Krzysztof Durka

Heteroleptic (2-fluoro-3-pyridyl)arylborinic 8-oxyquinolinates for the potential application in organic light-emitting devices.

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 (11)B 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.

Competition between hydrogen and halogen bonding in the structures of 5,10-dihydroxy-5,10-dihydroboranthrenes.

X-ray crystallographic and computational studies are reported for a series of boranthrenes, substituted with halogen atoms. The role of competitive hydrogen (O-H...O, O-H...F, C-H...O) and halogen (Cl...Cl, O...Br, F...F) bonding interactions on the molecular arrangement in the crystal structures is discussed. The structural analysis and calculations reveal that the O-H...O hydrogen bond in the unsubstituted derivative 5,10-dihydroxy-5,10-dihydroboranthrene, C12H10B2O2, is of moderate strength (ca -20 kJ mol(-1)), but weaker than that in the related thiophene derivative 4,8-dihydro-4,8-dihydroxy-p-diborino[2,3-b:5,6-b]dithiophene, C8H6B2O2S2 (ca -40 kJ mol(-1)). This is due to shielding of the OH group by the H atoms in the β-position of the boranthrene unit. Structural diversity derived from the flexibility of the O-H...O hydrogen bond facilitates the occurrence of other competitive interactions. For instance, in the 1,6-difluoro derivative, C12H8B2F2O2, the crystal packing results from O-H...F and F...F interactions. In turn, the 1,6-dibromo derivative, C12H8B2Br2O2, is dominated by Br...O halogen-bond interactions. In the most interesting case, the 1,6-dichloro derivative, C12H8B2Cl2O2, molecular disorder leads to the formation of two different supramolecular arrangements co-existing in the crystal lattice, one based on the Cl...Cl and C-H...O bonds, and the other stabilized by O-H...O hydrogen bonds. Calculations performed with density-functional theory (DFT; CRYSTAL09) and PIXEL methodologies show that both lattices are characterized by similar energy values (ca -100 kJ mol(-1)). A mixed arrangement with random or short-range-ordered molecular orientations can also be expected.

Efficient 8-oxyquinolinato emitters based on a 9,10-dihydro-9,10-diboraanthracene scaffold for applications in optoelectronic devices

A detailed experimental characterization and theoretical evaluation of the 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 of up to 63% in CH2Cl2. 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 two ligands related by a centre of symmetry and separated from each 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. 2000 cd m−2 was recorded for the device containing only 2.0 wt% of the 1,6-difluoro-9,10-dihydro-9,10-diboraanthracene core in the poly(N-vinylcarbazole/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.

Highly Fluorescent Red-Light Emitting Bis(boranils) Based on Naphthalene Backbone

Ten bis(boranils) differently substituted at the boron atom and iminophenyl groups were synthesized from 1,5-dihydroxynaphthalene-2,6-dicarboxaldehyde using a simple one-pot protocol. Their photophysical properties can be easily tuned in a wide range by the variation of substituents. Their absorption and emission spectral bands are significantly red-shifted (λmax = 495-590 nm, λem = 533-683 nm) when compared with simple boranils, whereas fluorescence quantum yields are strongly improved to reach 83%. The attachment of pendant NO2 and NEt2 groups at the opposite positions of the π-conjugated bis(boranil) scaffold resulted in the formation of an unprecedented system featuring push-pull architecture.

Crystal structure of (2′,3,6′-tri­chloro­biphenyl-2-yl)boronic acid tetra­hydro­furan monosolvate

In this manuscript the molecular and supramolecular structure of 2′,3,6′-trichlorobiphenyl-2-ylboronic acid tetrahydrofuran monosolvate is presented

Impact of High Pressure on Metallophilic Interactions and Its Consequences for Spectroscopic Properties of a Model Tetranuclear Silver(I)-Copper(I) Complex in the Solid State

