The synthesis and fluorescence properties of novel chromenone-crown ethers

Article abstract of DOI:10.1080/10610278.2010.483737

o-Dihyroxy-3-phenylchromenone derivatives, namely, 6,7-dihydroxy-3-(3',4'- dimethoxyphenyl)chromenone and 6,7-dimethoxy-3-(3',4'-dihydroxyphenyl) chromenone, were obtained from 2,4,5-trihydroxybenzaldehyde/3,4- dimethoxyphenylacetic acid and 2-hydroxy-4,5-dimethoxybenzaldehyde/3,4- dihydroxyphenylacetic acid, respectively, in the presence of acetic anhydride and sodium acetate under an inert atmosphere, after treatment with MeOH/HCl(aq). The chromenone-crown ethers were prepared from cyclic condensation of o-dihydroxy-3-phenylchromenones with poly(ethylene glycol) ditosylates in the presence of CH3CN/alkali metal carbonates. The chromatographically purified novel chromenone-crown ethers were identified by 1H NMR, MALDI-TOF mass spectrometry and elemental analysis. The fluorescence and UV-vis spectroscopic properties of the obtained chromenone-crown ethers and their complexes with Li⁺, Na⁺ and K⁺ perchlorate salts were estimated in acetonitrile. The quantum yields of novel chromenone-crown ethers were determined by the comparative method.

Full text of DOI:10.1080/10610278.2010.483737

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The synthesis and fluorescence properties of novel
chromenone-crown ethers
Cihan Gündüz a , Ümit Salan a & Mustafa Bulut a
a Department of Chemistry , Marmara University , 34722, Kadikoy, Istanbul, Turkey
Published online: 07 Jun 2010.
To cite this article: Cihan Gündüz , Ümit Salan & Mustafa Bulut (2010) The synthesis and fluorescence properties of novel
chromenone-crown ethers, Supramolecular Chemistry, 22:9, 491-498, DOI: 10.1080/10610278.2010.483737
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Supramolecular Chemistry
Vol. 22, No. 9, September 2010, 491–498
The synthesis and fluorescence properties of novel chromenone-crown ethers
¨
Cihan Gu¨ndu¨z, Umit Salan and Mustafa Bulut*
Department of Chemistry, Marmara University, 34722 Kadikoy, Istanbul, Turkey
(Received 21 December 2009; final version received 5 April 2010)
o-Dihyroxy-3-phenylchromenone derivatives, namely, 6,7-dihydroxy-3-(30,40-dimethoxyphenyl)chromenone and 6,7-
dimethoxy-3-(30,40-dihydroxyphenyl)chromenone, were obtained from 2,4,5-trihydroxybenzaldehyde/3,4-dimethoxyphe-
nylacetic acid and 2-hydroxy-4,5-dimethoxybenzaldehyde/3,4-dihydroxyphenylacetic acid, respectively, in the presence of
acetic anhydride and sodium acetate under an inert atmosphere, after treatment with MeOH/HCl(aq). The chromenone-
crown ethers were prepared from cyclic condensation of o-dihydroxy-3-phenylchromenones with poly(ethylene glycol)
ditosylates in the presence of CH3CN/alkali metal carbonates. The chromatographically purified novel chromenone-crown
ethers were identified by 1H NMR, MALDI-TOF mass spectrometry and elemental analysis. The fluorescence and UV–vis
spectroscopic properties of the obtained chromenone-crown ethers and their complexes with Liþ, Naþ and Kþ perchlorate
salts were estimated in acetonitrile. The quantum yields of novel chromenone-crown ethers were determined by the
comparative method.
Keywords: chromenone-crown ethers; 3-phenylchromenone; quantum yield; synthesis; cation binding
Introduction
We now reportonthe synthesis (Scheme 1), spectral data
and quantum yields of new 12-crown-4, 15-crown-5 and 18-
crown-6 derivatives of o-dihydroxy-3-phenylchromenone
and their complexes with Liþ, Naþ and Kþ perchlorate salts
using fluorescence spectroscopy (Table 1).
