Gfp chromophore integrated conjugated microporous polymers: Topological and ESPT effects on emission properties

Article abstract of DOI:10.1039/c9cc00357f

A metal free topological approach is demonstrated to mimic the photophysical properties of natural gfp by synthesizing two gfp chromophore integrated conjugated microporous polymers (o-HBDI-TEB-CMP and o-MBDI-TEB-CMP). Interestingly, owing to the structur

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Marilyn M. Olmstead, Alan L. Balch, Josep M. Poblet, Luis Echegoyenet al.
Reactivity differences of Sc
first methanofullerene derivatives of Sc
3
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=
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DOI: 10.1039/C9CC00357F
Gfp chromophore integrated conjugated microporous
polymers: Topological and ESPT effect on emission
properties
Received 00th January 20xx,
Accepted 00th January 20xx
DOI: 10.1039/x0xx00000x
Ashish Singh, Debabrata Samanta, Mrinal Boro and Tapas Kumar Maji*
www.rsc.org/
A metal free topological approach is demonstrated to mimic the properties in an artificial scaffold still remains a great
photophysical properties of the natural gfp by synthesizing the gfp challenge. Such bio-inspired emissive materials can be applied
chromophore integrated two conjugated microporous polymers as fluorescent marker in cell biology and also a chemical or
(
o-HBDI-TEB-CMP and o-MBDI-TEB-CMP). Interestingly, owing to biological fluorescent sensor. The structural rigidity is crucial
6
the structural rigidity, emission (λem = 515 nm) and excited state factor for spectroscopic signature of the chromophore. Thus,
lifetime (4.3 ns) of hydroxy substituted o-HBDI-TEB-CMP is found the gfp chomophore connecting with the organic spacer to
to be similar to the natural gfp. The crucial role of –OH group for make a three dimensional porous organic polymer would be a
the green emission is further supported by –OMe substituted o- novel approach to provide rigidity to the chromophore similar
7
MBDI-TEB-CMP (λem = 440 nm) and also validated theoretically.
to protein scaffold. Therefore, the topological effect of the 3D
porous matrices and chemical modifications in the
chromophore, together would facilitate to restrict the rotation
of the aryl - alkene bond of the chromophore and opening the
radiative pathways. However, to the best of our knowledge,
the gfp chromophore based extended porous organic polymer
The green fluorescent protein (gfp) and its mutants have been
extensively studied as biomarker and revolutionized the
1
molecular biology. The chromophore, p-hydroxybenzylidene-
imidazolinone (p-HBDI) immobilized to the protein
-barrel
cavity, undergoes excited state proton transfer (ESPT) with the
protein environment and demonstrates green emission with
high quantum efficiency (0.79) and longer lifetime (3.03 ns).
However, the isolated p-HBDI chromophore is virtually non-
fluorescent due to the ultrafast internal conversion through
2a, 8
materials is yet to be documented.
As the fluorescence
performances of these chromophores are sensitive to the
surrounding environment, therefore, porous scaffold would
provide a platform to interact chromophore with solvents of
different polarity in a confined space that would modulate
2
two torsional modes along either the exocyclic C
−
C or the
9
ESPT and corresponding emission properties.
C=
C bond that opens up the non-radiative pathways. In-depth
Here, we demonstrate the anchoring of gfp chromophore
analogues in conjugated microporous polymers via
Sonogashira – Hagihara coupling reaction and explore their
photophysical properties in detailed. First, we have
synthesized and crystallized two new tri-iodo substituted
analogues of the gfp chromophore, namely (Z)-4-(2-hydroxy-
experimental and theoretical studies have been performed to
understand and mimicking the intrinsic photophysical
properties of the gfp chromophore and its analogues without
3
the confinement effect of the

-barrel. There are several
approaches, for instances; metal complexation, fusion of aryl –
alkene bond, intra-molecular hydrogen bonding etc., are
reported to inhibit the cis-trans isomerisation between the
benzylidene-imidazolinone core of gfp chromophore
3
5
,5-diiodobenzylidene)-1-(4-iodophenyl)-2-methyl-1H-imidazol-
(4H) -one (o-HBDI-I3) and (Z)-4-(3,5-diiodo-2-
2a, 2c, 3e, 4
(a)
analogues for fabricating novel fluorescent materials.
