CuCl2-Specific Metallogels of Pyridyloxalamides in Alcohols
FULL PAPER
N-(l-phenylalanine methyl ester)-N’-(pyridin-4-ylmethyl)oxalamide (3):
Yield: 87%; m.p. 1578C; [a]2D0 =+35 (c=1 in CH2Cl2); 1H NMR
([D6]DMSO): d=9.39 (t, J=6.4 Hz, 1H; CH2NH), 9.01 (d, J=8.4 Hz,
The work reported herein presents a simple system that
shows remarkable metal- and anion-specific gelation proper-
ties and demonstrates how every structural element can be a
determinant.
À
À
1H; CHNHCO), 8.49 (d, J=5.9 Hz, 2H; C Haryl), 7.24 (m, 7H; C HPh
À
and C Haryl), 4.61 (m, 1H; CHa), 4.32 (d, J=6.4 Hz, 2H; CH2NH), 3.65
(s, 3H; OCH3), 3.13 ppm (m, 2H; CH2Ph); 13C NMR ([D6]DMSO): d=
35.8, 41.5, 52.2, 53.7, 122.1, 126.6, 128.2, 129.1, 137.2, 147.4, 149.5, 159.7,
159.8, 171.0 ppm; IR (KBr): n˜ =3303, 1729, 1656, 1521, 1414, 1280 cmÀ1
;
elemental analysis calcd (%) for C15H21N3O4: C 58.62, H 6.89, N 13.67;
found: C 58.72, H 6.90, N 13.67.
Experimental Section
N-(l-leucine methyl ester)-N’-(pyridin-2-ylmethyl)oxalamide (4): Yield:
80%; m.p. 1198C; [a]D20 =À14 (c=1 in CH2Cl2); 1H NMR ([D6]DMSO):
d=9.29 (t, J=5.9 Hz, 1H; CH2NH), 9.06 (d, J=8.3 Hz, 1H; CHNHCO),
Material and methods: All of the solvents were purified and dried by
using standard procedures and distilled prior to use. Melting points were
determined on a Kofler hot-stage apparatus and are uncorrected. 1H and
13C NMR spectra were recorded on a Bruker AV 300 spectrometer.
Chemical shifts (in ppm) are referenced to TMS as an internal standard.
Optical rotations were measured on an Optical Activity AA-10 Automat-
ic Polarimeter in a cell (path length: 1 dm) at 589 nm; concentrations are
given in g/100 mL. Single-reflection attenuated total reflection (SR-ATR)
FTIR spectra were recorded at a resolution of 4 cmÀ1 on an ABB
Bomem MB102 single beam FTIR spectrometer that was equipped with
CsI optics and a DTGS detector for a total of 30 scans by using a hori-
zontal single-reflection ATR diamond prism with a 458 angle of inci-
dence. Each spectrum was recorded as the ratio of the sample spectrum
to the spectrum of the empty ATR plate. Mass spectra were recorded on
an amaZon ETD ion-trap mass spectrometer (Bruker Daltonik, Bremen,
Germany) that was equipped with a standard ESI ion source (nebulizer
pressure: 8 psi; drying gas flow rate: 5 LminÀ1; drying gas temperature:
2508C; potential on the capillary: À4500 V). The compounds were dis-
solved in MeOH and injected into the ESI source by using a syringe
pump at a flow rate of 65 mLminÀ1. The mass spectrometer was operated
in positive polarity mode. Nitrogen was used as the collision gas.
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8.51 (d, J=3.7 Hz, 1H; C Haryl), 7.78 (t, J=7.6 Hz, 1H; C Haryl), 7.28 (d,
À
J=7.6 Hz, 2H; C Haryl), 4.47 (d, J=6.1 Hz, 2H; CH2NH), 4.39 (m, 1H;
CHa), 3.64 (s, 3H; OCH3), 1.74 (m, 3H; CHg and CH2b), 0.89 and
0.86 ppm (2ꢁd, J=5.9 Hz, 6H; CHACHTNUGRTNEUNG
(CH3)2); 13C NMR ([D6]DMSO): d=
21.0, 22.8, 24.3, 38.9, 44.2, 50.5, 52.0, 121.1, 122.2, 136.9, 148.8, 157.2,
159.7, 160.1, 171.9 ppm; IR (KBr): n˜ =3288, 3152, 1749, 1654, 1523, 1395,
1149 cmÀ1; elemental analysis calcd (%) for C15H21N3O4: C 58.62, H 6.89,
N 13.67; found: C 59.02, H 6.89, N 13.67.
