Analyst

PAPER

Publ

ishe

d on

10

July

201

3. D

ownl

oade

d by

Uni

vers

idad

e Fe

dera

l do

Para

na o

n 29

/08/

2013

05:

58:5

1.

View Article OnlineView Journal | View Issue

aKey Laboratory of Green Chemistry and Tec

Chemistry, Sichuan University, Chengdu,

xqyu@scu.edu.cn; wangxin@scu.edu.cn;

28-85415886bState Key Laboratory of Biotherapy, West Ch

Sichuan University, Chengdu 610041, China

† Electronic supplementary information (See DOI: 10.1039/c3an00979c

Cite this: Analyst, 2013, 138, 5762

Received 15th May 2013Accepted 9th July 2013

DOI: 10.1039/c3an00979c

www.rsc.org/analyst

5762 | Analyst, 2013, 138, 5762–576

A BINOL-based ratiometric fluorescent sensor for Zn2+

and in situ generated ensemble for selective recognitionof histidine in aqueous solution†

Shu-Yan Jiao,a Ling-Ling Peng,b Kun Li,*a Yong-Mei Xie,b Mei-Zhen Ao,a Xin Wang*a

and Xiao-Qi Yu*a

A novel BINOL-based ratiometric fluorescent sensor (R2) is presented, which can selectively respond to Zn2+

over Cd2+ and other metal ions with fluorescence enhancement in aqueous solution. The R2 was

successfully applied in the imaging of Zn2+ in living cells. Additionally, the in situ generated R2-Zn(II)

ensemble could further serve as a probe to distinguish histidine from other amino acids via a

displacement mode.

Introduction

As the second-most abundant transition metal ion in thehuman body for sustaining life, Zn2+ is actively involved indiverse biological processes such as regulation of enzymes, geneexpression, structural cofactors, neural signal transmission,and others.1,2 Moreover, free zinc pools exist in some tissues,such as the brain, intestines, pancreas, and retina. Unlike othercations, such as Na+, K+, and Ca2+, the exact biological roles ofZn2+ are still not completely understood, because of the lack ofversatile analysis techniques for monitoring the distributionof zinc ions in cells and tissues.3 Therefore, sensitive andselective chemosensors are highly desirable to detect Zn2+ inbiological systems.

A sensor for metal ions mainly contains two parts: a uo-rophore and the coordination center. Usually, the coordinationcenter plays an important role in the selectivity of the probes. Sofar, the reported Zn2+ chemosensors have mainly employedrhodamine,4,5 courmarin,6,7 uorescein,8 anthracene9 and pyr-ene10 etc. as uorophores, and utilized di-2-picolylamine,11–13

quinoline,14–16 Schiff base,17,18 triazole19,20 and polymer21,22 etc. asthe coordination center, most of which exhibited good selec-tivity and sensitivity. Currently, it is still a challenge to developchemosensors that can distinguish Zn2+ from Cd2+, sincecadmium and zinc are in the same group of the periodic tableand exhibit highly similar spectral responses when coordinated

hnology, Ministry of Education, College of

610064, China. E-mail: kli@scu.edu.cn;

Fax: +86 28-85415886; Tel: +86

ina Hospital, West China Medical School,

ESI) available: NMR and HRMS spectra.

8

with a uorescent sensor. Thus, it is desirable to develop ahighly selective and sensitive uorescence sensor for Zn2+

detection without interference from Cd2+. Although manyratiometric uorescent chemosensors for zinc ions have beenreported in the literature,23 BINOL-based ratiometric uores-cent chemosensors for Zn2+ are scarce, especially, those whichcan realize imaging in living cells. BINOL and its derivativeshave attracted particular attention for uorescence-basedmolecular recognition.24 Recently, our group reported a BINOL-based probe for Cu2+.25 To extend our study, we wanted todesign a BINOL-based sensor for Zn2+, utilizing the hydroxylgroup in the BINOL skeleton, and introducing an auxiliarygroup for collaboration. This kind of synergy between theuorophore and the receptor (coordination center) might causeobvious changes in the spectra, once coordinated with themetal ions.

Additionally, Zn2+ is an integral part of biology because ofits role as a cofactor in various metalloproteins and metal-loenzymes. According to themetal/amino acid preferences, Zn2+

can bind to the amino acid site of these proteins which exhibitparticular enzymatic/catalytic activity/function. Recently, manymetal complexes have been applied in the selective recognitionof amino acids,26,27 but only a few metal complexes havegood selectivity, especially for Zn(II)-complexes. Therefore,developing Zn(II)-complexes as ensembles for amino acids hasreceived extensive attention.

