Host polymorphs and crystalline host-guest complexes of 3,3′-bis(9-hydroxy-9-fluorenyl)biphenyl

Article abstract of DOI:10.1021/cg400707s

The diol host compound 2 featuring a structure with two 9-fluorenol moieties attached in 3,3′-position to a biphenyl core unit has been synthesized and is shown to form crystalline inclusion complexes with organic guest molecules. Aside from the single-crystal X-ray structures of unsolvated 2 in two polymorphous forms (2A, 2B), structures of five inclusion compounds with 1,4-dioxane (2a), DMSO (2b), diethylamine (2c), acetic acid (2d), and ethyl acetate (2e) are described and comparatively discussed in the interaction behavior including corresponding host compounds with different attachment mode of the biphenyl unit and the diphenylhydroxymethyl-substituted equivalent.

Full text of DOI:10.1021/cg400707s

Article
pubs.acs.org/crystal
Host Polymorphs and Crystalline Host−Guest Complexes of 3,3′-
Bis(9-hydroxy-9-fluorenyl)biphenyl
,†
,†
‡
,‡
Konstantinos Skobridis,* Vassiliki Theodorou,* Wilhelm Seichter, and Edwin Weber*
†
Department of Chemistry, University of Ioannina, GR-451 10 Ioannina, Greece
‡
̈
̈
Institut fur Organische Chemie, Technische Universitat Bergakademie Freiberg, Leipziger/Strasse 29, D-09596 Freiberg/Sachsen,
Germany
*
S Supporting Information
ABSTRACT: The diol host compound 2 featuring a structure
with two 9-fluorenol moieties attached in 3,3′-position to a
biphenyl core unit has been synthesized and is shown to form
crystalline inclusion complexes with organic guest molecules.
Aside from the single-crystal X-ray structures of unsolvated 2
in two polymorphous forms (2A, 2B), structures of five
inclusion compounds with 1,4-dioxane (2a), DMSO (2b),
diethylamine (2c), acetic acid (2d), and ethyl acetate (2e) are
described and comparatively discussed in the interaction
behavior including corresponding host compounds with
different attachment mode of the biphenyl unit and the
diphenylhydroxymethyl-substituted equivalent.
INTRODUCTION
Scheme 1. Compounds Studied in This Paper
■
1
−3
Crystalline inclusion chemistry, rated as an important subfield
4
−7
of crystal-engineering,
is a topic of actual interest in view of
various scientific and practical aspects such as compound
8
−11
separation and storage.
Host molecules being endowed
with this salient property have been developed by using specific
design strategies that give rise to different types of host
1
2−15
structures.
Among these, the bisfluorenol hosts show
particular efficiency in the formation of crystalline inclusion
1
6
compounds. This is produced by the bulky fluorenol groups
being attached to a rigid central unit mostly representing a
biphenyl moiety. Numerous inclusion compounds of bisfluor-
enol hosts, such as 1 and 3 (Scheme 1), featuring 2,2′- and 4,4′-
substitution of the biphenyl, respectively, have been isolated and
studied via crystal structure analysis indicating specific behavior
16−22
of guest inclusion depending on the substitution pattern.
Comparative investigation was also done involving closely
related hosts where the terminal phenyl moieties are not
covalently bonded as in the fluorene case, thus giving the phenyl
23
rings an added degree of conformational freedom. Moreover,
host derivatives with elongated 2,2″-[1,1′:4′,1″]-terphenylene
instead of 2,2′-biphenylene central moiety revealed another
structural parameter to influence inclusion property. However,
inclusion formation of the 3,3′-substituted host analogue of the
biphenylene bisfluorenol type, that is, 2 (Scheme 1), has neither
been examined nor even synthesis of the host compound
described to explore characteristics of inclusion behavior caused
by this particular substitution pattern.
24
(
Scheme 1) that involve guests of different functionality (proton
donor and acceptor compounds of varied polarity). Furthermore,
we make a comparison between the structures formed of the
present host and known structures of positionally related host
compounds or having freely rotating phenyl rings instead of
Here, we describe preparation of the host compound 2 and
report crystal structures covering two polymorphs of the solvent
free host (2A, 2B) and five inclusion compounds of 2 (2a−2e)
Received: May 7, 2013
Revised: June 24, 2013
©
XXXX American Chemical Society
A
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Article
Scheme 2. Synthesis of Host Compound 2
fluorene moieties showing potential behavior pattern created by
the 3,3′-substitution mode.
moieties, respectively (Table 2). The crystal structures are
composed of O−H···O bonded molecular chains [O(2)−H(2)···
O(1) 2.16 Å, 170°; 2.08 Å, 173°]. A packing excerpt of the
orthorhombic form 2A viewed down the crystallographic c-axis is
depicted in Figure 3. Although the chain structures in the
polymorphs 2A and 2B appear identical, the crystal structures
reveal marked differences regarding the modes of interchain
association (Table 3). In both cases, interconnection of the
supramolecular strands occurs by the remaining OH hydrogens
RESULTS AND DISCUSSION
■
Host Synthesis. The host compound 3,3′-bis[9-hydroxy-9-
fluorenyl]biphenyl (2) was synthesized by lithiation (n-BuLi/
Et O) of 3,3′-dibromobiphenyl and subsequent reaction with 9-
2
fluorenone. The starting compound 3,3′-dibromobiphenyl was
prepared from o-nitrobromobenzene by reduction of the
corresponding hydrazo compound, followed by rearrangement
to the benzidine and deamination of the bis(diazonium) salt with
26
via O−H···π interactions with fluorenyl units acting as
acceptors [orthorhombic form O(1)−H(1)···C(30) 2.88 Å,
25
1
54°; monoclinic form O(1)−H(1)···C(31) 2.76 Å, 162°].