Pedersen (1) has shown that crown ethers have remarkable
binding properties for specific metal cations. Generally,
crown ethers selectively display a stable complex with
metal cations which best matches the cavity; however,
selectivity and stability depend on solvent properties (2).
Much of the research involving crown ethers has focused
on metal ion selectivity for the development of optical
sensors due to their sensitivity and reactivity in the
presence of metal cations (3). Crown ethers are commonly
used to bind cations, catalyse phase-transfer reactions (4),
as colorimetric reagents (5), in chromatographic separ-
ations (6) and for the photometric determination of metal
cations (7). Spectrofluorometry is a very sensitive
technique that measures both emission and excitation
intensities of a fluorescent molecule, which is usually
influenced by the characteristics of the environment and
small changes in the positions of the energetic levels that
determine the quantum yield and fluorescence decay (8).
Chromenone-crown ethers have been used in metal ion
detection (9–11). We have synthesised fluorogenic
chromenone-crown ether derivatives of 12-crown-4, 15-
crown-5 and 18-crown-6, and have examined their cation-
binding effects in acetonitrile using steady-state fluor-
escence spectroscopy (11–14), conductometry (15, 16)
and extraction (17).
Experimental
General
The starting chemicals, 2,4,5-trimethoxybenzaldehyde,
3,4-dihydroxyphenylacetic acid and 3,4-dimethoxyphe-
nylacetonitrile, were purchased from Acros (Geel,
Belgium), Aldrich (St Louis, MO, USA) or Merck
(Darmstadt, Germany), unless otherwise cited. Melting
points were obtained on a Gallenkamp apparatus. 1H
NMR spectra were determined by a Brucker DPX-400,
400 MHz high-performance digital FT-NMR spec-
trometer. Mass spectra were obtained with a MALDI-
TOF instrument, model Bruker Autoflex III. Elemental
analyses were performed on a LECO CHNS 92
instrument. UV–vis and fluorescence spectra were
obtained on an Agilent 8453 model UV–vis and a
Hitachi F-7000 fluorescence spectrophotometer, respect-
ively. All spectrophotometric measurements were carried
out at 208C. Fluorescence quantum yields (FF) were
determined by the comparative method with quinine
sulphate as the standard (18–20).
*Corresponding author. Email: mbulut@marmara.edu.tr
ISSN 1061-0278 print/ISSN 1029-0478 online
q 2010 Taylor & Francis
DOI: 10.1080/10610278.2010.483737
http://www.informaworld.com

¨ ¨
C. Gunduz et al.
492
Table 1. Absorption, excitation, emission wavelengths (nm),
Stokes’ shifts (nm) and quantum yields of chromenone-crown
ethers in CH3CN at 208C.
H3CO
H3CO
OCH3
CHO
1
Complexes
BBr3 / CH2Cl2
Dry ice / acetone
Compound
Ligand
Liþ
Naþ
Kþ
6a
H3CO
H3CO
OH
HO
HO
OH
labsorption (nm)
lexcitation (nm)
362
370
457
95
360
370
456
96
361
