Framework Functionalization of Periodic Mesoporous Organosilica with 1,2-bis[3-(triethoxysilylpropyl)ureido] cyclohexane Function via Basic Co-condensation Self-Assembly

The synthesized bis silylated long alkyl chain containing organosilicate precursor, 1,2-bis(3-(triethoxysilylpropyl)ureido)cyclohexane (BSPUCh) has been used as co-precursor with 1,2-bis (triethoxysilyl)ethane (BTSE) for the preparation of functional periodic mesoporous organosilicas (PMOs) via surfactant-mediated basic co-condensation self-assembly method. The various characterization techniques such as X-ray diffraction patterns (XRD), transmission electron microscope (TEM), N-2 adsorption-desorption isotherms (BET), FT-IR, and C-13 and Si-29 CPMAS NMR spectroscopies were used to characterize the resulting structure of functionalized PMO mesostructures. Results obtained from XRD, TEM, and BET analysis clearly showed that the structural and pore arrangement of the functionalized PMOs were found to be dependent on the used concentration of BSPUCh. The functional PMOs showed well ordered mesophases when BSPUCh concentration was <= 9 wt% in the initial mixtures, whereas higher concentration of the BSPUCh always produced disordered hierarchical mesostructures with bimodal pore size distributions. The incorporation of BSPUCh also reduces the surface area, pore volume, pore size, and pore wall thickness of the functionalized nanostructures, indicating that the BSPUCh is incorporated in the pore channels of the PMOs. The solid-state C-13 and Si-29 NMR spectra showed that the BSPUCh organosilicate with non-hydrolyzable bridging ligands propylureidocyclohexane has been successfully covalently linked in the framework of the resulting functional PMOs.