A Review on Calixarene Fluorescent Chemosensor Agents for Various Analytes

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by  K. T. A. Priyangga, Y. S. Kurniawan, K. Ohto, and J. Jumina

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Journal of Multidisciplinary Applied Natural Science Vol. 2 No. 1 (2022) https://doi.org/10.47352/jmans.2774-3047.101
Review Article
A Review on Calixarene Fluorescent Chemosensor Agents for
Various Analytes

Krisfian Tata Aneka Priyangga, Yehezkiel Steven Kurniawan*, Keisuke Ohto, and Jumina Jumina
Received : July 25, 2021 Revised : October 17, 2021 Accepted : November 08, 2021 Online : November 08, 2021
Abstract
Calixarenes are well-known supramolecular host molecules with versatile applications. Over the past decades, hundreds of selective
and sensitive detections have been reported by employing calixarenes as the chemosensor agent. The detection and quantification of
ionic species are crucial as heavy metal ions are harmful to living organisms, while monitoring anions is pivotal in the environmen-
tal samples. On the other hand, detecting and quantifying biomolecules and neutral molecules are critical due to their irreplaceable
role in human health. In this review, we summarized the application of calixarenes as the supramolecular chemosensor agent for
detecting metal ions, anions, biomolecules, and neutral molecules through fluorescent spectroscopy. This review updates the world
with the application of calixarene derivatives as fluorescent chemosensors and challenges researchers to design and develop better
chemosensor agents in the future.
Keywords chemosensor; calixarene; fluorescent; supramolecular

1. INTRODUCTION can be used as a real-time analysis for a selective
detection of analyte [8].
The design and development of sensitive and A chemosensor agent is also known as a
selective chemosensor agents have received molecular sensor or probe. Chemosensor agents can
significant attention from researchers over several be employed in the form of a supramolecular-based
years [1]-[5]. A chemosensor agent is a chemical compound. In this case, the non-covalent interaction
that can provide specific intermolecular interactions between chemosensor and analyte is usually defined
with a particular substrate or analyte, producing a as the host-guest interaction [9]. Chemosensor
detectable signal response. According to the usually contains at least two parts: the binding site
targeted analyte, chemosensor agents can be (receptor) and signaling unit (detector). The
classified into three classes, i.e., cationic, anionic, receptor plays a role as the part for interacting with
and neutral chemosensor agents [6]. Sensing of the analyte to induce signal change. On the other
these analytes by using an optical chemosensor hand, the signaling unit provides a signal response
agent had received special attention due to its change after the interaction with the analyte. The
merits, such as easy sample preparation, quick signaling unit may be composed of the
response rate with high precision, and low-cost chromophore (in colorimetric sensor) or
analysis [7]. Specifically, optical chemosensors are fluorophore (in fluorometric sensor) [10]. The
usually employed by using spectroscopic colorimetric chemosensor agent involves a sensing
techniques such as colorimetric and fluorometric mechanism that leads to a naked eye color change
methods. Compared to the other spectroscopic when interacting with the analyte. Meanwhile, the
techniques, colorimetric and fluorometric methods fluorometric chemosensor agent works through two
offer a simple operation with high sensitivity and mechanisms, i.e., fluorescent-OFF à ON and
fluorescent-ON à OFF (see Figure 1). The design
Copyright Holder:
and development of chemosensor agents with a
© Priyangga, K. T. A., Kurniawan, Y. S., Ohto, K., and
suitable host-guest interaction to the specific
Jumina, J. (2022)
analyte are interesting topics for several decades.
First Publication Right: Furthermore, the topic of chemosensor also
Journal of Multidisciplinary Applied Natural Science
includes the preparation of chemosensor agents

through either organic or inorganic synthesis,
Publisher’s Note:
optical properties, and its analytical application
Pandawa Institute stays neutral with regard to jurisdictional
claims in published maps and institutional affiliations. [11].
