1
554
B. Yang, W. Wu / Reactive & Functional Polymers 73 (2013) 1553–1558
solvent–water solutions. As the organic solvent which has low
boiling point was volatile, if the detection system was placed for
a long time before use, the concentration changes of the liquid
detection system should affect the detection accuracy. In addition,
the detection was often manipulated in transparent glassware,
such as in a test tube. We should take many brittle glasswares
along with the liquid detection system if we want to conduct on-
site detection. Hence this liquid detection system was not conve-
cooling to the room temperature, the above mixture solution was
dried by reduced pressure distillation for about 30 min until the
vacuum degree of the instrument was higher than 0.08 MPa so that
there was no clear liquid. 1 mol/L HCl (75 mL) was added to the
resultant in the flask to generate a transparent red solution. After
that, 1 mol/L NaOH (80 mL) was added slowly with stirring until
the pH value of the solution reached 9–10. The resulting precipi-
tate was filtered and washed 3 times with distilled water, and then
the precipitate was collected and dried in a vacuum oven for 48 h
2
+
nient to conduct on-site detection for the detection of Hg . In
the Ma’s [23] and Wu’s [24] work, the filter paper was immersed
into the rhodamine derivatives solution in order to immobilize
the rhodamine derivatives onto the filter paper surface, respec-
tively. They purposed to prepare a kind of portable and convenient
1
to provide a pink solid (2.024 g, yield: 88.9%). H NMR (d-DMSO,
400 MHz, ppm):d1.10(t, 12H, NCH
4.28(s, 2H, NH ), 6.34(q, 4H, Xanthene-H), 6.37(d, 2H, Xanthene-
H), 7.00(q, 1H, Ar-H), 7.48(m, 2H, Ar-H), 7.77(q, 1H, Ar-H).
2 3 2 3
CH ), 3.33(q, 8H, NCH CH ),
2
2
+
Hg -indicating paper. However, the probes were just only physi-
cally adsorbed onto the substrate, so the probe should be easy
washed away or dissolved by the solvent when one conduct the
detection. This would affect the detection accuracy, even leading
to the failure of the detection system. As the result, a portable, con-
venient and a accurate-measureable system for the mercury ion
detection will be required to meet the practical on-site application.
Herein we report the design and preparation of a cellulose-
based paper fluorescent chemodosimeter for the detection of
2
.3.2. Preparation of Bromobenzene-modified cellulose paper (1)
The clean filter paper was cut to be 18 ꢀ 18 mm per piece. And
then the cut papers were washed with sequence of 0.5 mol/L
H SO , 0.5 mol/L NaOH, EtOH and distilled water, then the papers
2 4
were dried in the oven for the next reaction.
To a 50 mL flask, 6 pieces of cellulose paper with a dimension of
8 ꢀ 18 mm were immersed into 30 mL dry DMF. 0.25 g NaH was
1
added and the mixture was degassed for 15 min. Then 4-Bromob-
enzyl bromide dissolved in 5 mL dry DMF was slowly added drop-
wise to the flask, and the solution was stirred at room temperature
2
+
Hg . The Rhodamine B derivative was covalently grafted to the
2
+
cellulose paper through grafting-to technique and the Hg -indi-
2+
cating paper was prepared. While the Hg -indicating paper was
2
under N for 20 h. Then compound 1 were all taken out and
2
+
immersed into the Hg solution, the fluorescence enhancement
and the color change can be discerned by naked eyes under the
irradiation of 365 nm UV light. We investigated in detail the
washed twice with sequence of acetone, DMF, distilled water and
EtOH. At last, the sample was Soxhlet extracted for 24 h and dried
in a vacuum oven.
2
+
2+
Hg -sensing capabilities of the Hg -indicating paper. To the best
of our knowledge, there was no information available in literatures
about Rhodamine B-grafting cellulose paper to prepare a fluores-
2.3.3. Preparation of Ally isothiocyanate-modified cellulose paper (2)
To a 50 mL flask, compound 1 (18 ꢀ 18 mm, 6 pieces) were im-
mersed into 30 mL dry DMF. Aqueous solution of potassium bicar-
bonate (0.2 M, 3 mL) and 0.1 mL ally isothiocyanate were added
2
+
cent and colorimetric chemodosimeter for the detection of Hg
. Experimental
.1. Materials
Rhodamine B (AR, 98%) was purchased from Aladdin-reagent.
