Supramolecular networks in crystalline inclusion complexes formed from a new host: 2,2-bis(4-hydroxy-3-phenylphenyl)-1 h -indene-1,3(2 h)-dione

Article abstract of DOI:10.1021/cg200554f

A scissors-shaped compound, 2,2-bis(4-hydroxy-3-phenylphenyl)-1H-indene-1, 3(2H)-dione (1), has been prepared as a new host species for crystalline host-guest complexes. Compound 1 afforded complexes of 1:1 host-to-guest ratio with acetone, EtOH, and CH

Full text of DOI:10.1021/cg200554f

ARTICLE
pubs.acs.org/crystal
Supramolecular Networks in Crystalline Inclusion Complexes
Formed from a New Host: 2,2-Bis(4-hydroxy-3-phenylphenyl)-1H-
indene-1,3(2H)-dione
Kenta Kasugai,† Suzumi Hashimoto,† Kazunori Imai,† Aya Sakon,‡ Kotaro Fujii,‡ Hidehiro Uekusa,‡
Naoto Hayashi,§ and Keiji Kobayashi*,†
†Department of Chemistry, Graduate School of Material Science, Josai University, Sakado, Saitama 350-0295, Japan
‡Department of Chemistry and Material Science, Tokyo Institute of Technology, Ookayama, Meguro-ku, Tokyo 152-8551, Japan
§Graduate School of Science and Engineering, University of Toyama, Gofuku, Toyama, 930-8555, Japan
S Supporting Information
b
ABSTRACT: A scissors-shaped compound, 2,2-bis(4-hydroxy-
3-phenylphenyl)-1H-indene-1,3(2H)-dione (1), has been pre-
pared as a new host species for crystalline hostÀguest com-
plexes. Compound 1 afforded complexes of 1:1 host-to-guest
ratio with acetone, EtOH, and CH2Cl2, and a 2:3 complex with
benzene. The crystal structures of these complexes were
elucidated. In all four crystals, a side-by-side dimer linked by
head-to-tail >CdO
HOÀ hydrogen bonds is formed and
3 3 3
functions as the building unit of supramolecular networks. Except for (1)2(benzene)3, the complexes featured intermolecular
carbonylÀcarbonyl interactions resulting in all-planar antiparallel alignment with markedly short C
O distances (< 3.15 Å).
3 3 3
In (1)(EtOH), the four-centered interaction including two hydroxyl and two carbonyl groups was observed and designated as
a quasi-bifurcated hydrogen bonding motif. Such a four-centered interaction has been observed to occur widely in crystal
structures as proved by database searches from the Cambridge Structural Database (CSD). In all the crystals, the host
molecules formed a channel-type void occupied by guest molecules. The crystal structure of the desolvated crystals of 1 has
been elucidated for its polycrystalline solids by ab initio structure determination from powder X-ray diffraction data followed
by the Rietveld refinement.
’ INTRODUCTION
functional groups, hydroxyl and carbonyl groups, that can
interact not only between the host molecules complementarily
but also between the host and guest components. If a possible
conformation of Cs symmetry is retained, host 1 is expected to
form a three-dimensional hydrogen bonding network by using
The design of crystalline inclusion complexes is a challenging
subject because there are no general methods for the prediction
of organic crystal structures by computational methods despite
recent developments.1 Strategies for hostÀguest assembly rely
on programmed recognition between topologically and chemi-
cally complementary functional groups through noncovalent
interactions, referred to as supramolecular synthons.2 Hydrogen
bonds are commonly employed as a reliable adhesive to produce
specific and robust patterns.3 The presence of rigid and bulky
moieties within the host structure has also been identified as a
positive attribute to provide suitable cavities to accommodate a
guest molecule.4 From the geometric point of view, scissors-
shaped,5 roof-shaped,6 and wheel-and-axle-shaped hosts7 have
been shown to form crystalline supramolecular assemblies with
suitable guests.
