3,3,6,6-Tetramethyl-9-(1-methyl-1H-indol-2-yl)-1,2,3,4,5,6,7,8,9,10-decahydroacridine-1,8-dione

In the acridine system of the title molecule, C26H30N2O2, both cyclohex-2-enone rings adopt sofa conformations. The indole ring system is essentially planar, with a maximum deviation of 0.017 (2) Å for a bridgehead C atom. An intramolecular C—H⋯O hydrogen bond occurs. The molecules assemble into C(6) chains in the crystal by way of N—H⋯O hydrogen bonds.

In the acridine system of the title molecule, C 26 H 30 N 2 O 2 , both cyclohex-2-enone rings adopt sofa conformations. The indole ring system is essentially planar, with a maximum deviation of 0.017 (2) Å for a bridgehead C atom. An intramolecular C-HÁ Á ÁO hydrogen bond occurs. The molecules assemble into C(6) chains in the crystal by way of N-HÁ Á ÁO hydrogen bonds.

Comment
It is well known that ion channels play an important role in cell function. Potassium channels are one type of channel that regulate function in both excitable and nonexcitable cells. Potassium channel openers have the potential to restrain or prevent contractile responses of smooth muscle to excitatory stimuli. The main vasorelaxant mechanism of these openers is to increase the potassium efflux through opening plasmalemmal potassium channels, which repolarize and/or hyperpolarize the membrane. In addition to 1,4-dihydropyridine derivatives, bicyclo (quinoline) and tricyclo (acridine) analogs have also potassium channel modulator activity (Horiuchi et al., 2001;Crestanello et al., 2000;Frank et al., 1993;Berkan et al., 2002;Şimşek et al., 2004;Fincan et al., 2012;Gündüz et al., 2009;Li et al., 2011). The structure determination of the title compound, (I), was undertaken as part of our study of to 1,4-dihydropyridine derivatives.
The molecular structure of the title compound is shown in Fig. 1. Both (C1-C6 and C8-13) cyclohexene rings are in a sofa conformation with puckering parameters (Cremer & Pople, 1975)  In the crystal structure, adjacent molecules interact by way of an N-H···O hydrogen bond (Fig. 2, Table 1). This results in C(6) chains (Etter, et al., 1990) propagating along [010].
The precipitate which formed was filtered off and crystallized from ethanol. Crystals were grown by slow evaporation of a methanol solution.

Refinement
All H atoms were positioned geometrically and refined using a riding model with C-H = 0.95-1.00 Å; N-H = 0.88 Å and U iso (H) = 1.2 U eq (C, N) or 1.5 U eq (C methyl ). A rotating-group model was applied for the methyl groups.

Figure 1
The molecular structure of the title compound showing 30% probability displacement ellipsoids for non-H atoms.

Special details
Experimental. Absorption correction: CrysAlis RED, (Agilent, 2011) Empirical absorption correction using spherical harmonics, implemented in SCALE3 ABSPACK scaling algorithm. (Clark & Reid, 1995). Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes. Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.