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A new pH-responsive fluorescence chromophore with white light emission at pH = 3 was synthesized which has high potential application in the preparation of high-performance lighting devices.

ABSTRACT:The H-bonded complexes formed from interaction between NH 2 NO (NA) and H 2 O 2 (HP) have been investigated by using B3LYP and MP2 methods with a wide range of basis sets. We found six H-bonded complexes in which three of them have cyclic structure. Calculations carried out at various levels show that the sevenmembered cyclic structure with O⅐⅐⅐HO and O⅐⅐⅐HN hydrogen bonding interactions is the most stable complex. The large binding energy obtained for A1 complex probably results from a more linear arrangement of the O⅐⅐⅐HON and OOH⅐⅐⅐OH-bonds in the seven-membered structure A1. The natural bond orbital (NBO) analysis and the Bader's quantum theory of atoms in molecules have been used to elucidate the interaction characteristics of the NA-HP complexes. The NBO results reveal that the charge transfer energy corresponds to the H-bond interactions for A1 complex is grater than other complexes. The electrostatic nature of H-bond interactions is predicted from QTAIM analysis.

Highly efficient single-component white light emitters (SWLEs), are attractive candidates for the simple and cost-effective fabrication of high-performance lighting devices. This study introduced a donor–π–acceptor and a donor–π–donor stilbene-based chromophores, representing pH-responsive fluorescence. The emitters showed yellow and green fluorescence in their neutral form. At the same time, protonation of the chromophores caused blue fluorescence color with a strong hypsochromic shift. The white light emission (WLE) for these chromophores was observed at approximately pH  3 due to the simultaneous presence of the neutral and protonated forms of the chromophores, covering almost all the emission spectra in the visible region (400–700 nm). These chromophores presented exceptional white light quantum yields (Φ) between 31 and 54%, which was desirable for producing white light-emitting devices. Density functional theory (DFT) and time-dependent (TD)-DFT were applied to study the structural and electronic properties of the chromophores.