all functional groups as cross-linked >CdO
HOÀ hydro-
3 3 3
gen bonding sites. Although this intention was not realized,
host compound 1 has been found to form inclusion complexes
with solvent molecules as guest species, and their crystal
structures showed peculiar supramolecular networks consist-
ing of inter-homomolecular and inter-heteromolecular hydro-
gen bonds, interhostÀmolecular interactions of the >C(δ+)d
O(δÀ) dipole, and four-centered interactions involving two
hydroxyl and two carbonyl groups. Here, we present char-
acteristic crystal structures of the inclusion crystals of host 1,
principally focusing on a hydrogen bonding motif, along with
that of guest-free 1, which was obtained as a polycrystalline
solid by thermal guest release. For the latter, the crystal
We have now tested a host design involving a scissors-shaped
basic skeleton, 2,2-bis(4-hydroxy-3-phenylphenyl)-1H-indene-
1,3(2H)-dione (1).8 Almost all scissors-shaped host compounds
reported to date incorporate one type of functional group,
Received: May 15, 2011
principally, the hydroxyl function, to engage in OH (H)O
hydrogen bonding. In contrast, compound 1 consists of two
Revised:
Published: July 06, 2011
July 1, 2011
3 3 3
r
2011 American Chemical Society
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Table 1. Crystallographic Parameters of Inclusion Complexes Derived from Host 1
(1)2(benzene)3
(1)(acetone)
(1)(EtOH)
(1)(CH2Cl2)
T °C
formula
À50
23
À50
À50
C84H62O8
monoclinic
P21/a(#14)
15.775(5)
9.796(2)
20.695(5)
90
C36H28O5
triclinic
P1(#2)
C35H28O5
triclinic
P1(#2)
9.343(4)
11.137(6)
14.234(6)
112.231(18)
96.642(19)
98.197(17)
1338.8(10)
2
C34H24O4Cl2
monoclinic
P21(#4)
9.3881(19)
26.515(6)
11.103(3)
90
crystal system
space group
a/Å
9.3492(4)
11.2462(5)
14.0186(6)
74.5463(12)
79.4118(14)
83.2828(15)
1392.87(11)
2
b/Å
c/Å
R/ο
β/ο
γ/ο
V/Å3
94.896(11)
90
97.768(10)
90
3186.3(14)
2
2738.5(10)
4
Z
dcalc/g cmÀ3
1.250
1.289
1.316
1.376
reflections collected
independent reflections
no. of reflections used
R1
30516
13762
13289
44508
7276
6298
6090
12534
5497
6298
4372
7424
0.0431
0.0107
0.0422
0.0658
0.0604
wR2
0.1300
0.2158
0.0985
Figure 1. Molecular arrangement of the host molecules in (1)2-
(benzene)3. For clarity, all hydrogen atoms are omitted. The oxygen
atoms related to hydrogen bonding are linked by blue dashed lines. The
red benzene molecules are located on the crystallographic inversion
center.
Figure 2. Crystal structure of (1)2(benzene)3 as viewed down the b-axis
showing the channel embedded with guest molecules.
structure was determined from synchrotron powder X-ray
diffraction data.
poor crystallinity. The guest molecules were not released to form
guest-free crystals after standing for three weeks at room
temperature except for (1)(CH2Cl2), which collapsed within a
few days. The crystal structures of (1)2(benzene)3, (1)(acetone),
(1)(EtOH), and (1)(CH2Cl2) were elucidated (Table 1).
The crystal structure of (1)2(benzene)3 is shown in Figure 1.
The host molecules are linked by complementary intermolecular
>CdO HOÀ hydrogen bonds to form an infinite chain along
3 3 3
the a-axis. The two >CdO HO hydrogen bonds connecting
3 3 3
the molecules show markedly different O(H) O distances:
3 3 3
one is 2.730 Å, while the other is 2.989 Å. These observations
imply that a neighboring pair of host molecules, and hence the
dimeric motif in (1)2(benzene)3, is not in a centrosymmetric
arrangement. The guest molecules are located in channel-type
voids formed by the host chain parallel to the b-axis and show no
specific modes of hostÀguest binding (Figure 2). Thus, the
enclosure of benzene in (1)2(benzene)3 occurs as a clathrate
formation in terms of the original meaning (true clathrates).9
The structural unit observed in (1)2(benzene)3, a cyclic dimer
’ RESULTS AND DISCUSSION
Crystal Structures. Among the various solvents used for
recrystallization (clathration) experiments on 1, acetone, di-
chloromethane, benzene, and ethanol gave single crystals suited
for X-ray analysis. Their host-to-guest stoichiometry was 1:1,
except for benzene, which afforded a rather uncommon 2:3
stoichiometry. Other solvents such as acetonitrile (1:1), chloro-
form (1:1), and pyridine (2:1) afforded inclusion crystals, but
their crystal structures were not characterized because of their
linked by two CdO HO hydrogen bonds, is commonly
3 3 3
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Scheme 1. Diagrammatic Representation of a Supramolecular Network Based on the Dimeric Unit, Showing Hydrogen Bonding
with Guest Molecules, CarbonylÀCarbonyl Interactions between Dimeric Units, and Four-Centered Quasi-Bifurcated Hydrogen
Bondinga
a The hydrogen bonding with guest molecules is represented as G HO. (a) (1)2(benzene)3, (b) (1)(acetone), (c) (1)(EtOH), and (d)
3 3 3
(1)(CH2Cl2).
