An ion-responsive fluorescent compound based on NO-photoisomerisation styryl derivative linked to monoaza-15-crown-5

Article abstract of DOI:10.1080/10610278.2010.532215

A novel 15-aza-5-crown ether linked to styryl chemosensory 13-(4-((9H-fluoren-9-ylidene)methyl)-2-nitrophenyl)- 1,4,7,10-tetraoxa-13- azacyclopentadecane was designed and synthesised, it would not occur during photoisomerisation under radiation of light but shows special capability of selectively recognising for Sr²⁺.

Full text of DOI:10.1080/10610278.2010.532215

This article was downloaded by: [Selcuk Universitesi]
On: 08 January 2015, At: 03:15
Publisher: Taylor & Francis
Informa Ltd Registered in England and Wales Registered Number: 1072954 Registered office: Mortimer House,
37-41 Mortimer Street, London W1T 3JH, UK
Supramolecular Chemistry
Publication details, including instructions for authors and subscription information:
http://www.tandfonline.com/loi/gsch20
An ion-responsive fluorescent compound based on
NO-photoisomerisation styryl derivative linked to
monoaza-15-crown-5
Jing Cao a b , Jun Xiang Feng a , Yong Xiang Wu a , Xue Qun Pei a , Jiao Jiao Yan a , Yang Liu a
, Wen Jie Qin a & Xiao Bin Zhang a
a College of Chemistry, Xiangtan University , Xiangtan , Hunan , 411105 , P.R. China
b Key Laboratory of Environmentally Friendly Chemistry and Application of Ministry of
Education , College of Chemistry, Xiangtan University , Xiangtan , Hunan , 411105 , P.R.
China
Published online: 15 Apr 2011.
To cite this article: Jing Cao , Jun Xiang Feng , Yong Xiang Wu , Xue Qun Pei , Jiao Jiao Yan , Yang Liu , Wen Jie Qin &
Xiao Bin Zhang (2011) An ion-responsive fluorescent compound based on NO-photoisomerisation styryl derivative linked to
monoaza-15-crown-5, Supramolecular Chemistry, 23:5, 407-410, DOI: 10.1080/10610278.2010.532215
To link to this article: http://dx.doi.org/10.1080/10610278.2010.532215
PLEASE SCROLL DOWN FOR ARTICLE
Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained
in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no
representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the
Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and
are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and
should be independently verified with primary sources of information. Taylor and Francis shall not be liable for
any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever
or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of
the Content.
This article may be used for research, teaching, and private study purposes. Any substantial or systematic
reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any
form to anyone is expressly forbidden. Terms & Conditions of access and use can be found at http://
www.tandfonline.com/page/terms-and-conditions

Supramolecular Chemistry
Vol. 23, No. 5, May 2011, 407–410
An ion-responsive fluorescent compound based on NO-photoisomerisation styryl derivative
linked to monoaza-15-crown-5
Jing Caoab*, Jun Xiang Fenga, Yong Xiang Wua, Xue Qun Peia, Jiao Jiao Yana, Yang Liua,
Wen Jie Qina and Xiao Bin Zhanga
b
aCollege of Chemistry, Xiangtan University, Xiangtan, Hunan 411105, P.R. China; Key Laboratory of Environmentally Friendly
Chemistry and Application of Ministry of Education, College of Chemistry, Xiangtan University, Xiangtan, Hunan 411105, P.R. China
(Received 1 May 2010; final version received 10 October 2010)
A novel 15-aza-5-crown ether linked to styryl chemosensory 13-(4-((9H-fluoren-9-ylidene)methyl)-2-nitrophenyl)-
1,4,7,10-tetraoxa-13-azacyclopentadecane was designed and synthesised, it would not occur during photoisomerisation
under radiation of light but shows special capability of selectively recognising for Sr2þ
.
Keywords: 15-aza-5-crown ether; photoisomerisation; Sr2þ; fluorescent enhancement
Introduction
hexamethylphosphamide media afforded 2 (12), and then
it reacted with triphenylphosphoniumfluorenylide to give
the target product chemosensory FMN-crown (13).
