摘要:
Reproducible phenazine molecular stacks Results and discussion Venkat R. Thalladi,a Tanja Smolka,b Roland Boese*a and Reiner Sustmann*b a Institut für Anorganische Chemie, Universität-GH Essen, Universitätsstraße 5-7, D-45117 Essen, Germany. E-mail: boese@structchem.uni-essen.de b Institut für Organische Chemie, Universität-GH Essen, Universitätsstraße 5-7, D-45117 Essen, Germany. E-mail: sustmann@oc1.orgchem.uni-essen.de Received 11th May 2000, Accepted 6th June 2000, Published 20th June 2000 Single crystal X-ray diffraction analyses of the 2 : 1 complexes of phenazine with hydroquinone and 1,5-dihydroxynaphthalene and the 3 : 1 complex of phenazine with 4,4�-dihydroxybiphenyl have been performed. It is shown that in these complexes and also in the 3 : 1 complex of phenazine with 5,10-dihydrophenazine, phenazine forms a host framework consisting of onedimensional channels.The variation of guest molecules and attendant variations in the hydrogen bond patterns, and the reproducibility of phenazine molecular stacks are described. HQ was slowly evaporated. X-ray diffraction analysis of complex 1 (Table 1) showed that it belongs to the space group 1 P with the HQ molecules positioned on inversion centres and phenazine molecules located on general positions. While both the OH groups of HQ act as O–H···N hydrogen bond donors, only one of the two N atoms in phenazine acts as an O–H···N acceptor. Thus each HQ molecule is linked to two phenazine molecules through O– H···N hydrogen bonds (Table 2) leading to a discrete O– H···N assembly.The non-participation of one of the N atoms in O–H···N hydrogen bonding immediately suggests the possibility of the formation of weaker hydrogen bonds.9 Indeed the second N atom interacts with a C–H group and forms a C–H···N hydrogen bond. The N atom that accepts the O–H···N bond also accepts a C–H···N, and therefore there are two C–H···N bonds given in Table 2. It is essential to analyse complex 1 beyond these obvious hydrogen bond patterns to understand its intricate structural features which are displayed in Fig. 1a–c. It is convenient to dissect the crystal packing of 1 into three roughly orthogonal directions which may be depicted with (non-crystallographic) x, y and z axes (Fig. 1a). The above described O–H···N/C–H···N hydrogen bonds between HQ and phenazine molecules govern the molecular assembly along the x-axis leading to a kind of tape structure (Fig. 1b).Adjacent tapes along the z-axis may be said to form a twodimensional network in which phenazine molecules form continuous stacks (stacking separations: 3.442/3.714 and 3.517/3.737 Å)10 and the HQ molecules are connected by edge-to-edge C–H···O hydrogen bonded dimers.11 The HQ and phenazine molecules are inclined at 85°. Packing in the third direction, that is along the y-axis, may now be considered. The short edges of phenazine molecules are directed at the faces of HQ molecules in this direction leading to the formation of C–H···O hydrogen bonds and edge-to-face (or C–H···p)12 aromatic interactions (Fig.1c). Introduction There has been much recent interest in the use of phenazine as a template in crystal engineering. The electron rich aromatic system in phenazine enables it to be a good p- donor and the disposition of the two aromatic N atoms in a defined geometry enables it to be a good hydrogen bond acceptor. Accordingly, phenazine has been employed in the design of charge-transfer complexes1,2 and hydrogen bonded assemblies.3,4 Our own work focussed on the use of phenazine based hydrogen bonded co-crystals in photochromic applications and the development of crystal engineering strategies.5–8 In this work we report the crystal structures of two 2 : 1 complexes of phenazine with hydroquinone (HQ) and 1,5-dihydroxynaphthalene (DHN) and one 3 : 1 complex of phenazine with 4,4�- dihydroxybiphenyl (DHBP).We compare these structures with