title: Acidic Condensation of BODIPYs with Aldehydes: A Quick and Versatile Route to Alkenyl-BODIPYs and C(sp(3) )-Connected DYEmers.
abstract: The condensation of aldehydes with BODIPY (boron dipyrrin) luminophores was investigated. Formaldehyde can be used to connect two BODIPYs at each of the three pyrrolic C positions (α-, β-, and β'-positions) in a quick and highly selective manner, yielding new DYEmers (di- and oligomeric BODIPY derivatives) with varied photophysical properties. Benzaldehydes form DYEmers only at the β- and the β'-positions. For aliphatic aldehydes the DYEmer formation competes with the elimination of water from a proposed alcohol intermediate, leading to the formation of α- and β-alkenyl-BODIPYs. 2-Phenylacetaldehyde and similar precursors exclusively yield elimination products. These acid-mediated transformations are valuable alternatives to the well-established, base-promoted Knoevenagel condensation protocol that is typically employed in the preparation of BODIPYs with near infrared (NIR)-shifted absorptions.
authors.affiliation: Institute for Inorganic and Analytical Chemistry, Technical University Braunschweig, Hagenring 30, 38106, Braunschweig, Germany.
authors.forename: Johannes
authors.initials: J
authors.lastname: Ahrens
authors.affiliation: Institute for Inorganic and Analytical Chemistry, Technical University Braunschweig, Hagenring 30, 38106, Braunschweig, Germany.
authors.forename: Birte
authors.initials: B
authors.lastname: Cordes
authors.affiliation: Institute for Inorganic and Analytical Chemistry, Technical University Braunschweig, Hagenring 30, 38106, Braunschweig, Germany.
authors.forename: Richard
authors.initials: R
authors.lastname: Wicht
authors.affiliation: Institute for Inorganic and Analytical Chemistry, Technical University Braunschweig, Hagenring 30, 38106, Braunschweig, Germany.
authors.forename: Benedikt
authors.initials: B
authors.lastname: Wolfram
authors.affiliation: Institute for Inorganic and Analytical Chemistry, Technical University Braunschweig, Hagenring 30, 38106, Braunschweig, Germany. m.broering@tu-bs.de.
authors.forename: Martin
authors.identifier: http://orcid.org/0000-0001-6807-6579
authors.initials: M
authors.lastname: Bröring
keywords: BODIPY; DYEmers; condensation; dyes/pigments; synthetic methods