Imprinting With Phenyl Group Interactions: A Case Study of the Hybrid Sol-Gel Encapsulation of the Complex {Na[Ph2P(O)-CH2-P(O)Ph2]3}+

The sodium complex cation, {Na[Ph2P(O)-CH2-P(O)Ph-2](3)}(+), is used as a guest species in acid-catalyzed aqueous sol gel processes of tetraethoxysilane and phenyltriethoxysilane. Raman spectroscopy in combination with band assignments from DFT calculations, solid-state NMR, and thermal analyses are applied to study the structural integrity of the sodium complex and to characterize the structural properties of the sol gel materials. The sodium complex is decomposed at a synthesis pH value of 1, whereas it is encapsulated intact at pH = 4. Calcination removes the complex, and micropores are observed. Phenyl group interactions between the complex surface and the phenyl-functionalized hybrid gel are suggested to take place in the encapsulation process. The spherically shaped sodium complex serves as a model compound for surface interactions between aromatic groups during the genesis of an encapsulated sol gel hybrid material, and it can be regarded as a soft complex, whose structural stability is of the same order as the interaction energy with its environment.