ReVersible Oxy-Anion Binding
J. Am. Chem. Soc., Vol. 122, No. 40, 2000 9683
total anion concentration and Lni is the complex concentration.
-13.6 (1H, s), -14.1 (1H, s), -15.2 (1H, s), -15.5 (1H,s), -18.5
(1H,s). In the presence of 20 mM NaHCO3 (pD 8.6): 27.5 (1H, s,
NH), 11.5 (1H, s), 10.6 (1H, s), 1.8 (3H, s, CH3), 1.6 (6H, CH3), 0.0
(1H, s), -2.5 (1H, s), -3.5 (3H, br s), -8.2 (1H, s), -8.9 (2H, s),
-9.4 (1H, s), -10.9 (1H, s), -11.1 (1H, s), -11.5 (1H, s), -15.4
(1H, s).
(Iobs - Iinit
)
2[Lni]
) [Lni] + [Ai] + 1/K - ({[Lni] + [Ai] +
(Ifinal - Iinit
)
1/K}2 - 4[Lni][Ai])1/2
Complexes of Tb with L1a, L1b, and L1c were prepared analogously
and gave identical IR spectra and ESMS data in accord with the
theoretical isotope patterns for the complex plus one or two triflate
counterions. Complexes of Eu with L1b and L1c also gave confirmatory
accurate mass data and the following NMR data in the presence of the
Statistical errors were estimated be <10%, and experimental errors (the
mean of three values is given in Table 1) were within 20%.
Ligand and Complex Synthesis. (SSS)-1,4,7-Tris[1-(1-phenyl)-
ethylcarbamoylmethyl]-1,4,7,10-tetraazacyclododecane, L1a. (S)-N-
(2-Chloroethanoyl)-2-phenylethylamine (1.17 g, 5.9 mmol) in dry
ethanol (10 mL) was added dropwise over 8 h to a stirred solution of
1,4,7,10-tetraazacyclododecane (0.34 g, 2.0 mmol) and triethylamine
(0.83 mL, 5.9 mmol) in dry ethanol (30 mL) at 60 °C. The mixture
was boiled under reflux for 18 h, concentrated to small volume, poured
into aqueous hydrochloric acid (0.1 M, 40 mL), and washed with diethyl
ether (3 × 30 mL). The aqueous phase was neutralized by careful
addition of sodium hydroxide (1 M), the pH was adjusted to 13, and
the solution extracted with dichloromethane (3 × 30 mL). Extracts were
dried (K2CO3) and the solvent was removed to yield an oily residue
which was purified by chromatography on neutral alumina (100% CH2-
Cl2 to 2% MeOH/CH2Cl2) to yield a pale yellow solid (380 mg, 29%):
mp 63-65 °C; Rf (Al2O3; 10% MeOH/CH2Cl2) 0.5. HR-ESMS (m/z):
[M + H]+ calcd for C38H54N7O3, 656.4288; found, 656.4287. 1H NMR
(CDCl3, δ): 7.30 (3H, s, NHCO), 7.29-7.21 (15H, mult, ArH), 5.12
(3H, dq + dq, CH), 2.97 (4H, s, CH2CO), 2.93 (2H, s, CH2C′O), 2.58
(16H, br mult, CH2N), 1.80 (1H, br s, NH), 1.48 (6H, d, J ) 7.2, CH3),
1.45 (3H, d, CH3). 13C NMR (CDCl3, δ): 170.8, 170.6, 143.7
(quaternary), 129.1 (meta ArC), 127.8 (para ArC), 127.0, 59.9 (CH2-
CO), 58.0 (CH2CO), 54.5 (CH2N), 53.6 (CH2N), 48.9 (CHN), 48.6
(CHN), 22.1, 21.9. Anal. Calcd for C38H53N7O3‚2H2O: C, 66.0; H,
8.30; N, 14.2. Found: C, 65.7; H, 8.54; N, 14.0.
