptake than
intensity of the NH stretching of the amide bonds between 3000– compound 1 (Table 1). The BET (Brunauer–Emmett–Teller)
3300 cmꢀ1 decreasing aer 1 h of UV irradiation. At this time, the surface area of compound 1 was calculated to be 4.905 m2 gꢀ1
formation of polydiacetylene was also evidenced by Raman whereas the BET surface area becomes 106.38 m2 gꢀ1 for
spectroscopy as new peaks corresponding to the formation of polymer 1. Thus, the surface area of polymer 1 exhibits
enyne developed between 1400–1600 cmꢀ1
.
Intermolecular a 21.68 fold higher surface area than compound 1. The pore
69,70
hydrogen bonding becomes weaker and the formation of poly- volume of compound 1 was calculated to be 0.0144 cm3 gꢀ1
,
meric enyne is responsible for the structural changes observed whereas the pore volume of polymer 1 was revealed to be
for compound 1. Similarly, compound 2 shows the brillar 0.3845 cm3 gꢀ1 (Fig. 4). The BET surface area of compound 2
morphology prior to UV irradiation due to the linear congura- was measured to be 10.599 m2 gꢀ1, whereas the BET surface
tion in the presence of the two conjugated triple bonds. Aer 1 h area becomes 58.800 m2 gꢀ1 for polymer 2. Thus, the surface
of UV irradiation, the hydrogen bonds become weaker as evi- area of polymer 2 was 5.54 times higher than the surface area of
denced by the FTIR spectra. The brillar structures turn into compound 2. The pore volume of compound 2 was measured to
polymerized porous networks with an alternating ene-yne be 0.0156 cm3 gꢀ1 whereas the pore volume of polymer 2 was
conguration. From the DFT study, we have observed that aer 0.1966 cm3 gꢀ1. Interestingly, the porous polymer structures
the topochemical polymerization reaction, steric crowding show enhanced sorption preferences than their corresponding
between peptide side chains disrupts the hydrogen bonding. Due monomers.74–77 The porosity developed on the surface aer light
to disruption of the hydrogen bonding, the brillar morphology induced polymerization of compounds 1 and 2 was in good
transforms to a porous network morphology. The closest agreement with the SEM images. According to the IUPAC
Scheme 1 Possible self-assembly mechanism of the dipeptide appended diphenylbutadiyne based compound 1.
47700 | RSC Adv., 2017, 7, 47695–47703
This journal is © The Royal Society of Chemistry 2017

View Article Online
Paper
RSC Advances
Table 1 BET surface properties and pore parameters of compound 1, polymer 1, compound 2 and polymer 2 obtained from the N2 and CO2
sorption studies
Surface area
(m2 gꢀ1
Pore volume
Pore size
(diameter in nm)
Maximum amount
Parameter
)
(cm3 gꢀ1
)
Isotherm type
of gas adsorbed (cm3 gꢀ1
)
N2 sorption
Compound 1
Polymer 1
Compound 2
Polymer 2
4.905
106.368
10.599
58.800
0.0144
0.3845
0.0156
0.1966
1.744
2.7196
2.158
I
I
I
I
9.38
227.22
10.34
2.7127
128.28
CO2 sorption
Compound 1
Polymer 1
Compound 2
Polymer 2
—
—
—
—
0.01427
0.05944
0.0141
0.7378
0.8734
0.8066
1.0477
6.8
29.71
6.73
0.05891
28.08
nomenclature, the N2 gas isotherms measured for compounds solids such as TCMP-3 and TCMP-0 adsorb 1.29 mmol gꢀ1 and
1 and 2, and polymers 1 and 2 can be classied by type I 1.34 mmol gꢀ1 CO2, respectively. Other COPs such as CMP-1
isotherms corresponding to a hierarchically porous material. As (1.18 mmol gꢀ1), CMP-1-(COOH) (0.95 mmol gꢀ1), CMP-1-
shown in Fig. 4c, the CO2 uptake of compound 1 was measured (NH2) (0.95 mmol gꢀ1), CMP-1(CH3)2 (0.94 mmol gꢀ1), CMP-1-
to be 6.8 cm3 gꢀ1. However, the CO2 uptake was calculated to be (OH) (1.07 mmol gꢀ1), CMP-5 (1.1 mmol gꢀ1), CMP-5
29.71 cm3 gꢀ1 for polymer 1. Thus, polymer 1 exhibits 4.36 times (0.63 mmol gꢀ1), PMF-1 (1.33 mmol gꢀ1
) and TCMP-5
more CO2 storage capacity than compound 1. The CO2 uptake of (0.681 mmol gꢀ1) also adsorb CO2.78–82 In addition, the advan-
compound 2 was measured to be 6.73 cm3 gꢀ1. However, the tage of our as-prepared polymer-adsorbents is that they can be
CO2 uptake observed for polymer 2 was measured to be synthesized easily via a light-assisted polymerization reaction.