.
2
and the mixture was degassed for 15 min and then Pd(PPh
2 mol%, 24 mg) was added under N protection. The above mix-
ture was refluxed at 80 °C under N for 24 h. After cooling to RT,
3 4
)
(
2
2
2
compound 2 were all taken out and washed twice with sequence
of acetone, DMF, distilled water and EtOH. At last, the sample
was Soxhlet extracted for 24 h and dried in a vacuum oven.
Ally isothiocyanate (AR, 97%) was supplied by Shijiazhuang Lida
Chemicals Co., Ltd. Tetrakis-(triphenylphosphine) palladium (AR,
9
(
9.5%) was obtained from Synwitech. 4-Bromobenzyl bromide
AR, 98%) was provided by Beijing Coupling Technology Co., Ltd.
Acetonitrile (MeCN) and N,N-Dimethylformamide (DMF) were
dried over CaH and distilled just prior to use. Other reagents
2
+
2.3.4. Preparation of Hg -indicating paper (3)
To a 50 mL flask, compound 2 (18 ꢀ 18 mm, 6 pieces) were im-
2
mersed into 30 mL dry MeCN. RhBNH (23 mg, 0.05 mmol) was
2
and solvents obtained from commercial suppliers were used with-
out further purification.
added and then the mixture was refluxed at 80 °C for 24 h. After
cooling to RT, compound 3 were all taken out and washed twice
with sequence of acetone, DMF, distilled water and EtOH. At last,
the sample was Soxhlet extracted for 24 h and dried in a vacuum
oven (Scheme 1).
2.2. Instrumentation
1H spectra were recorded on a Bruker AVANCE DRX 400 NMR
spectrometer. FT-IR spectra were obtained using a Bruker TENSOR
7 with samples prepared as KBr disk pellets. PL spectra (at room
temperature) were recorded on Hitachi F-4500 fluorescence spec-
trophotometer. X-ray photoelectron spectroscopy data were ac-
quired with an ESCALab220i-XL electron spectrometer from VG
0
2
.3.5. Synthesis of N-allyl-N -Rhodamine B hydrazinethiourea (RhBCH)
2
To a 50 mL flask, RhBNH
0 mL of dry MeCN. Ally isothiocyanate (0.149 g, 1.5 mmol) in
dry MeCN (10 mL) was then added slowly dropwise with stirring
at room temperature. The stirred mixture was heated to 80 °C for
4 h. After cooling to the room temperature, the above mixture
solution was dried by reduced pressure distillation for about
0 min until the vacuum degree of the instrument was higher than
2
(0.457 g, 1 mmol) was dissolved in
1
Scientific using 300 W Al K
a radiation. Column chromatography
2
was performed with silica gel (100–200 mesh).
3
2
2
.3. Synthesis
0.08 MPa so that there was no clear liquid. The resultant was puri-
fied by column chromatography with hexane–ethyl acetate (4:1, v/
v) to provide a pink solid (0.309 g, yield:70.1%). H NMR (d-DMSO,
1
.3.1. Synthesis of Rhodamine B hydrazine (RhBNH
2
)
To a 100 mL flask, Rhodamine B (2.40 g, 5 mmol) was dissolved
400 MHz, ppm):d1.09(t, 12H, NCH
CH
2 3
2 3
), 3.35(q, 8H, NCH CH ),
in 50 mL ethanol. 6 mL hydrazine hydrate was then added slowly
dropwise with vigorous stirring at room temperature. Then the
stirred mixture was heated to 85 °C and refluxed for 2 h. After
4.81(d, 2H, CH@CH ), 5.38–5.39(m, H, CH@CH
Xanthene-H), 7.08–7.61(m, 4H, Ar-H), 7.88(d, 1H, NH), 9.01(s,
H, -CSNH) (Scheme S1).
2
2
), 6.33(q, 6H,