27
hypophosphorous acid according to the literature procedure.
An illustration of the synthetic route is given in Scheme 2.
Intermolecular arene interactions of the C−H···π type play a
significant role in the orthorhombic polymorph 2A, whereas the
crystal structure of the monoclinic form 2B is stabilized by edge-
X-ray Structural Study. To elucidate the inclusion behavior
of the new diol host 2, a large number of crystallization
experiments have been carried out using solvents of various
classes of compounds with different polarity and proton donor/
acceptor properties. Unfortunately, good quality crystals which
could be structurally characterized by X-ray diffraction experi-
ments were obtained only on a limited scale. Apart from two
solvent-free crystals being polymorphs of 2 (2A and 2B), they
involve the inclusion compounds 2·1,4-dioxane (1:3) (2a), 2·
28,29
to-face arene interactions as well as face-to-face interactions
with a mean distance of 3.28 Å between interacting fluorenyl
moieties (Figure 4). It should be noted at this point that
30
according to Kitaigorodskii’s close packing concept, the more
tightly packed polymorph of a compound can be regarded as the
more stable one. Obviously, the observed packing indices of the
31
present polymorphs are in accordance with this principle, since
the orthorhombic form 2A has the higher packing coefficient
(KPI 69.1), whereas the crystal lattice of the monoclinic
DMSO (1:2) (2b), 2·HNEt (1:2) (2c), 2·CH COOH (2:1)
2
3
(
2d), and 2·CH COOC H (1:1) (2e) (Scheme 1). ORTEP
3 2 5
drawings of the molecular structures with the numbering of
relevant atoms are presented in Figures 1 and 2, while the
packing diagrams are shown in Figures 3−7. Crystallographic
data, selected conformational parameters and information
regarding hydrogen bond interactions in the crystals are listed
in Tables 1−3. Because of the high content of aromatic building
blocks, the conformation of the host molecule can be described
by a set of dihedral angles between the plane fragments
designated as A-D in the figures showing the molecular
illustrations.
3
polymorph 2B (KPI 65.0) contains voids of 83.1 Å per unit
cell amounting to 4.4% of the unit cell volume.
The 1:3 inclusion compound of 2 with 1,4-dioxane (2a)
crystallizes in the space group P-1 with one-half of the host
molecule and one and a half molecules of solvent in the
asymmetric part of the unit cell. The molecular structure is
displayed in Figure 1b. According to inversion symmetry, the
biphenyl unit of the host molecule is perfectly planar. The
fluorenyl units adopt a slight distortion with a maximum atomic
distance from the best plane being 0.089(1) Å for C(10) and
Crystallization of 2 from acetonitrile yields solvent-free
crystals of the orthorhombic space group Pbca with the unit
cell containing eight molecules, specified as polymorph 2A. A
perspective view of the molecular structure is illustrated in Figure
−
0.093 Å for C(13). The representative supramolecular entities
of the crystal structure are given by O−H···O bonded 1:2 host−
guest units [O(1)−H(1)···O(2A) 1.92 Å, 175°], which are
further associated by the second oxygen of this guest molecule to
form infinite strands [C(4)−H(4)···O(1A) 2.64 Å, 135°]
1a. On the other hand, crystal growing of 2 from chloroform or
methacrylic acid resulted in a second unsolvated crystal structure
of the polymorph 2B, which has the monoclinic space group P21/
c with four molecules in the unit cell. In both of these
polymorphs, the geometric features of the molecules are similar
which is reflected by twist angles of 44.1(1) and 41.3(1)°
between the rings of the biphenyl part and interplanar angles of
(
Figure 5). These hydrogen bonds lead to formation of 24-
6
32,33
membered ring motifs of graph set R4
as integrated parts of
the chain structure, each created by a pair of solvent molecules
containing the acceptors (O atoms) and one fluorenol unit of
two host molecules in each case containing the donors (OH and
CH group). The remaining solvent molecules are located on
60.2(1) and 55.5(1)° formed by the pairs of the fluorenyl
B
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Figure 1. ORTEP plots of the solvent-free structure 2 (orthorhombic form) (a), 2·1,4-dioxane (1:3) (2a) (b), and 2·DMSO (1:2) (2b) (c). Thermal
ellipsoids are drawn at the 50% probability level. Broken lines represent hydrogen bond interactions.
interstitial places of the crystal lattice and are excluded from
directed noncovalent bonding.