370
456
95
362
370
457
95
CHO
CHO
l
emission (nm)
Stokes (nm)
FF
6b
2b
2a
D
+
+
0.45
0.38
0.30
0.41
HO
HO
OH
H3CO
H3CO
OH
l
absorption (nm)
lexcitation (nm)
emission (nm)
Stokes (nm)
FF
367
371
461
94
366
371
461
95
367
371
462
95
366
371
460
94
O
O
3a
3b
l
D
Ac2O / AcONa
0.58
0.36
0.47
0.34
N2 , 160°C
6c
labsorption (nm)
lexcitation (nm)
367
371
461
94
367
371
459
92
367
371
460
93
367
371
459
92
l
emission (nm)
Stokes (nm)
FF
6d
H3CO
H3CO
O O
D
OAc
OAc
AcO
AcO
O O
0.52
0.52
0.39
0.53
OCH3
OCH3
l
absorption (nm)
lexcitation (nm)
emission (nm)
Stokes (nm)
FF
359
367
466
107
0.24
360
367
466
106
0.32
357
367
466
109
0.30
357
367
466
109
0.31
4a
4b
l
D
MeOH / HCl
N2 , reflux
6e
6f
labsorption (nm)
lexcitation (nm)
368
371
463
95
368
371
463
95
367
371
463
96
367
371
462
95
1
O
8
5
7
6
H3CO
H3CO
2 O
HO
HO
O
O
2'
5'
3
l
emission (nm)
Stokes (nm)
FF
3' OH
OCH3
OCH3
1'
4
D
4'
6'
OH
0.30
0.37
0.31
0.42
5a
5b
labsorption (nm)
lexcitation (nm)
368
371
462
94
367
371
462
95
367
371
463
96
367
371
463
96
Me2CO3 / CH3CN
N2 , reflux
l
emission (nm)
Stokes (nm)
FF
D
0.61
0.46
0.35
0.47
TsO
O
O
n O OTs
n : 0,1,2
H3CO
H3CO
O
O
nO
O
O
O
O
O
solution was added. The mixture was extracted with
CH2Cl2 (3 £ 100 ml). The organic layers were washed
with NaCl solution (2 £ 100 ml) and water (100 ml). The
product was dried over Na2SO4 and evaporated to
produce 2a (4.3 g, 91%). Mp 103–1048C (lit. 1048C
(21)). MS (MALDI-TOF): m/z ¼ 182.6 [M]þ. C9H10O4
(182.06).
n
O
O
O
O
O
O
OCH3
OCH3
6a-c
6d-f
Scheme 1. Synthesis of chromenone-crown ethers.
Synthesis
Synthesis of 2-hydroxy-4,5-dimethoxybenzaldehyde (2a)
General procedure for the synthesis of o-diacetoxy-3-
phenylchromenones (4a and 4b)
Boron tribromide (5.0 g, 20 mmol) was slowly added to a
stirring solution of 2,4,5-trimethoxybenzaldehyde (5.0 g,
25 mmol) in CH2Cl2 in a dry ice/acetone bath. After 1 h,
the reaction mixture was warmed to room temperature
and stirred for 3 h, and then a HCl (10%; 20 ml) aqueous
In a typical reaction, a mixture of benzaldehyde (2a and
2b) (20 mmol), phenylacetic acids (3a and 3b) (20 mmol)
and sodium acetate (50 mmol) was stirred in acetic
anhydride (40 ml) at 1608C under N2 atmosphere for 6 h.

Supramolecular Chemistry
493
The reaction mixture was cooled, poured into ice-cold
water (200 ml) and then filtered. The crude products were
purified via crystallisation from ethanol.
Synthesis of 6,7-dihydroxy-3-(30,40-
dimethoxyphenyl)chromenone (5b; C17H14O6)
Compound 4b (4.7 g, 12 mmol) was treated as described
above to yield 5b (3.1 g, 82%). Mp 255–2568C. 1H NMR
(400 MHz, CD3OD, 258C): d ¼ 3.86 (s, 3H, OCH3), 3.87
(s, 3H, OCH3), 6.77 (s, 1H), 6.98 (d, J ¼ 8.9 Hz, 1H), 7.0
(s, 1H), 7.26 (dd, J ¼ 8.4, 2 Hz, 1H), 7.32 (d, J ¼ 2 Hz,
1H) and 7.89 (s, 1H) ppm. MS (MALDI-TOF):
m/z ¼ 314.7 [M]þ. C17H14O6 (314.08).
