Structure Directing Effect of (1S,2S)-2-Hydroxymethyl-1-benzyl-1-methylpyrrolidinium in the Synthesis of AlPO-5.
J PHYS CHEM C
8320 - 8327.
A pure diastereoisomer of a new chiral organic molecule with two asymmetric atoms, (1S, 2S)-2-hydroxymethyl-1-benzyl-1-methylpyrrolidinium, has been prepared and used as structure directing agent (SDA) for the crystallization of the one-dimensional AlPO-5 microporous aluminophosphate. Our main objective is to induce chiral supramolecular arrangements of the SDA molecules within the microporous structure. The SDA molecules can be arranged as monomers or dimers within the nanochannels of AlPO-5, the aggregation being driven by pi-pi type interactions between the aromatic rings. It has been found that increasing the crystallization time leads to a higher organic content (and lower water incorporation) together with a higher formation of dimers, which indicates that the incorporation of the organic molecules as dimers is thermodynamically favored. We also observe a partially reversible photoinduced rearrangement of the SDAs, the aggregation is enhanced by exciting the occluded monomers with the appropriate wavelength. A recently developed computational model has been applied to determine the stable loading of SDAs and water molecules, which has been found to be of 1.0 SDA and 7 water molecules per unit cell, with water forming stable 6-ring clusters between consecutive dimers, in good agreement with the experimental observations.
|Title:||Structure Directing Effect of (1S,2S)-2-Hydroxymethyl-1-benzyl-1-methylpyrrolidinium in the Synthesis of AlPO-5|
|Keywords:||MOLECULAR-SIEVE SYNTHESIS, CATION-PI-INTERACTION, ORGANIC-MOLECULES, MICROPOROUS ALUMINOPHOSPHATES, AFI STRUCTURE, ZEOLITES, SIMULATIONS, CATALYSTS, WATER, (S)-(-)-N-BENZYLPYRROLIDINE-2-METHANOL|
|UCL classification:||UCL > School of BEAMS > Faculty of Maths and Physical Sciences > Chemistry|
Archive Staff Only