However, these approaches are mainly subjected to the
structural modification to recover as well as enhance the
emission in the isolated chromophore. In recent works, the gfp
chromphore has been immobilized to the porous metal-
organic framework systems that reduces the cis-trans
isomerisation due to the confined space of the rigid scaffold
o-HBDI-I3
o-MBDI-I3
(
b) 1.0
o-HBDI-I3
1.0
0.8
0.6
0.4
o-MBDI-I3
Absorbance
Fluorescence
Absorbance
Fluorescence
0
.8
0
.6
5
and mimicked the green emission of the gfp. Despite of
significant efforts, recovery of the native gfp emission
0.4
0.2
0.2
0
.0
300
0
.0
3
400
500
600
700
00
400
500
600
700
Wavelength (nm)
Wavelength (nm)
*
Molecular Materials Laboratory, Chemistry and Physics of Materials Unit, School of
Advanced Materials (SAMat),
Figure 1: (a) ORTEP diagram for o-HBDI-I3 (left) and o-MBDI-I3 (right) at 50% probability
level; (b) UV-Vis and photoluminescence spectra for o-HBDI-I3 (left) and o-MBDI-I3
Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore-560064, India
E-mail: tmaji@jncasr.ac.in;
Tel: 91-8022082826
(
right), respectively. Photographs of o-HBDI-I3 (left) and o-MBDI-I3 (right) in methanol
under UV light.
Electronic Supplementary Information (ESI) available: DOI: 10.1039/x0xx00000x
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 1
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methoxybenzylidene)-1-(4-iodophenyl)-2-methyl-1H-imidazol-
Journal Name
(iodine) in monomers reduces the internal conversion and
View Article Online
5
(4H)-one (o-MBDI-I3). The o-HBDI-I3 emits in the red region subsequently offers the radiative pathwaDyO.1 I2: 10.1039/C9CC00357F
due to the intra-molecular ESPT, whereas o-MBDI-I3 shows
Further, o-HBDI-I3 and o-MBDI-I3 used as tri-connected
cyan - green emission. These chromophores, o-HBDI-I3 and o- nodes and assembled with 1,3,5-triethynylbenzene (TEB) via
12
MBDI-I3 are further used for the synthesis of CMPs, namely o-
C−C coupling to form two new CMPs, o-HBDI-TEB-CMP and
HBDI-TEB-CMP and o-MBDI-TEB-CMP, respectively (see o-MBDI-TEB-CMP, respectively (Figure 2, see SI for detail). The
supporting information (SI), Figure 2). Interestingly, emission FT-IR spectra for both the polymers are similar except a
-1
and excited state lifetime of o-HBDI-TEB-CMP in methanol are characteristic hydroxyl peak (O
−H) at 3386 cm for o-HBDI-
found to be similar to the wild type gfp (wt-gfp). However, TEB-CMP (Figure S12&S13). The presence of an alkyne peak at
-
1
13
absence of hydroxy group in o-MBDI-TEB-CMP results in 2202 cm confirm the formation of CMPs. Solid state C-NMR
significantly blue shifted emission but structural rigidity spectra are found to be similar for both the polymers (Figure
ensures the longer excited state lifetime in this case as well.
The gfp chromophore analogues, o-HBDI-I3 and o-MBDI-I3 unsymmetrical alkyne carbons (C
are synthesized and crystallized in the monoclinic crystal distributed between 120 – 155 ppm. Keto carbon of the
system with space group C2/c and P2 /c, respectively (Table imidazolinone ring ( O) is deshielded and appeared at 165
ST1–ST3). The crystal structure of o-HBDI-I3 shows an intra- ppm. A distinguished and characteristic peak for methoxy
molecular hydrogen bonding (O N) which is absent in the carbon ( OCH ) in o-MBDI-TEB-CMP is present at 52 ppm. This
2). Two peaks at 89.9 and 105.8 ppm are attributed to
≡
C). Aromatic carbons are
1
−C=
−
H⋯
−
3
o-MBDI-I3 due to methoxy substitution. Notably, methoxy peak is absent in the case of o-HBDI-TEB-CMP. Thermo-
group is appeared trans to imidazolinone (Figure 1). Moreover, gravimetric analyses (TGA) suggest thermal stability up to 300
both monomers show extended three-dimensional supra- °C for both the polymers (Figure S10). The morphology of the
molecular structures based on halogen-halogen interaction CMPs are studied using Field Emission Scanning Electron
(
I
⋯
I = 3.8 Å) and non-covalent (C
π) interactions (Figure S3 – S5). The photophysical (TEM) measurement. FE-SEM analyses reveals the assembly of
studies are carried out for both, o-HBDI-I3 and o-MBDI-I3 and irregular shaped flaky particles and such morphology was also
−H⋯O, C=O⋯π and Microscopy (FE-SEM) and Transmission Electron Microscopy
C−H⋯
4b
13
found akin to the similar compounds, reported in literature.