In the case of a molecule containing a double bond,
e.g. WXCvCYZ (W, X, Y, Z are substituting groups on
the double bond), isomerisation will not exist where
WvX or YvZ (14); therefore, FMN-crown does not give
isomers. The experiment demonstrates that FMN-crown is
so stable in solution that repetitive absorption spectra show
no change under ambient light for 4 weeks. Instead, the
literature reported that some of the styryl compounds were
linked to azacrown as given in Scheme 1, which show a
partial conversion of the trans isomer into the cis isomer in
a short period (15).
Thephotophysicsandphotochemistryoffluorophoreslinked
to crown ethers or involved in complexing supramolecular
structures are the areas of growing interest (1–3). Styryl
compounds linked to azacrown ether yield molecular
systems, where styryl moiety can provide the chromo- and
fluorogenic properties. A lot of these styryl derivatives have
been developed since several decades (Scheme 1), they were
reported to have high fluorescence quantum efficiency and
selectivity for the divalent alkaline earths, particularly Ca2þ
(4–10). It is well known that stilbene would occur during
trans–cis isomerisation under the radiation of light, because
the torsion of double bond becomes easy in the excited state
(11). Although introducing substituting groups on aromatic
ring of stilbene may increase the torsional barrier of double
bond, trans–cis photoisomerisation is still inevitable.
Photophysical properties of fluorophore will be worst
affected by the photoisomerisation in the styryl compounds
containing azacrown group. This led us to synthesise a new
styryl molecule 13-(4-((9H-fluoren-9-ylidene)methyl)-2-
nitrophenyl)-1,4,7,10-tetraoxa-13-azacyclopentadecane
(FMN-crown) with the aim at avoiding photoisomerisation.
Herein, we report the preparation and spectroscopic study of
this novel chemosensory.
FMN-crown exhibits weak emission in acetonitrile as
that of model compound 1a in acetonitrile solution
(Figure 1), which should be attributed to repulsion
between benzene and fluorene. As we know, trans-stilbene
shows strong emission in solution, whereas cis-stilbene
shows almost no fluorescence emission, since a steric
repulsion between two benzene moieties in the cis-stilbene
molecule reduces conjugation of the system (11). A
dihedral angle of the benzene and fluorene plane in model
molecule 1a was 418 through analysing on the Chem3D
Ultra 10.0 program (Figure 2).
We have found thatthe FMN-crown strongly respondsto
certain metal cations. As shown in Figure 3, the 2.1-mM
FMN-crown in acetonitrile undergoes an increase in
quantum efficiency when complexed with some of the
divalent cations. Consequently, the FMN-crown ether is
Results and discussion
The synthetic route for fluorescent sensor FMN-crown is
depicted in Scheme 2. Our synthesis began with 4-
chlorobenzaldehyde, which produced 4-chloro-3-nitro-
benzaldehye in the presence of HNO3 and H2SO4. Pd-
catalysed coupling reaction of 3 with aza-15-crown-5 in
found to be optically responsive to Naþ, Kþ, Mg2þ, Ca2þ
Sr2þ, Cd2þ, Pb2þ and Cu2þ, which could also be observed
,
*Corresponding author. Email: caojing8088@xtu.edu.cn
ISSN 1061-0278 print/ISSN 1029-0478 online
q 2011 Taylor & Francis
DOI: 10.1080/10610278.2010.532215
http://www.informaworld.com

408
J. Cao et al.
Me
Me
10
8
O
O
N
N
(S1)
(S2)
(S4)
O
O
Me
Me
1
Me
H
N
N
O
(S5)
(S6)
N
O
N
Me
O
NC CN
1a
N
(S3)
6
+
N Me
O
Me
4
Scheme 1. Reported styryl compounds with aza-15-crown-5
group.
2
from the absorption spectra of FMN-crown (2.1 £ 10–5 M)
in acetonitrile at room temperature upon the addition of 50
equiv. of various metal cations (Figure 4).
