New highly selective colorimetric and fluorescent chemodosimeters for mercury ion

Article abstract of DOI:10.1071/CH09431

Three new chemodosimeters 1-3 were prepared, and their chromogenic and fluorogenic behaviours toward various metal cations were investigated. Receptors 1-3 show an exclusive response toward Hg²⁺ and also distinguish Hg²⁺ from other metal cations by different colour changes in aqueous DMSO solution. Among them, receptor 1 also exhibits a pronounced Hg ²⁺-induced fluorescence enhancement. Therefore, the receptor 1 can be used as a colorimetric and fluorescent chemodosimeter for the determination of Hg²⁺ion. CSIRO 2010.

Full text of DOI:10.1071/CH09431

Full Paper
CSIRO PUBLISHING
www.publish.csiro.au/journals/ajc
Aust. J. Chem. 2010, 63, 329–335
New Highly Selective Colorimetric and Fluorescent
Chemodosimeters for Mercury Ion
Chen-Yu Wu,A Chiung-Cheng Lin,A Tung-Ming Fu,A Chi-Rei Yang,B
and Yao-Pin YenA,C
ADepartment of Applied Chemistry, Providence University, Taiwan.
BDivision of Urology, Department of Surgery, Taichung Veterans General Hospital, Taiwan.
CCorresponding author. Email: ypyen@pu.edu.tw
Three new chemodosimeters 1–3 were prepared, and their chromogenic and fluorogenic behaviours toward various metal
cations were investigated. Receptors 1–3 show an exclusive response toward Hg2+ and also distinguish Hg2+ from
other metal cations by different colour changes in aqueous DMSO solution. Among them, receptor 1 also exhibits a pro-
nounced Hg2+-induced fluorescence enhancement. Therefore, the receptor 1 can be used as a colorimetric and fluorescent
chemodosimeter for the determination of Hg2+ ion.
Manuscript received: 10 August 2009.
Manuscript accepted: 17 September 2009.
Introduction
syntheses of three chemodosimeters (1–3) and the photochemi-
cal elucidation of their selective colour and fluorescence changes
toward Hg2+ cation. To the best of our knowledge, 1 is a rare
example of thiourea-based chemodosimeter for Hg2+ ion.
The development of selective chemosensors for the determina-
tion of transition and heavy metal ions has received considerable
attention because they play important roles in living systems and
have an extremely toxic impact on the environment.[1] Among
them, Hg2+ is considered as one of the most dangerous cations to
the environment because it is widely distributed in air, water, and
soil. Mercury can accumulate in the human body and causes a
wide variety of diseases even in a low concentration, such as pre-
natal brain damage, serious cognitive and motion disorders, and
Minamata disease.[2] Therefore, it is highly desirable to develop
selective and sensitive assays for Hg2+ ions.
In recent years, many efforts have been devoted to design
various chemosensors specific for Hg2+ ion detection.[3–8] The
most attractive approach focuses on the research of novel col-
orimetric and fluorescent Hg2+ ion sensors, which allow visual
detection of the change of colour without use of any expen-
sive instruments and fluorescent emission upon specific Hg2+
ion inducing reactions, respectively. Some selective chemodosi-
meters for the Hg2+ ion have been designed to adopt mercury-
promoted desulfurization, leading to an irreversible chemical
event between thioamide derivatives and Hg2+ ion.[4–8] How-
ever, most chemodosimeters developed so far have been known
to be related only to their fluorescence changes upon metal ion
introduction.[8] As we know, chemodosimeters inducing both
colour and fluorescence changes are still rather rare.[8d,9]
In this context, we have designed pyrene-component con-
taining chemodosimeters responsible for Hg2+ ion-induced
desulfurization leading to irreversible, unique colour changes
and fluorescence enhancements. The pyrene subunit is versa-
tile and frequently employed for the construction of important
chemosensors having efficient fluorogenic behaviour.[10] The
phenylthiourea group is remarkably responsive to an electronic
effect of substrate species in the event of the Hg2+ ion-induced
chemodosimetric desulfurization. In this paper, we report the
Results and Discussion
Receptors 1–3 were synthesized by the reaction of
4-trifluoromethylphenyl isothiocyanate, 4-nitrophenyl isothio-
cyanate, or4-methoxyphenylisothiocyanatewith1-aminopyrene
in high yields (Scheme 1). To ensure that the mercury-induced
desulfurization occurred in this event, 4 (90% yield), 5 (90%
yield), and 6 (91% yield) were isolated from the reaction of
1, 2, and 3, respectively, with 1 equiv. of Hg(NO3)2·H2O in
CHCl3/CH3CN at room temperature. Moreover, the authentic
H
H
N
R
N
SCN
R
S
1 R ꢀ CF3
2 R ꢀ NO2
3 R ꢀ OMe
(i)
NH2
(ii)
H
H
N
R
OCN
R
N
O
(iii)
4 R ꢀ CF3
5 R ꢀ NO2
6 R ꢀ OMe
Scheme 1. Reagents and conditions: (i) CHCl3/CH3CN, reflux, 72–84 h;
(ii) Hg(NO3)2·H2O, CHCl3/CH3CN, rt, 0.5 h; and (iii) CHCl3/CH3CN,
reflux, 24–72 h.