accepted for carbonylÀcarbonyl interactions.10,11 This type of
carbonylÀcarbonyl interaction is observed between cyclic di-
mers in all crystals except for (1)2(benzene)3 (Scheme 1,
Table 2). The host molecules provide a channel running along
the a-axis, in which guest molecules are embedded by hydrogen
bonding (Figure 4a).
The host lattice in the crystal structure of (1)(EtOH) is similar
to that of (1)(acetone). The centrosymmetric dimeric unit, in
which the OH OdC< hydrogen bonds have an O(H)
O
3 3 3
3 3 3
distance of 2.776 Å, is linked further by carbonylÀcarbonyl
interactions to make a linear chain of host molecules along the
a-axis: the guest molecule is connected to this chain by hydrogen
bonding (O(H) (H)OEt: 2.753 Å). Thus, the guest mol-
3 3 3
ecules are embedded in the channels running along the a-axis
(Figure 4b). This packing motif of host molecules is similar to
that of (1)(acetone). In (1)(EtOH), however, the OH and CdO
groups involved in the formation of the dimeric unit participate
further in hydrogen bonding between dimers of the neighboring
chain. Thus, a centrosymmetric cyclic assembly of four host molec-
ules is formed by an alternative arrangement of the hydroxyl and
carbonyl groups (Figure 5, Scheme 1c). We discuss this hydro-
gen bonding motif, designated as a four-centered quasi-bifur-
cated hydrogen bonding motif, in the following section.
The crystallographic study of (1)(CH2Cl2) has recently been
reported by Adams et al.8 Our structural analysis of this solvate
crystal is consistent with their results. Figure 6 shows the crystal
structure of (1)(CH2Cl2), which belongs to the chiral space
group P212121. Chirality in the crystallization of an achiral
compound has arisen from helical arrangement of the chiral
dimeric units formed by conformationally fixed molecules of 1.
The guest molecules are included in channels made by the host
lattice (Figure 4c). There are two crystallographically indepen-
dent CH2Cl2 molecules in a unit cell. One of these is free of
specific noncovalent interactions, while the other seems to
interact with the host molecule through close contact of the
Figure 3. Crystal structure of (1)(acetone) showing the carbonylÀ
carbonyl interaction between the dimers. The oxygen and carbon atoms
related to the (Cd)O C(dO) interactions are linked by blue dashed
3 3 3
lines. For clarity, all hydrogen atoms are omitted.
observed in all the crystals investigated in this work (Scheme 1).
In the dimeric unit, two hydroxyl and two carbonyl groups are
free for hydrogen bonding to other dimer or solvent molecules.
These groups control the supramolecular network in the crystal
structure.
The crystal structure of (1)(acetone) is shown in Figure 3.
Two host molecules associate to form a centrosymmetric cyclic
dimer (O(H) OdC: 2.779 Å). Two guest molecules join this
3 3 3
host unit as hydrogen bond acceptors resulting in a 1:1
hostÀguest stoichiometry (O(H) OdC(CH3)2: 2.827 Å).
3 3 3
The noncovalent carbonylÀcarbonyl interaction due to the
>C(δ+)dO(δÀ) dipole is observed between the dimeric units,
which makes an infinite linear chain of host molecules along the
b-axis (Scheme 1b). The carbonyl groups of the neighboring
molecules are in close contact with the antiparallel arrangement
with zero torsional angle, indicating an all-planar antiparallel
arrangement of the two CdO groups. The C O distance is
3.147 Å, which is markedly shorter than the 3.6 Å distance
chlorine atom to the aromatic ring (Cl C; 3.444 Å) within the
sum of their van der Waals radii (Cl + C: 3.45 Å). The geometry
3 3 3
3 3 3
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Table 2. Structural Parameters of CarbonylÀCarbonyl Interactions in Inclusion Crystals Based on 1
Figure 4. Channel structure of the host lattice in (a) (1)(acetone), (b) (1)(EtOH), and (c) (1)(CH2Cl2) as viewed down the a-axis, showing the
channel embedded with guest molecules.
