CRYSTAL GROWTH & DESIGN
A Novel Saturated Hydrogen Bridge Architecture in Supraminols Balakrishna R. Bhogala,† Venu R. Vangala,† Philip S. Smith,‡ Judith A. K. Howard,*,‡ and Gautam R. Desiraju*,†
2004 VOL. 4, NO. 4 647-649
School of Chemistry, University of Hyderabad, Hyderabad 500 046, India, and Department of Chemistry, University of Durham, South Road, Durham DH1 3LE, U.K. Received March 1, 2004;
Revised Manuscript Received April 25, 2004
ABSTRACT: Low-temperature X-ray analysis of two aminophenols reveals an interesting and novel saturated O-H‚‚‚N and N-H‚‚‚O hydrogen bond tube architecture. This pattern is topologically similar to the anion framework in the rare zeolite narsarsukite Na2TiOSi4O10. Crystal engineering, the design of organic solids with specified architecture and properties, continues to fascinate chemists.1 Ermer and Eling2 showed that O-H‚‚‚N and N-H‚‚‚O complementarity in amine alcohols leads to a super arsenic sheet (β-As) or super-black phosphorus (black-P) structure types. The hydrogen bond capabilities of N-H and O-H groups are fully “saturated” in these networks by N-H‚‚‚O and O-H‚‚‚N hydrogen bonds or bridges, called hereafter (and elsewhere) as N(H)O interactions. Hanessian and co-workers3 observed a one-dimensional N(H)O ladder with tetramer loops. Desiraju, Howard, and co-workers4 showed that the influence of particular molecular geometries can lead to lower dimensional “unsaturated” hydrogen bridge patterns (tetramer loop, infinite chain), in which the “free” N-H groups form N-H‚‚‚π interactions. Loehlin et al.5 classified saturated hydrogen bond (SHB) architecture into two types. These are the hexagonal chicken wire pattern A and the distinct ladder patterns B and C shown in Scheme 1. A comprehensive CSD survey6 (Version 5.24, including July 2003 updates and recent structures from the Hyderabad-Durham group4b) of SHB motifs in supraminols revealed that there are a total of 26 SHB structures with N(H)O interactions. Of these, 20 belong to the β-As category, one to the black-P type and the remaining five to the ladder arrangement B. There are also two other entries in the CSD pertaining to ladder C, but the overall interactions in these latter cases are unsaturated with free N-H groups being present. This communication reports a novel and hitherto unreported SHB N(H)O architecture in the pair of supraminols 3-[(E)-2-(4-aminophenyl)-1-ethenyl]phenol, 1, and 3-(4-aminophenethyl)phenol, 2. Inspection of the molecular structures of 1 and 2 shows a nearly 120° angle between the -OH and -NH2 groups4b (C-O, C-N angles for 1: 122.4°; 2: 124.1°, 123.2°), and hence they were expected to form the infinite chain ‚‚‚(N-H‚‚‚O-H‚‚‚)n structure seen in 3-aminophenol and elsewhere.4 However, the structures of 1 and 2 are very different (Figure 1) from those seen in other aminols.4b The molecules of 1 form centrosymmetric O-H‚‚‚N dimers (1.78 Å, 167.5°), which are further connected through N-H‚‚‚O bridges (2.08 Å, 152.3°) at the amine and hydroxy sites leading to a sheet structure via infinite N(H)O networking. These sheets further stack along the a-axis so that adjacent N(H)O infinite chains are cross-linked with N-H‚‚‚O interactions (2.16 Å, 151.9°) to give a SHB tube organization. It could be expected that 1 and 2 would be isostructural, and we have noted previously that the exchange of an * To whom correspondence should be addressed. E-mail: desiraju@ uohyd.ernet.in. † University of Hyderabad. ‡ University of Durham.