28.08 cm3 gꢀ1 (Fig. 4d). Thus, polymer 2 shows 4.17 times more Captivatingly, these polydiacetylene-adsorbents can capture
CO2 storage capacity than compound 2 (Table 1). The CO2 CO2 gas in a signicant amount. The development of the porous
uptake capacities of the synthesized covalent organic polymers architectures with enhanced surface areas aer topochemical
(1.32 mmol gꢀ1 for polymer 1 and 1.25 mmol gꢀ1 for polymer 2) polymerization was responsible for their enhanced CO2
at 1 bar are comparable to the previously reported adsorption sorption.
capacities of COPs and porous organic solids. Porous organic
Conclusion
In summary, porous covalent organic polymers were developed
using the topochemical polymerization of dipeptide appended
diphenylbutadiyne-based bolaamphiphiles on a solid surface.
Topochemical polymerization leads to change in the self-
organized morphological features from bers to porous
network structures. The surface area, pore volume and porosity
of the polymers were increased several times when compared to
their corresponding compounds prior to polymerization. Poly-
mers 1 and 2 exhibit 4.2 and 4.1 times more CO2 sorption
behaviour than compounds 1 and 2, respectively. The porous
polymer networks could interact with the N2 and CO2 gases
through their amide bonds and the close proximity of the
molecules through the covalent enyne bonds. The polymers are
thermally stable when compared to their monomers, which was
revealed by our TGA experiments. The light induced develop-
Fig. 4 (a) N2 adsorption and desorption isotherms at 77 K (P0 ¼ 1 atm)
obtained for compound 1 and polymer 1. (b) N2 adsorption and
desorption isotherms at 77 K (P0 ¼ 1 atm) obtained for compound 2
and polymer 2. (c) CO2 adsorption and desorption isotherms at 298 K
(P0 ¼ 1 atm). (d) CO2 adsorption and desorption isotherms at 298 K
(P0 ¼ 1 atm) obtained for compound 2 and polymer 2.
ment of covalent organic polymers presented in this study
unbolts new possibilities for tuning the porous properties of
organic polymers for a variety of applications, including the
design of catalysts and promising adsorbents for industrial
applications.
This journal is © The Royal Society of Chemistry 2017
RSC Adv., 2017, 7, 47695–47703 | 47701

View Article Online
RSC Advances
Paper
18 S. Wan, J. Guo, J. Kim, H. Ihee and D. Jiang, Angew. Chem.,
Int. Ed., 2009, 48, 3207.
Conflicts of interest
˜
19 C. R. DeBlase, K. E. Silberstein, T.-T. Truong, H. D. Abruna
There are no conicts to declare.
and W. R. Dichtel, J. Am. Chem. Soc., 2013, 135, 16821–16824.
20 J. Hotz and W. Meier, Langmuir, 1998, 14, 1031–1036.
21 S. Lei, X. Gao, D. Cheng, L. Fei, W. Lu, J. Zhou, Y. Xiao,
B. Cheng, Y. Wang and H. Huang, Eur. J. Inorg. Chem.,
2017, 2017, 1892–1899.
22 A. Perino, M. Schmutz, S. Meunier, P. J. Mesini and
A. Wagner, Langmuir, 2011, 27, 12149–12155.
23 N. Laggoune, F. Delattre, J. Lyskawa, F. Stoffelbach,
J. M. Guigner, S. Ruellan, G. Cooke and P. Woisel, Polym.
Chem., 2015, 6, 7389–7394.
Acknowledgements
AKD sincerely acknowledges NanoMission, Department of
Science & Technology (Project No. SR/NM/NS-1458/2014), New
Delhi, India for nancial support. SB is thankful to MHRD, New
Delhi for his doctoral fellowship and MK is thankful to IIT
Indore for his postdoctoral research fellowship. The sophisti-
cated instrumentation centre (SIC), IIT Indore is acknowledged
for providing access to their instrumentation. The authors
thank the UGC-DAE Consortium for Scientic Research, Indore
for their help in recording the Raman data.
24 V. V. Atuchin, T. A. Gavrilova, V. G. Kostrovsky,
L. D. Pokrovsky and I. B. Troitskaia, Inorg. Mater., 2008, 44,
622.