Chemosensor agent has been widely applied to
This Article is Licensed Under:
detect and quantify cations, anions, or neutral
molecules in simulated or real sample analysis. As
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Figure 1. The general sensing mechanism of colorimetric and fluorometric chemosensor agents.
an example, detection and quantification of heavy agent. Because of that, a brief review on the
metals are crucial as they are harmful to living application of calixarenes as the fluorescent
organisms. These heavy metals are often found in chemosensor agent is useful to give brief
polluted aquatic samples. Because of that, cation information about the design and development on
sensing gained significant attention to establish a the chemosensor field. However, the latest review
sustainable future [12]. The detection of anions is article on the fluorescent chemosensor based on
also essential due to their important role in calixarene derivatives was published in 2013 [23].
biological and environmental ecosystems. The Furthermore the application of supramolecular
presence of a certain anion in an acceptable amount calixarenes as fluorescent chemosensor was not
can be useful in some applications but not in an discussed in particular in the recent literature. From
excessive concentration [13]. Meanwhile, the that report, an updated review specifically on the
detection of neutral molecules usually involves fluorescent chemosensor based on supramolecular
recognizing biomolecules such as amino acids and calixarene derivatives has not been available yet as
nucleotides [14][15]. for today. To a certain extent, this review provides a
Calixarene derivatives are well-known host brief update on the utilization of supramolecular-
molecules with versatile applications, including based calixarene derivatives as the fluorometric
chemosensor agents [16]-[21]. Calixarenes chemosensor agent for the detection of cations,
consisted of a macrocyclic oligomer framework anions, and neutral molecules. In the present article,
resulted from the condensation reaction between we also summarized the performance of each
formaldehyde and tert-butylphenol [22]. Calixarene chemosensor agent and provided a brief perspective
has a specific ring size that can be controlled by for future research.
using an ion-template synthesis. The control on the
ring size of calixarenes yields calix[4]arene, calix 2. COLORIMETRIC AND FLUOROMETRIC
[5]arene, calix[6]arene, and calix[8]arene [23][24]. DETECTIONS
The conformation of the calixarene can also be
controlled in various conformations such as cone, Colorimetric is the simplest detection method in
partial cone, 1,2-alternate, and 1,3-alternate [25], as the chemosensor field. Colorimetric offers the
shown in Figure 2. Moreover, the calixarenes can naked eye investigation using a visible
be easily modified on their upper or lower rim [26]. spectrophotometer instrument [27]. In the
Calixarenes are reported to have good colorimetric method, a chemosensor should contain
photoluminescence properties; thus, calixarenes a chromophore group as the signaling unit. The
have been extensively used as the chemosensor chromophore is responsible for the color of the
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chemosensor in its free form and the specific color 3. CALIXARENE FOR CATION
change after its interaction with a particular analyte. CHEMOSENSOR
Therefore, the colorimetric method works by
measuring the absorbance change after the addition The usage of calixarenes for the detection of
of the analyte [28]. Because of that, the colorimetric metal ions have been developed in recent years. For
method has a limitation on poor sensitivity and example, Xu and coworkers utilized naphthalimide
background interference. –calix[4]arene (1) for selective detection of Cu2+
In contrast, the fluorometric method is preferable ions in MeCN:H O (9:1 v/v) solvent system.
2
for actual application due to its higher sensitivity Compound 1 gave the quenching phenomenon at
than the colorimetric method. The fluorometric emission wavelength (λ ) of 490 nm (excitation
em
method has been widely used to detect and quantify wavelength, λ = 435 nm) with the presence of
ex
cations, anions, or neutral molecules. The Cu2+. An excellent selectivity was observed over
fluorometric technique uses a chemical with a the other metal ions such as Ag+, Li+, Na+, K+, Rb+,
fluorophore unit, in chemosensor application [29]. Cs+, Ca2+, Cd2+, Co2+, Hg2+, Mg2+, Mn2+, Ni2+, Pb2+,
The fluorometric chemosensor can interact with the and Zn2+, which was remarkable. The oxygen atoms
analyte through several sensing mechanisms such as of calixarene and nitrogen atoms of naphthalimide
intramolecular charge transfer (ICT), photoinduced are responsible for Cu2+ binding, generating a 1:1
electron transfer (PET), chelation-induced enhanced complex with an association constant (K ) of 2.9 ×
a
fluorescence (CHEF), chelation quenched 104 M-1 [36].
