ATRP Initiators Based on Proton Transfer Benzazole Dyes: Solid-State Photoactive Polymer with Very Large Stokes Shift
Jônatas Faleiro Berbigier, Luís Gustavo Teixeira Alves Duarte, Matheus Fialho Zawacki, Bruno Bercini de Araújo, Cristtofer de Moura Santos, Teresa Dib Zambón Atvars, Paulo Fernando Bruno Gonçalves, César Liberato Petzhold, Fabiano Severo Rodembusch
Abstract
This work presents the synthesis, photophysical characterization, and application of ATRP polymerization initiators to produce photoactive solid-state fluorescent polystyrene-based polymers. These compounds present absorption in the UV region (∼340 nm) and emission in the blue-green regions with large Stokes shift (∼10 000 cm–1) due to a proton transfer process in the excited state (ESIPT). Theoretical calculations at TD-DFT level of theory with the CAM-B3LYP functional were also performed in order to study the geometry and charge distribution of these compounds in their ground and excited electronic states. In the calculations, the cc-pVDZ basis set was used to geometry optimization in S0 and S1 states and jun-cc-pVTZ basis set was used to describe the excited states. The results show an absorption maxima and emission in good agreement with the experimental values. As a proof-of-concept, ultraviolet absorbing and photoactive polymers based on polystyrene were successfully produced by ATRP polymerization applying the synthesized dye initiators. Moreover, these initiators allowed an intense fluorescence emission in the solid state with large Stokes shift; improved parameters for the synthesis, polymerization, and polydispersity if compared to already reported ESIPT initiator, as well as higher polymer photostability if compared to the pristine polystyrene.