Synthesis of 6,7-dimethoxy-3-(30,40-
diacetoxyphenyl)chromenone (4a; C21H18O8)
The mixture of 2-hydroxy-4,5-dimethoxybenzaldehyde
(2a) (3.6 g, 20 mmol), 3,4-dihydroxyphenylacetic acid
(3a) (3.4 g, 20 mmol) and sodium acetate (4.1 g,
50 mmol) in acetic anhydride (40 ml) was treated as
described above to yield 4a (7.7 g, 97%). Mp 207–
General procedure for the synthesis of 3-
phenylchromenone-crown ethers (6a–6f)
1
2088C. H NMR (400 MHz, CDCl3, 258C): d ¼ 2.31 (s,
6H, COCH3), 3.93 (s, 3H, OCH3), 3.96 (s, 3H, OCH3),
6.87 (s, 1H), 6.91 (s, 1H), 7.26 (d, J ¼ 8.2 Hz, 1H), 7.61
(dd, J ¼ 8.2, 2 Hz, 1H), 7.63 (d, J ¼ 2 Hz, 1H) and 7.77
(s, 1H) ppm. MS (MALDI-TOF): m/z ¼ 398.9 [M]þ.
C21H18O8 (398.10).
The typical procedure for the cyclisation reaction leading
to macrocycle ethers (6a–6f) is as follows. A mixture of o-
dihydroxy-3-phenylchromenones (5a and 5b) (3 mmol),
poly(ethylene glycol) ditosylate (3 mmol) and alkali metal
carbonate (6 mmol) was dissolved in CH3CN (60 ml). The
mixture was heated for 35–40 h at 80–858C. The solvent
was evaporated in vacuo. Diluted HCl was added to the
residue and the mixture was extracted with CHCl3
(4 £ 50 ml). The combined organic layers were washed
with water, dried over CaCl2 and evaporated in vacuo.
Chromatography of the crude products (silica gel 60,
Merck) with chloroform gave pure chromenone-crown
ethers (6a–6f).
Synthesis of 6,7-diacetoxy-3-(30,40-
dimethoxyphenyl)chromenone (4b; C21H18O8)
The mixture of 2,4,5-trihydroxybenzaldehyde (2b) (3.0 g,
20 mmol), 3,4-dimethoxyphenylacetic acid (3b) (3.9 g,
20 mmol) and sodium acetate (4.1 g, 50 mmol) in acetic
anhydride (40 ml) was treated as described above to
1
produce 4b (4.8 g, 60%). Mp 2208C. H NMR (400 MHz,
CD3OD, 258C): d ¼ 2.33 (s, 3H, COCH3), 2.34 (s, 3H,
COCH3), 3.93 (s, 3H, OCH3), 3.95 (s, 3H, OCH3), 6.94 (d,
J ¼ 8.2 Hz, 1H), 7.25 (dd, J ¼ 8.2, 2.3 Hz, 1H), 7.27 (d,
J ¼ 2.3 Hz, 1H), 7.28 (s, 1H), 7.39 (s, 1H) and 7.71 (s, 1H)
ppm. MS (MALDI-TOF): m/z ¼ 397.8 [M]þ. C21H18O8
(398.10).
6,7-Dimethoxy-3-(2,3,5,6,8,9-hexahydrobenzo[b][1,4,7,
10]tetraoxacyclododecin-12-yl)-2H-chromen-2-one (6a;
C23H24O8)
The mixture of compound 5a (1.0 g, 3.2 mmol), Na2CO3
(0.7 g, 6.4 mmol) and tri(ethylene glycol) ditosylate (1.5 g,
3.2 mmol) in CH3CN (60 ml) was reacted as described
1
above to produce 6a (0.21 g, 15%). Mp 178–1798C. H
NMR (400 MHz, CDCl3, 258C): d ¼ 3.69 (t, J ¼ 4 Hz,
4H), 3.80 (s, 6H, OCH3), 3.96 (t, J ¼ 4 Hz, 4H), 4.20 (t,
J ¼ 4 Hz, 4H), 6.88 (s, 1H), 6.90 (s, 1H), 6.93 (d,
J ¼ 8.2 Hz, 1H), 7.28 (dd, J ¼ 8.2, 2.3 Hz, 1H), 7.31 (d,
J ¼ 2.3 Hz, 1H) and 7.70 (s, 1H) ppm. MS (MALDI-
TOF): m/z ¼ 427.9 [M]þ, 450.9 [M þ Na]þ. C23H24O8
(428.15): calcd C ¼ 64.48, H ¼ 5.65; found C ¼ 64.37,
H ¼ 5.54.
