Intramolecular hypervalent CO...S interactions in a series of 1,3-benzothiazole derivatives

Article abstract of DOI:10.1039/c1ce06106b

Seven compounds derived from 2-(4-chlorophenoxy)-2-methylpropionic acid and 2-aminobenzothiazole, 2-amino-6-methylbenzothiazole, 2-amino-6- methoxybenzothiazole, 2-amino-6-ethoxybenzothiazole, 2-amino-6- chlorobenzothiazole, 2-amino-6-nitrobenzothiazole, and 2-amino-6- (methylsulfonyl) benzothiazole have been prepared and structurally characterized. This set of 1,3-benzothiazole derivatives (1-7) has been studied by means of elemental analysis, mass spectrometry, IR, NMR (¹H, ¹³C) spectroscopy, and single-crystal X-ray diffraction analysis. This work focuses on the description of the hypervalent contacts (CO...S, S...S), hydrogen bonds Y-H...X (Y = O, N, C; X = O, N, Cl, π) and van der Waals contacts (Cl...π, S...π, H...H) that are found to be the driving forces for the supramolecular arrangements present in the crystal structures.

Full text of DOI:10.1039/c1ce06106b

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PAPER
Intramolecular hypervalent C]O/S interactions in a series of
1,3-benzothiazole derivatives†
a
Gabriel Navarrete-Vazquez, Alfredo Alaniz-Palacios,a Margarita Tlahuextl,b Margarita Bernal-Uruchurtuc
and Hugo Tlahuext
*
ꢀ
*
c
Received 28th August 2011, Accepted 25th October 2011
DOI: 10.1039/c1ce06106b
Seven compounds derived from 2-(4-chlorophenoxy)-2-methylpropionic acid and
2-aminobenzothiazole, 2-amino-6-methylbenzothiazole, 2-amino-6-methoxybenzothiazole, 2-amino-
6-ethoxybenzothiazole, 2-amino-6-chlorobenzothiazole, 2-amino-6-nitrobenzothiazole, and 2-amino-
6-(methylsulfonyl) benzothiazole have been prepared and structurally characterized. This set of
1,3-benzothiazole derivatives (1–7) has been studied by means of elemental analysis, mass
spectrometry, IR, NMR (1H, 13C) spectroscopy, and single-crystal X-ray diffraction analysis. This
work focuses on the description of the hypervalent contacts (C]O/S, S/S), hydrogen bonds
Y–H/X (Y ¼ O, N, C; X ¼ O, N, Cl, p) and van der Waals contacts (Cl/p, S/p, H/H) that
are found to be the driving forces for the supramolecular arrangements present in the crystal
structures.
intermolecular interaction. Being specific and highly direc-
1. Introduction
tional, hydrogen bonds promote the optimal geometrical
arrangement of the different synthons found in crystal struc-
tures. In recent times weak interactions such as C–H/X (X ¼
O, N, S, F, Cl, Br, I), C–H/p and p/p contacts have been
identified as an important driving force on the stabilization of
molecular solids.2 In the same way, hypervalent interactions,
X/X or X/Y, may form robust supramolecular synthons
with many features in common with organic hydrogen bonds,
including the ability to form polymeric networks in the solid
state.3 Additionally, C–H/X hydrogen bonds have great
importance for molecular recognition processes,4 the reactivity
and structure of biomolecular species,5 the stabilization of
inclusion complexes,6 conformational isomerism7 and the
properties of ionic liquids.8
The aim of crystal engineering is to establish connections
between molecular and supramolecular structure on the basis of
non-covalent intra- and intermolecular interactions. The forces
resulting from these interactions range from very weak to strong
and depend on several properties of the interacting individual
molecules. In most cases they are cooperative, thus their
combined effect on the crystal structure is hard to evaluate from
each single interaction present in the system. It would be very
convenient to identify substructural units (supramolecular syn-
thons) in a target supramolecule and assemble it from logically
chosen precursor molecules.1 However, the final outcome of
multiple interactions in a system has proven to be difficult to
anticipate due to the subtleties governing non-covalent
interactions.
The seven molecules studied here are hybrid amides from
clofibric acid and 1,3-benzothiazole pharmacophore, related to
antidiabetic activity.9 Fibrates (phenoxyisobutyrates) such as
bezafibrate, clofibrate and fenofibrate are used as therapeutic
agents in the treatment of dyslipidemia, heart disease and dia-
betic complications in humans. The fibrates are a widely used
class of lipid-modifying agents that decrease plasma triglycer-
ides.10 The fibrate pharmacophore has been of interest to
medicinal chemists ever since the initial discovery that ethyl
chlorophenoxyisobutyrate (clofibrate, a prodrug, that is bio-
transformed into clofibric acid) possessed hypolipidemic
properties.11
Hydrogen bonding is a classical example of a strong or
moderate, but generally specific and highly directional,
aFacultad de Farmacia, Universidad Autoꢀnoma del Estado de Morelos, Av.
Universidad 1001, Col. Chamilpa, C.P. 62209 Cuernavaca, Morelos,
Meꢀxico. E-mail: gabriel_navarrete@uaem.mx
bCentro de Investigaciones Quꢀımicas, Universidad Autoꢀnoma del Estado de
Hidalgo, Carretera Pachuca-Tulancingo Km 4.5 U. Universitaria, C.P.
ꢀ
42184 Mineral de la Reforma, Hidalgo, Mexico
cCentro de Investigaciones Quꢀımicas, Universidad Autoꢀnoma del Estado de
Morelos, Av. Universidad 1001, Col. Chamilpa, C.P. 62209 Cuernavaca,
ꢀ
Morelos, Mexico. E-mail: tlahuext@ciq.uaem.mx
† Electronic supplementary information (ESI) available: Thermal
displacement plots for compounds 1–7. CCDC reference numbers
827868–827874. For ESI and crystallographic data in CIF or other
electronic format see DOI: 10.1039/c1ce06106b
In order to assist our knowledge about the electronic and steric
requirements from these kinds of molecules to show anti-
hyperlipidemic activity, we have designed, synthesized and
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acetone–water (2 : 1) mixture.‡ Selected bond lengths, torsion
angles, and intramolecular hypervalent contacts are given in
Table 1 and hydrogen bonding parameters are given in Table 2.
The seven independent molecular systems have some common
features. All crystal structures showed two kinds of intra-
molecular interactions: one N–H/O–C hydrogen-bond that can
be described by the graph set S(5)14 and an hypervalent C]O/S
contact (Tables 1 and 2).15
Scheme 1 Molecular structures of compounds 1–7.
This presumably sets the stage for the intermolecular interac-
tions observed in the crystal networks. These intramolecular
cooperative interactions provide essentially planar 1,3-benzo-
thiazole moieties, with the N1–C8–C7 side chain deviating only
slightly from the plane of the benzothiazole group; the C11–N1–
C8–C7 torsion angle values are in the range of 169.1(2)–177.9
(2)ꢁ. The 4-chlorophenyl rings are synclinal to the C]O groups
in compounds 1 and 2 with C8–C7–O1–C1 torsion angles of 73.5
(3) and 74.0(3)ꢁ, respectively, and antiperiplanar in compounds
3–7; the C8–C7–O1–C1 torsion angle values are in the range of
156.2(2)–179.2(1)ꢁ. The N1–C8 and N1–C11 bond lengths are
intermediate between single and double bond length, indicative
of electronic delocalization in the O2–C8–N1–C11 region.
However, the O2–C8 distances are not significantly longer than
the expected distances for C]O bonds (Table 1).16
determined the crystal structures of a series of 1,3-benzothiazole
derivatives 1–7 (Scheme 1).
