Effects of Electron-Withdrawing Strengths of the Substituents on the Properties of 4-(Carbazolyl-R-benzoyl)-5-CF3-1H-1,2,3-triazole Derivatives as Blue Emitters for Doping-Free Electroluminescence Devices

The synthesis of four 4-(carbazolyl-R-benzoyl)-5-CF3-1H-1,2,3-triazoles with extra groups ((3-methyl)-phenyl-, 4-fluorophenyl-, quinolinyl-, or (3-trifluoromethyl)-phenyl-) in the acceptor fragment has been reported. The effects of substituents with different electron-withdrawing strengths on the thermal, electrochemical, photophysical, and electroluminescence properties of the synthesized compounds are discussed. The results of X-ray analyses and density functional theory (DFT) calculations support unusual molecular packing and electronic properties. The compounds are capable of glass formation with glass transition temperatures ranging from 54-84 °C. Ionization potentials of the compounds are in the range of 5.98-6.22 eV and electron affinities range from 3.09 to 3.35 eV. Under ultraviolet excitation, the neat films of the compounds exhibit blue emission with photoluminescence quantum yields ranging from 18 to 27%. The films of selected compounds are used for the preparation of host-free light-emitting layers of organic light-emitting diodes with very simple device structures and an external quantum efficiency of 4.6%.

Bioisosteric replacement of 1H-1,2,3-triazole with 1H-tetrazole ring enhances anti-leukemic activity of (5-benzylthiazol-2-yl)benzamides

Previously, we discovered that N-(5-benzyl-1,3-thiazol-2-yl)-4-(5-methyl-1H-1,2,3-triazol-1-yl)benzamide possessed a remarkable cytotoxic effect on 28 cancer cell lines with IC₅₀ < 50 μM, including 9 cancer cell lines, where IC₅₀ was in the range of 2.02-4.70 μM. In the present study, we designed a novel N-(5-benzylthiazol-2-yl)amide compound 3d that was synthesized using the original bioisosteric replacement of 1H-1,2,3-triazole ring by the 1H-tetrazole ring. A significantly enhanced anticancer activity in vitro with an excellent anti-leukemic potency towards chronic myeloid leukemia cells of the K-562 line was demonstrated. Two compounds - 3d and 3l - were highly cytotoxic at nanomolar concentrations towards various tumor cells of the following lines: K-562, NCI-H460, HCT-15, KM12, SW-620, LOX IMVI, M14, UACC-62, CAKI-1, and T47D. As a highlight, the compound N-(5-(4-fluorobenzyl)thiazol-2-yl)-4-(1H-tetrazol-1-yl)benzamide 3d inhibited the growth of leukemia K-562 cells and melanoma UACC-62 cells with IС₅₀ of 56.4 and 56.9 nM (SRB test), respectively. The viability of leukemia K-562 and pseudo-normal HaCaT, NIH-3T3, and J774.2 cells was measured by the MTT assay. Together with SAR analysis, it allowed the selection of a lead compound 3d, which demonstrated the highest selectivity (SI = 101.0) towards treated leukemic cells. The compound 3d caused DNA damage (single-strand breaks detected by the alkaline comet assay) in the leukemic K-562 cells. The morphological study of the K-562 cells treated with compound 3d revealed changes consistent with apoptosis. Thus, the bioisosteric replacement in (5-benzylthiazol-2-yl)amide scaffold proved to be a perspective approach in the design of novel heterocyclic compounds with enhanced anticancer potential.

Exciplex-Forming Systems of Physically Mixed and Covalently Bonded Benzoyl-1H-1,2,3-Triazole and Carbazole Moieties for Solution-Processed White OLEDs

Using the newly designed exciplex-forming 1,2,3-triazole-based acceptors with fast and efficient singlet → triplet intersystem crossing (ISC) processes, carbazole and benzoyl-1H-1,2,3-triazole derivatives were synthesized by Dimroth-type 1,2,3-triazole ring formation and Ullmann-Goldberg C-N coupling reactions. Due to the exciplex formation between covalently bonded electron-donating (carbazole) and 1,2,3-triazole-based electron-accepting moieties with small singlet-triplet splitting (0.07-0.13 eV), the compounds exhibited ISC-assisted bluish-green thermally activated delayed fluorescence. The compounds were characterized by high triplet energy levels ranging from 2.93 to 2.98 eV. The most efficient exciplex-type thermally activated delayed fluorescence was observed for ortho-substituted carbazole-benzoyl-1H-1,2,3-triazole which was selected as a host in the structure of efficient solution-processed white light-emitting diodes. The best device exhibited a maximum power efficiency of 10.7 lm/W, current efficiency of 18.4 cd/A, and quantum efficiency of 7.1%. This device also showed the highest brightness exceeding 10 thousand cd/m². Usage of the exciplex-forming host allowed us to achieve a low turn-on voltage of 3.6 V. High-quality white electroluminescence was obtained with the close to nature white color coordinates (0.31, 0.34) and a color rendering index of 92.