Scheme 1. Supramolecular Patterns with Saturated N(H)O Interactions: (A) Parallel Infinite Chains with Sawtooth Geometry Connected to Form β-As or Black-P Sheets. (B) and (C) SHB Ladders
Scheme 2
ethylene linker for an ethane linker has little effect on the molecular packing.4b In fact, while 1 crystallizes in the space group Pccn, 2 solves in the related, but lower symmetry space group Pna21 with Z′ ) 2.7 The structure of 2 is, in effect, pseudosymmetric to that of 1. The unit cell dimensions are similar with an isostructurality parameter Π8 of 0.0069, and the arrangement of molecules within the crystals is almost the same. NIPMAT plots and simulated powder spectra for 1 and 2 show the near identity of crystal packing in the two cases (see Supporting Information). The reader will observe that these structures can be considered as a narrow ribbon section of the β-As sheet that has been rolled up to form a tube. In the β-As sheet two infinite chains with sawtooth geometry are connected to form either O-H‚‚‚N or N-H‚‚‚O hydrogen bridges (Scheme 1). Here, the tube is completed with a saturation of the N(H)O interactions. However, this analogy to the β-As sheet is only partly valid because in the β-As sheet, the molecules lie above and below the sheet. In the tube structures of aminols 1 and 2 molecules must radiate from only one surface (the outside) of the tube. Still, in terms of hydrogen bond valence, the system is N(H)O saturated like the β-As sheet. Considering the column end-on, it can be seen that the cross-linked chains effectively generate twisted square
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Figure 1. 3-[(E)-2-(4-aminophenyl)-1-ethenyl]phenol 1: (a) infinite chain; (b) stacking down c-axis; and (c) adjacent infinite chains crosslink through N-H‚‚‚O interactions forming a tube. The nearly identical crystal structure of 3-(4-aminophenethyl)phenol 2 is noteworthy.9
Figure 2. Schematic of two infinite chains (offset dimers color coded as red and pink) running in a zigzag manner viewed down the a-axis. The chains are cross-linked via N-H‚‚‚O interactions (blue) to form a tube. Notice that the two -OH groups in the square motif (green) project toward the same side.
motifs that stack to form the tube (Figure 2). These square motifs are constructed with N-H‚‚‚O hydrogen bridges only (rather than a combination of O-H‚‚‚N and N-H‚‚‚O interactions) and hydroxy H atoms linking each square motif to the one below. In Hanessian’s structures3c the same interactions are found but one -OH group links to a square motif below, while the other links to the one above to form a helical ladder structure. In this way, the structures of 1 and 2 can be considered as containing elements of all three major synthons in this family (square motif, infinite chain, and β-As sheet).4b It is seen that the hydrogen bond pattern in 1 and 2 is topologically the same as that of the anion network in the rare zeolite variant narsarsukite Na4(TiO)2(Si8O20).10 It may also be noted that this network topology is not mentioned in Wells’ monumental compilation.12a Figure 3 shows the SHB tube structure in aminols 1 and 2 (D), the topology of Si atoms in narsarsukite (E) and the SiO4 tetrahedra-based structure of the zeolite (F). It may be noted that when Peacor and Buerger10a reported the structure of narsarsukite in 1962, they observed that it is based on a new arrangement of Si-tetrahedra. They described the structure as being made up of tubes having composition Si4O10 parallel to the c-axis and bonded by Tioctahedra. The Na atoms occupy voids running between the tubes and chains and have an irregular coordination of O atoms. Peacor and Buerger further write that “the most striking feature of the network is a multiple chain of linked silicon tetrahedra parallel to the c axis of a type unknown except in narsarsukite....it can be roughly described as a sequence of rings of 4 tetrahedra, linked together....to form a tube. It is also useful to note that the tube can be formed by rolling up a hexagonal sheet of
Figure 3. (D) SHB tube in 1 and 2. (E) Anion network in narsarsukite. The nodes are Si-atoms. (F) Anion network showing also SiO4 tetrahedra.
