Convenient syntheses and preliminary photophysical properties of novel 8-aminoquinoline appended diaza-18-crown-6 ligands

Article abstract of DOI:10.1016/S0040-4020(01)00746-3

Novel 7,16-bis(8-amino-2-quinolinylmethyl)- and 7,16-bis(8-amino-7-quinolinylmethyl)-diaza-18-crown-6 ligands (12 and 16) have been synthesized by reductive amination of 8-(di-tert-butoxycarbonyl)amino-2-quinolinecarboxaldehyde (followed by removal of the Boc protecting groups) or 8-amino-7-quinolinecarboxaldehyde with diaza-18-crown-6 using triacetoxyborohydride (NaBH(OAc)₃) as the reducing agent. The crystal structure of ligand 16 is also given. The absorption spectra of 12 and 16 are dominated by two intense bands at 250±5 and 238±1 nm which are blue shifted upon addition of alkaline earth and heavy metal ions in acetonitrile. In addition, intensities of the fluorescence bands of 12 and 16 are reduced in the presence of metal ions.

Full text of DOI:10.1016/S0040-4020(01)00746-3

TETRAHEDRON
Pergamon
Tetrahedron 57 02001) 7623±7628
Convenient syntheses and preliminary photophysical properties of
novel 8-aminoquinoline appended diaza-18-crown-6 ligands
Guoping Xue,a Jerald S. Bradshaw,a,p N. Kent Dalley,a Paul B. Savage,a Krzysztof E. Krakowiak,b
Reed M. Izatt,a Luca Prodi,c Marco Montaltic and Nelsi Zaccheronic
aDepartment of Chemistry and Biochemistry, Brigham Young University, Provo, UT 84602-4678, USA
bIBC Advanced Technologies, Inc., 856 E. Utah Valley Dr., American Fork, UT 84003, USA
cDepartimento di Chimica 'G. Ciamician', Universita di Bologna, Via Selmi 2 I-40126, Italy
Received 8 June 2001
AbstractÐNovel 7,16-bis08-amino-2-quinolinylmethyl)- and 7,16-bis08-amino-7-quinolinylmethyl)-diaza-18-crown-6 ligands 012 and 16)
have been synthesized by reductive amination of 8-0di-tert-butoxycarbonyl)amino-2-quinolinecarboxaldehyde 0followed by removal of the
Boc protecting groups) or 8-amino-7-quinolinecarboxaldehyde with diaza-18-crown-6 using triacetoxyborohydride 0NaBH0OAc)3) as the
reducing agent. The crystal structure of ligand 16 is also given. The absorption spectra of 12 and 16 are dominated by two intense bands at
250^5 and 238^1 nm which are blue shifted upon addition of alkaline earth and heavy metal ions in acetonitrile. In addition, intensities of
the ¯uorescence bands of 12 and 16 are reduced in the presence of metal ions. q 2001 Elsevier Science Ltd. All rights reserved.
1. Introduction
ligands containing two 8-aminoquinoline side arms each
attached through their C-2 012) or C-7 016) positions.
Since the two soft amino donor groups interact strongly
with soft metal ions, we expected these ligands to have
enhanced selectivity toward certain transition and post-
transition metal ions compared to their hydroxyquinoline
analogues 1±3. Also, we expected that the different attach-
ment site of the aminoquinolines to the macrocyclic ligands
will in¯uence metal ion af®nities of the ligands. The X-ray
crystal structure of ligand 16 is also described herein.
Considerable attention has recently been focused on the
development of compounds capable of selectively respond-
ing, via changes in UV absorption or ¯uorescence spectra, to
the presence of speci®c metal ions.1±5 In this context, we
have prepared and studied several series of macrocyclic
ligands with appended chromophores and ¯uorophores for
use as selective metal-ion chemosensors.6±10 8-Hydroxy-
and 8-methoxyquinoline-substituted diaza-18-crown-6
ligands 01±4, Fig. 1) developed in our laboratories showed
signi®cantly improved ion-complexing and selectivity for
certain metal ions compared to unsubstituted diaza-18-
crown-6.9,10 Also these ligands have important luminescent
properties when treated with certain metal ions.3±5,11 Ligand
1 with the two 5-chloro-8-hydroxyquinoline 0CHQ) sub-
stituents attached through their C-7 positions has a high
af®nity for Mg21 and lower af®nity for the other alkaline
earth and alkali metal ions.10 Ligand 3 with the CHQ groups
attached through their C-2 positions, on the other hand,
exhibits very strong af®nity for Ba21 and no af®nity for
Mg21. Ligands 1 and 2 have proven to be effective chemo-
sensors for Mg21 and Hg21, respectively.4,5 And as a
chemosensor, ligand 4 selectively responds to Cd21, by an
increase in ¯uorescence.11
This paper reports the synthesis of two diaza-18-crown-6
Keywords: diazacrown ether; 8-aminoquinoline; reductive amination.
