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.

ESIPT reaction of potential bioactive heterocyclic Schiff base: Atomic visualization coupled with in vitro spectroscopy

“…Photoinduced electron transfer and proton transfer are important fundamental processes for many biochemical reactions and find numerous applications in scientific field [1][2][3][4][5][6][7][8][9][10][11][12][13]. Amongst all the photoinduced processes, excited state proton transfer are of special interest.…”

Synthesis, Crystal Structure, Spectroscopic Properties, and DFT Studies of 7,9-Dibromobenzo[h]quinolin-10-ol

“…The resulting proton-transfer tautomer (keto-form) exhibits considerable differences in molecular structure and electronic configuration from its corresponding ground state, i.e., a large Stokes shifted tautomer fluorescence. This unique optical property has found many diverse applications such as probes for solvation dynamics [7][8][9] and biological environments [10,11], fluorescence microscopy imaging [12], near-infrared fluorescent dyes [13], nonlinear optical materials [14], photochromic materials [15], chemosensors [16][17][18][19][20], and organic light-emitting diodes [21][22][23][24][25][26]. To expand the scope of 2-based chromophores available for designing systems for laser dyes and fluorescent materials, the present research reports the synthesis of a benzo[h]quinolin-10-ol derivative 7,9-dibromobenzo[h]quinolin-10-ol (1) as well as its X-ray structure, spectroscopic properties, and complementary time-dependent density functional theory (TD-DFT) calculations.…”

TDDFT assessment of excited state intramolecular proton transfer in a panel of chromophore 2-hydroxypyrene-1-carbaldehyde

“…It is worth mentioning that the ESIPT process was found to proceed exceptionally fast at a subpicosecond time scale because it involves a negligible activation barrier [16][17][18][19][20][21][22]. This ultrafast nature of ESIPT molecules attracts highest scientific interest whereby paving potential avenues for prospective applications, such as luminescent materials [23,24], fluorescent chemosensors [25], photostabilizers [26,27], molecular probes [28], metal ion sensors [29][30][31], and organic light emitting devices (OLEDs) [32,33].…”