General procedure for the synthesis of o-dihydroxy-3-
phenylchromenones (5a and 5b)
The o-diacetoxy-3-phenylchromenone derivatives (4a and
4b) were refluxed with MeOH/HCl(aq) for 3 h, methanol
was removed using distillation and the precipitates were
collected by filtration. The crude products were purified by
crystallisation from ethanol.
Synthesis of 6,7-dimethoxy-3-(30,40-
dihydroxyphenyl)chromenone (5a; C17H14O6)
6,7-Dimethoxy-3-(2,3,5,6,8,9,11,12-octahydrobenzo[b][1,
4,7,10,13]pentaoxacyclopentadecin-15-yl)-2H-chromen-
2-one (6b; C25H28O9)
Compound 4a (6.4 g, 16 mmol) was treated as described
above to yield 5a (3.2 g, 64%). Mp 220–2218C. 1H NMR
(400 MHz, CD3OD, 258C): d ¼ 3.79 (s, 3H, OCH3), 3.81
(s, 3H, OCH3), 6.74 (d, J ¼ 8.4 Hz, 1H), 6.78 (s, 1H), 6.90
(dd, J ¼ 8.2, 1.8 Hz, 1H), 7.10 (d, J ¼ 1.8 Hz, 1H), 7.15 (s,
1H) and 7.58 (s, 1H) ppm. MS (MALDI-TOF):
m/z ¼ 314.7 [M]þ. C17H14O6 (314.08).
The mixture of compound 5a (1.0 g, 3.2 mmol), Na2CO3
(0.7 g, 6.4 mmol) and tetra(ethylene glycol) ditosylate
(1.6 g, 3.2 mmol) in CH3CN (60 ml) was reacted as
described above to produce 6b (0.31 g, 20%). Mp 161–
1
1628C. H NMR (400 MHz, CDCl3, 258C): d ¼ 3.69 (t,
J ¼ 4 Hz, 4H), 3.77 (t, J ¼ 4 Hz, 4H), 3.81 (s, 6H, OCH3),

¨ ¨
C. Gunduz et al.
494
3.96 (t, J ¼ 5 Hz, 4H), 4.20 (t, J ¼ 5 Hz, 4H), 6.87 (s, 1H),
6.90 (s, 1H), 6.93 (d, J ¼ 8.9 Hz, 1H), 7.28 (dd, J ¼ 8.9,
2.3 Hz, 1H), 7.31 (d, J ¼ 2.3 Hz, 1H) and 7.70 (s, 1H)
ppm. MS (MALDI-TOF): m/z ¼ 495.0 [M þ Na]þ.
C25H28O9 (472.17): calcd C ¼ 63.55, H ¼ 5.97; found
C ¼ 63.44, H ¼ 5.86.
J ¼ 2.3 Hz, 1H) and 7.68 (s, 1H) ppm. MS (MALDI-
TOF): m/z ¼ 495.0 [M þ Na]þ. C25H28O9 (472.17): calcd
C ¼ 63.55, H ¼ 5.97; found C ¼ 63.64, H ¼ 5.88.