The structural differences found in this family of compounds
emphasize the influence that small chemical and electronic
modifications on the molecular level have on the 3D arrangement
in the solids. In this respect it is interesting to note that these
seven crystal structures share only two kinds of cooperative
intramolecular interactions: an intramolecular hydrogen bond
N–H/O–C that can be described by the graph S(5), and an
intramolecular hypervalent C]O/S contact. These interactions
govern the molecular conformation and lead to six different
synthons.
The hypervalent C]O/S contacts in all systems are within
ꢁ
the 2.648(1)–2.788(2) A range, considerably smaller than the sum
2. Results and discussion
ꢁ
of the van der Waals radii (3.32 A); the C13–S1/O2 and C8–
2.1 Syntheses and spectroscopic characterization
O2/S1 angles are in the 157–162ꢁ and 95–98ꢁ range, respec-
tively, consistent with hypervalent interactions (Table 1).15
In all compounds was observed the formation of N–H/X
(1, 2, 3 and 5, X ¼ O; 4 and 6, X ¼ Cl; 7, X ¼ N) hydrogen bond
Compounds 1–7 were obtained in yields ranging from 25 to
60% by combination of 2-(p-chlorophenoxy)-2-methyl-
propionic acid with 2-aminobenzothiazole, 2-amino-6-methyl-
benzothiazole, 2-amino-6-methoxybenzothiazole, 2-amino-6-
ethoxybenzothiazole, 2-amino-6-chlorobenzothiazole, 2-amino-
6-nitrobenzothiazole, and 2-amino-6-(methylsulfonyl)benzo-
thiazole in dichloromethane as solvent. The compounds 1–7 have
been characterized by means of elemental analysis, mass spec-
trometry, IR, and NMR (1H, 13C) spectroscopy, and single-
crystal X-ray diffraction.
‡ Crystal data for 1–7: C17H15ClN2O2S 1, M ¼ 346.82, orthorhombic,
ꢁ
space group Pbca, a ¼ 12.097(3), b ¼ 10.088(2), c ¼ 26.807(6) A, a ¼
ꢁ
3
ꢁ
b ¼ g ¼ 90 , V ¼ 3271.3(13) A , T ¼ 100 K, Z ¼ 8. 27083 reflections
measured, 2868 unique (Rint ¼ 0.054) and 2830 with I > 2s(I). The
final R values were R1 ¼ 0.053 and wR2 (all data) ¼ 0.103. CCDC
827868. C18H17ClN2O2S 2, M ¼ 360.85, orthorhombic, space group
ꢁ
Pbca, a ¼ 14.1449(13), b ¼ 9.9181(9), c ¼ 25.167(2) A, a ¼ b ¼ g ¼
ꢁ
3
ꢁ
90 , V ¼ 3530.7(6) A , T ¼ 100 K, Z ¼ 8. 23225 reflections measured,
3109 unique (Rint ¼ 0.044), 3035 with I > 2s(I). The final R values
The formation of the compounds 1–7 could be evidenced
directly from the IR and 13C NMR spectra. The IR spectra
showed bands in the range from 1617 to 1697 cmꢀ1 and 1574 to
1604 cmꢀ1 that are typical for the vibrations of the N–C]O and
C]N groups, respectively.12 The 13C NMR signals of the amide
and imine carbon atoms (NC]O, N]C) are found in the range
of dC 173.0–173.8 and 156.5–161.8 ppm, respectively.13 The
chemical shifts of the carbon atoms in the 6-substituted-2-ami-
nobenzothiazole moieties were modulated by the inductive effect
of the substituent on C6 (see the Experimental part).
were R1
¼
0.062 and wR2 (all data)
¼
0.12. CCDC 827869.
C19H21ClN2O4S 3, M ¼ 408.89, monoclinic, space group P2(1)/n, a ¼
ꢁ
ꢁ
14.9642(18), b ¼ 7.7170 (9) c ¼ 17.958(2) A, b ¼ 111.457(2) , V ¼
3
ꢁ
1930.1 (4) A , T ¼ 173 K, Z ¼ 4. 17913 reflections measured, 3394
unique (Rint ¼ 0.040), 2816 with I > 2s(I). The final R values were R1
¼ 0.037 and wR2 (all data) ¼ 0.102. CCDC 827870. C19H19ClN2O3S 4,
M ¼ 390.87, monoclinic, space group P2(1)/c, a ¼ 23.731(2), b ¼
ꢁ
3
ꢁ
ꢁ
13.7198 (14), c ¼ 17.4841(18) A, b ¼ 102.160(2) , V ¼ 5564.7 (10) A ,
T ¼ 100 K, Z ¼ 12. 53185 reflections measured, 9817 unique (Rint
¼
0.055), 8003 with I > 2s(I). The final R values were R1 ¼ 0.041 and
wR2 (all data) ¼ 0.099. CCDC 827871. C18H18Cl2N2O3S 5, M ¼
1
ꢂ
The H NMR signals of the amide hydrogen atoms (N–H)
413.30, triclinic, space group P1, a ¼ 7.2962(7), b ¼ 9.8387(10), c ¼
ꢁ
ꢁ
13.9567(14) A, a ¼ 77.188(2), b ¼ 84.710(2), g ¼ 76.498(2) , V ¼
were found in the range of dH 9.90 to 10.34 ppm. The mass
spectra (FAB+) showed the peak for the molecular ions at m/z
347 (70%) for compound 1, 361 (100%) for compound 2, 377
(70%) for compound 3, 391 (100%) for compound 4, 381 (70%)
for compound 5, 392 (20%) for compound 6, and 425 (100%) for
compound 7.
3
ꢁ
949.08(16) A , T ¼ 173 K, Z ¼ 2. 9171 reflections measured, 3333
unique (Rint ¼ 0.032), 3093 with I > 2s(I). The final R values were R1
¼ 0.031 and wR2 (all data) ¼ 0.085. CCDC 827872. C17H14ClN3O4S 6,
ꢂ
M ¼ 391.82, triclinic, space group P1, a ¼ 7.395(2), b ¼ 7.653(2), c ¼
ꢁ
ꢁ
15.958(4) A, a ¼ 90.156(5), b ¼ 96.693(4), g ¼ 99.998(4) , V ¼ 883.0
3
ꢁ
(4) A , T ¼ 294 K, Z ¼ 2. 8330 reflections measured, 3097 unique (Rint
¼ 0.030), 2344 with I > 2s(I). The final R values were R1 ¼ 0.042 and
wR2 (all data) ¼ 0.133. CCDC 827873. C18H17ClN2O4S2 7, M ¼
424.91, monoclinic, space group C2/c, a ¼ 29.002(3), b ¼ 8.6295(9), c
ꢁ
3
2.2 X-Ray crystal structures
ꢁ
ꢁ
¼ 16.5593(18) A, b ¼ 113.948(2) , V ¼ 3787.5(7) A , T ¼ 294 K, Z ¼
8. 17796 reflections measured, 3338 unique (Rint ¼ 0.038), 2688 with I
> 2s(I). The final R values were R1 ¼ 0.039 and wR2 (all data) ¼ 0.12.
CCDC 827874.