(Table 2). Despite such deformations, the host molecules retain
the arrangement of a linear chain linked by OH
OdC
3 3 3
hydrogen bonds and CdO
CdO interactions, as observed
3 3 3
in (1)(EtOH) and (1)(acetone). The hostÀguest hydrogen
bond found in (1)(acetone) is replaced by a hostÀhost hydrogen
bond. Thus, the OH OH hydrogen bonds bridge the linear
3 3 3
chain of the host dimers (O(H)---OH: 2.921 Å).
Four-Centered Interactions through Quasi-Bifurcated
Hydrogen Bonding. In the crystal structure of (1)(EtOH), the
two >CdO HOÀ hydrogen bonding motifs are aligned in a
3 3 3
parallel and head-to-tail manner. The hydroxyl group appears to
participate as a H-donor in a bifurcated hydrogen bond to the
two carbonyl oxygen atoms, and at the same time, the carbonyl
oxygen joins a bifurcated hydrogen bond as a H-acceptor for the
two hydroxyl groups (Scheme 3c). However, judging from the
Figure 5. Four-centered interaction between the host dimers in
(1)(EtOH) showing alternative contact of the hydroxyl and carbo-
nyl oxygen atoms. For clarity, all hydrogen atoms are omitted.
The oxygen atoms related to hydrogen bonding are linked by blue
dashed lines.
CdO (H)O distances, the interchain hydrogen bonding is
3 3 3
of the host dimer in (1)(CH2Cl2) is not centrosymmetric; the
appreciably weaker than that in the dimeric unit; the former is
2.776 Å, while the latter is 3.036 Å (Scheme 2a). Therefore,
strictly speaking, the cyclic hydrogen bonding motif observed in
O(H) OH distances are 2.777 and 2.729 Å. Distortion from a
3 3 3
parallelogram is also observed in the carbonylÀcarbonyl interaction
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considering the dipolar interactions between the two >CdO
3 3 3
HÀOÀ hydrogen bonding systems aligned in antiparallel or-
ientation (Scheme 3b). Both the carbonyl and hydroxyl oxygen
atoms involved in the hydrogen bonding should be highly
polarized and therefore become favorable at the same time
for dipoleÀdipole interactions between the >CdO HÀOÀ
3 3 3
systems (Scheme 2b).
The motif of four-centered quasi-bifurcated hydrogen bond-
ing has been overlooked so far despite its highly frequent
occurrence in molecular crystals. Thus, in the Cambridge Struc-
tural Database (ver. 5.32, November 2010 + 1 update; 525,095
entries), we examined the structural fragments in which two
hydrogen bonding systems of >CdO (H)OÀ are closely
3 3 3
aligned to make a four-membered cycle with the four oxygen
atoms. The O O distances, d1, d2, d3, and d4, were defined as
3 3 3
depicted in Scheme 3a and were restrained within a range from
2.5 to 3.2 Å for d1 and d2, and from 2.5 to 6.0 Å for d3 and d4. The
former includes both intramolecular and intermolecular con-
tacts, whereas the latter is restricted only to the intermolecular
one. The search for this data set (data set A) gave 56 715 hits. In
order to search all-planar antiparallel alignment of the two
Figure 6. Crystal structure of (1)(CH2Cl2). The OH O(H) hydro-
gen bonds are shown by blue dashed lines and the oxygen atoms related
3 3 3
to the CdO CdO interaction are linked by red dashed lines.
3 3 3
(Cd)O (H)OÀ fragments (Figure 3b,c), that is, a parallelo-
3 3 3
gram arrangement of the four oxygen atoms, secondary search
Scheme 2. (a) Schematic Representation of Four-Centered
Quasi-Bifurcated Hydrogen Bonding in (1)(EtOH); Hydro-
gen Bonding (Red) and DipoleÀDipole Interaction (Blue)a;
criteria were applied to data set A so that the O O lengths of
3 3 3
opposite sides were equal (d1 = d2 and d3 = d4) and the sum of the
interior angles was 360° (data set B). The search for data set B
gave 19 354 hits.
