title: Fine tuning the energetics of excited-state intramolecular proton transfer (ESIPT): white light generation in a single ESIPT system.
abstract: Using 7-hydroxy-1-indanone as a prototype (I), which exhibits excited-state intramolecular proton transfer (ESIPT), chemical modification has been performed at C(2)-C(3) positions by fusing benzene (molecule II) and naphthalene rings, (molecule III). I undergoes an ultrafast rate of ESIPT, resulting in a unique tautomer emission (λ(max) ∼530 nm), whereas excited-state equilibrium is established for both II and III, as supported by the dual emission and the associated relaxation dynamics. The forward ESIPT (normal to proton-transfer tautomer species) rates for II and III are deduced to be (30 ps)(-1) and (22 ps)(-1), respectively, while the backward ESIPT rates are (11 ps)(-1) and (48 ps)(-1). The ESIPT equilibrium constants are thus calculated to be 0.37 and 2.2 for II and III, respectively, giving a corresponding free energy change of 0.59 and -0.47 kcal/mol between normal and tautomer species. For III, normal and tautomer emissions in solid are maximized at 435 and 580 nm, respectively, achieving a white light generation with Commission Internationale de l'Eclairage (CIE) (0.30, 0.27). An organic light-emitting diode based on III is also successfully fabricated with maximum brightness of 665 cd m(-2) at 20 V (885 mA cm(-2)) and the CIE coordinates of (0.26, 0.35). The results provide the proof of concept that the white light generation can be achieved in a single ESIPT system.
authors.affiliation: Department of Chemistry, National Taiwan University, Taipei, 10617 Taiwan, ROC.
authors.forename: Kuo-Chun
authors.initials: KC
authors.lastname: Tang
authors.forename: Ming-Jen
authors.initials: MJ
authors.lastname: Chang
authors.forename: Tsung-Yi
authors.initials: TY
authors.lastname: Lin
authors.forename: Hsiao-An
authors.initials: HA
authors.lastname: Pan
authors.forename: Tzu-Chien
authors.initials: TC
authors.lastname: Fang
authors.forename: Kew-Yu
authors.initials: KY
authors.lastname: Chen
authors.forename: Wen-Yi
authors.initials: WY
authors.lastname: Hung
authors.forename: Yu-Hsiang
authors.initials: YH
authors.lastname: Hsu
authors.forename: Pi-Tai
authors.initials: PT
authors.lastname: Chou
mesh_terms: D007189:Indans / Q000138:chemical synthesis / Q000737:chemistry*; D008027:Light; D008958:Models, Molecular; D015394:Molecular Structure; D011789:Quantum Theory; D013816:Thermodynamics
chemical_list: D007189:Indans