that of the 3 : 1 complex of phenazine and 1,5- dihydrophenazine (DHP) and illustrate that phenazine molecular stacks are a common feature in these structures. The present work was initiated when, as part of exploring the molecular complexes of phenazine with various hydrogen bond donors, it had been found that phenazine forms a 2 : 1 molecular complex (1) with HQ, rather than a 1 : 1 complex as would be expected from O–H···N hydrogen bond requirements (two N atoms in phenazine and two OH groups in HQ). Single crystals of complex 1 (mp 234–236 °C) were obtained when an ethyl acetate solution containing equimolar mixture of phenazine and DOI: 10.1039/b003788p CrystEngComm, 2000, 17Table 1 Crystal data and measurement details for 1, 3 and 4 1 3 4 (C12H8N2)2·C6H6O2 470.52 298 Triclinic Emp.formula Formula wt. T/K Crystal system Space group 1 P a/Å b/Å c/Å a/° b/° g/° ZV/Å3 N-totala N-indep.b Rint 7.286(2) 7.3415(6) 9.2844(4) 9.004(2) 9.5933(8) 9.4909(5) 9.239(2) 10.1204(8) 10.7853(5) 77.42(1) 87.680(2) 76.669(1) 74.83(3) 70.207(2) 87.181(1) 86.326(9) 79.333(2) 82.234(1) 1 1 1 571.0(3) 658.88(9) 916.12(8) 2514 5105 7154 1997 2208 3091 0.014 0.058 0.021 0.039 0.061 0.060 0.095 0.171 R1 awR2 0.133 Number of reflections collected. b Number of independent reflections. Click here for full crystallographic data (CCDC no. 1350/22).Table 2 Geometrical parameters for various intermolecular interactions in 1, 3 and 4 Interaction Complex 1 O–H···N C–H···N C–H···N C–H···O C–H···O C–H···pc C–H···O 3 O–H···N C–H···N C–H···N C–H···O C–H···O C–H···pc C–H···pc C–H···O 4 O–H···N C–H···N C–H···N C–H···N C–H···O C–H···O C–H···O C–H···pc C–H···pc C–H···O 2.58 3.648 171 a The O–H and C–H bond lengths are normalised to standard neutron distances. b The direction along which an interaction is formed. c The parameters are calculated to the ring centroid. The angle between H···centroid vector and the acceptor plane is also given in parentheses in the D–H···A column. H···A/Åa 1.84 2.64 2.64 2.42 2.45 3.04 2.95 1.85 2.51 2.69 2.76 2.95 2.73 2.79 2.55 1.84 2.46 2.58 2.69 2.79 2.87 2.95 2.76 2.81 (C12H8N2)3·C12H10O2 726.81 298 Triclinic (C12H8N2)2·C10H8O2 520.57 298 Triclinic 1 P D–H···A/° D···A/Å 172 140 129 156 159 130 (24) 170 2.815 3.542 3.424 3.441 3.481 3.829 4.021 171 137 129 174 125 133 (13) 142 (18) 137 2.824 3.378 3.477 3.839 3.683 3.559 3.705 3.428 177 155 142 129 146 163 125 130 (20) 133 (19) 2.824 3.468 3.496 3.472 3.743 3.921 3.680 3.555 3.640 1 P Directionb xxxyyyzxxxyyyyzxxxxyyyyyzFig. 1 Crystal packing of complex 1 dissected into the (noncrystallographic) x, y and z axes.(a) View down the z-axis: notice the arrangement of the phenazine stacks on a square-grid and the channels thus formed. Note that the HQ molecules are oriented in a perpendicular manner within the channels. Hydrogen bonds are not drawn for clarity. (b) View down the y-axis: notice the O–H···N/C– H&mid··N tapes along the x-axis and, the phenazine stacks and C–H···O dimers of HQ along the z-axis. (c) View down the x-axis: notice the C–H···O and edge-to-face (C–H···p) interactions along the yaxis. Click images or here to view the 3D crystal structure of 1. Alternatively, the structure of 1 may be viewed as forming from the juxtaposition of phenazine stacks on a square grid with HQ molecules filling the channels thus formed.It may then be envisaged that phenazine forms a host network into which HQ molecules enter as guests. In this context it is pertinent to compare the structure of 1 with that of the 3 : 1 complex (2) between phenazine and DHP which has been recently published.7 The structure of 2 is displayed in Fig. 2a–c and its overall similarity to the structure of 1 may be easily noted. Both of the structures (1 and 2) consist of the host network made of phenazine stacks, with the donor molecules located in the channels in a perpendicular inclination with respect to the phenazine molecules. It should be noted that not all complexes of phenazine with Fig. 2 Crystal packing of complex 2 dissected into the (noncrystallographic) x, y and z axes.