To overcome the challenges mentioned above, herein, apyridine-2-hydrozine functionalized BINOL Schiff base R2 waspresented as a “turn-on” chemosensor, which could exhibit aratiometric signal response to Zn2+ and has been successfullyapplied in imaging Zn2+ in live cells. Moreover, the in situgenerated R2-Zn(II) ensemble (ISRE) could further serve as aprobe for the selective recognization of histidine (His) inaqueous solutions.

This journal is ª The Royal Society of Chemistry 2013

Fig. 1 Ratio of emissions (I550 nm/I500 nm) of R1 (blue bars), R2 (red bars), R3(green bars) to various metal ions in CH3CN/HEPES (10 mM, pH ¼ 7.4) ¼ 1 : 1(v/v), lex ¼ 350 nm.

Paper Analyst

Publ

ishe

d on

10

July

201

3. D

ownl

oade

d by

Uni

vers

idad

e Fe

dera

l do

Para

na o

n 29

/08/

2013

05:

58:5

1.

View Article Online

Results and discussion

R1 was readily prepared from commercially available materialsthrough a one-step reaction in ethanol at room temperature(Scheme 1). R2 and R3 were synthesized by similar proceduresusing the corresponding benzaldehyde and 2-hydrazinopyr-idine or phenylhydrazine in ethanol. Compared to R2, R3 lacksone coordinated atom (carbon is present instead of nitrogen),which may result in different coordination abilities. All of thesecompounds were characterized by NMR, HRMS.

To understand the coordination ability of the sensors, theuorescence response of R1, R2 and R3 (10 mM) in the presenceof various metal ions such as Zn2+, Cd2+, Co2+, Hg2+, Ca2+, Fe3+,Pb2+, Ni2+, Cr3+, Ag+, K+, Cu2+, Mg2+, Al3+, Li+ (Fig. 1 blue) weretested in CH3CN/HEPES(v/v ¼ 1 : 1). As shown in Fig. 1, R1exhibited poor selectivity and could not distinguish Zn2+ fromCd2+. This is because too many coordination sites exist in R1,and many metal ions could coordinate with it. While R2 couldselectively and ratiometrically response to Zn2+ over other metalions (Fig. 1 green). R2 gave a weak uorescent emission at500 nm in the absence of metal ions under the same conditions(quantum yield 0.28%, using quinine sulphate as a reference).Upon addition of Zn2+ (4 equiv.), the ratio of the emissionintensity at 550 nm and 500 nm (I550 nm/I500 nm) increased from0.58 to 7.63, whereas the addition of other metal ions could notcause any signicant spectral changes. In particular, nosignicant uorescence change of R2 was recorded in thepresence of Cd2+, which usually induced a comparable uo-rescence response to that of Zn2+ in other reported works.28

However, almost no uorescence intensity changes of R3 wereobserved in the presence of various metal ions (Fig. 1 red). Thedifferent results between R2 and R3 suggested that the N of thepyridine in R2 participated in coordination to Zn2+. Moreover, anaphthol-pyridinehydrazone based compound (R4, ESI,Fig. S1†) was also synthesized, and the uorescence resultsindicated that no ratiometric response but only intensity

Scheme 1 Synthesis route for the sensors R1/R2/R3.

This journal is ª The Royal Society of Chemistry 2013

enhancement was found for Zn2+, and it could not distinguishZn2+ from Cd2+. These results proved the importance of theBINOL skeleton (Fig. 2).

To better investigate the practical applicability of R2,competitive experiments were carried out in the presence of Zn2+

(30mM)mixedwithLi+Cd2+, Co2+, Ca2+, Fe3+, Pb2+,Ni2+,Cr3+, Ag+,K+, Cu2+, Mg2+, Al3+, Hg2+ (30 mM). As shown in Fig. 3, there wasno signicant interference from most other competitive metalions except for Fe3+, Cr3+, Al3+, Cu2+. The quantitative analyticalbehaviour of R2 for the analysis of Zn2+ was examined by uo-rescence titration. As displayed in Fig. 4, R2 displayed weakuorescence emission at 500 nm, upon gradual addition of Zn2+

to the probe, the emission intensity at around 500–550 nmincreased signicantly. A red shi of 50 nm in the maximalemission (from 500 to 550 nm) and 7.63-fold enhancement ofuorescent intensity were found. The emission intensity ratio(I550 nm/I500 nm) was found to be 0.58–7.63 in the absence andpresence of Zn2+ (4 equiv.), respectively. Satisfactory nonlinearcurve tting (the correlation coefficient is 0.9971, inset of Fig. 4)

Fig. 2 Fluorescence spectra of R2 (10 mM) in CH3CN/HEPES (10 mM, pH¼ 7.4)¼1 : 1 (v/v). Upon addition of (30 mM) various metal ions. lex ¼ 350 nm.

