Intercalation d'ions alkylammonium et d'alkylamines a longues chaines dans les gels de V2O5

Abstract CnH2n+1N+(CH3)3 ions and CnH2n+1NH2 amines with n ranging from 1 to 18 have been intercalated into the lamellar structure of V2O5 gels. Alkyl chain orientation in the interfoliar space has been deduced from the basal d-spacing evolution with the chain length : the chains are parallel, then tilted and finally perpendicular to the host lamellae as the chain length increases. Their monolayer disposition is also demonstrated. The large adaptability of the host structure proceeding from its gel state, leads to fast reaction at room temperature, especially with small polar heads such as -NH2 (less than an hour). Contrary to usual intercalates, due to the gel state, only a mean composition can be defined. It has been found to correspond to 0.3–0.4 intercalated species per V2O5 : this is in good agreement with the upper limit (0.5) deduced from sterical considerations based upon a full filling of the interfoliar space. Thermal decomposition of alkyl chains restricts the stability of these intercalates to 160°C. More likely of the cationic exchange type with trimethylammonium ions, intercalation mechanism appears more complex with amines, involving probably also a host-guest charge transfer.