fluorescence (CHQF), aggregation caused Wang and coworkers employed a pyrene-
quenching (ACQ), and aggregation-induced modified calix[4]arene (2) for selective detection of
emission (AIE) [30]-[35]. Schematic examples for Na+ cation in DMSO:MeCN (1:9 v/v). When the
each sensing mechanism are depicted in Figure 3. calixarene 2 was excited at 343 nm, its excimer
The different phenomenon leads to a different emission signal at 477 nm was quenched, while the
pathway to detect a certain analyte. However, monomer emission signal at 375 nm was increased
detection using the fluorometric method generally with the presence of Na+. In contrast, the emission
can be classified into two pathways: Fluorescence signal was not significantly changed by the addition
OFF and Fluorescence ON. Fluorescence OFF of the other metal ions such as Li+, K+, Cs+, Mg2+,
happened when the emission intensity of the free Ca2+, Sr2+, and Ba2+. This excellent selectivity was
chemosensor agent was quenched due to the caused by the presence of four carbonyls of ester
addition of a certain analyte. Meanwhile, the functional group encapsulated the Na+ ions in an
Fluorescence ON increases the emission intensity ionophoric cavity. The complexation happened on
due to the interaction between the chemosensor the calixarene 2 lower rim, thus affecting the pyrene
agent and analyte. moieties on the upper rim. Calixarene 2 acted as a
molecular tweezer with an on-off mechanism
controlled with Na+ ions. Initially, the pyrene
moieties overlapped through π-π stacking, thus
Figure 2. The conformational isomers of calixarenes; a) cone, b) partial cone, c) 1,2-alternate, d) 1,3-
alternate.
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Figure 3. Schematic fluorescence sensing mechanisms, i.e., a) ICT, b) PET, c) CHEF and CHQF, d) ACQ,
and e) AIE.
generating an excimer emission signal at 477 nm. In spectroscopic study, the M3+ ions interacted with
contrast, complexation with Na+ ions at the lower benzofurazan rings, amide oxygens, and phenoxy
rim of calixarene 2 forced the pyrenes to stay away oxygen atoms of calixarene 3. The K value of this
a
from each other; thus, the excimer emission signal chelation was 1.0 × 104 M-1 suggesting a moderate
was quenched, but the monomer emission signal strength complexation. The sensitivity of calixarene
was activated. The calixarene 2 formed a 1:1 3 was shown from a low limit detection (LoD)
complex with Na+ ions giving a K value of 2.2 × value (5 µM). The formed complex between
a
103 M-1 [37]. calixarene 3 and M3+ ions was reversible by the
Dinda and coworkers used the addition of H PO −. Therefore, this chemosensor
2 4
nitrobenzoxadiazole appended calix[4]arene agent can be reused for the detection and
derivative (3) for selective recognition of trivalent quantification of these trivalent metal ions.
metal ions, i.e., Cr3+, Fe3+, and Al3+. The detection Furthermore, a real application of calixarene 3 for
of these trivalent metal ions occurred through a the detection of M3+ ions was also established
fluorescence ON as the fluorescence quantum yield within MCF-7 cells [38].
of calixarene 3 was significantly enhanced after the Zhan and coworkers used the anthraquinone-
addition of metal ions. The calixarene 3 had a low calix[4]arene (4) for selective detection of Ca2+
emission intensity at 550 nm (λ = 470 nm); ions. The selective detection of Ca2+ ions was found
ex
however, the addition of M3+ increased its over the other metal ions such as Ag+, Na+, K+, Li+,
fluorescence intensity in a 4-fold increment of Cs+, Mg2+, Sr2+, Ba2+, Cu2+, Cd2+, Ni2+, Mn2+, Co2+,
quantum yield. This phenomenon happened because and Zn2+. The sensing method was performed in
of chelation enhanced fluorescence intensity acetonitrile media, and it was found that the
between calixarene 3 and metal ions. From the interaction between calixarene 4 and Ca2+ ions
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increased the emission intensity at 510 nm (λ = Li and coworkers employed calixarene 5 for the
ex
390 nm). The addition of Ca2+ ions at various detection of Fe3+ and Cu2+ ions in H O:MeOH (1:1
2
concentrations gradually increased its fluorescence v/v) media. The fluorescence intensity of calixarene
intensity yielding a LoD value of 50 µM. The 5 was significantly quenched by the addition of Fe3+
fluorescence ON phenomenon was generated from and Cu2+ ions. Meanwhile, the addition of other
a 1:1 complexation reaction between calixarene 4 metal ions such as Co2+, Ni2+, Zn2+, Mn2+, Mg2+,
and Ca2+ with a K value of 1.2 × 104 M-1. The Ca2+ and Ba2+ did not significantly change the
a
ions bind to the nitrogen atoms of triazole in fluorescence intensity of calixarene 5. The
calixarene 4, leading to a restriction of the PET and calixarene 5 formed a 1:1 complex structure with
an increase in emission intensity [39]. either Fe3+ or Cu2+ ions only at a low concentration
Figure 4. Chemical structures of calixarene-based chemosensor agents 1–10 for cations sensing.
