Cover Picture: Synthesis, Spectroscopy, Crystal Structure Determination, and Quantum Chemical Calculations of BODIPY Dyes with Increasing Conformational Restriction and Concomitant Red-Shifted Visible Absorption and Fluorescence Spectra (Chem. Asian J. 9/2010)
Written by Volker Leen on September 3, 2010 – 5:00 am -Two BODIPY dyes with increasingly rigid conformations were synthesized from the conformationally unconstrained 3,5-di-(2-bromophenoxy)-4,4-difluoro-8-(4-methylphenyl)-4-bora-3a,4a-diaza-s-indacene through palladium-catalyzed intramolecular benzofuran formation. In their Full Paper on page 2016 ff., W. Qin, W. Dehaen et al. report how restricted bond rotation of the phenoxy fragments led to more-intense absorption and fluorescence signals at longer wavelengths relative to the unconstrained dye. X-ray diffraction analysis showed progressively more-extended planarity of the chromophore with increasing conformational restriction. These conclusions were confirmed by quantum chemical calculations of the lowest electronic excitations.
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