COMPUTER-SIMULATION STUDIES ON THE ROLE OF TEMPLATING ORGANIC-MOLECULES IN THE SYNTHESIS OF ZSM-5

We report here the structure and electronic properties of a few typical representative molecules from a family containing more than 50 templating organic molecules which lead to the synthesis of zeolite ZSM-5. Force-field calculations were utilised to study the structural and conformational properties, while semi-empirical MNDO calculations were adopted to study the electronic properties. The conformational flexibility and the charge-compensating function were brought out as common features of these organic molecules. Furthermore, the interaction of various organic molecules with a suitable cluster model for the ZSM-5 framework was studied by MNDO calculations. The orientation of the template organic molecules and the actual conformation of the template-framework complex are derived, based on the X-ray crystal structure reports and the MNDO energetics. The influence of the nature of the functional group and the alkyl group on the electronic interaction is studied systematically. It has been shown that quantum-chemical calculations could be successfully utilised for the generalised description of the importance of several complex interactions which are mutually present.