ESIPT OR ICT? HOW THE MODULATION OF EXCITED-STATE DETERMINES THE APPLICATIONS OF HYDROXYPHENYLBENZOTHIAZOLE DYES

Franciela Arenhart Soares; Eduard Westphal; Ivan H Bechtold

Todos os Trabalhos

Trabalho

Título do Trabalho

ESIPT OR ICT? HOW THE MODULATION OF EXCITED-STATE DETERMINES THE APPLICATIONS OF HYDROXYPHENYLBENZOTHIAZOLE DYES

Autores

Franciela Arenhart Soares
Eduard Westphal
Ivan H Bechtold

Modalidade

Pôster - resumo

Área temática

Materiais e biomateriais

Data de Publicação

27/05/2026

País da Publicação

Brasil

Idioma da Publicação

pt-BR

Página do Trabalho

https://www.even3.com.br/anais/workshop-do-ineo-2026/1458197-esipt-or-ict-how-the-modulation-of-excited-state-determines-the-applications-of-hydroxyphenylbenzothiazole-dyes

ISBN

978-65-272-2467-9

Palavras-Chave

Excited-state intramolecular proton transfer, intramolecular charge transfer, solvatochromism, excited-state dynamics

Resumo

Excited-State Intramolecular Proton Transfer (ESIPT) dyes have attracted considerable attention owing to their unique four-level fluorescence cycle, which arises from tautomerization in the excited state(1,2). This process imparts distinctive photophysical features, including large Stokes shifts, high photostability, and pronounced sensitivity to the surrounding environment(3). In particular, the balance between the enol (E*) and keto (K*) excited-state tautomers is strongly influenced by solvation, enabling dual fluorescence emission that can be tuned by changes in the microenvironment(4,5). These properties make ESIPT dyes highly versatile for applications ranging from bioimaging to optoelectronics(4,6,7). However, in polar environments or under specific substitution patterns, ESIPT efficiency can be undermined by competing excited-state processes, namely intramolecular charge transfer (ICT)(8–10). In this work, we aim to contribute to the understanding of this complex relationship through the design and synthesis of a library of 2-(2-hydroxyphenyl)benzothiazole (HBT) derivatives, where ESIPT and ICT contributions are intentionally modulated. This way, derivatives of HBT containing either a carbamate or a carbonate substituent were prepared through a one-pot, base-selective acylation strategy. The optical behavior of these compounds was systematically studied using UV-vis and fluorescence spectroscopy in solvents of varying polarity and viscosity. Quantum yield and time-resolved fluorescence data were collected to analyze the excited-state dynamics. Our findings reveal that carbonate-substituted 5-HBTE compounds exhibit a classical ICT character with Stokes shifts in the range of ~ 4000 cm-1 ( ~ 55 nm) while the positional isomer 4-HBTE showed progressive Stokes shifts with increasing polarity. Moreover, for 4-HBTE surprisingly large Stokes shifts (> 12000 cm-1 or 180 nm) and solvent-sensitive fluorescence were observed. While the ESIPT active analogs 4- and 5-HBTA showed negative solvatochromism and high quantum yield in the solid state, 4- and 5-HBTE derivatives showed positive solvatochromism and elevated quantum yields in solution. Understanding the balance between ESIPT and ICT in dyes provides a promising pathway for extending their applicability to highly polar environments, thereby advancing their potential in polarity probes and material design. References: 1 F. A. Soares, G. Martinez-Denegri, L. A. Baptista, P. Sleczkowski and A. Steinbüchel, J. Phys. Chem. C, 2023, 127, 17624–17636. 2 G. Martínez-Denegri, F. A. Soares and P. Sleczkowski, Adv. Opt. Mater., 2025, 13, 2403073. 3 Y. Wang, M. Hu, Q. Yue, F. Xiaoqing and Y. Zhao, RSC Adv., 2024, 14, 39759–39768. 4 T. Pariat, M. Munch, M. Durko-Maciag, J. Mysliwiec, P. Retailleau, P. M. Vérité, D. Jacquemin, J. Massue and G. Ulrich, Chem. Eur. J., 2021, 27, 3483–3495. 5 T. Pariat, T. Stoerkler, C. Diguet, A. D. Laurent, D. Jacquemin, G. Ulrich and J. Massue, J. Org. Chem., 2021, 86, 17606–17619. 6 V. Trannoy, A. Léaustic, S. Gadan, R. Guillot, C. Allain, G. Clavier, S. Mazerat, B. Geffroy and P. Yu, New J. Chem., 2021, 45, 3014–3021. 7 V. R. Mishra, C. W. Ghanavatkar and N. Sekar, ChemistrySelect, 2020, 5, 2103–2113. 8 N. A. Shekhovtsov and M. B. Bushuev, J. Mol. Liq., 2022, 361, 119611. 9 G. Wiethaus, J. M. Toldo, F. da Silveira Santos, R. da Costa Duarte, P. F. B. Gonçalves and F. S. Rodembusch, Phys. Chem. Chem. Phys., 2019, 21, 4408–4420. 10 S. K. Behera, A. Karak and G. Krishnamoorthy, J. Phys. Chem. B, 2015, 119, 2330–2344. Acknowledgments: FAPESP - 2025/27044-5, CNPq - 408449/2024-1 and CNPq 446343/2024-2

Título do Evento: Workshop do INEO 2026
Cidade do Evento: Nazaré Paulista
Título dos Anais do Evento: Anais do Workshop do INEO 2026
Nome da Editora: Even3
Meio de Divulgação: Meio Digital

Como citar

SOARES, Franciela Arenhart; WESTPHAL, Eduard; BECHTOLD, Ivan H. ESIPT OR ICT? HOW THE MODULATION OF EXCITED-STATE DETERMINES THE APPLICATIONS OF HYDROXYPHENYLBENZOTHIAZOLE DYES.. In: Anais do Workshop do INEO 2026. Anais...Nazaré Paulista(SP) Hotel Estância Atibainha, 2026. Disponível em: https//www.even3.com.br/anais/workshop-do-ineo-2026/1458197-ESIPT-OR-ICT-HOW-THE-MODULATION-OF-EXCITED-STATE-DETERMINES-THE-APPLICATIONS-OF-HYDROXYPHENYLBENZOTHIAZOLE-DYES. Acesso em: 10/08/2026