Near Attack Conformation as Strategy for ESIPT Modulation for White-Light Generation

Two
derivatives salicylidene-4,6-(dimethylamino)­pyridine (KM1)
and salicylidene-5-bromo-4,6-(dimethylamino)­pyridine (KM2) reactive
to excited-state intramolecular proton transfer (ESIPT) were synthesized
as a strategy to produce white light diodes with small organic molecules.
White color resulted from the presence of both normal (420 nm) and
tautomeric (550–580 nm) species emission. The photophysical
features of N* and T* were unveiled in solution and the solid state.
The ESIPT mechanism revealed the influence of near attack conformation
(NAC), and the relevance intramolecular hydrogen bonding (IMHB) further
evaluated by 1H NMR. Organic Light-emitting Diodes (OLEDs)
were ensembled as Al/Ca/PVK:X/PEDOT:PSS/ITO/glass where X = KM1 or KM2 (0.3% mol mol–1) using solution-processed
protocols. KM1 or KM2 was solubilized in poly­(9-vinylcarbazole), PVK,
and the device of KM2 produced a chromaticity of (0.32, 0.27) according
to the Commission Internationale de L’Eclairage (CIE) 1931 scale, which is slightly violet. The same device using
KM1 reached CIE (0.33, 0.34), which is considered extremely close
to pure white.