Analyst, 2013, 138, 5762–5768 | 5763

Fig. 3 Ratio of emissions (I550 nm/I500 nm) of R2 with 3 equiv. of various metalions in the absence and presence of Zn2+ in CH3CN/HEPES (10 mM, pH ¼ 7.4) ¼1 : 1 (v/v), lex ¼ 350 nm.

Fig. 5 UV spectra of R2 obtained during titrationwith 0–4 equiv. Zn2+ in CH3CN/HEPES (v/v ¼ 1 : 1, pH ¼ 7.4).

Analyst Paper

Publ

ishe

d on

10

July

201

3. D

ownl

oade

d by

Uni

vers

idad

e Fe

dera

l do

Para

na o

n 29

/08/

2013

05:

58:5

1.

View Article Online

conrmed that R2 and Zn2+ formed a complex with 1 : 1 stoi-chiometry. A Job plot for the complextion also showed a 1 : 1stoichiometry (Fig. S2†). Moreover, HRMS was used to conrmthe 1 : 1 bindingmode of theR2-Zn2+ complex. The peak atm/z¼468.0717 was found to correspond to the R2-Zn2+ complex. Theassociation constant was Kass ¼ 1.83 � 105 M�1, which wascalculated by using the following equation:29

I ¼ I0 + (Ilim � I0)/2C0{CH + CG

+ 1/Kass[(CH + CG + 1/Kass)2 � 4CHCG]

1/2}

where I represents the ratio of emissions (I550 nm/I500 nm), CH

and CG are the R2 and Zn2+concentration, and C0 is the initialratio of emissions (I550 nm/I500 nm) of R2. And the detection limit

Fig. 4 Fluorescence emission spectra of R2 upon addition of Zn2+, in CH3CN/HEPES35 mM, 40 mM) Inset: changes in ratio of emissions (I550 nm/I500 nm) of R2 upon adnon-linear curve fitting is 0.9971.

5764 | Analyst, 2013, 138, 5762–5768

was estimated to be 2.2 � 10�6 M (Fig. S3†). All the resultsindicated that R2 was an excellent ratiometric uorescentsensor for Zn2+.

The UV-vis absorption spectra of R2 in the presence ofvarious concentrations of Zn2+ were also studied. When Zn2+

was gradually added (CH3CN/HEPES, v/v ¼ 1 : 1), the maximumabsorbance shied from 340 to 352 nm. Meanwhile, theabsorbance at 390 nm decreased, while the absorbance at280 nm and 370 nm increased simultaneously (Fig. 5). Addi-tionally, the colour of the solution changed from colourless toorange under the UV lamp (Fig. S4†). These results furtherproved that complexation had occurred between R2 and Zn2+.

In addition to selectivity, for biological applications, it is veryimportant that the sensor is suitable for measuring specic

¼ 1 : 1 (v/v), [R2] ¼ 10 mM, [Zn2+] ¼ (5 mM, 10 mM, 15 mM, 20 mM, 25 mM, 30 mM,dition of Zn2+.The line is a line-fitted curve. The correlation coefficient (R) of the

This journal is ª The Royal Society of Chemistry 2013

Fig. 6 Fluorescence images of live HeLa cells. Top: bright images. Bottom:fluorescence images. Top (a–c), left to right: cells were incubated without probeR2, cells were incubated with R2 (10 mM) for 30 min. Bottom (d–f), cells wereincubated without R2, cells were incubated with R2 and then with Zn2+ (50 mM)and pyrithione (50 mM) for 30 min.

Paper Analyst

Publ

ishe

d on

10

July

201

3. D

ownl

oade

d by

Uni

vers

idad

e Fe

dera

l do

Para

na o

n 29

/08/

2013

05:

58:5

1.

View Article Online

metal ions in the physiological pH range. Therefore, we inves-tigated the uorescence intensity of R2 in the absence andpresence of Zn2+ at various pH values. R2 exhibited stableemission intensity at a pH range from 3.2 to 11.5 in the absenceof zinc ions (Fig. S5†). However, Zn2+ could induce uorescenceenhancement in the pH range from 5 to 10, and resulted in thestrongest uorescence enhancement at pH ¼ 7.2. These resultssuggested that R2 might be applied in biological applications.

