A new recyclable g-C3N4@PDMS heterogeneous catalyst has been developed as an efficient catalyst with an appreciable reactivity toward Knoevenagel condensation in the presence of crown ether (PTC). Here, a two-dimensional (2D) printed g-C3N4@PDMS heterogeneous catalyst opens the gate of possibility for high mechanical strength with the possibility of an appreciable recyclability. Various performed parameter studies clarify that g-C3N4 active sites exclusively enhance the cinnamic acid synthesis under mild reaction conditions. To explore the molecular mechanism of the condensation reaction over the heterogeneous catalyst surface, a systematic density functional theory-based computational study has been carried out. g-C3N4 material-based model substrate consisting of amine active sites has been considered for modeling the condensation reaction. The reaction energy profile for the condensation reaction between benzaldehyde and para-nitrotoluene on model substrate has been analyzed. The g-C3N4@PDMS catalyst is reused for several runs without loss in reaction rate, evidently due to the g-C3N4 active site being effectively implanted with highly resistant poly(dimethylsiloxane) (PDMS) layer. Recycled g-C3N4@PDMS heterogeneous 2D film characterization studies, viz., X-ray diffraction, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy, confirm that the active site and molecular structure are well preserved even after multiple reaction cycles. Various reactants were screened using the heterogeneous g-C3N4@PDMS catalyst, exhibiting an appreciable product yield (∼99%) at room temperature in a short reaction time of 30 min.
Bibliographical noteFunding Information:
The authors acknowledge Dr. Hani Gnayem for accomplishing the present research work. They thank Prof. Sarah Bergbreiter (Micro Robotics Lab, Carnegie Mellon University) for allowing them to use her lab facility. We would like to thank BARC computer center for providing the high performance parallel computing facilty. This research was partially supported by the Israel National Nanotechnology Initiative FTA project on functional coatings and printing.
© 2019 American Chemical Society.
- Knoevenagel condensation
- density functional theory (DFT)
- heterogenous catalyst