N-(l-leucine methyl ester)-N’-(pyridin-3-ylmethyl)oxalamide (5): Yield:
78%; m.p. 1518C; [a]D20 =À15 (c=1 in CH2Cl2); 1H NMR ([D6]DMSO):
d=9.44 (t, J=6.1 Hz, 1H; CH2NH), 9.04 (d, J=8.3 Hz, 1H; CHNHCO),
À
À
8.51 (s, 1H; C Haryl), 8.47 (d, J=4.4 Hz, 1H; C Haryl), 7.69 (d, J=7.7 Hz,
À
À
1H; C Haryl), 7.36 (dd, J=7.7 and 4.9 Hz, 1H; C Haryl), 4.39 (m, 1H;
CHa), 4.35 (d, J=6.3 Hz, 2H; CH2NH), 3.63 (s, 3H; OCH3), 1.68 (m,
3H; CHg and CH2b), 0.88 and 0.84 ppm (2ꢁd, J=5.7 Hz, 6H; CH-
AHCTUNGTRENNUNG
(CH3)2); 13C NMR ([D6]DMSO): d=21.0, 22.8, 24.3, 38.9, 40.2, 50.5, 52.1,
123.5, 134.1, 135.4, 148.3, 149.0, 159.8, 160.1, 171.9 ppm; IR (KBr): n˜ =
3293, 1750, 1652, 1522, 1425, 1205 cmÀ1; elemental analysis calcd (%) for
C15H21N3O4: C 58.62, H 6.89, N 13.67; found: C 58.75, H 6.80, N 13.70.
General procedure for the synthesis of compounds 1–9: A solution of
ethyl oxalyl chloride (9 mmol) in dry CH2Cl2 (20 mL) was added drop-
wise into a mixture of the amino acid methyl ester hydrochloride and
triethylamine (19.2 mmol) or benzylamine (9 mmol) in dry CH2Cl2
(50 mL) over 1 h at 08C and the mixture was stirred for 18 h at room
temperature. The mixture was washed with water (2ꢁ50 mL), a saturated
aqueous solution of ammonium chloride (3ꢁ50 mL), and water again
(2ꢁ50 mL). Then, the organic layer was dried over MgSO4 and evaporat-
ed to obtain oxamic acid ethyl ester as a colorless oil, which was used in
the next step without further purification. Picolylamine (6.5 mmol) and a
catalytic amount of 4-dimethylaminopyridine (DMAP) were added to a
solution of oxamic acid ethyl ester (5.42 mmol) in dry CH2Cl2 (30 mL).
After the mixture was stirred at room temperature for two days, the reac-
tion mixture was purified by column chromatography on silica gel
(CH2Cl2/MeOH, 10:1) to obtain the ligand as a white solid.
N-(l-leucine methyl ester)-N’-(pyridin-4-ylmethyl)oxalamide (6): Yield:
90%; m.p. 1158C; [a]D20 =À15 (c=1 in CH2Cl2); 1H NMR ([D6]DMSO):
d=9.46 (t, J=6.3 Hz, 1H; CH2NH), 9.05 (d, J=8.3 Hz, 1H; CHNHCO),
À
À
8.50 (d, J=5.7 Hz, 2H; C Haryl), 7.25 (d, J=5.7 Hz, 2H; C Haryl), 4.41
(m, 1H; CHa), 4.36 (d, J=6.5 Hz, 2H; CH2NH), 3.64 (s, 3H; OCH3),
1.68 (m, 3H; CHg and CH2b), 0.88 and 0.86 ppm (2ꢁd, J=6.0 Hz, 6H;
CHACTHNUTRGNEUNG
(CH3)2); 13C NMR ([D6]DMSO): d=21.0, 22.8, 24.3, 38.9, 41.5, 50.6,
52.1, 122.2, 147.4, 149.6, 159.9, 160.0, 171.9 ppm; IR (KBr): n˜ =3292,
1748, 1650, 1522, 1210, 1155 cmÀ1; elemental analysis calcd (%) for
C15H21N3O4: C 58.62, H 6.89, N 13.67; found: C 59.15, H 6.79, N 13.70.