The scatter plot ofd1 (= d2) vs d3 (= d4) in data set B is shown in
Figure 7a. The distance d1 ranges mostly between 2.6 and 2.9 Å,
whereas d3 is scattered in longer distances over 4 Å. This result
is reasonable because d3 includes only intermolecular contact. In
the histogram of Figure 7b, it is recognized that not only d1 but
also d3 lies predominamtly between 2.7 and 2.9 Å, the commonly
(b) Generation of Dipole in >CdO HOÀ Hydrogen
3 3 3
Bonding System
accepted distance for O (H)O hydrogen bonding. Favorable
3 3 3
a Structural parameters: hydrogen bonding O---O distance, 2.776 Å.
distance of d3 is clearly shown in the histogram of the distribution
of d1 over d3. The search of structure for this fragment, cluster P,
gives 655 hits, which is 3.4% of data set B. The structures
occurring in cluster P should be designated as four-centered
bifurcated hydrogen bonding. It is interesting to note that the
appearance of diamond arrangement (d1 = d2 = d3 = d4) as shown
in Figure 9c, which should be designated as true four-centered
bifurcated hydrogen bonding, is rather rare with only 5 hits in 655
hits. Thus, most four-centered bifurcated hydrogen bonding is in
the alignment of a paralellogram of four oxgen atoms.
dipoleÀdipole contact O O distance, 3.036 Å. (Cd)O O(dC):
3 3 3
3 3 3
3.818 Å. Dihedral angle: (CdO)
(OdC); 180°, CdO
O
O;
3 3 3
3 3 3 3 3 3
O(H) O(dC)
133.10°, CÀO
O
O; 142.98°. (Cd)O
3 3 3 3 3 3 3 3 3
3 3 3
angle: 98.00°.
Scheme 3. Search Fragment of Four-Centered Alignment of
the Oxygen Atoms in Two >CdO (H)OÀ Hydrogen
3 3 3
Bonding Systemsa
Scheme 3 indicates that the longer d3 becomes, the wider all-
planar antiparallel alignment spreads. This might reflect the
occurrence of centrosymmetric crystals, which must necessarily
comprise antiparallel >CdO (H)O- fragments in packing
3 3 3
structures. However, looking more closely at Figure 7a, the
existence of another high scattering region, cluster Q, can be
recognized at 2.6À2.9 Å for d1 and at 3.3À4.0 Å for d3. In
particular, for d3, pronounced appearance can be seen clearly
from the histogram shown in Figure 7b. Cluster Q includes 2484
hits and is 12.9% of data set B. We assume that the structures
scattered in cluster Q are not necessarily due to packing require-
ments from centrosymmetry but rather result from participation
of particular intermolecular interactions, which exert a long-
range force, that is, dipoleÀdipole interaction. Thus, the motif
involved in the structure of cluster Q would be extracted as four-
centered quasi-bifurcated hydrogen bonding. The distance d1,
that is, the hydrogen bonding distance, tends to shift to shorter
distances in cluster Q as compared with that in cluster P.
a (a) Definition of geometrical parameters, d1, d2, d3, and d4, for search
data set A; (b) d1 = d2, d3 = d4: all-planar parallelogram arrangement of
four oxygen atoms, affording four-centered quasi-bifurcated hydrogen
bonding; (c) d1 = d2 = d3 = d4: true four-centered bifurucated hydrogen
bonding. (b) and (c) are included in data set B.
(1)(EtOH) may not be regarded as typical four-centered bifur-
cated hydrogen bonding but could be designated as quasi-bifurcated
hydrogen bonding. Thus, this motif may be interpreted by
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Figure 7. (a) Scatter plots of d1 vs d3: d1 is the O(H) O distance in a hydrogen bond and d3 is that of an intermolecular contact. (b) Histogram
3 3 3
showing distribution of d3 (= d4). (c) Scatter plots of d3 vs the dihedral angle (ϕ1) made by the CdO, CÀC(dO), and O O(dC) bonds.
3 3 3
This observation could support the participation of dipoleÀdi-
pole interactions in a quasi-bifurcated hydrogen bonding system
because it seems to be reasonable that the enhanced polarization
of the carbonyl group due to dipoleÀdipole interaction should be
advantageous also for hydrogen bonding (Scheme 2b). It would
be reasonable to assume that dipoleÀdipole interaction gradually
weakens beyond 4 Å, at which point the requirements for
centrosymmetric packing become operative.
