Open Pentiptycene Networks Assembled through Charge-Assisted Hydrogen Bonds

Article abstract of DOI:10.1021/acs.cgd.9b00801

A series of hydrogen-bonded networks was prepared incorporating ditopic, tritopic, or tetratopic polyamidinium tectons and linear pentiptycene dicarboxylates. The ditopic amidinium forms a 1D hydrogen bonded chain when combined with the pentiptycene tecton, while the tritopic trigonal planar amidinium tecton forms a 2D honeycomb network. A tetratopic amidinium tecton forms a 3D diamondoid network, which is 32-fold interpenetrated, tied for the highest degree of interpenetration observed for a hydrogen bonded network. The bulky pentiptycene functionality prohibits the polymers from packing efficiently, leading to voids within each structure. These frameworks were envisaged as potential molecular motors, but unfortunately, a lack of stability to solvent removal precluded an investigation of these properties.

Full text of DOI:10.1021/acs.cgd.9b00801

Article
Cite This: Cryst. Growth Des. XXXX, XXX, XXX−XXX
pubs.acs.org/crystal
Open Pentiptycene Networks Assembled through Charge-Assisted
Hydrogen Bonds
Stephanie A. Boer, Pei-Xi Wang, Mark J. MacLachlan, and Nicholas G. White*,†
†
‡
‡
†
Research School of Chemistry, The Australian National University, Canberra, Australian Capital Territory 2601, Australia
‡
Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, British Columbia V6T 1Z1, Canada
*
S Supporting Information
ABSTRACT: A series of hydrogen-bonded networks was prepared
incorporating ditopic, tritopic, or tetratopic polyamidinium tectons and
linear pentiptycene dicarboxylates. The ditopic amidinium forms a 1D
hydrogen bonded chain when combined with the pentiptycene tecton,
while the tritopic trigonal planar amidinium tecton forms a 2D
honeycomb network. A tetratopic amidinium tecton forms a 3D
diamondoid network, which is 32-fold interpenetrated, tied for the
highest degree of interpenetration observed for a hydrogen bonded
network. The bulky pentiptycene functionality prohibits the polymers
from packing efficiently, leading to voids within each structure. These
frameworks were envisaged as potential molecular motors, but
unfortunately, a lack of stability to solvent removal precluded an investigation of these properties.
INTRODUCTION
■
Hydrogen-bonded organic frameworks (HOFs) are supra-
molecular materials constructed via intermolecular hydrogen
1
−3
bonding interactions.
Early HOFs were assembled through
hydrogen bonding between neutral self-complementary
4
,5
6,7
8
groups, such as carboxylic acid,
amide,
alcohol, or
9
diaminotriazine. Subsequently, HOFs made in this manner
have been used to prepare a range of materials including ones
1
−3,10−14
that show impressive stability and permanent porosity.
Charge-assisted hydrogen bonds have also been employed
and in theory this may lead to more robust materials because
of the additional electrostatic attraction between the
components. HOFs containing charge-assisted hydrogen
bonds have been synthesized by pairing positively charged
1
5,16
hydrogen bond donor groups, such as guanidinium,
amidinium,
56
Figure 1. Structure and approximate dimensions of 12− and diagram
1
7−21
22
23
or imidazolium, with a range of anions.
2
showing R (8) hydrogen bonding geometry often observed in
2
A key advantage of using cationic and anionic components is
that a node-and-linker methodology, similar to that used in
reticular MOF/COF chemistry, can be implemented. Ward’s
group has demonstrated that the guanidinium cation and
polysulfonate anions can be used to prepare a range of different
Building on this pioneering work, we
have used the interaction of amidinium and carboxylate tectons
to prepare open three-dimensional frameworks, and have
hydrogen-bonded amidinium/carboxylate frameworks.
2
4
geometry of pentiptycenes prevents them from packing
efficiently, and this property has been used to prepare porous
38−42
43−47
1
5,16,25−28
organic polymers,
and metal organic frameworks.
architectures.