Corresponding author. Tel.: 11-801-378-2415; fax: 11-801-378-5474;
e-mail: jerald_bradshaw@byu.edu
p
Figure 1. 5-Chloro0or Nitro)-8-hydroxyquinoline-substituted diaza-18-
crown-6 ligands 1±4.
0040±4020/01/$ - see front matter q 2001 Elsevier Science Ltd. All rights reserved.
PII: S0040-4020001)00746-3

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G. Xue et al. / Tetrahedron 57 42001) 7623±7628
Scheme 1. Preparation of bis08-amino-2-quinolinylmethyl)-substituted diaza-18-crown-6 012).
2. Results and discussion
was very low 0,10%) due to the formation of an Fe0II)-
crown ether complex and it was dif®cult to effect decom-
plexation of this complex.
Two possible methods for synthesizing 7,16-bis08-amino-
2-quinolinylmethyl)-diaza-18-crown-6 012) were used
0Scheme 1). In the ®rst method, the diazacrown was treated
with 2-bromomethyl-8-nitroquinoline 06) followed by
reduction. Intermediate 6 was prepared in 30% yield by
bromination of 8-nitroquinaldine 05) with N-bromosuccini-
mide in re¯uxing CCl4. We tried to reduce the nitro groups
of compound 10 to form the desired diamino macrocycle 12
by catalytic hydrogenation using PtO2 as the catalyst.
Unfortunately, no desired products were obtained because
the 8-nitroquinoline groups were removed from the diaza-
crown by hydrogenation. Reduction of 10 was achieved
using powdered iron and acetic acid. However, the yield
The second method to prepare 12 used reductive ami-
nation12 of Boc-protected 8-amino-2-quinolinecarbox-
aldehyde 09) 0Scheme 1). The synthesis of key precursor 9
began with commercially available 8-aminoquinaldine 07),
which can be easily obtained by reduction of 8-nitroquinal-
dine 05) using powdered iron 084% yield) or by catalytic
hydrogenation using Pd±C as catalyst 095% yield). Amine 7
was treated with 0Boc)2O in 1,4-dioxane at 85±908C to give
Boc-protected 8 in 88% yield. Oxidation of 8 was
accomplished with SeO2 in 1,4-dioxane to provide 9 in
90% yield. Reductive amination was carried out by treating
Scheme 2. Preparation of bis08-amino-7-quinolinylmethyl)-substituted diaza-18-crown-6 016).

G. Xue et al. / Tetrahedron 57 42001) 7623±7628
7625
Figure 2. The crystal structure of 16. All hydrogen atoms were omitted for clarity except those of the primary amines.
diaza-18-crown-6 with 9 in the presence of NaBH0OAc)3 to
give Boc-protected macrocycle 11 in an 85% yield. The
removal of the Boc groups was accomplished in 90%
yield using 4.0 M HCl in 1,4-dioxane to give bis-8-amino-
quinoline appended diaza-18-crown-6 ligand 12.
ions. In particular, the two absorption bands undergo a
sizeable blue shift, while the luminescence intensity is
typically reduced. In acetonitrile, analysis of the pattern of
the absorption and ¯uorescence intensities as a function of
the molar equivalents of metal ions added to the solution
0Fig. 4) reveals a marked difference in the ion binding
behavior of the two ligands. In particular, with the metal
ions studied 0with the partial exception of Mg21) 16 forms
stable complexes in acetonitrile 0log Ka$7.0) with 1:1
0metal/ligand) stoichiometry. A similar behavior is shown
7,16-Bis08-amino-7-quinolinylmethyl)-diaza-18-crown-6
16 was also prepared by reductive amination 0Scheme 2).