van der Waals radii of the carbonyl oxygen in the direction along
π-orbital is 1.6À1.7 Å.12 On the other hand, hydrogen bonding
interaction would be unfavorable over 2.8 Å of the O
O
3 3 3
distances because the van der Waals radii of the hydrogen bonding
carbonyl oxygen is 1.4 Å in the carbonyl plane.12
Powder X-ray Diffraction Analysis of Solvent-Free 1. Upon
heating (1)(CH2Cl2) at 120 °C for 30 min, the guest CH2Cl2
molecules are released and the original single crystals become
opaque. It was revealed based on X-ray diffraction studies that
the resulting polycrystalline solid is a new crystalline phase
(Figure 8). As is the case in many host molecules, the crystal-
lization of 1 from solution always gave inclusion crystals but not
guest-free crystals. Thus, this new guest-free phase could only be
obtained by the desolvation process. Because the desolvation
process gave the polycrystalline solid, the crystal structure of
solvent-free 1 was analyzed from powder X-ray diffraction
(XRD) data using the direct space strategy followed by the
Rietveld refinement.13 Figure 9 shows the results of the final
Rietveld refinement of desolvated crystals of 1. The crystal
adopts an orthorhombic crystal system in space group P212121.
Thus, the solvent-free crystals of 1 are still in a chiral crystalline
phase, which arises from helical arrangement of conformation-
ally fixed molecules of 1.
It is interesting to note that there is a gap between cluster P and
Q , wherein neither hydrogen bonding nor close O O contact
3 3 3
is favorable. This observation could be rationalized based on
preferential directions of approach between the oxygen atoms for
dipoleÀdipole interaction: the hydroxyl oxygen should be posi-
tioned in the direction perpendicular to the carbonyl plane in
contrast to hydrogen bonding in which the oxygen lies close to a
carbonyl oxygen lone pair direction and hence in the carbonyl
plane. We obtained another scatter plot, showing dependence of
d3 on dihedral angle (ϕ1) made by the CdO, C(dO)ÀC, and
O
O(dC) bonds (Figure 7c). In Figure 7c, high scattering
3 3 3
region for d3 responsible for dipoleÀdipole interaction is con-
centrated around ϕ1= (90°, while d3 responsible for hydrogen
bonding is around 0° and 180°. Thus, it would be reasonable to
assume that the low scattering of d3 in 2.8À3.2 Å region could be
caused by the closest limit of the O O van der Waals contact
The most characteristic feature of the desolvated crystals is the
collapse of the dimeric unit of 1 found in solvate crystals. One of
3 3 3
in direction perpendicular to the carbonyl plane, because the
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Figure 8. Powder X-ray diffraction pattern of (a) (1)(CH2Cl2) and (b)
after desolvation of (1)(CH2Cl2).
Figure 11. TG and DTA profiles of (1)2(benzene)3.
Figure 9. Rietveld refinement plot for desolvated 1.
Figure 12. Temperature-dependent FT-IR spectra of (1)2(benzene)3
in the 3100À3700 cmÀ1 region recorded by lower shift with raising the
temperature from 60 to 160 °C (5 °C minÀ1).
those observed on the desolvated sample of 1, for which the
crystal structure has been determined by applying the Rietveld
method. This result means that the desolvated crystals, not
depending on the included guest molecules, are all in the same
crystal structure, that is, in space group P212121. The TD curves
are characterized by an initial endotherm corresponding to guest
release, followed by a second endotherm due to the melting of
the host compound at 221 °C, as depicted in Figure 11 for
(1)2(benzene)3. In the temperature-dependent IR spectra, the
temperature of guest release was evaluated from changes in the
intensities of the OH absorption band, which showed good
agreement with the values obtained from TD experiments.
Figure 12 shows the results for (1)2(benzene)3, which gives
relatively simple results because of the involvement of only
interhost hydrogen bonding.
On release of the solvent molecules, the chiral crystal lattice
of P21 in (1)(CH2Cl2) is kept without conversion to race-
mic crystals. In the case of (1)2(benzene)3, (1)(acetone), and
(1)(EtOH), however, their achiral space groups are converted to
chiral P212121 after the release of the guest molecules despite the
absence of a 21 substructure. The solid-state transformation of a
racemic compound into a conglomerate is rarely encountered, in
contrast to the reverse conversion.14 Much more rarely encoun-
tered is the appearance of chiral crystals from achiral molecules.15
Figure 10. X-ray crystal structure of guest-free crystal of 1.
the hydroxyl groups is connected to its translation-related mol-
ecules via C=O HÀOÀ hydrogen bonding (O O: 2.81 Å)
3 3 3
3 3 3
to form an infinite one-dimensional (1-D) chain along the c-axis
(Figure 10), and the other hydroxyl group forms a helical
molecular arrangement along the b-axis. Taking into considera-
tion that noparticular heteromolecular interactions occur between
1 and CH2Cl2 in (1)(CH2Cl2) crystals, one might assume that
topology with respect to the interhostÀmolecular interaction
network is retained after the loss of solvent molecules. However,
this is not true, as noted above; the dimeric unit is not maintained
in desolvated crystals.
