J. Am. Chem. Soc. 1997, 119, 10245-10246
10245
Chart 1. An Illustration of a Two-Dimensional â-Network
Controlled Spacing of Metal Atoms via Ligand
Hydrogen Bonds
Formed from the Bipyridyl Urea, 1, and a Diacetylene
Dicarboxylic Acid or Diola
Caroline L. Schauer, Eric Matwey, Frank W. Fowler,* and
Joseph W. Lauher*
Department of Chemistry
State UniVersity of New York
Stony Brook, New York 11794
ReceiVed June 13, 1997
a The intermolecular spacing is determined by the urea-hydrogen
bonds.
The binary or host-guest approach is a powerful strategy
for supramolecular synthesis1,2 and crystal design. In the binary
approach, the functionalities required for supramolecular struc-
ture and function are distributed over two molecules. We
illustrated this convergent strategy by the design and preparation
of a series of binary cocrystals in which a urea or oxalamide
host determines the structure and spaces a diacetylene guest at
the distance required for a topochemical polymerization, the
desired function (Chart 1). The host-guest interaction is based
upon the strong pyridine-hydroxyl hydrogen bond. Pyridyl-
substituted ureas,4 such as 1, self-assemble into one-dimensional
R-networks3,4 with a repeat distance of about 4.6 Å, while
pyridyl-substituted oxalamides,5 such as 2, self-assemble at the
slightly longer distance of 5.1 Å. In the diacetylene binary
crystals, these intermolecular distances, characteristic of the host,
are imposed upon the diacetylene guests.
Chart 2. Proposed One-Dimensional R-Networks Formed
by the Bipyridyl Urea, 1, and the Bipyridyl Oxalamide, 2,
Each Bridging a Pair of Metal Ionsa
a The expected characteristic spacings shown are determined by the
dimensions of the hydrogen bond functionalities.
These pyridyl-derivatized ureas and oxalamides designed as
hosts for dicarboxylic acids and diols can also be used as ligand
hosts for the controlled spacing of metal atoms in a designed
crystal (Chart 2). We now wish to report the results of our
initial studies in which we explored the cocrystallization of
molecules6 1 and 2 with silver salts.7-9
ion, yielding a four-coordinate tetrahedral Ag+ cation with the
closest Ag+-Ag+ spacing equal to the 4.625(1) Å cell constant.
The resulting structure, Figure 1, consists of two-dimensional
layers held together by metal-ligand bonds. These layers are
aligned by the ligand-ligand hydrogen bonds. The BF4
counteranions sit in the aligned channels between the urea
ligands.
-
O
O
H
N
N
N
N
H
N
H
N
N
N
H
O
(7) Bipyridyl ligands have been used by many groups for metal based
supramolecular syntheses. Stang, P. J.; Persky, N. E.; Manna, J. J. Am.
Chem. Soc. 1997, 119, 4777-4778 and references therein, Robson, R.;
Abrahams, B. F.; Batten, S. R.; Gable, R. W.; Hoskins, B. F.; Liu, J.
Supramolecular Architecture; American Chemical Society: Washington,
DC, 1992; Chapter 19. Losier, P.; Zaworotko, M. J. Angew. Chem., Int.
Ed. Engl. 1996, 35, 2779-2782. Fujita, M.; Kwon, Y. J.; Washizu, S.;
Ogura, K. J. Am. Chem. Soc. 1994, 116, 1151-1152. Carlucci, L.; Ciani,
G.; Proserpio, D. M.; Sironi, A. J. Am. Chem. Soc. 1995, 117, 4562-4569.
Baxter, P. N. W.; Hanan, G. S.; Lehn, J.-M. Chem. Commun. 1996 2019-
2020. Baxter, P. N. W.; Lehn, J.-M.; Fischer, J.; Youinou, M.-T. Angew.
Chem., Int. Ed. Engl. 1994, 33, 2284-2289.
(8) Hydrogen bonds between coordinated ligands have been studied by
others. Schroder, G.; Lippert, B.; Sabat, M.; Lock, C. J. L.; Faggiani, R.;
Son, B.; Sigel, H. J. Chem Soc., Dalton Trans. 1995, 3767-3775. Burrows,
A. D.; Chan, C. W.; Chowdry, M. M.; McGrady, J. J.; Mingos, D. M. P.
Chem. Soc. ReV. 1995, 329-339. Munakata, M.; Wu, L. P.; Yamamoto,
M.; Kuroda-Sowa, T.; Mackawa, M. J. Am. Chem. Soc. 1996, 118, 3117-
3124.
