Molecular tectonics. Construction of porous hydrogen-bonded networks from bisketals of pentaerythritol

Article abstract of DOI:10.1021/jo026267t

2,4,8,10-Tetraoxaspiro[5,5]undecanes tetrasubstituted at the 3 and 9 positions with groups incorporating diaminotriazines can be used for the construction of extensively hydrogen-bonded networks by the strategy of molecular tectonics. Four such compounds, tectons 1-4, were made by short and efficient syntheses involving bisketalization of pentaerythritol and subsequent reactions. Unlike tectons typically used in previous studies, compounds 1-4 are flexible and chiral, and they orient four sticky diaminotriazine groups in a distorted tetrahedral geometry. Tecton 1 crystallizes from DMF/toluene as an inclusion compound of approximate composition 1·8DMF·xH₂O. In the resulting structure, each tecton participates in a total of 16 hydrogen bonds. Eight of these bonds involve four principal neighbors, and the tectons linked in this way define a distorted diamondoid network. Despite 8-fold interpenetration, 60% of the volume of the network is available for including guests. The guests are disordered and occupy parallel helical channels that have cross sections of approximately 11 × 12 A² at the narrowest points. These channels provide access to the interior of the crystals and permit guests to be exchanged quantitatively without loss of crystallinity. It is noteworthy that tecton 1, despite its flexibility, small size, and structural simplicity, is apparently unable to find a periodic three-dimensional structure in which the dictates of hydrogen bonding and close packing are satisfied simultaneously.

Full text of DOI:10.1021/jo026267t

Molecu la r Tecton ics. Con str u ction of P or ou s Hyd r ogen -Bon d ed
Netw or k s fr om Bisk eta ls of P en ta er yth r itol
He´le`ne Sauriat-Dorizon, Thierry Maris, and J ames D. Wuest*
De´partement de Chimie, Universite´ de Montre´al, Montre´al, Que´bec H3C 3J 7, Canada
Gary D. Enright
Steacie Institute for Molecular Sciences, National Research Council, Ottawa, Ontario K1A 0R6, Canada
wuest@chimie.umontreal.ca
Received J uly 31, 2002
2,4,8,10-Tetraoxaspiro[5,5]undecanes tetrasubstituted at the 3 and 9 positions with groups
incorporating diaminotriazines can be used for the construction of extensively hydrogen-bonded
networks by the strategy of molecular tectonics. Four such compounds, tectons 1-4, were made by
short and efficient syntheses involving bisketalization of pentaerythritol and subsequent reactions.
Unlike tectons typically used in previous studies, compounds 1-4 are flexible and chiral, and they
orient four sticky diaminotriazine groups in a distorted tetrahedral geometry. Tecton 1 crystallizes
from DMF/toluene as an inclusion compound of approximate composition 1‚8DMF‚xH2O. In the
resulting structure, each tecton participates in a total of 16 hydrogen bonds. Eight of these bonds
involve four principal neighbors, and the tectons linked in this way define a distorted diamondoid
network. Despite 8-fold interpenetration, 60% of the volume of the network is available for including
guests. The guests are disordered and occupy parallel helical channels that have cross sections of
approximately 11 × 12 Å2 at the narrowest points. These channels provide access to the interior of
the crystals and permit guests to be exchanged quantitatively without loss of crystallinity. It is
noteworthy that tecton 1, despite its flexibility, small size, and structural simplicity, is apparently
unable to find a periodic three-dimensional structure in which the dictates of hydrogen bonding
and close packing are satisfied simultaneously.
In tr od u ction
normally favored; instead, open networks are formed,
with significant space available for the inclusion of
guests. Because both sticky sites and cores can be varied
widely, molecular tectonics has significant potential for
creating new porous ordered materials.
Molecular tectonics is a useful strategy for creating
new ordered structures by design.1-4 It is based on the
association of special molecules, called tectons, that
interact strongly with their neighbors in well-defined
ways. Tectons can be considered to consist of peripheral
sticky sites that direct molecular association, as well as
cores that hold the sticky sites in particular orientations.
Together, these features help tectons control how their
neighbors are positioned, despite the competing effects
of other intermolecular interactions that are weaker and
less specific. When association is controlled by multiple
directional interactions, close molecular packing is not
Nominally tetrahedral cores derived from tetraphe-
nylmethane and tetraphenylsilane have been employed
extensively in molecular tectonics, as well as in other
areas of chemistry, because they have relatively rigid
structures with simple, well-defined geometries.5 For
example, derivatives of tetraphenylmethane and tet-
raphenylsilane have been designed to incorporate tetra-
hedrally directed sites for hydrogen bonding so that
association produces diamondoid networks or related
three-dimensional, four-connected structures.1,2,6 In con-
trast, little attention has been given to tectons with
conformationally flexible cores, chiral structures,4 and
distorted tetrahedral geometries, which may tend to favor
alternative architectures. In this paper, we show that
tectons 1-4, which have flexible chiral 2,4,8,10-tetraoxa-
spiro[5,5]undecyl cores, can be synthesized efficiently
from pentaerythritol by bisketalization. The presence of
four diaminotriazine groups ensures extensive intermo-
lecular hydrogen bonding, and the groups are held in
highly distorted tetrahedral orientations by the spirobi-
* Author to whom correspondence should be addressed.
(1) Brunet, P.; Demers, E.; Maris, T.; Enright, G. D.; Wuest, J . D.
