Cobalt phthalocyanine conjugated SBA-15 mesoporous silica via the Ugi four-component reaction: A potential heterogeneous catalytic nanocomposite for CO2 fixation reaction

Owing to the porosity, high hydrothermal and mechanical stability of SBA-15, this type of silica mesoporous has attracted significant attention from many researchers for catalytic systems design. Accordingly, SBA-15 was utilized in this work as eco-friendly support to synthesize an effective heterogeneous catalytic nanocomposite based on the conjugation or immobilization of metalophthalocyanines (MPcs). For this purpose, initially, SBA-15 was modified by (3-aminopropyl)triethoxysilane (APTES) as an amination agent to produce SBA-15-NH2 and then participated in a straightforward one-pot Ugi four-component reaction (Ugi-4CR) of cyclohexyl isocyanide, benzaldehyde, and cobalt (II) phthalocyanine tetracarboxylic acid (Co-PcTCA) as an acid component. Afterward, the catalytic activity of the cobalt (II) phthalocyanine immobilized via SBA-15-NH2 (Co-PcTCA/SBA-15-N) was examined in the CO2 fixation reaction for the preparation of cyclic carbonates in water as a green solvent. Interestingly, catalytic experiments revealed that SBA-15 as a porose support could considerably ameliorate the catalytical properties of the Co-PcTCA regarding the CO2 fixation reaction via high CO2 adsorbent capacity in the shortest reaction time.