Structure-Directing Effect of (S)-(-)-N-Benzylpyrrolidine-2-methanol and Benzylpyrrolidine in the Synthesis of STA-1: A New Computational Model for Structure Direction of Nanoporous Systems.
3447 - 3457.
We propose a new computational model to study structure direction in nanoporous materials that takes into account the stability of the guest species in solution as well as the possibility of occluding solvent molecules in the nanopores. The model is applied to study the structure directing effect of (S)-(-)-N-benzylpyrrolidine-2-methanol (BPM) and benzylpyrrolidine (BP) in the synthesis of the nanoporous STA-1 material (SAO framework type), and compare results with experimental characterization. Despite the fact that up to 8 BP or BPM molecules can be loaded within the nanoporous framework, the relative stability of the SDA molecules in solution and the simultaneous incorporation of water limit the amount of organic content. The most stable arrangements correspond to the occlusion of 6 BPM or 5 BP molecules per SAO unit cell, accompanied respectively by 9 and 22 water molecules in order to complete space filling, leading to a cooperative structure-directing action between organic SDA and water molecules during crystallization. The organic molecules act as primary structure-directing agents, and the water molecules as secondary space-filling species whose role is to completely fill the void space of the pore system and provide further stabilization to the nanoporous framework. We demonstrate the necessity of including in the computational models the occlusion of water molecules as well as to account for the stability of SDA and water molecules in solution for realistically studying the structure-directing effect of organic molecules in the synthesis of hydrophilic aluminophosphate nanoporous frameworks. We therefore provide a useful computational tool for studying the occlusion of guest species in host-guest systems, an issue which is essential for controlling the potential applications of these materials.
|Title:||Structure-Directing Effect of (S)-(-)-N-Benzylpyrrolidine-2-methanol and Benzylpyrrolidine in the Synthesis of STA-1: A New Computational Model for Structure Direction of Nanoporous Systems|
|Keywords:||CRYSTALLINE MICROPOROUS ALUMINOPHOSPHATES, TETRAALKYLAMMONIUM SILICATE SOLUTIONS, MOLECULAR-DYNAMICS, ORGANIC-MOLECULES, AQUEOUS-SOLUTION, SIMULATIONS, STABILITY, CATALYSIS, AGENT, ZEOLITES|
|UCL classification:||UCL > School of BEAMS
UCL > School of BEAMS > Faculty of Maths and Physical Sciences
Archive Staff Only