144 J. Am. Chem. Soc., Vol. 119, No. 1, 1997
Oude Wolbers et al.
[25,26,27-Tris(carboxylatomethoxy)-4,9,23-trimethyl)-16-octade-
cyl-13,19-dioxa-16-azatetracyclo[19,3,1,12,6,17,11]heptacosa-1(25),2,4,6-
(27),7,9,11(26),21,23-nonaene-14,14′,15,15′,17,17′,18,18′-d8(3-)]eu-
ropium(3+) (11b‚Eu3+). The Eu3+ complex 11b‚Eu3+ was obtained
using bridge-deuterated triacid 10b (79.4 mg, 0.090 mmol), Et3N (0.037
mL, 0.27 mmol), and EuCl3‚6H2O (37.9 mg, 0.103 mmol) in MeOH
(1.0 and 0.5 mL, respectively). The Eu3+ complex was obtained in
94% yield as an off-white solid. Mp: >300 °C. IR (KBr): 2207,
2097, 1611 cm-1. MS (FAB): m/z 1034.6 [(M + H)+], 976.4 [(M -
CH2COO)+], 916.6 [(M - 2CH2COO)+]. Anal. Calcd for C51H62-
D8NO11Eu: H, 6.05; N, 1.36; Eu3+, 14.7. Found: H, 6.07; N, 0.94;
Eu3+, 15.6.
organic ligand, is relatively high. Excellent agreement between
the results of the photophysical studies and the MD calculations
is obtained, which allows the use of molecular dynamics as a
tool to predict the composition of the coordination sphere.
Experimental Section
Photophysical Studies. Luminescence spectra were recorded for
λem ) 550-725 nm with a PTI (Photon Technology International, Inc.)
Alphascan spectrofluorometer after excitation of the Eu3+ ion at λexc
) 393, or 287 nm. Measurements were carried out either in the steady
state mode, where the signal from the Hamamatsu R928 photomultiplier
was fed to a photon-counting interface and detected, or in the phase-
resolved mode. In the latter mode the excitation beam is modulated
in intensity at a frequency of 30-400 Hz by means of an optical
chopper. The modulated luminescence signal is subsequently analyzed
with a Stanford Research SR530 lock-in amplifier. The frequency
dependence of the phase shift and demodulation of the luminescence
signal are fitted to well-known expressions applied for phase-resolved
luminescence data.29 Because of the sensitivity of the Eu3+ lumines-
cence lifetimes and intensities to the water content of the solutions,
methanol was dried over molecular sieves (3 Å) prior to use and the
lifetimes and luminescence spectra were recorded using freshly prepared
samples.
[25,26,27-Tris(carboxylatomethoxy-31,31′-32,32′-33,33′-d6)-4,9,-
23-trimethyl-16-octadecyl-13,19-dioxa-16-azatetracyclo[19,3,1,12,6,17,11]-
heptacosa-1(25),2,4,6(27),7,9,11(26),21,23-nonaene(3-)] europium-
(3+) (11c‚Eu3+). The synthesis of the Eu3+ complex 11c‚Eu3+ was
carried out using triacid 10c (0.52 g, 0.59 mmol), Et3N (0.25 mL, 1.77
mmol), and EuCl3‚6H2O (0.24 g, 0.66 mmol) in MeOD (7 and 3 mL,
respectively). The complex was obtained in 86% yield as an off-white
solid. Mp: >300 °C. IR (KBr): 2207, 2156, 2097, 1612 cm-1. MS
(FAB): m/z 1032.5 [(M + H)+], 972.7 [(M - CD2COO)+], 910.4 [(M
- 2CD2COO)+]. Anal. Calcd for C51H64D6NO11Eu: H, 6.26; N, 1.36;
Eu3+, 14.7. Found: H, 6.16; N, 1.02; Eu3+, 15.8.
[25,26,27-Tris(carboxylatomethoxy-31,31′,32,32′,33,33′-d6)-4,9,-
23-trimethyl-16-octadecyl-13,19-dioxa-16-azatetracyclo[19,3,1,12,6,17,11]-
heptacosa-1(25),2,4,6(27),7,9,11(26),21,23-nonaene-14,14′,15,
15′,17,17′,18,18′-d8(3-) europium(3+) (11d‚Eu3+). The bridge- and
arm-deuterated Eu3+ complex 11d‚Eu3+ was synthesized using triacid
10d (0.14 g, 0.16 mmol), Et3N (0.065 mL, 0.47 mmol), and EuCl3‚6H2O
(63.3 mg, 0.173 mmol) in MeOD (2 and 1 mL, respectively). Yield:
94% (off-white solid). Mp: >300 °C. IR (KBr) 2207, 2156, 2097,
1612 cm-1. MS (FAB): m/z 1040.5 [(M + H)+], 980.4 [(M - CD2-
COO)+], 918.4 [(M - 2CD2COO)+]. Anal. Calcd for C51H56D14NO11-
Eu: H, 5.43; N, 1.35. Found: H, 5.82; N, 1.06.31
Synthesis. Melting points were determined with a Reichert melting
point apparatus and are uncorrected. Mass spectra were recorded with
a Finnigan MAT 90 spectrometer using m-NBA (nitrobenzyl alcohol)
as a matrix, unless otherwise stated. IR spectra were obtained using a
Biorad 3200 or a Nicolet 5SXC FT-IR spectrophotometer. Elemental
analysis30 was performed using a Carlo Erba EA1106. The Eu3+ content
was determined by destroying the ligand in the presence of concentrated
nitric acid and concentrated perchloric acid. The remaining acids were
evaporated and the salts dissolved in Q2 water, followed by the addition
of an acetate buffer to keep the pH at 5-5.5, and a drop of pyridine
was added. After heating to 60 °C a titration with an aqueous solution
of 0.01 M EDTA (ethylenediamine tetraacetate) was carried out using
xylenol orange as an indicator. MeOH was dried over molecular sieves
(3 Å) for at least 3 days. EuCl3‚6H2O was of reagent grade and was
used after heating under reduced pressure. The synthesis procedures
and the analytical evidence for the formation of the compounds 2-10,
17-28, and 30-33 are available as Supporting Information.