Intermediate aldehydes 13 and 14 were prepared by the
published method.13 Diaza-18-crown-6 was treated with
13 and 14 in the presence of NaBH0OAc)3 to form 8-nitro-
quinoline- and 8-aminoquinoline-substituted diaza-18-
crown-6 ligands 15 and 16 in 80 and 75% yields, respec-
tively. As with the reduction of 10 to 12 0Scheme 1),
reduction of 15 to 16 by powdered iron and catalytic hydro-
genation occurred in very low yields.
by 12 only with Ca21, Sr21, and Ba21; while with Mg21
,
Zn21, Cd21, and Hg21, it forms complexes with different
stoichiometries 0see Fig. 4), as can be seen by the lackof
isosbestic points in the absorption spectra 0Fig. 3 for Hg21
)
and the appearance of multiple ¯uorescence bands during
the titration experiments. A complete characterization of all
the equilibria involved are in progress in our laboratories.
The solid state structure of 16 is shown in Fig. 2. The
conformation of the ligand suggests that the side-arms
would complex a metal ion guest in the cavity using the
primary amine nitrogen atoms. In the absence of a guest
cation, the amine nitrogen atom does interact with N9
and O3A of the macroring through a bifurcated H-bond
involving H21A. However, the quinoline ring nitrogens do
not appear to be available for complexation.
In conclusion, the synthetic approach presented here could
The absorption spectra of ligands 12 and 16 in acetonitrile
0Fig. 3) are dominated by two intense bands centered at 245
and 337 nm 012) and at 254 and 339 nm 016, see Table 1),
which are very similar to those observed for 1, 3, and 4 in
the same solvent.4,5,11 Compounds 12 and 16 ¯uoresce
intensively at 474 and 490 nm, respectively, in acetonitrile
0Table 1), while only very weaksignals can be observed in
protic solvents such as water and methanol. The lackof
¯uorescence in protic solvents can be ascribed to proton
transfer processes involving solvent molecules, similarly
to what was observed for 8-hydroxyquinoline derivatives.14
Figure 3. Absorption spectra of acetonitrile solutions of 12 02£1025 M) and
upon addition of up to 2.2 equiv. of Hg0ClO4)2.
The photophysical properties of 12 and 16 are drastically
changed upon addition of alkaline earth and transition metal

7626
G. Xue et al. / Tetrahedron 57 42001) 7623±7628
Table 1. Absorbance and ¯uorescence data of 12 and 16 and their
complexes with metal ions
be applied to the synthesis of any azacrown ether macro-
cycles bearing 8-aminoquinoline side arms attached either
through their positions 2 or 7. The photophysical properties
of 12 and 16 indicate that they may be useful as chemical
sensors for metal ions.
Compound
Absorbance
e 0M21cm21
Fluorescencea
l 0nm)
)
l 0nm)
Irel
1000
440
12
245
337
235
257
316
244
311
245
311
251
311
254
339
233
254
315
240
303
244
318
245
319
236
303
237
298
234
304
68,000
7000
46,000
41,000
6000
47,000
6000
36,000
5700
38,000
6000
71,000
6900
48,000
35,000
5200
83,000
7400
74,000
6400
72,000
6600
80,000
8500
80,000
9100
474
484
12´Mg21
3. Experimental
1
The H- and 13C NMR spectra were recorded at 200 or
12´Ca21
12´Sr21
12´Ba21
16
493
488
480
496
490
300
300
80
300 MHz and 50 or 75 MHz in CDCl3 unless otherwise
indicated. Melting points are uncorrected. HRMS spectra
were determined using fast atom bombardment 0FAB),
chemical ionization 0CI) and electron impact 0EI) methods.
Solvents and starting materials were purchased from
commercial sources were available. Compounds 13 and
14 were prepared as reported.13 The solvent for photo-
physical measurements was acetonitrile 0Merck, UVASOL)
that was used without further puri®cation. Absorption
spectra were recorded on a Perkin±Elmer lambda 40
spectrophotometer. Uncorrected emission and corrected
excitation spectra were obtained on a Fluorolog spectro-
¯uorimeter equipped with a R928 phototube. In order to
allow comparison of emission intensities, corrections for
instrumental response, inner ®lter effects,15 and phototube
sensitivity were performed. A correction for differences in
the refraction index was introduced when necessary.
1000
250
16´Mg21
16´Ca21
16´Sr21
16´Ba21
16´Zn21
16´Cd21
16´Hg21
451
464
451
450
450
±
180
160
150
10
80
67,000
12,000
±
3.1. Synthesis of new ligands
a
Excitation wavelengths were 300 nm for 12 and its complexes and
340 nm for 16 and its complexes.
