Crystal structures of ethyl 6-(4-methylphenyl)-4-oxo-4H-chromene-2-carboxylate and ethyl 6-(4-fluorophenyl)-4-oxo-4H-chromene-2-carboxylate

• Autor(a) principal: Gomes, Ligia R.
• Data de Publicação: 2016
• Outros Autores: Low, John Nicolson, Fernandes, Carlos, Gaspar, Alexandra, Borges, Fernanda
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10284/8170
• topic: Crystal structure; Drug design; Chromone; Conformation supra­molecular structure

The crystal structures of two chromone derivatives, viz. ethyl 6-(4-methyl­phen­yl)-4-oxo-4H-chromene-2-carboxyl­ate, C19H16O4, (1), and ethyl 6-(4-fluoro­phen­yl)-4-oxo-4H-chromene-2-carboxyl­ate C18H13FO4, (2), have been determined: (1) crystallizes with two mol­ecules in the asymmetric unit. A comparison of the dihedral angles beween the mean planes of the central chromone core with those of the substituents, an ethyl ester moiety at the 2-position and a para-substituted phenyl ring at the 6-position shows that each mol­ecule differs significantly from the others, even the two independent mol­ecules (a and b) of (1). In all three mol­ecules, the carbonyl groups of the chromone and the carboxyl­ate are trans-related. The supra­molecular structure of (1) involves only weak C-H...[pi] inter­actions between H atoms of the substituent phenyl group and the phenyl group, which link mol­ecules into a chain of alternating mol­ecules a and b, and weak [pi]-[pi] stacking inter­actions between the chromone units. The packing in (2) involves C-H...O inter­actions, which form a network of two inter­secting ladders involving the carbonyl atom of the carboxyl­ate group as the acceptor for H atoms at the 7-position of the chromone ring and from an ortho-H atom of the exocyclic benzene ring. The carbonyl atom of the chromone acts as an acceptor from a meta-H atom of the exocyclic benzene ring. [pi]-[pi] inter­actions stack the mol­ecules by unit translation along the a axis.