observed in previously reported CMPs. Furthermore, high
The absorption spectrum of o-HBDI-I3 in methanol shows two resolution TEM analysis also confirms such morphology in both
2a
absorption maximum at 360 and 400 nm. Upon excitation at polymers (Figure 2). Powder XRD is performed for both the
00 nm, the emission is found in the red region with maximum polymers in the range of 2 value 2 - 40° (Figure 2). A broad
at 632 nm due to the intra-molecular ESPT from –OH to imino peak at 2 20.8° in o-HBDI-TEB-CMP and 20.3° in o-MBDI-
4


=
nitrogen of the imidazolinone ring (see SI for detail, Figure 1 & TEB-CMP indicates the absence of long-range ordering in the
S8).4
d, 10
We have performed theoretical calculation which also polymers.
Both the polymers are subjected to N
feasible process in the o-HBDI-I3 (Figure S22&23). Further, K) adsorption studies to measure the permanent porosity and
owing to the intra-molecular ESPT, the solvatochromic show non-porous with respect to N adsorption. However,
uptake about 100 mL/g (Figure 2) is
reveals that the intra-molecular ESPT is thermodynamic
2 2
(77 K) and CO (195
2
11
behaviour of the o-HBDI-I3 is investigated in different type I profiles with CO
2
solvents (hexane, chloroform, acetonitrile, ethyl acetate, found for both the polymers. The Langmuir surface area for o-
tetrahydrofuron, dimethyl suphoxide, dimethyl formamide and HBDI-TEB-CMP and o-MBDI-TEB-CMP is found to be 320.7 and
2
methanol) ranging from non-polar to polar solvents. The 278 m /g, respectively. The pore sizes calculated by NLDFT
solvent dependent emission is observed between 610 – 650 method are found to be 1.40 nm and 1.43 nm for o-HBDI-TEB-
nm in these solvents (Figure S8b). The role of intra-molecular CMP and o-MBDI-TEB-CMP, respectively, which suggest
ESPT in the photophysics of the o-HBDI-I3 is further supported microporous nature for both polymers (Figure S14). Solvent
4
b
by the compound o-MBDI-I3. Absorption maximum for the o- adsorption studies are performed to understand the nature of
MBDI-I3 is observed at 360 nm in methanol. Upon excitation at pore surfaces (Figure S19&S20). The o-HBDI-TEB-CMP display
3
60 nm, the o-MBDI-I3 demonstrates the emission maximum high uptake of methanol (120 mL/g at 295 K) and low uptake
at 470 nm due to absence of ESPT phenomenon (Figure 1). of benzene (28 mL/g at 298 K). However, the o-MBDI-TEB-CMP
However, o-MBDI-I3 also shows solvent dependent emission show similar uptake of methanol and benzene (50 – 58 mL/g).
due to interaction of solvent molecules with the imino This indicates that the o-HBDI-TEB-CMP has more hydrophilic
nitrogen of the imidazolinone ring. The emission of o-MBDI-I3 pore surfaces in comparison to o-MBDI-TEB-CMP due to
was observed between 450 nm – 510 nm with the same set of hydroxy substitution in the former CMP. This study
11
solvents as mentioned above (Figure S9). The red and cyan demonstrates the facile diffusion of solvents molecules of
emission for both the compounds could easily be discerned by different polarity in the CMPs.
naked eyes (Figure 1). The absolute quantum yield (Q.Y.) for o- The photophysical studies of porous polymers, o-HBDI-TEB-
HBDI-I3 and o-MBDI-I3 in methanol is found to be 0.56% and CMP and o-MBDI-TEB-CMP are carried out in detail (Figure 3
0
.29%, respectively, which is better than several previous and S15 – 18). As the gfp chromophore is sensitive to the
2a, 4b
reports.
