Enhanced non-linear optical properties of porphyrin-based polymers covalently functionalized with graphite phase carbon nitride

In our work, a flurry of original porphyrin-based polymers covalently functionalized g-C(3)N(4) nanohybrids were constructed and nominated as PPorx-g-C(3)N(4) (x = 1, 2 and 3) through click chemistry between porphyrin-based polymers with alkyne end-groups [(PPorx-C≡CH (x = 1, 2 and 3)] and azide-functionalized graphitic carbon nitride (g-C(3)N(4)-N(3)). Due to the photoinduced electron transfer (PET) between porphyrin-based polymers [PPorx (x = 1, 2 and 3)] group and graphite phase carbon nitride (g-C(3)N(4)) group in PPorx-g-C(3)N(4) nanohybrids, the PPorx-g-C(3)N(4) nanohybrids exhibited better non-linear optical (NLO) performance than the corresponding PPorx-C≡CH and g-C(3)N(4)-N(3). It found that the imaginary third-order susceptibility (Im [χ((3))]) value of the nanohybrids with different molecular weight (MW) of the pPorx group in the nanohybrids ranged from 2.5×10(3) to 7.0 × 10(3) g mol(−1) was disparate. Quite interestingly, the Im [χ((3))] value of the nanohybrid with a pPorx group’s MW of 4.2 × 10(3) g mol(−1) (PPor2-g-C(3)N(4)) was 1.47 × 10(–10) esu, which exhibited the best NLO performance in methyl methacrylate (MMA) of all nanohybrids. The PPorx-g-C(3)N(4) was dispersed in polymethyl methacrylate (PMMA) to prepare the composites PPorx-g-C(3)N(4)/PMMA since PMMA was widely used as an alternative to glass. PPor2-g-C(3)N(4)/PMMA showed the excellent NLO performance of all nanohybrids with the Im [χ((3))] value of 2.36 × 10(–10) esu, limiting threshold of 1.71 J/cm(2), minimum transmittance of 8% and dynamic range of 1.09 in PMMA, respectively. It suggested that PPorx-g-C(3)N(4) nanohybrids were potential outstanding NLO materials.