3.1.1. 8-Nitro-2--bromomethyl)quinoline -6). A solution
of 8-nitroquinaldine 05) 01.65 g, 8.8 mmol) in 45 mL of
CCl4 was re¯uxed with N-bromosuccinimide 0NBS)
01.73 g, 9.7 mmol) in the presence of benzoyl peroxide
00.07 g) for 2 days. The hot solution was ®ltered. The
residue was puri®ed by column chromatography on silica
gel using hexane/CH2Cl2 02:1) as eluent to give 0.71 g
1
030%) of 6 as yellow crystals; mp 144±1468C; H NMR:
d 8.26 0d, Jˆ8.7 Hz, 1H), 8.02 0d, Jˆ8.1 Hz, 2H), 7.75 0d,
Jˆ8.7 Hz, 1H), 7.62 0t, Jˆ8.1 Hz, 1H), 4.71 0s, 2H); HRMS
m/z: calcd for C10H7N2O2Br 0M1): 265.9691, found:
265.9686. Anal. Calcd for C10H7N2O2Br: C, 44.97; H,
2.64. Found: C, 45.12; H, 2.72.
3.1.2. 8--t-Butoxycarbonylamino)quinaldine -8). 8-Amino-
quinaldine 07) 03.95 g, 25 mmol) was stirred with di-t-butyl-
dicarbonate 010.9 g, 50 mmol) in 70 mL of dioxane at
85±908C for two days. The solvent was removed under
reduced pressure and the residue was puri®ed by column
chromatography on silica gel using CH2Cl2/hexane 01:1) as
eluent to give 5.68 g 088%) of 8 as white crystals; mp 72±
738C; 1H NMR: d 9.06 0s, 1H), 8.38 0d, Jˆ7.2 Hz, 1H), 7.99
0d, Jˆ8.0 Hz, 2H), 7.47±7.28 0m, 3H), 2.73 0s, 3H), 1.59 0s,
9H); HRMS m/z: calcd for C15H19N2O2 0M1H)1: 259.1448,
found: 259.1430. Anal. Calcd for C15H18N2O2: C, 69.74; H,
7.02. Found: C, 70.00; H, 6.87.
3.1.3.
8--t-Butoxycarbonylamino)-2-quinolinecarbox-
aldehyde -9). To a stirred suspension of freshly sublimed
SeO2 03.33 g, 30 mmol) in 150 mL of dioxane at 50±558C
was added a solution of 8 04.34 g, 16.8 mmol) in 50 mL of
dioxane during the course of 3 h. The mixture was heated to
80±858C overnight, ®ltered, and the dioxane was removed
Figure 4. 0a) Fluorescence intensity 0lexcˆ300 nm, lemˆ485 nm) recorded
after addition of increasing amounts of Hg0ClO4)2 to a 2£1025 M aceto-
nitrile solution of 12 0X) or 16 0L). 0b) Absorbance 0lˆ300 nm) recorded
after addition of increasing amounts of Hg0ClO4)2 to a 2£1025 M aceto-
nitrile solution of 12 0X) or 16 0L).

G. Xue et al. / Tetrahedron 57 42001) 7623±7628
7627
under reduced pressure. The residue was puri®ed by column
chromatography on silica gel with CH2Cl2 as eluent to give
4.11 g 090%) of 9 as green crystals; mp 129±1318C; H
NMR: d 10.26 0s, 1H), 9.0 0s, 1H), 8.52 0d, Jˆ6.6 Hz,
1H), 8.30 0d, Jˆ8.8 Hz, 1H), 8.05 0d, Jˆ8.4 Hz, 1H), 7.66
0t, Jˆ8.0 Hz, 1H), 7.50 0d, Jˆ8.4 Hz, 1H); HRMS m/z:
calcd for C15H17N2O3 0M11)1: 273.1240, found:
273.1229. Anal. Calcd for C15H16N2O3: C, 66.16; H, 5.92.
Found: C, 66.06; H, 5.82.
8H); 2.95 0t, Jˆ5.6 Hz, 8H); 13C NMR: 158.0, 143.7, 137.5,
136.s2, 127.8, 126.7, 121.4, 115.9, 110.0, 70.8, 70.1, 62.3,
54.5; HRMS m/z: calcd for C32H42N6O4Na 0M1Na)1:
597.3169, found: 597.3146. Anal. Calcd for C32H42N6O4:
C, 66.88; H, 7.37. Found: C, 66.70; H, 7.15.