This is because the heavy atom substitution surrounding environments, and here both the polymers show
uptake of polar and non-polar solvents, thus emission of the
2
| J. Name., 2012, 00, 1-3
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Journal Name
a)
COMMUNICATION
e
o-HBDI-TEB-CMP
o-MBDI-TEB-CMP
View Article Online
(
(b)
(c)
DOI: 10.1039/C9CC00357F
e = aromatic carbons
d
e = aromatic carbons
a
g f
c
b
2
00 180 160 140 120 100 80 60 40 20
0
2
00 180 160 140 120 100 80 60 40 20
Chemical shift (ppm)
0
Chemical shift (ppm)
o-MBDI-TEB-CMP
1
00
o-HBDI-TEB-CMP
120
100
80
CO2 adsorption
(
h)
CO2 desorption
(
i)
o-HBDI-TEB-CMP
o-MBDI-TEB-CMP
80
60
40
20
0
(j)
CO2 adsorption
CO2 desorption
N2 adsorption
N2 desorption
(
d)
(e)
(f)
(g)
60
N2 adsorption
4
0
2
N desorption
20
0
1
00 nm 100 nm
5
10 15 20 25 30 35 40

0.0
0.2
0.4
0.6
0.8
1.0
0.0
0.2
0.4
0.6
0.8
1.0
Relative Pressure (P/P0)
Relative Pressure (P/P0)
2
Figure 2: (a) Synthetic scheme for o-HBDI-TEB-CMP (left) and o-MBDI-TEB-CMP (right); (b–j): Characterization of CMPs: (b) and (c) solid state 13C–NMR for o-HBDI-
TEB-CMP and o-MBDI-TEB-CMP, respectively; (d) and f) FE-SEM images for o-HBDI-TEB-CMP and o-MBDI-TEB-CMP, respectively; (e) and (g) TEM images for o-HBDI-
2 2
TEB-CMP and o-MBDI-TEB-CMP, respectively; (h) PXRD; N (77 K) and CO (195 K) adsorption for (i) o-HBDI-TEB-CMP and (j) o-MBDI-TEB-CMP.
polymers can be modulated by changing the solvents media. A in the green region. The Q.Y. for o-HBDI-TEB-CMP is measured
stable dispersion of o-HBDI-TEB-CMP in methanol (Figure S18) in methanol and found to be 0.82% which is higher due to
shows broad absorption due to π – conjugated network with a structural rigidity of chromophore4b, 5a in comparison to o-
4b
maximum absorption at 383 nm (Figure S15a). Upon excitation HBDI-I3. The pH effect has also been studied for the o-HBDI-
at 390 nm, it exhibits green emission at 515 nm in methanol. TEB-CMP in methanol (Figure S21). In acidic medium, pH 3, it
Further, the excitation spectrum collected at 515 nm show the becomes weakly fluorescent due to protonation of
=
15
maximum at 400 nm (Figure 3). Interestingly, upon excitation imidazolinone ring. While at pH
at 390 nm in different solvents, ranging from non-polar to would be deprotonated and subsequently anionic form shows
polar solvents, the o-HBDI-TEB-CMP shows solvent significantly blue shifted emission (λmax 430 nm). Further,
= 10, the hydroxyl group
a
=
dependent emission between 475 – 515 nm (Figure S16). Non- with the aim to reprotonate hydroxide ion, the pH of solution
polar (chloroform and benzene) and polar (acetone, DMF and has brought down from 10 to 7 by acidifying with 0.2 N HCl.
DMSO) solvents result in the emission at 475 (
2) nm, respectively. Notably, the excitation and emission pH
spectrum of polymer o-HBDI-TEB-CMP in methanol is closer to hydroxyl group play very crucial role in the emission property
±
2) and 485 We observed a red shifted emission (λmax
= 475 nm) at neutral
(
±
=
7 in comparison to the pH 10. This endorses that the
=
1a
the wild type gfp chromophore. The significant shifting in the of o-HBDI-TEB-CMP.
emission of polymer in comparison to monomer is subjected
To get further insight of the hydroxyl group effect in the
to the topological effct in former case. Moreover, the metal emission, we studied photophysical properties of the o-MBDI-
free organic scafold is advantageous to ruled out possibility of TEB-CMP (Figure 3) which is expected to be similar to the
metal contribution in the obtained emission of polymer. To anionic form of the o-HBDI-TEB-CMP. The UV-Vis spectrum of
understand the large hypsochromic shift in emission of o- the o-MBDI-TEB-CMP in methanol displays a broad absorption
HBDI-TEB-CMP in comparison to o-HBDI-I3, we have with a maximum at 360 nm (Figure S15). Upon excitation at
performed density functional theory (DFT) calculations for enol 360 nm, the emission maximum is observed at 440 nm.