[25,26,27-Tris(carboxylatomethoxy)-4,9,23-tri-tert-butyl-16-dode-
cyl-13,19-dioxa-16-azatetracyclo[19,3,1,12,6,17,11]heptacosa-1(25),2,4,6-
(27),7,9,11(26),21,23-nonaene(3-)]europium(3+) (29‚Eu3+). The
reaction was carried out using triacid 28 (0.10 g, 0.11 mmol), Et3N
(46 µL, 0.33 mmol) in MeOH (3 mL), and EuCl3‚6H2O (0.04 g, 0.12
mmol) in MeOH (1 mL). The off-white solid 29‚Eu3+ was obtained
in 63% yield. Mp: >300 °C. IR (KBr): 1635 cm-1. MS (FAB):
m/z 1067.4 (M+). Anal. Calcd for C54H76NO11Eu: H, 7.18; N, 1.31;
Eu3+, 14.2. Found: H, 6.92; N, 1.03; Eu3+, 12.8.
General Procedure for the Complexation of Eu3+. The corre-
sponding triacid was dissolved in MeOH, after which 3 equiv of Et3N
was added using a microsyringe. Subsequently a solution of EuCl3‚6H2O
in a minimal amount of MeOH was added in one portion, upon which
the complex precipitated immediately as an almost white solid. The
reaction mixture was stirred for an additional 15 min and concentrated
(to ∼3 mL), after which the complex was filtered off. The product
was purified by refluxing it in CH3CN for 3 h, after which it was
concentrated (to ∼3 mL) and cooled to 0 °C. The product was filtered
off and washed once with cold CH3CN (∼3 mL).
[25,26,27-Tris(carboxylatomethoxy)-4,9,23-tri-tert-butyl-13,16,19-
trioxatetracyclo[19,3,1,12,6,17,11]heptacosa-1(25),2,4,6(27),7,9,
11(26),21,23-nonaene(3-)] europium(3+) (34‚Eu3+). The reaction
was carried out using triacid 33 (0.20 g, 0.27 mmol), Et3N (0.11 mL,
0.81 mol) in MeOH (5 mL), and EuCl3‚6H2O (0.12 g, 0.32 mmol) in
MeOH (2 mL). The off-white solid 34‚Eu3+ was obtained after the
addition of diisopropyl ether in 67% yield. Mp: >300 °C. IR (KBr):
1612 cm-1. MS (FAB): m/z 899.5 [(M + H)+], 865.6 [(M + Na -
CH2COO)+]. Anal. Calcd for C42H52O12Eu: H, 5.71; Eu3+, 16.9.
Found: H, 5.47; Eu3+, 17.9.
[25,26,27-Tris(carboxylatomethoxy)-4,9,23-trimethyl-16-octade-
cyl-13,19-dioxa-16-azatetracyclo[19,3,1,12,6,17,11]heptacosa-1(25),2,4,6-
(27),7,9,11(26),21,23-nonaene(3-)]europium(3+) (11a‚Eu3+). The
reaction was carried out using triacid 10a (0.80 g, 0.83 mmol), Et3N
(0.34 mL, 2.47 mol) in MeOH (10 mL), and EuCl3‚6H2O (0.34 g, 0.93
mmol) in MeOH (3 mL). The off-white solid 11a‚Eu3+ was obtained
Acknowledgment. Akzo Nobel Research is gratefully
acknowledged for financial and technical support.
in quantitative yield. Mp: >300 °C. IR (KBr): 1608 cm-1
. MS
(FAB): m/z 1026.4 [(M + H)+], 968.5 [(M - CH2COO)+], 908.3 [(M
- 2CH2COO)+]. Anal. Calcd for C51H70NO11Eu‚2.75H2O: H, 7.08;
N, 1.30; Eu3+, 14.1. Found: H, 6.87; N, 1.31; Eu3+, 14.1. Karl-Fisher
calcd for 2.75 mol of H2O: 4.61. Found: 4.63.
Supporting Information Available: Synthesis procedures
and analytical evidence for the formation of the products 2-10,
17-28, and 30-33 (23 pages). See any current masthead page
for ordering and Internet access instructions.
(29) Lakowicz, J. R. Principle of Fluorescence Spectroscopy, 2nd ed.;
Plenum: New York, 1989; pp 52-57.
JA9609314
(30) The C content of the Eu3+ complexes determined by elemental
analysis was too low probably due to the formation of very stable Eu3+
carbides or carbonates (Tdec > 1800 °C).
(31) For Eu3+ no satisfactory elemental analysis could be obtained.