Synthesis and characterisation of hybrid mesoporous materials with the 1,4-diazobutadiene ligand

Novel mesoporous MCM-41 type hybrid materials were synthesised by co-condensation of a “flexible” ligand derived from 1,4-diazobutadiene (1) and tetraethyl orthosilicate in three different ratios (0.027, 0.05, and 0.20) and in the presence of cetyltrimethylammonium bromide as templating agent. Surfactant extraction under mild conditions produced hybrid mesoporous materials with uniform mesoporous scale channels, large pore volumes, and high specific surface areas. These mesoporous organosilicas were characterised by powder X-ray diffraction, nitrogen gas adsorption, 13C and 29Si solid state NMR and thermogravimetric analysis. Results from DFT calculations were used for discussing NMR and IR experimental data. The organosilica materials with lower content of organic molecules present uniform 2D-hexagonal mesoporous arrays with pore diameter ranging from 2.0 to 4.0 nm and a surface area ranging from 693 to 803 m2/g. The introduction of a larger amount, such as 20%, of organic building block seems to decrease the order of the material and reduce the space available within the pore.