and keto form of a repeating unit of polymer in ground as well
1
0
0
0
0
.0
.8
.6
.4
.2
o-HBDI-TEB-CMP
1
(
a)
oHBDI-I3
Prompt
oHBDI-TEB-CMP
Excitation in MeOH
Emission in MeOH
(b)
as in excited state (Figure 4 & S24 – S25). We observed that
the excited state intermolecular proton transfer is high energy
process by 3.7 kcal/mol due to twisting of the benzylidine ring
0
.1
0
.01
1
E-3
E-4
(6°) with the plane of imidazolinone ring in o-HBDI-TEB-CMP
1
(see supporting info. for detail). Thus, intramolecular ESPT
0.0
3
50 400 450 500 550 600 650 700
Wavelength (nm)
0
5
10 15 20 25 30 35
Time (ns)
does not occur in o-HBDI-TEB-CMP and display significant
hypsochromic shift in the emission in comparison to the
intramolecular ESPT driven emission of o-HBDI-I3. However,
1
0
0
.0
(c)
o-MBDI-TEB-CMP
Excitation_MeOH
Emission_MeOH
1
oMBDI-I3
Prompt
oMBDI-TEB-CMP
(d)
.8
.6
0.1
presence of
−
OH in the o-HBDI-TEB-CMP facilitates the inter-
0.01
1
4
0.4
0.2
molecular ESPT with polar solvents. The extent of ESPT
depends on the polarity as well as on solvent size. Considering
both the factors, hydrophilic pore surfaces of o-HBDI-TEB-CMP
allow the effective diffusion of methanol as also realized in
1
E-3
1
E-4
3
00 350 400 450 500 550 600 650
Wavelength (nm)
0
5
10 15 20 25 30 35
Time (ns)
Figure 3: (a) and (c) excitation and emission spectra recorded in methanol for o-HBDI-
adsorption study. Moreover, methanol is known to form TEB-CMP; and o-HBDI-TEB-CMP, respectively; Excited state lifetime recorded upon
1
4b
excitation at 370 nm in methanol (b) for –OH containing and (d) for OMe- containing
monomer and polymer. Photographs of o-HBDI-TEB-CMP (above) and o-MBDI-TEB-CMP
external H-bonding that leads to better inter-molecular ESPT
and subsequently modulate the emission of o-HBDI-TEB-CMP
(
below) under UV light in methanol.
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COMMUNICATION
Journal Name
o-HBDI-TEB-CMP
porous organic polymer systems with tunable emission.
View Article Online
DOI: 10.1039/C9CC00357F
AS thanks SERB, DST, India for NPDF (SERB project No.
PDF/2016/002324). TKM is grateful to the DST (Project No.
MR-2015/001019 and TRC-DST/C.14.10/16-2724,), Govt. of
India and JNCASR for financial support.
No Intra-molecular ESPT
(
c)
(
E.S.)
(
E.S.)
3.7 kcal/mol
(
b)
Conflicts of interest
There are no conflicts to declare.
3
88
6
nm
32
nm 526
nm
Notes and references
1. (a) M. Zimmer, Chem. Rev., 2002, 102, 759; (b) R. Y. Tsien,
Annu Rev Neurosci., 1989, 12, 227.
(
d)
(
G.S.)
2
.9 kcal/mol
(
a)
(
G.S.)
keto form
enol form
Figure 4: Schematic diagram for theoretically obtained energy differences in 2. (a) H. Deng and X. Zhu, Mater. Chem. Front., 2017, 1, 619; (b)
methanol for enol and keto form of repeating unit of o-HBDI-TEB-CMP. (a) & (d) M. Ormo, A. B. Cubitt, K. Kallio, L. A. Gross, R. Y. Tsien and S. J.
represent ground state (G.S.) and (b) & (c) represent excited state (E.S.).