Additionally, the groups of Yang and Garcia-Garibay have used
the pentiptycene group as the stator component in molecular
brakes and rotors, where the pentiptycene group remains
29,30
realized a range of diamondoid architectures,
as well as an
48−54
31
stationary while another part of the molecule moves.
open network with PtS topology. These networks are held
together by R (8) hydrogen bonding geometries (Figure 1),
2
2
32
In this work, we investigate whether the pentiptycene-
derived dicarboxylate anion 12 can be incorporated into
−
although other hydrogen bond geometries have also been
3
0,31,33−35
observed for amidinium···carboxylate interactions.
3
6,37
Pentiptycenes, part of the larger family of iptycenes,
are
Received: June 21, 2019
Revised: July 9, 2019
rigid molecules with phenyl rings attached to two [2.2.2]-
bicyclooctatriene bridgehead systems. The rigidity and
©
XXXX American Chemical Society
A
DOI: 10.1021/acs.cgd.9b00801
Cryst. Growth Des. XXXX, XXX, XXX−XXX

Crystal Growth & Design
Article
Scheme 1. Structure of Amidinium Tectons and Synthesis of New Trisamidinium, 3·3Cl
59
Figure 2. Solid state structure of 2·1. Water molecules and most hydrogen atoms omitted for clarity, PLATON-SQUEEZE was used.
2
+
3+
hydrogen-bonded framework materials. We are interested in
2 , a trigonal planar trisamidinium 3 , and two tetrahedral
tetraamidinium tectons, 44+ and 5 (Scheme 1). All
amidinium tectons were prepared as their chloride salts: 2·
4+
this for two reasons: first, to test the limits of the amidinium/
2−
carboxylate motif for self−assembly. The dianion 1 is large
O···O length ∼21 Å) and sterically demanding and as such
would be expected to be difficult to incorporate into a
57
29
30
(
2
Cl, 4·4Cl, and 5·4Cl were prepared following literature
58
procedures, 3·3Cl was prepared from the trisnitrile 6 in 89%
yield using LiHMDS followed by workup with ethanolic HCl.
Preparation of Frameworks. Frameworks were prepared as
single crystals by simply layering solutions of each tecton in
water/alcohol mixtures. Frameworks were characterized by
single crystal X-ray diffraction (SCXRD) and powder X-ray
diffraction (PXRD) studies, as well as NMR and IR
spectroscopy, thermogravimetric analysis (TGA) and elemen-
tal analysis (see Experimental Section and Supporting
Information).
55
framework held together by hydrogen bonds. Second, if such
a framework could be prepared, it may be possible that it
would act as a molecular rotor where the entire pentiptycene
group acted as the rotor (in contrast to previous pentiptycene-
based rotors where the pentiptycene acted as the stator).
RESULTS AND DISCUSSION
■
Synthesis. Synthesis of Pentiptycene Dicarboxylate. We
have optimized the synthesis of the previously reported
2
H
44
dicarboxylic acid 1 , resulting in its synthesis in 44% overall
yield from anthracene. An optimized route to gram quantities
of this material is provided in the Supporting Information.
Addition of n-tetrabutylammonium (TBA) hydroxide to the
SCXRD Studies. 2·1. We first investigated the ability of the
2−
pentiptycene dicarboxylate 1 to form hydrogen bonded
networks with the linear bisamidinium 2 . Layering solutions
of TBA ·1 with 2·2Cl gave colorless crystals, which SCXRD
revealed to be a 1D hydrogen bonded chain, 2·1 (Figure 2).
The asymmetric unit contains half a molecule of each tecton
and one water molecule, as well as a small region of electron
density, which appeared to correspond to a disordered solvent
molecule. This could not be modeled sensibly and so
2+
2
H
2
diacid 1 gave TBA ·1, which shows good solubility in water
2
and in a range of organic solvents. We also prepared a new
extended pentiptycene diacid S12H containing two extra phenyl
rings but were unable to isolate any crystalline hydrogen
bonded materials from this material, in part due to its low
solubility (see Supporting Information).
59
Synthesis of Amidinium Tectons. In this work, we study
PLATON-SQUEEZE was used to include the electron
density in the model.
the crystallization of 12 with the linear bisamidinium tecton
−
B
DOI: 10.1021/acs.cgd.9b00801
Cryst. Growth Des. XXXX, XXX, XXX−XXX

Crystal Growth & Design
Article
Figure 3. Views of the solid state structure of 3 ·1 : (a) a single hexagon and (b) two of the seven interpenetrating 2D honeycomb networks. Most
2
3
59
hydrogen atoms omitted for clarity, PLATON-SQUEEZE used.