Acknowledgements
N-(l-phenylalanine methyl ester)-N’-(pyridin-2-ylmethyl)oxalamide (1):
Yield: 82%; m.p. 1348C; [a]2D0 =+41 (c=1 in CH2Cl2); 1H NMR
([D6]DMSO): d=9.23 (t, J=6.0 Hz, 1H; CH2NH), 9.03 (d, J=8.4 Hz,
We thank Dr. Zimmermann for performing the FTIR measurements and
´
Dr. Kazazic for performing the MS (ESI) analysis. Financial support
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1H; CHNHCO), 8.49 (d, J=4.6 Hz, 1H; C Haryl), 7.76 (t, J=7.7 Hz, 1H;
from the Croatian Ministry of Science, Education, and Sports (Project
Nos 098-0982904-2912 and 119-1193079-1084) is gratefully acknowledged.
M.C. thanks the Progetto per Giovani Ricercatori “Rita Levi Montalcini”
2009.
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C Haryl), 7.25 (m, 7H; C HPh and C Haryl), 4.62 (m, 1H; CHa), 4.42 (d,
J=6.2 Hz, 2H; CH2NH), 3.66 (s, 3H; OCH3), 3.29 ppm (m, 2H; CH2Ph);
13C NMR ([D6]DMSO): d=35.8, 44.2, 52.2, 53.7, 121.0, 122.3, 126.6,
128.3, 129.1, 136.7, 137.3, 148.9, 157.2, 159.6, 159.8, 171.1 ppm; IR (KBr):
n˜ =3317, 3284, 1738, 1655, 1508, 1434, 1251 cmÀ1; elemental analysis calcd
(%) for C15H21N3O4: C 58.62, H 6.89, N 13.67; found: C 58.47, H 6.95,
N 13.69.
[1] a) J.-M. Lehn, Supramolecular Chemistry, Wiley-VCH, Weinheim,
1995; b) J. W. Steed, J. L. Atwood, Supramolecular Chemistry, Wiley,
Hoboken, 2009; c) P. A. Gale, J. W. Steed, Supramolecular Chemis-
try: From Molecules to Nanomaterials, Wiley-VCH, Weinheim, 2012.
[2] a) Molecular Gels: Materials with Self-Assembled Fibrillar Networks
(Ed.: R. G. Weiss, P. Terech), Springer, Dordrecht, 2005; b) F. Fages,
Top. Curr. Chem. 2005, 256, 1; c) D. K. Smith, Molecular Gels-Nano-
structured Soft Materials in Organic Nanostructures (Ed.: J. L.
Atwood, J. W. Steed), Wiley-VCH, Weinheim, 2008.
N-(l-phenylalanine methyl ester)-N’-(pyridin-3-ylmethyl)oxalamide (2):
Yield: 80%; m.p. 1958C; [a]2D0 =+35 (c=1 in CH2Cl2); 1H NMR
([D6]DMSO): d=9.36 (t, J=6.3 Hz, 1H; CH2NH), 9.00 (d, J=8.4 Hz,
À
À
1H; CHNHCO), 8.46 (m, 2H; C Haryl), 7.63 (d, J=7.8 Hz, 1H; C Haryl),
À
À
7.35 (dd, 1H, J=7.7 and 4.8 Hz; C Haryl), 7.23 (m, 5H; C HPh), 4.59 (m,
1H; CHa), 4.31 (d, J=6.3 Hz, 2H; CH2NH), 3.64 (s, 3H; OCH3),
3.12 ppm (m, 2H; CH2Ph); 13C NMR ([D6]DMSO): d=35.8, 40.1, 52.1,
53.6, 123.5, 126.6, 128.2, 129.0, 134.1, 135.2, 137.2, 148.3, 148.9, 159.6,
159.8, 171.0 ppm; IR (KBr): n˜ =3290, 1734, 1655, 1522, 1435, 1257 cmÀ1
;
elemental analysis calcd (%) for C15H21N3O4: C 58.62, H 6.89, N 13.67;
found: C 58.49, H 6.97, N 13.55.
Chem. Eur. J. 2013, 19, 5411 – 5416
ꢀ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
5415