PACKING MODES ANALYSIS IN 3,4,5-TRIMETHOXY N-(METHOXY MONOSUBSTITUED SALICYLIDENE) ANILINES. J. Estienne and C. Kodjo LSDM, Université de Provence, Centre de Saint-Jérôme,Case 542, av. escadrille Normandie-Niemen, F- 13397 Marseille Cedex 20

Structural investigation of the anils of salicylaldehyde, known for their thermochromic and/or photochromic properties, forms part of our study on the interplay in organic solid state between crystal forces and molecular conformation. Systematically varying a substituent position, we are carrying out an investigation of the nature of stacking interactions which involve a subtle and complicated interplay between van der Waals forces, dipole-dipole interactions, intermolecular hydrogen bonding and [[pi]] - [[pi]] interactions of aromatic rings. We report the structures and the packing analysis of four N-(Methoxysalicylidene)-3,4,5-trimethoxyanilines

(I) which differ only by the position of the methoxy group at the vanillidene ring.