CRYSTAL GROWTH & DESIGN
Halogen Bonding and Hydrogen Bonding Coexist in Driving Self-Assembly Process Shizheng
Zhu,*,†
Chunhui
Xing,†
Wei
Xu,‡
Guifang
Jin,†
and Zhanting
2004 VOL. 4, NO. 1 53-56
Li*,†
Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 354 Fenglin Lu, Shanghai 200032, China, and Ningbo University, Institute for Solid State Chemistry, Ningbo, Zhejiang, 315211 China Received July 8, 2003
ABSTRACT: A new class supramolecular architecture of 1,1,3,3-tetra-oxo-2-bromo-4,4,5,5,6,6-hexafluoro-1,3dithiacyclohexane 1 and 2-methylpyrazine has been assembled through both hydrogen bonding and halogen bonding. However, stronger or weaker bases or electron donors such as pyrazine and N,N,N ′,N ′-tetramethylenediamine (TMEDA) failed to give the corresponding supramolecule. The hydrogen bonding interaction is most frequently used to assemble organic molecules in the solid, liquid, or gas phase, and it plays an important role in stabilizing supramolecular aggregates.1 The halogen bonding that has received increasing attention recently is the attractive interaction between lone pairs possessing heteroatoms (N, O, S) and halogen atoms (I, Br, Cl).2 In the case of iodoperfluoroalkane, the halogen bonding is specific, directional, and strong enough to overcome the low affinity existing between perfluorocarbons (PFC) and hydrocarbons (HC) derivative, driving the selfassembly of two liquid components into a cocrystal at room temperature.3 We have described the oxygen-iodine interaction4 to give complexes with endless chains from R,ω-diiodo perfluoroalkanes I(CF2CF2)nI with 1,4-dioxane and HMPA. Resnati et al.5 also devised a competitive experiment to directly contrast the halogen bond and hydrogen bond in driving a self-assembly process between 1,4-diiodotetrafluorobenzene with 1,2-bis(4-pyridyl) ethane and hydroquinone. It was shown that when the recognition pattern controlling the self-assembly process can be based on either hydrogen bonding or halogen bonding, the latter can dominate over the former under appropriate conditions. The halogen bonding will single out the molecules that will be involved in the construction of supramolecular architectures. In this paper, we present the first example of hydrogen bonding and halogen bonding coexisting in driving a self-assembly process. Slow evaporation of an equivalent solution of 1,1,3,3tetra-oxo-2-bromo-4,4,5,5,6,6-hexafluoro-1,3-dithiacyclohexane 1 and 2-methyl pyrazine 2 in dichloromethane afforded a lightly red crystal 5 where two starting modules are present in a 1:1 ratio, which is independent of their stoichiometry in the solution (Scheme 1). Cocrystal 5 melts in a range of 109-112 °C, while the melting points of the starting materials 1 and 2 are 112 and -29 °C, respectively. The structure of the cocrystal was determined by spectral methods and X-ray diffraction analysis at room temperature (Figure 1).6 * Corresponding author (S.Z.) Fax: +86(21) 64166128. E-mail:
[email protected]. (Z.L.) Fax: +86(21) 64166128. E-mail: ztli@ mail.sioc.ac.cn. † Chinese Academy of Sciences. ‡ Ningbo University.
Figure 1. (a) Molecular structure of compound cocrystal 5. (b) Packing diagram of cocrystal 5. Table 1. Donor-Acceptor Interaction of Compound 1 and Cocrystal 5 compound
interaction type
distance (Å)
angels (deg)
1 5 1 5
C-Br‚‚‚O C-Br‚‚‚N C-H‚‚‚O N-H‚‚‚O
3.337(2) 3.063(1) 2.536(2) 2.180(3)
151.5(3) 169.6(2) 144.8(1) 153.9(2)
Pa
Qb
0.990 0.900
1.839 1.662
a P ) distance/sum of van der Waals radii for H, 1.20 Å; O, 1.52 Å; N, 1.55 Å; and Br, 1.85 Å. b Q ) distance/covalent bond length for N-Br, 1.843 Å and O-Br, 1.814 Å.
