Strength of London Dispersion Forces in Organic Structure Directing Agent-Zeolite Assemblies

Herein, we study the London dispersion forces between organic structure directing agents (OSDAs)-here tetraalkyl-ammonium or -phosphonium molecules-and silica zeolite frameworks (FWs). We demonstrate that the interaction energy for these dispersion forces is correlated to the number of H atoms in OSDAs, irrespective of the structures of OSDAs or FWs, and of variations in charges and thermal motions. All calculations considered-DFT-D3 and BOMD undertaken by us, and molecular mechanics from an accessible database-led to the same trend. The mean energy of these dispersion forces is ca. -2 kcal.mol^-1 per H for efficient H-O contacts.