Highly Luminescent Microporous Organic Polymer with Lewis Acidic Boron Sites on the Pore Surface: Ratiometric Sensing and Capture of F- Ions

Article abstract of DOI:10.1002/chem.201500406

Reversible and selective capture/detection of F^- ions in water is of the utmost importance, as excess intake leads to adverse effects on human health. Highly robust Lewis acidic luminescent porous organic materials have potential for efficient

Full text of DOI:10.1002/chem.201500406

DOI: 10.1002/chem.201500406
Full Paper
&
Microporous Materials
Highly Luminescent Microporous Organic Polymer with Lewis
Acidic Boron Sites on the Pore Surface: Ratiometric Sensing and
À
Capture of F Ions
[a]
[b]
[a]
[c]
Venkata M. Suresh, Arkamita Bandyopadhyay, Syamantak Roy, Swapan K. Pati, and
[a]
Tapas Kumar Maji*
À
À
Abstract: Reversible and selective capture/detection of F
selective turn-on sensing and capture of F ion are reported.
ions in water is of the utmost importance, as excess intake
leads to adverse effects on human health. Highly robust
Lewis acidic luminescent porous organic materials have po-
The presence of a vacant p orbital on the boron center of
p
BMOP results in intramolecular charge transfer (ICT) from the
linker to boron. BMOP shows selective turn-on blue emission
À
À
tential for efficient sequestration and detection of F ions.
for F ions in aqueous mixtures with a detection limit of
Herein, the rational design and synthesis of a boron-based,
Lewis acidic microporous organic polymer (BMOP) derived
from tris(4-bromo-2,3,5,6-tetramethylphenyl)boron nodes
and diethynylbiphenyl linkers with a pore size of 1.08 nm for
2.6 mm. Strong B–F interactions facilitate rapid sequestration
of F by BMOP. The ICT emission of BMOP can be reversibly
À
regenerated by addition of an excess of water, and the poly-
mer can be reused several times.
Introduction
hand, metal complexes and small organic molecular sensors
À
for F detection in solvents such as H O, THF, and DMF have
2
À
Reversible and selective detection/capture of excess F ions is
been reported, but they suffer from poor reversibility, low recy-
[
6]
important due to its impact on human health and the environ-
clability, or difficulty regeneration. Reversibility and easy recy-
clability are of the utmost importance for the commercializa-
tion and industrial application of a sensor. In this context, the
[
1,2]
À
ment.
The World Health Organization recommends F con-
tents in drinking water of less than 1.5 ppm, and overexposure
is known to cause dental fluorosis, osteoporosis, and other se-
À
confined nanospaces enclosed by a high density of F binding
[1]
rious health problems. Although several methods for the de-
sites with fluorescence read-out signaling ability of solid
À
[7]
tection and sequestration of F ions have appeared, low selec-
porous materials have potential for rapid and selective detec-
À
tivity, poor recyclability, leaching, and weak or no analytical
signal output demand the development of new materials that
show both selective and reversible readout fluorescence sig-
tion of F ions. The insoluble nature of solid porous materials
À
facilitates heterogeneous-phase detection of F ions and
allows easy recovery of the sensor material from aqueous solu-
tions. Sensors based on inorganic–organic hybrid systems such
as metal–organic frameworks (MOFs) have been reported, but
their poor hydrolytic stability and limited regenerability due to
À
[3]
nals and sequestration of F ions. Recently, small-molecule
sensors having vacant Lewis acidic centers have been studied
for colorimetric and fluorimetric sensing of small anions such
À
[4]
À
as F in organic solvents. However, they often suffer from
very low density of active sites and vulnerability to microenvir-
onmental conditions such as solvent, and the counterion-pair-
disintegration of the framework on F binding limits their ap-
[
8]
plication. In this respect, porous organic polymer solid ad-
[
9]
sorbents such as conjugated microporous polymers (CMPs),
À [5]
[10]
ing effect limits real-time monitoring of F . On the other
pioneered by Cooper et al., have great potential for selective
À
sensing and capture of F ions, owing to their strong fluores-
[
a] V. M. Suresh, S. Roy, Prof. Dr. T. K. Maji
Molecular Materials Laboratory
Chemistry and Physics of Materials Unit (CPMU)
Bangalore-560064 (India)
cence signaling ability and pronounced chemical/thermal and
hydrolytic stability due to strong covalent linkages between
their building blocks. Flexibility in design and the availability of
large number of organic struts provides functionalized pore
E-mail: tmaji@jncasr.ac.in
[
11]
[
b] A. Bandyopadhyay
surfaces for desired applications. In addition, the ability to
host various guests in the confined environment of nanopores
offers guest-responsive modulation of optical and electronic
New Chemistry Unit (NCU), Bangalore-560064 (India)
[
c] Prof. Dr. S. K. Pati
Theoretical Sciences Unit (TSU)
Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR)
Bangalore-560064 (India)
[12]
properties and can be exploited for sensing applications.