(a) View down the z-axis: notice the arrangement of phenazine stacks on a square-grid and the channels thus formed. Note that the DHP molecules are oriented in a perpendicular manner within the channels. Hydrogen bonds are not drawn for clarity. (b) View down the y-axis: notice the N– H···N/C–H···N tapes along the x-axis and phenazine stacks along the z-axis. (c) View down the x-axis: notice the edge-to-face arrangement along the y-axis. Compare the equivalent parts in Fig. 1 and 2 and notice the similarities. The structure of 2 has been published recently.7 hydrogen bond donor molecules possess a similar structure. For example, the 3 : 2 complex of phenazine with 2,2�- dihydroxybiphenyl has an entirely different structure.6 From the analysis of the structures of 1 and 2 it may be reasoned that the similarities between these two structures arise due to the combination of the following effects: (a) the HQ and DHP molecules are bis-hydrogen bond donors, (b) the hydrogen bonding OH or NH groups are positioned in an antiparallel manner, and (c) the HQ and DHP molecules are aromatic and flat.13In order to test the validity of the above reasoning we have decided to vary the donor molecules while maintaining the factors involved in the above three effects.We planned the variation in two ways, viz. (a) to expand (or widen) and (b) to elongate the HQ moiety. Thus we have chosen 1,5- dihydroxynaphthalene (DHN) and 4,4�-dihydroxybiphenyl (DHBP) as expanded and elongated variants of HQ, respectively.We believe that these variations are large enough to test the robustness of the host framework. Fig. 3 Crystal packing of complex 3 dissected into the (noncrystallographic) x, y and z axes. (a) View down the z-axis: notice the arrangement of phenazine stacks on a square-grid and the channels thus formed. Note that the DHN molecules are oriented in a perpendicular manner within the channels. Hydrogen bonds are not drawn for clarity. (b) View down the y-axis: notice the O– H···N/C–H···N tapes along the x-axis and, phenazine stacks and C– H···O dimers of DHN along the z-axis. (c) View down the x-axis: notice the C–H···O and edge-to-face (C–H···p) interactions along the y-axis. Compare the equivalent parts in Fig. 1, 2 and 3 and notice the similarities and also slight variations.Click images or here to view the 3D crystal structure of 3. Complexation experiments of DHN and DHBP with phenazine have been carried out. While phenazine–DHN assembly leads to a 2 : 1 complex (3), a 3 : 1 complex (4) results from phenazine–DHBP assembly. Single crystals of 3 (mp 253–254 °C) and 4 (mp 199–201 °C) suitable for Xray diffraction analysis were grown from acetone solutions containing equimolar quantities of the constituents. The crystal structures of complexes 3 and 4 (Table 1) are shown in Fig. 3a–c and 4a–c respectively, and their packing patterns are also dissected into mutually perpendicular (non-crystallographic) x, y and z axes. The O–H···N/C– H···N assembly in complex 3 is similar to that observed in complex 1, and generates a tape structure along the x-axis (Fig.3b). Again the aggregation of these tapes along the zaxis leads to a two-dimensional network wherein the phenazine molecules form continuous stacks (stacking parameters: 3.429/3.912 and 3.506/3.807 Å) and DHN molecules are related by C–H···O hydrogen bonded dimers. However the pattern of C–H···O dimer in 3 is slightly different from that seen in 1 and the inclination between the DHN and phenazine molecules is 70° (related value in complex 1 is 85°). The packing in the third direction (along the y-axis, Fig. 3c) is governed by edge-to-face (or C–H···p) and C–H···O interactions. While C–H···p interactions are shorter in 3 