A one-pot protocol has been developed to obtain a series of luminescent heteroleptic diarylborinic complexes bearing the 2-fluoro-3-pyridyl and another aryl group attached to the boron atom chelated with a simple or functionalized 8-oxyquinolinato ligand. The tetrahedral geometry around the boron atom in all compounds has been established by the 11B NMR spectroscopy and/or X-ray diffraction technique. In the solution, the obtained complexes have emission maxima ranging from 502 to 525 nm at room temperature. The quantum yield of emission significantly depends on the type and position of the substituents in the 8-oxyquinolinato ligands and aryl rings. An interpretation of the experimental UV–vis absorption and emission spectral data is supported by theoretical calculations of the frontier molecular orbitals. Marcus theory was used to theoretically evaluate charge-transport properties of the obtained complexes.

A series of diarylborinic complexes with salicydeneaniline ligands bearing various functional groups at the 6-position have been synthesized in high yields by applying a straightforward one-pot multicomponent protocol. UV-Vis measurements revealed the influence of electronic character of substituents on the observed maximum of emission (λem). This has been confirmed by a relatively strong linear correlation (R(2) = 0.92) of λem with Hammett σp(+) constants. Such a correlation was investigated using a QTAIM analysis of the charge density distribution. Absorption and emission bands for the obtained systems span between 390-437 nm and between 506-590 nm, respectively, with quantum yields reaching 17%. Time-dependent UV-Vis absorption measurements revealed that diphenylborinic salicydeneaniline complexes undergo slow degradation in solution under ambient conditions. In contrast, the use of a naphthalene-based chromophore or the introduction of fluorinated phenyl groups at the boron atom resulted in stable systems.

A detailed experimental characterization and theoretical evaluation of optical as well as other relevant physicochemical properties of a series of 9,10-dihydro-9,10-diboraanthracene bis(8-oxyquinolinates) and a few other related systems is reported. The obtained compounds exhibit green luminescence with quantum yields of emission up to 63% in CH 2 Cl 2 . Single crystal X-ray diffraction studies indicate that 9,10-dihydro-9,10-diboraanthracene complexes exist either as bent conformers (stabilized by a weak intramolecular CH…O interaction bringing two 8-oxyquinolinato ligands closer to each other) or symmetrical ones (bearing both ligands related by the centre of symmetry and separated one from the other). Theoretical calculations revealed that the LUMO levels are lower for the bent conformers than for the symmetrical ones. This suggests that the luminescent properties of the studied compounds are affected by their specific structural properties. The obtained compounds were used as emitters for the construction of organic light emitting diodes (OLEDs). The highest luminance of ca. 2,000 cd·m −2 was recorded for the device containing only 2.0 wt% of 1,6-difluoro-9,10-dihydro-9,10-diboraanthracene core in the poly(Nvinylcarbazole/2-t-butylphenyl-5-biphenyl-1,3,4-oxadiazole (PVK:PBD) matrix. The fabricated OLEDs exhibit current efficiency in the range from 0.5 to 1.1 cd·A −1 .

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Single crystal X-ray structures of two polymorphs of (2-fluoro-3-pyridyl)(2,2'-biphenyl)borinic 8-oxyquinolinate: orthorhombic (space group Pca21), and triclinic (space group P1̄) have been established and analysed. A fast rate of crystallization results in the orthorhombic polymorph, whereas slow crystallization gives the triclinic polymorph. Physicochemical and theoretical results prove that both polymorphs form similar crystals with very similar geometry of molecules. The main differences between both forms are intermolecular interactions and their impact on the charge transporting properties of both polymorphs which was evaluated through Marcus theory. The orthorhombic polymorph is a slightly more effective electron and hole transporting material than the other polymorph. In both forms the CH···π interactions contributed the most to the CT properties. Small changes in the molecular geometry of moieties in both polymorphs affect their molecular energies significantly.

The crystal and molecular structure of IJ2-fluoro-3-pyridyl)IJ4-iodophenyl)borinic 8-oxyquinolinate has been determined at room temperature at pressures ranging from ambient to 4.9 GPa in approximately 1 GPa steps. The crystal structure symmetry is conserved during the compression while the a, b and c unit cell dimensions were compressed by 7.5%, 8.0% and 6.9%, respectively. The crystal cell volume decreased by 19.4%. The analysis of the compression of the crystal was supported by computational results obtained with the PASCAL code. They proved that the crystal compression proceeds almost isotropically. A combination of Hirshfeld surface analysis and PIXEL calculations indicated the formation of multiple new contacts involving fluorine⋯fluorine and iodine⋯π-density. Energies of interactions calculated for the observed motifs present in the crystal were rationalized on the basis of contacts observed for these motifs. Further analysis based on the Marcus model was performed to trace the possible changes in the charge transport properties of the crystal. The analysis showed that electron and hole transport properties are not affected in the same way by the compression. However, hydrostatic pressure did not affect which charge transport (electron or hole) is the dominant one for this material.

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