title: Crystal structure of (E)-2-cyano-3-(12-methyl-12H-benzo[b]pheno-thia-zin-11-yl)acrylic acid.
abstract: In the title compound, C21H14N2O2S, a donor-acceptor type of benzo[b]pheno-thia-zine (bpz) derivative, the thia-zine ring adopts a boat conformation and the bond-angle sum at the N atom is 360.0°. The dihedral angle between the benzene ring and the naphthelene ring system fused to the thia-zine ring is 32.76 (5)°. In the crystal, carb-oxy-lic-acid inversion dimers linked by pairs of O-H⋯O hydrogen bonds generate R 2 (2)(8) loops. Aromatic π-π stacking [shortest centroid-centroid separaton = 3.5242 (13)Å] consolidates the structure and very weak C-H⋯O and C-H⋯N inter-actions also occur.
authors.affiliation: International Institute for Carbon-Neutral Energy Research (WPI-I2CNER), Kyushu University. 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan.
authors.forename: Motonori
authors.initials: M
authors.lastname: Watanabe
authors.affiliation: International Institute for Carbon-Neutral Energy Research (WPI-I2CNER), Kyushu University. 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan ; Department of Applied Chemistry, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan.
authors.forename: Tatsumi
authors.initials: T
authors.lastname: Ishihara
keywords: benzo[b]pheno­thia­zine derivative; crystal structure; hydrogen bonding; inversion dimers; π–π stacking