© CSIRO 2010
10.1071/CH09431
0004-9425/10/020329

330
C.-Y. Wu et al.
(a)
1
0.8
0.6
0.4
0.2
0
60 ꢁM
(b)
0.8
0.7
0.6
0.5
0.4
0
0
0.5
1
1.5
250
300
350
400
450
[Hg2ꢂ] equiv.
Wavelength [nm]
Fig. 1. Family of spectra taken in the course of the titration of 1 (30 µM, DMSO/H2O, 4:1) with a standard solution of Hg2+ at 25◦C. The
titration profile (insert) indicate the formation of a 1:1 complex.
(a)
1.2
1 ꢂ Agꢂ
1
0.8
1 ꢂ Hg2ꢂ
1, 1 ꢂ X
0.6
0.4
1 ꢂ Cu2ꢂ
0.2
0
250
300
350
400
450
Wavelength [nm]
(b)
Host
Naꢂ Kꢂ Mg2ꢂ Ca2ꢂ Cr3ꢂ Mn2ꢂ Fe3ꢂ Co2ꢂ Ni2ꢂ Cu2ꢂ Agꢂ Pb2ꢂ Zn2ꢂ Cd2ꢂ Hg2ꢂ
Fig. 2. (a) UV-vis spectra of 1 (3.0 × 10−5 M) in the presence of the Hg2+ ion and miscellaneous cations (X) including Na+, K+,
Mg2+, Ca2+, Cr3+, Mn2+, Fe3+, Co2+, Ni2+, Cu2+, Ag+, Pb2+, Zn2+, Cd2+, and Hg2+. (b) Colour changes of 1 (5.0 × 10−4 M)
upon addition of NO−3 salts of X in aqueous solution (DMSO/H2O, 4:1).
compounds 4–6 were also prepared by reaction of the cor-
responding 4-trifluoromethylphenyl isocyanate, 4-nitrophenyl
isocyanate, or 4-methoxyphenyl isocyanate with 1-aminopyrene
in good yields. All of these compounds were characterized by
1H NMR, 13C NMR, and IR spectroscopy and HRMS.
Receptor 1 was soluble in a mixed solvent of DMSO and
H2O (4:1). The pale yellow solution of 1 is found to be sta-
ble within a pH range of 4–10. In the UV-vis titration of the
Hg2+ ions, the receptor 1 exhibited characteristic absorption
peaks at 280, 334, and 350 nm.[10a] Upon treatment with Hg2+
ions, the absorption peaks initially at 280, 334, and 350 nm were
gradually decreased and red-shifted to 286 and 360 nm with
two isosbestic points at 282 and 355 nm, respectively (Fig. 1a).
The colour of the solution changed from pale yellow to sienna
(Fig. 2b). The signalling was completed within 2 min. By plot-
ting the changes of 1 in the absorbance intensity at 360 nm as a
function of Hg2+ concentration, a sigmoidal curve was obtained
and indicated a 1:1 stoichiometry between 1 and Hg2+ ions
(Fig. 1b).
An important feature of the chemodosimeter is its high
selectivity towards the analyte over other competitive species.