Single crystals were grown at room temperature; 1, 2, 3, 5 from
methanol solution; 4, 7 from ethanol solution and 6 from an
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Table 1 Selected bond lengths, torsion angles, and intramolecular hypervalent contacts for compounds 1–7
C7–C8–N1–C11/ꢁ
C8–C7–O1–C1/ꢁ
S1/O2/A
C13–S1/O2/ꢁ
S1/O2]C8/ꢁ
ꢁ
C8]O2/A
ꢁ
N1–C8/A
ꢁ
N1–C11/A
ꢁ
Compound
1
2
3
4a
4ba
4cb
5
6
7
1.219(3)
1.229(4)
1.218(2)
1.218(3)
1.217(2)
1.223(3)
1.220(2)
1.210(3)
1.218(3)
1.359(3)
1.356(4)
1.358(3)
1.350(3)
1.356(3)
1.354(3)
1.367(2)
1.354(3)
1.355(3)
1.384(3)
1.385(4)
1.383(3)
1.382(3)
1.381(3)
1.382(3)
1.378(2)
1.384(3)
1.385(3)
169.1(2)
176.3(3)
173.4(2)
ꢀ177.9(2)
ꢀ174.5(2)
ꢀ174.4(2)
ꢀ171.1(1)
ꢀ175.0(2)
ꢀ169.9(2)
73.5(3)
74.0(3)
2.696
2.758
2.709
2.774
2.787
2.788
2.648
2.745
2.778
159.4
161.2
161.6
161.1
161.3
161.1
162.8
160.6
157.3
97.5
96.2
97.1
95.0
94.8
94.8
98.1
96.0
95.7
177.4(2)
171.2(2)
171.3(2)
178.5(2)
ꢀ179.2(1)
ꢀ156.2(2)
ꢀ161.1(2)
a
Data belong to: C27]O5, C27–N3, C30–N3, C26–C27–N3–C30, C27–C26–O4–C20, S2/O5, C32–S2/O5, S2/O5]C27. b Data belong to: C46]
O8, C46–N5, C49–N5, C45–C46–N5–C49, C46–C45–O7–C39, S3/O8, C51–S3/O8, S3/O8]C46.
that, in addition to being an intramolecular organizer, acts as
a three center or bifurcated interaction.17 In addition to the
intermolecular N–H/X bond, other hydrogen bonds Y–H/X
(Y ¼ O, C; X ¼ O, N, Cl, p) and van der Waals contacts (Cl/p,
S/p, H/H) are found as the contributing forces for the
supramolecular arrangements in the crystal structures.
In the packing of compounds 1 and 2 the intermolecular
hydrogen bonds N–H/O]C link molecules into chains running
along the b axis. This bond is shorter than the intramolecular one
(Fig. 1 and Table 2).
Table 2 Hydrogen-bond geometries (A, ꢁ) for compounds 1–7
ꢁ
The adjacent chains in 1 are connected through C–H/p and
C–H/N interactions. It is possible to see that these latter lead to
a 2D undulating network parallel to plane ab (Table 2 and
Fig. 2a and b). In the C–H/p van der Waals contact the
D–H/A
D–H H/A D/A D–H/A Symmetry codes
Compound 1
N1–H1/O1
N1–H1/O2
C10–H10B/N2 0.98 2.59 3.524(4) 159
C14–H14/C16 0.95 2.79 3.557(4) 137
Compound 2
N1–H1/O1
N1–H1/O2
C14–H14/Cl1 0.95 2.91 3.682(3) 139
C17–H17/Cl1 0.95 2.84 3.697(3) 151
C4–Cl1/p
Compound 3
N1–H1/O1
N1–H1/O4
O4–H6A/N2 0.84 2.13 2.888(2) 151
C3–H3/O3 0.95 2.62 3.261(2) 125
C14–H14/O3 0.95 2.71 3.406(3) 131
C9–H9A/O2 0.98 2.47 3.448(3) 175
C16–H16/p
0.86 2.37 2.714(3) 104
0.86 2.09 2.918(3) 163
1
1
ꢁ
distance C14/Cg (C12–C17) is 4.52 A, and the shortest carbon–
/
ꢀ x, ꢀ /2 + y, z
2
1
/
ꢀ x, 1/2 + y, z
18b,e,f
ꢁ
carbon distance is 3.547(4) A.
2
ꢀ /2 ꢀ x, 1/2 + y, z
1
In the crystal structure of 2, in addition to the aforementioned
interactions, the neighboring chains also are associated through
two weak C–H/Cl hydrogen bonds and Cl/p contacts leading
to an overall 3D network (Table 2).19 Of these, the C–H/Cl
distance between the ring centroid Cg (C12–C17) and the Cl(1)
0.86 2.45 2.740(3) 100
0.86 2.07 2.909(4) 165
1
1
/
2
ꢀ x, ꢀ /2 + y, z
ꢀx, 1 ꢀ y, ꢀz
ꢀx, ꢀy, ꢀz
1
1
1.75 3.36 5.11
178
x, /2 ꢀ y, ꢀ /2 + z
19e
ꢁ
atom is 3.362 A (Fig. 3). Of these, the C–H/Cl interactions
link three neighboring molecules forming cyclic motifs (I and II)
0.86 2.14 2.516(2) 106
0.86 2.04 2.874(2) 162
1 ꢀ x, 1 ꢀ y, 1 ꢀ z
1 + x, y, z
that belong to the graph set R2 (28) (Fig. 3).14 Additionally, the
2
packing is stabilized by Cl/p contacts. The distance between the
ꢁ
ring centroid Cg (C12–C17) and the Cl(1) atom is 3.362 A
(Fig. 3).19e
1
ꢀx, ꢀ /2 + y, 1/2 ꢀ z
1
1 ꢀ x, 1/2 + y, /2 ꢀ z
0.95 3.14 3.78
127
124
1 ꢀ x, 1 ꢀ y, 1 ꢀ z
1
C18–H18C/p 0.98 2.78 3.43
Compound 4
ꢀx, ꢀ /2 + y, 1/2 ꢀ z
N1–H1A/O1 0.86 2.07 2.511(2) 111
N3–H3A/O4 0.86 2.01 2.492(2) 114
N5–H5A/O7 0.86 2.03 2.498(2) 113
C14–H14/O5 0.95 2.57 3.409(3) 148
N3–H3A/Cl2 0.86 2.72 3.464(2) 146
N5–H5A/Cl1 0.86 2.74 3.441(2) 140
C16–H16/Cl2 0.95 2.77 3.599(2) 146
ꢀx, ꢀy, 1 ꢀ z
1 ꢀ x, 1 ꢀ y, ꢀz
ꢀx, 1 ꢀ y, 1 ꢀ z
ꢀx, 1 ꢀ y, 1 ꢀ z
C19–H19C/p 0.98 3.03 3.61
Compound 5
119
N1–H1/O1
N1–H1/O3
O3–H3A/N2 0.84 2.11 2.874(2) 152
C9–H9C/Cl1 0.98 2.94 3.856(2) 157
C14–H14/O2 0.95 2.52 3.263(2) 135
0.86 2.14 2.542(2) 110
0.86 2.04 2.873(2) 161
1 ꢀ x, ꢀy, 1 ꢀ z
1 + x, y, z
1 ꢀ x, ꢀ1 ꢀ y, 2 ꢀ z
1 ꢀ x, 1 ꢀ y, 1 ꢀ z
ꢀx, ꢀy, 1 ꢀ z
C16–H16/p
Compound 6
0.95 3.24 3.87
125
N1–H1A/O1 0.86 2.04 2.508(3) 113
N1–H1A/Cl1 0.86 2.83 3.602(2) 151
C14–H14/O2 0.93 2.59 3.361(3) 140
Compound 7
ꢀx, 2 ꢀ y, ꢀz
ꢀx, 1 ꢀ y, 1 ꢀ z
N1–H1/O1
N1–H1/N2
C10–H10A/O4 0.96 2.58 3.400(3) 144
C17–H17/O3 0.93 2.67 3.487(3) 147
0.86 2.14 2.553(3) 109
0.86 2.25 3.073(3) 159
Fig. 1 View of the bifurcated hydrogen bonds (N–H/O) and hyper-
valent contacts (C]O/S)—dashed lines—generating chains along the
b axis in compound 2. For clarity, methyl groups and hydrogen atoms not
involved in the hydrogen-bonding interactions were omitted.
