One-dimensional supramolecular tapes in the co-crystals of 2,5-dibromo-3,6-dihydroxy-1,4- benzoquinone (bromanilic acid) with heterocyclic compounds containing a pyrazine ring unit through hydrogen bonding, and the segregated stacks of eachmolecule are formed. Fig. 1, 2 and 3 show the structures of the one-dimensional tapes in 5, 6 and 7 with geometrical parameters for the tapes, respectively. Table 1 Crystal data and details of measurementsa for co-crystals 5, 6 and 7b Property 5 6 7C10H6Br2N2O4 377.99 Monoclinic C14H8Br2N2O4 428.04 Monoclinic C18H10Br2N2O4 478.1 Monoclinic P21/n P21/m C2/m Formula MCrystal system Space group a/Å b/Å c/Å /° V/Å3 ZT/K 5.721 (Mo- 12.419(7) 7.951(2) 8.502(1) 3.9288(4) 22.853(4) 6.890(2) 17.469(5) 3.913(1) 10.858(2) 107.87(4) 90.69(2) 100.80(1) 811.2(5) 711.0(3) 624.8(2) 2 2 2 296(2) 296(2) 296(2) 5.025 6.494 1729 1782 1481 623 1674 1389 0.0743 0.0556 0.0308 0.1828 0.1384 0.0742 .PP–1 Measured reflections Unique reflections R1 [F, I > 2 (I)] wR2 [F2, I > 2 (I)] a The data for 5 and 7 were measured on a Rigaku R-AXIS IV imaging plate area detector using 0R. UDGLDWLRQ = 0.71070 Å). An absorption correction was not applied. The data for 6 were collected on a Rigaku AFC-7R diffractometer using 0R. UDGLDWLRQ = 0.71070 Å). Absorption correction was applied using empirical procedures based on azimuthal scans of three reflections having an Eulerian angle, , near 90°. b All structures were solved by direct methods and refined by full-matrix least-squares on F2 with SHELX97.19All nonhydrogen atoms were refined anisotropically.Hydrogen atoms of 5 and 6 were localized in the Fourier maps and refined isotropically. Hydrogen atoms of 7 were placed geometrically and refined by using a riding model. Click here for full crystallographic data (CCDC no. 1350/23). Masaaki Tomura* and Yoshiro Yamashita† Institute for Molecular Science, Modaiji, Okazaki 444-8585, Japan. E-mail: tomura@ims.ac.jp Received 22nd May 2000, Accepted 12th June 2000, Published 15th June 2000 Supramolecular synthons formed with 2,5-dibromo-3,6-dihydroxy-1,4-benzoquinone (bromanilic acid) and heterocyclic aromatic compounds, phenazine, quinoxaline and pyrazine were successfully used in the design of robust one-dimensional supramolecular tapes.The design of new molecular architectures for crystal engineering has generated great interest in recent years.1–4 In particular, supramolecular patterns based on the tapes, ribbons and sheets, which are formed with hydrogen bonding, are very important for crystal engineering and materials science.5 For the purpose of designing crystal structures and controlling molecular aggregations, Desiraju has proposed the term supramolecular synthons, which act as "building blocks" in crystal engineering.6 A large number of the synthons identified so far involve directional intermolecular interactions such as hydrogen bonding, C– H···O,7&±+��� 8 N···Cl9 and S···N10 interactions. We have recently reported the novel supramolecular synthon formed with 2,5-dichloro-3,6-dihydroxy-1,4-benzoquinone (chloranilic acid) and 4,4'-bipyridine11 or dipyridylacetylenes,12 and have shown the utility of this robust and reproducible synthon for constructing onedimensional supramolecular tapes.Moreover, benzoquinone derivatives with two hydroxy groups show both electron accepting and proton donating properties and undergo multistage protonation and deprotonation processes.13 Our ultimate goal is to control electron transfer between donor and acceptor molecules14 in a crystal through thermodynamic transformation15 of hydrogen bonds. With this in mind we have now carried out co-crystallization of 2,5-dibromo-3,6-dihydroxy-1,4-benzoquinone 1 (bromanilic acid) with heterocyclic aromatic compounds phenazine 2,16 quinoxaline 3 and pyrazine 4.We report here the crystal