Figure 4. Diagram showing the 1D H-bonded chains in the solid state structure of 4·1 . (a) View showing hydrogen bonding arrangement: circled
2
sites indicate that no amidinium···carboxylate hydrogen bonds are present, limiting the dimensionality of the network; arrows indicate the direction
of the 1D hydrogen bonded chain. (b) View of the 1D H-bonded chain (indicated with a dotted blue line). Disorder and most hydrogens omitted
59
for clarity, PLATON-SQUEEZE used.
The amidinium and carboxylate groups are involved in
R (8) hydrogen bonding, although there is some distortion
2
close together, and leads to solvent-filled channels in the
framework (Figure S29).
2
from a completely linear H-bond. The water molecule
hydrogen bonds to amidinium and carboxylate groups of the
4·1 . We next attempted to prepare 3D frameworks from
2
4+
4+
the tetrahedral amidinium tectons, 4 and 5 . Crystals of 4·12
were analyzed by SCXRD, revealing that the network
crystallized with one tetraamidinium and two dicarboxylate
molecules in the asymmetric unit.
1
D H-bonded chain and the pentiptycene motifs interdigitate,
presumably to maximize close-packing.
2
−
32
·1 . Having demonstrated that 1 could be used to form
3
1
D H-bonded chains, we next attempted to increase the
Of the four crystallographically distinct carboxylate and
dimensionality of the network by employing the trigonal
amidinium groups present, three of each are involved in end-
3+
2
amidinium tecton 3 . The resulting crystals of 3 ·1 rapidly
to-end R (8) hydrogen bonding. Two of these interactions link
2
3
2
lost crystallinity upon removal from solvent, and despite
growing very large crystals and employing synchrotron
radiation, high quality data could not be obtained. However,
sufficient data were obtained to determine the connectivity of
the structure (Figure 3).
the structure into 1D H-bonded chains (Figure 4). The third
2
2
R (8) interaction is between an amidinium group and one end
of a dicarboxylate anion; the other end of this anion does not
H-bond to an amidinium group. This leaves one amidinium
and one carboxylate group “free”; these groups presumably H-
bond to solvent molecules, although these could not be located
crystallographically, and were accounted for using PLATON-
All of the amidinium and carboxylate groups are involved in
R (8) hydrogen bonding, giving a hexagonal (6,3) sheet
2
2
59
structure. The 2D sheets are 7-fold 2D → 2D parallel
interpenetrated and the interpenetrated 2D sheets are stacked,
producing significant void volume between the sheets,
accounting for 59% of the unit cell volume (electron density
within the voids could not be modeled and so was processed
SQUEEZE. These 1D chains interweave through lateral
amidinium···carboxylate H-bonds to give a 3D lattice (Figure
S30). Despite the low dimensionality of the network the
material contains solvent-accessible 1D channels that account
for 44% of the unit cell volume.
59
with PLATON-SQUEEZE ). It appears that the pentiptycene
motif prevents the interpenetrating 2D sheets from stacking
5·1 . The pentiptycene dicarboxylate was also crystallized
2
4+
with the larger tetraamidinium tecton, 5 , forming framework
C
DOI: 10.1021/acs.cgd.9b00801
Cryst. Growth Des. XXXX, XXX, XXX−XXX

Crystal Growth & Design
Article
Figure 5. Views of the solid state structure of 5·1 : (a) view of the hydrogen bonding arrangement and (b) view of packing. Most hydrogen atoms
2
5
9
omitted for clarity, PLATON-SQUEEZE used.
2
−
5
·1 . The asymmetric unit contains one-half of a tecton of 1
the frameworks by solvent exchange with ethanol and then
2
4+
2
and one-quarter of a tecton of 5 , which participate in R (8)
used supercritical CO drying to remove any solvent. Using
2
2
hydrogen bonding arrangement giving a 3D diamondoid
network (Figure 5). Because of the long tectons employed in
this procedure, we saw that the frameworks retained some
degree of crystallinity upon activation and drying (see Figures
S13 and S14). However, given that there was a substantial loss
of crystallinity, it was felt that SS-NMR experiments of
dynamics would not give useful data owing to a variety of
environments in the crystalline and amorphous components.