2 ꢀ x, y, 3/2 ꢀ z
2 ꢀ x, 1 ꢀ y, 1 ꢀ z
x, 1 ꢀ y, 1/2 + z
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Fig. 2 (a) View of two adjacent chains in the crystal structure of 1,
showing the 2D undulating network parallel to the plane ab and their
association with C–H/N and C–H/p hydrogen-bonding; methyl and
chlorophenyl groups, and hydrogen atoms not involved in the hydrogen-
bonding interactions were omitted for clarity. (b) Lateral view of the 2D
undulated network.
Fig. 4 Supramolecular synthons 3a and 5a, showing their association
with N–H/O–H/N and C–H/p interactions. Hydrogen atoms not
involved in the hydrogen-bonding interactions were omitted for clarity.
Solvent forms part of the crystal structure of compounds 3 and
5 in which the asymmetric units contain one molecule of meth-
anol acting both as donor and acceptor of H-bonds (Table 2).
The crystal structures of 3 and 5 show that neighboring mole-
cules are coupled through N–H/OM–H/N links (OM is the
oxygen atom of the methanol molecule) and C–H/p interac-
tions, thus generating the supramolecular synthons 3a and 5a
that possess crystallographic inversion symmetry (Fig. 4).17,18,20
The 3D and 2D networks observed in the packing of these
synthons suggest that some stereoelectronic effects of the
substituents on C15 (CH3–O for compound 3 and Cl for
compound 5) might play a role in modulating the final packing.
In the crystal packing of 3, the adjacent synthons 3a are con-
nected together by C–H/O and C–H/p hydrogen bonds
inducing an overall 3D network (Fig. 5).
Fig. 3 Fragment of the 3D hydrogen-bonded network for compound 2,
showing the Cl/p contacts and cyclic motifs I and II generated by C–
H/Cl interactions. Methyl groups and hydrogen atoms not involved in
the hydrogen-bonding interactions were omitted for clarity.
Fig. 5 Fragment of the crystal packing of 3, showing the 3D network
generated by C–H/O and C–H/p interactions between the 3a syn-
thons. Methyl groups and hydrogen atoms not involved in the hydrogen-
bonding interactions were omitted for clarity.
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Fig. 7 Fragment of the crystal structure of compound 4, showing the
assembly of the synthons I–III through cooperative C–H/O, C–H/Cl,
N–H/Cl, C–H/p and offset p/p interactions. H atoms not involved
in the hydrogen-bonding interactions were omitted for clarity.
Fig. 6 Fragment of the crystal structure of compound 5, showing the 2D
network generated by C–H/Cl, C–H/O and Cl/p interactions
between the 5a synthons. Methyl groups and hydrogen atoms not
involved in the hydrogen-bonding interactions were omitted for clarity.
Synthons II assemble using C–H/O and C–H/Cl interactions
involving the 6-ethoxybenzothiazole H atoms on C14 and C16 of
molecule 4a. These interactions lead to synthon III, described by
4
the graph set R4 (28). Due to the distance found between the
methyl H atoms on C19 of molecule 4a and the 4-chlorophenoxy
ꢁ
group of molecule 4b, 3.62 A, it is possible that the packing is
The oxygen atom of the methoxy group (CH3–O–Ar) is an
acceptor of two H atoms. These H atoms are donated by the
carbon atoms C3 and C14. Thus, the C3–H3/O3 contacts
generate chains that run along the a axis. These chains are con-
nected by C14–H14/O3, C9–H9A/O2 contacts and facial
hydrogen bonds (ArOCH3/p) producing the overall 3D
network. The separation of the methyl group (C18) and the aryl
further stabilized by these C–H/p interactions. The N–H/Cl
hydrogen bond between molecules 4c and 4a is further stabilized
by an offset p/p interaction between 4a and 4c, with a distance
between the ring centroids Cg1 and Cg3 (centroids of adjacent
ꢁ
4-chlorophenoxy groups in molecules 4a and 4c) of 3.76 A.
Compound 6 has a singular interaction pattern that differen-
tiates it from the other six members of the family. The crystal
structure shows that two adjacent molecules are interconnected
through C–H/O interactions and O/S/S trifurcated hyper-
valent contacts that generate the synthon I with crystallographic
inversion symmetry.15h In this intermolecular hypervalent inter-
18
ꢁ
centroid Cg (C12–C17) is 3.433 A (Fig. 5 and Table 2).
The crystal packing of 5 shows that the adjacent synthons 5a
are interconnected by weak hydrogen bonds C14–H14/O2, C9–
H9C/Cl1 and Cl/p contacts generating a 2D network, in
which it is possible to observe the chlorine atom bonded to the
aryl group (Cl1) being a better donor/acceptor than the chlorine
atom attached to the benzothiazole group (Cl2).18,19 The motifs
ꢁ
action the O/S and S/S distances are 3.298(2) and 3.494(1) A,
respectively, the former being only slightly smaller than the sum
ꢁ
of the van der Waals radii of these centers (O/S ¼ 3.32 A, S/S
2
2
6
R2 (16), R2 (18) and R6 (24) (I–III) can be identified (Fig. 6).
ꢁ
¼ 3.6 A) suggesting that its role in the stability of this synthon is
2
2
The motifs R2 (16) and R2 (18) are further stabilized by
intramolecular hypervalent S/O interactions and van der Waals
Cl/p contacts, respectively. The distance between the ring
only marginal but probably contributing through cooperative
effects.15
ꢁ
centroid Cg and the Cl(1) atom is 3.546 A. On the other hand, the
transannular Cl1/Cl10 and Cl2/Cl20 distances in the motif
6
R6 (24) are 8.842(1) and 5.937(1) A, respectively.
ꢁ
Fig. 7 shows the crystal packing of compound 4. The asym-
metric unit contains three independent molecules (4a, 4b, 4c).
From the hydrogen-bond pattern, the supramolecular synthons I
and II that possess crystallographic inversion symmetry can be
distinguished. The synthon I is generated by coupling of two
adjacent 4b molecules through N–H/Cl hydrogen bonds; the
N–H group is also involved in the previously described intra-
molecular bifurcated H-bond. I is further stabilized by offset p/
p interactions, with a distance between the ring centroids Cg2
0
ꢁ
and Cg2 (centroids of the 4-chlorophenoxy groups) of 3.66 A.
The synthon II is generated by the C–H/O hydrogen bonds
between two 4c molecules in which the acceptor oxygen atom is
also involved in the intramolecular hypervalent O/S contact.
Synthons I and II are further interconnected by the molecule
4a through C–H/O, C–H/Cl, N–H/Cl, C–H/p and offset
p/p interactions to give an overall 2D network (Table 1).18,19
Fig. 8 Fragment of the crystal structure of compound 6, showing the
motifs I–III generated by N–H/Cl hydrogen bonds, p/p interactions
and H/H van der Waals contacts. Methyl groups and hydrogen atoms
not involved in the hydrogen-bonding interactions were omitted for
clarity.
1260 | CrystEngComm, 2012, 14, 1256–1263
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ppm and Hz, respectively. Standard reference was used: TMS (dH
¼ 0 and dC ¼ 0). IR spectra have been recorded on a Bruker
Vector 22 FT spectrophotometer. Mass spectra were obtained on
a Jeol JMS 700 mass spectrometer. Elemental analyses have been
carried out on an Elementar Vario ELIII instrument.