Structure-property relationships were investigated via combined high-pressure spectroscopic and X-ray diffraction techniques for a model luminescent Ag2Cu2L4 (L = 2-diphenylphosphino-3-methylindole) complex in the crystalline state. The experimental results were contributed by theoretical calculations, compared with the previously evaluated light-induced geometrical changes, and discussed in the context of available literature to date. To the best of our knowledge, this is the first study of this kind devoted to a coinage-metal complex for which the argentophilic interactions are crucial. High-pressure X-ray diffraction and optical spectroscopy experiments showed close correspondence between structural changes and optical properties. The unit-cell angles, absorption edges, emission maxima, decay lifetimes and silver-copper bond trends, all change around 2-3 GPa. A blue-shift to red-shift switch when increasing the pressure was observed for both absorption and emission spectra. This is unique behavior when compared to the literature-reported coinage metal systems. It also occurred that the pressure-induced structural changes differ notably from the geometrical distortions observed for the excited state. Interestingly, shortening of the Ag-Ag bond itself does not ensure the red shift of the absorption and emission spectra. All the optical spectroscopy data are suggestive of an important role of defects, likely related to the lack of a hydrostatic pressure transmitting medium, for pressures higher than 3 GPa.

CCDC 1449071: Experimental Crystal Structure Determination

Related Article: Katarzyna Jarzembska, Radoslaw Kaminski, Krzysztof Durka, Marcin Kubsik, Krzysztof Nawara, Ewelina Witkowska, Sergiusz Lulinski, Jacek Waluk, Ireneusz Glowacki, Krzysztof Wozniak|2017|Dyes Pigm.|138|267|doi:10.1016/j.dyepig.2016.11.039

Crystal structure of (2-benzyl­oxy­pyrimidin-5-yl)boronic acid

The boronic acid group in the title compound, C11H11BN2O3, adopts a syn–anti conformation and is almost coplanar with the aromatic rings , making a dihedralangle of 3.8 (2)°. In the crystal, adjacent molecules are linked via pairs of O—H⋯O interactions, forming centrosymmetric dimers with an R 2 2(8) motif, which have recently been shown to be energetically very favorable (Durka et al., 2012 ▶, 2014 ▶). The hydroxy groups in an anti conformation are engaged in lateral hydrogen-bonding interactions with N atoms from neighbouring molecules, leading to the formation of chains along [001]. O⋯B [3.136 (2) Å] and C(π)⋯B [3.393 (2) Å] stacking interactions in turn link parallel chains of centrosymmetric dimers into layers parallel to (010).

2-Meth­oxy-3-(tri­methyl­sil­yl)phenyl­boronic acid

The molecular structure of the title compound, C10H17BO3Si, features an intramolecular O—H⋯O hydrogen bond; the boronic group group has an exo–endo conformation. In the crystal, the molecules interact with each other by O—H⋯O hydrogen bonds, producing centrosymmetric dimers that are linked by weak π–π stacking interactions featuring specific short B⋯C contacts [e.g. 3.372 (2) Å], forming an infinite columnar structure aligned along the a-axis direction.

Structural, energetic and charge-density investigations of triptycene and its selected derivatives

Triptycene and its derivatives, due to their characteristic rigid framework with the point symmetry, play an important role in crystal engineering, and are often employed as molecular machine building blocks. New structures of chloro-, methyloderivatives of tripytcenes are presented in details and compared to the related structures deposited in CSD. It occurred that the studied triptycene derivatives create two distinguishable network types, one of which constitutes a layered architecture. Interestingly, the 1,4,-dichloro-9,10-dimethylotrip tycene (DCDMT) appears in two polymorphic forms. It crystallizes in the P21/c space group at room temperature with one molecule in the asymmetric part of the unit cell. However, when the temperature is decreased to 100 K, its symmetry is partially broken (the inversion centre vanishes). For all the measured and related CSD structures periodic ab-initio calculations in the CRYSTAL09[1] and PIXEL[2] packages were conducted and careful analyses of lattice and dimer interaction energies were performed. The influence of substituent on crystal packing and lattice energy stability was investigated. In the case of triptycene and 9,10-dimethylotriptycene (DMT), X-ray high resolution measurements and multipolar refinements were performed, and thus experimental charge density distributions were obtained and analysed by means of the AIM theory. During the refinement of DMT, it was necessary to include the anharmonic thermal motion effect for carbon atom from the methyl group. Additionally, different approaches to hydrogen atom treatment were tested.