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Submitted for publication. Fournier, J .-H.; Maris, T.; Wuest, J . D.; Guo,
W.; Galoppini, E. Submitted for publication. Vaillancourt, L.; Simard,
M.; Wuest, J . D. J . Org. Chem. 1998, 63, 9746. Su, D.; Wang, X.;
Simard, M.; Wuest, J . D. Supramol. Chem. 1995, 6, 171. Wuest, J . D.
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10.1021/jo026267t CCC: $25.00 © 2003 American Chemical Society
Published on Web 12/20/2002
240
J . Org. Chem. 2003, 68, 240-246

Molecular Tectonics: Construction of H-Bonded Networks
that provided analogue 5.8 In a similar way, tecton 3 was
prepared in 53% overall yield from pentaerythritol and
4,4′-dibromobenzophenone, and meta-substituted ana-
logue 4 was obtained in 58% overall yield from pen-
taerythritol and 3,3′-dibromobenzophenone.11 The syn-
theses of compounds 1-4 show that relatively complex
tectons can be prepared rapidly and efficiently from
inexpensive precursors.
Intermediate tetrabromides and tetranitriles 6-7,
9-10, and 11-14 prepared in the course of these
syntheses are also useful precursors for making other
new derivatives of 2,4,8,10-tetraoxaspiro[5,5]undecane
with applications in molecular tectonics or in other fields
of chemistry. For example, tetralithiation of tetrabromide
9, followed by the addition of CO2 and acidification, gave
a 74% yield of tetracarboxylic acid 15. Coordination to
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cyclic cores. We have found that tecton 1 crystallizes to
form an open hydrogen-bonded network with large helical
channels that provide significant space for the inclusion
of guests.
Resu lts a n d Discu ssion
Syn th eses of Tecton s 1-4. Tecton 1 was prepared
in three steps in 53% overall yield from pentaerythritol
and the known ketone 5,7 which we obtained in 68% yield
by the self-condensation of 4-bromophenylacetic acid,
induced by DCC and DMAP.8 Ketalization of compound
5 with pentaerythritol gave an 86% yield of tetrabromide
6, which was converted into the corresponding tetrani-
trile 7 in 69% yield by treatment with CuCN in hot
DMF.9 Heating tetranitrile 7 with dicyandiamide and
KOH in 2-methoxyethanol then afforded diaminotriazine
1 in 90% yield.10
(4) Holy´, P.; Za´vada, J .; C´ısarova´, I.; Podlaha, J . Angew. Chem., Int.
Ed. 1999, 38, 381.
(5) Fournier, J .-H.; Wang, X.; Wuest, J . D. Submitted for publication.
(6) For a review of diamondoid hydrogen-bonded networks, see:
Zaworotko, M. J . Chem. Soc. Rev. 1994, 23, 283.
(7) Zaugg, H.; Rapala, R. T.; Leffler, M. T. J . Am. Chem. Soc. 1948,
70, 3224.
(8) Bhandari, S.; Ray, S. Synth. Commun. 1998, 28, 765.
Meta-substituted isomer 2 was synthesized similarly
in 35% overall yield from pentaerythritol and 1,3-bis(3-
bromophenyl)-2-propanone (8), which was made in 81%
yield from 3-bromophenylacetic acid by the same method
(9) Ellis, G. P.; Romney-Alexander, T. M. Chem. Rev. 1987, 87, 779.
(10) Simons, J . K.; Saxton, M. R. Organic Syntheses; Wiley: New
York, 1963; Collect. Vol. IV, p 78.
(11) Vo¨gtle, F.; Alfter, F.; Nieger, M.; Steckhan, E.; Mavili, S. Chem.
Ber. 1991, 124, 897.
J . Org. Chem, Vol. 68, No. 2, 2003 241

Sauriat-Dorizon et al.
inclusion of guests.13 Each tecton forms hydrogen bonds
with six neighbors, creating the assembly shown in
Figures 1 and 2. Four neighbors (light gray) each form
two hydrogen bonds with the central tecton (white).
These intertectonic contacts each involve two interacting
diaminotriazines that are approximately coplanar and
hydrogen bond in the manner represented by structure
16. This motif is frequently observed in the structures
of other 2,4-diaminotriazines.2 Motif 16 involves the more
accessible N-3/N-3′ nitrogen atoms and is therefore
expected to be more stable than the alternative N-3/N-1′
and N-1/N-1′ motifs 17 and 18.
F IGURE 1. Representation of a central molecule of tecton 1
(white) surrounded by its six hydrogen-bonded neighbors. Two
hydrogen bonds are formed with each of the four neighbors
shown in light gray, creating motifs of type 16, and four
hydrogen bonds are formed with each of the two neighbors
shown in dark gray, creating distorted motifs of type 18. In
this view, the c axis is horizontal.
Formation of the N-3/N-3′ motif 16 alone does not fully
exploit the ability of diaminotriazines to form hydrogen
bonds, so the central tecton in the assembly shown in
Figure 1 also forms four hydrogen bonds with each of two
other symmetrically oriented neighbors (dark gray).
These additional interactions correspond to the less
favored N-1/N-1′ motif 18. Evidence that these interac-
tions (motif 18) are weaker than those linking the central
tecton to the four neighbors shown in light gray (motif
16) is provided by comparing the average planes of the
interacting diaminotriazine rings. In the interactions
corresponding to motif 16, the angle is only 9.1°, whereas
in those corresponding to motif 18, it is 55.9°. However,
the average hydrogen-bonded N‚‚‚N distances of type 16
observed in the structure (3.033(6) Å) are not significantly
shorter than the average of those of type 18 (3.034(6) Å).
Nevertheless, each tecton can be considered to have four
principal hydrogen-bonded neighbors (planar motif 16)
and two secondary neighbors (distorted motif 18).