25 A. D. Merg, J. C. Boatz, A. Mandal, G. Zhao, S. Mokashi-
Punekar, C. Liu, X. Wang, P. Zhang, P. C. A. van der Wel
and N. L. Rosi, J. Am. Chem. Soc., 2016, 138, 13655–13663.
References
1 R. Babarao and J. Jiang, Energy Environ. Sci., 2008, 1, 139– 26 L. Ziserman, H.-Y. Lee, S. R. Raghavan, A. Mor and
143. D. Danino, J. Am. Chem. Soc., 2011, 133, 2511–2517.
2 Z. Xiang, R. Mercado, J. M. Huck, H. Wang, Z. Guo, W. Wang, 27 F. J. M. Hoeben, P. Jonkheijm, E. W. Meijer and
D. Cao, M. Haranczyk and B. Smit, J. Am. Chem. Soc., 2015,
137, 13301–13307.
3 S. De, J. Zhang, R. Luque and N. Yan, Energy Environ. Sci.,
2016, 9, 3314–3347.
4 L. Zhai, N. Huang, H. Xu, Q. Chen and D. Jiang, Chem.
Commun., 2017, 53, 4242–4245.
A. P. H. J. Schenning, Chem. Rev., 2005, 105, 1491–1546.
28 H. Choi, M. T. Jeena, L. Palanikumar, Y. Jeong, S. Park, E. Lee
and J.-H. Ryu, Chem. Commun., 2016, 52, 5637–5640.
29 D. Mumcuoglu, M. Sardan Ekiz, G. Gunay, T. Tekinay,
A. B. Tekinay and M. O. Guler, ACS Appl. Mater. Interfaces,
2016, 8, 11280–11287.
5 Z. Xiang and D. Cao, J. Mater. Chem. A, 2013, 1, 2691–2718.
6 Y.-L. Wong, J. M. Tobin, Z. Xu and F. Vilela, J. Mater. Chem. A,
2016, 4, 18677–18686.
7 K. Park, K. Lee, H. Kim, V. Ganesan, K. Cho, S. K. Jeong and
S. Yoon, J. Mater. Chem. A, 2017, 5, 8576–8582.
8 G. Mukherjee, J. Thote, H. B. Aiyappa, S. Kandambeth,
30 P. K. Sukul, P. Bose, T. Takei, O. M. Yaghi, Y. He, M. Lee and
K. Tashiro, Chem. Commun., 2016, 52, 1579–1581.
31 X. Du, J. Zhou, J. Shi and B. Xu, Chem. Rev., 2015, 115, 13165–
13307.
32 C. Guo, Z. A. Arnon, R. Qi, Q. Zhang, L. Adler-Abramovich,
E. Gazit and G. Wei, ACS Nano, 2016, 10, 8316–8324.
S. Banerjee, K. Vanka and R. Banerjee, Chem. Commun., 33 X. Yan, P. Zhu and J. Li, Chem. Soc. Rev., 2010, 39, 1877–1890.
´
2017, 53, 4461–4464.
34 N. Baccile, A.-S. Cuvier, S. Prevost, C. V. Stevens, E. Delbeke,
9 X. Shi, Y. Yao, Y. Xu, K. Liu, G. Zhu, L. Chi and G. Lu, ACS
Appl. Mater. Interfaces, 2017, 9, 7481–7488.
J. Berton, W. Soetaert, I. N. A. Van Bogaert and S. Roelants,
Langmuir, 2016, 32, 10881–10894.
10 Z. Xiang, X. Zhou, C. Zhou, S. Zhong, X. He, C. Qin and 35 E. Yashima, N. Ousaka, D. Taura, K. Shimomura, T. Ikai and
D. Cao, J. Mater. Chem., 2012, 22, 22663–22669. K. Maeda, Chem. Rev., 2016, 116, 13752–13990.
11 G. Das, T. Prakasam, S. Nuryyeva, D. S. Han, A. Abdel-Wahab, 36 D. Jiao, J. Geng, X. J. Loh, D. Das, T.-C. Lee and
J.-C. Olsen, K. Polychronopoulou, C. Platas-Iglesias,
O. A. Scherman, Angew. Chem., Int. Ed., 2012, 51, 9633–9637.
F. Ravaux, M. Jouiad and A. Trabolsi, J. Mater. Chem. A, 37 T. Shimizu, N. Kameta, W. Ding and M. Masuda, Langmuir,
2016, 4, 15361–15369.
