BODIPY-Based Antiaromatic Macrocycles: Facile Synthesis by Knoevenagel Condensation and Unusual Aggregation-Enhanced Two-Photon Absorption Properties.

Publisher: Wiley-VCH Country of Publication: Germany NLM ID: 9513783 Publication Model: Print-Electronic Cited Medium: Internet ISSN: 1521-3765 (Electronic) Linking ISSN: 09476539 NLM ISO Abbreviation: Chemistry Subsets: PubMed not MEDLINE

Original Publication: Weinheim, Germany : Wiley-VCH

Two stable boron dipyrromethene (BODIPY)-based antiaromatic macrocycles, Mc-Fur and Mc-Th, were synthesized through a one-pot Knoevenagel condensation reaction between a BODIPY precursor and furan-2,5-dicarboxaldehyde or thiophene-2,5-dicarboxaldehyde, respectively. ¹ H NMR spectroscopic characterization of the two macrocycles supported their highly antiaromatic character. The oxidation properties of the two macrocycles were studied through electron spin resonance spectroscopy and UV/Vis absorption spectrophotometry, which suggested the formation of a stable monoradical cation species on first oxidation followed by an aromatic dicationic species on subsequent oxidation. Both molecules have a nearly planar π-conjugated backbone and show a strong tendency to aggregate in solution due to efficient stacking of the antiaromatic macrocycles. Transient absorption and two-photon absorption (TPA) measurements in solution and aggregated states of the macrocycles revealed that aggregation resulted in large enhancement of TPA cross sections and increased excited-state lifetimes, in accordance with the decrease in the antiaromatic character in the aggregated state.
(© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Keywords: aggregation; antiaromaticity; macrocycles; synthesis design; two-photon absorption

Date Created: 20171209 Date Completed: 20180307 Latest Revision: 20180307

20250114

10.1002/chem.201705271

29218746