Influence of the in situ decomposition of ethylformamide on the gallophosphates crystallization

The in situ generation of the structure-directing agent is a new synthesis route developed in our laboratory since 1996. The alkylformamide molecules, used as main solvent, in our synthesis mixtures are unstable in acidic media and decompose at high temperature generating in situ the corresponding ethylamine molecules which act as structure-directing agents. In this paper, we report the influence of some synthesis parameters (temperature, heating time, etc.) on the in situ decomposition of ethylformamide. The influence on the nature of the synthesized products is also described and illustrated from the starting synthesis mixture of a 1-D gallophosphate named Mu-37. This compound, which is structurally related to two fluorogallophosphates reported in the literature, has the following chemical formula GaP2O7F[CH3CH2NH3]2 (Z = 4), and consists of one-dimensional anionic gallium diphosphate chains containing GaO4F2 units linked by diphosphate P2O7 ones, and charge-balanced by protonated ethylamine molecules. Mu-37 was also characterized by powder XRD, SEM, elemental and thermal analyses, and solid state NMR spectroscopy (13C, 31P MAS and 1H-31P CP MAS experiments).