Tuning the dual emission of keto/enol forms of excited-state intramolecular proton transfer (ESIPT) emitters via intramolecular charge transfer (ICT)

Correlation between Excited-State Intramolecular Proton Transfer and Electron Population on Proton Donor/Acceptor in 2-(2′-Hydroxyphenyl)oxazole Derivatives

“…The solvent-polarity-sensitive N* fluorescence (Figure S4) also indicates that the ESICT occurs before proton transfer, and the following ESIPT dynamics are strongly influenced by the ESICT. ,,, The coupling between ESICT and ESIPT can be effectively modulated by different substituents on the parent HPO. Such a viewpoint could be verified by two recently reported HPO derivatives as well, in which exchanging the position of electron-donating TPA and electron-withdrawing triphenylboron (TPB) directly changes the direction of the ESIPT reaction . Herein, we consider ICT as the main influencing factor of the ESIPT tendency and attempt to establish a correlation between them.…”

“…Such a viewpoint could be verified by two recently reported HPO derivatives as well, in which exchanging the position of electron-donating TPA and electron-withdrawing triphenylboron (TPB) directly changes the direction of the ESIPT reaction. 46 Herein, we consider ICT as the main influencing factor of the ESIPT tendency and attempt to establish a correlation between them. Other factors that may affect the ESIPT reaction, such as the electronic coupling between N* and T*, vibration-driven effect, etc., are not considered in this work.…”

Tuning ESIPT-coupled luminescence by expanding π-conjugation of a proton acceptor moiety in ESIPT-capable zinc(ii) complexes with 1-hydroxy-1H-imidazole-based ligands

“…105,106,119 It is well known that the proton transfer abilities and emission properties of ESIPT-capable molecules can be tuned by substitution on the proton-donating and protonaccepting cores, as well as by the degree of π-conjugation. [120][121][122][123][124][125][126][127][128][129][130][131][132][133][134][135][136] As far as the degree of π-conjugation is concerned, extending the π-conjugated system on the protondonating part of the molecule can frustrate the ESIPT process, since the excited state is located predominantly on the ESIPT-incapable part of the molecule and involves the ESIPT site only to a small extent. 135,136 Instead, the extension of the π-conjugated system on the proton-accepting moiety could facilitate the ESIPT process due to better delocalization of a positive charge.…”

Modulating the spectroscopy and dynamics of a proton-transfer dye by functionalizing with phenyl groups

“…[23][24][25] Indeed, over the last four decades, research studies have dedicated great efforts to design, develop, and multidisciplinary explore (theoretically, experimentally and their practical real-world applicability) a vast number of molecules and systems undergoing ICT and ESIPT reactions. [26][27][28][29][30][31] Three molecules stand out among all of them, 2-(2-hydroxyphenyl)benzoxazole (HBO), 2-(2-hydroxyphenyl)benzimidazole (HBI) and 2-(2-hydroxyphenyl)benzothiazole (HBT), as they are the starting point for the generation of many derivatives, showing outstanding optical and photodynamical properties. [32][33][34][35][36][37][38][39][40][41][42] Interestingly, some of these systems can undergo either ESIPT or ICT, but there exist others where both reactions can be coupled.…”