Phosphine-based push-pull AIE fluorophores: Synthesis, photophysical properties, and TD-DFT studies

• Published in: Dyes and pigments Vol. 193; no. 1; p. 109485
• Main Authors: Rémond, Maxime, Colinet, Pauline, Jeanneau, Erwan, Le Bahers, Tangui, Andraud, Chantal, Bretonnière, Yann
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.09.2021; Elsevier
• Subjects: AIE; Chemical Sciences; DFT; Large Stokes shift; or physical chemistry; Organic chemistry; Phosphine based dyes; Push-pull dyes; Theoretical and; Large Stokes shift; Phosphine based dyes; Push-pull dyes; DFT; AIE
• ISSN: 0143-7208; 1873-3743
• DOI: 10.1016/j.dyepig.2021.109485

Herein, we report the design and characterization of a novel series of four push-pull fluorophores using diphenylphosphino as an electron-donating terminal group (P-chromophores). The spectroscopic properties in solution, the aggregation-induced emission (AIE) properties, as well as the emission properties in the solid state were studied and compared with those of the diphenylamino-analogues (N-chromophores). Comparative analysis of the crystalline structures coupled with density functional theory calculations revealed that the diphenylphosphino group adopts a pyramidal geometry, whereas a trigonal planar configuration around the N-center is observed for the diphenylamino group. Consequently, the phosphorous lone pair is localized on the upper side of the average chromophore plan and considerable geometrical change of the P-center can occur between the ground state and the first excited state, explaining the much larger Stokes shift observed (10 000 cm−1) for the P-chromophores compared to the N-analogues. [Display omitted] •Push-pull dyes with a λ3σ3 diphenylphosphino electro-donor group were studied (P-dyes).•The weaker electro-donor character of P compared to N cause a blue-shift in the optical properties.•P-dyes showed solid-state emission with much larger Stokes shift than N-dyes.•P-centers adopt a trigonal pyramidal geometry whereas the N-centers are strictly trigonal planar.•The larger Stokes shift is due to bigger geometrical change of the donor P-atom between ground and first excited state.