1
given anion: [EuL1b(H2O)(CF3SO3)3]3+ partial H NMR (pD 6, 400
MHz, 293K) δ: 25.3 (1H, s Hax), 19.8 (2H, br s, Hax), 19.1 (1H, s,
Hax), -0.9 (3H, s, CH3), -1.1 (6H, s, CH3), -3.8 to -4.3 (4H, mult),
-6.1 (1H, s), -6.8 (1H, s), -7.2 (1H, s), -7.5 (1H, s), -7.9 (1H, s),
-8.0 (1H, s), -8.8 (1H, s), -12.2 (1H, s), -12.5 (1H, s), -12.8 (1H,
s), -13.9 (1H, s), -18.1 (1H, s). [EuL1b(CO3)]+ partial 1H NMR (pD
6, 500 MHz, 293 K; primed protons are geminally coupled, e.g.,Hx
and H′x) δ: 13.9 (1H, s, Ha), 9.46 (2H, s, ArH), 8.56 (3H, s, ArH +
Hb), 8.06 (1H, br s, ArH), 7.80 (3H, br s, ArH + Hc), 7.69 (2H, s,
ArH), 7.25 (2H, br m, ArH + Hd), 6.98 (2H, s, ArH), 6.19 (2H, s,
ArH), 6.08 (1H, s, CHCH3), 6.07 (1H, s, CH′(CH3), 5.68 (1H, s,
CH′CH3), 5.51 (3H, s, NCH3), 4.11 (1H, s, He), 3.67 (1H, s, Hf), 3.38
(1H, s, Hg), 1.36 (6H, s, CH3), 1.06 (3H, s, CH3), 0.03 (1H, s, H′a),
-0.93 (1H, s, CHxCO), -2.59 (1H, s, H′e), -6.00 (1H, s, H′d), -6.41
(2H, s, H′b + Hh), -7.77 (1H, s, H′f), -8.31 (1H, s, H′h), -8.73 (1H,
s, H′e), -10.35 (1H, s, H′g), -10.69 (1H, s, CHyCO), -11.77 (1H, s,
CH′xCO), -13.32 (1H, s, CHzCO), -13.83 (1H, s, CH′yCO), -18.47
(1H, s, CH′zCO). [EuL1b(CH3CO2)]2+ partial 1H NMR (pD 6, 300 MHz,
295 K) δ: 18.2 (1H, s), 18.0 (1H, s), 16.7 (1H, s), 15.9 (1H, s, Hax);
11.5 (1H, s, ArH); -2.19 (1H, s), -2.46 (5H, br s), -5.5 (1H, s),
-6.2 (1H, s), -6.4 (1H, s), -7.4 (1H, s), -7.8 (2H, s), -9.1 (1H, s),
-10.1 (1H, s), -10.5 (2H, s), -12.0 (1H, s), -15.3 (1H, s), -17.0
(1H, s).
(SSS)-1,4,7-Tris[1-(1-phenyl)ethylcarbamoylmethyl]-10-methyl-
1,4,7,10-tetraazacyclododecane, L1b. Compound L1a (0.1 g) was added
to a solution of formic acid (2 mL) and aqueous formaldehyde (38%,
2 mL) and the mixture was boiled under reflux for 20 h. After removal
of the solvent, the residue was treated with aqueous sodium hydroxide
solution (2 M, 10 mL) and extracted with chloroform (3 × 10 mL).
The combined extracts were dried (K2CO3) and the solvent was removed
under reduced pressure to yield a colorless solid: mp 54-56 °C. HR-
ESMS (m/z): [M + H]+ calcd for C39H56N7O3, 670.4444; found,
670.4446. 1H NMR (CDCl3, δ): 7.20 (15H, m, ArH), 5.05 (3H, dq +
dq, CHN), 2.90 (3H, s, N-CH3), 2.45-2.01 (22H, br m, CH2N), 1.41
(6H, d, J ) 7.2, CH3), 1.38 (3H, d, CH3). 13C NMR (CDCl3, δ): 171.0,
170.3, 143.8, 129.4, 129.3, 128.2, 128.1, 127.2, 126.9, 60.5, 59.8 (CH2-
CO), 56.8, 54.8, 54.7, 53.4 (CH2N), 48.9, 48.8 (CH), 44.8 (CH3N),
28.1, 21.9. λmax(H2O), 255 (510 dm3 mol-1 cm-1).
(SSS)-1,4,7-Tris[1-(1-p-carboxymethylphenyl)ethylcarbam-
oylmethyl]-1,4,7,10-tetraazacyclododecane, L2. This was prepared as
described for L1a using (S)-N-(2-chloroethanoyl)-2-(p-carboxymeth-
ylphenyl)ethylamine and was purified by chromatography on neutral
alumina by gradient elution (CH2Cl2, 1-5% MeOH (CH2Cl2) to yield
a pale yellow solid: mp 71-72 °C. HR-ESMS (m/z): [M + H]+ calcd
for C44H60N7O9, 830.4452; found, 830.4451. 1H NMR (CDCl3, δ): 7.86
(6H, d, ArH), 7.26 (6H, d, ArH), 5.05 (3H, dq + dq, CHN), 3.84 (9H,
s, OCH3), 2.89-2.50 (22H, br mult, CH2N), 1.65 (6H, d, CH3), 1.38
(3H, d, CH3). λmax(H2O), 256 (710 dm3mol-1cm-1).