0
400
450
500
550
600
650
Unlike some styryl compounds linked to azacrown, i.e.
compound S3 in Scheme 1 (8), the emission of the FMN-
crown is not quenched upon complexation. The observed
variationsintheFMN-crownemissionspectrumwithcations
are believed to be due to the hindering process of
photoinduced electron transfer between the aza group and
fluorophore; complexation by cations reduces nitrogen atom
donor character and thus hinders electron transfer (16).
Sr2þ is particularly reactive with the FMN-crown and
causes a great increase in the fluorescence intensity. The
Wavelength (nm)
Figure 1. Fluorescence spectra of compound 1 and model
compound 1a (2.1 £ 10–6 M) in acetonitrile at room temperature.
Ks with correlation coefficients better than 0.98, and Ks for
Sr2þ is up to 1.6 £ 103.
Conclusion
other cations cause significantly smaller change than Sr2þ
.
In conclusion, FMN-crown was designed to avoid
photoisomerisation, by an appropriate introduction of the
combination of fluorene group and carbon–carbon double
bond. The novel crown ether exhibits high response ability
for Sr2þ. Our further efforts will specifically elucidate the
role of the nitro group in the photochemical behaviour of
this stilbene-like molecule and develop new fluorescent
chemosensory, molecular switches, photo devices and
other photo-active materials.
Closely matching the crown cavity in size, Ca2þ has been
previously shown to complex strongly with the aza-15-
crown-5, binding with the lone pair of the macrocycle’s
aza group, creating the largest intensity change in the
fluorescence emission peak of the alkaline earths (17).
However, FMN-crown shows less sensitivity to Ca2þ and
causes slightly change in the emission spectra. The nitro
group on benzene near to crown ether is thought to have an
effect on the complexation of azacrown with metal cations.
Fluorometric titrations were carried out by the addition
of known quantities of metal cations to 2.1 £ 10–6 M
solution of free ligand. Titration of Sr2þ into acetonitrile
solution of FMN-crown gave a concomitant enhancement
of the fluorescence intensity (Figure 5). The monotonous
dependence indicates a 1:1 stoichiometry within the
concentration range investigated. The stability constant Ks
was determined with linear least square analysis of Io/(I–
Io) vs. 1/[M] (18). The intercept/slope of the plot provided
Experimental
Reagents
The solvents and the reagents used in the synthesis of
chemosensory 1 were purchased from Aladdin Reagent
Company (Shanghai, China) and used without further
purification. Analytical grade inorganic salts NaClO4,
KClO4, MgCl2, CaCl2, SrCl2·6H2O, CuSO4·5H2O,
O2N
41.4
aza-15-crown-5
HNO3,H2SO4
Cl
CHO
Cl
CHO
3
O2N
O2N
O
O
O
O
O
PPh3
N
CHO
N
O
O
O
2
1
Figure 2. Dihedral angle of benzene and fluorene plane in
model molecule 1a through analysing on Chem3D Ultra 10.0
program.
Scheme 2. Synthetic routes for chemosensory 1.

Supramolecular Chemistry
409
160
140
120
100
80
1.0
0.8
0.6
0.4
0.2
0.0
100
80
60
40
20
0
100 eq
0
10000 20000 30000 40000 50000
1/[M]
50 eq
60
20 eq
10 eq
40
Free
20
Mg2+ Ca2+ K+ Na+ Cu2+ Mn2+ Cd2+ Pb2+ Sr2+
0
400
450
500
550
Wavelength (nm)
600
650
700
Figure 3. Fluorescence enhancement of compound
1
(2.1 £ 10–6 M) in acetonitrile at room temperature upon
addition of various metal cations; excitation at 378 nm; metal
cations, 50 equiv. IF is the fluorescence intensity of 1 with metal
cations; I0 is the fluorescence intensity of free 1.
