title: Dimethyl 2-[(acridin-9-yl)methyl-idene]malonate.
abstract: In the title compound, C(19)H(15)NO(4), the acridine system is essentially planar (r.m.s. deviation = 0.015 Å). The crystal packing exhibits π-π inter-actions between pairs of centrosymmetric mol-ecules, one of them between the central heterocyclic rings and others between the outer benzene rings of the acridine systems, with centroid-centroid distances of 3.692 (1) and 3.754 (1) Å, respectively. These pairs are further linked by additional π-π inter-actions along the a-axis direction through one of the two outer benzene ring of neighboring mol-ecules, with a centroid-centroid distance of 3.642 (2) Å.
authors: Laboratório de Imunopatologia Keizo Asami (LIKA), Departamento de Bioquímica, Universidade Federal de Pernambuco, 50670-901 Recife, PE,  Brazil.
authors: Sinara M V
authors: SM
authors: de Almeida
authors: Ivan R
authors: IR
authors: Pitta
authors: Maria do Carmo A
authors: Mdo C
authors: de Lima
authors: Francisco J B
authors: FJ
authors: Mendonça Junior
authors: Carlos A
authors: CA
authors: de Simone