10-(Prop-2-yn-1-yl)-2,7-diaza­phenothia­zine

In the title mol­ecule [systematic name: 10-(prop-2-yn-1-yl)dipyrido[3,4-b:3′,4′-e][1,4]thia­zine], C(13)H(9)N(3)S, the dihedral angle between the two pyridine rings is 146.33 (7)° and the angle between two halves of the thia­zine ring is 138.84 (8)°, resulting in a butterfly shape for the tricyclic system. The central thia­zine ring adopts a boat conformation, with the 2-propynyl substituent at the thia­zine N atom located in a pseudo-equatorial position and oriented to the concave side of the diaza­phenothia­zine system. In the crystal, mol­ecules are arranged via π–π inter­actions between the pyridine rings [centroid–centroid distances = 3.838 (1) and 3.845 (1) Å] into stacks extending along [001]. There are C—H⋯C and C—H⋯N inter­actions between mol­ecules of neighbouring stacks.