5
·1 , the structure is 32-fold interpenetrated (Figure S33).
2
Despite the interpenetration, the framework still contains
solvent channels, accounting for 37% of the unit cell volume.
Discussion of SCXRD Structures. In this work, we have
prepared 1D, 2D, and 3D hydrogen-bonded networks from
Gas adsorption measurements indicated that both 4·1 and 5·
2
2
−
1 were nonporous, which we attribute to the collapse of the
1
. Interestingly, the only structure that does not form the
2
framework.
desired self-assembled framework is the 3D material 4·1 . This
2
is in contrast to previous results where a porphyrin-containing
tetracarboxylate did not form 2D networks but did form 3D
networks, which was attributed to the lower solubility of the
CONCLUSIONS
■
To test the limits of amidinium···carboxylate supramolecular
31
3
D material driving crystallization. In the current case, it is
framework formation, we incorporated the large pentiptycene
not clear why 4·1 does not form a network, but is presumably
2−
2
dicarboxylate 1 into hydrogen bonded networks. Despite the
related to the product having a lower solubility or forming
more readily than the desired diamondoid network.
large and bulky nature of this anion, we were able to prepare
1
D, 2D, and 3D frameworks. Products included an inter-
penetrated honeycomb network and a 32-fold interpenetrated
D diamondoid network, which we believe is tied for the
The structure of 5·1 contains 32 interpenetrating nets, and
2
yet remarkably still contains significant channels (37% of the
3
unit cell volume is void space, accounted for using PLATON-
highest degree of interpenetration observed in a hydrogen-
bonded material. Generally, even the low dimensional
materials we prepared were found to contain significant
solvent-filled voids, which appears to result from pentipty-
cene’s poor packing efficiency. While the 3D networks were
partially stable to evacuation, they did not show any nitrogen
absorption. Work directed at preparing more robust supra-
molecular materials is underway.
5
9
SQUEEZE ). To the best of our knowledge, this is the equal-
most interpenetrated H-bonded network reported to date. The
other 32-fold interpenetrated H-bonded network also contains
4
+
5
as the cation, with these cations linked by 4,4′-
30
biphenyldicarboxylate anions. Interestingly, the anion in 5·
12 is significantly longer than biphenyldicarboxylate, yet it leads
to the same degree of interpenetration, possibly due to the
steric demands of the pentiptycene group.
Generally the structures all contain significant amounts of
void space, which we attribute to the difficulty in pentiptycene
molecules packing efficiently. The 1D hydrogen bonded chain,
EXPERIMENTAL SECTION
Synthesis. General Remarks. The pentiptycene diacid 1 was
■
2H
39,60
prepared from diethynylpentiptycene
by modification of the
4
4
2
·1, contains the least solvent, and it appears that pentiptycene
previously reported procedure; an optimized route to this
compound is provided in the Supporting Information. The amidinium
units can pack relatively efficiently when they are all facing in
57
29
30
58
the same direction (as they do in this structure). However,
tectons 2·2Cl, 4·4Cl, and 5·4Cl, and the trisnitrile 6 were
prepared as previously described. Yields of frameworks (mmol and%)
were calculated accounting for the % solvent indicated by TGA. In all
3+
4+
4+
when nonlinear tectons, such as 3 , 4 , or 5 are used, the
amidinium···carboxylate interactions force the pentiptycenes
out of alignment, resulting in poor packing efficiency.
cases, where NMR spectroscopy was conducted in d -DMSO
6
containing DCl(aq), the integration of the amidinium N−H proton
resonances was lower than expected because of H/D exchangethe
idealized integration values are provided in the listing of NMR data.
Details of instrumentation and characterization are provided in the
Supporting Information.