Comparison of synthetic routes for fully substituted (1H-1,2,3-triazol-4-yl)acetic acids

The new fully substituted (1H-1,2,3-triazol-4-yl)acetic acids were synthesized from available precursors (1H-1,2,3-triazol-4-yl)ethanones and 1Н-1,2,3-triazole-4-carboxylic acids, which are easily prepared by the Dimroth reaction from azides and 1,3-dicarbonyl compounds. The practical methods of homologization (the Arndt–Eistert reaction and homologization as a result of nucleophilic substitution by cyanide anion) and the Willgerodt-Kindler reaction were compared. The Willgerodt-Kindler method starting from (5-methyl-1H-1,2,3-triazol-4-yl)ethanones was selected as the most convenient method for the synthesis of 2-(1-aryl-5-methyl-1H-1,2,3-triazol-4-yl)acetic acids, which are promising building blocks for drug discovery. Additionally, (1H-1,2,3-triazol-4-yl)ethanones were studied for the synthesis of alcohols, amines and in the Johnson–Corey–Chaykovsky reaction.

Thermodynamic properties of some isomeric 5-(nitrophenyl)-furyl-2 derivatives

BACKGROUND

The aim of the current work was to determine thermodynamical properties of 5-(nitrophenyl)-2-furaldehyde oximes and 3-[5-(nitrolphenyl)-2-furyl]acrylic acids.

RESULTS

The temperature dependences of saturated vapor pressures of 5-(nitrophenyl)-2-furaldehyde oximes and 3-[5-(nitrolphenyl)-2-furyl]acrylic acids were determined by the Knudsen effusion method. The results are presented by the Clapeyron-Clausius equation in linear form, and via this form, the standard enthalpies of sublimation of compounds were calculated at 298.15 K. The standard molar formation enthalpies of compounds in crystalline state at 298.15 K were determined indirectly from the corresponding standard molar combustion enthalpy, obtained using combustion bomb calorimetry. The non-nearest neighbour interactions (strain) in molecule were defined. The ideal-gas enthalpies of investigated compounds formation and the data available from the literature were used for calculation of group-additivity parameters and the correction terms useful in the application of the Benson correlation.

CONCLUSION

Determining the thermodynamic properties for these compounds will contribute to solving practical problems pertaining to optimization processes of their synthesis, purification and application. It will also provide a more thorough insight regarding the theoretical knowledge of their nature and are necessary for the application of the Benson group-contribution correlation for calculation of Δ f H m ( 298.15 K ) o (g)calc.

Thermodynamic properties of 5(nitrophenyl) furan-2-carbaldehyde isomers

Background

The aim of the current work was to determine thermo dynamical properties of 5(2-nitro phenyl)-furan-2-carbaldehyde, 5(3-nitro phenyl)-furan-2-carbaldehyde and 5(4-nitro phenyl)-furan-2-carbaldehyde.

Results

The temperature dependence of saturated vapor pressure of 5(2-nitro phenyl)-furan-2-carbaldehyde, 5(3-nitro phenyl)-furan-2-carbaldehyde and 5(4-nitro phenyl)-furan-2-carbaldehyde was determined by Knudsen’s effusion method. The results are presented by the Clapeyron–Clausius equation in linear form, and via this form, the standard enthalpies, entropies and Gibbs energies of sublimation and evaporation of compounds were calculated at 298.15 K. The standard molar formation enthalpies of compounds in crystalline state at 298.15 K were determined indirectly by the corresponding standard molar combustion enthalpy, obtained using bomb calorimetry combustion.

Conclusions

Determination of the thermodynamic properties for these compounds may contribute to solving practical problems pertaining optimization processes of their synthesis, purification and application and it will also provide a more thorough insight regarding the theoretical knowledge of their nature.Graphical abstract:

1-{5-[2-Chloro-5-(trifluoromethyl)phenyl]thiophen-2-yl}ethanone

In the title molecule, C₁₃H₈ClF₃OS, the dihedral angle between the mean planes of 2-chloro-5-(trifluoro­meth­yl)phenyl and tiophene rings is 54.37 (5)°. The acethyl group is twisted by 8.1 (2)° with respect to the thio­phene ring. The CF₃ group is disordered over two sets of sites with occupations of 0.49 (3) and 0.51 (3). The crystal packing features C—H⋯F and C—H⋯O hydrogen bonds, forming dimers which are connected into chains along the c axis by C—H⋯O hydrogen bonds and C—Cl⋯π [Cl⋯π = 3.415 (1) Å and C—Cl⋯π = 151.56 (5)°] inter­actions. The chains are further connected into layers perpendicular to the a axis by C—H⋯O inter­actions.

2-[(2Z,3E)-2-Hydroxyimino-5-phenyl-2,3-dihydro-3-thienylidene]-2-phenylacetonitrile

In the crystal structure of the title compound, C₁₈H₁₂N₂OS, centrosymmetric dimers are stabilized both by van der Waals inter­actions and by two types of inter­molecular O—H⋯N hydrogen bonds. In addition, an intra­molecular C—H⋯S hydrogen bond is observed. The dihedral angles between the central ring and the two pendant phenyl rings are 7.4 (1) and 45.06 (9)°.

3-(4-Chloro-phen-yl)-2,1-benzisoxazole-5-carbonyl chloride

The molecule of the title compound, C(14)H(7)Cl(2)NO(2), is not planar; the dihedral angle between the mean planes of the chloro-phenyl and benzisoxazole rings is 20.32 (7)°. The carbonyl chloride group is twisted with respect to the benzisoxazole ring by 2.5 (1)°. The mol-ecular conformation is stabilized by an intra-molecular C-H⋯Cl hydrogen bond. In the crystal packing, adjacent mol-ecules are linked into dimers by inter-molecular C-H⋯O hydrogen bonds. The dimers are further stacked into columns along the unique axis direction by π-π stacking inter-actions, with a centroid⋯centroid distance of 3.828 (5) Å. Other weak inter-molecular C-H⋯O and C-H⋯Cl inter-actions are also present.