Twisted Intramolecular Charge Transfer and Aggregation-Induced Emission of BODIPY Derivatives

Abstract

Boron dipyrromethene (BODIPY) derivatives 1 and 2 consisting of donor and acceptor units with dual photoresponses to solvent polarity and luminogen aggregation are developed through taking advantage of twisted intramolecular charge transfer (TICT) and aggregation-induced emission (AIE) processes. In nonpolar solvents, the locally excited (LE) states of the BODIPY luminogens emit intense green lights. Increasing solvent polarity brings the luminogens from the LE state to the TICT state, causing a large bathochromic shift in the emission color but a dramatic decrease in the emission efficiency. The red emission is greatly boosted by aggregate formation or AIE effect: addition of large amounts of water into the solutions of 1 and 2 in the polar solvents causes the luminogens to aggregate supramolecularly and to emit efficiently. The emission can be enhanced by increasing solvent viscosity and decreasing solution temperature, indicating that the AIE effect is caused by the restriction of the intramolecular rotations in the aggregates of the luminogens.

Design and synthesis of theranostic antibiotic nanodrugs that display enhanced antibacterial activity and luminescence

“…2D). These observations are consistent with many other AIE-active luminogens having donor-acceptor structures (21,22,37,(39)(40)(41), where the aggregation hampers the intramolecular motion between the donor and the acceptor, hence leading to enhanced fluorescent emission as well as a blue shift in the emission peak (15). Spherical nanoaggregates were observed at high water content (≥99 vol %) (Fig.…”

“…The red shift and decrease in emission with the increase of solvent polarity (SI Appendix, Figs. S1 and S2) is indicative of a twisted intramolecular charge-transfer process upon photoexcitation from the donor (piperazinyl ring) to the acceptor (fluoroquinolone ring) (34,35), a process that is stabilized and promoted by polar solvents, however, susceptible to nonradiative quenching (36)(37)(38).…”

Vapochromic features of new luminogens based on julolidine-containing styrene copolymers

“…A similar behaviour was already known in literature for FMR-AIEgens. [120][121][122] Physical and optical properties of the mixtures are resumed in Table 3.1. In order to evaluate the effect of medium viscosity on the fluorophore emission, solutions of JCAEM in methanol/glycerol mixtures were prepared and analysed.…”

Self-Assembly of Bodipy-Derived Extended π-Systems

“…8184 The Bodipy derivative 32 appended with a triphenylamine moiety (Figure 15a) exhibited an absorption peak around 515 nm due to the π-π* transition in non-polar solvent and the absorption peak showed a blue-shift upon increasing the solvent polarity. 81 Upon excitation around 500 nm, the molecule 32 exhibited a green emission in n-hexane, yellow in toluene and red in polar solvent such as THF (Figure 15b, i). In highly polar solvents such as methanol, ethanol and acetonitrile, the emission of 32 was shifted to NIR region with a decrease in the intensity.…”