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Table 1. Performance of calixarene-based chemosensor agents for cation sensing.
LoD K
Calixarene Sensing media a Analyte Reference
(nM) (M-1)
1 MeCN:H O (9:1 v/v) n/a 2.9 × 104 Cu2+ [36]
2
2 DMSO:MeCN (1:9 v/v) n/a 2.2 × 103 Na+ [37]
3 n/a 5,000 1.0 × 104 Cr3+, Fe3+, and Al3+ [38]
4 MeCN 50,000 1.2 × 104 Ca2+ [39]
5 H O:MeOH (1:1 v/v) n/a n/a Fe3+ and Cu2+ [40]
2
6 MeCN:CHCl (1000:4 v/v) n/a 1.6 × 104 Cu2+ [41]
3
7 H O:MeCN (1:1 v/v) n/a n/a Hg2+ [42]
2
8 MeOH 0.69 n/a Zn2+ [43]
9 n/a 490 3.7 × 104 La3+ [44]
10 DCM:MeCN (1:1 v/v) 490 n/a Pb2+ [45]
*n/a: not available
(less than 1 µM). At a higher concentration of the over the other heavy metal ions such as Pb2+ and
metal ions lead to the formation of a different Cd2+. Unfortunately, the sensitivity for Hg2+
complex stoichiometry. This phenomenon in detection has not been evaluated yet [42].
fluorescence quenching was also highly related to Joseph and coworkers investigated the
the pH value of the aqueous media [40]. application of calix[4]arene 8 to detect Zn2+ ions.
Chang and coworkers used the modified calix[4] The calixarene 8 showed an excellent sensitivity for
arene with anthracene-isoxazolymethyl group (6) at Zn2+ ions with the LoD value of 0.69 nM in
the lower rim for the detection of Cu2+ ions. The methanol media, which was remarkable. The
calixarene 6 showed two emission peaks at 511 nm emission intensity of calixarene 8 at 380–620 nm
(excimer) and 430 nm (monomer) with the λex of (λ = 370 nm) was significantly increased by the
ex
375 nm. The calixarene 6 showed selectivity and presence of Zn2+ ions. Additionally, calixarene 8
sensitivity in the detection of Cu2+ in also exhibited good selectivity for the detection of
CH CN:CHCl (1000:4, v/v) solvent system, Zn2+ ions. The addition of the other metal ions such
3 3
through coordination with isoxazole moieties. The as Na+, K+, Mn2+, Co2+, Ca2+, Mg2+, and Cd2+ did
selectivity was compared to the 14 metal ions not significantly change the emission intensity of
including Ag+, Li+, Na+, K+, Mg2+, Ca2+, Ba2+, Pb2+, calixarene 8. The addition of these metal ions gave
Hg2+, Cd2+, Ni2+, Mn2+, Zn2+, and Cr3+. The a negligible interference for Zn2+ detection,
fluorescence emission intensity was quenched only indicating a good selectivity. The Fluorescence turn
with the addition of Cu2+ ions, while the other -ON phenomenon happened due to the binding of
cations did not significantly change the Zn2+ to the imine and phenolic moieties of
fluorescence spectra of the free ligand. The calixarene 8 blocking the PET to the salicylyl
calixarene 6 formed complex with Cu2+ with a 1:1 moiety [43].
ratio with a K value of 1.6 × 104 M-1 [41]. Mummidivarapu and coworkers employed a
a
Arena and coworkers utilized calix[4]arene calix[6]arene with triazole linked picolimine
bearing N-(phenyl)sulfonylcarboxamide (7) for conjugate (9) for the detection of La3+ ions.