Crystallization of 2 from DMSO yields an 1:2 inclusion
compound of the space group P-1 with one host molecule and
C
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Figure 2. ORTEP diagrams of the inclusion structures 2·diethylamine (1:2) (2c) (a), 2·acetic acid (2:1) (2d) (b), and 2·ethyl acetate (1:1) (2e) (c).
Thermal ellipsoids are drawn at the 50% probability level. Broken lines represent hydrogen bond interactions.
2
6
two molecules of solvent in the unit cell. In a similar fashion as in
the aforementioned case, the crystal structure of 2b is composed
of 1:2 host−guest units with the oxygen of the guest molecules
hydrogen bonded to the hydroxy groups of the host [O(1)−
H(1)···O(1A) 2.04 Å, 163°] (Figure 1c). Association of these
complex units is accomplished by weak C−H···O interactions
with the hydroxy oxygens of the host [C(4)−H(4)···O(1) 2.62
Å, 141°] and the oxygen atom of the solvent molecule acting as
acceptors [C(10)−H(10)···O(1A) 2.47 Å, 173°]. This bifur-
cated coordination mode of the solvent oxygen gives rise to
D
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Figure 3. Packing excerpt of the solvent-free crystal structure of 2 (orthorhombic form) viewed down the crystallographic c-axis. Broken lines represent
O−H···O hydrogen bonds, broken double lines O−H···π interactions.
2
4
32,33
formation of ring motifs of the graph set R (16).
The crystal
for C(26A) and C(28A). The crystal structure of 2d is
structure (Figure 6a) is constructed of infinite supramolecular
strands running along the 111 direction. As the crystal lacks
arene···arene contacts, interstrand interactions are reduced to
van der Waals forces.
characterized by extended tricyclic systems of hydrogen bonds
(Figure 7a) each being composed of two symmetry related rings
5
5
of the graph set R (12), which comprise the hydroxy groups of
four host molecules and the carboxyl group of one solvent
molecule. The acetic acid also participates in a second
supramolecular ring motif which is created by a C−Hmethyl···
The 1:2 host−guest compound of 2 with diethylamine (2c)
crystallizes in the monoclinic space group P2 /n with Z = 2, that
1
is, the host molecule adopts inversion symmetry (Figure 2a).
Because of the distinctive donor/acceptor ability of the crystal
components, infinite strands of host and guest molecules are the
basic supramolecular entities of the crystal structure. Within a
given strand, the amino group of two solvent molecules and one
OC bonded dimer of carboxylic acid molecules following the
2
2
graph set R (8) [C(2B)-H(2B1)···O(1B) 2.54 Å, 164°]. As is
evident from Table 3, a large number of C−H···π arene
interactions [d(H···π)2.62−2.84 Å] complete the pattern of
intermolecular interactions.
OH group of two diol molecules create cyclic hydrogen bonded
Crystallization of 2 from ethyl acetate yields colorless blocks of
the monoclinic space group C2/c (Z = 8) which turned out to be
a 1:1 solvent complex 2e, the structure of which is displayed in
Figure 2c. The host molecule adopts an elongated geometry with
a twist angle of 36.8(1)° between the aromatic rings of the
biphenyl element and an interplanar angle of 31.5(1)° between
the fluorenyl units. The carbonyl oxygen of the solvent molecule
acts as a bifurcated acceptor, as it is coordinated to one of the
hydroxy hydrogens of the host molecule [O(2)−H(2)···O(1A)
1.96 Å, 152°] and by a nonconventional hydrogen bond to an
aryl hydrogen of a second host molecule [C(2)−H(2A)···O(1A)
2.54 Å, 166°]. The second hydroxy group of the host participates
in host−host association [O(1)−H(1)···O(2) 2.04 Å, 163°]. In
this way, the crystal structure of 2e (Figure 7b) contains infinite
4
motifs of the graph set R (8) [O(1)−H(1)···N(1A) 1.96 Å,
4
177°; N(1A)−H(1A)···O(1) 2.22(2) Å, 162(1) °]. As depicted
in Figure 6b, molecules of adjacent chains are arranged nearly
perpendicular to one another thus enabling intensive interstrand
association via C−H···π interactions [d(H···π) = 2.69−2.86 Å].
The inclusion compound of 2 with acetic acid (2:1) (2d)
crystallizes in the monoclinic space group C2/c with the
asymmetric part of the unit cell containing two crystallo-
graphically independent host molecules and one molecule of
solvent (Figure 2b). The conformations of the host molecules
basically differ from those found in the inclusion structures 2a−
2
c but resemble those of the unsolvated crystal structures. The
aromatic rings of the biphenyl element are twisted at angles of
2.3(1) and 39.0(1)°, the interplanar angles formed by the pairs
4
molecular strands in which the molecules create cyclic hydrogen
2
3
of the fluorenyl units are 60.5(1) and 64.8(1)°, respectively.
Because of packing and coordination effects, the fluorenyl
moieties deviate to a more or less degree from planarity and show
a marked distortion for the fluorenyl D′ with largest atomic
distances from its mean plane being −0.105(2) and 0.086(2) Å
bonded motifs [graph set notation R (9)]. The supramolecular
chains are interlinked by C−H···π type interactions.
