Preparation of choline sulfate ionic liquid supported on porous graphitic carbon nitride nanosheets by simple surface modification for enhanced catalytic properties

Supported ionic liquids (SILs) have attracted rising interest and the subject of active research in the last decades due to the diversified range of applications and yet reports on ILs is still rapidly increasing. This work reports a choline sulfate ionic liquid supported on fascinating and highly stable porous graphitic carbon nitride (g-C3N4) nanosheets as an inexpensive and an environmentally friendly reusable ionic catalyst in organic synthesis typically requiring a harmful organic solvent and highly toxic acids. g-C3N4@SO3Ch was prepared by mixing sulfonic acid functionalized graphitic carbon nitride nanosheets (g-C3N4@SO3H) with choline hydroxide or via a novel approach. The introduction of a choline sulfate could significantly enlarge specific surface areas with rich reaction sites and suppressed the recombination of sheets. This work provides a new way to improve the chemical property of g-C3N4 along with the recyclability of the ionic liquid. g-C3N4@SO3Ch (IL/g-C3N4) offers an effective, reusable, inexpensive, environmentally friendly and low-cost catalyst for the synthesis of 3,4-dihydropyrimidin-2 (1H)-ones, 2,3-dihydroquinazolin-4 (1H)-ones and bisindolylmethanes in good to excellent yields. The prepared catalyst synthesized compounds were well characterized by different techniques such as FT-IR, XRD, SEM, EDX and TGA. [Display omitted] •Highly active ionic mesoporous graphitic carbon nitrides were prepared.•Enhancement of surface properties of carbon nitride by the choline sulfate ionic liquid.•This approach appears as a promising route to prepare highly ionic g-C3N4.•Superior catalytic activities to other mesoporous materials.•The IL-C3N4 composite was recycled several times without loss in its activity.