Evacuation of Frameworks. To see whether the networks
exhibited molecular rotor properties, we attempted to prepare
evacuated samples of 4·1 and 5·1 to allow a solid-state NMR
2
2
(
SS-NMR) study of any molecular rotation. We first activated
D
DOI: 10.1021/acs.cgd.9b00801
Cryst. Growth Des. XXXX, XXX, XXX−XXX

Crystal Growth & Design
Article
2
H
TBA ·1. 1 (0.431 g, 0.600 mmol) was suspended in ethanol (10
C 73.9, H 4.1, N 4.6; calcd for 4·1 ·13H O (C133H114N O ): C 73.9,
2
2
2
8
21
mL), and TBA·OH in methanol (1.0 M, 1.2 mL, 1.2 mmol) was
added, causing the solid to dissolve. The solvent was removed under
vacuum to give the product as an off-white powder. Yield: 0.720 g
H 5.3. N 5.2%.·
5·1 . The tetraamidinium 5·4Cl (7.5 mg, 16 μmol) was dissolved
2
in water (2 mL) and carefully layered with a buffer layer of methanol
(
0.60 mmol, 100%).
(5 mL) and, then, i-propanol (2 mL), followed by a solution of TBA ·
2
1
H NMR (d -DMSO): 8.01 (d, J = 7.8 Hz, 4H), 7.88 (d, J = 7.8
1 (10 mg, 8.0 μmol) in i-propanol (2 mL). The solution was left to
stand for 7 days, during which time colorless needle crystals were
formed. These crystals were recovered by filtration and air-dried to
6
Hz, 4H), 7.52 (d, J = 8.6 Hz, 8H), 6.98 (d, J = 8.6 Hz, 8H), 6.00 (s,
4
1
1
8
H), 3.04−3.21 (m, 16H), 1.50−1.65 (m, 16H), 1.25−1.38 (m,
6H), 0.93 (t, J = 7.3 Hz, 24H) ppm. C NMR (d -DMSO): 167.6,
1
3
give 5·1
. Yield: 4.7 mg (1.9 μmol, 11%).
6
2
1
44.9, 144.3, 143.7, 131.4, 129.7, 125.8, 124.4, 121.8, 114.5, 98.9,
4.1, 58.0, 51.8, 23.5, 19.7, 14.0 ppm. ESI-MS (neg): 358.2., calcd for
H NMR [d -DMSO containing 1 drop DCl(aq)]: 9.48 (br. s., 8H),
6
9.22 (br. s., 8H), 8.13−8.19 (m, 16H), 7.96 (s, 16H), 7.84 (d, J = 8.7
Hz, 8H), 7.47−7.56 (m, 24H), 6.98−7.02 (m, 16H), 6.03(s, 8H)
2
−
[
[
(
C H O ]
= 358.1 Da. ESI-MS (pos): 242.3, calcd for
5
2
28
4
+
−1
−1
C H N] = 242.3 Da. ATR-IR (inter alia): 1602, 1545 cm
ppm. ATR-IR (inter alia): 1673, 1602, 1579, 1537 cm (CN, C
16
36
CO stretches). M. Pt.: > 260 °C.
O stretches). EA: C 75.9, H 4.4, N 4.3; calcd for 5·1 ·14H O
2 2
3
·3Cl. A solution of 6 (0.191 g, 0.500 mmol) in THF (2 mL) was
(C157
H
132
N
8
O
22): C 76.0, H 5.4, N 4.5%.
cooled to 0 °C under a nitrogen atmosphere, and a solution of
LiHMDS in THF (1.0 M 3.0 mL, 3.0 mmol) was added dropwise.
The solution was allowed to warm to room temperature and stirred
overnight. The solution was cooled to 0 °C and ethanolic HCl
We repeated the synthesis of 5·1 several times but were never able to
2
obtain large quantities of crystalline material. Mixing the solutions of 5·
4Cl and TBA
noncrystalline.
·1 more rapidly gave larger yields of product, but this was
2
(
prepared by the cautious addition of 0.5 mL of acetyl chloride to 4.5
X-ray Crystallography. Crystals of 3
2
·1 , 4·1 , and 5·1 were
3
2
2
mL of ethanol at 0 °C) was added dropwise, causing the formation of
a pale precipitate. The precipitate was isolated by filtration and
washed with ethanol (2 × 5 mL) and THF (2 × 3 mL). It was
suspended in ethanol (20 mL) and sonicated for 1 h, and the resulting
pale solid isolated by filtration and washed with ethanol (2 × 3 mL)
and THF (2 × 3 mL). Drying in vacuo gave 3·3Cl as a white powder.
either very small or lost solvent rapidly. The crystallography for these
structures was difficult and required the use of synchrotron radiation.
