Bis(dioxaborine) Dyes with Variable π‐Bridges: Towards Two‐Photon Absorbing Fluorophores with Very High Brightness. Issue 12 (5th February 2018)

• Record Type: Journal Article
• Authors: Marín, Á. Moneo; Telo, João P.; Collado, Daniel; Nájera, Francisco; Pérez‐Inestrosa, Ezequiel; Pischel, Uwe
• Is Part Of: Chemistry. Volume 24:Issue 12(2018)
• Page Start: 2929
• Page End: 2935
• Publication Date: 2018-02-05
• Subjects: bis(dioxaborines) -- dyes -- fluorescence -- photophysics -- two-photon absorption; Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.201704544
• Languages: English
• ISSNs: 0947-6539

Abstract

Abstract: Bis(dioxaborine) dyes of the A‐π‐A format (A: acceptor, π: conjugated bridge) were prepared and photophysically characterized. The best performing dyes feature (a) visible‐light absorption (>400 nm), (b) high molar absorption coefficients (up to 70000 m −1 cm −1 ), (c) Stokes shifts in the range of ca. 2500–5800 cm −1, and (d) strong fluorescence emission with quantum yields of up to 0.74. This yields very bright‐emitting dyes for one‐photon excitation. However, the most intriguing feature of the dyes is their strong two‐photon absorption. This was achieved by means of increased π‐conjugation in the phenylene or phenylene‐thiophene bridges through the variation of the conjugation length and rigidity. This provided two‐photon absorption cross sections of up to 2800 GM (1 Goeppert‐Mayer (GM)=10 −50 cm 4 s photon −1 ). Considering the mentioned high fluorescence quantum yields, exceptionally bright‐emitting A‐π‐A two‐photon absorbing dyes with low molecular mass are obtained. Time‐dependent density‐functional theory calculations corroborated the experimental results. Abstract : Shine bright : Near‐infrared two‐photon excitation of bis(dioxaborines) with exceptional cross sections yields strong fluorescence. The rationally designed dyes with variable π‐conjugation belong to the brightest emitting two‐photon absorbers with acceptor‐π‐acceptor architecture known to date.