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

Ming Hui Chua, Taeyeon Kim, Zheng Long Lim, Tullimilli Y. Gopalakrishna, Yong Ni, Jianwei Xu, Dongho Kim, Jishan Wu

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11 Citations (Scopus)

Abstract

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. 1H 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.

Original languageEnglish
Pages (from-to)2232-2241
Number of pages10
JournalChemistry - A European Journal
Volume24
Issue number9
DOIs
Publication statusPublished - 2018 Feb 9

Bibliographical note

Funding Information:
The work in Singapore was financially supported by an A*STAR JCO grant (1431AFG100) and the MOE Tier 3 Programme (MOE2014-T3-1-004). The work at Yonsei University was supported by the National Research Foundation of Korea (NRF) through a grant funded by the South Korean government (MEST; no. 2016R1E1A1A01943379).

Publisher Copyright:
© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

All Science Journal Classification (ASJC) codes

  • Catalysis
  • Organic Chemistry

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