Data for these compounds are of relatively low quality, but the overall
connectivity can be determined unambiguously. A brief description of
the crystallography is given below, with further details provided in the
Supporting Information.
Yield: 0.241 g (0.444 mmol, 89%).
Data for 2·1 were collected mirror-monochromated Cu Kα
radiation on an Agilent SuperNova diffractometer. Crystals were
cooled to 150 K using a Cryostream N2 open-flow cooling device.
Raw data (including data reduction, interframe scaling, unit cell
1
H NMR (d -DMSO): 9.57 (br. s., 6H), 9.34 (br. s., 6H), 8.24 (d, J
6
1
3
=
8.2 Hz, 6H), 8.19 (s, 3H), 8.05 (d, J = 8.2 Hz, 6H) ppm. C NMR
(d -DMSO): 165.1, 144.6, 140.2, 128.7, 127.8, 127.2, 126.1 ppm.
6
61
+
+
HRESI-MS: 433.2126, calc. for [C H N ] (i.e., loss of 2H and
refinement and corrections) were processed using CrysAlisPro. Data
for 3 were collected on the MX1 beamline at the
2
7
25
6
−
−1
3
Cl ): 433.2135 Da. ATR-IR (inter alia): 1694, 1670, 1541 cm
·1 , 4·1 , and 5·1
2 3 2 2
62
(
CN, CO stretches). M. Pt.: > 260 °C.
Australian Synchrotron. Crystals were cooled to 100 K using a
2
·1. The bisamidinium 2·2Cl (3.5 mg, 15 μmol) was dissolved in
Cryostream N2 open-flow cooling device. Data indexing and
63
water (5 mL) and the clear solution frozen. The frozen solution was
carefully layered with ethanol (2 mL) and then a solution of the
integration was conducted using the XDS package.
The structures of 2·1 and 5·1 were solved with SUPERFLIP and
refined using full-matrix least-squares on F within the CRYSTALS
64
2
2
TBA ·1 (18 mg, 15 μmol) in ethanol (3 mL). This was allowed to
2
6
5
suite. The structures of 3 ·1 and 4·12 were solved by direct
stand at room temperature over the weekend resulting in the
formation of a white crystalline solid. This was isolated by filtration,
washed with ethanol (3 × 1 mL), and dried thoroughly. Yield: 7.5 mg
2
3
methods using SHELXS and refined using least-squares methods with
SHELXL within OLEX2.
66
(
8.5 μmol, 57%).
1
H NMR [d -DMSO containing a drop of conc. DCl(aq)]: 9.75 (br.
6
ASSOCIATED CONTENT
Supporting Information
■
s, 4H), 9.44 (br. s, 4H), 8.10−8.15 (m, 8H), 8.03 (s, 4H), 7.47−7.51
m, 8H), 6.94−6.97 (m, 8H), 5.99 (s, 4H) ppm. IR (ATR) (inter
*
S
(
−
1
alia): 1689, 1597, 1532 cm (CN, CO stretches). EA: C 78.4, H
The Supporting Information is available free of charge on the
ACS Publications website at DOI: 10.1021/acs.cgd.9b00801.
4
.7, N 5.9; calcd for 2·1·2H O (C H N O ): C 78.6, H 4.8, N 6.1%.
