A series of new luminescent non-planar 1,8-naphthyridine derivatives giving coloured and close-to-white electroluminescence spectra

Abstract

We report a synthesis of 37 new 1,8-naphthyridine based compounds having a non-planar bicyclic moiety (bicyclo[3.3.1]nonane, bicyclo[3.3.0]octane and camphor). We measured energetic characteristics (EHOMO=[−5.9; −5.4] eV, ELUMO=[−3.4; −2.4] eV and Eg_opt=[2.3; 3] eV), tested photoluminescence (PL) properties in chloroform solution (PL peaks at 390–490 nm range; QY reaching 53%) and produced multilayer OLED structures with our new materials as an emissive layer (EML). With changing the EML material, we observed electroluminescence (EL) covering a wide colour spectrum: red-orange, yellow, lettuce-green, green, blue-green (compared to violet from a control device). A broad white EL spectrum was registered for OLEDs with duplex non-planar “V” conformation molecules as an EML. The analysis of the results let us obtain precious information about the influence of molecular structure peculiarities on PL and EL spectra, as well as on values of the HOMO, the LUMO and Eg_opt, that are universal for all molecular systems.