Comparative Study of the Crystal Structures Including
Isomeric and Related Hosts. As mentioned at the beginning,
the main object of this study aims to identify distinctive features
E
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Table 2. Relevant Conformational Parameters of the Compounds Studied
2
A
2B
2a
2b
2c
2d
2e
a
dihedral angles (deg)
mpla(A)−mpla(B)
mpla(B)−mpla(C)
mpla(C)−mpla(D)
mpla(A)−mpla(D)
mpla(A′)−mpla(B′)
mpla(B′)−mpla(C′)
mpla(C′)−mpla(D′)
mpla(A′)−mpla(D′)
80.5(1)
44.1(1)
73.7(1)
60.2(1)
77.3(1)
41.3(1)
76.1(1)
55.5(1)
83.1(1)
80.1(1)
84.8(1)
78.3(1)
42.3(1)
76.8(1)
60.5(1)
77.7(1)
39.0(1)
78.5(1)
64.8(1)
87.8(1)
36.8(1)
82.5(1)
31.5(1)
torsion angles (deg)
169.0(1)
C(14)−C(13)−O(1)−H(1)
C(24)−C(26)−O(2)−H(2)
−88.0(1)
55.5(1)
−90.8(1)
54.9(1)
−173.7(1)
172.2(1)
42.1(1)
56.3(1)
90.9(1)
−177.6(1)
C(14A)−C(13A)−O(1A)−H(1A)
C(24A)−C(26A)−O(2A)−H(2A)
−170.9(1)
−112.3(1)
a
mpla means least-squares plane through the aromatic ring. Ring A: C(1)···C(13). Ring B: C(14)···C(19). Ring C: C(20)···C(25). Ring D: C(26)···
C(38). Ring A′: C(1A)···C(13A). Ring B′: C(14A)···C(19A). Ring C′: C(20A)···C(25A). Ring D′: C(26A)···C(38A).
of the solid state structures of the host compound 2 providing the
basis for a detailed comparison with the known crystal structures
formed of the constitutionally isomeric 2,2′- and 4,4′-
elongated conformation with the hydroxy groups pointing
away from the molecular backbone resulting in a chain-like
aggregation of molecules.
16−19,34,35
difluorenol-substituted biphenyl derivatives 1
and
Unlike 2, in the inclusion structures of the 2,2′-disubstituted
host isomer 1, the molecular geometry is locked by a strong
intramolecular O−H···O hydrogen bond which enforces a helical
conformation. As a consequence, only one strong donor and
acceptor site is available for molecular association. This may
explain why formation of discrete host guest aggregates are
favored over three-dimensional molecular association via
hydrogen bonding. Nevertheless, this host compound has
proven to be very efficient in formation of crystalline inclusions
with a broad variety of organic guest solvents of different
2
0−22,36,37
3,
respectively, and making a further comparison with
the related diphenylhydroxymethyl analogous host compound
2
3
possible.
With reference to the structures of the unsolvated species, the
following distinctions can be made. Depending on whether
acetonitrile or chloroform was used as a solvent for crystal
growing, 2 was found to exist in an orthorhombic or monoclinic
crystal structure. In both cases, the molecules adopt a compact
twisted geometry which appears to be controlled by close
packing requirements rather than noncovalent bonding. The
crystal structures of the polymorphs are composed of the same
kind of O−H···O bonded strands which, however, show different
modes of interchain association comprising O−H···π and arene−
arene interactions. A similar compact molecular geometry is also
observed in the crystal structure of the unsolvated 2,2′-
1
6−18,34,35
nature
tional group containing species.
In the inclusion structures of the 4,4′-disubstituted host isomer
including oligofunctional and conjugate func-
19
2
0−22,36,37
3,
the host molecule adopts an elongated geometry
irrespective of some degree of conformational freedom. This
relatively rigid molecular geometry may explain the strong
tendency of this host to create a channel-like cavity structure with
guest-specific dimensions.
35
disubstituted biphenyl derivative 1. But unlike 2, the molecular
geometry of this latter isomer is determined by a strong
intramolecular hydrogen bond between the hydroxy groups,
which induces a helical conformation with a nearly orthogonal
twist of the biphenyl unit. The hydroxy hydrogen, not involved in
O−H···O bonding, is engaged in a relatively strong intermo-
lecular O−H···π arene contact thus creating a supramolecular
dimer as the basic structure entity. Finally, the 4,4′-disubstituted
biphenyl isomer 3 adopts an elongated conformation, which
prevents formation of intramolecular hydrogen bonding. In the
solvent-free state, the hydroxy groups of the molecule lack any
directed noncovalent bonding, so that the crystal structure seems
Another interesting way to elucidate structural relationships is
to compare the crystal structures of the bisfluorenol host 2 with
those formed of the known diphenylhydroxymethyl substituted
analogue, that is, having separate phenyl substituents instead of
23
linked ones in the fluorene moiety. The solvent-free crystal
structure of the respective host lacks molecular association via
conventional hydrogen bonding, which may be ascribed to an
enhanced shielding effect caused by the distorted terminal phenyl
rings. On the contrary, the OH groups participate in formation of
weaker O−H···π interactions, which interlink the molecules to a
three-dimensional network. Only a small number of inclusion
structures of this host system have been characterized,
comprising acetone, 2-cyclopenten-1-one, and acetic acid as
18
to be stabilized only by van der Waals forces.
