Adiabatic Deprotonation as an Important Competing Pathway to ESIPT in Photoacidic 2-Phenylphenols.

MENA, LEANDRO; VERA, MARIANO DOMINGO ADOLFO; BAUMGARTNER, MARIA TERESA; JIMENEZ, LILIANA

PHYSICAL CHEMISTRY CHEMICAL PHYSICS

ROYAL SOC CHEMISTRY

Lugar: London; Año: 2019 p. 1 - 10

1463-9076

ESIPT (Excited State Intramolecular Proton Transfer) to C atom in 2-phenylphenol is known to occur as an intrinsicallyinefficient process; however, to the best of our knowledge, a structure-ESIPT efficiency relationship has not beenelucidated yet. Here we show that there exists a competitive interplay between photoacidity and ESIPT efficiency for 2-phenylphenol system. The attachment of electron withdrawing groups to the phenol moiety promotes adiabaticdeprotonation in excited state and diminish the charge transfer character of excitations, both factors contributing todecrease the ESIPT reaction yield. On the other hand, unfavorable conformational distribution in ground state also appearsas another important aspect responsible for the low ESIPT extent of 2-phenylphenol. A new derivative bearing electrondonor, bulky substituents at ortho and para positions of the phenol ring shows an outstanding ESIPT performance, whichdemonstrates that the efficiency of the process can be significatively enhanced by modifying the substitution pattern. Weanticipate our results will help guide molecular design to produce new compounds with high ESIPT efficiency