2016, 32, 12242–12264.
12 P. Ghosh, S. K. Saha, A. Roychowdhury and P. Banerjee, Eur. 38 J. B. Matson, Y. Navon, R. Bitton and S. I. Stupp, ACS Macro
J. Inorg. Chem., 2015, 2015, 2851–2857. Lett., 2015, 4, 43–47.
13 P. Bhanja, K. Bhunia, S. K. Das, D. Pradhan, R. Kimura, 39 M. Liu, L. Zhang and T. Wang, Chem. Rev., 2015, 115, 7304–
Y. Hijikata, S. Irle and A. Bhaumik, ChemSusChem, 2017,
10, 921–929.
14 H. Ma, H. Ren, S. Meng, Z. Yan, H. Zhao, F. Sun and G. Zhu,
Chem. Commun., 2013, 49, 9773–9775.
15 Z. Xiang, D. Cao, W. Wang, W. Yang, B. Han and J. Lu, J. Phys.
Chem. C, 2012, 116, 5974–5980.
7397.
40 C. G. Palivan, R. Goers, A. Najer, X. Zhang, A. Car and
W. Meier, Chem. Soc. Rev., 2016, 45, 377–411.
41 K. Ma, R. Xing, T. Jiao, G. Shen, C. Chen, J. Li and X. Yan, ACS
Appl. Mater. Interfaces, 2016, 8, 30759–30767.
´
42 C. E. Morgan, A. W. Dombrowski, C. M. Rubert Perez,
16 J. Sun and X. Bao, Chem.–Eur. J., 2008, 14, 7478–7488.
17 Q. Fang, J. Wang, S. Gu, R. B. Kaspar, Z. Zhuang, J. Zheng,
H. Guo, S. Qiu and Y. Yan, J. Am. Chem. Soc., 2015, 137,
8352–8355.
E. S. M. Bahnson, N. D. Tsihlis, W. Jiang, Q. Jiang,
J. M. Vercammen, V. S. Prakash, T. A. Pritts, S. I. Stupp
and M. R. Kibbe, ACS Nano, 2016, 10, 899–909.
47702 | RSC Adv., 2017, 7, 47695–47703
This journal is © The Royal Society of Chemistry 2017

View Article Online
Paper
RSC Advances
˚
43 A. C. Eldredge, M. E. Johnson, N. J. Oldenhuis and Z. Guan, 63 L. Zhu, H. Tran, F. L. Beyer, S. D. Walck, X. Li, H. Agren,
Biomacromolecules, 2016, 17, 3138–3144.
44 S. Datta and S. Bhattacharya, Chem. Soc. Rev., 2015, 44, 5596–
5637.
K. L. Killops and L. M. Campos, J. Am. Chem. Soc., 2014,
136, 13381–13387.
´
64 J. R. Neabo, K. I. S. Tohoundjona and J.-F. Morin, Org. Lett.,
45 M. Konda, B. Kauffmann, D. B. Rasale and A. K. Das, Org.
Biomol. Chem., 2016, 14, 4089–4102.
46 E. R. da Silva, M. N. M. Walter, M. Reza, V. Castelletto,
2011, 13, 1358–1361.
65 A. Potisatityuenyong, R. Rojanathanes, G. Tumcharern and
M. Sukwattanasinitt, Langmuir, 2008, 24, 4461–4463.
J. Ruokolainen, C. J. Connon, W. A. Alves and 66 E. Jahnke, J. Weiss, S. Neuhaus, T. N. Hoheisel and
I. W. Hamley, Biomacromolecules, 2015, 16, 3180–3190. H. Frauenrath, Chem.–Eur. J., 2009, 15, 388–404.
47 J. Jaworski, K. Yokoyama, C. Zueger, W.-J. Chung, S.-W. Lee 67 S. Biswas, D. B. Rasale and A. K. Das, RSC Adv., 2016, 6,
and A. Majumdar, Langmuir, 2011, 27, 3180–3187. 54793–54800.
48 J. J. Bang, K. K. Rupp, S. R. Russell, S. W. Choong and 68 M. Shirakawa, N. Fujita and S. Shinkai, J. Am. Chem. Soc.,
S. A. Claridge, J. Am. Chem. Soc., 2016, 138, 4448–4457. 2005, 127, 4164–4165.
49 S. Wang and K. S. Schanze, ACS Appl. Mater. Interfaces, 2013, 69 K. Lv, L. Zhang and M. Liu, Langmuir, 2014, 30, 9295–9302.
5, 4487.