To demonstrate the biological application of the chemo-sensor, the application of R2 for uorescence imaging of Zn2+ in

Fig. 7 Partial 1H NMR spectra (400 MHz) of R2 in d6-DMSO with titration of vario

This journal is ª The Royal Society of Chemistry 2013

living HeLa cells was investigated. As observed by laser scan-ning confocal microscopy, no uorescence in the HeLa cells wasfound in the absence of R2 (Fig. 6d). Aer incubating HeLa cellswith R2 (10 mM R2 for 30 min at 37 �C), weak intracellularuorescence was observed. However, when the cells weresubsequently incubated with Zn2+ (50 mM, with pyrithione 50mM) at 37 �C for another 30 min, a signicant uorescenceincrease from the intracellular area was observed (Fig. 6). Theseresults suggested that R2 could be successfully applied in theimaging of Zn2+ in living cells.

To evaluate the binding mode between R2 and Zn2+, a 1HNMR experiment also was carried out (Fig. 7). Upon addition ofZn2+ to a solution of R2 in d6-DMSO, the signals for Hb and Hc

gradually broadened. In addition, the peak for Hb shiedupeld, while the Hc peak shied downeld (Fig. S6†), indi-cating that N3 coordinated with the Zn2+ cation. The signals forHa and Hh separated into two distinguishable peaks, suggestingthat O1 also participated in coordination with the Zn2+ cation.The signals for He, Hd, and Hf, all on the pyridine ring, under-went downeld shis, respectively, suggesting that pyridinyl N1

also coordinate to the Zn2+(Fig. 7).To further understand the coordination properties of R2

towards Zn2+, DFT calculations with the B3LYP functional wereperformed by using the Gaussian 03 package. Geometries wereoptimized using the 6-31G* basis set and the binding energieswere estimated by the 6-31G* basis set. The optimized cong-uration is shown in Fig. 8, it indicates that Zn2+ was wellchelated by the O1, N2 and N3 of R2. The Zn–O1 bond lengthis 1.941 A, the Zn–N bond lengths are 2.004 (Zn–N1) and

us equiv. of Zn2+.

Analyst, 2013, 138, 5762–5768 | 5765

Fig. 8 Optimized geometries of the R2-Zn (II) complex, color code: C (dark gray),N (blue), O (red).

Analyst Paper

Publ

ishe

d on

10

July

201

3. D

ownl

oade

d by

Uni

vers

idad

e Fe

dera

l do

Para

na o

n 29

/08/

2013

05:

58:5

1.

View Article Online

2.022 (Zn–N3), respectively. Aer calculation, we found thatthe binding energy of the structure of the R2-Zn complex was�27.8 kcal mol�1, this data indicated that R2-Zn formed a stablecomplex as shown in Fig. 8. This result is in agreement withthe uorescent titration and 1H NMR titration.

Since Zn2+ has a strong ability to form complexes with aminoacids, ISRE was then used for the recognition of amino acids byuorescence and UV-vis absorption experiments. The R2-Zn(II)complex was titrated with the 20 naturally occurring aminoacids. As shown in Fig 9, His could quench the uorescence ofthe R2-Zn2+ complex, while the other amino acids resulted invery little change to the uorescence intensity. Fluorescencequenching observed in the presence of His could be attributedmainly to the protonation of the Zn2+ coordination sphere fol-lowed by the formation of His–Zn2+complex. The dechelation ofZn2+ from R2-Zn(II) by His was further conrmed by theabsorption experiment.

Upon titration of the R2-Zn2+ ensemble with His, the uo-rescence intensity decreased gradually, the uorescence inten-sity was the same as that of R2 when 2 equiv. fo His were added(Fig. S7†), and the maximum absorption bands of R2-Zn2+

Fig. 9 Fluorescence intensity for titration of amino acids with R2-Zn(II) (2 : 1) inCH3CN/HEPES (v/v ¼ 1 : 1 pH ¼ 7.4).

5766 | Analyst, 2013, 138, 5762–5768

(Fig. S8 red line†) gradually shied from 352 nm to 340 nm. Thespectra did not change aer 2 equiv. His were added, and aresimilar to that of R2 in the absence of Zn2+ (Fig. S7 black line†).These results demonstrate that the R2-Zn2+ complex could serveas an ensemble for the selective sensing of His via a displace-ment mode.