(9) DNA based methods for spacing small gold particles have been
reported: Mirkin, C. A.; Letsinger, R. L.; Mucic, R. C.; Storhoff, J. J. Nature
1996, 382, 607-609. Alivisatos, A. P.; Johnsson, K. P.; Peng, X.; Wilson,
T. E.; Loweth, C. J.; Bruchez, M. P., Jr.; Schultz, P. G. Nature 1996, 382,
609-611.
(10) X-ray data for 3: C26H28AgBFN8O2; M ) 679.2; tetragonal; a )
11.984(2) Å, c ) 4.625(1) Å, V ) 664.2 Å3; Z ) 1; Fcalc ) 1.698; space
group P4 (No. 81); 1236 observations (I > 3σ); 124 variables; R ) 0.032,
Rw ) 0.039. 4 (X ) NO3-): C28H28AgN9O7; M ) 710.7; tetragonal; a )
16.869(2) Å, c ) 5.123(1) Å; V ) 1457.9 Å3; Z ) 2; Fcalc ) 1.683; space
group P4/n (No. 85); 923 observations (I > 3σ); 114 variables; R ) 0.032,
Rw ) 0.041. 4 (X ) BF4-): C28H28AgBF4N8O4; M ) 735.2; tetragonal; a
) 16.957(2) Å, c ) 5.129(1) Å; V ) 1475.1 Å3; Z ) 2; Fcalc ) 1.655,
space group P4/n (No. 85); 596 observations (I > 3σ); 96 variables; R )
0.068; Rw ) 0.072. All data were collected at room temperature on an Enraf-
Nonius CAD4 diffractometer with use of Mo radiation.
1
2
The addition of 2 equiv of ligand 1 to a solution of AgBF4
gave the corresponding 2:1 coordination polymer [Ag(L1)2)]-
BF4, 3. The structure10 consists of a one-dimensional R-network
of pyridine-substituted ureas with a repeat distance of 4.625(1)
Å, corresponding to the c axis of a tetragonal unit cell (Figure
1). The pyridine nitrogen atoms are each coordinated to a Ag+
(1) Kane, J. J.; Liao, R. F.; Lauher, J. W.; Fowler, F. W. J. Am. Chem.
Soc. 1995, 117, 12003-12004.
(2) Coe, S.; Kane, J. J.; Nguyen, T. L.; Toledo, L. M.; Wininger, E.;
Fowler, F. W.; Lauher, J. W. J. Am. Chem. Soc. 1997, 119, 86-93.
(3) Supramolecular assemblies can be divided into four groups depending
upon the degree of translation symmetry. Discrete assemblies lack translation
symmetry and are characterized by their point group symmetry. An
R-network has one degree of translational symmetry and is characterized
by its rod group symmetry. A â-network has two degrees of translational
symmetry and is characterized by its layer group symmetry. A γ-network
has three degrees of translational symmetry and is characterized by its space
group symmetry. See: Lauher, J. W.; Chang, Y. L.; Fowler, F. W. Mol.
Cryst. Liq. Cryst. 1992, 211, 99-109.
(4) Zhao, X.; Chang, Y.-L.; Fowler, F. W.; Lauher, J. W. J. Am. Chem.
Soc. 1990, 112, 6627-6634. Chang, Y. L.; West, M. A.; Fowler, F. W.;
Lauher, J. W. J. Am. Chem. Soc. 1993, 115, 5591-6000.
(5) We have prepared a variety of oxamide-based cocrystals analogous
to the urea cocrystals described in ref 1.
(6) Compounds 1 and 2 were synthesized by the direct stoichiometric
reaction of diphenyl carbonate or diethyl oxalate with 3-aminomethylpy-
ridine. The silver derivatives were prepared by cocrystallizing 2 mol of the
ligand with 1 mol of silver salt from water or methanol/water solutions.
Details are given in the Supporting Information.
S0002-7863(97)01953-7 CCC: $14.00 © 1997 American Chemical Society