2
60 44
4
6
3
·1 . The trisamidinium 3·3Cl (3.0 mg, 5.0 μmol) was dissolved
3
2
Characterization details, NMR spectra of new com-
in water (3 mL) and carefully layered with a buffer layer of ethanol
2
H
(
(
10 mL) then methanol (2 mL), followed by a solution of TBA ·1
pounds, optimized synthetic procedure for 1 , synthesis
2
2
H
10 mg, 8.3 μmol) in methanol (1 mL). The solution was left to stand
of extended pentiptycene diacid S1 , crystallographic
for 7 days, during which time long colorless needle crystals were
formed. These crystals were recovered by filtration and air-dried to
give 3 ·1 . Yield: 4.4 mg (1.3 μmol, 52%).
details. and additional crystallographic figures (PDF)
2
3
Accession Codes
1
H NMR [d -DMSO containing 1 drop DCl(aq)]: 9.63 (br. s., 12H),
6
CCDC 1917068−1917071 contain the supplementary crys-
tallographic data for this paper. These data can be obtained
free of charge via www.ccdc.cam.ac.uk/data_request/cif, or by
emailing data_request@ccdc.cam.ac.uk, or by contacting The
Cambridge Crystallographic Data Centre, 12 Union Road,
Cambridge CB2 1EZ, UK; fax: +44 1223 336033.
9
8
6
.35 (br. s., 12H), 8.20 (d, J = 8.2 Hz, 12H), 8.08−8.17 (m, 30H),
.03 (d, J = 8.2 Hz, 12H), 7.48−7.52 (m, 24H), 6.94−6.99 (m, 24H),
−
1
.00 (s, 12H) ppm. ATR-IR (inter alia): 1673, 1580, 1533 cm (C
N, CO stretches). EA: C 76.1, H 4.6, N 5.1; calcd for 3 ·1 ·16H O
2
3
2
(
C H N O ): C 76.2, H 5.2, N 5.1%.
210 170 12 28
4
·1 . The tetraamidinium 4·4Cl (10 mg, 6.2 μmol) was dissolved
2
in water (1 mL) and carefully layered with a buffer layer of methanol
(
(
9 mL) and then ethanol (1 mL), followed by a solution of TBA ·1
2
AUTHOR INFORMATION
■
10 mg, 12 μmol) in a 1:1 mixture of i-propanol/ethanol (1 mL). The
Corresponding Author
*E-mail: nicholas.white@anu.edu.au. URL: www.nwhitegroup.
com.
solution was left to stand for 12 days, during which time long colorless
needle crystals were formed. These crystals were recovered by
filtration and air-dried to give 4·1 . Yield: 7.0 mg (3.1 μmol, 50%).
2
1
H NMR [d -DMSO containing 1 drop DCl(aq)]: 9.59 (s. br., 8H),
6
ORCID
9
7
.32 (s. br., 8H), 8.11−8.17 (m, 16H), 7.92 (d, J = 8.3 Hz, 8H),
.47−7.55 (m, 24 H), 6.95−6.99 (m, 16H), 6.03 (s, 8H) ppm. ATR-
Mark J. MacLachlan: 0000-0002-3546-7132
Nicholas G. White: 0000-0003-2975-0887
−
1
IR (inter alia): 1666, 1601, 1582 cm (CN, CO stretches). EA:
E
DOI: 10.1021/acs.cgd.9b00801
Cryst. Growth Des. XXXX, XXX, XXX−XXX

Crystal Growth & Design
Article
Notes
synthesis: prediction and synthesis of self-assembled infinite rods. J.
Chem. Soc., Chem. Commun. 1994, 2135−6.
The authors declare no competing financial interest.
(
18) Felix, O.; Hosseini, M. W.; De Cian, A.; Fischer, J. The
́
Simultaneous Use of H-Bonding and Coulomb Interactions for the
Self-Assembly of Fumaric Acid and Cyclic Bisamidine into One- and
Two-Dimensional Molecular Networks. Angew. Chem., Int. Ed. Engl.
ACKNOWLEDGMENTS
■
We thank the Australian Research Council for funding this
work (DE170100200 to N.G.W.). Part of this research was
undertaken on the MX1 beamline at the Australian
Synchrotron, part of ANSTO. M.J.M. thanks NSERC
1
997, 36, 102−104.
6
2
(19) Lie, S.; Maris, T.; Malveau, C.; Beaudoin, D.; Helzy, F.; Wuest,
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Bonding in Carboxylate Salts of a Bis(amidine). Cryst. Growth Des.
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Discovery Grant) for support.
2
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20) Lie, S.; Maris, T.; Wuest, J. D. Molecular Networks Created by
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Cryst. Growth Des. XXXX, XXX, XXX−XXX