ExperimentalGeneral

Mass spectrometry (ESI-MS) and high resolution mass spec-trometry (HRMS) data were recorded using a FinniganLCQDECA and a Bruker Daltonics Bio TOF mass spectrometer,respectively. The 1H NMR and 13C NMR spectra were measuredusing a Bruker AM400 NMR spectrometer and the d scale inppm were referenced to residual solvent peaks or internal tet-ramethylsilane (TMS). Absorption spectra were recorded usingan Hitachi U1900 spectrophotometer at 298 K. Fluorescenceemission spectra were obtained using a FluoroMax-4 Spectro-uorophotometer (HORIBA Jobin Yvon) at 298 K. The MDA-MB-231 cells were analyzed in an ArrayScan VTI HCS Reader(Thermo Fisher Scientic, Inc.). Unless otherwise indicated, allsyntheses and manipulations were carried out under an N2

atmosphere. All the solvents were dried according to thestandard methods prior to use. All of the solvents were eitherHPLC or spectroscopic grade in the optical spectroscopicstudies.

Synthesis of 2-hydrazine pyridine. To a solution of2-bromopyridine (1.0 g) in ethanol (5.0 mL, 5 equiv.), hydrazinehydrate (6.6 mL, 6.6 equiv.) was added and the reaction mixturewas heated to reux for 30 hours. Progress of the reaction wasmonitored by TLC (40% ethyl acetate/hexane, Rf � 0.1). Oncompletion of the reaction, ethanolic hydrazine hydrochloridewas distilled off completely at 100 �C, the residue was taken inDCM (50 mL) and the contents were washed with saturatedsodium carbonate solution (20 mL). The combined organiclayer was dried over sodium sulfate and concentrated underreduced pressure to obtain the crude product as a low meltingsolid (0.5 g, crude). The crude product obtained was directlyused for the next step.

General procedure for the preparation of R1. 1.0 mmol 1 and2.0 mmol 2-hydrazine pyridine were dissolved in absoluteethanol. The mixture was reuxed overnight, aer drying underreduced pressure; products were obtained in 82% yield. ESI-MS:m/z 525.2038 (M+1), 1H NMR (d6-DMSO) d (ppm): 6.78 (t, 2H, J¼4.0 Hz), 6.89 (d, 2H, J ¼ 8.0 Hz), 7.00 (d, 2H, J ¼ 8.0 Hz), 7.26 (t,2H, J ¼ 8.0 Hz), 7.33 (t, 2H, J ¼ 8.0 Hz), 7.59 (t, 2H, J ¼ 8.0 Hz),7.99 (d, 2H, J ¼ 12.0 Hz), 8.13 (d, 2H, J ¼ 4.0 Hz), 8.17 (s, 2H),8.53 (s, 2H), 11.19 (s, 2H), 11.29 (s, 2H). 13C NMR (100 MHz,CDCl3), d (ppm): 106.3, 115.6, 116.0, 121.4, 123.3, 124.1, 127.1,127.8, 128.4, 129.4, 133.5, 138.2, 141.6, 148.1, 151.8, 155.4.

General procedure for the preparation of R2. 1.0 mmol 2 and1.0 mmol 2-hydrazine pyridine were dissolved in absoluteethanol. The mixture was reuxed overnight, aer drying underreduced pressure; products were obtained in 92% yield. ESI-MS:m/z 428.1371 (M + Na), 1H NMR (d6-DMSO) d (ppm): 6.80 (t, 1H,J ¼ 4.0 Hz), 6.89 (d, 1H, J ¼ 8.0 Hz), 6.97 (d, 2H, J ¼ 8.0 Hz), 7.19

This journal is ª The Royal Society of Chemistry 2013

Paper Analyst

Publ

ishe

d on

10

July

201

3. D

ownl

oade

d by

Uni

vers

idad

e Fe

dera

l do

Para

na o

n 29

/08/

2013

05:

58:5

1.

View Article Online

(t, 1H, J ¼ 8.0 Hz), 7.25 (d, 2H, J ¼ 8.0 Hz), 7.31 (t, 1H, J ¼ 8.0Hz), 7.36 (d, 1H, J¼ 12.0 Hz), 7.62 (d, 1H, J¼ 8.0 Hz), 7.89 (t, 2H,J¼ 8.0 Hz), 7.96 (d, 1H, J¼ 4.0 Hz), 8.14 (s, 2H), 8.52 (s, 1H), 9.33(s, 1H), 11.10 (s, 1H), 11.32 (s, 1H). 13C NMR (100MHz, CDCl3), d(ppm): 106.7, 114.8, 114.9, 116.3, 118.4, 120.6, 123.4, 124.1,124.8, 124.9, 126.7, 128.1, 128.2, 128.3, 128.5, 129.3, 130.1,131.4, 133.8, 134.2, 138.6, 142.4, 146.8, 152.0, 152.6, 154.8.