The present host molecule 2 made it possible for us to isolate
and structurally study single crystals of the inclusion compounds
23
2a−2e involving guests of different shape and polarity. As a
guest component. Similar to the inclusion structures of 2, the
crystals of this particular host inclusions are constructed of
infinite hydrogen bonded strands, which, however, differ in their
patterns of host−guest aggregation. In the 1:1 host−guest
complex with acetic acid, the guest molecules create the well-
matter of principle, their crystal structures suggest considerable
conformational flexibility for the host molecule. In presence of a
highly cross-linking solvent species, as in the inclusion structure
of 2 with acetic acid (2d), the host molecule adopts a strongly
twisted conformation with a close distance of the fluorenyl units.
On the other side, in cases where the host adopts inversion
symmetry (2a−2c), as well as in the solvent inclusion of 2 with
ethyl acetate (2e), the molecule exists in an undistorted
38
known O−H···O bonded dimers, which are further linked with
host molecules to form infinite strands. On the other side, crystal
growing of 2 from acetic acid yields a 2:1 complex (2d), which is
characterized by a complicated tricyclic system of hydrogen
G
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Article
Table 3. Noncovalent Interactions in the Crystal Structures Studied
distance
atoms involved D−H···A
symmetry operator
D···A
H···A
angle D−H···A
2
A
b
O(1)−H(1)···C(30)
O(2)−H(2)···O(1)
C(15)−H(15)···O(1)
1 + x, y, z
3.660(1)
2.987(1)
2.831(1)
3.555(2)
3.729(2)
3.534(2)
3.584(2)
2.88
2.16
2.51
2.63
2.90
2.63
2.74
154
170
100
164
147
159
148
0.5 − x, −0.5 + y, z
x, y, z
a
C(9)−H(9)···cg(ring A1)
1 − x, −0.5 + y, 0.5 − z
−0.5 + x, y, 0.5 − z
0.5 − x, 0.5 + y, z
1 + x, y, z
b
C(5)−H(5)···C(10)
a
C(2)-H(2A)···cg(ring C)
C(16)−H(16)···cg(ring D2)
a
2
B
b
O(1)−H(1)···C(31)
O(2)−H(2)···O(1)
C(23)−H(23)···O(2)
C(2)-H(2A)···C(28)
C(11)−H(11)···cg(ring C)
C(15)−H(15)···C(33)
C(23)−H(23)···C(15)
C(30)−H(30)···C(3)
x, −1 + y, z
3.469(2)
2.913(1)
2.790(2)
3.600(2)
3.535(2)
3.534(2)
3.436(2)
3.563(2)
3.534(2)
2.76
2.08
2.47
2.88
2.59
2.73
2.85
2.73
2.75
162
173
100
133
171
143
121
147
141
x, 1.5 − y, 0.5+z
x, y, z
b
x, −1 + y, z
x, 1.5 − y, −0.5 + z
x, −1 + y, z
x, 1.5 − y, 0.5 + z
x, 1.5 − y, 0.5 + z
−x, 2 − y, 1 − z
a
b
b
b
a
C(35)−H(35)···cg(ring C)
2
a
O(1)−H(1)···O(2A)
C(19)−H(19)···O(1)
C(2)−H(2)···C(9)
C(4)−H(4)···O(1A)
C(9)−H(9)···O(1)
C(10)−H(10)···C(17)
1 + x, 1 + y, z
x, y, z
2.759(1)
2.710(1)
3.652(1)
3.377(1)
3.465(1)
3.561(1)
3.723(1)
1.92
2.38
2.88
2.64
2.66
2.85
2.85
175
101
139
135
143
132
154
b
−1 + x, y, z
1 − x, 1 − y, −z
1 + x, y, z
b
1 + x, 1 + y, z
2 − x, 1 − y, 1 − z
b
C(17)−H(17)···C(10)
2
b
O(1)−H(1)···O(1A)
C(10)−H(10)···O(1A)
C(4)−H(4)···O(1)
x, y, z
2.851(1)
3.415(2)
3.413(2)
2.740(2)
2.04
2.47
2.62
2.40
163
173
141
100
−x, 1 − y, −z
1 + x, y, z
x, y, z
C(19)−H(19)···O(1)
2
c
O(1)−H(1)···N(1A)
N(1A)−H(1A)···O(1)
C(19)−H(19)···O(1)
1 + x, y, z
1 − x, −y, 1 − z
x, y, z
2.803(1)
3.082(1)
2.711(1)
3.542(2)
3.576(2)
3.554(1)
3.387(1)
1.96
177
162(1)
103
2.22(2)
2.34
a
C(5)−H(5)···cg(ring B)
1.5 − x, 0.5 + y, 0.5 − z
−1 + x, y, z
0.5 + x, 0.5 − y, −0.5 + z
1.5 − x, −0.5 + y, 0.5 − z
2.72
145
a
C(3A)−H(3A2)···cg(ring A2)
2.70
148
b
C(8)−H(8)···C(18)
2.69
152
b
C(11)−H(11)···C(4)
2.86
116
2
d
O(1)−H(1)···O(2A)
O(2A)−H(2A1)···O(2)
O(1A)−H(1A)···O(1B)
O(2)−H(2)···O(1A)
O(2B)−H(2B)···O(1)
C(2B)−H(2B1)···O(1B)
C(23)−H(23)···O(2)