3.2 Synthesis
Compounds 1–7
General method. A mixture of 2-(4-chlorophenoxy)-2-methyl-
propionic acid (0.50 g, 2.35 mmol) and the corresponding ami-
nobenzothiazole (2.53 mmol) was dissolved in dichloromethane
(5 mL) at 0.5 ꢁC. A catalytic amount of dimethylaminopyridine
was added. After that, a solution of dicyclohexylcarbodiimide
(3.52 mmol) in dichloromethane (1 mL) was added to the reac-
tion mixture. The ice bath was removed, and the mixture was
stirred at room temperature between 2 and 24 h for each case.
After the reaction was complete, the mixture was filtered off
through celite, the mother liquors were removed in vacuo, and the
solid residue was dissolved in acetone and filtered again. Acetone
was removed in vacuo to give a solid color (white, yellow or
orange, for each case). The crystals were obtained from meth-
anol, ethanol or acetone for each case.
Fig. 9 Packing of compound 7, showing N–H/N, C–H/Cl, C–H/O
and S/p interactions. Methyl groups and H atoms not involved in the
hydrogen-bonding interactions were omitted for clarity.
These synthons are connected through N–H/Cl and p/p
interactions, thus generating supramolecular chains which are
further interconnected through H/H van der Waals contacts
(distance H/H ¼ 2.2 A)21 to give an overall 2D network (Fig. 8
ꢁ
2
and Table 2). The motifs II and III with graph sets R2 (14) and
4
R4 (44) can be distinguished. The distance between centroids of the
2-(4-Chlorophenoxy)-2-methyl-N-(1,3-benzothiazol-2-yl)pro-
panamide 1. Crystals suitable for X-ray crystallography were
grown from a solution of 1 in methanol (yield 47%). Mp: 135 ꢁC.
Elemental analysis (found: C, 58.85; H, 4.52; N, 7.46; calc. for
C17H15ClN2O2S: C, 58.87; H, 4.36; N, 8.08%). IR (KBr): ~nmax
cmꢀ1 3445 (N–H), 1617 (C]O), 1597 (N]C). dH (400 MHz;
CDCl3; Me4Si): 1.58 (6H, s, C(CH3)2), 6.85 (2Ho, d, 3J ¼ 8.8 Hz,
C6H4ClO), 7.23 (2Hm, d, 3J ¼ 8.8 Hz, C6H4ClO), 7.31 (1H6, dd,
3J ¼ 8.0, 3J ¼ 7.2 Hz, C6H4NS), 7.43 (1H7, dd, 3J ¼ 8.0, 3J ¼ 7.2
Hz, C6H4NS), 7.77 (1H5, d, 3J ¼ 8.0 Hz, C6H4NS), 7.82 (1H8, d,
3J ¼ 8.0, C6H4NS), 10.13 (1H, s, N–H). dC (100 MHz, CDCl3,
Me4Si): 24.9 (C(CH3)2), 82.0 (C(CH3)2), 123.5, 129.7, 129.8,
152.0 (C6H4ClO), 121.4, 121.6, 124.4, 126.5, 132.4, 148.7
(C6H4NS), 157.4 (C]N), 173.3 (C]O). MS (FAB+): m/z (%) 347
([C17H16ClN2O2S]+, 70).
0
ꢁ
chlorophenoxy rings (Cg/Cg ) is 3.77 A. The largest motif (III) is
characterized by transannular Cl1/Cl10, O4/O40 and N2/N20
ꢁ
distances of 12.655(2), 9.786(3) and 17.693(4) A, respectively.
The crystal structure of compound 7 shows neighboring
molecules linked by N–H/N and C–H/Cl hydrogen bonds,
forming dimers. These dimers are interconnected through C–H/
O and S/p interactions, thus generating supramolecular zig-zag
ribbons running along the c axis (Fig. 9 and Table 2). The Cg1/
S1 (Cg1 is the centroid of the aryl ring in the benzothiazole
18,19
ꢁ
moiety) distance is 3.72 A.
Conclusions
The present paper demonstrated that the molecular self-assembly
in the seven crystal structures of the benzothiazole derivatives is
modulated by the cooperative nature of hypervalent and
hydrogen bonding interactions. It is interesting that the full range
of intermolecular interactions found are somehow induced by the
hypervalent intramolecular C]O/S contact. In particular, due
to their cooperative nature, the hydrogen bonds Y–H/X (Y ¼
O, N, C; X ¼ O, N, Cl, p) and van der Waals contacts (Cl/p,
S/p, H/H) induce different 2D or 3D patterns. The bifurcated
hypervalent contacts found in compound 6 are partly favoured
by the NO2 group in the benzothiazole moiety. The variability of
the supramolecular synthons found for this family of compounds
suggests that even subtle structural modifications might lead to
significant modifications in bi- or tridimensional molecular
arrangements.
2-(4-Chlorophenoxy)-2-methyl-N-(6-methyl-1,3-benzothiazol-
2-yl)propanamide 2. Crystals suitable for X-ray crystallography
were grown from a solution of 2 in methanol (yield 25%). Mp:
127 ꢁC. Elemental analysis (found: C, 58.85; H, 4.52; N, 7.46;
calc. for C18H17ClN2O2S$0.5CH3OH: C, 59.04; H, 4.95; N,
7.44%). IR (KBr): ~nmax cmꢀ1 3395 (N–H), 1677 (C]O), 1604
(N]C). dH (400 MHz; CDCl3; Me4Si): 1.57 (6H, s, C(CH3)2),
3
2.45 (3H, s, CH3), 6.84 (2Ho, d, J ¼ 8.8 Hz, C6H4ClO), 7.23
3
(2Hm, d, J ¼ 8.8 Hz, C6H4ClO), 7.61 (1H5, s, C6H3NS), 7.62
(1H7, d, 3J ¼ 8.4 Hz, C6H3NS), 7.64 (1H8, d, 3J ¼ 8.4 Hz,
C6H3NS), 10.12 (1H, s, N–H). dC (100 MHz, CDCl3, Me4Si):
21.7 (CH3), 24.9 (C(CH3)2), 81.9 (C(CH3)2), 123.5, 129.8, 129.8,
152.0 (C6H4ClO), 121.0, 121.4, 128.0, 132.6, 134.4, 146.6
(C6H3NS), 156.6 (C]N), 173.2 (C]O). MS (FAB+): m/z (%) 361
([C18H18ClN2O2S]+, 100).
3
Experimental
3.1 General details
2-(4-Chlorophenoxy)-2-methyl-N-(6-methoxy-1,3-benzothia-
zol-2-yl)propanamide 3. Crystals suitable for X-ray crystallog-
raphy were grown from a solution of 3 in methanol (yield 50%).
Instrumental: NMR studies were carried out with a Varian Inova
400 instrument. Chemical shifts (dH, dC) and J values are given in
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Mp: 94 ꢁC. Elemental analysis (found: C, 57.27; H, 4.22; N, 7.59;
calc. for C18H17ClN2O3S: C, 57.37; H, 4.55; N, 7.43%). IR (KBr):
~nmax cmꢀ1 3365 (N–H), 1693 (C]O), 1603 (N]C). dH (400 MHz;
CDCl3; Me4Si): 1.57 (6H, s, C(CH3)2), 3.85 (3H, s, CH3O), 6.83
2-(4-Chlorophenoxy)-N-(6-methanesulfonyl-1,3-benzothiazol-
2-yl)-2-methylpropanamide 7. Crystals suitable for X-ray crys-
tallography were grown from a solution of 7 in ethanol (yield
43%). Mp: 220 ꢁC. Elemental analysis (found: C, 51.03; H, 4.31;
N, 6.85; calc. for C18H17ClN2O4S2: C, 50.88; H, 4.03; N, 6.59%).
