Linker engineering to regulate fluorescence of 1,3,5-tris(phenylacetylene)benzene-based covalent organic frameworks for white light-emitting diodes and information encryption and decryption

Luminescent covalent organic frameworks (LCOFs) is a promising luminescent material with huge potential for various applications because it can integrate various chromophores into its porous ordered structure. A facile and effective approach to edit LCOFs emission is very necessary but remains a challenge. Herein, a rigidity-flexibility combination strategy to edit the luminescence properties of LCOFs was proposed by using a flexible fluorescent 1,3,5-tris(phenylacetylene) benzene with propeller-like conformation as center skeleton and linkers with different rigidity and conjugation degree. Since the conjugated degree of LCOFs’ frameworks depended on conformation of propeller-like 1,3,5-tris(phenylacetylene)benzene skeleton, the emission wavelengths of 1,3,5-tris (phenylacetylene)benzene-based LCOFs could be edited by linkers to tune conjugated degree of the frameworks. These 1,3,5-tris(phenylacetylene)benzene-based LCOFs emitted blue, green, yellow, orange and red light depending on the conjugation degree caused by the effect of the linkers of melem, terephthalic dihydrazide, hydrazine hydrate and p-phenylenediamine on the conformation of central skeleton. Binary or ternary mixed 1,3,5-tris(phenylacetylene)benzene-based LCOFs were used for white emission, white light-emitting diodes and information encryption/decryption. The work provides a simple yet efficient method to systematically edit the emission behaviors of LCOFs by linker engineering.