General procedure for the preparation of R3. 1.0 mmol 2 and1.0 mmol phenylhydrazine were dissolved in absolute ethanol.The mixture was reuxed overnight, aer drying under reducedpressure; products were obtained in 88% yield. ESI-MS: m/z427.1425 (M + Na), 1H NMR (d6-DMSO) d (ppm): 6.78 (t, 1H, J ¼8.0 Hz), 6.91 (d, 2H, J¼ 8.0 Hz), 6.97 (t, 2H, J¼ 8.0 Hz), 7.17–7.27(m, 5H), 7.30 (t, 1H, J¼ 8.0 Hz), 7.36 (d, 1H, J¼ 12.0 Hz), 7.89 (t,2H, J ¼ 8.0 Hz), 8.10 (s, 2H), 8.28 (s, 1H), 8.32 (s, 1H), 10.76 (s,1H), 11.07 (s, 1H). 13C NMR (100 MHz, CDCl3), d (ppm): 112.9,117.8, 120.9, 121.8, 123.4, 124.1, 124.7, 124.9, 126.7, 127.9,128.4, 129.3, 129.4, 130.2, 130.7, 133.8, 140.1, 142.9, 151.5,152.8, 171.4.

Conclusion

In conclusion, we have synthesized a series of uorescentsensors based on BINOL for Zn2+. R2 was highly selective andratiometric for Zn2+. Especially, R2 was not affected by Cd2+.Confocal uorescence microscopy experiments suggested thatR2 could successfully penetrate live cells and image Zn2+.Additionally, the ISRE showed high selectivity to His in thepresence of arious amino acids and sensed His through adisplacement mechanism.

Acknowledgements

This work was nancially supported by the National Program onKey Basic Research Project of China (973 Program,2012CB720603 and 2013CB328900) and the National ScienceFoundation of China (nos 21232005 and 21001077). We alsothank the Analytical & Testing Center of Sichuan University forNMR analysis.

Notes and references

1 (a) Y.-P. Li, H.-R. Yang, Q. Zhao, W.-C. Song, J. Han andX.-H. Bu, Inorg. Chem., 2012, 51, 9642; (b) X.-Y. Zhou,B.-R. Yu, Y.-L. Guo, X.-L. Tang, H.-H. Zhang and W.-S. Liu,Inorg. Chem., 2010, 49, 4002; (c) J. M. Berg and Y. Shi,Science, 1996, 271, 1081.

2 (a) S. C. Burdette and S. J. Lippard, Proc. Natl. Acad. Sci.U. S. A., 2003, 100, 3605; (b) G. K. Andrews, BioMetals,2001, 14, 223.

3 (a) P.-W. Du and S. J. Lippard, Inorg. Chem., 2010, 49, 10753;(b) Y.-X. Chen, J. Shi, Y.-M. Li, F.-L. Wang, X. Wu, Q.-X. Guoand L. Liu, Org. Lett., 2009, 11, 4426; (c) G. K. Walkup,S. C. Burdette, S. J. Lippard and R. Y. Tsein, J. Am. Chem.Soc., 2000, 122, 5644; (d) L. Xue, Z.-J. Fang, G.-P. Li,H.-H. Wang and H. Jiang, Sens. Actuators, B, 2011, 156, 410.

This journal is ª The Royal Society of Chemistry 2013

4 (a) H.-H. Wang, L. Xue, C.-L. Yu, Y.-Y. Qian and H. Jiang, DyesPigm., 2011, 91, 350; (b) P.-W. Du and S. J. Lippard, Inorg.Chem., 2010, 49, 10753; (c) J.-F. Zhang, Y. Zhou, J. Yoon,Y. Kim, S. J. Kim and J. S. Kim, Org. Lett., 2010, 12, 3852.

5 (a) H. Sasaki, K. Hanoka, Y. Urano, T. Terai, T. Nagano andD. Chellappa, Bioorg. Med. Chem., 2011, 19, 1072; (b)G. Sivcvraman and T. Anand, Analyst, 2012, 137, 5881; (c)Z.-X. Han, X.-B. Zhang, L. Zhuo, Y.-J. Gong, X.-Y. Wu,J. Zhen, C.-M. He, L.-X. Jian, Z. Jing, G.-L. Shen andR.-Q. Yu, Anal. Chem., 2010, 82, 3108.

6 (a) S. Sumiya, Y. Shiraishi and T. Hirai, J. Phys. Chem. A, 2013,117, 1474; (b) C. P. Kulatilleke, S. A. de Silva and Y. Eliav,Polyhedron, 2006, 25, 2593; (c) M.-H. Yan, T.-R. Li andZ.-Y. Yang, Inorg. Chem. Commun., 2011, 14, 463.