IR (KBr): ~nmax cmꢀ1 3297 (N–H), 1690 (C]O), 1588 (N]C). dH
(400 MHz, CDCl3, Me4Si): 1.68 (6H, s, C(CH3)2), 3.18 (3H, s,
CH3–S), 6.96 (2Ho, d, 3J ¼ 8.6 Hz, C6H4ClO), 7.33 (2Hm, d, 3J ¼
3
3
(2Ho, d, J ¼ 8.8 Hz, C6H4ClO), 7.22 (2Hm, d, J ¼ 8.8 Hz,
3
4
C6H4ClO), 7.01 (1H7, dd, J ¼ 8.8, J ¼ 2.4 Hz, C6H3NS), 7.28
(1H5, d, 4J ¼ 2.4 Hz, C6H4NS), 7.64 (1H8, d, 3J ¼ 8.8 Hz,
C6H3NS), 10.08 (1H, s, N–H). dC (100 MHz, CDCl3, Me4Si):
24.9 (C(CH3)2), 56.0 (OCH3), 81.9 (C(CH3)2), 123.5, 129.7,
129.7, 152.0 (C6H4ClO), 104.3, 115.6, 122.0, 133.7, 142.9, 155.4
(C6H3NS), 157.2 (C]N), 173.1 (C]O). MS (FAB+): m/z (%) 377
([C18H18ClN2O3S]+, 70).
3
8.6 Hz, C6H4ClO), 7.95 (1H7, d, J ¼ 8.8 Hz, C6H3NS), 8.04
3
(1H8, d, J ¼ 8.8 Hz, C6H3NS), 8.53 (1H5, s, C6H3NS), 10.34
(1H, s, N–H). dC (100 MHz, CDCl3, Me4Si): 24.2 (C(CH3)2), 80.7
(C(CH3)2), 123.4, 129.7, 130.0, 152.3 (C6H4ClO), 121.9, 121.9,
125.3, 132.9, 136.0, 151.7 (C6H3NS), 161.1 (C2), 173.08 (C]O).
MS (FAB+): m/z (%) 425 ([C18H18ClN2O4S2]+, 100).
2-(4-Chlorophenoxy)-2-methyl-N-(6-ethoxy-1,3-benzothiazol-
2-yl)propanamide 4. Crystals suitable for X-ray crystallography
were grown from a solution of 4 in methanol (yield 51%). Mp:
152 ꢁC. Elemental analysis (found: C, 56.11; H, 4.82; N, 6.72;
calc. for C19H19ClN2O3S$CH3OH: C, 56.80; H, 5.48; N, 6.62%).
IR (KBr): ~nmax cmꢀ1 3156 (N–H), 1693 (C]O), 1597 (N]C). dH
(400 MHz; CDCl3; Me4Si): 1.46 (3H, t, 3J ¼ 6.8 Hz, CH3CH2O),
3.3 X-Ray crystallography
X-Ray diffraction studies were performed on a Bruker-APEX
ꢁ
diffractometer with a CCD area detector (lMoka ¼ 0.71073 A,
monochromator: graphite). Frames were collected at T ¼ 100 K
(compounds 1, 2, 4), T ¼ 173 K (compounds 3 and 5) and T ¼
294 K (compounds 6 and 7) via u/f-rotation at 10 s per frame
(SMART).22a The measured intensities were reduced to F2 and
corrected for absorption with SADABS (SAINT-NT).22b
Corrections were made for Lorentz and polarization effects.
Structure solution, refinement and data output were carried out
with the SHELXTL-NT program package.22c,d Non-hydrogen
atoms were refined anisotropically. C–H hydrogen atoms were
placed in geometrically calculated positions using a riding model.
O–H and N–H hydrogen atoms were localized by difference
Fourier maps and refined fixing the bond lengths to 0.840(1) and
3
4.10 (2H, q, J ¼ 6.8 Hz, CH3–CH2O), 1.60 (6H, s, C(CH3)2),
6.89 (2Ho, d, 3J ¼ 8.8 Hz, C6H4ClO), 7.26 (2Hm, d, 3J ¼ 8.8 Hz,
3
4
C6H4ClO), 7.04 (1H7, dd, J ¼ 9.2, J ¼ 2.4 Hz, C6H3NS), 7.30
(1H5, d, 4J ¼ 2.4 Hz, C6H4NS), 7.66 (1H8, d, 3J ¼ 9.2 Hz,
C6H3NS), 10.0 (1H, s, N–H). dC (100 MHz, CDCl3, Me4Si): 15.0
(CH3CH2O), 64.3 (CH3CH2O), 24.9 (C(CH3)2), 81.9 (C(CH3)2),
123.5, 129.7, 129.8, 152.0 (C6H4ClO), 105.1, 116.0, 122.0, 133.6,
142.8, 155.2 (C6H3NS), 156.5 (C]N), 173.0 (C]O). MS
(FAB+): m/z (%) 391 ([C19H20ClN2O3S]+, 100).
2-(4-Chlorophenoxy)-2-methyl-N-(6-chloro-1,3-benzothiazol-
2-yl)propanamide 5. Crystals suitable for X-ray crystallography
were grown from a solution of 5 in methanol (yield 51%). Mp:
146 ꢁC. Elemental analysis (found: C, 53.0; H, 3.47; N, 7.14; calc.
for C17H14Cl2N2O2S: C, 53.55; H, 3.70; N, 7.35%). IR (KBr):
~nmax cmꢀ1 3339 (N–H), 1683 (C]O), 1604 (N]C). dH (400 MHz;
CDCl3; Me4Si): 1.60 (6H, s, C(CH3)2), 6.89 (2Ho, d, 3J ¼ 8.8 Hz,
C6H4ClO), 7.27 (2Hm, d, 3J ¼ 8.8 Hz, C6H4ClO), 7.41 (1H7, dd,
ꢁ
0.860(1) A, respectively; the corresponding isotropic temperature
factors have been fixed to a value 1.5 times that of the corre-
sponding oxygen/nitrogen atoms. Hydrogen-bonding interac-
tions in the crystal lattice were calculated with the PLATON
program package.22e In the final electron density map of
compound 2 there are peaks with maximum residual electron
densities of Dr ¼ 0.42 (Q1) and 0.41 (Q2), which are located in
the proximity of the chlorine and sulfur atoms. The distances
4
3
3J ¼ 8.6, J ¼ 2.0 Hz, C6H3NS), 7.67 (1H8, d, J ¼ 8.6 Hz,
C6H4NS), 7.82 (1H5, d, 4J ¼ 2.0 Hz, C6H3NS), 10.1 (1H, s, N–H).
dC (100 MHz, CDCl3, Me4Si): 24.9 (C(CH3)2), 81.9 (C(CH3)2),
123.5, 129.7, 129.9, 151.9 (C6H4ClO), 121.2, 122.1, 127.2, 129.9,
133.7, 147.3 (C6H3NS), 157.7 (C]N), 173.4 (C]O). MS
(FAB+): m/z (%) 381 ([C17H15Cl2N2O2S]+, 70).
ꢁ
between Q1/S1 and Q2/Cl1 were 0.93 and 0.96 A, respec-
tively; the residual void was verified with PLATON/SQUEEZE
3
3
ꢁ
ꢁ
(volume 147.5 A per unit cell volume 3530.7 A [4.2%]).
Figures were drawn with DIAMOND using spheres of arbi-
trary radius.22f
2-(4-Chlorophenoxy)-2-methyl-N-(6-nitro-1,3-benzothiazol-2-
yl)propanamide 6. Crystals suitable for X-ray crystallography
were grown from a solution of 6 in methanol/water (yield 43%).
