Fluorescence-Enhanced Chemosensor for Metal Cation Detection Based on Pyridine and Carbazole

A series of donor–acceptor systems incorporating a carbazole moiety as the donating unit and pyridine moiety as the accepting unit have been designed and synthesized. The spectroscopic and electrochemical behaviors of the carbazole derivatives demonstrate that the carbazole unit interacts with the electron-accepting group through the π-conjugated spacer, thus leading to the intramolecular charge transfer (ICT). The pyridine-substituted carbazole derivatives show significant sensing and coordinating properties toward a wide range of metal cations. Compound <b>S2</b> exhibits fluorescence enhancement upon association with transition metal cations, and compound <b>V3</b> shows high selectivity for Cu²⁺ among this series of materials. DFT calculations indicate the different association abilities of the dyes and the enhancement of ICT upon addition of the metal cations

AIE-Active Fluorene Derivatives for Solution-Processable Nondoped Blue Organic Light-Emitting Devices (OLEDs)

A series of fluorene derivatives end-capped with diphenylamino and oxadiazolyl were synthesized, and their photophysical and electrochemical properties are reported. Aggregation-induced emission (AIE) effects were observed for the materials, and bipolar characteristics of the molecules are favored with measurement of carrier mobility and calculation of molecular orbitals using density functional theory (DFT). Using the fluorene derivatives as emitting-layer, nondoped organic light-emitting devices (OLEDs) have been fabricated by spin-coating in the configuration ITO/PEDOT:PSS­(35 nm)/PVK­(15 nm)/<b>PhN-OF­(</b><i><b>n</b></i><b>)-Oxa</b>(80 nm)/SPPO13­(30 nm)/Ca­(8 nm)/Al­(100 nm) (<i>n</i> = 2–4). The best device with <b>PhN-OF­(</b><b>2</b><b>)-Oxa</b> exhibits a maximum luminance of 14 747 cd/m², a maximum current efficiency of 4.61 cd/A, and an external quantum efficiency (EQE) of 3.09% in the blue region. Investigation of the correlation between structures and properties indicates that there is no intramolecular charge transfer (ICT) increase in these molecules with the increase of conjugation length. The device using material of the shortest conjugation length as emitting-layer gives the best electroluminescent (EL) performances in this series of oligofluorenes