selective detection of Hg2+ ions in H O:MeCN (1:1 Calixarene 9 showed a selective and sensitive
2
v/v) media. The presence of Hg2+ ions quenched the detection for La3+ ions with a LoD value of 490 nM.
fluorescence intensity of calixarene 7. The sensing The sensing mechanism happened through
mechanism occurred through the Turn-OFF fluorescence turn-ON on the emission intensity of
fluorescence at λ of 312 nm (λ = 273 nm). The 450 nm (λ = 330 nm). The addition of the other
em ex ex
calixarene 7 showed high selectivity for Hg2+ ions trivalent metal ions such as Pr3+, Nd3+, Sm3+, Eu3+,
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Gd3+, Dy3+, and Ho3+ did not significantly increase (ESPT), leading to an increase in the fluorescence
the emission intensity. Calixarene 9 complexed emission [44].
with La3+ ions with a K value of 3.7 × 104 M-1. In Kumar and coworkers applied the pyrene-
a
this case, the imino-phenolic and the pyridyl appended calix[4]arenes derivative (10) for the
moieties play an important role in binding with La3+ fluorometric detection of Pb2+ ions in DCM:MeCN
ions. Complex formation between calixarene 9 and (1:1 v/v) media. Calixarene 10 exhibited excellent
La3+ ions triggered the inhibition of imine sensitivity and selectivity for detecting Pb2+ ions at
isomerization and excited-state proton transfer λ of 498 nm (λ = 350 nm). By addition of Pb2+
em ex
Figure 5. Chemical structures of calixarene-based chemosensor agents 11–19 for anions sensing.
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Table 2. Performance of calixarene-based chemosensor agents for anion sensing.
LoD K
Calixarene Sensing media a Analyte References
(nM) (M-1)
11 THF 100 1.6 x 103 F− [46]
12 MeCN:CH Cl (1:1 v/v) 2,980 5.35 x 108 F− [47]
2 2
13 MeOH 5,000 1.49 x 10-4 I− [48]
14 n/a 4,500 15.6 x 102 I− [49]
15 MeCN:CHCl (99.6:0.4 v/v) n/a n/a F− [50]
3
H PO −, F−, and
16 n/a n.a n/a 2 4 [51]
AcO−
17 MeCN:H O (7:3 v/v) 1,260 n/a CN− [52]
2
18 MeCN:H O (8:2 v/v) 350 n/a S2− [53]
2
19 THF:H O (7:3 v/v) 164 n/a I− [54]
2
*n/a: not available
ions, the excimer emission intensity of calixarene a 1:1 complex structure was formed with a K value
a
10 at 498 nm was gradually quenched, with a of 1.6 × 103 M-1; thus, the λ at 520 nm (λ = 460
em ex
gradual increment of emission signal at 415 nm. nm) was significantly quenched. From the
This hypsochromic shifting was attributed to the experimental-NMR and computational-density
deprotonation of phenolic groups of calixarene 10. functional theory (DFT) studies, it was found that
The addition of other metal ions such as Ag+, Li+, the F− ion was coordinated through extended
Na+, K+, Zn2+, and Hg2+ (in perchlorate salts) gave hydrogen bonds with dibenzooxadiazole and
no significant fluorescence change for calixarene phenoxy oxygen atoms of calixarene 11. These
10. Calixarene 10 gave a LoD value for detecting chelations became the reason for such excellent
Pb2+ as low as 490 nM as calculated from the selectivity of F− ions complexation and sensing.
ratiometric plot of I /I . Calixarene 10 formed a The chemosensor 11 offered good reusability as it
415 498
1:1 complex with Pb2+ ions through the imino can be decomplexed by the addition of Ca2+ ions
group, causing an ICT from pyrene to the imino with still good sensing capability even at 10 cycle
groups [45]. sensing. Furthermore, a biological application for
detecting F− ions in the HeLa cells was also
4. CALIXARENE FOR ANION performed. The results demonstrated that calixarene
CHEMOSENSOR 11 exhibited great application in the THF media as
well as in HeLa cells [46].
Uttam and coworkers employed a calix[4]arene Hosseinzadeh and coworkers used the ferrocene-
conjugated with 1,3-dibenzooxadiazole (11) for the triazole-amide functionalized calix[4]arene (12) for
detection of fluoride anion (F−) in tetrahydrofuran the detection of F− in MeCN:DCM (1:1 v/v) media.