As shown in structures 16-18, each diaminotriazine
incorporates two -NH2 groups, which can in principle
donate a total of four hydrogen bonds, and three hetero-
cyclic nitrogen atoms (N-1, N-3, and N-5), which can
accept a total of three hydrogen bonds. Each molecule of
tecton 1 can therefore participate in a maximum of 28
normal hydrogen bonds. Of this number, 16 are used to
construct the observed supramolecular network by com-
F IGURE 2. Detailed view of a molecule of tecton 1 (white)
with two of its six hydrogen-bonded neighbors. The one shown
in light gray forms two hydrogen bonds with the tecton shown
in white, creating motifs of type 16, and the dark gray neighbor
forms a total of four hydrogen bonds with the white tecton,
creating distorted motifs of type 18. In this view, the c axis is
horizontal, and hydrogen bonds appear as broken lines.
metals or self-association by hydrogen bonding of the
carboxyl groups should yield extended networks.
Str u ctu r e of th e Hydr ogen -Bon ded Networ k Bu ilt
fr om Tecton 1. Despite varied attempts to crystallize
tectons 1-4 and 15, crystals suitable for X-ray diffraction
could only be grown from compound 1. Crystallization
from DMF/toluene gave an inclusion compound of ap-
proximate composition 1‚10DMF‚xH2O,12 and its struc-
ture was determined by X-ray crystallography. Views of
the structure are shown in Figures 1-5. The tectons self-
associate by hydrogen bonding of diaminotriazine groups,
as expected, to form an open three-dimensional network
with significant space for both interpenetration and the
(12) Compositions were estimated by X-ray crystallography and 1H
NMR spectroscopy of dissolved samples. The amount of H2O included,
if any, could not be determined accurately by these methods.
(13) For discussions of interpenetration in networks, see: Batten,
S. R. Cryst. Eng. Commun. 2001, 18, 1. Batten, S. R.; Robson, R. Angew.
Chem., Int. Ed. 1998, 37, 1460.
242 J . Org. Chem., Vol. 68, No. 2, 2003

Molecular Tectonics: Construction of H-Bonded Networks
F IGURE 3. Representation of the interpenetrated diamondoid
networks generated by tecton 1. In this drawing, the tectons
lie at the intersections of solid lines that represent their
interactions with four neighbors by hydrogen bonding accord-
ing to motif 16. One system of 4-fold interpenetrated networks
is shown in light gray and the other in dark gray. In this view,
the c axis is horizontal.
bined formation of the N-3/N-3′ motif 16 and the N-1/N-
1′ motif 18. Hydrogen-bonding sites not used for this
purpose are available for interacting with included
guests. Other types of interactions, such as intermolecu-
lar π-π stacking, do not appear to play a major role in
determining the observed supramolecular architecture.
The network defined by tectons that interact according
to motif 16 has a distorted diamondoid geometry in which
the central spirocyclic carbon atom of each tecton is
separated from the corresponding atoms of its four
principal hydrogen-bonded neighbors by approximately
25.5 Å.6 Because of this large separation, the network is
open enough to permit extensive interpenetration, as
shown in Figure 3.13 The interpenetration can be de-
scribed as 8-fold, with successive networks related by a
displacement along the c glide plane. As a result, there
are two independent systems of 4-fold interpenetrated
diamondoid networks, each aligned with the c axis. In
the assembly shown in Figure 1, the central tecton
(white) and its four principal neighbors (light gray) belong
to one network, and the two other neighbors (dark gray)
belong to an adjacent network in the same system of
4-fold interpenetration.
Despite multiple interpenetration, the network built
from tecton 1 retains very significant volume for the
inclusion of guests. The guests were found to be highly
disordered and could not be located precisely, but the
volume available for their inclusion defines large chan-
nels aligned with the c axis. The cross sections of these
channels measure approximately 11 × 12 Å2 at the
narrowest points and are a prominent feature of Figure
4.14 The channels themselves are represented by the
surface shown in Figure 5.15 This view establishes that
the channels are parallel and roughly cylindrical, with
no significant interconnections.
F IGURE 4. View along the c axis of the network constructed
from tecton 1 showing a 3 × 3 × 2 array of unit cells.
Disordered guests are omitted, and atoms are shown as
spheres of van der Waals radii in order to reveal the cross
sections of channels.
larger than the percentage of unused space created in
normal molecular crystals by imperfect packing, which
is typically close to 30%.18 In fact, the percentage of
available volume in crystals of tecton 1 even exceeds that
occupied by water and other guests in many protein
crystals, despite the larger, more complex, and more
irregular shapes of proteins.19 Previous work has estab-
lished that one way in which tectons differ from normal
molecules is that their inherent tendency to form strong
directional interactions is typically incompatible with
efficient molecular packing. As a result, tectonic associa-
tion is predisposed to favor the formation of networks in
which significant space is available for guests. The
behavior of tecton 1 is fully consistent with these
generalizations, and the percentage of available volume
is similar to that of the most porous analogues studied
so far.1-4 This observation is noteworthy, because
tecton 1 incorporates numerous elements of conforma-
tional flexibility, associated primarily with the 2,4,8,10-
tetraoxaspiro[5,5]undecyl core20 and the benzylic sub-
stituents at positions 3 and 9. Even though tecton 1 is
flexible, small, and structurally simple, it is nevertheless
apparently unable to find a periodic three-dimensional
structure in which the dictates of hydrogen bonding and
close packing are satisfied simultaneously.