Variations of UV-vis spectral and visual colour changes of 1
in aqueous solutions caused by miscellaneous cations including
Na+, K+, Mg2+, Ca2+, Cr3+, Mn2+, Fe3+, Co2+, Ni2+, Cu2+
,
Ag+, Pb2+, Zn2+, Cd2+, and Hg2+ were recorded (Fig. 2). It
is evident that the miscellaneous competitive cations did not
lead to any significant spectral change, except Cu2+ and Ag+
ions, which induced some variation in absorbance without sig-
nificantly changing the absorption maxima. In addition, in the
presence of miscellaneous competitive cations, the Hg2+ ions
still resulted in the similar absorption changes (see Accessory
Publication, SI-1).

Highly Selective Colorimetric and Fluorescent Chemodosimeters for Mercury Ion
331
(a)
1 ꢂ Hg2ꢂ
4000
1 ꢂ X ꢂ Hg2ꢂ
3000
2000
1
1000
1 ꢂ X
0
400
450
500
550
600
Wavelength [nm]
(b)
Host Naꢂ Kꢂ Mg2ꢂ Ca2ꢂ Cr3ꢂ Mn2ꢂ Fe3ꢂ Co2ꢂ Ni2ꢂ Cu2ꢂ Agꢂ Pb2ꢂ Zn2ꢂ Cd2ꢂ Hg2ꢂ
Fig. 3. (a) Fluorescence spectra of 1 in response to the metal ions. [1] = 0.5 µM, [Mn+] = 5.0 µM, in DMSO/H2O, 4:1.
λex = 350 nm. (b) Photographs of 1 (0.5 µM) upon addition of miscellaneous cations (X) including Na+, K+, Mg2+
,
Ca2+, Cr3+, Mn2+, Fe3+, Co2+, Ni2+, Cu2+, Ag+, Pb2+, Zn2+, Cd2+, and Hg2+ (1.0 equiv.) in aqueous solution
(DMSO/H2O, 4:1).
The fluorogenic behaviour of 1 was investigated under the
same conditions. Upon addition of the Hg2+ ion, the initial
weak emission peak at 440 nm was gradually decreased while
the peaks at 395 and 414 nm evolved (Fig. 3a). The fluorescence
enhancement induced by the addition of Hg2+ ions was observed
and the signalling was complete within 1 min. Upon interaction
isocyanate (Scheme 1). On comparing the 13C NMR data of 1
and 4, we found that the resonance evident at 182 ppm for 1 was
replaced by a signal at 153 ppm for 4, indicating that a C=O
group was present in 4 and the C=S group of 1 vanished during
the desulfurization process from 1 to 4 (Fig. SI-3).
Colorimetric and fluorescent detection limits of 1 for
Hg2+ ions were also tested (Fig. 4). In the solvent system
of DMSO/H2O (4:1), the detection limit within visual colour
changes is allowable to 50 µM of Hg2+ ions in a 50 µM solution
of 1, as presented in Fig. 4a. The detection limit of the fluores-
cence changes calculated on the basis of 3σ/K[12] is 0.019 µM
or 3.8 ppb, pointing to the high detection sensitivity (Fig. 4b).
To investigate how the different substituents on the phenyl
ring of the thiourea group can influence the Hg2+ ion sens-
ing properties, the 4-trifluoromethylphenyl group was replaced
by either a more electron withdrawing group, 4-nitrophenyl
group or an electron donating 4-methoxyphenyl group; the
receptors 2 and 3, respectively, were examined. In fact, 2 and
3 show similar photochemical changes to 1 upon Hg2+ ion
introduction. The titration profiles indicate 1:1 stoichiometry
between 2 or 3 and Hg2+ ions (Figs SI-4 and SI-5). The
visual colour changes from light yellow to deep sienna in the
presence of Hg2+ ions are also shown in Figs 5b and 6b, respec-
tively. The distinct colour changes of 2 and 3 were similarly
caused by the Hg2+ induced desulfurzation of the thiourea
function into an urea group. It was also found that the sig-
nalling of receptors 2 and 3 were completed in 2 and 36 min,
respectively. The late signalling of 3 is due to the electron
donating ability of the 4-methoxyphenyl group, which results in
retarding the desulfurization of 3 to alternatively form the corre-
sponding 1-pyrenyl-3-phenylcarbodiimide.[13] The competitive
with various metal ions (Na+, K+, Mg2+, Ca2+, Cr3+, Mn2+
,
Fe3+, Co2+, Ni2+, Cu2+, Ag+, Pb2+, Zn2+, Cd2+, and Hg2+),
only Hg2+ ions induced a sizable enhancement in fluorescence
intensity (76-fold) and fluorescence changes from dark blue
to blue-pink are shown in Fig. 3b. Other metal ions revealed
almost insignificant responses. Moreover, in the presence of mis-
cellaneous competitive cations, the Hg2+ ions still resulted in
the similar fluorescence changes (Fig. SI-2). The increases of
absorbance and fluorescence intensity resulting from the addi-
tion of the Hg2+ ions were not influenced by the subsequent
addition of miscellaneous cations. All this indicates that the
selectivity of 1 for the Hg2+ ions over other competitive cations
in the aqueous medium is remarkably high.
The distinct colour change and large fluorescence enhance-
ment of 1 was caused by the Hg2+ induced transformation of the
thiourea function into a urea group as depicted in Scheme 1. The
hydrolytic conversion of thioureas into ureas catalyzed by certain
metal ions has been known to be very efficient.[11] In the present
case, the conversion was effective, occurring exclusively with
Hg2+ ions in aqueous DMSO. This behaviour is quite reminis-
cent of Czarnik’s Hg2+-selective chemodosimeter that is based
onthethioamidederivativeofanthracene.[5] Furtherevidencefor
theaboveprocesscamefromtheindependentsynthesisof 4from
the direct reaction of 1 and Hg(NO3)2 or alternatively from the
direct reaction of 1-aminopyrene with 4-trifluoromethylphenyl

332
C.-Y. Wu et al.
1 ꢂ Hg2ꢂ
(a)
1
5.0 ꢄ 10ꢃ4 M
1.0 ꢄ 10ꢃ4 M
5.0 ꢄ 10ꢃ5 M
(b)
5000
4000
3000
2000
1000
0
y ꢀ 8E ꢂ 08x ꢂ 382.69
R2 ꢀ 0.9905
0.00Eꢂ00
1.00Eꢃ06
2.00Eꢃ06
3.00Eꢃ06
4.00Eꢃ06
5.00Eꢃ06
[Hg2ꢂ] [M]
Fig. 4. (a) Photograph of 1 in aqueous solution (DMSO/H2O, 4:1) in the presence of the Hg2+ ions. (b) Fluorescence
intensity of 1 versus Hg2+ concentrations. [1] = 0.5 µM.
2 ꢂ Hg2ꢂ
2 ꢂ Agꢂ
(a)
1.4
2 ꢂ Cu2ꢂ
1.2
2, 2 ꢂ X
1
0.8
0.6
0.4
0.2
0
250
300
350
400
450
500
550
Wavelength [nm]
(b)
Host Naꢂ Kꢂ Mg2ꢂ Ca2ꢂ Cr3ꢂ Mn2ꢂ Fe3ꢂ Co2ꢂ Ni2ꢂ Cu2ꢂ Agꢂ Pb2ꢂ Zn2ꢂ Cd2ꢂ Hg2ꢂ
Fig. 5. (a) UV-vis spectra of 2 (3.0 × 10−5 M) in the presence of the Hg2+ ion and miscellaneous cations (X) including
Na+, K+, Mg2+, Ca2+, Cr3+, Mn2+, Fe3+, Co2+, Ni2+, Cu2+, Ag+, Pb2+, Zn2+, Cd2+, and Hg2+. (b) Colour changes of 2
(5.0 × 10−4 M) upon addition of NO3− salts of X in aqueous solution (DMSO/H2O, 4:1).
chemodosimetric reactions in colour changes were carried out
or 3 toward Hg2+ ions is not compromised, even in the presence
of other various cations. It is interesting that Cu2+ and Pb2+
ions can interfere with Hg2+ ion selectivity to cause a serious
problem as reported in other cases.[14] As shown in above data
(Figs SI-6 and SI-7), the chemodosimeters 2 and 3 in this report
using 30 µM of receptor 2 or 3 in the presence of miscellaneous
cations such as Na+, K+, Mg2+, Ca2+, Cr3+, Mn2+, Fe3+, Co2+
,
Ni2+, Cu2+, Ag+, Pb2+, Zn2+, Cd2+, and Hg2+. The results are
indicated in Figs SI-6 and SI-7, respectively. The selectivity of 2

Highly Selective Colorimetric and Fluorescent Chemodosimeters for Mercury Ion
333
(a)
1.4
3 ꢂ Hg2ꢂ
1.2
1
3, 3 ꢂ Agꢂ, 3 ꢂ X
3 ꢂ Cu2ꢂ
0.8
0.6
0.4
0.2
0
250
300
350
400
450
500
550
Wavelength [nm]
(b)
Host
Naꢂ Kꢂ Mg2ꢂ Ca2ꢂ Cr3ꢂ Mn2ꢂ Fe3ꢂ Co2ꢂ Ni2ꢂ Cu2ꢂ Agꢂ Pb2ꢂ Zn2ꢂ Cd2ꢂ Hg2ꢂ
Fig. 6. (a) UV-vis spectra of 3 (3.0 × 10−5 M) in the presence of the Hg2+ ion and miscellaneous cations (X) including Na+, K+,
Mg2+, Ca2+, Cr3+, Mn2+, Fe3+, Co2+, Ni2+, Cu2+, Ag+, Pb2+, Zn2+, Cd2+, and Hg2+. (b) Colour changes of 3 (5.0 × 10−4 M)
upon addition of NO−3 salts of X in aqueous solution (DMSO/H2O, 4:1).
still show a remarkable selectivity toward Hg2+ ions in a solution
Table 1. Summarized fluorescence properties
containing Cu2+ and Pb2+ ions.
Properties of 1, 2, and 3 for Hg(ii) ions, such as excitation wavelength
(λex), extinction coefficient (ε), emission wavelength (λem), and quantum
yield (Φ)[15]
However, 2 and 3 show different fluorescence spectral
changes to 1 upon Hg2+ ion addition. Receptor 2 revealed an
increasing emission band at 440 nm and induced a less clear fluo-
rescence colour change from dark blue to bright blue (Fig. SI-8).
In contrast, the emission band of 3 was blue-shifted from 442 nm
to 404 nm upon treatment with Hg2+ ions and resulted in no
fluorescence colour change (Fig. SI-9). These apparent fluores-
cence enhancements are, however, not as significant as for that
of receptor 1.
Compd
λex [nm]/nm(log ε)
λem [nm]
Φ
1
2
3
350(4.42)
372(4.52)
349(4.49)
350(4.40)
372(4.61)
349(4.52)
440
440
442
395, 414
440
0.045
0.055
0.160
0.279
0.067
0.143
1·Hg(ii)
2·Hg(ii)
3·Hg(ii)
The fluorescence features of 1, 2, and 3 for Hg2+ ions,
respectively, are summarized in Table 1. Regarding the Hg2+
detection by fluorescence, 1 seems to be the best among these
three receptors.
404
obtained using a Bruker spectrometer at 400 (1H) and 100 MHz
(13C) with DMSO-d6 as solvent. High-resolution mass spec-
tra were measured with a Finnigan/Thermo Quest MAT 95XL
instrument.
Conclusion
In conclusion, three novel chemodosimeters were developed
by using an irreversible desulfurization reaction. Receptors
1–3 show high selectivity toward Hg2+ ions over miscella-
neous competitive cations and also distinguish Hg2+ from other
cations by colour changes.Among them, receptor 1 also exhibits
a pronounced Hg2+ ion-induced fluorescence enhancement.
Therefore, the receptor 1 can be used as a colorimetric and
fluorescent chemodosimeter for the determination of Hg2+ ions.
Materials
Ethanol, CH3CN, and CHCl3 were dried and distilled before
use according to the standard procedure. All other commercially
available reagents were used without further purification. The
nitrate salts were used as cationic substrates.
Synthesis
Experimental
1-(4-(Trifluoromethyl)phenyl)-3-(pyren-1-yl)thiourea 1
General Methods
Under nitrogen, to a stirred solution of 1-aminopyrene
(0.217 g, 1.0 mmol) in CHCl3/CH3CN (3:1) was slowly added
4-trifluoromethylphenyl isothiocyanate (0.203 g, 1.0 mmol) in
CHCl3 (10 mL). The resulting mixture was stirred and heated to
reflux for 84 h. After cooling, the solution was filtered. The pre-
cipitate was purified by recrystallization from ethanol to give the
product 1 as a light-khaki solid. Yield: 0.331 g (80%), mp. 168–
169◦C. νmax (KBr)/cm−1 3299, 3199, 3024, 2099, 1588, 1531,
1509, 1492, 1351, 1312, 1291, 1226. λmax (DMSO/H2O, 4:1)/nm
(ε/M−1 cm−1) 350 (30121). δH (d6-DMSO) 10.59 (1H, s), 10.20
The chemical reagents were purchased from Acros or Aldrich
chemical companies and used as received, unless indicated
otherwise. All solvents were purified by standard proce-
dures. Melting points were measured on a Yanaco MP-S3
melting-point apparatus. The infrared spectra were performed
on a Perkin–Elmer System 2000 FT-IR spectrophotometer.
UV-Vis spectra were measured on a Cary 300 UV-visible
spectrometer. Fluorescence spectra were recorded on HITACHI
F-4500 fluorescence spectrophotometer. All NMR spectra were

334
C.-Y. Wu et al.
(1H, s), 8.31–8.05 (9H, m), 7.86 (2H, d, J 8.0), 7.69 (2H, d, J 8.4).
δC (d6-DMSO) 181.9, 144.0, 133.1, 130.9, 130.0, 128.1, 127.7,
127.6, 127.1, 127.0, 126.7, 126.2, 126.0, 125.9, 125.0, 124.8,
124.4, 124.3, 123.9, 123.5, 123.0. m/z (HR-MS FAB) 420.0904;
[M+] requires 420.0909.
1-(4-Methoxyphenyl)-3-(pyren-1-yl)urea 6
The preparation of 6 followed the above mentioned proce-
dure using 4-methoxyphenyl isocyanate and 1-aminopyrene in
the same molar ratio and refluxed for 72 h.Yield: 0.218 g (61%),
green-yellow solid, mp. 275–276◦C. νmax (KBr)/cm−1 3272,
3040, 2360, 1630, 1596, 1563, 1509, 1295, 1240, 839, 709.
λmax (DMSO/H2O, 4:1)/nm (ε/M−1 cm−1) 360 (37782). δH (d6-
DMSO) 9.12 (1H, s), 8.97 (1H, s), 8.61 (2H, d, J 8.4), 8.42–8.02
(9H, m), 7.45 (2H, d, J 8.8), 6.91 (2H, d, J 8.8), 3.71 (3H, s).
δC (d6-DMSO) 155.0, 153.6, 133.8, 133.2, 131.6, 131.1, 127.8,
127.3, 126.8, 126.0, 125.8, 125.4, 125.0, 124.9, 124.7, 121.5,
121.3, 120.4, 120.2, 114.6, 55.6. m/z (HR-MS FAB) 366.1377;
[M+] requires 366.1369.
1-(4-Nitrophenyl)-3-(pyren-1-yl)thiourea 2
The preparation of 2 followed the above mentioned pro-
cedure using 4-nitrophenyl isothiocyanate and 1-aminopyrene
in the same molar ratio and refluxed for 72 h. Yield: 0.351 g
(90%), green-yellow solid, mp. 215–216◦C. νmax (KBr)/cm−1
3292, 3174, 3007, 2359, 1593, 1535, 1513, 1342, 1258, 1232,
848, 819, 743. λmax (DMSO/H2O, 4:1)/nm (ε/M−1 cm−1) 350
(28143), 372 (25792). δH (d6-DMSO) 10.69 (1H, s), 10.50
(1H, s), 8.32–8.20 (9H, m), 8.09 (2H, d, J 7.6), 7.95 (2H, d,
J 8.8). δC (d6-DMSO) 181.7, 146.9, 142.9, 132.9, 131.1, 130.9,
130.1, 128.2, 127.8, 127.6, 127.1, 127.0, 126.0, 125.8, 125.5,
125.0, 124.7, 124.3, 123.0, 122.5. m/z (HR-MS FAB) 398.0966;
[M + H+] requires 398.0965.
Isolation of 1-(4-(Trifluoromethyl)phenyl)-
3-(pyren-1-yl)urea 4
To a stirred solution of 1-(4-(trifluoromethyl)phenyl)-3-(pyren-
1-yl)thiourea (1) (0.042 g, 0.1 mmol) in CHCl3/CH3CN (3:1),
was slowly added Hg(NO3)2·H2O (0.103 g, 0.3 mmol) in CHCl3
(10 mL). The resulting mixture was stirred at room temperature
for 30 min and then washed with saturated Na2S solution and
water, dried over MgSO4, and the solvent evaporated under vac-
uum. The residue was purified by column chromatography on
SiO2 using CHCl3/CH3CN/hexane (2:1:1) as the eluent, to give
0.034 g (90% yield) of 4 as a greyish-white solid, mp. 295–
296◦C. δH (d6-DMSO) 9.54 (1H, s), 9.30 (1H, s), 8.57 (1H, d, J
8.4), 8.34 (1H, d, J 9.6), 8.29–8.25 (4H, m), 8.12–8.06 (3H,
m), 7.76 (2H, d, J 8.8), 7.68 (2H, d, J 8.8). δC (d6-DMSO)
153.3, 144.0, 133.0, 131.5, 127.6, 127.4, 126.9, 126.7, 126.6,
126.4, 125.8, 125.6, 125.1, 124.9, 124.6, 123.7, 122.5, 122.2,
122.1, 121.0, 118.4. m/z (HR-MS FAB) 404.1147; [M+] requires
1-(4-Methoxyphenyl)-3-(pyren-1-yl)thiourea 3
The preparation of 3 followed the above mentioned procedure
using4-methoxyphenylisothiocyanateand1-aminopyreneinthe
same molar ratio and refluxed for 72 h. Yield: 0.192 g (49%),
sea green solid, mp. 172–173◦C. νmax (KBr)/cm−1 3293, 3120,
2399, 2282, 1726, 1599, 1529, 1336, 1270, 1239, 1180, 845, 715.
λmax (DMSO/H2O, 4:1)/nm (ε/M−1 cm−1) 349 (26312). δH (d6-
DMSO) 10.09 (1H, s), 9.64 (1H, s), 8.32–8.05 (9, m), 7.38 (2H,
d, J 9.2), 6.91 (2H, d, J 8.8), 3.73 (3, s). δC (d6-DMSO) 182.0,
157.1, 133.5, 132.8, 131.1, 130.9, 129.8, 127.9, 127.7, 127.5,
127.2, 127.0, 126.9, 125.8, 125.6, 125.4, 125.0, 124.3, 123.2,
114.0, 55.7. m/z (HR-MS FAB) 383.1217; [M + H+] requires
383.1219.
1
404.1137. The H NMR, 13C NMR, and HRMS spectra were
consistent with the above mentioned data.
Isolation of 1-(4-Nitrophenyl)-3-(pyren-1-yl)urea 5
1-(4-(Trifluoromethyl)phenyl)-3-(pyren-1-yl)urea 4
A similar procedure to isolate 5 was carried out using 1-(4-
nitrophenyl)-3-(pyren-1-yl)thiourea (2) and Hg(NO3)2·H2O in
the same molar ratio. Yield: 0.034 g (90%), green-yellow solid,
mp. 258–260◦C. δH (d6-DMSO) 9.84 (1H, s), 9.39 (1H, s),
8.54 (2H, d, J 8.4), 8.32–8.05 (9H, m), 7.79 (2H, d, J 8.8).