structures involving the one-dimensional tape patterns of the three co-crystals. The 1 : 1 co-crystals 5, 6 and 7 were isolated from an acetonitrile solution of 1 with 2, 3 and 4, respectively. Single crystals suitable for X-ray analysis were grown at room temperature by a diffusion method using an H-tube. The X-ray crystallographic analyses for 5, 6 and 7 were carried out, and the crystal data and details of measurements are summarized in Table 1. Co-crystals 5, 6 and 7 basically have the same structural pattern, that is, the one-dimensional supramolecular tapes are generated via the self-assembly of two molecules DOI: 10.1039/b004088f CrystEngComm, 2000, 16Fig.1 One-dimensional tape in co-crystal 5. Hydrogen bonding parameters are (in Å): Na–Ha 2.04, Na–Oa 2.75, Na–Ob 3.43, Ob–Hb 2.51, Ob–Ca 3.33. The dihedral angle between the least-squares planes for 1 and 2 is 43.9°. Fig. 2 One-dimensional tape in co-crystal 6. Hydrogen bonding parameters are (in Å): Na–Ha 2.05, Na–Oa 2.70, Na–Ob 2.98, Ob–Hb 2.80, Ob–Ca 3.14. The dihedral angle between the least-squares planes for 1 and 3 is 49.7°. Fig. 3 One-dimensional tape in co-crystal 7. Hydrogen bonding parameters are (in Å): Na–Ha 1.96, Na–Oa 2.69, Na–Ob 3.09. The dihedral angle between the least-squares planes for 1 and 4 is 90°. A significant difference in the distances of the O–H···N hydrogen bonds of the one-dimensional tapes is not observed, while the dihedral angle between the leastsquares planes for 1 and 4 in co-crystal 7 differs considerably from those for others.The planes for 1 and 4 lie on the mirror plane and are perpendicular to each other. In the case of the tapes in 5 and 6, the C–H···O interactions7,16 are found between the carbonyl groups of 1 and the aromatic hydrogens in the benzo parts of 2 and 3. The C–H···O interactions may reduce the dihedral angle within the tape structure. The symmetry of the heterocyclic compounds also affects the structure of the tapes. Only 3 is not symmetrical about the N–N axis in the molecule. Thus, the tape formed from 1 and 3 in co-crystal 6 does not have a straight structure but a zigzag one.For the co-crystals 5, 6 and 7, no proton transfer from 1 to the nitrogen atoms of heterocyclic compounds is observed.‡ The crystal structures of 5, 6 and 7 are shown in Fig. 4, 5 and 6, respectively. The segregated unistacks of each molecule are observed in the co-crystals 5 and 6. This packing motif is essentially the same as those previously obtained from the co-crystals of chloranilic acid with 1,2-bis(2-pyridyl)ethylene11 or 2,2'- dipyridylacetylene.12 This fact suggests that there is a "structure-preserving" ability of the supramolecular synthon formed from anilic acids. Moreover, this type of segregated columnar structure is very important for organic conducting materials such as the tetrathiafulvalene–tetracyanoquinodimethane (TTF– TCNQ) charge transfer complex.17 The interstack distances are 3.45 Å for 1 and 2 in 5, and 3.42 and 3.64 Å for 1 and 3 in 6, respectively.In the co-crystals 5 and 6, the intertape Br···Br contacts18 are also observed (3.59 Å for 5, 3.73 Å for 6) to be shorter than the sum of the van der Waals radii (3.90 Å). The co-crystal 7 crystallizes in the monoclinic space group C2/m. Each molecule 1 and 4 is stacked in a two-dimensional fashion and forms layers which are perpendicular to each other (Fig. 6). Within the layers, the minimum distances between the least-squares planes for the molecules are 3.45 and 4.08 Å for 1 and 4, respectively.Fig. 4 Crystal structure of 5 viewed along the b axis.Fig. 5 Crystal structure of 6 viewed along the c axis. Fig. 6 Crystal structure of 7 viewed along the b axis. The above results suggest that the supramolecular synthon formed with anilic acids and heterocyclic compounds can yield the robust one-dimensional supramolecular tapes and realize preserved interesting crystal structures. Studies on the characterizatiohysical properties of the co-crystals 5, 6 and 7 and the construction of new molecular architectures using the supramolecular synthon described here are now in progress. Acknowledgements This work was supported by a Grant-in-Aid for Scientific Research on Priority Areas from the Ministry of Education, Science, Sports and Culture, Japan. References 1 G. M. J. Schmidt, Pure Appl.Chem., 1971, 27, 647. 