The title carbazole derivative, C 13 H 9 NO, crystallizes with two independent molecules (A and B) in the asymmetric unit. The dihedral angle between the planar carbazole ring system and the aldehyde group (HC O) is 3.3 (2) in A and 7.5 (2) in B, indicating that the molecules are both nearly planar. In the crystal, the A and B molecules are linked by a C-HÁ Á ÁO hydrogen bond and stack along the b-axis direction. The structure was refined as a two component twin with a refined BASF value of 0.102 (2). Structure descriptionCarbazole derivatives are important compounds because of their wide range of biological activities, and also owing to their high electron affinity, hole transport properties and good planarity, which make them appropriate building blocks in the construction of chromophores for non-linear optical materials (Li et al.

The title compound, [Zn(NCS)2(C21H15N3)], crystallizes with three independent complex molecules in the asymmetric unit. In each complex molecule, the ZnIIatom is coordinated by three N atoms of a 4′-phenyl-2,2′:6′,2′′-terpyridine ligand, and by the N atoms of two NCS−anions. The ZnIIatoms are therefore five-coordinate, ZnN5, with distorted square-pyramidal geometries. In the crystal, the three independent molecules are linked by a series of offset π–π interactions [intercentroid distances vary between 3.680 (5) and 3.791 (5) Å], forming columns along thea-axis direction. The columns are linkedviaC—H...S interactions, forming a fence-like arrangement parallel to theabplane. A small region of disordered electron density was corrected for using the SQUEEZE routine inPLATON[Spek (2015).Acta Cryst.C71, 9–18], but the formula mass and unit-cell characteristics were not taken into account during the refinement.