[
13]
Among the CMPs,
heteroatom-containing conjugated
porous polymers in which electron-donor atoms such as N are
replaced by electron-deficient B centers have potential for the
Supporting information for this article is available on the WWW under
http://dx.doi.org/10.1002/chem.201500406.
Chem. Eur. J. 2015, 21, 10799 – 10804
10799
ꢀ 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Full Paper
À
detection of F ions. Conjugation through the vacant p orbital
on boron would introduce characteristic photophysical and
electronic properties in the polymer. Therefore such a polymer
would have a potential as a nonlinear optical material, as an
electroluminescent and charge transporter in organic light-
[14]
emitting diodes (OLEDs).
design and synthesis of a boron microporous organic polymer
BMOP) containing methyl-protected triarylborane as node and
Herein, we report the rational
(
diethynylbiphenyl as linker for selective and turn-on fluores-
À
cent sensing and sequestration of F ions with excellent recy-
clability from aqueous solution. High-density Lewis acidic B
centers throughout the polymer facilitate selective and rapid
detection of small anions, which would significantly obstruct
intramolecular charge transfer (ICT) from the diethynylbiphenyl
linker to the empty pp orbital of boron. The ICT emission
À
changes to intense blue emission on binding of F ion to the
boron center at levels as low as 0.2 ppm in aqueous binary
mixtures. Furthermore, strong covalent linkages in the polymer
provide high hydrolytic stability and easy regeneration of the
sensor on addition of an excess of water.
1
3
Figure 1. C CP/MAS solid-state NMR spectrum of BMOP confirming the
linkage of node and linker through a CÀC bond.
spectrum (Supporting Information, Figure S4), which showed
a B 1s peak centered at 189.90 eV and a Br 3p3/2 peak at
184.45 eV, suggested the presence of boron and free terminal
Results and Discussion
[
18]
bromine of the triarylborane node in BMOP. Powder XRD
measurements showed a broad peak at 208 indicating amor-
phous nature of BMOP (Supporting Information, Figure S5).
SEM images showed formation of clustered spherical parti-
cles of size varying from 100 to 300 nm (Supporting Informa-
tion, Figure S6). TEM images also revealed the presence of clus-
tered particles (Supporting Information, Figure S7) and, at
higher magnification, the presence of micropores in the parti-
cle (Figure 2a). Thermogravimetric analysis of BMOP showed
no appreciable weight loss up to 2808C, and further heating
resulted in steady weight loss (50%) up to 7208C (Supporting
Information, Figure S8), and constant mass was observed up to
Synthesis and characterization
0
BMOP was synthesized by Pd /CuI-catalyzed Sonogashira CÀC
coupling between tris(4-bromo-2,3,5,6-tetramethylphenyl)bor-
on nodes (Supporting Information, Figure S1) and 4,4’-diethy-
nylbiphenyl linkers (Supporting Information, Figure S2), as
shown in Scheme 1. The FTIR spectrum of BMOP, which shows
À1
bands at 980, 1600, and 2100 cm corresponding to the CÀB,
1
0008C. These results suggest the absence of any traces of
[
Pd(PPh ) ] catalyst, and the remaining mass can be attributed
3
4
0
to the presence of oxides of boron and Pd nanoparticles.
Such mass constancy is also observed in covalent organic
[
19]
frameworks and metal–organic frameworks.
