The synthesis of new chiral copper(ii) complexes with terpene derivatives of ethylenediamine and the results of studying their antibacterial, antifungal and antioxidant activity in vitro are discussed.

High temperature coupling of 6-aryl-5-cyano-3-(pyridin-2-yl)-1,2,4-triazines with 2-amino-4-aryloxazoles proceeds as the inverse demand Diels–Alder reaction between the oxazole moiety as dienophile and the 1,2,4-triazine moiety as diene to construct new 4,5-diaryl-6-cyano-3-hydroxypyridin-2-yl fragment. A reaction mechanism is proposed, and the structure of the key-product is proved by the X-ray diffraction analysis.

This study presents the synthesis and optical properties of a new class of bright green–yellow fluorescent dyes with potential applications in bioimaging. A facile synthetic route via the chelation of aryl(hetaryl)aminoacryloylthiophene scaffolds with a BF₂ fragment is presented. The photophysical properties of the dyes are attributed to the nature and position of electron-donating and electron-withdrawing substituents. Upon coordination to a BF₂ fragment, characteristic emission was observed, with λ_em ranging from 503 to 543 nm and quantum yields of 0.14–0.42. Compared with parent aryl(hetaryl)aminoacryloylthiophenes, a significant red shift in absorption (up to 480 nm in solution) and emission (up to 543 nm in solution and 610 nm in the solid state) and high chemical stability and photostability were observed. The electron-accepting character of the substituents on the terminal aromatic ring or replacing this fragment with pyridine or pyrazine moieties resulted in increased quantum yields. To gain insight into the electronic structures and optical properties, quantum mechanical calculations were performed. The results of (TD-)DFT calculations supported the structural and spectroscopic data and showed the features of electronic distribution in the frontier molecular orbitals and active electrophilic and nucleophilic sites in the compounds investigated. Synthesized BF₂ complexes are promising dyes for cell imaging and flow cytometry owing to their ready penetration and accumulation in cells.