In the title mol-ecule, C(18)H(13)FN(2)O(2), the hy-droxy group is involved in an intra-molecular O-H⋯N hydrogen bond. The naphthyl ring system and the benzene ring form a dihedral angle of 31.0 (2)°. In the crystal, N-H⋯O hydrogen bonds link the mol-ecules into chains propagating in [101].

The asymmetric unit of the title compound, C(12)H(18)F(4)Si(2), contains two independent mol-ecules, both lying on inversion centers. The C(arene)-Si distances are significantly longer than in the analogous non-fluorinated compound. The packing of the mol-ecules results in a herringbone motif in the ac plane.

In the title mol-ecule, C(12)H(18)Cl(2)N(2)O(2), the six-membered ring is in a chair conformation and the five-membered ring is in an envelope conformation. In the crystal, weak inter-molecular bifurcated (C-H)(2)⋯O hydrogen bonds connect mol-ecules into chains along [010].

In the title mol-ecule, C(23)H(18)O(5), the meth-oxy-substituted benzene ring makes dihedral angles of 65.12 (4) and 88.55 (4)° with the other two benzene rings. These two benzene rings form a dihedral angle of 45.70 (4)°. In the crystal, mol-ecules are linked into inversion dimers by pairs of weak C-H⋯O hydrogen bonds.

The title mol-ecule, C(14)H(18)Cl(4), possesses a crystallographically imposed inversion centre, which coincides with the centre of benzene ring. In the absence of classical inter-molecular inter-actions, van der Waals forces help the mol-ecules to pack in the crystal.

In the title mol-ecule, C(17)H(18)N(4)O, the two phenyl rings form a dihedral angle of 18.15 (17)°. In the crystal, pairs of inter-molecular N-H⋯O hydrogen bonds link the mol-ecules into centrosymmetric dimers. Weak inter-molecular C-H⋯O inter-actions further link the dimers into chains running along [010].

In the mol-ecule of the title compound, C(18)H(13)N(3), the 4,5-diaza-fluorenyl-idene unit is nearly planar and is oriented at a dihedral angle of 66.31 (1)° with respect to the benzene ring. In the crystal structure, mol-ecules are stacked regularly along the c axis.

The title compound C(18)H(16)N(2)S(2), crystallizes with two independent half-mol-ecules in the asymmetric unit, in one of which the thio-phene rings are disordered in a 0.67:0.33 ratio. Each independent mol-ecule lies across a crystallographic centre of symmetry. The dihedral angle between central (half) benzene ring and the thiophene ring is 11.82°.

In the title mol-ecule, C(18)H(11)FN(2)O(4), the fused four- ring system is essentially planar, with an r.m.s. deviation of 0.032 Å. In the crystal, mol-ecules are connected by π-π stacking inter-actions [centroid-centroid distances = 3.5684 (9) and 3.8247 (9) Å] into chains along [100].

In the title compound, C(26)H(18)O(2), the mol-ecule is located on a twofold rotation axis. The two naphthyl ring planes in the mol-ecule are nearly perpendicular to each other [dihedral angle = 82.42 (1)°. No classical hydrogen bonds or aromatic π-π stacking inter-actions were observed.