Acknowledgements
We thank the Spanish MICINN Project CTQ2006-15672-C05-01
for financial support, and SCSIE of the University for provision
of the X-ray crystallographic facilities.
Notes and references
‡ Data collection of crystals of 2 and 3 was performed at 293 K on a
Nonius Kappa-CCD single crystal diffractometer using Mo Ka radiation
˚
(l = 0.7173 A). The crystal structures were solved with the program
Sir-97 (see ref. 17). Anisotropic least-squares refinement was carried out
with SHELXL-97 (see ref. 18). Crystal data for 2: C17H23N3O4, Mw
=
333.39 g mol-1, monoclinic, space group P21/n, a = 16.2750(8), b =
3
˚
5.7027(2), c = 20.1112(10), b = 100.273(3), V = 1836.63 (14) A , Z =
4, 6339 measured reflections, 3771 unique reflections, Rint = 0.0656, 220
parameters, R1 (all data) = 0.2209, R1[I > 2s(I)] = 0.063, wR2 (all data) =
0.3011, wR2[I > 2s(I)] = 0.1837. Crystal data for 3: C19H27N3O6, Mw
=
393.44 g mol-1, monoclinic, space group P21/n, a = 13.1760(4), b =
3
˚
5.4360 (2), c = 29.7130(10), b = 99.289(2), V = 2100.28(13) A , Z =
4, 6300 measured reflections, 3791 unique reflections, Rint = 0.0488, 258
parameters, R1 (all data) = 0.1286, R1[I > 2s(I)] = 0.0513, wR2 (all data) =
0.1827, wR2[I > 2s(I)] = 0.1399.
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Fig. 3 View along the b-axes showing the hydrogen bond pattern (dotted
lines) of crystal structures of 1–(+)-AMPH (A), 2 (B) and 3 (C).
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˚
˚
benzene rings of the drugs are 3.04 A in 2 and 3.43 A in 3, they
are shifted with respect to the distances between their respective
˚
˚
centroids, 5.44 A and 5.70 A for 2 and 3, respectively. Although
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pyrazolate nitrogens as found in helices 2 and 3 (Figs 1 and 2,
left, and Fig. 3 in which a view along the b-axis is shown for 1, 2
and 3).
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stacking of the aromatic groups of the drug. Another difference
is the short contacts between the helices in the crystal packing.
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double-stranded helices were well separated in the crystal, in 2
and 3 the packing is much tighter. Nevertheless, these crystal
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Other interactions modulate the type of hydrogen-bonding
acceptor groups and the external shape of the supramolecular
assembly. Therefore, this structural type might be almost general
for any primary ammonium group interacting with such pyrazo-
late units. Currently we are exploring these points and studying
the extent of preservation of these helical structures in solvents of
low or medium polarity.
18 G. M. Sheldrick, Acta Crystallogr., Sect. A: Found. Crystallogr., 2007,
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3214 | Org. Biomol. Chem., 2009, 7, 3212–3214
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