1
3.1.7.
7,16-Bis-8-nitro-7-quinolinylmethyl)diaza-18-
crown-6 -15). Macrocycle 15 was prepared as above for
11 from diaza-18-crown-6 0393 mg, 1.5 mmol) and 13
0666 mg, 3.3 mmol). Crude compound 15 was puri®ed by
column chromatography on silica gel with acetone as eluent
to give an 80% yield of pure 15; mp 141±1438C, 1H NMR:
8.94 0d, Jˆ3.0 Hz, 2H), 8.18 0d, Jˆ8.4 Hz), 7.86 0d, Jˆ
3.0 Hz, 4H), 7.47 0dd, Jˆ4.0 and 8.4 Hz), 3.93 0s, 4H),
3.65 0t, Jˆ5.6 Hz, 8H), 3.60 0s, 8H), 2.87 0t, Jˆ5.6 Hz,
8H); 13C NMR: d 152.0, 147.7, 139.4, 135.6, 132.9,
129.1, 127.8, 127.7, 122.3, 70.7, 69.7, 55.1, 54.1; HRMS
m/z: calcd for C32H38N6O8Na 0M1Na)1: 657.2651, found:
657.2649. Anal. Calcd for C42H38N6O8: C, 60.56; H, 6.03.
Found: C, 60.40; H, 6.18.
3.1.4.
7,16-Bis-8-nitro-2-quinolinylmethyl)diaza-18-
crown-6 -10). A solution of 6 02.4 g, 9.0 mmol) in 50 mL
of benzene was added dropwise to a solution of diaza-18-
crown-6 01.0 g, 3.8 mmol) and triethylamine 01.6 g,
15.8 mmol) in 50 mL of benzene under nitrogen. The
mixture was stirred at room temperature for 20 h and then
re¯uxed for 2 h. The solvent was evaporated under reduced
pressure. The residue was treated with a mixture of water
and CH2Cl2 01:2). The organic layer was separated, washed
with water, and dried 0Na2SO4). After evaporation, the
residue was puri®ed by column chromatography on silica
gel with acetone as eluent. The product was recrystallized
from CH2Cl2/EtOH to give 1.98 g 082%) of 10 as white
3.1.8.
7,16-Bis-8-amino-7-quinolinylmethyl)diaza-18-
crown-6 -16). Macrocycle 16 was prepared as above for
11 from diaza-18-crown-6 0393 mg, 1.5 mmol) and 14
0567 mg, 3.3 mmol). Crude compound 16 was puri®ed by
column chromatography on silica gel with acetone/Et3N
010:1) as eluent to give a 75% yield of the pure product;
1
crystals; mp 124±1268C; H NMR: d 8.12 0d, Jˆ8.4 Hz,
2H), 7.95±7.89 0m, 6H), 7.51 0t, Jˆ7.8 Hz, 2H), 4.07 0s,
4H), 3.68 0t, Jˆ5.7 Hz; 8H), 3.62 0s, 8H), 2.93 0t, Jˆ5.7 Hz,
8H); 13C NMR: d 164.6, 148.3, 138.9, 136.1, 131.7, 128.3,
124.6, 123.3, 123.1, 71.0, 70.1, 62.2, 54.8; HRMS m/z: calcd
for C32H38N6O8Na 0M1Na)1: 657.2651, found: 657.2656.
Anal. Calcd for C32H38N6O8: C, 60.56; H, 6.03. Found: C,
60.70; H, 5.84.
1
mp 150±1528C; H NMR: d 8.74±8.72 0m, 2H), 8.02 0dd,
Jˆ1.8 and 8.4 Hz, 2H), 7.30 0dd, Jˆ4.4 and 8.4 Hz, 2H),
7.19 0d, Jˆ8.6 Hz, 2H), 7.03 0d, Jˆ8.6 Hz, 2H), 6.20 0s,
4H), 3.82 0s, 4H), 3.62 0t, Jˆ5.4 Hz, 8H), 3.54 0s, 8H),
2.80 0d, Jˆ5.4 Hz, 8H); 13C NMR: d 147.2, 144.5, 138.4,
135.8, 129.7, 128.1, 120.8, 118.4, 113.9, 70.6, 96.6, 59.1,
54.2; HRMS m/z: calcd for C32H42N6O4Na 0M1Na)1:
597.3169, Found: 597.3172. Anal. Calcd for C32H42N6O4:
C, 66.88; H, 7.37. Found: C, 66.77; H, 7.43.