x, −y, −0.5 + z
x, y, 1 + z
2.853(2)
2.860(2)
2.736(2)
2.761(2)
2.700(2)
3.490(2)
2.793(2)
3.641(3)
3.589(3)
3.446(3)
3.705(3)
3.700(3)
3.489(3)
3.627(3)
3.508(3)
3.681(3)
3.551(3)
3.767(3)
3.780(3)
2.03
2.21
1.90
1.93
1.87
2.54
2.47
2.85
2.83
2.82
2.79
2.82
2.62
2.78
2.62
2.80
2.63
2.84
2.84
167
135
174
173
172
164
100
142
138
124
162
154
153
148
152
154
163
165
162
x, y, z
x, 1 − y, −0.5 + z
x, 1 + y, z
0.5 − x, 1.5 − y, 1 − z
x, y, z
b
C(9)−H(9)···C(5)
C(16)−H(16)···C(32)
0.5 − x, 0.5 + y, 0.5 − z
x, −y, 0.5 + z
x, 1 − y, −0.5 + z
−x, −y, −z
x, −y, −0.5 + z
x, −y, −0.5 + z
x, 1 − y, −0.5 + z
x, 1 − y, −0.5 + z
0.5 − x, 0.5 − y, 1 − z
x, 1 − y, 0.5 + z
x, 1 − y, 0.5 + z
x, −y, 0.5 + z
b
b
C(23)−H(23)···C(15A)
C(30)−H(30)···C(22)
C(35)−H(35)···C(10A)
b
b
a
C(2)−H(2A)···cg(ring C)
C(11A)−H(11A)···cg(ring D2′)
C(16A)−H(16A)···cg(ring D1′)
C(5A)−H(5A)···cg(ring A2)
C(2A)−H(2A2)···cg(ring C)
a
a
a
a
a
C(16)−H(16)···cg(ring D1)
C(29A)−H(29A)···C(25A)
b
H
dx.doi.org/10.1021/cg400707s | Cryst. Growth Des. XXXX, XXX, XXX−XXX

Crystal Growth & Design
Article
Table 3. continued
distance
atoms involved D−H···A
symmetry operator
D···A
H···A
angle D−H···A
2
e
O(1)−H(1)···O(2)
O(2)−H(2)···O(1A)
C(2)−H(2A)···O(1A)
C(19)−H(19)···O(1)
C(25)−H(25)···O(2)
1 + x, y, z
2.851(1)
2.730(1)
3.474(1)
2.761(1)
2.689(1)
3.685(1)
3.672(1)
2.04
1.96
2.54
2.39
2.33
2.74
2.86
163
152
166
103
101
174
144
x, 1 + y, z
x, y, z
x, y, z
x, y, z
b
C(3)−H(3)···C(18)
x, −y, −0.5 + z
x, −1 − y, 0.5 + z
b
C(4)−H(4)···C(9)
a
Means center of the aromatic ring. Ring A1: C(1)···C(6). Ring A2: C(7)···C(12). Ring B: C(14)···C(19). Ring C: C(20)···C(25). Ring D1:
b
C(27)···C(32). Ring D2: C(33)···C(38). Ring D1′: C(27A)···C(32A). Ring D2′: C(33A)···C(38A). To achieve a reasonable hydrogen bond
geometry, an individual atom instead the ring centroid was chosen as acceptor.
shown to behave as host molecule for crystalline inclusion
formation similar, in principle, to 1 and 3. This is demonstrated
by the inclusion compounds 2a−2e involving guests of different
shape and functionality, which have been isolated and
structurally studied. Nevertheless, guest free crystals could also
be obtained in two polymorphous forms (2A, 2B) when
crystallized from acetonitrile or chloroform showing that solvent
inclusion may not to happen under particular conditions. A main
statement, however, is deduced from a comparative inspection
comprising the presently studied and the known structures of the
2
,2′- and 4,4′-disubstituted host isomers, which clearly illustrates
how the connection mode of the biphenyl element, either 2,2′-,
,3′-, or 4,4′-, distinctly exercises an influence on the inclusion
3
behavior by implication of changed molecular flexibility and
supramolecular interactions including availability of the host
functional groups for the complex formation. From this point of
view, the host compound 2 is closer to 3 than to 1. This is
attributed to the high conformational rigidity in 1 because of the
strong intramolecular hydrogen bond between the hydroxyls
leading to strict mono proton donor and acceptor nature in the
host−guest interaction with reference to the coordinating
groups. By way of contrast, 2 and 3 are not restrained in this
respect giving rise to conformational flexibility and supporting
bifunctionality of the molecules. Thus, although the host
compounds of the given series 1-3 are composed of the same
building units, but in different connection, show rather
distinctive host character.