N2 adsorption
measurements at 77 K showed a type I adsorption profile with
appreciable uptake in the lower-pressure range, and the final
À1
uptake was 207 mLg (Figure 2b). Application of the BET
model to the N isotherm in the range of P/P =0.01–0.3 yield-
Scheme 1. Synthesis of BMOP by Sonogashira CÀC coupling between tris(4-
2
0
2
À1
bromo-2,3,5,6-tetramethylphenyl)boron and diethynylbiphenyl.
ed a surface area of 390 m g . A nonlocal DFT model fitted to
the N2 adsorption isotherm gave an average pore size of
1.08 nm and thus signified microporous nature of the polymer
(Supporting Information, Figure S9). BMOP showed a CO2
uptake capacity of 90 mL (18 wt%) at 195 K up to 1 atm (Fig-
ure 2b, inset) and 60 mL (12 wt%) at 273 K up to 30 bar (Sup-
porting Information, Figure S10).
[
12a,15]
C=C, and CꢀC stretching vibrations, respectively
(Support-
ing Information, Figure S3), confirmed the presence of both
node and linker moieties in the polymer. Furthermore, the
13
solid-state C CP/MAS NMR spectrum shows a moderate
signal at 90 ppm assigned to C of the CꢀC bond, suggests
bonding of the triarylborane node and 4,4’-diethynylbiphenyl
linker (Figure 1). Other peaks ranging from 120–150 ppm can
Photophysical studies
[12a,16]
be assigned to the aromatic C atoms of phenyl rings,
and
the peak at 19 ppm to aliphatic methyl substituents of the
BMOP is a dark green compound in contrast to the white crys-
talline tris(4-bromo-2,3,5,6-tetramethyl phenyl)boron and 4,4’-
diethynylbiphenyl precursors. The absorbance of BMOP is
[
6a,17]
phenyl rings.
The presence of boron in BMOP was con-
firmed by X-ray photoelectron spectroscopy (XPS). The XP
Chem. Eur. J. 2015, 21, 10799 – 10804
www.chemeurj.org
10800
ꢀ 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Full Paper
dicates that the excited state is stabilized by polar solvents
due to the high dipole moment. Furthermore, no changes in
excitation spectra were observed on changing the solvent po-
larity, and this suggests weak coupling between donor and ac-
ceptor in the ground state (Supporting Information, Fig-
ure S13). The ICT behavior of BMOP was further studied by per-
forming DFT calculations on the boron precursor and the
smallest unit of the polymer (Figure 3a) by using the B3LYP
Figure 3. a) HOMO–LUMO energy level diagram of tris(2,3,5,6-tetramethyl-4-
bromophenyl) boron and the smallest unit of BMOP. b) ESP plot of the small-
À
est unit of BMOP after F binding (red and blue regions indicate high and
low electron density, respectively). c) Energy-minimized structure of
À
F @BMOP showing the changes in bonding environment around the boron
center. Red: B, blue: C, green: F, silver: H.
functional and 6-31+G(d) basis set, as implemented in Gaussi-
an 09. Molecular orbital plots of the node and smallest unit of
BMOP show that HOMO and LUMO are mainly localized on the
phenyl rings and boron center, respectively. TDDFT calculations
suggested that the ground state and optically allowed excited
state correspond to the HOMO and LUMO, respectively. This
Figure 2. a) TEM image of BMOP showing micropores at higher magnifica-
tion (inset: electron-diffraction pattern). b) N adsorption isotherms of BMOP
at 77 K (inset: CO adsorption profile at 195 K).
2
2
clearly suggests that ICT from the linker to the empty p orbi-
p
broad and features two major UV/Vis absorption bands at 350
tal of boron occurs. The optical absorption of the smallest unit
(421.2 nm, f=1.2151) theoretically predicted by TDDFT calcula-
tions compares fairly well with the experimental value
(410 nm), and no changes in absorption maxima are observed
with changing solvent polarity (Supporting Information, Fig-
ure S13). Furthermore, electrostatic potential (ESP) maps of the
smallest unit of BMOP clearly reveal that the boron center is
highly electron deficient (Supporting Information, Figure S14).