Mp: 188–189 ꢁC. Elemental analysis (found: C, 50.20; H, 3.58; N,
10.01; calc. for C17H14ClN3O4S$H2O: C, 49.82; H, 3.93; N,
10.25%). IR (KBr): ~nmax cmꢀ1 3348 (N–H), 1697 (C]O), 1588
(N]C). dH (400 MHz, CDCl3, Me4Si): 1.62 (6H, s, C(CH3)2),
6.93 (2Ho, d, 3J ¼ 8.6 Hz, C6H4ClO), 7.30 (2Hm, d, 3J ¼ 8.6 Hz,
C6H4ClO), 7.85 (1H8, d, 3J ¼ 8.8 Hz, C6H3NS), 8.34 (1H7, dd, 3J
¼ 8.8, J ¼ 2.4 Hz, NO2Ph), 8.80 (1H5, d, 4J ¼ 2.4 Hz, C6H3NS),
10.23 (1H, s, N–H). dC (100 MHz, CDCl3, Me4Si): 24.9 (C
(CH3)2), 82.1 (C(CH3)2), 123.7, 129.9, 130.3, 151.7 (C6H4ClO),
118.4, 121.4, 122.3, 132.8, 144.4, 153.2 (C6H3NS), 161.8 (C2),
173.8 (C]O). MS (FAB+): m/z (%) 392 ([C17H15ClN3O4S]+, 20).
Acknowledgements
The authors thank CONACyT for financial support through
project no. SEP-2004-C01-47347 and CONACyT grant 100608
(GNV).
References
1 (a) J. de Mendoza, Chem.–Eur. J., 1998, 4, 1373–1377; (b) M. Fujita,
Chem. Soc. Rev., 1998, 27, 417–425; (c) C. J. Jones, Chem. Soc. Rev.,
1998, 27, 289–299; (d) L. R. MacGillivray and J. L. Atwood, Angew.
Chem., Int. Ed., 1999, 38, 1018–1033; (e) D. L. Caulder and
K. N. Raymond, J. Chem. Soc., Dalton Trans., 1999, 1185–1200; (f)
A. Jasat and J. C. Sherman, Chem. Rev., 1999, 99, 931–968; (g)
J. W. Steed and J. L. Atwood, Supramolecular Chemistry, John
Wiley & Sons, Ltd., UK, 2000; (h) F. Hof, S. L. Craig, C. Nuckolls
1262 | CrystEngComm, 2012, 14, 1256–1263
This journal is ª The Royal Society of Chemistry 2012

View Article Online
11 J. M. Thorp and W. S. Waring, Nature, 1962, 194, 948–949.
12 G. Jayanthi, S. Muthusamy, R. Paramasivam, V. T. Ramakrishnan,
N. K. Ramasamy and P. Ramamurthy, J. Org. Chem., 1997, 62,
5766–5770.
13 I. Caleta, D. Cincic, G. Karminsky-Zamola and B. Kaitner, J. Chem.
Crystallogr., 2008, 38, 775–780.
14 J. Bernstein, R. E. Davis, L. Shimoni and N.-L. Chang, Angew.
Chem., Int. Ed. Engl., 1995, 34, 1555–1573.
and J. Rebek, Jr, Angew. Chem., Int. Ed., 2002, 41, 1488–1508; (i)
C. Schmuck, Angew. Chem., Int. Ed., 2007, 46, 5830–5833; (j)
ꢀ
C. Pariya, C. R. Sparrow, C.-K. Back, G. Sandı, F. R. Fronczek
and A. W. Maverick, Angew. Chem., Int. Ed., 2007, 46, 6305–6308;
(k) Q.-R. Fang, G.-S. Zhu, Z. Jin, Y.-Y. Ji, J.-W. Ye, M. Xue,
H. Yang, Y. Wang and S.-L. Qiu, Angew. Chem., Int. Ed., 2007, 46,
6638–6642; (l) K. Uemura, Y. Yamasaki, Y. Komagawa,
K. Tanaka and H. Kita, Angew. Chem., Int. Ed., 2007, 46, 6662–
6665; (m) J. A. R. P. Sarma and G. R. Desiraju, Acc. Chem. Res.,
1986, 19, 222–228.
15 (a) R. E. Rosenfield, R. Parthasarathy and J. D. Dunitz, J. Am. Chem.
Soc., 1977, 99, 4860–4862; (b) C. Cohen-Addad, M. S. Lehmann,
ꢀ
ꢀ
ꢀ
ꢀ
2 (a) J.-M. Lehn, Angew. Chem., Int. Ed. Engl., 1990, 29, 1304–1319; (b)
G. A. Jeffrey and W. Saenger, Hydrogen Bonding in Biological
Structures, Springer, Berlin, 1991; (c) J.-M. Lehn, Supramolecular
Chemistry: Concepts and Perspectives, VCH, Weinheim, New York,
1995; (d) J.-M. Lehn, J. L. Atwood, J. E. D. Davies,
P. Becker, L. Parkanyi and A. Kalman, J. Chem. Soc., Perkin
Trans. 2, 1984, 191–196; (c) N. Pandya, A. J. Basile, A. K. Gupta,
P. Hand, C. L. MacLaurin, T. Mohammad, E. S. Ratemi,
M. S. Gibson and M. F. Richardson, Can. J. Chem., 1993, 71, 561–
ꢀ
ꢀ
571; (d) J. G. Angyan, R. A. Poirier, A. Kucsman and
I. G. Csizmadia, J. Am. Chem. Soc., 1987, 109, 2237–2245; (e)
€
D. D. MacNicol and F. Vogtle, Comprehensive Supramolecular
~
ꢀ
A. Esparza-Ruiz, A. Pena-Hueso, J. Hernandez-Dıaz, A. Flores-
Parra and R. Contreras, Cryst. Growth Des., 2007, 7, 2031–2040; (f)
ꢀ
Chemistry, Pergamon, Oxford, 1996; (e) M. M. Conn and J. Rebek,
Jr, Chem. Rev., 1997, 97, 1647–1668; (f) G. Desiraju and T. Steiner,
The Weak Hydrogen Bond in Structural Chemistry and Biology,
ꢀ
F. Tellez, A. Cruz, H. Lopez-Sandoval, I. Ramos-Garcıa,
M. Gayosso, R. N. Castillo Sierra, B. Paz-Michel, H. Noth,
ꢀ
€
€
Oxford University Press, New York, 1999; (g) K. Muller-Dethlefts
and P. Hobza, Chem. Rev., 2000, 100, 143–167; (h) S. Leininger,
B. Olenyuk and P. J. Stang, Chem. Rev., 2000, 100, 853–908; (i)
M. J. Calhorda, Chem. Commun., 2000, 801–809; (j) G. R. Desiraju,
Acc. Chem. Res., 2002, 35, 565–573; (k) T. Steiner, Angew. Chem.,
Int. Ed., 2002, 41, 48–76; (l) M. A. Buntine, F. J. Kosovel and
E. R. T. Tiekink, CrystEngComm, 2003, 5, 331–336.
A. Flores Parra and R. Contreras, Eur. J. Org. Chem., 2004, 4203–
ꢀ
ꢀ
4214; (g) Z. Garcıa-Hernandez, A. Flores Parra, J. M. Grevy,
A. Ramos-Organillo and R. Contreras, Polyhedron, 2006, 25, 1662–
1672; (h) K. Lekin, S. M. Winter, L. E. Downie, X. Bao, J. S. Tse,
S. Desgreniers, R. A. Secco, P. A. Dube and R. T. Oakley, J. Am.
Chem. Soc., 2010, 132, 16212–16224.