(THF) solvent. Calixarene 11 could selectively Calixarene 12 showed a selective and sensitive
detect F− anion over 15 other anions such as detection of F− anion compared to the other anion
bromide (Br−), chloride (Cl−), iodide (I−), azide including acetate (AcO−), Cl−, Br−, ClO −, NO −,
4 3
(N −), thiocyanate (SCN−), bicarbonate (HCO −), H PO −, and HSO −. The selectivity of calixarene
3 3 2 4 4
dihydrogen phosphate (H PO −), carbonate (CO 2−), 12 was shown from the enhancement in
2 4 3
nitrite (NO −), nitrate (NO −), sulfate (SO 2−), fluorescence emission intensity at 418 nm (λ =
2 3 4 ex
pyrophosphate (P O 4−), perchlorate (ClO −), and 290 nm). In addition, the LoD value for F−
2 7 4
bisulfate (HSO −). Calixarene 11 also exhibited a detection was 2.98 µM. The extended hydrogen
4
sensitive detection of F− with a LoD value of 100 bonds between F− ions and amide and triazole
nM. In the detection of F− ions using calixarene 11, protons of calixarene 12 corresponded to the
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binding site in the sensing mechanism, as revealed The fluorescence response in the detection of both
by the NMR titration study. The calixarene 12 and ions occurred through a quenching phenomenon at
F− ions formed a 1:2 complex structure with a K its emission intensity at λ 360 nm (λ = 330 nm).
a em ex
value of 5.4 × 108. The complexation was formed The LoD value for the detection of Au3+ and I− were
through the hydrogen bond between F− from both 15 and 4.5 µM respectively. The quenching
amide and triazole protons in calixarene 12 [47]. response was due to a 1:1 complexation reaction
Gómez-Machuca and coworkers synthesized a between calixarene 14 and either Au3+ or I− which
calix[4]arenes with azolyl moieties (13) for the gave a K value of 8 × 102 or 16 × 102 M-1,
a
detection of I− anion in MeOH. Calixarene 13 gave respectively. The imine (C=N), amide carbonyl
both sensitive and selective detection of I− (C=O), and hydroxyl functional groups were
compared to the other anions (F−, HSO −, N −, important in the Au3+ sensing. Meanwhile, the
4 3
NO −, NO −, SCN−, ClO −, Br−, CN−, Cl−, CH CO −, hydroxyl and amide nitrogen atoms of calixarene 14
2 3 4 3 2
CF SO −). The tetrabutylammonium salts were used interacted with I− anion through the extended
3 3
to avoid any cationic complexation with calixarene hydrogen bonds [49].
13. In addition, calixarene 13 gave a quenching Miao and coworkers applied a calix[4]arene with
response at λ of 330 nm (λ = 225 nm) by the diaminoanthracene group (15) for the detection of
em ex
addition of I− anion yielding a LoD value of 5 µM. AcO− in MeCN:CHCl (99.6:0.4 v/v). The
3
Calixarene 13 formed a 1:1 complex with I− ion tetrabutylammonium salts were used to avoid any
through hydrogen bonds with a K value of 1.5 × 10 cationic complexation with calixarene 15.
a
-4 M-1. From the NMR titration study, the signal of Calixarene 15 can selectively detect AcO− over the
N-H amide and Ar-H of benzoxazole moieties other anions such as Cl−, Br−, I−, NO −, HSO −, and
3 4
changed clearly. The N-H signal was shifted to a H PO −. The addition of AcO− to calixarene 15
2 4
higher chemical shift due to an extended hydrogen yielded a quenching of emission signal at λ 438
em
bond with I− ions. Meanwhile, the changed Ar-H nm (λ = 370 nm). The quenching happened
ex
benzoxazole signals occurred due to the fixed and through a free PET process between calixarene 15
rigid structure of benzoxazole substituents after I− and AcO− anion. Meanwhile, no spectral changes
complexation reaction [48]. were observed by the addition of other anions.
