The crystal structure of 4′-{4-[(2,2,5,5-tetra­methyl-N-oxyl-3-pyrrolin-3-yl)ethyn­yl]phen­yl}-2,2′:6′,2′′-terpyridine

The terpyridine group of the title compound, C(31)H(27)N(4)O, assumes an all-transoid conformation and is essentially planar with the dihedral angles between the mean planes of the central pyridine and the two outer rings amounting to 3.87 (5) and 1.98 (5)°. The pyrroline-N-oxyl group commonly seen in such nitroxyls is found in the title structure and the mean plane of the pyrroline ring subtends a dihedral angle of 88.44 (7)° to the mean plane of the central pyridine ring. The intra­molecular separation between the nitrogen atom of the central pyridine unit of the terpyridine group and the nitroxyl group is 14.120 (2) Å. In the crystal, the mol­ecules are arranged in layers stacked along [001]. Slipped face-to-face π–π inter­actions between the pyridine rings are observed along this direction with the shortest centroid–centroid distances amounting to 3.700 (1) and 3.781 (1) Å. Furthermore, edge-on C—H⋯π inter­actions between the phenyl­ene rings of neighbouring mol­ecules are observed along this direction. A two-dimensional C—H⋯O hydrogen-bonded network is formed within the (010) plane. The shortest O⋯O separation between neighbouring mol­ecules is 5.412 (3) Å.