1-(2′-Methylphenanthridinyl)-1,4,7,10-tetraazacyclododecane. 2-
Methylphenanthridine (317 mg, 1.64 mmol) was dissolved in CCl4 (20
mL) and a small amount of AIBN (4 mg) was added. N-Bromosuc-
cinimide (297 mg, 1.66 mmol, 1.0 equiv.) was added and the resultant
solution was stirred at 60 °C. The progress of the reaction was
monitored by TLC analysis (silica, 5% MeOH/CH2Cl2, product Rf 0.3),
and after 1.5 h the solution was cooled and filtered and the solvent
was removed under reduced pressure to give the 2-bromomethyl
1
compound (ca. 290 mg, 65%, as estimated by H NMR analysis) as a
cream-colored solid which was used immediately, in the next step. 1H
NMR (CDCl3): δ 4.71 (2H, s, CH2Br), 7.68 (1H, dd, H-9), 7.71 (1H,
dd, H-3), 7.82 (1H, dt, J ) 8.4, H-8), 8.00 (1H, br d, J ) 7.5, H-4),
8.11 (1H, br d, J ) 8.4, H-10), 8.57 (1H, d, J ) 8.1, H-7) 8.52 (1H,
d, J ) 1.8, H-1), 9.23 (1H, s, H-6).
The crude 2-bromomethylphenanthridine was taken up in dry CH3-
CN (15 mL), cyclen (1.9 g, 11.0 mmol) and Cs2CO3 (540 mg, 1.65
mmol) were added, and the resultant mixture was stirred at 80 °C. TLC
analysis (5% MeOH/CH2Cl2) after 45 min indicated that all of the
2-bromomethylphenanthridine had been consumed. The reaction mixure
was filtered, and the solvent was removed under vacuum to leave a
yellow hygroscopic oil. The residue was taken into CH2Cl2(30 mL)
and washed extensively with Purite water (5 × 100 mL) to remove
residual cyclen. The organic layer was dried (Na2SO4), filtered, and
evaporated to dryness to afford the title compound (285 mg, 71%) as
a hygroscopic yellow solid, which was used without further purification.
1H NMR (CDCl3): δ 2.46-2.78 (20H, m, ring CH2N + NH), 3.78
(2H, s, CH2), 7.54 (1H, t, H-9), 7.60 (1H, br d, H-3), 7.72 (1H, t, J )
8.0, H-8), 7.91 (1H, d, J ) 8.0, H-4), 8.04 (1H, d, J ) 8.4, H-10), 8.47
(1H, br s, H-1), 8.55 (1H, d, J ) 8.0, H-7) 9.14 (1H, s, H-6). HR-
ESMS (m/z): [M + H]+ calcd for C22H30N5, 364.2501; found, 364.2500.
(SSS)-1-(2′-Methylphenanthridinyl)-4,7,10-tris-[1-(1-phenyl)eth-
ylcarbamoylmethyl]-1,4,7,10-tetraazacyclododecane, L1c. 1-(2′-Me-
thylphenanthridinyl)-1,4,7,10-tetraazacyclododecane (285 mg, 0.785
mmol), (S)-N-2-chloroethanoyl-1-phenylethylamine (488 mg, 2.47
mmol, 3.1 eq) and cesium carbonate (850 mg, 2.61 mmol) were stirred
overnight in a mixture of CH3CN (4 mL) and CH2Cl2 at 80 °C. The
solution was filtered, and the solvent was removed under reduced
[EuL1a](CF3SO3)3(H2O)2. Europium triflate (0.09 g, 0.15 mmol) and
L1a (0.10 g, 0.15 mmol) were dissolved in dry MeCN (2 mL) and the
solution was boiled under reflux for 18 h. The volume was reduced to
ca. 0.5 mL, and the solution was added with stirring to cold, dry diethyl
ether (50 mL). A colorless solid precipitated which was filtered, dried
under high vacuum, and reprecipitated by following the same procedure
to yield a solid (0.12 g, 65%): mp 178-79 °C. HR-ESMS (m/z): [M
+ (CF3SO3)]2+ calcd for C39H53EuF3N7O6S, 957.2959; found, 957.2969.
IR (KBr): 3288 (br, NH), 1620 (CO) cm-1. 1H NMR (D2O, pD 6, 300
MHz, δ): (partial data and assignment) 27.3 (ring NH), 18.2, 15.5,
11.6, 10.1 (ring Haxial), 1.2 (3H, s), 0.1 (3H, s), -1.0 (3H, s, CH3),
-3.04 (1H, s), -4.04 (2H, s), -4.45 (1H, s), -4.8 (2H, s), -6.85
(1H, s), -8.74 (1H, s), -9.45 (1H, s), -9.80 (1H, s), -10.8 (1H, s),