Synthesis of the Aluminophosphate ICP-1 by Self-Assembly of 1,3-Diphenylguanidine: Insights into Supramolecular Aggregation

Abstract

1,3-Diphenylguanidine (DPG) has distinguishable polar and apolar groups, aromatic rings that can self-assemble through π–π type interactions, and high conformational flexibility. These features make it a potential self-assembling structure-directing agent in the synthesis of hybrid host–guest aluminophosphates. Computational simulations show that the molecule has a strong tendency to self-assemble in aqueous solution. Large supramolecular organic aggregates are produced, with the hydrophobic aromatic rings located in the center of the aggregates, stabilized by π–π type interactions, and the hydrophilic guanidine groups on the external surface in close contact with water molecules. With this organic molecule, a new 1-D AlPO framework material (ICP-1) was formed. Its structure, characterized by a combination of single-crystal and powder diffraction techniques, consists of AlP2O8H chains connected to the polar groups of the organic DPG molecules through a complex H-bonding network. This material has an extremely high organic content, close to that of typical mesoporous materials. However, DPG molecules are part of the ICP-1 network, rather than guest molecules in the pores, so removal of DPG results in a collapse of the structure, limiting its potential applications. Nevertheless, this work demonstrates the potential of using self-assembling organic molecules for producing very open-framework materials.