the C–H···O bonds are shorter in 1 (Table 2) in this direction.This is because the DHN molecule is wider and p-electron rich compared to the HQ molecule. Despite these minor packing differences between 1 and 3, a view down the z-axis clearly indicates their overall packing similarity (Fig. 1a and 3a). The similarity between complexes 1 and 3 is indicated at a gross level by their 2 : 1 stoichiometry. Complex 4 on the other hand contains the constituents in 3 : 1 proportions suggesting some essential differences in its packing. Indeed complex 4 is distinct from complexes 1 and 3 in its hydrogen bond networks.14 In 4, the DHBP molecule and one of the two symmetry independent molecules of phenazine are located on inversion centres and are connected by O–H···N hydrogen bonds to generate an infinite, linear O–H···N bonded array.This is in contrast to the discrete O–H···N assembly seen in complexes 1 and 3. The second phenazine molecule is located on a general position and both of its N atoms form C–H···N hydrogen bonds with the C–H groups of DHBP molecule. Notwithstanding the differences in hydrogen bond networks, the structure of 4 can be dissected into (noncrystallographic) x, y and z directions as in 1 and 3. The pattern of O–H···N and C–H···N interactions described above is such that each DHBP molecule is linked to six phenazine molecules (two through O–H···N and four through C–H···N). The O–H···N/C–H···N assembly may be said to generate a tape structure along the x-axis (Fig.4b). These tapes aggregate along the z-axis (as in 1 and 3) and generate a two-dimensional network within which the phenazine molecules form continuous stacks (stacking parameters: 3.42/3.74 and 3.39/3.83 Å) and DHBP molecules are related by C–H···O hydrogen bonded dimers. The C–H···O dimer pattern is similar to that in 1. The DHBP molecule is inclined with respect to the two symmetry independent phenazine molecules at 71 and 73° (cf. 85 and 70° in 1 and 3). Edge-to-face (or C–H···) and C– H···O interactions contribute to the packing in the third direction (along the y-axis, Fig. 4c). As in complex 3 the C–H··· interactions are shorter than C–H···O bridges in complex 4 (Table 2). A view down the z-axis (Fig. 4a) shows the structural similarity between complexes 1–4.Fig.4stal packing of complex 4 dissected into the (noncrystallographic) x, y and z axes. (a) View down the z-axis: notice the arrangement of phenazine stacks on a square-grid and the channels thus formed. Note that the DHBP molecules are oriented in a perpendicular manner within the channels. Hydrogen bonds are not drawn for clarity. (b) View down the y-axis: notice the O– H···N/C–H···N tapes along the x-axis and, phenazine stacks and C– H···O dimers of DHBP along the z-axis. (c) View down the x-axis: notice the C–H···O and edge-to-face (C–H···p) interactions along the y-axis. Compare the equivalent parts in Fig. 1–4 and notice the similarities and also slight variations. Click images or here to view the 3D crystal structure of 4.We shall now look at the phenazine host frameworks in 1– 4. In all of the cases the phenazine stacks may be imagined to be located on a two-dimensional square-grid. The grid dimensions vary slightly from complex to complex and are in the range of 9–10 Å (the distance between two nearest grid points) and 80–100° (the angle between three nearest grid points). In all of these cases the phenazine molecules in the adjacent stacks are in parallel planes.15 The edges of one phenazine molecule are fitted into the edges of a neighbouring molecule on this grid, and the phenazine stacks are sustained by these edge-to-edge aromatic contacts. We may now look at the host–guest interactions. While the essential interactions between the phenazine framework and the guest molecules are the same in all the structures, there are some minor but non-insignificant differences within the