Quantitative Design of Bright Fluorophores and AIEgens by the Accurate Prediction of Twisted Intramolecular Charge Transfer (TICT)

Abstract

Inhibition of TICT can significantly increase the brightness of fluorescent materials. Accurate prediction of TICT is thus critical for the quantitative design of high‐performance fluorophores and AIEgens. TICT of 14 types of popular organic fluorophores were modeled with time‐dependent density functional theory (TD‐DFT). A reliable and generalizable computational approach for modeling TICT formations was established. To demonstrate the prediction power of our approach, we quantitatively designed a boron dipyrromethene (BODIPY)‐based AIEgen which exhibits (almost) barrierless TICT rotations in monomers. Subsequent experiments validated our molecular design and showed that the aggregation of this compound turns on bright emissions with ca. 27‐fold fluorescence enhancement, as TICT formation is inhibited in molecular aggregates.

An Ester‐Substituted Semiconducting Polymer with Efficient Nonradiative Decay Enhances NIR‐II Photoacoustic Performance for Monitoring of Tumor Growth

“…Because the strongest electron‐withdrawing ability of TQE monomer can intensify the intramolecular charge transfer property, BDT‐TQE SP shows bathochromic and broad absorption covering NIR‐I to NIR‐II regions. Furthermore, upon excitation at 808 nm, BDT‐TQE SP emits with the longest wavelength (1523 nm) but the lowest intensity in comparison with BDT‐TQP (1275 nm) and BDT‐TQT (1289 nm) SPs at the same concentration, attributed to its strong TICT feature, [29] which is consistent with the theoretical results (vide supra). We further plotted the change of Stokes shift to Δ f value for the SPs according to the Lippert–Mataga relationship as the following equation, [30] …”

“…TheUV-vis-NIR absorption and photoluminescence (PL) spectra of BDT-TQP,B DT-TQT and BDT-TQE SPs in THF at ac oncentration of 100 mgmL À1 are shown in Figures 2a,b. Thea bsorption maxima are 897, 905 and 1109 nm for BDT-TQP,B DT-TQT and BDT-TQE SPs,r espectively.B ecause the strongest electron-withdrawing ability of TQE monomer can intensify the intramolecular charge transfer property, BDT-TQE SP shows bathochromic and broad absorption covering NIR-I to NIR-II regions.F urthermore,u pon excitation at 808 nm, BDT-TQE SP emits with the longest wavelength (1523 nm) but the lowest intensity in comparison with BDT-TQP (1275 nm) and BDT-TQT (1289 nm) SPs at the same concentration, attributed to its strong TICT feature, [29] which is consistent with the theoretical results (vide supra). We further plotted the change of Stokes shift to Df value for the SPs according to the Lippert-Mataga relationship as the following equation, [30]…”

An Ester‐Substituted Semiconducting Polymer with Efficient Nonradiative Decay Enhances NIR‐II Photoacoustic Performance for Monitoring of Tumor Growth

“…Because the strongest electron‐withdrawing ability of TQE monomer can intensify the intramolecular charge transfer property, BDT‐TQE SP shows bathochromic and broad absorption covering NIR‐I to NIR‐II regions. Furthermore, upon excitation at 808 nm, BDT‐TQE SP emits with the longest wavelength (1523 nm) but the lowest intensity in comparison with BDT‐TQP (1275 nm) and BDT‐TQT (1289 nm) SPs at the same concentration, attributed to its strong TICT feature, [29] which is consistent with the theoretical results (vide supra). We further plotted the change of Stokes shift to Δ f value for the SPs according to the Lippert–Mataga relationship as the following equation, [30] …”

A Systematic Study of Coumarin–Tetrazine Light‐Up Probes for Bioorthogonal Fluorescence Imaging

“…In a very recent computational study, the importance of the solvation model for accurate computations of TICT forms has been pointed out . Therefore, we re‐optimized the tentative TICT structures with a SMD model used for implicit water solvation.…”