EXPERIMENTAL SECTION
General. The melting point (uncorrected) was determined with a
Reichert hot stage apparatus. The IR spectrum (cm ) was recorded
with a Perkin-Elmer FT-IR 1600 spectrometer. H and C NMR
Figure 4. Packing excerpts of the polymorphic structures of 2. (a)
Orthorhombic polymorph 2A viewed down the a-axis. Structure
domains marked by shading represent arene edge-to-face interactions.
■
−1
1
13
(
b) Monoclinic polymorph 2B viewed down the b-axis. Structure
domains marked by shading represent arene face-to-face interactions.
Broken lines represent O−H···O hydrogen bonds.
spectra were measured for solutions (Me Si as internal standard, ppm)
4
with a Bruker AMX 250 MHz spectrometer. The high resolution ESI
mass spectrum was obtained using a ThermoFisher Scientific Orbitrap
XL spectrometer.
bonds. In this remarkable coordination pattern, a pair of C−H···
OC bonded solvent molecules represent the central ring. The
carboxylic groups of these molecules also take part in the
formation of two more extended O−H···O bonded ring systems
each being formed by the OH groups of four different host
molecules.
Reactions were monitored by thin-layer chromatography carried out
on Merck silica gel 60 F254-coated plates. For column chromatography,
silica gel (Merck, particle size 0.040−0.063 mm, 230−240 mesh) was
used. All reagents were commercial products and were used without
further purification. The solvents used were purified or dried by standard
3
9
procedures. The starting compounds 2-nitrobromobenzene and
fluoren-9-one were purchased from Janssen. 3,3′-Dibromobiphenyl
2
5
was prepared according to the literature procedure.
CONCLUSION
■
Synthesis of 3,3´-Bis(9-hydroxy-9-fluorenyl)biphenyl (2). A sol-
ution of n-BuLi (1.6 M in n-hexane, 12.5 mL, 20 mmol) was added
dropwise at −78 °C under argon and under stirring to 3,3′-
dibromobiphenyl (3.10 g, 10 mmol) dissolved in dry diethyl ether (40
mL). Stirring of the mixture was continued at −20 °C for 10 min. Then,
A new bulky diol compound 2 featuring a structure with two 9-
fluorenol moieties positionally 3,3′-attached to a central biphenyl
unit that fills the gap between the known 2,2′- and 4,4′-
substituted analogues, that is, 1 and 3, has been synthesized and is
I
dx.doi.org/10.1021/cg400707s | Cryst. Growth Des. XXXX, XXX, XXX−XXX

Crystal Growth & Design
Article
Figure 5. Packing excerpt of the inclusion structure 2·1,4-dioxane (1:2) (2a) viewed down the crystallographic a-axis. Broken lines represent hydrogen
bond type interactions.
Figure 7. Packing diagrams of the inclusion structures 2·acetic acid (2:1)
(
2d) (a) and 2·ethyl acetate (1:1) (2e) (b). Broken lines represent
Figure 6. Packing diagrams of the inclusion structures 2·DMSO (1:2)
2b) (a) and 2·diethylamine (1:2) (2c) (b). Broken lines represent
hydrogen bond interactions.
hydrogen bond interactions.
(
J
dx.doi.org/10.1021/cg400707s | Cryst. Growth Des. XXXX, XXX, XXX−XXX

Crystal Growth & Design
Article
fluorenone (3.78 g, 21 mmol) in dry diethyl ether (40 mL) was added
and the mixture was kept at reflux. After completion of the reaction (20
h), which was monitored by TLC (hexane/ethyl acetate 2:1), the
(10) Organic Solid State Reactions, Topics in Current Chemistry; Toda, F.,
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(11) Metal−Organic Frameworks: Design and Application; Gillivray, L.
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reaction mixture was cooled, quenched with saturated aqueous NH Cl
4
solution and extracted with Et O (2 × 30 mL). The combined organic
(12) Weber, E. In Inclusion Compounds; Atwwod, J. L., Davies, J. E. D.,
MacNicol, D. D., Eds.; Oxford University Press: Oxford, U.K., 1991;
Vol. 4, pp 188−262.
2
extracts were dried (Na SO ) and evaporated. Recrystallization from
2
4
ethyl acetate yielded a first crop (2.20 g, 43%) of pure product. A second
crop (1.14 g, 22%) was obtained from the filtrate, which was evaporated
(13) Bishop, R. Chem. Soc. Rev. 1996, 25, 311−319.
and purified by flash chromatography on SiO column (hexane/ethyl
(14) Desiraju, G. R. In Comprehensive Supramolecular Chemistry;
MacNicol, D. D., Toda, F., Bishop, R., Eds.; Elsevier: Oxford, U.K.,
1996; Vol. 6, pp 1−22.
(15) Nangia, A. In Nanoporous Materials; Series on Chemical
Engineering; Lu, G. Q., Zhao, X. S., Eds.; Imperial College Press:
London, 2004; Vol. 4, pp 165−187.