and 410 nm, which can be ascribed to p–p* transition of the
linker part and p–p (B) electron transition from the linker to
p
the empty p orbital of boron, respectively (Supporting Infor-
mation, Figure S11). In contrast to the blue emission of the
linker and non-emissive behavior of tris(4-bromo-2,3,5,6-tetra-
methylphenyl)boron, BMOP shows strong green emission with
a maximum at 520 nm (Supporting Information, Figure S11),
and the excitation spectrum shows two resolved bands at 350
and 410 nm. This large redshift in emission of BMOP clearly
suggests interaction between the extended linker (donor) and
the boron center (acceptor) through ICT via conjugation. The
ICT process was validated by solvent-dependent emission fea-
tures of the polymer; in a nonpolar solvent such as hexane,
BMOP shows local excited-state emission with a maximum at
Fluoride sensing and capture
On the basis of the principle that boron with empty p orbital
p
in BMOP would accept electrons from anions, which would
perturb the ICT process and induce changes in the fluores-
À
cence signal, we studied the effect of F ions on the ICT emis-
4
10 nm originating from the extended linker, whereas in
sion of BMOP. No visible color change was observed in the
À
a highly polar solvent such as water the emission maximum is
redshifted to 520 nm and assigned to ICT (Supporting Informa-
tion, Figure S12). The dependence of the emission maxima of
the polymer on solvent polarity demonstrates strong coupling
between donor and acceptor in the excited state. This strong
dependence of the emission maximum on solvent polarity in-
polymer on addition of F ions. Initial studies were done on
BMOP (5 mm) dispersed in THF, and the changes in the emis-
À
sion of BMOP on incremental addition of F in the form of
tetra-n-butylammonium fluoride (TBAF, 13 mm) in THF were re-
corded. As shown in Figure S15 of the Supporting Information,
the intensity of the emission band at 520 nm corresponds to
Chem. Eur. J. 2015, 21, 10799 – 10804
www.chemeurj.org
10801
ꢀ 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Full Paper
À
À
decreased ICT on addition of F ions, and subsequently a blue
emission intensity at 410 nm on addition of F . The blue emis-
emission band appears at 420 nm and is enhanced with in-
sion is ascribed to p*–p emission of the extended linker (see
À
À
creasing amount of F ions. It is expected that, when F binds
to boron, ICT is blocked and ICT emission decreased; however,
excitation of the linker results in p*–p emission localized on
the extended linker, that is, the tetramethylphenyl-fused 1,4-di-
ethynylbiphenyl unit. To confirm that the blue emission result-
ed solely from the extended linker, we calculated its excited-
state optical properties. The modified extended linker shows
an emission peak at 411 nm (1.9820 eV; Supporting Informa-
tion, Figure S16), which is close to experimentally observed
blue emission (420 nm). Also, the orbital diagram (LUMO and
HOMO) confirms that this extended linker shows the character-
istic p*–p emission peak (S1!S0; Supporting Information, Fig-
ure S17), which further support the hypothesis that the strong
above). Nevertheless, the detection limit was observed to be
about 20 ppm. On the other hand, THF/H O in (9:1) is found to
2
À
be promising for detection of lower concentrations of F ions.
As shown in Figure 4b, similar blockage of ICT emission and
enhancement of blue emission from the linker was observed
À
on incremental addition of F (3.5 mm) to BMOP dispersed in
THF/H O. Strikingly, similar fluorescence response of BMOP was
2
À
observed down to very low concentrations of F . In the Stern–
Volmer plot showing the florescence response of BMOP versus
equivalents of fluoride ion (THF/H O 9:1, initial concentration
2
À
À4
of F : 4.5” 10 m; Supporting Information, Figure S21), the in-
tercept or detection limit was found to be 2.6 mm. Interestingly,
BMOP shows appreciable fluorescence response even at lower
À
À
À
blue emission of F -loaded MOP (F @BMOP) indeed originates
from the extended linker, which signifies its importance for
concentrations of F ions (final concentration: <2.6 mm) on
À
soaking F with a dispersion of BMOP in THF/H O for 15 min
2
À
turn-on sensing of F ions. The emission color of the solution
(Supporting Information, Figure S22). This delayed fluorescence
À
À
changes from green to intense blue on F binding (Supporting
response for such low concentrations of F may be attributed
À
Information, Figure S18). Furthermore, the ESP plot suggests
to the longer diffusion time of F ion to interact with boron
À
À
that, on complexation of F , the boron center loses its elec-
present in the polymer. The binding constant for F ion to
À
tron-deficient character, and F becomes the low-electron-den-
BMOP was calculated from fluorescence titration data to be 1”
4
À1
sity species (Figure 3b and Supporting Information, Fig-
10 m (Supporting Information, Figure S23). It is noteworthy
À
À
ure S19). We calculated the optimized structure for the F -
that BMOP is highly selective for F ions (Supporting Informa-
À
bound smallest unit (Figure 3c). The F ion is indeed strongly
tion, Figure S24) and shows no appreciable fluorescence re-
À
À
À
À
2À
bound to the boron center by donating electrons to boron.