7 (a) K. Komatsu, Y. Urano, H. Kojima and T. Nagano, J. Am.Chem. Soc., 2007, 129, 13347; (b) H.-Y. Li, S. Gao and Z. Xi,Inorg. Chem. Commun., 2009, 12, 300.

8 (a) S. C. Burdette, G. K. Walkup, B. Spingler, R. Y. Tsein andS. J. Lippard, J. Am. Chem. Soc., 2001, 123, 7831; (b) L. Jiang,L. Wang, M. Guo, G. Yin and R.-Y. Wang, Sens. Actuators, B,2011, 159, 148; (c) K. Komatsu, K. Kikuchi, H. Kojima,Y. Unora and T. Nagano, J. Am. Chem. Soc., 2005, 127, 10197.

9 (a) A. Tarraga and P. Molina, Org. Lett., 2007, 9, 2385; (b)S. J. Park, J. H. Yoon, C. J. Hong, R. Souane, J. Y. Kim,S. E. Mattews and Vicens, J. Org. Chem., 2008, 73, 8212; (c)J. M. Choi, D. Kim and J. Yoon, Bioorg. Med. Chem. Lett.,2010, 20, 125.

10 (a) H. Yuasa, N. Miyagawa, M. Izumi and H. Hashimoto, Org.Lett., 2004, 6, 1489; (b) V. Banjoke, Y.-Q. Xu, E. Mintz andY. Pang, Polymer, 2009, 50, 2001.

11 (a) L. Xue, H.-H. Wang, X.-J. Wang and H. Jiang, Inorg. Chem.,2008, 47, 4310; (b) H.-H. Wang, Q. Gan, X.-J. Wang, L. Xue,S.-H. Liu and H. Jiang, Org. Lett., 2007, 9, 4995; (c)C. R. Goldsmith and S. J. Lippard, Inorg. Chem., 2006, 45,6474.

12 (a) L. Xue, G.-P. Li, D.-J. Zhu, Q. Liu and H. Jiang, Inorg.Chem., 2012, 51, 10842; (b) L. Xue, H.-H. Wang, X.-J. Wangand H. Jiang, Inorg. Chem., 2008, 47, 4310; (c) B. A. Wang,S. Friedle and S. J. Lippard, Inorg. Chem., 2009, 48, 7009.

13 (a) S. C. Burdette, C. J. Ferderichson, W. M. Bu andS. J. Lippard, J. Am. Chem. Soc., 2003, 125, 1778; (b)F. Qian, C.-L. Zhang, Y.-M. Zhang, W.-J. He, X. Gao, P. Huand Z.-J. Guo, J. Am. Chem. Soc., 2009, 131, 1460; (c)Z.-C. Xu, K. H. Baek, H. N. Kim, J. N. Cui, X. K. Qian,D. R. Spring, I. Shin and J. Y. Yoon, J. Am. Chem. Soc.,2010, 132, 601; (d) C.-J. Chang, J. Jaworshi, E. M. Nolan,M. Sheng and S. J. Lippard, Proc. Natl. Acad. Sci. U. S. A.,2004, 101, 1129.

14 (a) Y. Weng, Z.-L. Chen, F. Wang, L. Xue and H. Jiang, Anal.Chim. Acta, 2009, 647, 215; (b) Y.-L. Cai, X.-M. Meng,S.-J. Wang, M.-Z. Zhu, Z.-W. Pan and Q.-X. Guo,Tetrahedron Lett., 2013, 54, 1125; (c) L. Praveen,C. H. Suresh, M. L. P. Reddy and R. L. Varma, TetrahedronLett., 2011, 52, 4730.

15 (a) X.-Y. Zhou, B. Yu, Y.-L. Guo, X.-L. Tang, H.-H. Zhang andW.-S. Liu, Inorg. Chem., 2010, 49, 4002; (b) R. T. Bronson,J. S. Bradshaw, P. B. Savage, S. Fuangswasdi, S. C. Lee,

Analyst, 2013, 138, 5762–5768 | 5767

Analyst Paper

Publ

ishe

d on

10

July

201

3. D

ownl

oade

d by

Uni

vers

idad

e Fe

dera

l do

Para

na o

n 29

/08/

2013

05:

58:5

1.

View Article Online

K. E. Krakowiak and R. M. Izatt, J. Org. Chem., 2001, 66, 4752;(c) K. Rurack, Spectrochim. Acta, Part A, 2001, 57, 2161.

16 Q. H. You, P. S. Chan, W. H. Chan, S. C. K. Hau, A. W. M. Lee,N. K. Mak, T. C. W. Mak and R. N. S. Wong, RSC Adv., 2012, 2,11078.