The packing map clearly showed that the intermolecular halogen bond (N4‚‚‚Br) and the hydrogen bond
10.1021/cg0300275 CCC: $27.50 © 2004 American Chemical Society Published on Web 10/30/2003
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Zhu et al. Scheme 1
Figure 2. (a) Molecular structure of compound 1. (b) Packing diagram of crystal 1.
(N-H‚‚‚O) coexisted in 5. The distance of the halogen bond N4‚‚‚Br is 3.063 Å, which is shorter than that of the sum of van der Waals radii (3.40 Å). The N4‚‚‚Br-C angle (169.6°) is approximately linear. Thus, the nitrogen atoms meet bromine atoms roughly in line with the C-Br bond, and it is consistent with an n f σ* electron donation from nitrogen to bromine. In a known example,7 the tetrabromoethylene and pyrazine adduct, the distance of the N‚‚‚Br halogen bond and the angle of C-Br‚‚‚N are 3.018 Å and 174.8°, respectively.7 Owing to the presence of a 2-methyl substitute, the 1-nitrogen atom of 2 is more basic than that of 4-nitrogen. Thus, it preferred to abstract the acidic 2-hydrogen of 1 rather than function as an electron donor toward the bromine atom of 1, forming the intermolecular hydrogen bond with one oxygen atom of the SO2 group.
The distance of (N1)-H‚‚‚O is 2.180 Å, and the angle of N1-H‚‚‚O is 153.9°. These values confirm the previous observation in similar systems and prove the presence of an attractive nonconvalent interaction between the atoms involved.8 The presence of halogen bonding in cocrystal 5 was also confirmed by comparing the IR spectra of 2 and 5. For example, the aromatic and aliphatic υC-H absorptions in the donor 2 appear at 3058 and 2963 cm-1, respectively; they are shifted to higher frequencies in cocrystal 5 (3074 and 2976 cm-1). Meanwhile, the pyrazine ring (υcdc) absorption appearing at 1581 cm-1 in pure 2 is moved to 1612 cm-1 in 5. These changes are correlated with a higher positive charge on the hydrogen and carbon atoms in the adduct 5 than in pure 2 as a result of the n f σ*9 electron donation from the nitrogen to the bromine atom and the protonation of the nitrogen atom. Analogously, the difference in chemical shifts of the 1H NMR spectra of compounds 2 and 5 [∆δH ) (δH in 5 - δH in 2) g 0.02 ppm] is another parameter for probing the strength of the interaction. The 19F NMR of compound 1 in CDCl3 consists of two second-order AB patterns with a 1:2 ratio. In CD3COCD3, however, it is an apparent first-order spectrum at -121.2 ppm (2 × CF2S) and -125.7 ppm (CF2C). For the cocrystal 5, its 19F NMR spectrum has only one little broad peak at -124.5 ppm. Module 1 in adduct 5 adopted a stable chair conformation as its pure form.10 It was interesting to notice that the packing map of compound 1 showed the presence of weak intermolecular halogen bonding (between C-Br‚‚‚O) and hydrogen bonding (between C-H‚‚‚O) (see Figure 2 and Table 1). However, when pyrazine 3a or R-cyano pyrazine 3b was used instead of 2 to react with 1 under the same conditions, no corresponding cocrystal was generated. It indicated that the halogen bonding alone (SP2N‚‚‚Br) could not drive the formation of the isolated cocrystal. N,N,N′,N′-Tetramethylenediamine (TMEDA) 4, which is a stronger base and electron donor than 2 and 3, has been widely used in self-assembly processes with R,ωdiiodoperfluoroalkane,11 1,4-diiodotetrafluorobenzene,5 1,2-diiodofluoro-ethene,12 and R,ω-dibromoperfluoroalkanes, etc.13 to form infinite one-dimensional networks. However, treatment of 4 with 1 in CH2Cl2 only gave a white precipitate, which has been characterized to be N,N,N ′,N ′-tetramethylenediamine dihydrobromide 6
Halogen and Hydrogen Bonding Coexist in Self-Assembly
Crystal Growth & Design, Vol. 4, No. 1, 2004 55
Figure 3. Molecular structure of compound 6. Packing map of molecular 6.
