title: Ammonium 4-methoxycinnamate.
abstract: In the title compound, NH(4)(+).C(10)H(9)O(3)(-), bimolecular layers of the anions are formed between layers of the cations. There are N-H.O hydrogen bonds between the ammonium ion and the carboxylate groups of the anions. In the crystal structure, the C=C moiety of the cinnamate ion makes an angle of 117.1 (2) degrees with that of the nearest neighbour, indicating that a pedal rotation is required before beta-type [2+2]-photodimerization can take place, which is the predominant mode of the photochemistry of this compound.
authors.affiliation: Department of Chemistry, Keio University, Hiyoshi 4-1-1, Kohoku-ku, Yokohama 223-8521, Japan. ohba@flet.keio.ac.jp
authors.forename: Shigeru
authors.initials: S
authors.lastname: Ohba
authors.forename: Yoshikatsu
authors.initials: Y
authors.lastname: Ito