Interplay of Dual-Proton Transfer Relay to Achieve Full-Color Panel Luminescence in Excited-State Intramolecular Proton Transfer (ESIPT) Fluorophores

Abstract

A new design was applied for the facile synthesis of pure organic photoluminescent molecules with dual excited-state intramolecular proton transfer (ESIPT) sites. In this novel class of emitters, full-color panel emission from blue, green, and yellow to red, including white light, can be achieved in different solvents as modulated by the enol−keto(1st)−keto(2nd) tautomer emissions. A comprehensive transient photophysical study verifies that keto(1st) and keto(2nd) have a precursor (<0.8 ps)− successor (∼20 ps)-relayed absorbance relationship, and then a fast equilibrium between the two is established, resulting in dual emissions in the nanosecond scale (∼1900 ps). Through the research on copper ions' selective PL response, the dual-ESIPT mechanism was further verified; in addition, the study of solid-state PL changes upon the stimulus of organic vapor manifests the potential application sensitivity of the molecules as dual-ESIPT sensors. Theoretical results including reaction potential energy surface analyses manifest the fact that dual-proton transfer goes along a sequential route with a smaller energy barrier, firmly supporting the experimental results. An intrinsic system that undergoes intramolecular double proton relayed transfer is thus established for the achievement of much broadened optical responses and full-color display, providing reference for the design and application of advanced dual-ESIPT optical materials.

Regulated stepwise ESDPT mechanism associated with chalcogen substitutions in BDIBD derivatives

“…57–59 By way of comparison, herein, we emphasize that the theoretical level of TD-DFT/D3-B3LYP/TZVP and IEFPCM solvent models can reproduce the peak of the absorption spectrum of BDIBD experimentally ( i.e. , theoretical 406.43 nm is consistent with experimental ∼400 nm 49 ).…”

“…55,56 Especially, it is worth mentioning that we further used a range-separated hybrid functional (i.e., CAM-B3LYP) to investigate the photoinduced vertical excitation behaviors for BDIBD-O, BDIBD-S, and BDIBD-Se, and the corresponding results further verified the correctness and rationality of the Grimme's D3 calculation of the excited states. The acetonitrile solvent mentioned in previous research was employed exclusively throughout all simulations, 49 utilizing the IEFPCM approach. [57][58][59] By way of comparison, herein, we emphasize that the theoretical level of TD-DFT/D3-B3LYP/TZVP and IEFPCM solvent models can reproduce the peak of the absorption spectrum of BDIBD experimentally (i.e., theoretical 406.43 nm is consistent with experimental B400 nm 49 ).…”

“…A novel full-color panel luminescence fluorophore, (2,5-bis(4,5-diphenyl-1 H -imidazol-2-yl)benzene-1,4-diol) (BDIBD) and its related derivatives have been reported by Yi and coworkers recently. 49 Particularly, by means of ESDPT behaviors in different solvents, the full-color panel fluorescence could be found, which provides a reference for further design and develop novel organic optical materials showing ESDPT properties. Because BDIBD derivatives have such excellent properties in different solvents, they may also have important potential applications for oxygen-hydroxybenzoate-substituted BDIBD compounds.…”

Impact of Polymer Matrix on Polymer Mechanochromism from Excited State Intramolecular Proton Transfer†

“…[ 25‐29 ] As we know, solvent polarity and pH value significantly influence ESIPT reactions in solution. [ 30‐33 ] In addition, the polymer matrix plays another key role in ESIPT reactions due to strong interactions between electron‐withdrawing groups of polymers and active hydrogen atoms of ESIPT molecules. [ 34‐37 ] When ESIPT molecules are linked into the polymer chains, intermolecular hydrogen bonds are formed between branches of the polymer network and ESIPT molecules.…”

Influence of Solvents and Halogenation on ESIPT of Benzimidazole Derivatives for Designing Turn-on Fluorescence Probes

“…Intramolecular proton transfer (IPT) is an ultrafast reaction of importance in several types of organic and biological molecules mainly because of its practical applications. − In general, the IPT mechanism appears to be simple, although it cannot always be easily observed spectroscopically . However, IPT may occur in excited states (ES) leading to the so-called ESIPT process.…”