20-(3,4-Dimethoxyphenyl)-5,6,8,9,11,12,14,15-
octahydro-2H-[1,4,7,10,13,16]hexaoxacyclooctadeca[2,
3-g]chromen-19(3H)-one (6f; C27H32O10)
6,7-Dimethoxy-3-(2,3,5,6,8,9,11,12,14,15-
decahydrobenzo[b][1,4,7,10,13,16]hexaoxacyclo
octadecin-18-yl)-2H-chromen-2-one (6c; C27H32O10)
The mixture of compound 5b (1.0 g, 3.2 mmol), K2CO3
(0.9 g, 6.4 mmol) and penta(ethylene glycol) ditosylate
(1.7 g, 3.2 mmol) in CH3CN (60 ml) was reacted as
described above to produce 6f (0.36 g, 22%). Mp 148–
The mixture of compound 5a (1.0 g, 3.2 mmol), K2CO3
(0.9 g, 6.4 mmol) and penta(ethylene glycol) ditosylate
(1.7 g, 3.2 mmol) in CH3CN (60 ml) was reacted as
described above to produce 6c (0.26 g, 16%). Mp 122–
1
1498C. H NMR (400 MHz, CDCl3, 258C): d ¼ 3.77 (t,
J ¼ 4 Hz, 8H), 3.92 (t, J ¼ 4 Hz, 8H), 3.94 (s, 6H, OCH3),
4.22 (t, J ¼ 5 Hz, 4H), 6.85 (s, 1H), 6.92 (d, J ¼ 8.2 Hz,
1H), 7.12 (s, 1H), 7.24 (dd, J ¼ 8.6, 2.3 Hz, 1H), 7.30 (d,
J ¼ 2.3 Hz, 1H) and 7.67 (s, 1H) ppm. MS (MALDI-
TOF): m/z ¼ 517.0 [M]þ, 539.0 [M þ Na]þ. C27H32O10
(516.20): calcd C ¼ 62.78, H ¼ 6.24; found C ¼ 62.64,
H ¼ 6.16.
1
1238C. H NMR (400 MHz, CDCl3, 258C): d ¼ 3.69 (t,
J ¼ 4 Hz, 4H), 3.73 (t, J ¼ 4 Hz, 4H), 3.77 (t, J ¼ 4 Hz,
4H), 3.81 (s, 6H, OCH3), 3.96 (t, J ¼ 4 Hz, 4H), 4.22 (t,
J ¼ 5 Hz, 4H), 6.87 (s, 1H), 6.91 (s, 1H), 6.93 (d,
J ¼ 8.9 Hz, 1H), 7.28 (dd, J ¼ 8.9, 2.3 Hz 1H), 7.31 (d,
J ¼ 2.3 Hz, 1H) and 7.70 (s, 1H) ppm. MS (MALDI-
TOF): m/z ¼ 538.9 [M þ Na]þ, 554.9 [M þ K]þ.
C27H32O10 (516.20): calcd C ¼ 62.78, H ¼ 6.24; found
C ¼ 62.63, H ¼ 6.36.
Results and discussion
The novel chromenone-crown ethers (6a–6f) were
prepared in the presence of CH3CN/metal carbonates
from the cyclic condensation of poly(ethylene glycol)
ditosylates and the corresponding chromenones. The
chromenones, 6,7-dimethoxy-3-(30,40-dihydroxyphenyl)-
chromenone and 6,7-dihydroxy-3-(30,40-dimethoxyphenyl)-
chromenone (5a and 5b), were prepared from 2-hydroxy-
4,5-dimethoxybenzaldehyde/3,4-dihydroxyphenylacetic
acid and 2,4,5-trihydroxy benzaldehyde/3,4-dimethoxyphe-
nylacetic acid, respectively, in the presence of acetic
anhydride and sodium acetate under an inert atmosphere,
after being treated with MeOH/HCl (Scheme 1).
14-(3,4-Dimethoxyphenyl)-5,6,8,9-tetrahydro-2H-[1,4,7,
10]tetraoxacyclododeca[2,3-g]chromen-13(3H)-one (6d;
C23H24O8)
The mixture of compound 5b (1.0 g, 3.2 mmol), Na2CO3
(0.7 g, 6.4 mmol) and tri(ethylene glycol) ditosylate (1.5 g,
3.2 mmol) in CH3CN (60 ml) was reacted as described
1
above to produce 6d (0.31 g, 23%). Mp 182–1838C. H
NMR (400 MHz, CDCl3, 258C): d ¼ 3.77 (t, J ¼ 4 Hz,
4H), 3.92 (t, J ¼ 4 Hz, 4H), 3.94 (s, 6H, OCH3), 4.22 (t,
J ¼ 4 Hz, 4H), 6.89 (s, 1H), 6.93 (d, J ¼ 8.2 Hz, 1H), 7.12
(s, 1H), 7.25 (dd, J ¼ 8.6, 2.3 Hz, 1H), 7.29 (d, J ¼ 2.3 Hz,
1H) and 7.66 (s, 1H) ppm. MS (MALDI-TOF):
m/z ¼ 427.8 [M]þ, 450.8 [M þ Na]þ. C23H24O8
(428.15): calcd C ¼ 64.48, H ¼ 5.65; found C ¼ 64.37,
H ¼ 5.74.