composition Si4O10 of the type that occurs in the phyllosilicates.” We note that the tube of N(H)O interactions in aminols 1 and 2 is formed in exactly the same way by “rolling up a hexagonal sheet” of composition N(H)O of the type that occurs in the β-As supraminols. The formation of topologically identical and rare networks in compounds that belong to entirely differing domains is striking and shows the universality of closepacking in crystals.11 While the network arrangement in a crystal may be rationalized in terms of the constituent interactions, entirely different interaction types may lead to the same network. In other words, the network structure of a crystal is a higher-level property and the description of any crystal structure as a network is more likely to bring out more meaningful similarities and differences between it and other crystal structures.12 From a crystal engineering standpoint, it is interesting to note that while the structures of 1 and 2 appear at first glance to be very different from other supraminols, they may actually be described using simultaneously all three important synthons in this family. This demonstrates that it is the supramolecular synthons, the kinetically favored fragments, that are the real kernel of a crystal structure.13
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Finally, a study of the 3-amino-4-hydroxy analogues of 1 and 2 would also be interesting. Would these compounds crystallize in the infinite chain motif or in a tube structure similar to that seen in 1 and 2? Either way, these compounds should help to understand how the tube structures relate to the other structures observed in the supraminol family. Eventually, these results should hopefully lead to a comprehensive structural model that would explain the crystal structures of all simple compounds that contain amino and hydroxy fragments in equal stoichiometries. Acknowledgment. V.R.V. thanks the CSIR for a fellowship. B.R.B. thanks the UGC for a fellowship. P.S.S. thanks EPSRC for a studentship. J.A.K.H thanks the EPSRC for a Senior Research Fellowship. G.R.D. thanks the CSIR and DST for support of his research programs. We thank Dr. C. K. Broder for helpful discussions. Supporting Information Available: Synthetic procedures, NIPMAT plots, simulated powder spectra, ORTEP diagrams, structure solution and refinement, atomic coordinates, bond lengths and angles, anisotropic parameters for aminols 1 and 2, and crystallographic information files. This material is available free of charge via the Internet at http://www.pubs.acs.org.
References (1) Desiraju, G. R. Crystal Engineering. The Design of Organic Solids; Elsevier: Amsterdam, 1989. (2) Ermer, O.; Eling, A. J. Chem. Soc., Perkin Trans. 2 1994, 925-944. (3) (a) Roelens, S.; Dapporto, P.; Paoli, P. Can. J. Chem. 2000, 78, 723-731. (b) Dapporto, P.; Paoli, P.; Roelens, S. J. Org. Chem. 2001, 66, 4930-4933. (c) Hanessian, S.; Saladino, R. in Crystal Design. Structure and Function. Perspectives in Supramolecular Chemistry; Desiraju, G. R., Ed.; Wiley: New York, 2003; Vol. 7, pp 77-151. (4) (a) Allen, F. H.; Hoy, V. J.; Howard, J. A. K.; Thalladi, V. R.; Desiraju, G. R.; Wilson, C. C.; McIntyre, G. J. J. Am. Chem. Soc. 1997, 119, 3477-3480. (b) Vangala, V. R.; Bhogala, B. R.; Dey, A.; Desiraju, G. R.; Broder, C. K.; Smith, P. S.; Mondal, R.; Howard, J. A. K.; Wilson, C. C. J. Am. Chem. Soc. 2003, 125, 14495-14509. (5) Loehlin, J. H.; Franz, K. J.; Gist, L.; Moore, R. H. Acta Crystallogr. 1998, B54, 695-704. (6) (a) β-As sheet: AMPHOL01, HIBFUT, NISMAD, PITYAS, PITYEW, PITYIA, PITYOG, PITZAT, SARDAQ, SARDIY, SARDOE, SARJUQ, ZAPFAX, ZAPFEB, and six β-As structures reported by us previously: see ref 4b and compounds 2, 4, 2a, 2b, 2d, and 1b of that paper. (b) Black-P sheet: JAKKEL (c) SHB ladder: GUCQUQ, GUCREB, GUCRIF, HYDETH, ZAVXAV. (d) SHB ladder in unsaturated supraminols include: PIWXOI, PIWXUO.