2 G. R. Desiraju, Crystal Engineering: The Design of Organic Solids, Elsevier, Amsterdam, 1989. 3 W. Jones, Organic Molecular Solids: Properties and Applications, CRC Press, New York, 1997. 4 Crystal Engineering: From Molecules and Crystals to Materials, ed. D. Braga, F. Grepioni and A. G. Orpen, Kluwer Academic Publishers, Dordrecht, 1999. 5 R. E. Meléndez and A. D. Hamilton, in Design of Organic Solids, ed. E. Weber, Springer-Verlag, Berlin, 1998, p. 97. 6 G. R. Desiraju, Angew. Chem., Int. Ed. Engl., 1995, 34, 2311. 7 (a) R. Taylor and O. Kennard, J. Am. Chem. Soc., 1982, 104, 5063; (b) K. Biradha, C. V. K. Sharma, K. Panneerselvam, L. Shimoni, H. L. Carrell, D. E. Zacharias and G. R. Desiraju, J.Chem. Soc., Chem. Commun., 1993, 1473. 8 M. Nishio, Y. Umezawa, M. Hirota and Y. Takeuchi, Tetrahedron, 1995, 51, 8665. 9 (a) D. S. Reddy, K. Panneerselvam, T. Pilati and G. R. Desiraju, J. Chem. Soc., Chem. Commun., 1993, 661; (b) D. S. Reddy, B. S. Goud, K. Panneerselvam and G. R. Desiraju, J. Chem. Soc., Chem. Commun., 1993, 663. 10 (a) C. Kabuto, T. Suzuki, Y. Yamashita and T. Mukai, Chem. Lett., 1986, 1433; (b) M. Tomura and Y. Yamashita, Synth. Met., 1997, 86, 1871; (c) Y. Yamashita, K. Ono, M. Tomura and K. Imaeda, Chem. Commun., 1997, 1851; (d) Y. Yamashita, K. Ono, M. Tomura and S. Tanaka, Tetrahedron, 1997, 53, 10169. 11 M. B. Zaman, M. Tomura and Y. Yamashita, Chem. Commun., 1999, 999. 12 M. B. Zaman, M. Tomura and Y. Yamashita, Org.Lett., 2000, 2, 273. 13 (a) E. K. Andersen, Acta Crystallogr., 1967, 22, 188; (b) M. B. Zaman, Y. Morita, J. Toyoda, H. Yamochi, G. Saito, N. Yoneyama, T. Enoki and K. Nakasuji, Chem. Lett., 1997, 729. 14 M. L. Greer, B. J. McGee, R. D. Rogers and S. C. Blackstock, Angew. Chem., Int. Ed. Engl., 1997, 36, 1864. 15 (a) S. R. Byrn, D. Y. Curtin and I. C. Paul, J. Am. Chem. Soc., 1972, 94, 890; (b) A. Katrusiak, Acta Crystallogr., Sect. B, 1991, 47, 398; (c) M. T. Reetz, S. Höger and K. Harms, Angew. Chem., Int. Ed. Engl., 1994, 33, 181. 16 E. Batchelor, J. Klinowski and W. Jones, J. Mater. Chem., 2000, 10, 839. 17 (a) J. P. Ferraris, D. O. Cowan, V. Walatka, Jr. and J. H. Perlstein, J. Am. Chem. Soc., 1973, 95, 948; (b) T. E. Phillips, T. J. Kistenmacher, J. P. Ferraris and D. O. Cowan, J. Chem. Soc., Chem. Commun., 1973, 471. 18 D. S. Reddy, D. C. Craig and G. R. Desiraju, J. Chem. Soc., Chem. Commun., 1994, 1457. 19 G. M. Sheldrick, SHELX97, Program for the structure solution and refinement of crystal structures, 1997, University of Göttingen, Germany.20 M. W. Schmidt, K. K. Baldridge, J. A. Boatz, S. T. Elbert, M. S. Gordon, J. J. Jensen, S. Koseki, N. Matsunaga, K. A. Nguyen, S. Su, T. L. Windus, M. Dupuis and J. A. Montgomery, J. Comput. Chem., 1993, 14, 1347. Footnotes † Present address: Department of Electronic Chemistry, Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology, Nagatsuta, Midori-ku, Yokohama 226-8502, Japan. E-mail: yoshiro@echem.titech.ac.jp. ‡ The calculations of the Löwdin atomic charge (6-31G*//3-21G) for each nitrogen atom using the GAMESS program20 (2–0.1535, 3–0.1489, 4–0.1508, 4,4�-bipyridine –0.1893, 2,2�- dipyridylacetylene –0.1768, 3,3�-dipyridylacetylene –0.1879, 4,4�- dipyridylacetylene –0.1871) support the experimental results on proton transfer. CrystEngComm © The Royal Society of Chemis