Exch a n ge of Gu ests. In the observed network, each
tecton participates in a total of 16 hydrogen bonds with
its neighbors to form a robust, well-ordered structure,
whereas the guests are disordered, potentially mobile,
and located in large channels that provide a possible
route of escape from inside the crystal. Consequently,
guests can be exchanged without loss of crystallinity, as
observed in other tectonic materials.1,2 For example,
Overall, 60% of the volume of crystals of tecton 1 is
available for including guests.16,17 This value is much
(14) The dimensions of a channel in a particular direction correspond
to the cross section of an imaginary cylinder that could be passed
through the hypothetical open network in the given direction in contact
with the van der Waals surface. Such values are inherently conserva-
tive because (1) they measure the cross section at the most narrow
constriction and (2) they systematically underestimate the sizes of
channels that are not uniform and linear.
(15) Representations of channels were generated by the Cavities
option in the program ATOMS (ATOMS, Version 5.1; Shape Soft-
ware: 521 Hidden Valley Road, Kingsport, TN 37663; www.shape-
software.com). We are grateful to Eric Dowty of Shape Software for
integrating this capacity in ATOMS at our suggestion.
(17) Spek, A. L. PLATON, A Multipurpose Crystallographic Tool;
Utrecht University: Utrecht, The Netherlands, 2001. van der Sluis,
P.; Spek, A. L. Acta Crystallogr. 1990, A46, 194.
(18) Kitaigorodskii, A. I. Organic Chemical Crystallography; Con-
sultants Bureau: New York, 1961.
(19) Quillin, M. L.; Matthews, B. W. Acta Crystallogr. 2000, D56,
791. Andersson, K. M.; Hovmo¨ller, S. Acta Crystallogr. 2000, D56, 789.
(20) Mager, S.; Horn, M.; Grosu, I.; Bogdan, M. Monatsh. Chem.
1989, 120, 735.
(16) The percentage of volume accessible to guests was estimated
by the PLATON program.17
J . Org. Chem, Vol. 68, No. 2, 2003 243

Sauriat-Dorizon et al.
F IGURE 5. Stereoscopic representation of the parallel helical channels defined by the network constructed from tecton 1. The
image shows a 2 × 2 × 2 array of unit cells viewed with the c axis vertical. The outsides of the channels appear in light gray, and
dark gray is used to show where the channels are cut by the boundaries of the array. The surface of the channels is defined by
the possible loci of the center of a sphere of diameter 6 Å as it rolls over the surface of the ordered tectonic network.15
distillation from CaH2. All other reagents were commercial
products that were used without further purification.
single crystals of estimated composition 1‚10DMF‚xH2O
and approximate dimensions 1 × 1 × 1 mm3 were
exposed to excess CH3COOC2H5 at 25 °C for 12 h. The
recovered sample remained transparent and morphologi-
cally unchanged, continued to diffract, and showed closely
similar unit cell parameters when studied by single-
1,3-Bis(4-br om op h en yl)-2-p r op a n on e (5).7 A solution of
dicyclohexylcarbodiimide (15.4 g, 74.6 mmol) and 4-(dimethy-
lamino)pyridine (2.29 g, 18.7 mmol) in CH2Cl2 (150 mL) was
stirred at 25 °C under dry N2 and treated dropwise with a
solution of 4-bromophenylacetic acid (16.1 g, 74.9 mmol) in
CH2Cl2 (150 mL). The resulting mixture was stirred at 25 °C
for 24 h, and then the precipitated solid was removed by
filtration and volatiles were removed from the filtrate by
evaporation under reduced pressure. Purification of the residue
by flash chromatography (silica, CH3COOC2H5 (30%)/hexane
(70%)), followed by crystallization from C2H5OH, gave 1,3-bis-
(4-bromophenyl)-2-propanone (5; 9.32 g, 25.3 mmol, 68%) as
a colorless solid: mp 118-120 °C (lit.7 mp 116-118 °C); IR
1
crystal X-ray diffraction. However, analysis by H NMR
spectroscopy of dissolved samples established that the
initial guest, DMF, had been replaced quantitatively by
CH3COOC2H5 to give new crystals of approximate com-
position 1‚10CH3COOC2H5‚yH2O.12 In such exchanges, a
preference for polar guests is observed, presumably
because the surfaces of the channels incorporate aromatic
rings, heteroatoms, and multiple sites for hydrogen
bonding.
Ch ir a lity of Tecton 1. Like other 2,4,8,10-tetraoxa-
spiro[5,5]undecanes, tecton 1 adopts a chiral chair-chair
conformation.20 The observed crystal structure consists
of equal numbers of the two enantiomeric conformations
of the basic spirocyclic core. Close examination of the
channels (Figure 5) reveals that each is helical and chiral,
but equal numbers of helices of opposite handedness are
present. As a result, crystals of tecton 1 grown by the
method described are not suitable for enantioselective
inclusion.
1
(NaCl) 1718 cm-1; H NMR (300 MHz, CDCl3) δ 7.46 (d, 4H,
3
3J ) 8.4 Hz), 7.02 (d, 4H, J ) 8.4 Hz), 3.69 (s, 4H); 13C NMR
(75.4 MHz, CDCl3) δ 204.2, 132.6, 131.8, 131.2, 121.2, 48.4.