(16) Weber, E. In Comprehensive Supramolecular Chemistry; MacNicol,
D. D., Toda, F., Bishop, R., Eds.; Elsevier: Oxford, U.K., 1996; Vol. 6, pp
2
acetate 2:1). Total yield 65% of colorless solid; mp 219−221 °C. IR
(
KBr) ν 3035 (OH), 3035 (C−H, arom.), 1599 (CC), 1446, 1282,
1
1
035; H NMR (250 MHz, CDCl ) δ 2.56 (s, br, OH, 2H), 7.28−7.50
3
13
(
m, 18H, ArH), 7.73−7.79 (m, 6H, ArH); C NMR (63 MHz, CDCl )
3
δ 83.8 (CO), 120.3, 124.4, 124.6, 124.9, 126.4, 128.6, 129.3, 139.7,
+
1
5
41.4, 143.8, 150.4 (Ar). MS (ESI) m/z calcd for [C H O + Na] :
37.6120; found [M + Na] 537.1825.
38
26
2
+
X-ray Crystallography. Crystals of the polymorphs 2A and 2B
5
(
35−592.
17) Weber, E.; Skobridis, K.; Wierig, A.; Stathi, S.; Nassimbeni, L. R.;
Niven, M. L. Angew. Chem., Int. Ed. Engl. 1993, 32, 606−608.
18) Caira, M. R.; Le Roex, T.; Nassimbeni, L. R.; Ripmeester, J. A.;
suitable for X-ray diffraction were obtained by slow crystallization of 2
from acetonitrile and chloroform, respectively. Suitable crystals of the
inclusion compounds 2a−2e were grown by slow evaporation of
solutions of 2 in the respective solvent. The intensity data were collected
(
Weber, E. Org. Biomol. Chem. 2004, 2, 2299−2304.
(19) Skobridis, K.; Theodorou, V.; Alivertis, D.; Seichter, W.; Weber,
on a Bruker APEX II diffractometer with MoK radiation (λ = 0.71073
α
Å) using ω- and ϕ-scans. Reflections were corrected for background,
Lorentz and polarization effects. Preliminary structure models were
E.; Cso
20) Weber, E.; Nitsche, S.; Wierig, A.; Cso
002, 856−872.
21) Le Roex, T.; Nassimbeni, L. R.; Weber, E. Chem. Commun. 2007,
124−1126.
22) Bourne, S. A.; Corin, K.; Cruickshank, D. L.; Davson, J.;
Nassimbeni, L. R.; Su, H.; Weber, E. New J. Chem. 2011, 35, 1556−1561.
23) Skobridis, K.; Paraskevopoulos, G.; Theodorou, V.; Seichter, W.;
̈
regh, I. Supramol. Chem. 2007, 19, 373−382.
(
̈
regh, I. Eur. J. Org. Chem.
40
derived by application of direct methods and were refined by full-
2
(
1
(
2
41
matrix least-squares calculation based on F for all reflections. The
non-hydrogen atoms were refined with anisotropic thermal parameters.
With the exception of the amino hydrogen H(1A) in the structure of 2c,
all other hydrogen atoms were included in the models in calculated
positions and were refined as constrained to bonding atoms.
(
Weber, E. Cryst. Growth Des. 2011, 11, 5275−5288.
ASSOCIATED CONTENT
(24) Klien, H.; Seichter, W.; Weber, E. CrystEngComm 2013, 15, 586−
■
5
96.
*
S
Supporting Information
(25) Snyder, H. R.; Weaver, C.; Marshall, C. D. J. Am. Chem. Soc. 1949,
X-ray crystallographic data in CIF format for the structures
reported in this paper. This material is available free of charge via
the Internet at http://pubs.acs.org.
7
1, 289−291.
(26) Desiraju, G. R.; Steiner, T. The Weak Hydrogen Bond; Oxford
University Press: Oxford, U.K., 1999; pp 29−121.
27) Nishio, M.; Umezawa, Y.; Honda, K.; Tsuboyama, S.; Suezawa, H.
CrystEngComm 2009, 11, 1757−1788.
28) Dance, I. In Encyclopedia of Supramolecular Chemistry; Atwood, J.
(
AUTHOR INFORMATION
■
*
(
Corresponding Author
E-mail: kskobrid@cc.uoi.gr (K.S.); Edwin.Weber@chemie.tu-
freiberg.de (E.W.).
L., Steed, J. M., Eds.; Dekker: New York, 2004; pp 1076−1092.
(29) Salonen, L. M.; Ettermann, M.; Diederich, F. Angew. Chem., Int.
Ed. 2011, 50, 4808−4842.
(
30) Kitaigorodskii, A. I. In Organic Chemical Crystallography;
Notes
Consultant Bureau: New York, 1961; Ch. 3.
31) PLATON, version 1.15; University of Glasgow: Glasgow, U.K.,
008.
The authors declare no competing financial interest.
(
2
(
32) Etter, M. C. J. Phys. Chem. 1991, 95, 4601−4610.
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K
dx.doi.org/10.1021/cg400707s | Cryst. Growth Des. XXXX, XXX, XXX−XXX