sponse to other anions such as Cl , Br , I , NO , SO4 , and
3
À
À
2À
À
The BÀF distance of 1.47 Š in F @BMOP is close to that of BF
CO3 . This high selectivity of BMOP to F ions may be due to
the sterically crowded binding environment created by the
ortho-methyl groups of phenyl substituents around the boron
4
(
1.43 Š) and suggests strong interaction between B and F and
the corresponding geometry shown in Figure 3c.
À
[20]
À
Detection of F in water is a challenge. The World Health Or-
center.
The most striking feature of F ion sensing with
À
ganization recommends that F ion content in drinking water
BMOP is its reversibility and sample recovery. Owing to the
À
[4b]
be lower than 1.5 ppm. However, BMOP does not show signifi-
cant change in emission spectra on incremental addition of
fluoride ion in pure water due to high hydration enthalpy
large hydration enthalpy of the F ion, addition of an excess
À
of water to F @BMOP, regenerates the as-synthesized polymer
with complete restoration of green emission, and it can recov-
ered by simple centrifugation (Supporting Information, Fig-
ure S25).
(
Supporting Information, Figure S20). Hence, further experi-
ments were carried out in aqueous/organic solvent mixtures.
À
Initial experiments were done with BMOP (5 mm) dispersed in
To study the capability of BMOP in the sequestration of F ,
19
DMSO/H O (8:2) and titrated against TBAF (15 mm in DMSO/
we carried out F NMR spectroscopy on a solution of TBAF in
which BMOP was soaked (the insoluble nature of BMOP pre-
2
H O 8:2). Figure 4a shows a gradual decrease of the emission
2
11
intensity at 520 nm with simultaneous increase in the blue
vented our studying of B NMR spectral changes). A solution
of TBAF/[D ]DMSO (5 mm) was added to BMOP (0.1 mg), the
6
mixture allowed to stand for 60 s, and BMOP removed by cen-
trifugation. The clear solution thus obtained was analyzed for
À
19
free F ions by F NMR spectroscopy (Figure 5). As expected,
À
the signal intensity of free F in solution decreased drastically
within 60 s, and soaking for a further 60 s resulted in complete
loss of the F signal in the NMR spectrum. This clearly suggests
À
that the F ion is indeed captured within the porous polymer,
and its coordination to a boron center is evident from the blue
emission of BMOP under UV light (Figure 5, inset). Further-
1
more, H NMR spectra of the filtrate at different intervals did
not show any peaks related to integral parts of the polymer
and thus clearly suggested no disintegration of the polymer
À
on F ion binding (Supporting Information, Figures S26 and
Figure 4. Changes in fluorescence spectra of BMOP on incremental addition
À
S27). To further prove the capture of F by the polymer, we
À
of F ion in a) DMSO/H
2
O (8:2) and b) THF/H
2
O (9:1). Inset: images of BMOP
À
À
carried out elemental mapping of the F @BMOP powder isolat-
dispersed in THF/H
2
O under UV light before and after F addition and rever-
sibility of the color change.
ed by the centrifugation of the [D ]DMSO dispersion. Elemental
6
Chem. Eur. J. 2015, 21, 10799 – 10804
www.chemeurj.org
10802
ꢀ 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Full Paper
Conclusion
We have demonstrated the rational design and synthesis of
a Lewis acidic microporous organic polymer with high density
of functional boron centers as recognition sites for selective
À
detection of F . The extended conjugation of the linker
through duryl groups facilitated turn-on fluorescent sensing of
À
F ion by the obstruction of ICT. BMOP shows a low detection
limit, and strong boron–fluoride interactions allowed facile se-
À
questration of F ion. We further believe that BMOP with
strong ICT emission could find applications in OLEDs and in se-
questration of CO through Lewis acid–base interactions with
2
boron.