1,3-Bis(3-br om op h en yl)-2-p r op a n on e (8). The product of
an analogous procedure using 3-bromophenylacetic acid (4.02
g, 18.7 mmol) was crystallized from C2H5OH to give 1,3-bis-
(3-bromophenyl)-2-propanone (8; 2.80 g, 7.61 mmol, 81%) as
a colorless solid: mp 109-111 °C; IR (NaCl) 1719 cm-1
;
1H
3
NMR (300 MHz, CDCl3) δ 7.42 (d, 2H, J ) 7.9 Hz), 7.30 (s,
3
2H), 7.20 (d, 2H, J ) 7.8 Hz), 7.08 (m, 2H), 3.72 (s, 4H); 13C
NMR (75.4 MHz, CDCl3) δ 204.1, 135.7, 132.5, 130.3, 130.2,
122.7, 48.6; MS (FAB, 3-nitrobenzyl alcohol) m/e 369.
3,3,9,9-T e t r a k is[(4-b r o m op h e n y l)m e t h yl]-2,4,8,10-
tetr a oxa sp ir o[5,5]u n d eca n e (6). In an apparatus fitted with
a Dean-Stark trap, a mixture of 1,3-bis(4-bromophenyl)-2-
propanone (5; 5.02 g, 13.6 mmol), pentaerythritol (0.920 g, 6.76
mmol), and p-toluenesulfonic acid (0.390 g, 2.26 mmol) in
benzene (50 mL) was heated at reflux for 48 h. The resulting
mixture was cooled and diluted with CH2Cl2. The solution was
extracted with saturated aqueous NaHCO3, washed with brine,
and dried over Na2SO4. Removal of volatiles by evaporation
under reduced pressure left a residue that was purified by
crystallization from CHCl3/hexane to give 3,3,9,9-tetrakis[(4-
bromophenyl)methyl]-2,4,8,10-tetraoxaspiro[5,5]undecane (6;
4.83 g, 5.78 mmol, 86%) as a colorless solid: mp 182-183 °C;
Con clu sion s
Detailed prediction of the structures of molecular
crystals remains impossible,21 but the strategy of molec-
ular tectonics gives chemists a broadly effective tool for
building new structures in which particular features can
be incorporated by design. Our observations extend the
scope of the strategy by confirming that it can be used
to construct robust hydrogen-bonded networks with
predictable properties of porosity even when the tectonic
subunits are geometrically complex and significantly
more flexible than those typically used in previous
studies.
3
1H NMR (300 MHz, CDCl3) δ 7.41 (d, 8H, J ) 8.3 Hz), 6.99
3
(d, 8H, J ) 8.3 Hz), 3.54 (s, 8H), 2.80 (s, 8H); 13C NMR (75.4
MHz, CDCl3) δ 135.0, 132.3, 131.0, 120.5, 100.2, 63.8, 39.4,
32.8; MS (FAB, 3-nitrobenzyl alcohol) m/e 837. Anal. Calcd for
C
35H32Br4O4: C, 50.27; H, 3.86. Found: C, 49.97; H, 3.79.
3,3,9,9-Tetr akis(4-br om oph en yl)-2,4,8,10-tetr aoxaspir o-
Exp er im en ta l Section
[5,5]u n d eca n e (9). An analogous procedure was carried out
using 4,4′-dibromobenzophenone (3.00 g, 8.82 mmol) and
pentaerythritol (0.590 g, 4.33 mmol). The crude product was
purified by chromatography (alumina, ether (30%)/hexane
(70%)) to give 3,3,9,9-tetrakis(4-bromophenyl)-2,4,8,10-tetra-
oxaspiro[5,5]undecane (9; 2.49 g, 3.19 mmol, 74%) as a
colorless solid: mp 219-220 °C; 1H NMR (300 MHz, CDCl3) δ
Tetrahydrofuran (THF) was dried by distillation from the
sodium ketyl of benzophenone, CH2Cl2 was dried by distillation
from P2O5, and N,N′-dimethylformamide (DMF) was dried by
(21) For a discussion, see: Gavezzotti, A. Acc. Chem. Res. 1994, 27,
309.
244 J . Org. Chem., Vol. 68, No. 2, 2003

Molecular Tectonics: Construction of H-Bonded Networks
7.46 (d, 8H, 3J ) 8.6 Hz), 7.33 (d, 8H, 3J ) 8.6 Hz), 3.81 (s,
8H); 13C NMR (75.4 MHz, CDCl3) δ 140.0, 131.7, 128.0, 122.4,
100.8, 65.1, 32.9; MS (FAB, 3-nitrobenzyl alcohol) m/e 781.
Anal. Calcd for C31H24Br4O4: C, 47.73; H, 3.10. Found: C,
47.74; H, 2.87.
3,3,9,9-T e t r a k is[(3-b r o m o p h e n y l)m e t h y l]-2,4,8,10-
tetr a oxa sp ir o[5,5]u n d eca n e (11). The product obtained by
an analogous procedure using 1,3-bis(3-bromophenyl)-2-pro-
panone (8; 1.77 g, 4.81 mmol) and pentaerythritol (0.320 g,
2.35 mmol) was purified by flash chromatography (silica, CH2-
Cl2 (50%)/hexane (50%)) to give 3,3,9,9-tetrakis[(3-bromophe-
nyl)methyl]-2,4,8,10-tetraoxaspiro[5,5]undecane (11; 1.13 g,
1.35 mmol, 57%) as a colorless solid: mp 108-110 °C; 1H NMR
(300 MHz, CDCl3) δ 7.39 (m, 4H), 7.31 (m, 4H), 7.17 (m, 4H),
(m, 4H), 3.57 (s, 8H), 2.84 (s, 8H); 13C NMR (75.4 MHz, CDCl3)
δ 138.2, 133.5, 129.6, 129.4, 129.3, 121.9, 100.2, 63.7, 39.6, 32.6;
MS (FAB, 3-nitrobenzyl alcohol) m/e 837. Anal. Calcd for
mp 147-149 °C; IR (NaCl) 2230 cm-1 1H NMR (300 MHz,
;
CDCl3) δ 7.57-7.33 (m, 16H), 3.47 (s, 8H), 2.87 (s, 8H);
13C NMR (75.4 MHz, CDCl3) δ 137.1, 135.1, 134.0, 130.4,
128.7, 112.0, 99.6, 63.5, 39.7; MS (FAB, 3-nitrobenzyl alcohol)
m/e 621; HRMS (electrospray) calcd for C39H32N4NaO4 m/e
643.23212, found 643.23153.
