(A) Reaction path for caffeine-modified carbon nitride materials from cyanuric acid-melamine supramolecular complexes. Adapted with permission from [98]. Copyright 2015, Wiley-VCH. (B) The formation process of C-doped hollow spherical C₃N₄. Adapted with permission from [96]. Copyright 2017, American Chemical Society. (C) Graphic representation of the CMB-x% supramolecular complex. Adapted with permission from [100]. Copyright 2014, American Chemical Society. (D) Reaction path for the modified-C₃N₄ materials from MCA and MA-phO supramolecular complexes. Adapted with permission from [101]. Copyright 2020, Elsevier. (E) Hydrogen-bonded supramolecular C-M-Mp complex and the proposed carbon nitride structure after calcination. Adapted with permission from [102]. Copyright 2014, American Chemical Society. (F) Carbon nitride (CM and CMR-CN) synthesis at 550°C from hydrogen-bonded supramolecular complexes as starting reactants. Adapted with permission from [103]. Copyright 2020, Wiley-VCH.