SUPRAMOLECULAR CHEMISTRY
3
Scheme 1. Structures of the studied calix[6]arene derivatives and corresponding fragmentation pathways.
The salts used in the investigations of complexation of
synthesized ligands were La(NO3)3 × 6H2O, Eu(NO3)3 × 6H2
O, Eu(CF3SO3)3 98%, Yb(NO3)3 × xH2O, (Fluka, p.a. and
Sigma Aldrich, 99.99%). The solvents, acetonitrile (Merck,
Uvasol) and methanol (Merck, Uvasol), were used without
further purification.
71.4, 73.4, 126.9, 128.5, 131.7, 132.2, 132.8, 132.9, 133.3,
145.5, 145.8, 146.0, 146.5, 150.9, 151.9, 152.1, 152.8, 153.3,
154.2, 167.4, 167.7, 168.1, 168.2, 168.6; 1H NMR (DMSO-d6,
300 MHz, 100°C), δ/ppm: 0.70–1.61 (m, 72H, C(CH3)3 and
NHCH2CH3), 2.55–4.83 (m, 36H, ArCH2Ar,OCH2CO, and
NHCH2CH3), 6.47–8.44 (m, 18H, ArH and NH). MS(MALDI
TOF/TOF): m/z = 1483.9524 [M + H]+. (C90H126N6O12, exact
mass = 1483.9512).
Syntheses
Microwave-assisted synthesis of 5,11,17,23,29,35-hexa-
tert-butyl-37,38,39,40,41,42-hexakis-(N-ethyl-N-methyl-car
bamoylmethoxy)calix[6]arene (3)
Microwave-assisted synthesis of 5,11,17,23,29,35-hexa-tert
-butyl-37,38,39,40,41,42-hexakis-[(ethoxycarbonyl)meth-
oxy]calix[6]arene (1)
In 5 cm3 of acetonitrile, 0.25 g of 4-tert-butylcalix[6]
arene (5,11,17,23,29,35-hexa-tert-butylcalix[6]arene-37,
38,39,40,41,42-hexol) (0.25 mmol), 680 μL of 2-bromo-
N-ethyl-N-methylacetamide (3.75 mmol), and 1.04 g of
potassium carbonate (7.50 mmol) were suspended and
stirred for 2 h at 94°C while exposed to microwave
radiation. The organic solvent was evaporated and the
reaction mixture was then extracted with dichloro-
methane/water. The dichloromethane layer was col-
lected and evaporated, and the residue was
recrystallized from acetonitrile to give 282 mg of com-
pound 3 (72% yield).
In 5 cm3 of acetonitrile, 0.39 g of 4-tert-butylcalix[6]arene
(5,11,17,23,29,35-hexa-tert-butylcalix[6]arene-
37,38,39,40,41,42-hexol) (0.40 mmol), 1.01 g of 2-bro-
moethyl acetate (6.03 mmol), and 1.67 g of potassium
carbonate (12.06 mmol) were suspended and stirred for 2
h at 92°C while exposed to microwave radiation. The
organic solvent was evaporated and the reaction mixture
was then extracted with dichloromethane/water. The
dichloromethane layer was collected and evaporated, and
the residue was recrystallized from absolute ethanol to give
560 mg of compound 1 (94% yield). NMR and IR spectra
correspond to the literature data (27).
IR (KBr, ν/cm−1): 2957, 1659, 1481; 1H NMR (CDCl3, 300
MHz, 25°C), δ/ppm: 0.71–1.42 (m, 54H, C(CH3)3), 2.38–4.95
(m, 54H, ArCH2Ar, OCH2CO, NCH2CH3, and NHCH2CH3),
3.32 (s, 18H, NCH3), 6.40–6.76 (m, 4H, ArH), 7.23–7.76 (m,
8H, ArH); 13C NMR (CDCl3, 300 MHz), δ/ppm: 12.4, 12.6,
12.6, 12.6, 13.1, 14.0, 14.0, 14.1, 14.1, 14.2, 31.4, 31.5, 31.6,
31.7, 31.8, 32.6, 32.7, 32.8, 34.0, 34.2, 34.2, 34.3, 34.3, 34.4,
34.4, 34.5, 41.8, 42.2, 42.3, 42.3, 42.4, 43.3, 43.4, 43.6, 43.8,
43.9, 43.9, 70.3, 71.1, 71.9, 123.5, 128.1, 128.4, 128.7, 129.1,
132.3, 132.4, 132.9, 133.3, 133.5, 145.3, 145.7, 146.3, 154.1,
154.9, 167.2, 167.6; 1H NMR (DMSO-d6, 300 MHz, 100°C), δ/
ppm: 0.70–1.61 (m, 54H, C(CH3)3), 2.55–4.83 (m, 60H,
ArCH2Ar, NCH3, NCH2CH3, and NHCH2CH3), 4.23–4.94 (bs,
12H, OCH2CO), 6.19–7.94 (m, 12H, ArH). MS (MALDI TOF/
TOF): m/z = 1569.0530 [M + H]+. (C96H138N6O12, exact
mass = 1569.0529)
5,11,17,23,29,35-hexa-tert-butyl-37,38,39,40,41,42-hexa
kis-(N-ethyl-carbamoylmethoxy)calix[6]arene (2)
In a flask with a stopper, 1.0 g (0.87 mmol) of
55,11,17,23,29,35-hexa-tert-butyl-37,38,39,40,41,42-hexak
is-[(ethoxycarbonyl)methoxy]calix[6]arene (1) was dis-
solved in 7 mL of ethylamine. The resulting solution was
left in a sealed flask at room temperature until TLC analy-
sis showed the disappearance of starting hexaethyl ester
1 (usually requiring 10–14 days). The reaction mixture was
evaporated to dryness, and the residue was triturated
with ethanol, filtered and dried. Compound 2 (983 mg)
was obtained as a white solid (74% yield).
IR (KBr, ν/cm−1): 2959, 1666, 1533, 1475; 1H NMR (CDCl3,
300 MHz, 25°C), δ/ppm: 0.75–1.46 (m, 72H, C(CH3)3 and
NHCH2CH3), 2.28–4.90 (m, 36H, ArCH2Ar,OCH2CO, and
NHCH2CH3), 5.95–8.50 (m, 18H, ArH and NH); 13C NMR
(CDCl3, 300 MHz), δ/ppm: 12.4, 14.5, 14.8, 15.1, 15.4, 29.2,
29.5, 31.2, 31.3, 31.4, 31.5, 31.6, 31.7, 31.8, 34.0, 34.4, 63.3,
Microwave-assisted synthesis of 5,11,17,23,29,35-hexa-
tert-butyl-37,38,39,40,41,42-hexakis-(N,N-diethyl-carbamo
ylmethoxy)calix[6]arene (4)