TY - JOUR

T1 - Abnormal push-pull benzo[4,5]imidazo[1,2-a][1,2,3]triazolo[4,5-e]pyrimidine fluorophores in planarized intramolecular charge transfer (PLICT) state

T2 - Synthesis, photophysical studies and theoretical calculations

AU - Taniya, Olga S.

AU - Fedotov, Victor V.

AU - Novikov, Alexander S.

AU - Sadieva, Leila K.

AU - Krinochkin, Alexey P.

AU - Kovalev, Igor S.

AU - Kopchuk, Dmitry S.

AU - Zyryanov, Grigory V.

AU - Liu, Yuanli

AU - Ulomsky, Evgeny N.

AU - Rusinov, Vladimir L.

AU - Charushin, Valery N.

N1 - Funding Information: This work was supported by the Russian Science Foundation (# 21-13-00304 ) and Grants Council of the President of the Russian Federation ( NSh-1223.2022.1.3 ). This work was performed using « Uran » supercomputer of IMM UB RAS. This paper has been supported by the RUDN University Strategic Academic Leadership Program . Funding Information: This work was supported by the Russian Science Foundation (# 21-13-00304) and Grants Council of the President of the Russian Federation (NSh-1223.2022.1.3). This work was performed using « Uran » supercomputer of IMM UB RAS. This paper has been supported by the RUDN University Strategic Academic Leadership Program. Publisher Copyright: © 2022

PY - 2022/8/1

Y1 - 2022/8/1

N2 - The combination of excellent luminescence with high solvent polarity effect and aggregation induced emission (AIE) is an ideal combination for creating fluorophores/probes with high microenvironmental sensitivity. However, many push-pull chromophores of the D−A type in common intramolecular charge transfer (ICT) state with a significant solvatochromic effect and AIE activity, have poor luminescent properties. Herein, to overcome this problem by using reactions of nucleophilic aromatic hydrogen substitution (SNH), we have designed a series of novel 4-heteroaryl-substituted 2-aryl-2H-benzo[4,5]imidazo[1,2-a][1,2,3]triazolo[4,5-e]pyrimidine fluorophores possessing a planarized intramolecular charge transfer (PLICT) state. All these fluorophores exhibited high luminescence quantum yields (up to 60%) and large Stokes shift values of up to 7459 cm−1. Among them, the fluorophore 4h was found to exhibit the most pronounced positive solvatochromic effect and the probe 4f exhibited the most pronounced aggregation induced emission characteristics. This AIE behavior was further confirmed by means of time-resolved fluorescence lifetime measurements as well as DFT-assisted geometry optimization studies. In the presence of trifluoroacetic acid (TFA) compound 4h exhibited a well-pronounced acidochromism via visible color change from yellow-green to orange which returned to the original yellow-green solution after the addition of triethylamine (TEA). The Stern-Volmer constant for the probe 4h towards TFA was 38 M−1. Finally, for the compounds 4f, g, h theoretical calculations in the ground and excited states in different solvents were carried out to confirm the PLICT process. Based on all above the herein reported PLICT fluorophores 4a-h can be successfully applied as biological probes and optical switches.

AB - The combination of excellent luminescence with high solvent polarity effect and aggregation induced emission (AIE) is an ideal combination for creating fluorophores/probes with high microenvironmental sensitivity. However, many push-pull chromophores of the D−A type in common intramolecular charge transfer (ICT) state with a significant solvatochromic effect and AIE activity, have poor luminescent properties. Herein, to overcome this problem by using reactions of nucleophilic aromatic hydrogen substitution (SNH), we have designed a series of novel 4-heteroaryl-substituted 2-aryl-2H-benzo[4,5]imidazo[1,2-a][1,2,3]triazolo[4,5-e]pyrimidine fluorophores possessing a planarized intramolecular charge transfer (PLICT) state. All these fluorophores exhibited high luminescence quantum yields (up to 60%) and large Stokes shift values of up to 7459 cm−1. Among them, the fluorophore 4h was found to exhibit the most pronounced positive solvatochromic effect and the probe 4f exhibited the most pronounced aggregation induced emission characteristics. This AIE behavior was further confirmed by means of time-resolved fluorescence lifetime measurements as well as DFT-assisted geometry optimization studies. In the presence of trifluoroacetic acid (TFA) compound 4h exhibited a well-pronounced acidochromism via visible color change from yellow-green to orange which returned to the original yellow-green solution after the addition of triethylamine (TEA). The Stern-Volmer constant for the probe 4h towards TFA was 38 M−1. Finally, for the compounds 4f, g, h theoretical calculations in the ground and excited states in different solvents were carried out to confirm the PLICT process. Based on all above the herein reported PLICT fluorophores 4a-h can be successfully applied as biological probes and optical switches.

KW - Acidochromic effect

KW - Aggregation

KW - Azoloazine

KW - Charge transfer

KW - Push-pull fluorophores

KW - Solvent effect

UR - http://www.scopus.com/inward/record.url?scp=85130231023&partnerID=8YFLogxK

UR - https://www.mendeley.com/catalogue/60629f99-43b4-3cee-90ab-fd9d97ddb183/

U2 - 10.1016/j.dyepig.2022.110405

DO - 10.1016/j.dyepig.2022.110405

M3 - Article

AN - SCOPUS:85130231023

VL - 204

JO - Dyes and Pigments

JF - Dyes and Pigments

SN - 0143-7208

M1 - 110405

ER -