3.1.5. 7,16-Bis[-8-t-butoxycarbonylamino)-2-quinolinyl-
methyl]diaza-18-crown-6 -11). A mixture of diaza-18-
crown-6 0393 mg, 1.5 mmol) and 9 0898 mg, 3.3 mmol) in
25 mL of dichloroethane was stirred with NaBH0OAc)3
0848 mg, 4.0 mmol) under nitrogen at room temperature
for 5 h. The reaction was then quenched with saturated
Na2CO3 015 mL) and the mixture was extracted with
CH2Cl2 03£10 mL). The combined CH2Cl2 extracts were
dried 0Na2SO4), ®ltered, and concentrated on a rotary
evaporator. The residue was puri®ed by column chroma-
tography on silica gel with acetone as eluent to give
3.2. X-Ray crystallography data
Crystal data and experimental details are listed in Table 2.
Table 2. Crystal data and experiment details for 16
Formula
C32H42N6O4
1
987 mg 085%) of 11 as white crystals; mp 48±50 8C; H
Formula weight
Crystal system
Space group
574.72
Monoclinic
P21/n
7.0482013)
19.62904)
11.23302)
98.0302)
1538.903)
2
NMR: d 9.0 0s, 2H), 8.40 0d, Jˆ7.2 Hz, 2H), 8.08 0d,
Jˆ8.4 Hz, 2H), 7.75 0d, Jˆ8.4 Hz, 2H), 7.44 0m, 4H),
4.06 0s, 4H), 3.70 0t, Jˆ5.6 Hz), 3.64 0s, 8H), 2.96 0t, Jˆ
5.6 Hz), 1.61 0s, 18H); 13C NMR: d 159.1, 152.9, 137.2,
136.5, 134.8, 127.0, 126.7, 121.5, 119.9, 114.3, 70.8, 70.1,
62.2, 54.5, 28.4; HRMS m/z: calcd for C42H58N6O8Na
0M1Na)1: 797.4217. found: 797.4196. Anal. Calcd for
C42H58N6O8: C, 65.09; H, 7.54. Found: C, 65.10; H, 7.57.
Ê
a 0A)
Ê
b 0A)
Ê
c 0A)
b 08)
V 0A )
Ê 3
Z
F0000)
Dx 0g cm23
Crystal size 0mm)
616
1.240
)
0.40£0.35£0.20
3.1.6.
7,16-Bis-8-amino-7-quinolinylmethyl)diaza-18-
m 0mm21
)
0.083
293
crown-6 -12). Compound 11 0774 mg, 1.0 mmol) was
treated with 4.0 M HCl in 50 mL of dioxane and the mixture
was allowed to stir for 12 h. A chilled solution of 3N NaOH
080 mL) was added dropwise to the mixture. Solid 12 was
®ltered and recrystallized from CH2Cl2/EtOH 01:1) to give a
90% yield of the pure product; mp 114±1158C; 1H NMR: d
8.01 0d, Jˆ8.4 Hz, 2H); 7.65 0d, Jˆ8.4 Hz, 2H); 7.34±7.26
0m, 2H); 7.12 0d, Jˆ7.2 Hz, 2H); 6.91 0d, Jˆ7.2 Hz, 2H);
4.98 0s, 4H), 4.02 0s, 4H); 3.69 0t, Jˆ5.6 Hz, 8H); 3.64 0s,
Temperature 0K)
2umax 08)
Total data
50.0
2941
Independent data
Total parameters
Goodness of ®t on F2
R[I.20-0I)]
2710 0Rintˆ0.0171)
191
1.015
0.0450
0.0776
0.129, 20.139
R 0all data)
Largest diff peakand
Ê 23
hole 0eA
)

7628
G. Xue et al. / Tetrahedron 57 42001) 7623±7628
2. Bargossi, C.; Fiorini, M. C.; Montalti, M.; Prodi, L.;
Zaccheroni, N. Coord. Chem. Rev. 2000, 208, 17.
3. Xue, G.-P.; Savage, P. B.; Bradshaw, J. S.; Zhang, X. X.; Izatt,
R. M. Functionalized macrocyclic ligands as sensory
molecules for metal ions. Advances in Supramolecular
Chemistry; Gokel, G. W., Ed.; JAI: New York, 2000; Vol.