Figure 5. Titration profiles for fluorescence emission spectra of
FMN-crown (2.1 £ 10–6 M) with Sr2þ in acetonitrile.
and 100 ml metal ion aqueous solutions (2.1 £ 10–6 M) to
5 ml acetonitrile solution of compound 1 (2.1 £ 10–6 M),
respectively.
MnSO4, CdCl2 and Pb(NO3)2 were also purchased from
this company.
Absorbance and fluorescence titrations
Synthetic procedures and physical data
Absorption spectra were recorded on a Lambda 25
spectrophotometer under the control of a Pentium PC
running the manufacturer-supplied software package.
Fluorescence spectra were obtained on a Perkin-Elmer
LS55 luminescence spectrometer with 10nm excitation and
emission slit widths, excitation at 378 nm. All solutions of
fluorescent chemosensory 1 were prepared in spectroscopic
grade acetonitrile without special efforts to exclude water or
air. Fluorescence titrations were carried out with 10, 20, 50
Processfor preparationof4-chloro-3-nitrobenzaldehyde(3)
4-Chlorobenzaldehyde (0.10 mol) was added for 20 min to
a stirred mixture of HNO3 (10.0 ml) and concentrated
sulphuric acid (120 ml) in an ice bath. After 3 h of stirring
at room temperature, the solution was poured onto ice
(400 ml) and then precipitate was collected by filtration,
washed with H2O and dried on vacuum. The crude product
was recrystallised from hexane to afford 4-chloro-3-
1
nitrobenzaldehyde. Yield 45%, mp 61–628C. H NMR
(CDCl3) d 10.06 (s, 1 H), 8.38 (s, 1 H), 8.05 (d, 1 H), 7.78
(d, 1 H). 13C NMR (CDCl3) d 188.4, 135.4, 133.1, 133.0,
132.7, 126.3. Anal. Calcd for C7H4ClNO3: C, 45.31; H,
2.17; N, 7.55. Found C, 45.38; H, 2.32; N, 7.75.
Sr2+
Cu2+
0.6
Ca2+
Mn2+
0.5
Mg2+
Free
Cd2+
Process for preparation of 3-nitro-4-(1,4,7,10-tetraoxa-
13-azacyclopentadecan-13-yl)benzaldehyde (2)
0.4
K+
Na+
0.3
0.2
To a stirred hexamethylphosphoramide solution of 4-chloro-
3-nitrobenzaldehyde (0.2g, 1.10mmol), Pd (CH3COO)2
(10 mg) and o-phenanthroline (11 mg) were added, aza-15-
crown-5(0.24 g, 1.10mmol) was slowlydropped inunderN2
protection. The reaction mixture was immersed in 808C oil
bath and stirred at this temperature for 24h. After cooling to
room temperature, the reaction mixture was diluted with
20ml CH2Cl2, washed with water, dried over Na2SO4 and
the solvent was removed on vacuum. The residue was
purified by chromatography on silica gel, eluting with
EtOAc–petroleum ether (1:1), to afford yellow oil product 2.
Yield 52%. 1H NMR (CDCl3) d 9.89 (s, 1 H), 8.15 (s, 1 H),
Pb2+
0.1
0.0
200
300
400
500
600
700
800
Wavelength (nm)
Figure 4. Absorption spectra of compound 1 (2.1 £ 10–5 M) in
acetonitrile at room temperature upon addition of 50 equiv. of
various metal cations.

410
J. Cao et al.
7.88 (m, 1 H), 7.35 (m, 1 H), 3.75 (m, 4 H), 3.62 (m, 16 H).
13C NMR (CDCl3) d 188.7, 148.2, 139.2, 132.3, 129.9,
126.5, 117.6, 71.1, 70.5, 70.3, 68.7, 53.4. Calcd for
C17H24N2O7: C, 55.43; H, 6.57; N, 7.60. Found C, 55.48;
H, 6.72; N, 7.67.
References
(1) (a) McDonagh, C.; Burke, C.S.; MacCraith, B.D. Chem.
Rev. 2008, 108, 400–422. (b) Valeur, B.; Leray, I. Coord.
