Hydrogen bond driven supramolecular assemblies during hybrid mesoporous silica films structuration

Understanding the molecular architecture of hybrid mesoporous materials remains a challenge due to the complexity of weak molecular interactions that govern the formation of the hybrid interface and the distribution of organic moieties. In this study, we employed infrared spectroscopy to systematically investigate the architecture of hybrid interfaces in thin mesoporous films functionalized in situ with ureidopropyl (UP) groups. Our IR spectral analysis revealed the formation of stable ureido-silanol and ureido-ureido hydrogen bonds during the film structuration. Notably, these hydrogen bonds remained intact despite template extraction, variations in UP concentration, or the introduction of additional probes, indicating their exceptional stability. Only through post-functionalization were these hydrogen bond assemblies disrupted. Furthermore, we conducted a comparative study between UP-based materials and previously reported films derived from phenylureido (PhU) precursor bearing a terminal aromatic ring. This comparison highlighted the influence of precursor size and its affinity for different micellar regions on the mesostructure and molecular organization of the materials. Additionally, the synthesis of films from bi-substituted ureido-based precursors underscored the crucial role of precursor structure in determining the architecture of hydrogen bonds within mesoporous hybrids. Finally, we demonstrated that dual-functionality probes, coupling ureido groups with chromophores, serve as promising tools for characterizing hybrid materials using both infrared and fluorescence spectroscopy.