N,N-Dimethyl-4-(pyren-1-yl)aniline

In the title compound, C24H19N, the dimethylamino group is inclined to the benzene ring by 2.81 (9)°. Their mean plane makes a dihedral angle of 64.12 (2)° with the mean plane of the pyrene ring system [r.m.s. deviation = 0.031 (1) Å]. In the crystal, molecules are linked via C—H⋯π interactions, which connect neighbouring molecules into columns along the c axis.

In the title compound, C 24 H 19 N, the dimethylamino group is inclined to the benzene ring by 2.81 (9) . Their mean plane makes a dihedral angle of 64.12 (2) with the mean plane of the pyrene ring system [r.m.s. deviation = 0.031 (1) Å ]. In the crystal, molecules are linked via C-HÁ Á Á interactions, which connect neighbouring molecules into columns along the c axis.
ST thanks the DFG, SFB 755 and SFB 1073 for financial support. STV thanks G. Busse and L. Busse for technical help.

Comment
Electron donor acceptor molecules play an important role in the understanding of charge transfer processes. In the past decades, in order to gain more insight into electron transfer processes, extensive studies have been carried out on the optical behavior of systems consisting of donor acceptor groups linked by different bridges (Wasielewski, 1992;Willemse et al., 2000). These molecules are also ideal systems for studying the solvation dynamics and also for the demonstration of non-linear optical properties. Pyrene-N,N-dimethylaniline (PyDMA), is a compound in which the electron donor N,Ndimethylaniline (DMA) is covalently linked to the electron acceptor pyrene. Due to the lack of an extended bridge between the donor and acceptor in PyDMA, the physical characteristics of these groups strongly influence the electron transfer mechanism. This leads to a very unusual absorption and emission spectra in the optical regime and because of this PyDMA is considered to be a molecular diode where electron donor and electron acceptor moieties are twisted against each other modulating the electron charge transfer processes.

Experimental
Commercially available 1-aminopyrene after diazotization reaction was coupled with N,N-dimethylaniline according to the previously reported procedure (Dewar & Mole, 1956;Norman et al., 1958). The crude product was then purified on an aluminium oxide column with a mixture of cyclohexane/toluene as eluent and applying HPLC. Block-like colourless crystals of the title compound were obtained by crystallization from ethyl acetate/diethyl ether (2:1) by slow evaporation.

Refinement
The C-bound H-atoms were included in calculated positions and treated as riding atoms: C-H = 0.95 and 0.98 Å for CH and CH 3 H-atoms, respectively, with U iso (H) = 1.5U eq (C-methyl) and = 1.2U eq (C) for other H atoms.  The molecular structure of the title molecule, with atom labelling. Displacement ellipsoids are drawn at the 50% probability level.

Figure 2
The crystal packing of the title compound, viewed along the a axis, showing molecules linked by C-H···π interactions (dashed lines; see Table 1 for details).