7, pp. 99±137.
Single crystal data were collected using a Bruker P4 auto-
mated diffractometer which utilized graphite mono-
chromated MoKa radiation. The structure was solved
using the direct method and re®ned on F2 using a full
matrix, least-squares procedure. All non-hydrogen atoms
were re®ned anisotropically. Positions for hydrogen
atoms, except for the two amine hydrogens, were calculated
based on geometrical factors. The positions for the amine
hydrogen atoms were obtained from a difference map. All
hydrogens were allowed to ride on their neighboring heavy
atoms during re®nement. The structure was solved, re®ned
and displayed using SHELXTL PC16 computer program
package.
4. Prodi, L.; Bolletta, F.; Montalti, M.; Zaccheroni, N.; Savage,
P. B.; Bradshaw, J. S.; Izatt, R. M. Tetrahedron Lett. 1998, 39,
5451.
5. Prodi, L.; Bargossi, C.; Montalti, M.; Zaccheroni, N.; Su, N.;
Bradshaw, J. S.; Izatt, R. M.; Savage, P. B. J. Am. Chem. Soc.
2000, 122, 6769.
6. Xue, G.-P.; Bradshaw, J. S.; Chiara, J. A.; Savage, P. B.;
Krakowiak, K. E.; Izatt, R. M.; Prodi, L.; Montalti, M.;
Zaccheroni, N. Synlett 2000, 1181.
3.3. Experimental data for UV±Vis and ¯uorescence
titration experiments
7. Su, N.; Bradshaw, J. S.; Zhang, X. X.; Song, H.-C.; Savage,
P. B.; Xue, G.-P.; Krakowiak, K. E.; Izatt, R. M. J. Org. Chem.
1999, 64, 8855.
In a typical experiment, a solution of ligand 0concentration
2£1025 M) in dry acetonitrile was titrated by increasing
amounts of a solution of the perchlorate salt of the cation
of interest 0concentration 5£1023 M) at room temperature.
After each addition of aliquots, the UV±Vis and ¯uor-
escence spectra of the solution were recorded. When the
titration was completed, the spectra were implemented
into the Speci®t software.17
8. Yang, Z.; Bradshaw, J. S.; Zhang, X. X.; Savage, P. B.;
Krakowiak, K. E.; Dalley, N. K.; Su, N.; Bronson, T.; Izatt,
R. M. J. Org. Chem. 1999, 64, 3162.
9. Zhang, X. X.; Bordunov, A. V.; Bradshaw, J. S.; Dalley, N. K.;
Kou, K.-L.; Izatt, R. M. J. Am. Chem. Soc. 1995, 117, 11507.
10. Bordunov, A. V.; Bradshaw, J. S.; Zhang, X. X.; Dalley, N. K.;
Kou, K.-L.; Izatt, R. M. Inorg. Chem. 1996, 35, 7229.
11. Prodi, L.; Montalti, M.; Zaccheroni, N.; Bradshaw, J. S.; Izatt,
R. M.; Savage, P. B. Tetrahedron Lett. 2001, 42, 2941.
12. Abdel-Magid, A. F.; Carson, K. G.; Harris, B. D.; Maryanoff,
C. A.; Shah, R. D. J. Org. Chem. 1996, 61, 3849.
13. Riesgo, E. C.; Jin, X.; Thummel, R. P. J. Org. Chem. 1996, 61,
3017.
Acknowledgements
Financial support from the Of®ce of Naval Research 0J. S. B.,
P. B. S., and R. M. I.) and the Italian Ministry of University
Research and Technology 0Solid Supermolecules and
Arti®cial Photosynthesis projects, L. P., M. M. and M. Z.)
is gratefully acknowledged.
14. Bardez, E.; Devol, B.; Larrey, B.; Valeur, B. J. Phys. Chem.
1997, 101, 7786.
15. Credi, A.; Prodi, L. Spectrochim. Acta, Part A 1998, 54, 159.
16. Sheldrick, G. M. SHELXTL PC, version 5.03, Bruker
Analytical X-ray Systems, Madison, Wisconsin, 1994.
17. Binstead, R. A. SPECFIT; Spectrum Software Associates:
Chappell Hill, NC, 1996. Gampp, H.; Maeder, M.; Meyer,
C. J.; ZuberbuÈhler, A. D. Talanta 1985, 32, 257.
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