Synthesis, spectral and electrochemical properties of selected boron ketiminates with aminocoumarin fragment

• Published in: Monatshefte für Chemie Vol. 149; no. 10; pp. 1795 - 1811
• Main Authors: Doušová, Hana, Almonasy, Numan, Mikysek, Tomáš, Váňa, Jiří, Nepraš, Miloš, Frumarová, Božena, Dvořák, Miroslav, Růžičková, Zdeňka, Šimůnek, Petr
• Format: Journal Article
• Language: English
• Published: Vienna Springer Vienna 01.10.2018; Springer Nature; Springer Nature B.V
• Subjects: Agglomeration; Analytical Chemistry; Boron compounds; Chemistry; Chemistry and Materials Science; Chemistry, Multidisciplinary; Chemistry/Food Science; Electrochemical analysis; Electrochemistry; Emission analysis; Energy gap; Fluorescence; Inorganic Chemistry; NMR; Nuclear magnetic resonance; Optical properties; Organic Chemistry; Original Paper; Oxidation; Phosphorescence; Physical Chemistry; Physical Sciences; Science & Technology; Theoretical and Computational Chemistry; X-ray diffraction; X-ray structure determination; Fluorescence; Electrochemistry; Enaminones; NMR spectroscopy; UV/Vis spectroscopy; AIE; ORGANOBORON COMPOUNDS; FLUORESCENT BF2 COMPLEXES; MOLECULAR-ORIGINS; X-RAY-DIFFRACTION; CRYSTAL-STRUCTURES; SUBSTITUTED COUMARINS; PHOTOPHYSICAL PROPERTIES; OPTOELECTRONIC PROPERTIES; CONJUGATED POLYMERS; AGGREGATION-INDUCED EMISSION
• ISSN: 0026-9247; 1434-4475
• DOI: 10.1007/s00706-018-2262-3

Six novel oxazaborines based on 7-aminocoumarin substituted by either fluoride or phenyl group on the boron atom were prepared from the corresponding enaminones. The compounds were characterized by means of 1 H, 13 C, 19 F, and 11 B NMR in solution, X-ray diffraction in crystal, UV–Vis spectroscopy, and electrochemistry. The observed optical properties were compared to the DFT calculations. Dynamic behaviour of selected oxazaborines was studied by means of 19 F and 1 H VT NMR and 2D EXSY. Both the enaminones and oxazaborines exhibit relatively strong fluorescence both in solid state and in frozen 2-methyltetrahydrofuran at 77 K, but none in solution. In some cases, phosphorescence was observed as well. Preliminary aggregation tests revealed aggregation induced emission (AIE) properties of the studied molecules. Concerning the electrochemical properties, the first reduction of all the oxazaborines studied proceeds as transport controlled one-electron (quasi)reversible process whereas the first oxidation of BPh 2 oxazaborines proceeds as a two-electron irreversible process most probably of the ECE type. The oxidation of BF 2 compounds was not possible to obtain within the given potential window. Analysis of frontier orbitals showed that change from BF 2 to BPh 2 leads to decrease of energy gap. Graphical abstract .