17 (a) T.-B. Wei, P. Zhang, B.-B. Shi, P. Chen, Q. Lin, J. Liu andY.-M. Zhang, J. Org. Chem., 2012, 77, 7157; (b) D. Roy,K. Dhara, M. Manassero, J. Ratha and P. Banerjee, Inorg.Chem., 2007, 46, 6405.

18 (a) L.-N. Wang, W.-W. Qin, X.-L. Tang, W. Dou and W.-S. Liu,J. Phys. Chem. A, 2011, 115, 1609; (b) L.-N. Wang, W.-W. Qinand W.-S. Liu, Inorg. Chem. Commun., 2010, 13, 1122; (c)W. H. Hsieh, C. F. Wan, D. J. Liao and A. T. Wu,Tetrahedron Lett., 2012, 53, 5848.

19 (a) R. K. Pathak, V. K. Hinge, A. Pai, D. Panda and C. P. Rao,Inorg. Chem., 2012, 51, 4994; (b) S. Huang, R. J. Clark andL. Zhu, Org. Lett., 2007, 9, 4999.

20 (a) A. Misra, M. Shahid and P. Srivastava, Sens. Actuators, B,2012, 169, 327; (b) Y. Shiraishi, Y. Kohno and T. Hirai, J. Phys.Chem. B, 2005, 109, 19139.

21 (a) F.-Y. Song, X. Ma, J.-L. Hou, X.-B. Huang, Y.-X. Cheng andC.-J. Zhu, Polymer, 2011, 52, 6029; (b) S. Sali, I. Grabchev,J. M. Chovelon and G. Ivanova, Spectrochim. Acta, Part A,2006, 65, 591.

22 (a) K. Shen, X. Yang, Y.-X. Cheng and C.-J. Zhu, Tetrahedron,2012, 68, 5719; (b) X.-H. Qian, J.-N. Cui and R. Zhang,Tetrahedron, 2006, 62, 556; (c) W.-C. Song, J. Han andX.-H. Bu, Inorg. Chem., 2012, 51, 9642.

5768 | Analyst, 2013, 138, 5762–5768

23 (a) S. Deo and H. A. Godwin, J. Am. Chem. Soc., 2000, 122,174; (b) Z.-P. Liu, C.-L. Zhang, X.-Q. Wang, W.-J. He andZ.-J. Guo, Org. Lett., 2012, 14, 4378; (c) S. Atilgan,T. Ozdermir and E. U. Akkaya, Org. Lett., 2008, 10, 4065.

24 (a) X. Yang, X.-C. Liu, K. Shen and C.-J. Zhu, Org. Lett., 2011,13, 3510; (b) Y.-W. Wang, Y.-T. Shi, Y. Peng, A.-J. Zhang,T.-H. Ma, D. Wei and J.-R. Zheng, Spectrochim. Acta, Part A,2009, 72, 322; (c) M. Dong, Y.-M. Dong, T.-H. Ma andY.-W. Wang, Inorg. Chim. Acta, 2012, 381, 137–142; (d)T.-H. Ma, A.-J. Zhang, M. Dong, Y.-M. Dong, Y. Peng andY.-W. Wang, J. Lumin., 2010, 130, 888–892; (e) L. Pu, Chem.Rev., 1998, 98, 2405–2494; (f) L. Pu, Chem. Rev., 2004, 104,1687–1716; (g) K. Shen, X. Yang, Y.-X. Cheng and J. Zhu,Tetrahedron, 2012, 68, 5719–5723.

25 M.-Q. Wang, K. Li, J.-T. Hou, M.-Y. Wu, Z. Huang andX.-Q. Yu, J. Org. Chem., 2012, 77, 8350.

26 (a) Z. Huang, J. Du, J. Zhang, X.-Q. Yu and L. Pu, Chem.Commun., 2012, 48, 3412; (b) R. Joseph, J. P. Chinta andC. P. Rao, J. Org. Chem., 2010, 75, 3387.

27 (a) H. L. Kwong, W. L. Wong, C. S. Lee, C. T. Yeung andP. F. Teng, Inorg. Chem. Commun., 2009, 12, 815; (b)R. K. Pathak, K. Tabbasum, A. Rai, D. Panda and C. P. Rao,Analyst, 2012, 137, 4069.

28 (a) P.-F. Wang, H.-Y. Zhang and J.-J. Ma, Tetrahedron, 2012, 8,5458; (b) S. Sumiya, Y. Shiraishi and T. Hirai, J. Phys. Chem. A,2013, 117, 1474.

29 B. Valeur, J. Pouget and J. Bourson, J. Phys. Chem., 1992, 96,6545–6549.

This journal is ª The Royal Society of Chemistry 2013