Single molecular precursors for C_xN_y materials- Blending of carbon and nitrogen beyond g-C₃N₄

Carbon nitride is considered as one of the oldest carbon-based material but a little was known about the structure and properties until the beginning of 21st century. The extensive synthetic and structural validation has changed the course of the journey of this wonder material. Presently, this material has found its application in physics, chemistry and biology. The most stable composition with carbon and nitrogen in graphitic carbon nitride (g-C₃N₄) is C:N = 0.75 where the unique attraction is the content of nitrogen and its relationship to the optical and semiconducting properties. Current investigations are in support that the C:N stoichiometry can be varied which plays a major role to control the semiconducting properties of the resulting carbon nitrides in C_xN_y (x,y: number of carbon and nitrogen). A wide range of C:N materials starting from single molecular precursors has extended the boundaries of carbon nitrides beyond C:N = 0.75 and has brought these nitrogenous carbons to life again. These C_xN_y materials can be produced with varying nitrogen content for favorable energy related and other applications. This review will discuss the synthesis of various carbon nitrides (C_xN_y) starting from single molecular precursors and their intrinsic catalytic and photocatalytic features along with the problems and wide opportunities for the benefit of researchers.