Compounds 5a and 5b were reacted with tri-/tetra- or
penta(ethylene glycol) ditosylate in the presence of
Me2CO3 in CH3CN to produce the chromenone-crown
ethers (6a–6c) and (6d–6f), respectively. Chromato-
graphic separation over a silica gel column eluted with
CHCl3 residue resulted in chromenone-crown ethers 6a–
6f at 15–32% yields. The novel compounds were
17-(3,4-Dimethoxyphenyl)-5,6,8,9,11,12-hexahydro-2H-
[1,4,7,10,13]pentaoxacyclopentadeca[2,3-g]chromen-
16(3H)-one (6e; C25H28O9)
The mixture of compound 5b (1.0 g, 3.2 mmol), Na2CO3
(0.7 g, 6.4 mmol) and tetra(ethylene glycol) ditosylate
(1.6 g, 3.2 mmol) in CH3CN (60 ml) was reacted as
described above to produce 6e (0.48 g, 32%). Mp 164–
1
1658C. H NMR (400 MHz, CDCl3, 258C): d ¼ 3.77 (t,
J ¼ 4 Hz, 8H), 3.92 (t, J ¼ 4 Hz, 4H), 3.94 (s, 6H, OCH3),
4.18 (t, J ¼ 5 Hz, 4H), 6.84 (s, 1H), 6.93 (d, J ¼ 8.2 Hz,
1H), 7.12 (s, 1H), 7.24 (dd, J ¼ 8.6, 2.3 Hz, 1H), 7.30 (d,
Figure 1. Absorption, excitation and emission spectra of the
compound þ6b and its 1:1 complex emission spectra with Liþ,
Naþ and K perchlorate salts in CH3CN.

Supramolecular Chemistry
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800
700
600
500
400
300
200
100
0
400
450
500
550
600
650
nm
Figure 2. The emission spectra of 6a (3 £ 1026 mol/l, top line) depending on LiClO4 concentration increasing from 0 to
2.3 £ 1025 mol/l.
characterised using elemental analysis, 1H NMR and
MALDI-TOF mass spectroscopy.
The fluorescence quantum yields (FF) of the
chromenone-crown ethers were calculated by the
comparative method with the following equation (18–20):
1
The H NMR spectra of 6a–6f showed characteristic
signals for etheral (ZOZCH2ZCH2ZOZ) protons at
d ¼ 3.69–4.22 ppm for each triplet. The peak at d ¼ 3.80–
3.94 ppm indicated the presence of the –OCH3
group. The chemical shifts of the aromatic protons could
be observed at d ¼ 6.84–7.31 ppm. In addition, the
chemical shifts of the coumarin lacton ring proton (H-4)
could be observed at d ¼ 7.68–7.70 ppm. MALDI-TOF
spectrum and elemental analysis confirmed the formation
of chromenone-crown ether derivatives.
ꢀ
ꢁ
2
As Fx hx
FFðxÞ ¼ FFðsÞ
:
Ax Fs hs
Here, subscripts s and x denote the reference and samples,
respectively; FF(x) and FF(s) are quantum yields of the
samples and reference, respectively; Fx and Fs are the areas
under the fluorescence emission curves of the samples and
reference, respectively; Ax and As are the absorbances of
the samples and reference, respectively, at the excitation
1100
1000
900
800
700
600
500
400
300
200
100
0
400
450
500
550
600
650
nm
Figure 3. The emission spectra of 6c (3 £ 1026 mol/l, top line) depending on NaClO4 concentration increasing from 0 to
2.3 £ 1025 mol/l.