3,3,9,9-Tetr a k is(3-cya n op h en yl)-2,4,8,10-tetr a oxa sp ir o-
[5,5]u n d eca n e (14). An analogous procedure was carried out
using 3,3,9,9-tetrakis(3-bromophenyl)-2,4,8,10-tetraoxaspiro-
[5,5]undecane (13; 3.02 g; 3.87 mmol). The crude product was
recrystallized from C2H5OH to give 3,3,9,9-tetrakis(3-cyanophe-
nyl)-2,4,8,10-tetraoxaspiro[5,5]undecane (14; 1.58 g, 2.80 mmol,
72%) as a colorless solid: 1H NMR (300 MHz, CDCl3) δ 7.82
(m, 4H), 7.74 (m, 4H), 7.61 (m, 4H), 7.48 (m, 4H), 3.83 (s, 8H);
13C NMR (75.4 MHz, CDCl3) δ 142.0, 132.1, 130.4, 129.8, 129.7,
118.3, 113.1, 99.7, 65.1, 33.3; MS (FAB, 3-nitrobenzyl alcohol)
m/e 565.
C
35H32Br4O4: C, 50.27; H, 3.86. Found: C, 50.03; H, 3.83.
3,3,9,9-Tetr akis(3-br om oph en yl)-2,4,8,10-tetr aoxaspir o-
Tecton 1. A mixture of 3,3,9,9-tetrakis[(4-cyanophenyl)-
methyl]-2,4,8,10-tetraoxaspiro[5,5]undecane (7; 0.30 g, 0.48
mmol), dicyandiamide (0.67 g, 8.0 mmol), and powdered KOH
(0.074 g, 1.3 mmol) in 2-methoxyethanol (45 mL) was heated
at reflux for 12 h. The resulting mixture was cooled and
filtered, and the solid was extracted thoroughly with hot water.
The solid was then rinsed with CH2Cl2 and dried in vacuo to
give tecton 1 (0.41 g, 0.43 mmol, 90%) as a colorless solid: mp
>300 °C; H NMR (300 MHz, DMDO-d6) δ 8.11 (d, 8H, J )
8.1 Hz), 7.18 (d, 8H, 3J ) 8.1 Hz), 6.72 (br s, 16H), 3.60 (s,
8H), 2.95 (s, 8H); 13C NMR (75.4 MHz, DMSO-d6) δ 170.5,
167.7, 140.3, 135.3, 130.3, 127.4, 100.4, 63.0, 31.4; MS (FAB,
3-nitrobenzyl alcohol) m/e 957. Anal. Calcd for C47H48N20O4‚
4H2O: C, 54.84; H, 5.49. Found: C, 54.33; H, 5.53.
[5,5]u n d eca n e (13). An analogous procedure was carried out
using 3,3′-dibromobenzophenone (2.55 g, 7.50 mmol)11 and
pentaerythritol (0.510 g, 3.75 mmol). The crude product was
purified by chromatography (alumina, CH2Cl2 (50%)/hexane
(50%)) to give 3,3,9,9-tetrakis(3-bromophenyl)-2,4,8,10-tetra-
oxaspiro[5,5]undecane (13; 2.69 g, 3.45 mmol, 92%) as a
colorless solid: 1H NMR (300 MHz, CDCl3) δ 7.62 (m, 4H),
7.35 (m, 8H), 7.24 (m, 4H), 3.81 (s, 8H); 13C NMR (75.4 MHz,
CDCl3) δ 143.2, 131.4, 130.2, 129.2, 124.9, 122.8, 100.1, 65.2,
33.1. Anal. Calcd for C31H24Br4O4: C, 47.73; H, 3.10. Found:
C, 47.80; H, 2.90.
1
3
3,3,9,9-T e t r a k is [(4-c y a n o p h e n y l)m e t h y l]-2,4,8,10-
tetr a oxa sp ir o[5,5]u n d eca n e (7). A mixture of 3,3,9,9-tet-
rakis[(4-bromophenyl)methyl]-2,4,8,10-tetraoxaspiro[5,5]-
undecane (6; 2.57 g, 3.07 mmol) and CuCN (1.26 g, 14.1 mmol)
in DMF (200 mL) was heated at reflux for 48 h under dry Ar.