(yield: 72%) by spectral and X-ray crystal diffraction analyses (Figure 3).14 In this case, TMEDA acted only as a base to abstract an acidic hydrogen of 1 to form a dihydro (TMEDA) salt of SO2(CF2)3SO2C-Br, which decomposed to give 6. 19F NMR analysis of the remaining mother solution showed that the fluorine containing compounds were Br(CF2)3Br and HCF2CF2Br, etc. These results are similar to the observation in the literature in which the decomposition of (CF3SO2)2CBrK gave KF, CF3Br, and SO2 as major products.15 In conclusion, we have described a specific selfassembly process driven by coexisting hydrogen bonding and halogen bonding, in which two modules 1 and 2-methylpyrazine assembled to the programmed supramolecular architecture 5, whereas a stronger and weaker base or electron donors 3 and 4 failed to assemble with 1 affording the corresponding supramolecules. Our findings offer new opportunities in the design and manipulation of molecular aggregation processes and may be useful in many fields. Acknowledgment. This work was supported by the National Natural Science Foundation of China (NNSFC) (Nos. 20032010 and 90206005) and the Innovation Foundation of the Chinese Academy of Sciences for financial support. References (1) (a) Jeffrey, G. A. An Introduction to Hydrogen Bonding; Oxford University Press: Oxford, 1997. (b) Aacheroy, C. B.; Seddon, K. R. Chem. Soc. Rev. 1993, 22, 397. (2) (a) Legon, A. C. Angew. Chem. Int. Ed. 1999, 38, 2687. (b) Legon, A. C. Chem. Eur. J. 1998, 4, 1890. (c) Legon, A. C.; Metrangolo, P.; Pilati, T.; Resnati, G. New J. Chem. 2000, 24, 777-780. (3) (a) Messina, M. L.; Metrangolo, W.; Panzeri, E.; Ragg, E.; Resnati, G. Tetrahedron Lett. 1998, 39, 9069. (b) Desiraju, G. R. Angew. Chem. Int. Ed. 1995, 34, 2311.
(4) Chu, Q. L.; Wang, Z.; Huang, Q.; Yan, C.; Zhu, S. Z. J. Am. Chem. Soc. 2001, 123, 11069. (5) Corradi, E.; Meille, S. V.; Messina, M. T.; Metrangolo, P.; Resnati, G. Angew. Chem. Int. Ed. 2000, 39, 1782-1786. (6) Crystallographic data for cocrystal 5: formula C9H7BrF6N4O4S2; Mr ) 465.20; monoclinic, space group P-1/(2); temperature 293 K; a ) 7.3050 (15) Å, b ) 10.315(2) Å, c ) 10.847(2) Å, R ) 72.17(3)°, β ) 76.02(3)°, γ ) 84.32(3)°, V ) 754.7(3) Å3; Z ) 2, Dc ) 2.047 mg m-3, µ(MoKR) 3.087 mm-1; F(000) ) 456; θ/2θ scan mode 2.02 e θ e 27.5, 3405 collection reflections, 2843 independent, 231 refined parameters with I g 2σ(I), R1 ) 0.0522, wR2 ) 0.1102. 5: 1H NMR (CDCl3): δ ) 2.50 (broad, 1H, NH), 2.59 (s, 3H, CH3), 8.41 (s, 1H, ArH), 8.49 (s, 2H, ArH). 