70 J.-M. Kim, Y. B. Lee, S. K. Chae and D. J. Ahn, Adv. Funct.
Mater., 2006, 16, 2103–2109.
50 B. E. I. Ramakers, S. A. Bode, A. R. Killaars, J. C. M. van Hest
¨
and D. W. P. M. Lowik, J. Mater. Chem. B, 2015, 3, 2954–2961. 71 J.-M. Heo, Y. Kim, S. Han, J. F. Joung, S. Lee, S. Han, J. Noh,
51 K. Maeda, L. Hong, T. Nishihara, Y. Nakanishi, Y. Miyauchi,
R. Kitaura, N. Ousaka, E. Yashima, H. Ito and K. Itami, J. Am.
Chem. Soc., 2016, 138, 11001–11008.
52 M. Suzuki, J. F. K. Kotyk, S. I. Khan and Y. Rubin, J. Am.
Chem. Soc., 2016, 138, 5939–5956.
J. Kim, S. Park, H. Lee, Y. M. Choi, Y.-S. Jung and J.-M. Kim,
Macromolecules, 2017, 50, 900–913.
72 K. Morrisa and L. Serpel, Chem. Soc. Rev., 2010, 39, 3445–
3453.
73 J. Li, D. Jia, Z. Guo, Y. Liu, Y. Lyu, Y. Zhou and J. Wang, Green
Chem., 2017, 19, 2675–2686.
´
53 S. Ghosh, N. A. Kouame, L. Ramos, S. Remita, A. Dazzi,
A. Deniset-Besseau, P. Beaunier, F. Goubard, P.-H. Aubert 74 L. Wang, C. Pan, A. Liang, X. Zhou, W. Zhou, T. Wan and
and H. Remita, Nat. Mater., 2015, 14, 505–511. L. Wang, Polym. Chem., 2017, 8, 4644–4650.
54 S. R. Diegelmann, N. Hartman, N. Markovic and J. D. Tovar, 75 K. Zhang, A. Nalaparaju and J. Jiang, J. Mater. Chem. A, 2015,
J. Am. Chem. Soc., 2012, 134, 2028–2031. 3, 16327–16336.
55 C. Tomasini and N. Castellucci, Chem. Soc. Rev., 2013, 42, 76 J. Hotz and W. Meier, Langmuir, 1998, 14, 1031–1036.
156–172.
77 S.-L. Zhong, R. Xu, L.-F. Zhang, W.-G. Qu, G.-Q. Gao, X.-L. Wu
and A.-W. Xu, J. Mater. Chem., 2011, 21, 16574–16580.
78 S. Ren, R. Dawson, A. Laybourn, J. Jiang, Y. Khimyak,
D. J. Adams and A. I. Cooper, Polym. Chem., 2012, 3, 928–934.
79 S. K. Gupta, D. Kaleeswaran, S. Nandi, R. Vaidhyanathan and
R. Murugavel, ACS Omega, 2017, 2, 3572–3582.
80 Y. Zeng, R. Zou and Y. Zhao, Adv. Mater., 2016, 28, 2855–
2873.
56 I. Maity, D. B. Rasale and A. K. Das, So Matter, 2012, 8,
5301–5308.
57 I. Maity, H. S. Parmar, D. B. Rasale and A. K. Das, J. Mater.
Chem. B, 2014, 2, 5272–5279.
58 A. K. Das, I. Maity, H. S. Parmar, T. O. McDonald and
M. Konda, Biomacromolecules, 2015, 16, 1157–1168.
59 J. Kwak and S.-Y. Lee, ACS Appl. Mater. Interfaces, 2014, 6,
6461–6468.
81 A. Bhunia, V. Vasylyeva and C. Janiak, Chem. Commun., 2013,
49, 3961–3963.
60 I. W. Hamley, Angew. Chem., Int. Ed., 2014, 53, 6866–6881.
61 Q. Liu, S. Chen, J. Chen and J. Du, Macromolecules, 2015, 48, 82 Q. Xiao, J. Wen, Y. Guo, J. Hu, J. Wang, F. Zhang, G. Tu,
739–749.
Y. Zhong and W. Zhu, Ind. Eng. Chem. Res., 2016, 55,
12667–12674.
62 G. W. Coates, A. R. Dunn, L. M. Henling, D. A. Dougherty and
R. H. Grubbs, Angew. Chem., Int. Ed. Engl., 1997, 36, 248–251.
This journal is © The Royal Society of Chemistry 2017
RSC Adv., 2017, 7, 47695–47703 | 47703