1
9
Figure 5. F NMR spectra of 5 mm TBAF solution in [D
6
]DMSO a) before,
Acknowledgements
b) after 60 s, and c) after 120 s of soaking with BMOP (trifluorotoluene as
standard). Inset: Change of emission color of BMOP dispersion to blue after
We thank Prof. C. N. R. Rao for his support and encouragement,
Mrs. Usha for TEM measurements, and NMR research centre
1
20 s under a UV lamp.
13
IISc, Bangalore, for solid-state C NMR measurements. V.M.S.
and S.R. thank CSIR and DST for fellowship and funding, T.K.M.
thanks DST, Government of India for financial support.
À
mapping showed a uniform distribution of F throughout the
À
polymer matrix, which confirms that the F ion is indeed cap-
tured by BMOP through strong anion–boron interactions in
the micropores of the polymer (Figure 6). These results clearly
Keywords: boron · Lewis acids · microporous materials ·
polymers · sensors
[
[
1] a) J. Fawell, K. Bailey, J. Chilton, E. Dahi, L. Fewtrell, Y. MagaraWorld
Health Organization (WHO). Fluoride in Drinking Water, IWA Publishing,
London, 2006.
2] a) P. Adler, Fluorides and Health, World Health Organization, Geneva,
1970; b) E.W. Rice, R. B. Baird, A. D. Eaton, L. S. Clesceri, Standard Meth-
ods for the Examination of Water and Wastewater, American Public
Health Association, American Water Works Association, Water Environ-
ment Federation, 1998.
[
[
3] a) S. Jagtap, M. K. Yenkie, N. Labhsetwar, S. Rayalu, Chem. Rev. 2012,
112, 2454–2466; b) B. Pan, J. Xu, B. Wu, Z. Li, X. Liu, Environ. Sci. Technol.
2013, 47, 9347–9354.
4] a) Z. M. Hudson, S. Wang, Acc. Chem. Res. 2009, 42, 1584–1596; b) C. R.
Wade, A. E. J. Broomsgrove, S. Aldridge, F. P. Gabba ¨ı , Chem. Rev. 2010,
110, 3958–3984.
[
[
5] E. Galbraith, T. D. James, Chem. Soc. Rev. 2010, 39, 3831–3842.
6] a) T. Liu, A. Nonat, M. Beyler, M. Regueiro-Figueroa, K. Nchimi Nono, O.
Jeannin, F. Camerel, F. Debaene, S. CianfØrani-Sanglier, R. Tripier, C.
Platas-Iglesias, L. J. Charbonni›re, Angew. Chem. Int. Ed. 2014, 53, 7259–
7263; Angew. Chem. 2014, 126, 7387–7391; b) S. Guha, S. Saha, J. Am.
Chem. Soc. 2010, 132, 17674–17677; c) X. Y. Liu, D. R. Bai, S. Wang,
Angew. Chem. Int. Ed. 2006, 45, 5475–5478; Angew. Chem. 2006, 118,
À
Figure 6. Energy-dispersive X-ray analysis of a) BMOP and b) F @BMOP,
À
showing the presence of F ions in the polymer. Elemental mapping of
F @BMOP for c) C and d) F , showing the presence of carbon and fluoride
ion, respectively, throughout the polymer matrix.
5601–5604; d) P. Bose, P. Ghosh, Chem. Commun. 2010, 46, 2962–2964;
À
À
e) R. Hu, J. Feng, D. Hu, S. Wang, S. Li, Y. Li, G. Yang, Angew. Chem. Int.
Ed. 2010, 49, 4915–4918; Angew. Chem. 2010, 122, 5035–5038.
[7] a) M. D. Allendorf, C. A. Bauer, R. K. Bhakta, R. J. T. Houk, Chem. Soc. Rev.
