Novel microporous hypercross-linked conjugated quinonoid chromophores with broad light absorption and CO2 sorption characteristics

Abstract

We have discovered formation of hypercross-linked conjugated quinonoid chromophores (polymers) with broad light absorption characteristics during cross-linking of aromatic monomers, such as benzene, naphthalene, anthracene, phenanthrene and 1,3,5-trimethyl benzene with 1,3,5-trioxane in the presence of an FeCl₃ catalyst. The para or ortho –CH₂ groups that bridge aromatic monomers were dehydrogenated during polymerization to form the quinonoids. The quinonoid chromophores were confirmed by their DRS-UV Vis and FTIR spectra. We have also discovered similar such quinonoid chromophores in the hypercross-linked polymers of aromatic monomers, reported from 1970 onwards by different research groups. The polymers were synthesized by similar experiments with an FeCl₃ catalyst, and brown colored. As all the polymers bear low band gaps, they strongly absorb light covering the wavelength range of 1000 to 200 nm. Most of the hypercross-linked polymer matrices carry microporous spheres of about 1 to 5 μm diameter and showed 6–7% CO₂ sorption. The polymers with their low band gaps will inspire research on semiconductors, solar cell devices, UV stabilizers/absorbers and infrared absorbers/detectors, molecular sensors and academic study.