(7) Crystal data for 1: C14H13NO, orthorhombic, Pccn (no. 56), a ) 11.4815(5) Å, b ) 26.0534(16) Å, c ) 7.1885(4) Å, R ) β ) γ ) 90°, V ) 2150.3(2) Å3, Z ) 8, Dcalc ) 1.305 mgm-3, T ) 120(2) K, µ ) 0.082 mm-1, GOF ) 0.906, 2θ° ) 1.5626.99, 11281 measured, 2354 independent, 1474 observed (I > 2σ1) reflections, R1 ) 0.0416 and wR2 ) 0.0838 (for I > 2σ1). Crystal data for 2: C14H15NO, orthorhombic, Pna21 (no. 33), a ) 7.6679(2) Å, b ) 26.1975(6) Å, c ) 11.1698(2) Å, R ) β ) γ ) 90°, V ) 2243.79(9) Å3, Z ) 8, Dcalc ) 1.263 mgm-3, T ) 120(2) K, µ ) 0.079 mm-1, GOF ) 0.929, 2θ° ) 1.55-27.00, 24522 measured, 4897 independent, 3673 observed (I > 2σ1) reflections, R1 ) 0.0398 and wR2 ) 0.0796 (for I > 2σ1). The X-ray data were collected on a Bruker SMART-6000 diffractometer (compounds 1 and 2) using Mo KR radiation. The structure solution was by direct methods and refinements on F2 with SHELXTL programs. The hydroxy and amine hydrogen atoms were located in difference Fourier maps and refined isotropically. The other hydrogen atoms were fixed in geometrically sensible positions. (8) (a) Lowdin, P.-O. J. Chem. Phys. 1950, 18, 365-375. (b) Fa´bia´n, L.; Ka´lma´n, A. Acta Crystallogr. 1999, B55, 1099-1108. (9) Pertinent hydrogen bridges for 2: O-H‚‚‚N (1.75 Å, 167.5°; 1.82 Å, 173.4°), N-H‚‚‚O (2.01 Å, 157.6°; 2.15 Å, 154.8°; 2.18 Å, 152.9°; 2.28 Å, 139.7°). (10) (a) Peacor, D. R.; Buerger, M. J. Am. Mineral. 1962, 47, 539-556. (b) Ribeiro, F. R.; Rodrigues, A. E.; Rollmann, L. D.; Naccache, C. Zeolites: Science and Technology; E80, NATO ASI Series: Boston, 1984. (11) Reddy, D. S.; Craig, D. C.; Desiraju, G. R. J. Chem. Soc., Chem. Commun. 1995, 339-340. (12) Selected references that describe network structures include: (a) Wells, A. F. Structural Inorganic Chemsitry, 5th ed.; Oxford University Press: Oxford, 1984. (b) Bernstein, J.; Davis, R. E.; Shimoni, L.; Chang, N.-L. Angew Chem., Int. Ed. Engl. 1995, 34, 1555-1573. (c) Desiraju, G. R. Chem. Commun. 1997, 1475-1482. (d) Batten, S. R.; Robson, R. Angew. Chem., Int, Ed. 1998, 37, 1460-1494. (e) Leininger, S.; Olenyuk, B.; Stang, P. J. Chem. Rev. 2000, 100, 853-908. (f) Moulton, B.; Zaworotko, M. J. Chem. Rev. 2001, 101, 1629-1658. (g) Biradha, K. CrystEngComm 2003, 5, 374-384. (h) Yaghi, O. M.; O’Keeffe, M.; Ockwig, N. W.; Chae, H. K.; Eddaoudi, M.; Kim, J. Nature 2003, 423, 705-714. (i) Oh, M.; Carpenter, G. B.; Sweigart, D. A. Acc. Chem. Res. 2004, 37, 1-11. (13) Desiraju, G. R. Angew. Chem., Int. Ed. Engl. 1995, 34, 2311-2327.
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