3 (a) J. Starbuck, N. C. Norman and A. G. Orpen, New J. Chem., 1999,
23, 969–972; (b) V. I. Minkin and R. M. Minyaev, Chem. Rev., 2001,
101, 1247–1265; (c) F. Iwasaki, N. Toyoda and N. Yamazaki, Acta
Crystallogr., Sect. C: Cryst. Struct. Commun., 1989, 45, 1914–1917;
16 F. H. Allen, O. Kennard, D. G. Watson, L. Brammer, A. G. Orpen
and R. Taylor, J. Chem. Soc., Perkin Trans. 2, 1987, S1.
17 (a) R. Taylor, O. Kennard and W. Versichel, J. Am. Chem. Soc., 1983,
105, 5761–5766; (b) R. Taylor, O. Kennard and W. Versichel, J. Am.
Chem. Soc., 1984, 106, 244–248.
18 (a) L. R. Hanton, C. A. Hunter and D. H. Purvis, J. Chem. Soc.,
Chem. Commun., 1992, 1134–1136; (b) H. Adams, F. J. Carver,
C. A. Hunter, J. C. Morales and E. M. Seward, Angew. Chem., Int.
Ed. Engl., 1996, 35, 1542–1544; (c) P. Munshi and T. N. G. Row,
CrystEngComm, 2005, 7, 608–611; (d) J.-A. van den Berg and
K. R. Seddon, Cryst. Growth Des., 2003, 3, 643–661; (e)
ꢃ
ꢀ
ꢀ
(d) J. G. Angyan, R. A. Poirier, A. Kucsman and I. G. Csizmadia,
J. Am. Chem. Soc., 1987, 109, 2237–2245; (e) T. Atsumi, T. Abe,
K. Akiba and H. Nakai, Bull. Chem. Soc. Jpn., 2010, 83, 892–899;
ꢀ
ꢀ
(f) J. I. Arenas-Garcıa, D. Herrera-Ruiz, K. Mondragon-Vasquez,
H. Morales-Rojas and H. Hopfl, Cryst. Growth Des., 2010, 10,
ꢀ
€
3732–3742.
4 (a) L. J. W. Shimon, M. Vaida, L. Addadi, M. Lahav and
L. Leiserowitz, J. Am. Chem. Soc., 1990, 112, 6215–6220; (b)
E. M. D. Keegstra, A. L. Spek, J. W. Zwikker and
L. W. Jenneskens, J. Chem. Soc., Chem. Commun., 1994, 1633–
1634; (c) G. R. Desiraju, Angew. Chem., Int. Ed. Engl., 1995, 34,
2311–2327.
€€
J. G. Planas, C. Masalles, R. Sillanpaa, R. Kivekas, F. Teixidor
and C. Vinas, CrystEngComm, 2006, 8, 75–83; (f) A. K. Tewari and
€
~
R. Dubey, ARKIVOC (Gainesville, FL, U. S.), 2009, 283–291.
19 (a) P. K. Thallapally and A. Nangia, CrystEngComm, 2001, 27, 1–6;
(b) M. Freytag and P. G. Jones, Chem. Commun., 2000, 277–278;
€
ꢀ
ꢀ
5 (a) Z. S. Derewenda, U. Derewenda and P. M. Kobos, J. Mol. Biol.,
1994, 241, 83–93; (b) Z. S. Derewenda, L. Lee and U. Derewenda, J.
Mol. Biol., 1995, 252, 248–262.
(c) C. B. Aakeroy, T. A. Evans, K. R. Seddon and I. Palinko, New
J. Chem., 1999, 23, 145–152; (d) R. G. Gonnade, M. S. Shashidhar
and M. M. Bhadbhade, J. Indian Inst. Sci., 2007, 87, 149–164; (e)
€
I. Csoregh, E. Weber, T. Hens and M. Czugler, J. Chem. Soc.,
6 (a) T. Steiner and W. Saenger, J. Chem. Soc., Chem. Commun., 1995,
2087–2088; (b) D. Braga, F. Grepioni, J. J. Byrne and A. Wolf, J.
Chem. Soc., Chem. Commun., 1995, 1023–1024.
ꢀ
Perkin Trans. 2, 1996, 2733–2739; (f) G. Aullon, D. Bellamy,
L. Brammer, E. A. Bruton and A. G. Orpen, Chem. Commun.,
1998, 653–654.
€
7 G. Muller, M. Lutz and S. Harder, Acta Crystallogr., Sect. B: Struct.
Sci., 1996, 52, 1014–1022.
20 (a) G. R. Desiraju, Angew. Chem., Int. Ed. Engl., 1995, 34, 2311–2327;
(b) I. Caleta, D. Cincic and G. Karminski-Zamola, J. Chem.
Crystallogr., 2008, 38, 775–780.
21 (a) M. A. Spackman and J. J. McKinnon, CrystEngComm, 2002, 4,
378–392; (b) R. S. Rowland and R. Taylor, J. Phys. Chem., 1996,
100, 7384–7391; (c) J. D. Dunitz and A. Gavezzotti, Acc. Chem.
Res., 1999, 32, 677–684; (d) T. Steiner and G. R. Desiraju, Chem.
Commun., 1998, 891–892.
8 (a) A. K. Abdul-Sada, A. M. Greenway, P. B. Hitchcock,
T. J. Mohammed, K. R. Seddon and J. A. Zora, J. Chem. Soc.,
Chem. Commun., 1986, 1753–1754; (b) A. G. Avent, P. A. Chaloner,
M. P. Day, K. R. Seddon and T. Welton, J. Chem. Soc., Dalton
Trans., 1994, 3405–3413.
ꢀ
9 (a) G. Navarrete-Vazquez, P. Paoli, I. Leon-Rivera, R. Villalobos-
Molina, J. L. Medina-Franco, R. Ortiz-Andrade, S. Estrada-Soto,
~
G. Camici, D. Diaz-Coutino, I. Gallardo-Ortiz, K. Martinez-
Mayorga and H. Moreno-Dıaz, Bioorg. Med. Chem., 2009, 17, 3332–
22 (a) Bruker Analytical X-ray Systems, SMART: Bruker Molecular
Analysis Research Tool, Versions 5.057 and 5.618, 1997 and 2000;
(b) Bruker Analytical X-ray Systems, SAINT + NT, Versions 6.01
and 6.04, 1999 and 2001; (c) G. M. Sheldrick, SHELX86, Program
ꢀ
ꢀ
3341; (b) H. Moreno-Dıaz, R. Villalobos-Molina, R. Ortiz-Andrade,
D. Dıaz-Coutino, J. L. Medina-Franco, S. P. Webster, M. Binnie,
ꢀ
~
ꢀ
S. Estrada-Soto, M. Ibarra-Barajas, I. Leon-Rivera and G. Navarrete-
Vazquez, Bioorg. Med. Chem. Lett., 2008, 18, 2871–2877.
€
for Crystal Structure Solution, University of Gottingen, Germany,
ꢀ
1986; (d) Bruker Analytical X-ray Systems, SHELXTL-NT Versions
5.10 and 6.10, 1999 and 2000; (e) A. L. Spek, J. Appl. Crystallogr.,
2003, 36, 7–13; (f) DIAMOND, Visual Crystal Structure
Information System, Version 3.1, CRYSTAL IMPACT, Postfach
1251, D-53002, Bonn, Germany, 2006.
10 (a) J. M. Thorp, Lancet, 1962, 1, 1323–1326; (b) D. B. Miller and
J. D. Spence, Clin. Pharmacokinet., 1998, 34, 155–162; (c)
F. Forcheron, A. Cachefo, S. Thevenon, C. Pinteur and M. Beylot,
Diabetes, 2002, 51, 3486–3491.
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