The resulting mixture was cooled and treated with a 33%
aqueous solution of ethylenediamine. The mixture was ex-
tracted with CH2Cl2, the extracts were washed thoroughly with
10% aqueous NaCN and water, and the washed extracts were
dried over Na2SO4. Removal of volatiles by evaporation under
reduced pressure left a residue that was purified by crystal-
lization from C2H5OH to give 3,3,9,9-tetrakis[(4-cyanophenyl)-
methyl]-2,4,8,10-tetraoxaspiro[5,5]undecane (7; 1.31 g, 2.11
mmol, 69%) as a colorless solid: mp 225-227 °C; IR (NaCl)
Tecton 2. An analogous procedure was carried out using
3,3,9,9-tetrakis[(3-cyanophenyl)methyl]-2,4,8,10-tetraoxaspiro-
[5,5]undecane (12; 0.43 g, 0.69 mmol) and provided tecton 2
(0.57 g, 0.60 mmol, 87%) as a colorless solid: mp >300 °C; 1H
3
NMR (300 MHz, DMDO-d6) δ 8.10 (d, 4H, J ) 7.1 Hz), 8.02
(m, 4H), 7.35 (m, 4H), 7.28 (m, 4H), 6.79 (br s, 16H), 3.53 (s,
8H), 2.93 (s, 8H); 13C NMR (75.4 MHz, DMSO-d6) δ 170.5,
167.6, 136.8, 136.6, 133.9, 130.3, 127.9, 126.1, 100.0, 63.0, 31.4;
MS (FAB, 3-nitrobenzyl alcohol) m/e 957. Anal. Calcd for
C
47H48N20O4‚6H2O: C, 53.00; H, 5.68; N, 26.30. Found: C,
53.10; H, 5.34; N, 26.82.
Tecton 3. An analogous procedure was carried out using
3,3,9,9-tetrakis(4-cyanophenyl)-2,4,8,10-tetraoxaspiro[5,5]-
undecane (10; 0.18 g, 0.32 mmol) and provided tecton 3 (0.25
g, 0.28 mmol, 88%) as a pale pink solid: mp >300 °C; 1H NMR
2228 cm-1; 1H NMR (300 MHz, CDCl3) δ 7.59 (d, 8H, J ) 8.4
3
Hz), 7.23 (d, 8H, 3J ) 8.4 Hz), 3.46 (s, 8H), 2.90 (s, 8H); 13C
NMR (75.4 MHz, CDCl3) δ 141.3, 131.6, 131.3, 129.7, 110.6,
99.9, 63.6, 40.4, 32.0; MS (FAB, 3-nitrobenzyl alcohol) m/e 621;
HRMS (electrospray) calcd for C39H32N4NaO4 m/e 643.23212,
found 643.23212. Anal. Calcd for C39H32N4O4‚1H2O: C, 73.34;
H, 5.37; N, 8.77. Found: C, 73.35; H, 5.11; N, 8.24.
3
(300 MHz, DMDO-d6) δ 8.22 (d, 8H, J ) 8.4 Hz), 7.54 (d, 8H,
3J ) 8.4 Hz), 6.76 (br s, 16H), 3.86 (s, 8H); 13C NMR (75.4
MHz, DMSO-d6) δ 169.5, 167.2, 133.1, 128.5, 127.3, 126.3,
100.5, 65.0, 33.0; MS (FAB, 3-nitrobenzyl alcohol) m/e 901.
Anal. Calcd for
Found: C, 55.19; H, 4.56.
C43H40N20O4‚1.5H2O: C, 55.66; H, 4.67.
3,3,9,9-Tetr a k is(4-cya n op h en yl)-2,4,8,10-tetr a oxa sp ir o-
[5,5]u n d eca n e (10). An analogous procedure was carried out
using 3,3,9,9-tetrakis(4-bromophenyl)-2,4,8,10-tetraoxaspiro-
[5,5]undecane (9; 0.510 g; 0.654 mmol) and CuCN (0.280 g,
3.13 mmol). The crude product was purified by chromatogra-
phy (alumina, CH2Cl2 (50%)/hexane (50%)) to give 3,3,9,9-
tetrakis(4-cyanophenyl)-2,4,8,10-tetraoxaspiro[5,5]undecane (10;
0.300 g, 0.531 mmol, 81%) as a colorless solid: IR (NaCl) 2231
Tecton 4. An analogous procedure was carried out using
3,3,9,9-tetrakis(3-cyanophenyl)-2,4,8,10-tetraoxaspiro[5,5]-
undecane (14; 0.17 g, 0.30 mmol) and provided tecton 4 (0.23
g, 0.26 mmol, 87%) as a pale pink solid: mp >300 °C; 1H NMR
(300 MHz, DMDO-d6) δ 8.42 (m, 4H), 8.15 (d, 4H, 3J ) 7.5
3
3
Hz), 7.57 (d, 4H, J ) 7.5 Hz), 7.43 (t, 4H, J ) 7.5 Hz), 6.77
(br s, 16H), 3.86 (s, 8H); 13C NMR (75.4 MHz, DMSO-d6) δ
170.2, 167.7, 142.1, 137.9, 129.1, 128.8, 127.7, 125.1, 101.0,
64.9, 33.0; MS (FAB, 3-nitrobenzyl alcohol) m/e 901. Anal.
Calcd for C43H40N20O4‚6H2O: C, 51.19; H, 5.19; N, 27.76.
Found: C, 51.10; H, 4.72; N, 28.49.
cm-1; H NMR (300 MHz, CDCl3) 7.64 (d, 8H, 3J ) 8.5 Hz),
1
7.61 (d, 8H, 3J ) 8.5 Hz), 3.84 (s, 8H); 13C NMR (75.4 MHz,
CDCl3) δ 145.5, 132.9, 126.0, 112.7, 99.8, 65.3, 32.8; MS (FAB,
3-nitrobenzyl alcohol) m/e 565. Anal. Calcd for C35H24N4O4‚
2H2O: C, 69.99; H, 4.70; N, 9.33. Found: C, 69.41; H, 3.95; N,
8.78.
