Anthracene–BODIPY Cassettes: Syntheses and Energy Transfer

Abstract

Compounds based on the 4,4-difluoro-1,3,5,7-tetramethyl-4-bora-3a,4a-diaza-s-indacene (BODIPY) framework are excellent fluorescent markers. When BODIPY dyes of this type are conjugated to functionalities that absorb at relatively short wavelengths, those functionalities can, in some molecules, transmit the absorbed energy to the BODIPY which then fluoresces. In such cases the BODIPY fragment acts as an acceptor while the other group serves as a donor. Energy transfer efficiencies in such donor-acceptor cassette systems must vary with the relative orientation of the two components, and with the structure of the linkers that attach them. This study was designed to probe these issues for the special case in which the linkers between the donor and acceptor fragments are conjugated. To do this, the cassettes 3-10 were prepared. Electrochemical studies were performed to provide insight into the degree of donor-acceptor conjugation in these systems. X-ray Crystallographic studies on single crystals of compounds 7 and 9 revealed the favored conformations of the donor and acceptor fragments in the solid state. Absorption, fluorescence, and time-resolved fluorescence spectra of the compounds were recorded, and quantum yields for the cassettes excited at the donor lambda(max) were measured. Fluorescence steady-state anisotropy data were determined for cassettes 3 and 9 to provide information about the mutual direction of the transition dipole moments.

Strongly Emissive and Photostable Four‐Coordinate Organoboron N,C Chelates and Their Use in Fluorescence Microscopy

“…These shortcomings normally require alternative photophysical designs such as antenna-Bodipy energy transfer dyads. [44][45][46][47] …”

Excited-State Dynamics of Donor−Acceptor Bridged Systems Containing a Boron−Dipyrromethene Chromophore: Interplay between Charge Separation and Reorientational Motion

“…36 BODIPY chromophores have also been used in synthetic light-harvesting antenna, 37 photonic wires, 38 optoelectronic gates, 39 and other energy donor-acceptor systems. [40][41][42] Photoinduced ET reactions with BODIPY dyes have already been reported. Tonimura et al have shown that the fluorescence of BODIPY dyes can be efficiently quenched by nucleotide bases.…”

First Evidence for a Uniquely Spin‐Polarized Quartet Photoexcited State of a π‐Conjugated Spin System Generated via the Ion‐Pair State

“…The bodipy moiety is well known as an efficient through-bond energy acceptor for anthracene. [10] Herein, we present the first evidence of a uniquely spinpolarized quartet photoexcited state generated by a novel spin-polarization mechanism via the ion-pair state. Compound 1 was synthesized according to Scheme 1.…”

“…As a model compound, we designed 1, in which a 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (bodipy) acceptor moiety (A), [10] is covalently linked through an anthracene moiety, as a donor (D) to the verdazyl p radical (R). p-Conjugated system 2 (D-R) has a quartet (S = 3/2) photoexcited state.…”

“…The oxidation potential of phenylanthracene is slightly higher than that of component A. [10] Thus, there is no charge transfer (CT) character in the ground state. However, if one-electron photoexcitation from the highest occupied molecular orbital (HOMO) of A is carried out, the orbital becomes lower in energy because the on-site Coulomb repulsion is removed.…”