2
009, 38, 1330–1352; b) L. E. Kreno, K. Leong, O. K. Farha, M. Allendorf,
À
suggest that BMOP can not only recognize but also capture F
R. P. Van Duyne, J. T. Hupp, Chem. Rev. 2012, 112, 1105–1125; c) S. Fisch-
er, J. Schmidt, P. Strauch, A. Thomas, Angew. Chem. Int. Ed. 2013, 52,
12174–12178; Angew. Chem. 2013, 125, 12396–12400; d) X. Liu, Y. Xu,
D. Jiang, J. Am. Chem. Soc. 2012, 134, 8738–8741; e) Y. Cui, Y. Yue, G.
Qian, B. Chen, Chem. Rev. 2012, 112, 1126–1162.
8] a) F. M. Hinterholzinger, B. Rühle, S. Wuttke, K. Karaghiosoff, T. Bein, Sci.
Rep. 2013, 3, 2562; b) S. Saha, B. Akhuli, I. Ravikumar, P. S. Lakshminar-
ayanan, P. Ghosh, CrystEngComm 2014, 16, 4796–4804.
ions. This selective recognition and capture or sequestration of
À
F
ions in a p-conjugated porous polymer is unprecedented,
and the detection limits are low in comparison to discrete
[21]
compounds and porous scaffolds. We further tested the ca-
[
[
À
pability of BMOP to indicate the F ions present in Colgate an-
ticavity toothpaste by extracting it with THF/H O. As seen in
2
9] a) R. Dawson, E. Stoeckel, J. R. Holst, D. J. Adams, A. I. Cooper, Energy En-
viron. Sci. 2011, 4, 4239–4245; b) A. I. Cooper, Adv. Mater. 2009, 21,
Figure S28 of the Supporting Information, with incremental ad-
dition of extract solution, clear enhancement of the blue emis-
sion was observed.
1291–1295; c) H. A. Patel, F. Karadas, J. Byun, J. Park, E. Deniz, A. Canlier,
Y. Jung, M. Atilhan, C. T. Yavuz, Adv. Funct. Mater. 2013, 23, 2270–2276;
Chem. Eur. J. 2015, 21, 10799 – 10804
www.chemeurj.org
10803
ꢀ 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Full Paper
d) S. Hug, M. E. Tauchert, S. Li, U. E. Pachmayr, B. V. Lotsch, J. Mater.
Chem. 2012, 22, 13956–13964.
Khimyak, D. J. Adams, A. I. Cooper, Macromolecules 2010, 43, 8524–
8530.
[
[
10] J. X. Jiang, F. Su, A. Trewin, C. D. Wood, N. L. Campberll, H. Niu, C. Dick-
inson, A. Y. Ganin, M. J. Rosseinsky, Y. Z. Khimyak, A. I. Cooper, Angew.
Chem. Int. Ed. 2008, 47, 2458–2462; Angew. Chem. 2008, 120, 2492–
[16] a) J.-X. Jiang, F. Su, A. Trewin, C. D. Wood, H. Niu, J. T. A. Jones, Y. Z. Khi-
myak, A. I. Cooper, J. Am. Chem. Soc. 2008, 130, 7710–7720; b) J.-X.
Jiang, A. Trewin, F. Su, C. D. Wood, H. Niu, J. T. A. Jones, Y. Z. Khimyak,
A. I. Cooper, Macromolecules 2009, 42, 2658–2666.
[17] B. S. Ghanem, M. Hashem, K. D. M. Harris, K. J. Msayib, M. Xu, P. M.
Budd, N. Chaukura, D. Book, S. Tedds, A. Walton, N. B. McKeown, Macro-
molecules 2010, 43, 5287–5294.
[18] a) C. Ronning, D. Schwen, S. Eyhusen, U. Vetter, H. Hofsäss, Surf. Coat.
Technol. 2002, 158, 382–387; b) L. Ci, L. Song, C. Jin, D. Jariwala, D. Wu,
Y. Li, A. Srivastava, Z. F. Wang, K. Storr, L. Balicas, F. Liu, P. M. Ajayan, Nat.
Mater. 2010, 9, 430–435; c) A. F. Lee, Z. Chang, S. F. J. Hackett, A. D.
Newman, K. Wilson, J. Phys. Chem. C 2007, 111, 10455–10460.