Tecton 15. A solution of 3,3,9,9-tetrakis(4-bromophenyl)-
2,4,8,10-tetraoxaspiro[5,5]undecane (9; 0.24 g, 0.31 mmol) in
THF (10 mL) was stirred at -78 °C under dry Ar and treated
dropwise with a solution of butyllithium (0.56 mL, 2.6 M in
hexane, 1.5 mmol). After 60 min at -76 °C, gaseous CO2 was
bubbled through the mixture, and the temperature was
allowed to rise to 25 °C. After 12 h, volatiles were removed by
evaporation under reduced pressure, water was added to the
residue, and the pH was adjusted to 1 by acidification with 1
3,3,9,9-T e t r a k is [(3-c y a n o p h e n y l)m e t h y l]-2,4,8,10-
tetr a oxa sp ir o[5,5]u n d eca n e (12). The product obtained by
an analogous procedure using 3,3,9,9-tetrakis[(3-bromophe-
nyl)methyl]-2,4,8,10-tetraoxaspiro[5,5]undecane (11; 1.06 g;
1.27 mmol) was recrystallized from C2H5OH to give 3,3,9,9-
tetrakis[(3-cyanophenyl)methyl]-2,4,8,10-tetraoxaspiro[5,5]-
undecane (12; 0.550 g, 0.886 mmol, 70%) as a colorless solid:
J . Org. Chem, Vol. 68, No. 2, 2003 245

Sauriat-Dorizon et al.
M aqueous HCl. The aqueous phase was extracted with ether,
the combined extracts were dried over Na2SO4, and volatiles
were removed by evaporation under reduced pressure. The
residue was washed successively with hexane and toluene and
was then dried in vacuo to give tecton 15 (0.15 g, 0.23 mmol,
74%) as a colorless solid: IR (NaCl) 1694 cm-1;1H NMR (300
MHz, DMDO-d6) δ 12.8 (bs, 4H), 7.91 (d, 8H, 3J ) 8.4 Hz),
Full-matrix least-squares refinements on F2 led to final
residuals Rf ) 0.0836 and Rw ) 0.2426 for 6277 reflections
with I > 2σ(I).
Exch a n ge of Gu ests in Cr ysta ls of Tecton 1. Single
crystals of estimated composition 1‚10DMF‚xH2O and ap-
proximate dimensions 1 × 1 × 1 mm3 were grown in the
normal manner. The mother liquors were removed by pipet,
and the crystals were immediately rinsed several times with
CH3COOC2H5 and then kept in contact with CH3COOC2H5 at
25 °C for 12 h without stirring. The liquid was removed by
pipet, the recovered crystals were washed several times with
pentane and dried briefly in air, and their content was
determined by 1H NMR spectroscopy to be approximately 1‚
10CH3COOC2H5‚yH2O.12 The unit cell after exchange was
found to be orthorhombic with a ) 23.1030(12) Å, b ) 20.2381-
(11) Å, c ) 20.607(10) Å, and V ) 9635(14) Å3.
3
7.55 (d, 8H, J ) 8.4 Hz), 3.81 (s, 8H).
Cr ysta lliza tion of Tecton 1. Tecton 1 (2 mg) was dissolved
in DMF (1 mL) at 25 °C, toluene was added until a very slight
cloudiness was observed, and a small amount of DMF was
added to make the cloudiness disappear. Long colorless plates
crystallized as the mixture was allowed to stand undisturbed
for 12 h at 25 °C in a closed vial. Selected crystals were sealed
in capillaries with the mother liquors for study by X-ray
crystallography.
X-r a y Cr ysta llogr a p h ic Stu d y of Tecton 1. A full sphere
of data was collected at 220 K using a Bruker SMART 1000
CCD diffractometer with Mo KR radiation. Crystals of com-
pound 1 belong to the orthorhombic space group Pbcn with a
) 23.6973(17) Å, b ) 19.9952(15) Å, c ) 20.2313(15) Å, V )
9586.2(12) Å3, Dcalcd ) 1.287 g cm-3, and Z ) 4. The structure
was solved by direct methods using SHELXS-97 and refined
with SHELXL-97.22 An empirical correction (SADABS)23 was
applied to the data to account for absorption and other
geometry-dependent effects. All non-hydrogen atoms were
refined anisotropically, whereas hydrogen atoms were placed
in ideal positions and refined as riding atoms. The included
guests were found to be highly disordered and could not be
resolved. The SQUEEZE option of the PLATON program was
used to eliminate the contribution of the guests and to give
final models based only on the ordered part of the structures.17
Ack n ow led gm en t. We are grateful to the Natural
Sciences and Engineering Research Council of Canada,
the Ministe`re de l’EÄ ducation du Que´bec, and Merck
Frosst for financial support. In addition, acknowledg-
ment is made to the donors of the Petroleum Research
Fund, administered by the American Chemical Society,
for support of this research. We also thank Dr. Michel
Simard (De´partement de Chimie, Universite´ de Mont-
re´al) for helping us collect and analyze the crystal-
lographic data used to determine the structure of tecton
1.
Su p p or t in g In for m a t ion Ava ila b le: 1H and 13C NMR
spectra of compounds 8, 11, and 15; an ORTEP drawing; and
tables of crystallographic data, atomic coordinates, anisotropic
thermal parameters, and bond lengths and angles for tecton
1. This material is available free of charge via the Internet at
http://pubs.acs.org.
(22) Sheldrick, G. M. SHELXS-97, Program for the Solution of
Crystal Structures and SHELXL-97, Program for the Refinement of
Crystal Structures; Universita¨t Go¨ttingen: Go¨ttingen, Germany, 1997.
(23) Sheldrick, G. M. SADABS, Bruker Area Detector Absorption
Corrections; Bruker AXS Inc.: Madison, WI, 1996.
J O026267T
246 J . Org. Chem., Vol. 68, No. 2, 2003