Remington, Science, 1996, 273, 1392; (c) Y.-H. Chen, R. Sung and
K. Sung, J. Phys. Chem. A, 2018, 122, 5931; (d) C.-C. Hsieh, P.-T.
Chou, C.-W. Shih, W.-T. Chuang, M.-W. Chung, J. Lee and T. Joo,
The absorption and emission spectrum for the repeating unit
of o-MBDI-TEB-CMP has also been predicted theoretically and J. Am. Chem. Soc., 2011, 133, 2932.
found to be at 366 and 418 nm, respectively (Figure S26&S27). 3. (a) M.-S. Tsai, C.-L. Ou, C.-J. Tsai, Y.-C. Huang, Y.-C. Cheng, S.-
S. Sun and J.-S. Yang, J. Org. Chem., 2017, 82, 8031; (b) C.
Further, the excitation spectrum of the o-MBDI-TEB-CMP
McLaughlin, M. Assmann, M. A. Parkes, J. L. Woodhouse, R.
collected at 440 nm is appeared at 360 nm. Solvatochromic
Lewin, H. C. Hailes, G. A. Worth and H. H. Fielding, Chem. Sci.,
behaviour of o-MBDI-TEB-CMP has studied upon excitation at
60 nm and emission maximum is found to be between 430
2
017, 8, 1621; (c) L. M. Tolbert, A. Baldrige, J. Kowalik and K. M.
3
4
−
Solntsev, Acc. Chem. Res., 2012, 45, 171; (d) A. Baldridge, K. M.
50 nm (Figure S17) due to interaction of imino nitrogen of Solntsev, C. Song, T. Tanioka, J. Kowalik, K. Hardcastleb and L. M.
Tolbert, Chem. Commun., 2010, 46, 5686; (e) Y.-H. Hsu, Y.-A.
imidazolinone ring with solvent of different polarities. The blue
emission of o-MBDI-TEB-CMP can easily be seen by naked eyes
under UV light (Figure 3). The absolute quantum yield of o-
MBDI-TEB-CMP in methanol is found to be 0.24%.
Chen, H.-W. Tseng, Z. Zhang, J.-Y. Shen, W.-T. Chuang, T.-C. Lin,
C.-S. Lee, W.-Y. Hung, B.-C. Hong, S.-H. Liu and P.-T. Chou, J. Am.
Chem. Soc., 2014, 136 11805.
4. (a) E. Carrascosa, J. N. Bull, M. S. Scholz, N. J. A. Coughlan, S.
The excited state lifetime measurements have performed Olsen, U. Wille and E. J. Bieske, J. Phys. Chem. Lett., 2018, 9,
2
647; (b) K.-Y. Chen, Y.-M. Cheng, C.-H. Lai, C.-C. Hsu, M.-L. Ho,
in methanol (Figure 3 & Table ST5). The lifetime data for both
the monomers is fitted using bi-exponential function and
exhibit short excited state lifetime due to the cis-trans
G.-H. Lee and P.-T. Chou, J. Am. Chem. Soc., 2007, 129, 4534; (c)
L. Wu and K. Burgess, J. Am. Chem. Soc. , 2008, 130, 4089; (d) X.-
Y. Liu, X.-P. Chang, S.-H. Xia, G. Cui and W. Thiel, J. Chem. Theory
4a
isomerisation. The average decay time for o-HBDI-I3 and o- Comput., 2016, 12, 753; (e) G.-J. Huang, J.-H. Ho, C. Prabhakar,
MBDI-I3 is found to be 0.12 ns and 0.01 ns, respectively. Intra- Y.-H. Liu, S.-M. Peng and J.-S. Yang, Org. Lett., 2012, 14, 5034.
5
. (a) D. E. Williams, E. A. Dolgopolova, P. J. Pellechia, A.
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2
In conclusion, we have demonstrated design, synthesis and
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| J. Name., 2012, 00, 1-3
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Table of Content
DOI: 10.1039/C9CC00357F
Gfp chromophore integrated conjugated microporous polymers:
Topological and ESPT effect on emission properties
Ashish Singh, Debabrata Samanta, Mrinal Boro and Tapas Kumar Maji*
Covalent linking of red emissive gfp chromophore in the conjugated microporous polymer (CMP)
display green emission similar to the natural gfp due to topological effect.
ESPT
No ESPT
OMe
O
O
N
N
N
N
OH
OMe
HO
N
N
N
O
N
O
N
N
O
O
N
N
OH
MeO
o-HBDI-TEB-CMP
o-MBDI-TEB-CMP
I
O
I
O
N
O
N
I
I
OH
N
N
I
I
o-HBDI-I3
o-MBDI-I3