interaction patterns.For example, while the dimer pattern of C–H···O bonds along the z-axis is similar for HQ and DHBP (in 1 and 4), it is different for DHN (in 3). These differences arise as a consequence of the optimisation of weak interactions (C–H···O, C–H···N and C–H···p). Conclusion A comparison of complexes 1–4 reveals that the host architecture of phenazine is robust (in that it is always formed) and also flexible (in that stacking distances, grid separations and mutual inclinations between phenazine molecules are varied). These complexes illustrate that the width and length of the guests can be varied at will, provided these variations take into account that the resultant guest molecule (a) is a bis donor with two donor groups in anti-parallel orientation (to ensure the hydrogen bond connections with phenazine stacks along the x-axis) and (b) is also flat and p-electron rich (to ensure the C–H··· p interactions along the y-axis).In addition, C–H···N hydrogen bonds play a key role in the supramolecular assembly along the x-axes in complexes 1–4. Reproducibility is a key feature in crystal engineering16 and consistent formation of phenazine molecular stacks in complexes 1–4, despite significant variations in the guests, suggests that these stacks can be used in the reliable design of desired structures.If non-centrosymmetry can be introduced into the phenazine based host–guest architecture (e.g., by selecting a non-centrosymmetric guest) this could have potential applications in non-linear optics.17 Acknowledgements This work was supported by the Deutsche Forschungsgemeinschaft (SFB-452) and the Fonds der Chemischen Industrie. VRT thanks the Alexander von Humboldt foundation for a post-doctoral fellowship. References 1 N. Karl, W. Ketterer and J. J. Stezowski, Acta Crystallogr., Sect. B, 1982, B38, 2917. 2 C. V. K. Sharma and R. D. Rogers, Cryst. Eng., 1998, 1, 139. 3 V. R. Pedireddi, W. Jones, A. P. Chorlton and R. Docherty, Chem. Commun., 1996, 997. 4 E. Batchelor, J. Klinowski and W. Jones, J. Mater. Chem., 2000, 10, 839.5 T. Smolka, R. Sustmann and R. Boese, J. Prakt. Chem., 1999, 341, 378 6 T. Smolka, R. Boese and R. Sustmann, Struct. Chem., 1999, 10, 429. 7 V. R. Thalladi, T. Smolka, A. Gehrke, R. Boese and R. Sustmann, New J. Chem., 2000, 24, 143. 8 T. Smolka, T. Schaller, R. Sustmann, D. Bläser and R. Boese, J. Prakt. Chem., 2000, 342, in the press. 9 G. R. Desiraju and T. Steiner, Weak Hydrogen Bond in Structural Chemistry and Biology, Oxford University Press, Oxford, 1999. 10 For p-stacking interactions the geometrical parameters are given as the interplanar distance + the distance between the centroids. In all of the stacking interactions reported in this work the interplanar angles are in the range 0 to 2°.11 (a) C. E. Marjo, M. L. Scudder, D. C. Craig and R. Bishop, J. Chem. Soc., Perkin Trans. 2, 1997, 2029; (b) V. T. Nguyen, A. N. M. M. Rahman, R. Bishop, D. C. Craig and M. Scudder, Aust. J. Chem., 1999, 52, 1047. 12 M. Nishio, M. Hirota and Y. Umezawa, The CH/ Interaction: Evidence, Nature and Consequences, Wiley-VCH, New York, 1998. 13 The two OH groups in 2,2�-dihydroxybiphenyl are not in an anti-parallel disposition and therefore the structure of its complex with phenazine (ref. 6) is different from those of 1 and 2. 14 Complex 4 is similar to complex 2 in many respects for the same reason (3 : 1 stoichiometry). 15 A similar phenazine host network exists in the crystal structure of the 1 : 1 complex between phenazine and oxalic acid (ref. 8). However, the phenazine molecules in adjacent stacks are inclined at 27°. 16 G. R. Desiraju, Angew. Chem., Int. Ed. Engl., 1995, 34, 2311. 17 J. Hulliger, P. J. Langley, O. Konig, S. W. Roth, A. Quintel and P. Rechsteiner, Pure Appl. Opt., 1998, 7, 221. CrystEngComm © The Royal Society of Chemistry 20
ISSN:1466-8033
DOI:10.1039/b003788p
出版商:RSC
年代:2000
数据来源: RSC