Amine-functionalized hollow mesoporous nano-bowl with bulky acid-imprinted free space around base sites and DMF-annealed mesoporous channels as an efficient solid base catalyst

Abstract

Tailoring free spaces around catalytic sites and constructing inter-connected channels between them are highly attractive for achieving easy accessibility of reactants to catalytic sites. In this study, a strategy for constructing free space around base sites through molecular imprinting and interconnected channel between them by solvent annealing was developed to achieve high reactant accessibility. The as-fabricated nanobowls with particle sizes of 345 nm were efficient solid bases with fast mass transfer owing to the characteristic architectural features, such as a thin shell thickness (30 nm), free space around the base centered at 4.0 nm, mesoporous channels (5−50 nm), and a hollow interior. The influence of porosity on catalytic behavior was investigated using Knoevenagel condensations, and was found to promote various aromatic aldehydes to afford products at room temperature in 84–98 % yield within 2 h. Furthermore, the catalyst reused ten times was able to be restored to obtain original high catalytic activity.