[19] a) G. M. Scheuermann, L. Rumi, P. Steurer, W. Bannwarth, R. Muelhaupt,
J. Am. Chem. Soc. 2009, 131, 8262–8270; b) S. Mandal, D. Roy, R. V.
Chaudhari, M. Sastry, Chem. Mater. 2004, 16, 3714–3724; c) L. Lin, T.
Zhang, X. Zhang, H. Liu, K. L. Yeung, J. Qiu, Ind. Eng. Chem. Res. 2014,
53, 10906–10913; d) E. L. Spitler, B. T. Koo, J. L. Novotney, J. W. Colson,
F. J. Uribe-Romo, G. D. Gutierrez, P. Clancy, W. R. Dichtel, J. Am. Chem.
Soc. 2011, 133, 19416–19421.
2
496.
11] a) Z. Chang, D.-S. Zhang, Q. Chen, X. H. Bu, Phys. Chem. Chem. Phys.
013, 15, 5430–5442; b) A. Thomas, Angew. Chem. Int. Ed. 2010, 49,
328–8344; Angew. Chem. 2010, 122, 8506–8523; c) H. A. Patel, S. H. Je,
J. Park, D. P. Chen, Y. Jung, C. T. Yavuz, A. Coskun, Nat. Commun. 2013,
, 1357; d) K. V. Rao, S. Mohapatra, C. Kulkarni, T. K. Maji, S. J. George, J.
2
8
4
Mater. Chem. 2011, 21, 12958–12963; e) K. V. Rao, R. Haldar, T. K. Maji,
S. J. George, Chem. Mater. 2012, 24, 969–971.
[
12] a) V. M. Suresh, S. Bonakala, S. Roy, S. Balasubramanian, T. K. Maji, J.
Phys. Chem. C 2014, 118, 24369–24376; b) K. V. Rao, S. Mohapatra, T. K.
Maji, S. J. George, Chem. Eur. J. 2012, 18, 4505–4509; c) J.-X. Jiang, A.
Trewin, D. J. Adams, A. I. Cooper, Chem. Sci. 2011, 2, 1777–1781; d) L.
Chen, Y. Honsho, S. Seki, D. Jiang, J. Am. Chem. Soc. 2010, 132, 6742–
6
748; e) S. Ren, R. Dawson, D. J. Adams, A. Cooper, Polym. Chem. 2013,
4, 5585–5590.
[
[
[
13] a) G. Cheng, T. Hasell, A. Trewin, D. J. Adams, A. I. Cooper, Angew. Chem.
Int. Ed. 2012, 51, 12727–12731; Angew. Chem. 2012, 124, 12899–12903;
b) J. Brandt, J. Schmidt, A. Thomas, J. D. Epping, J. Weber, Polym. Chem.
[20] a) S. SolØ, F. P. Gabbai, Chem. Commun. 2004, 1284–1285; b) M. Melaimi,
F. P. Gabbai, J. Am. Chem. Soc. 2005, 127, 9680–9681.
[21] a) N. N. Adarsh, A. GrØlard, E. J. Dufourc, P. Dastidar, Cryst. Growth Des.
2012, 12, 3369–3373; b) B. Chen, L. Wang, F. Zapata, G. Qian, E. B. Lob-
kovsky, J. Am. Chem. Soc. 2008, 130, 6718–6719.
2011, 2, 1950–1952.
14] a) N. Matsumi, Y. Chujo, Polym. J. 2007, 40, 77–89; b) W.-M. Wan, F.
Cheng, F. Jäkle, Angew. Chem. Int. Ed. 2014, 53, 1–6; Angew. Chem.
2014, 126, 1–1; c) P. Chen, F. Jäkle, J. Am. Chem. Soc. 2011, 133, 20142–
2
0145; d) F. Jäkle, Chem. Rev. 2010, 110, 3985–4022.
15] a) A. P. Cote, A. I. Benin, N. W. Ockwig, M. O’Keeffe, A. J. Matzger, O. M.
Received: January 31, 2015
Yaghi, Science 2005, 310, 1166–1170; b) R. Dawson, A. Laybourn, Y. Z.
Published online on June 12, 2015
Chem. Eur. J. 2015, 21, 10799 – 10804
www.chemeurj.org
10804
ꢀ 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim