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for all the water samples (see Figure S5 in the Supporting In-
formation). These results indicated that the presence of organ-
ic matter in the real water samples does not interfere with the
oxidation of cyanide to cyanate ions by 1.
Synthesis of [{Fe(tBubpy)(CN) }{Cu(dien)(ClO )} ]·CH C(O)CH
3
4
4
2
3
(1)
A mixture of K [Fe(tBubpy)(CN) ] (0.253 g, 0.5 mmol) and [Cu(dien)-
2
4
(
ClO )](ClO ) (0.366 g, 1 mmol) was stirred in water/methanol (1:1,
4 4
The signal amplification in cyanide detection in real water
samples by 1 was performed by adding small amounts of cya-
nide ions to the tap, lake, underground, and river (48, 48, 150,
and 150 ppb, respectively) water samples in the presence of
phenolphthalin in a 1:100 molar ratio of 1/phenolphthalin. The
results showed that 1 could detect tiny amounts of cyanide
ions in all of the real water samples with an excellent recovery
and good RSD values of 87.0–109.4 and 3.22–11.38%, respec-
tively (Table 2) and amplify the detection signal. The maximum
allowable level for cyanide ions in drinking water is 50–
v/v, 10 mL) at room temperature for 30 min and was allowed to
stand overnight. Brown precipitates obtained upon centrifugation
were washed with deionized water and acetone and then air dried
À1
(
0.414 g, 86.4%). IR (KBr): n˜ =2052, 2076, 2096, 2118 cm ; MS
CꢀN
(
ESI): (MeCN, positive mode): m/z calcd for: 380.1 [{Fe(tBub-
2
+
À1
py)(CN) }{Cu(dien)} ]
(mass=760.2 gmol ); elemental analysis
4
2
(
%) calcd for C Cl Cu FeH N O ·CH C(O)CH (1): C 38.91, H 5.54, N
30 2 2 50 12 8 3 3
1
6.50; found: C 39.02, H 5.61, N 16.84.
[
30]
Determination of binding constants
2
00 ppb.
II
II
For the determination of binding strengths of the Fe –Cu complex
À4
1
, solutions of K [Fe(tBubpy)(CN) ] (1.010 m) in aqueous DMF
2
4
Conclusion
(1:1, v/v; aqueous HEPES buffer (1.50 mL, pH 7.4) + DMF (1.50 mL))
were mixed with solutions of [Cu(dien)(ClO )](ClO ) in aqueous
II
II
4
4
A new bimetallic Fe –Cu complex has been synthesized and
characterized. The complex has been shown to be a multifunc-
tional molecular device that simultaneously features chemo-
sensing, signal-amplification, and catalytic–oxidation properties
for cyanide ions. The results obtained in this study show that
the complex can provide excellent performance in three tasks
DMF (1:1, v/v; aqueous HEPES buffer (1.50 mL, pH 7.4) + DMF
À4
(
1.50 mL)) of various concentrations (0–1.010 m). The absorp-
tion intensity of the resultant mixture at l=505 nm was measured
and A /(AÀA ) was plotted as
a function of 1/{[Cu(dien)(-
0
0
2
ClO
)](ClO )} .
4
4
1
) the production of naked-eye colorimetric responses specifi-
cally for cyanide ions in aqueous systems, 2) an improvement
in the visual detection of cyanide ions of approximately 80
times from 32 to 0.4 ppm, and 3) the complete oxidization of
Chemosensing selectivity of complex 1 toward various
analytes
À
42À
À3
3À
42À
3À
À
À
Various analytes (i.e., CN , SO , HCO , HPO , N , CH
3
COO ,
cyanide ions into the safer product cyanate (OCN ) ions. These
À
À
À
NCS , NO3 , and Cl ; 0–2.0010 m) were mixed with solutions of
complex 1 (2.0010 m). The titrations were carried out in aque-
multifunctional assays are workable in real water bodies, such
as from taps, rivers, lakes, and underground water bodies, with
excellent recoveries and good relative standard deviations of
À4
ous DMF (1:1, v/v) at room temperature. Spectroscopic changes of
the resulting mixtures at l=505 nm were plotted as a function of
the analyte molar ratio. The colorimetric responses of 1 to the ana-
lytes were also obtained by digital photography.
8
7.0–109.4 and 3.22–11.38%, respectively.
Experimental Section
Signal amplification by complex 1 in cyanide detection
Instrumentation
À5
Various amounts of cyanide ions (0–4.6110 m; 0–1.2 ppm) were
Electrospray (ES) mass spectrometry was performed by means of
an AB SCIEX API 2000 LC/MS/MS system. Elemental analyses were
À6
added to a mixture of 1 (2.5010 m) and phenolphthalin (2.52
À4
1
0
m). The studies were carried out at room temperature in aque-
ous solutions at pH 14. Each solution was allowed to stand for
5 min. UV/Vis absorption spectra were recorded at fixed time in-
tervals and their intensities at l=551 nm were plotted against the
cyanide concentration. The amplified colorimetric responses of
conducted on a Vario EL CHN analyzer. IR spectra in the range l=
À1
5
00–4000 cm with KBr pellets were recorded on a PerkinElmer
1
Model Frontier FTIR spectrometer. UV/Vis spectra were measured
on a Cary 50 UV/Vis spectrophotometer.
1
toward cyanide ions were also obtained by digital photography.
UV/Vis spectroscopic and spectrofluorimetric titrations
All solvents used in the UV/Vis spectroscopic titrations were of ana-
lytical grade. DMF was purified by distillation. A 10 mm 4-(2-hy-
droxyethyl)-1-piperazineethanesulfonic acid (HEPES) buffer solution
Oxidation of cyanide to cyanate ions with complex 1 as the
catalyst
at pH 7.4 was used. Except for NaN , all the anions used in the ti-
3
trations were potassium salts. Except in the signal-amplification
studies, all the titrations were carried out in aqueous DMF (1:1, v/v;
aqueous HEPES buffer (1.50 mL, pH 7.4)+DMF (1.50 mL)); the titra-
tions performed for signal amplification were carried out in deion-
ized water at pH 14. Measurements were taken after equilibrium
was reached. The receptor/substrate interaction was analyzed ac-
The experiments were conducted in a boiling tube (40 mL) in the
absence of light. A test solution (15.00 mL) was stirred during the
À
experiments; the concentrations of 1, CN , and H O were 1.00
2
2
À4
À3
À4
10 , 1.0310 , and 6.5310 m in water, respectively. The test
solution was adjusted to pH 10. The concentrations of CN and
OCN ions in the test solution were measured at regular intervals
by using reported analytical methods. The samples were ana-
À
À
[47]
[48]
cording to Benesi–Hildebrand equations for the UV/Vis spectro-
scopic titration.
lyzed immediately to avoid errors due to further reactions.
Chem. Eur. J. 2015, 21, 12984 – 12990
12989
ꢀ 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chow, Cheuk-Fai
