| Autor: |
Bayer Kömüşdoğan E; Department of Chemistry, Middle East Technical University, 06800 Ankara, Turkey. tanyeli@metu.edu.tr., Batool S; Department of Chemistry, Middle East Technical University, 06800 Ankara, Turkey. tanyeli@metu.edu.tr., Şahin E; Department of Chemistry, Atatürk University, Erzurum, 25240, Turkey., Yildirim E; Department of Chemistry, Middle East Technical University, 06800 Ankara, Turkey. tanyeli@metu.edu.tr., Işık M; Department of Food Engineering, Bingöl University, Bingöl, 12000, Turkey. misik@bingol.edu.tr., Tanyeli C; Department of Chemistry, Middle East Technical University, 06800 Ankara, Turkey. tanyeli@metu.edu.tr. |
| Abstrakt: |
This work describes one-step syntheses of various stereogenic-at-boron fluorochromes (BOSPYR) via multicomponent reactions involving readily accessible boronic acids, salicylaldehydes, and 2-formylpyrrole hydrazones. The dyes absorb and emit in the visible region of the electromagnetic radiation, and are characterized by large Stokes shifts (2850-4930 cm -1 ) with weak fluorescence emissions ( Φ fl : 1.5-9.1%). Notably, the dimmed fluorescence of BOSPYRs recovers upon transition to viscous media (21-fold for 1a). The representative compound 1a exhibits clear Cotton effects with dissymmetry factors of ca . | g abs | ∼ 1.9 × 10 -3 in the visible region, indicating efficient asymmetry induction to the chromophore. The X-ray molecular structure of 1a shows that the chromophore deviates from planarity by 17.2°, which may contribute significantly to the inherent chirality of the fluorophore. A computational examination of excited states by time-dependent density functional theory (TD-DFT) identifies the emission mechanism as arising from a locally-excited (LE) state. |