Chem. Rev. 2000, 205, 3–40.
(2) Jiang, P.J.; Guo, Z.J. Coord. Chem. Rev. 2004, 248,
205–229.
(3) Wang, H.H.; Xue, L.; Qian, Y.Y.; Jiang, H. Org. Lett. 2010,
12, 292–295.
(4) Martin, M.M.; Plaza, P.; Dai, N.H.; Meyer, Y.H.; Bourson, J.;
Valeur, B. Chem. Phys. Lett. 1993, 202, 425–430.
(5) Martin, M.M.; Plaza, P.; Meyer, Y.H.; Begin, L.; Bourson, J.;
Valeur, B. J. Fluoresc. 1994, 4, 271–275.
Process for preparation of FMN-crown,1
Toa solutionoftriphenylphosphoniumfluorenylide(0.188g,
0.43mmol) in 5 ml of chloroform compound 2 was added
(0.160g, 0.43mmol). After heating the orange solution
under reflux for 3 h, the solvent was evaporated on the steam
bath. The residual oil was purified by chromatography on
silica gel, eluting with EtOAc–petroleum ether (1:1), to
afford orange oil product 1. Yield 45%. 1H NMR (CDCl3) d
7.71–7.94 (m, 12 H), 3.61–3.77 (m, 20 H). 13C NMR
(CDCl3) d 144.0, 141.7, 141.4, 139.4, 139.1, 136.7, 136.1,
133.9, 128.8, 128.3, 128.1, 127.1, 126.9, 126.8, 124.5, 124.0,
122.0, 120.2, 119.9, 119.6, 71.1, 70.6, 70.5, 69.4, 53.6. Calcd
for C30H32N2O6: C, 69.75; H, 6.24; N, 5.42. Found C, 69.88;
H, 6.51; N, 5.47; m/z: 516.4.
´
(6) Delmond, S.; Letard, J.F.; Lapouyade, R.; Mathevet, R.;
Jonusauskas, G.; Rulliere, C. New J. Chem. 1996, 20,
`
861–865.
(7) Fery-Forgues, R.; Le Bris, M.T.; Guette, J.P.; Valeur, B.
J. Chem. Soc. Chem. Commun. 1988, 5, 384–385.
(8) Cazaux, L.; Faher, M.; Lopez, A.; Picard, C.; Tisnes, P.
J. Photochem. Photobiol. A: Chem. 1994, 77, 217–225.
(9) Ahmad, A.R.; Mehta, L.K.; Parrick, J. Tetrahedron 1995,
51, 12899–12910.
(10) Thomas, K.J.; Manojkumar, T.K.; Das, S.; George, M.V.
Proc. Indian Acad. Sci. (Chem. Sci.) 1994, 106,
1375–1378.
(11) Waldeck, D.H. Chem. Rev. 1991, 91, 415–436.
(12) Cao, J.; Feng, J.X.; Wu, Y.X.; Tuo, Y.Y. Chin. Chem. Lett.
2010, 21, 935–938.
(13) William, J.A. J. Org. Chem. 1959, 24, 282–284.
(14) March, J. Advanced Organic Chemistry, 2nd ed.; McGraw-
Hill Book Company: New York, 1977, 345–346.
(15) Drake, J.M.; Lesiecki, M.L.; Camaioni, D.M. Chem. Phys.
Lett. 1985, 113, 530–534.
Acknowledgements
We thank for financial support by the open project programme of
Key Laboratory of Environmentally Friendly Chemistry and
Applications of Ministry of Education, China (No. 09HJYH04);
Hunan Science and Technology Department Project (No.
2009FJ3166) and Hunan Province Undergraduates Innovating
Experimentation Project (2009).
(16) Valeur, B. Molecular Fluorescence: Principles and
Applications; Wiley: New York, 2001, 292–293.
(17) Bourson, J.; Valeur, B. J. Phys. Chem. 1989, 93,
3871–3876.
(18) Connors, K.A. Binding Constants; Wiley: New York, 1987,
171–373.