δC (d6-DMSO) 153.1, 146.9, 141.5, 132.6, 131.2, 131.0, 127.8,
127.7, 127.0, 126.6, 125.7, 125.2, 124.9, 124.5, 122.4, 121.6,
121.2, 118.4, 118.0. m/z (HR-MS FAB) 381.1122; [M+] requires
The preparation of 4 followed the above mentioned procedure
using 4-trifluoromethylphenyl isocyanate and 1-aminopyrene
in the same molar ratio and refluxed for 48 h. Yield: 0.332 g
(83%), greyish white solid, mp. 295–296◦C. νmax (KBr)/cm−1
3289, 3139, 3021, 2399, 1628, 1551, 1509, 1452, 1355, 1333,
1291, 1226. λmax (DMSO/H2O, 4:1)/nm (ε/M−1 cm−1) 360
(38119). δH (d6-DMSO) 9.54 (1H, s), 9.30 (1H, s), 8.57 (1H,
d, J 8.4), 8.34 (1H, d, J 9.6), 8.29–8.25 (4H, m), 8.12–8.06
(3H, m), 7.76 (2H, d, J 8.8), 7.68 (2H, d, J 8.8). δC (d6-DMSO)
153.3, 144.0, 133.0, 131.5, 131.0, 127.8, 127.6, 127.4, 126.9,
126.7, 126.4, 125.8, 125.6, 125.1, 125.0, 124.6, 123.7, 122.5,
122.2, 122.1, 121.6, 120.9, 118.4. m/z (HR-MS FAB) 404.1144;
[M+] requires 404.1137.
1
381.1114. The H NMR, 13C NMR, and HRMS spectra were
consistent with the above mentioned data.
Isolation of 1-(4-Methoxyphenyl)-3-(pyren-1-yl)urea 6
A similar procedure to isolate 6 was carried out using 1-(4-
methoxyphenyl)-3-(pyren-1-yl)thiourea (3) and Hg(NO3)2·H2O
in the same molar ratio.Yield: 0.031 g (91%), green-yellow solid,
mp. 275–276◦C. δH (d6-DMSO) 9.12 (1H, s), 8.97 (1H, s), 8.61
(2H, d, J 8.4), 8.42–8.02 (9H, m), 7.45 (2H, d, J 8.8), 6.91 (2H, d,
J 8.8), 3.71 (3H, s). δC (d6-DMSO) 155.0, 153.7, 133.7, 133.2,
131.6, 131.0, 127.8, 127.4, 126.9, 126.8, 126.0, 125.8, 125.4,
125.0, 124.9, 124.7, 121.5, 121.4, 120.5, 120.4, 114.6. 55.6.
m/z (HR-MS FAB) 366.1374; [M+] requires 366.1369. The 1H
NMR, 13C NMR, and HRMS spectra were consistent with the
above mentioned data.
1-(4-Nitrophenyl)-3-(pyren-1-yl)urea 5
The preparation of 5 followed the above mentioned procedure
using 4-nitrophenyl isocyanate and 1-aminopyrene in the same
molar ratio and refluxed for 72 h. Yield: 0.259 g (68%), green-
yellow solid, mp. 259–260◦C. νmax (KBr)/cm−1 3289, 3006,
2451, 2282, 1644, 1597, 1563, 1508, 1349, 1243, 1180, 838,
751. λmax (DMSO/H2O, 4:1)/nm (ε/M−1 cm−1) 372 (41150).
δH (d6-DMSO) 9.84 (1H, s), 9.39 (1H, s), 8.54 (2H, d, J 8.4),
8.32–8.05 (9H, m), 7.79 (2H, d, J 8.8). δC (d6-DMSO) 153.1,
146.9, 141.5, 132.6, 131.5, 131.0, 127.8, 127.7, 127.0, 126.6,
125.7, 125.6, 125.2, 124.9, 124.5, 122.4, 121.6, 121.2, 118.0.
m/z (HR-MS FAB) 381.1116; [M+] requires 381.1114.
Methodologies
All titration experiments were performed in DMSO/H2O (4:1)
with a receptor concentration of 3 × 10−5 M. The quartz cuvette

Highly Selective Colorimetric and Fluorescent Chemodosimeters for Mercury Ion
335
(1 cm path length) was kept in a cell holder thermostatted at
25◦C. Typically, aliquots of a fresh nitrate salt standard solu-
tion of the cation of interest were added and the UV-vis and
fluorescence spectra of the samples were recorded.
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Accessory Publication
The competitive spectra of 1–3, 13C NMR spectra of 1 and 4, and
UV-vis titration spectra of 2 and 3 are available on the Journal’s
website.
Acknowledgements
We thank the National Science Council of the Republic of China for financial
support (NSC-98–2119-M-126–001-MY2).
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