Memon and coworkers utilized a calix[4]arene Furthermore, the detection of AcO− occurred
bearing naphtyhylimino moiety (14) for sensitive through hydrogen bonds between -NH and 9-H of
and selective detection of Au3+ cation and I− anion. anthracene as confirmed from the 1H-NMR titration
Figure 6. Chemical structures of calixarene-based chemosensor agents on 20–26 for neutral molecules
sensing.
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Table 2. Performance of calixarene-based chemosensor agents for anion sensing.
Calixarene Sensing media LoD (µM) K (M-1) Detection References
a
20 CHCl 3.49–107 n/a Nitroaromatics [56]
3
21 H O n/a 3.5 × 103 – 1.4 × 105 Amino acids [57]
2
Amino
22 MeCN n/a 9.1–56.5 × 101 [58]
alcohols
23 H O 24.5 x 10-3 3.7 × 105 NADH [59]
2
24 n/a 3.81 x 10-3 1.3 × 105 PM [60]
25 MeCN 0.10 1.2 × 105 MC [61]
MeOH:iPrOH
26 2.25 n/a glyphosate [62]
(1:1 v/v)
*n/a: not available
study [50]. LoD value as low as 0.4 μM. Interestingly, the
Hung and coworkers prepared a calix[4]arene addition of Cu2+ followed by CN− ion leads to a
owing to pyrenylacetamide functional group (16) gradual increment of emission signal at 405 nm. It
for the detection of H PO −, F−, and AcO− anions. means that the calixarene 17 could also be used for
2 4
Three different binding modes were observed for the detection of CN− through the formation of Cu2+-
these anions. Static excimer with large and small calixarene 17 complex. The LoD value for CN−
charge transfer occurred for F− and AcO− anions, detection was 1.26 μM. Furthermore, a selective
respectively. Meanwhile, an increment in monomer detection for CN− was achieved over F−, Cl−, Br−,
emission of calixarene 16 happened for H PO − I−, S2−, AcO−, CO 2−, HSO −, and H PO −. The CN−
2 4 3 4 2 4
sensing. The dynamic excimer emission of detection was stable in a pH region of 6–8. Lower
calixarene 16 (λ = 482 nm) was quenched by the pH value protonated quinoline nitrogen atoms while
em
addition of F− at a low concentration. However, in higher pH value formed a hydroxide complex of
an excess concentration of F−, the emission signal at [Cu(OH) ](2-m)+. The selectivity of Cu2+-calixarene
m
472 nm was increased significantly. This 17 complex for CN− detection happened as the Cu2+
phenomenon was caused by the formation of a ion itself was able to form a very stable metal
strong extended hydrogen bond between F− and complex with CN− anion. Additionally, the
calixarene 16 through its amide group, leading to a chelation of calixarene 17 aided in locking the CN−
generation of pyrene dimers. On the other hand, anion through extended hydrogen bonds with
H PO − sensing showed an opposite mechanism as quinoline and amide nitrogen atoms, thus providing
2 4
the monomer emission at 472 nm was enhanced, an excellent sensing site for CN− anion [52]. These
but the excimer emission at 482 nm was decreased results are useful for developing a dual-response
[51]. chemosensor agent for the detection of cation and
Chawla and coworkers investigated the anion with high selectivity and sensitivity.
application of calix[4]arene bearing quinoline Ramachandran and coworkers designed calix[4]
moiety (17) for the detection of Cu2+ and CN− ions arene 18 for the detection of Cu2+ and S2− ion in
in MeCN:H O (7:3 v/v) media. Calixarene 17 could MeCN:H O (8:2 v/v) media. Free calixarene 18
2 2
selectively detect Cu2+ over the other metal ions showed a photoluminescence property at λ of 637
em
such as Zn2+, Pb2+, Co2+, Ni2+, Na+, Li+, Fe3+, Hg2+, nm (λ = 457 nm). The addition of Cu2+ led to a
ex
Cd2+, K+, Mn2+, and Ag+. The addition of Cu2+ leads gradual quenching by increasing Cu2+
to a significant quenching at λ of 405 nm (λ = concentration. The LoD value of Cu2+ was 4.11 μM,
em ex
315 nm) of calixarene 17. The sensitivity of with a K value of 2.3 × 104 M-1. Calixarene 18
a
calixarene 17 for Cu2+ detection was shown by its showed a high selectivity for Cu2+ detection
32