Received 2 May 2011
The title compound, C26H36N2O2, was prepared by Horner olefination of p-dihexylaminobenzaldehyde and diethyl p-nitrobenzylphosphonate. It crystallizes with two independent molecules in the asymmetric unit. Both have similar geometries of the -systems but the conformations of all hexyl chains are different. Whereas one hexyl chain of the first molecule shows the typical all-anti conformation, the second is arranged in a gauche-anti-gauche-anti conformation with N-C-C-C, C-C-C-C, C-C-C-C and C-C-C-C torsion angles of -65.1 (4), 167.3 (3), 63.3 (4), and 179.4 (3)°. One of the hexyl chains in the other molecule has an anti-anti-gauche-anti conformation [N-C-C-C, C-C-C-C, C-C-C-C and C-C-C-C torsion angles = 179.6 (3), -179.8 (3), -68.7 (5) and -178.8 (4)°], the other starts with an anti-gauche-gauche sequence. Molecules A and B are composed of five planar subunits. The angle sums around the N atoms are in the range 356 (2)-360.0 (2)°. Torsion angles between these segments do not exceed 4.9 (4)°, except for one of the alkyl chains each [molecule A = 26.2 (4)°; molecule B = -6.0 (4)°]. The high planarity of the molecules and the short aniline C-N bonds [1.385 (3) Å in molecule A and 1.378 (3) Å in molecule B] indicate a strong electronic coupling through the stilbene unit. One methylene group is disordered over two positions with an occupancy ratio of 0.72:0.28.
For chromophores and fluorophores based on quadrupolar donor-acceptor-substituted stilbenoid systems, see: Detert & Sugiono (2005); Strehmel et al. (2003); Nemkovich et al. (2010). Similar aminonitrostilbenes had been prepared earlier, see: Pfeiffer et al. (1915); Chardonnens & Heinrich (1939); Meier et al. (2004). The optical properties of these dyes are strongly dependent on charge transfer and torsion angles, see: Baumann et al. (1977); Goerner (1998); Dekhtyar & Rettig (2007). Conjugated oligomers with basic sites are sensing materials for polarity and cations, see: Wilson & Bunz (2005); Zucchero et al. (2009). For a comparable compound, see: Fischer et al. (2011).
Data collection: APEX2 (Bruker, 2006); cell refinement: SAINT (Bruker, 2006); data reduction: SAINT; program(s) used to solve structure: SIR97 (Altomare et al., 1999); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: PLATON (Spek, 2009); software used to prepare material for publication: PLATON.
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: BT5539 ).
Financial support from the Deutsche Forschungsgemeinschaft is gratefully acknowledged.
Altomare, A., Burla, M. C., Camalli, M., Cascarano, G. L., Giacovazzo, C., Guagliardi, A., Moliterni, A. G. G., Polidori, G. & Spagna, R. (1999). J. Appl. Cryst. 32, 115-119.
Baumann, W., Deckers, H., Loosen, K. D. & Petzke, F. (1977). Ber. Bunsen Ges. Phys. Chem. 81, 799-804.
Bruker (2006). APEX2 and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA.
Chardonnens, L. & Heinrich, P. (1939). Helv. Chim. Acta, 22, 1471-82.
Dekhtyar, M. & Rettig, W. (2007). J. Phys. Chem. A, 111, 2035-2039.
Detert, H. & Sugiono, E. (2005). J. Lumin. 112, 372-376.
Fischer, J., Schmitt, V., Schollmeyer, D. & Detert, H. (2011). Acta Cryst. E67, o875.
Goerner, H. (1998). Ber. Bunsen Ges. Phys. Chem. 102, 726-737.
Meier, H., Gerold, J., Kolshorn, H. & Muehling, B. (2004). Chem. Eur. J. 10, 360-370.
Nemkovich, N. A., Detert, H. & Schmitt, V. (2010). Chem. Phys. 378, 37-41.
Pfeiffer, P., Braude, S., Kleber, J., Marcon, G. & Wittkop, P. (1915). Ber. Dtsch Chem. Ges. 48, 1777-809.
Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.
Spek, A. L. (2009). Acta Cryst. D65, 148-155.
Strehmel, B., Sarker, A. M. & Detert, H. (2003). ChemPhysChem, 4, 249-259.
Wilson, J. N. & Bunz, U. H. F. (2005). J. Am. Chem. Soc. 127, 4124-4125.
Zucchero, A. J., Tolosa, J., Tolbert, L. M. & Bunz, U. H. F. (2009). Chem. Eur. J. 15, 13075-13081.