¨ ¨
C. Gunduz et al.
496
1100
1000
900
800
700
600
500
400
300
200
100
0
400
450
500
nm
550
600
650
Figure 4. The emission spectra of 6c (3 £ 1026 mol/l, top line) depending on KClO4 concentration increasing from 0 to
2.3 £ 1025 mol/l.
wavelength and hx and hs are the refractive indices of the
solvents used for the samples and reference, respectively.
Quinine sulphate (in 0.5 M H2SO4, FF ¼ 0.546) was used
as a reference for calculating the fluorescence quantum
yields. The absorbance of the solutions at the excitation
wavelength was less than 0.05.
Table 1 shows that larger bathochromic shifts occurred
for the chromenone-crown ethers (6a–6f) and their metal
complexes, as expected. The emission peaks of 6a for Liþ,
Naþ and Kþ complexes were observed at 456 nm in
acetonitrile.
Ligands 6d–6f displayed larger Stokes’ shifts when
compared to 6a–6c. The fluorescence quantum yield (FF)
values of compounds 6a, 6b and 6f with Liþ, Naþ and Kþ
perchlorate salt complexes, respectively, were lower than
those of the ligands in acetonitrile. A comparison of the
FF values for the complexes of compound 6a showed that
the Kþ complex was larger than the Liþ and Naþ
complexes. A similar comparison of FF values for the
Figure 1 depicts the fluorescence emission for
complexes and free ligand, in addition to the excitation
and absorption spectra for compound 6b. Figures 2–7
depict the fluorescence emission spectra for compounds
6a–6f depending on the perchlorate salts. All of the
complexes (6a–6f) demonstrated similar fluorescence
behaviour in acetonitrile.
1000
900
800
700
600
500
400
300
200
100
0
400
450
500
550
600
650
nm
Figure 5. The emission spectra of 6d (3 £ 1026 mol/l, top line) depending on NaClO4 concentration increasing from 0 to
2.3 £ 1025 mol/l.

Supramolecular Chemistry
497
1200
1100
1000
900
800
700
600
500
400
300
200
100
0
400
450
500
550
600
650
nm
Figure 6. The emission spectra of 6e (3 £ 1026 mol/l, top line) depending on NaClO4 concentration increasing from 0 to
2.3 £ 1025 mol/l.
1500
1400
1300
1200
1100
1000
900
800
700
600
500
400
300
200
100
0
400
450
500
550
600
650
nm
Figure 7. The emission spectra of 6f (3 £ 1026 mol/l, top line) depending on KClO4 concentration increasing from 0 to
2.3 £ 1025 mol/l.
complexes of compounds 6b and 6f showed the
relationships Naþ . Liþ . Kþ and Kþ . Liþ . Naþ,
respectively.
These results demonstrate that the binding of such
molecules depends on the structure, crown-ether ring size
and size of the cation radii, which are common for a
macrocyclic effect.
The FF values of the complexes of compound 6c
compared to those of the ligand in acetonitrile showed that
Kþ . 6c ¼ Liþ . Naþ; however, the FF values of the
metal perchlorate salt complexes of compounds 6d and 6e
were higher than those of the ligands in acetonitrile. A
comparison of FF values for the complexes of compounds
6d and 6e showed the relationship Liþ . Kþ . Naþ and
Acknowledgements
We are thankful to the Scientific and Technical Research Council
˙
of Turkey (TUBITAK) [107T347] and the Research Foundation
of Marmara University, Commission of Scientific Research
Project (BAPKO) [FEN-C-DPR-041007-0203].
K
þ . Liþ . Naþ, respectively.

¨ ¨
C. Gunduz et al.
498
¨
(12) Goc¸men, A.; Bulut, M.; Erk, C¸ . Pure Appl. Chem. 1993, 65,
447–450.
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