19F NMR (CDCl3): δ ) -124.4 (s, 4F, 2SO2CF2), -124.5 (s, 2F, CF2). MS (70 eV) m/z (%): 306/308 (C4F6HBrSO2+, 1.33/1.34), 150 (C3F6+, 6.4), 140/142 (SOCHBr+, 21.6/24.4), 100 (C2F4+, 74.6), 94 (C5H6N2+, 100.0). FT-IR (KBr): ν ) 3238(m), 3140(m), 3074(m), 2976(m), 2870(m), 1612(s), 1488(s), 1358(vs), 1374(s), 1268(s), 1201(s), 1160(s), 1139(s) cm-1. Elemental analysis calcd.: C 23.23, H 1.51, N 6.02, F 24.52. Found: C 23.47, H 1.80, N 5.86, F 24.32%. (7) Dahl, T. and Hassel, O. Acta Chem. Scand. 1968, 22, 2851. (8) (a) Hanks, T. W.; Metrangolo, P.; Resnati, G.; Walsh, R. B.; Pennington, W. T. Cryst. Growth Des. 2001, 1, 165. (b) Amico, V.; Meille, S. V.; Corradii, E.; Messina, M. T.; Resnati, G. J. Am. Chem. Soc. 1998, 120, 8261. (c) Ramasubb, N.; Parthasarathy, R.; Murray-Rust, P. J. Am. Chem. Soc. 1986, 108, 4308. (9) (a) Bertani, M. T.; Moiana, A.; Metrangolo, P.; Perez, E.; Pilatl, T.; Resnati, G.; Rico-Lattes, I.; Sassi, A. Adv. Mater. 2002, 14, 1197. (b) Ruokolainen, J.; Tanner, J. R.; Brinke, G.; Thomas, E. L.; Ikkala, O. Macromolecules 1998, 31, 3532. (c) Ruokolainen, J.; Saariaho, M.; Sermaa, R.; Brinke, G.; Thomas, E. L.; Ikkala, O. Macromolecules 1999, 32, 1152. (10) Crystallographic data for crystal 1: formula C4HBrF6O4S2; Mr ) 371.08; crystal system, orthorhombic; space group, Pnma; temperature 293 K; a ) 19.067(2) Å, b ) 8.1060(9) Å, c ) 6.6179(7) Å, V ) 1022.86(19) Å3; Z ) 4, Dc ) 2.410 mg m-3, µ(MoKR) 4.517 mm-1; F(000) ) 712; θ/2θ scan mode 2.14 e θ e 28.25°, 5928 collection reflections, 2213 independent, 159 refined parameters with I g 2σ(I), R1 ) 0.0485, wR2 ) 0.1148. (11) (a) Corradi, E.; Meille, S. V.; Messina, M. T.; Metrangolo, P.; Resnati, G. Tetrahedron Lett. 1999, 40, 7519. (b) Lunghi, A.; Cardillo, P.; Messina, M. T.; Metrangolo, P.; Panzeri, W.; Resnati, G. J. Fluorine Chem. 1998, 91, 191.
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(12) Burton, D. D.; Fontana, F.; Metrangolo, P.; Pilati, T.; Resnati, G. Tetrahedron Lett. 2003, 44, 645. (13) Zhu, S. Z.; Chu, Q. L.; Huang, Q. C. New J. Chem. 2003, 27, 1522. (14) Crystal data of compound 6: formula C6H18N2Br2; Mr ) 278.04; monoclinic, space group P2(1)/c; temperature 293 (2) K; a ) 5.4699 (10) Å, b ) 10.8006(19) Å, c ) 9.1189(16) Å, R ) 90°, β ) 95.445(3)°, γ ) 90°, V ) 536.30(17) Å3; Z )
Zhu et al. 2, Dc ) 1.722 mg m-3, µ(MoKR) 7.503 mm-1; F(000) ) 276; θ/2θ scan mode 2.93 e θ e 28.22, 3152 collection reflections, 1232 independent, 82 refined parameters with I g 2σ(I), R1 ) 0.0500, wR2 ) 0.1150. (15) Koshar, R. J.; Mitsch, R. A. J. Org. Chem. 1978, 38, 3358.
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