Phase Change with Guest Release. The phase changes that
occur upon desolvation of other solvate crystals were monitored
by powder XRD, thermal analysis (TG and TD), and tempera-
ture-dependent IR spectra. All the polycrystalline crystals result-
ing from guest release showed the same XRD and IR data as
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Thus, these results provide an example of the transformation
of achiral hostÀguest inclusion crystals into chiral crystals
of the host compound by guest elimination, wherein the resulting
homochirality arises from freezing the conformation in achiral
molecules.
guest species): Found. C, 81.84%. H, 4.65%. Calcd for C33H22O4; C,
82.14%. H, 4.60%.
Preparation of Clathrate Crystals of 1. Compound 1 was
dissolved by heating in a minimum amount of the guest solvent. The
solution was placed in a hot oil bath to prevent it from rapid cooling and
to ensure crystallization of the inclusion compound. After storage for
12 h at room temperature, crystals were collected by suction filtration
and dried. The host-to-guest stoichiometric ratios were determined by
1H NMR and TG analysis.
’ CONCLUSIONS
As a new host compound for crystalline hostÀguest inclusion
complexes, 2,2-bis(4-hydroxy-3-phenylphenyl)-1H-indene-
1,3(2H)-dione (1) was prepared; it bears both hydrogen-bond
donor and acceptor sites and adopts a scissors shape. Compound
1 forms crystalline inclusion complexes represented as (1)-
(acetone), (1)(CH2Cl2), (1)(EtOH), and (1)2(benzene)3. Their
crystal structures were characterized as a supramolecular synthon
Single-Crystal X-ray Crystallographic Studies. X-ray analysis
was performed for a single crystal coated with adhesive immediately after
it was taken out of solution. X-ray diffraction data were collected on a
Rigaku RAXIS RAPID imaging plate area detector with graphite
monochromated MoÀKR radiation (λ = 0.7107 Å). Diffraction data
were collected at room temperature (23 °C) except for (1)(EtOH). The
crystal structures were solved by the direct method using SIR92 and
refined by the full-matrix least-squares method.16 Non-hydrogen atoms
were refined anisotropically. Coordinates of hydrogen atoms bonded to
each oxygen atom were determined from a difference Fourier map and
refined isotropically. Other hydrogens were placed at calculated posi-
tions with CÀH = 0.95 Å and refined using the riding model. All
calculations were performed using the CrystalStructure 3.8 crystallo-
graphic software package.17,18 Structural parameters are listed in Table 1.
Crystal data and other experimental details have been deposited at the
Cambridge Crystallographic Data Centre (CCDC). (1)2(benzene)3:
CCDC-796554. (1)(acetone): CCDC-796557. (1)(EtOH): CCDC-
796556. (1)(CH2Cl2): CCDC-796555.
with a cyclic head-to-tail dimer linked by CdO HO comple-
3 3 3
mentary hydrogen bonding in all crystals. Another characteristic
feature recognized in (1)(EtOH) is the occurrence of four-
centered quasi-bifurcated hydrogen bonding. This hydrogen
bonding motif has been revealed to be quite general as probed
in CSD research. The structures of desolvated polycrystalline
solids were elucidated by ab initio structure determination from
powder XRD data followed by Rietveld refinement. In the
desolvated crystals, the complementary hydrogen bonds forming
the dimeric unit of 1 in the solvated crystals, collapse, and a 1-D
chain of 1 is formed by linkage of intermolecular >CdO
3 3 3
(H)OÀ hydrogen bonds at one site. In (1)(acetone) and
(1)(EtOH), the formation of chiral crystals from achiral crystals
was accomplished by thermal elimination of guest molecules
from hostÀguest inclusion crystals.
Powder X-ray Diffraction. Synchrotron powder X-ray diffraction
data for the polycrystalline sample of desolvated 1 were recorded at
ambient temperature on beamline 4B2 (parallel beam optics) at the PF
synchrotron facility at a wavelength of 1.196098(5) Å. The sample was
loaded into a borosilicate glass capillary (2.0 mm diameter) and used for
the diffraction measurement in the transmission mode. The powder
XRD pattern was indexed using the program DICVOL04.19 Structure
solution was carried out using the simulated annealing method incor-
porated in the program DASH.20 The best structure obtained in the
structure solution calculation was used as the initial structural model for
Rietveld refinement, which was carried out using the GSAS program.21
Crystal data for desolvated 1: C33H22O4, P212121, a = 21.60117(18) Å,
’ EXPERIMENTAL SECTION
General Information. The 1H NMR (500 MHz) and 13C NMR
(125 MHz) spectra were recorded using a JEOL R-500 spectrometer.
Chemical shifts are given in δ values (ppm) using TMS as the internal
standard. Mass spectra were taken on a Shimadzu GCMS-QP5050A
mass spectrometer. Elementary combustion analyses were recorded
using a Yanaco CHN CORDER MT-6 analyzer. Column chromatogra-
phy was carried out on silica gel (Merck 60N spherical).
b = 12.83936(12) Å, c = 8.86864(6) Å, V = 2459.67(4) Å3, Z = 2, Dcalc
=
1.303 g/cm3, R(F**2) = 0.05861. CCDC-821644.
Database Searches. Database searches were carried out using
CSD version 5.32 (November 2010 + 1 update; 525,095 entries)22 using
the program ConQuest (ver. 1.12).23 Data sets for the cyclic and
alternate arrangements of oxygen atoms in carbonyl and hydroxyl groups
Temperature-dependent FT-IR spectra were recorded on a JASCO
FT/IR-6100 FTIR spectrometer equipped with an IR microscope, IRT-
5000, for samples compressed in KBr disks. The temperature was raised
5 °C per minute from ca. 50 to 170 °C. Thermogravimetry (TG) and
differential thermal analysis (DTA) were performed on a Rigaku TG-
DTA system at a heating rate of 20 °C minÀ1. Sample weights were ca.
5 mg. Platinum sample pans with loose lids were used in the TG
experiments, and aluminum sample pans with crimped but vented lids
were used in the TDA experiments.
Synthesis of Host Compound 1. 2,2-Bis(4-hydroxy-3-phenylphenyl)-
1,3-indandione (1) was prepared by the reaction of ninhydrin with
o-phenylphenol. Ninhydrin (1.8 g, 10 mmol) and 2-phenylphenol
(3.4 g, 20 mmol) were heated at 80À90 °C along with a drop of H2SO4
in acetic acid (20 mL) for 6 h. Workup of the reaction mixture,
including extraction with CH2Cl2, washing, drying (MgSO4), and
evaporation of the solvent under reduced pressure, yielded a crude
product that was purified by column chromatography on silica gel
(dichloromethane as eluent) to provide 1 in 70% yield. 1H NMR (500
MHz, CDCl3): δ 5.23 (2H, s), 6.92 (2H, d, J = 8.5 Hz), 7.15 (2H, d, J =
2.5 Hz), 7.21 (2H, dd, J = 8.5, 2.5 Hz), 7.35À7.41 (6H, m), 7.44À7.47
(4H, m), 7.88 (2H, m), 8.08 (2H, m). 13C NMR (125 MHz, CDCl3):δ
66.3, 116.1, 124.2, 128.0, 128.2, 129.1, 129.2, 129.7, 130.4, 130.4,
136.2, 136.6, 141.5, 152.1, 200.2. Anal. (for the sample after loss of
were generated using criteria of the alternate O O distances of
3 3 3
2.5 3.2 Å (d1 and d3) and 2.5 6.0 Å (d2 and d4), eliminating
3 3 3
3 3 3
structures having: (a) a crystallographic R factor > 10% and (b)
crystallographic disorder. To this data set, designated as data set A,
secondary search criteria were applied to fill d1 = d3 and d2 = d4 and the
sum of the internal angles being equal to 360° within errors to provide
data set B. Data set A includes 56715 structural fragments (13 234
entries) and data set B includes 19354 fragments (8813 entries).
’ ASSOCIATED CONTENT
S
Supporting Information. X-ray crystallographic reports
b
(CIF) are available free of charge via the Internet at http://
pubs.acs.org.
’ AUTHOR INFORMATION
Corresponding Author
*E-mail: kobayak@josai.ac.jp.
4051
dx.doi.org/10.1021/cg200554f |Cryst. Growth Des. 2011, 11, 4044–4052

Crystal Growth & Design
ARTICLE
’ ACKNOWLEDGMENT
H.; Koshima, H.; Miyahara, I.; Hirotsu, K. J. Chem. Soc., Perkin Trans. 2
1997, 1877.
This work was supported by Grants-in-Aid for Scientific
Research (C) from MEXT (Nos. 21550048 and 21550008).
Part of this work was performed under the approval of the
Photon Factory Program Advisory Committee (Proposal No.
2009G658).
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