Highly Efficient Phosphorescent Blue-Emitting [3+2+1] Coordinated Iridium (III) Complex for OLED Application

Cyclometalated iridium (III) complexes are indispensable in the field of phosphorescent organic light-emitting diodes (PhOLEDs), while the improvement of blue iridium (III) complexes is as yet limited and challenging. More diversified blue emitters are needed to break through the bottleneck of the industry. Hence, a novel [3+2+1] coordinated iridium (III) complex (noted as Ir-dfpMepy-CN) bearing tridentate bis-N-heterocyclic carbene (NHC) chelate (2,6-bisimidazolylidene benzene), bidentate chelates 2-(2,4-difluorophenyl)-4-methylpyridine (dfpMepy), and monodentate ligand (-CN) has been designed and synthesized. The tridentate bis-NHC ligand enhances molecular stability by forming strong bonds with the center iridium atom. The electron-withdrawing groups in the bidentate ligand (dfpMepy) and monodentate ligand (-CN) ameliorate the stability of the HOMO levels. Ir-dfpMepy-CN shows photoluminescence peaks of 440 and 466 nm with a high quantum efficiency of 84 ± 5%. Additionally, the HATCN (10 nm)/TAPC (40 nm)/TcTa (10 nm)/10 wt% Ir-dfpMepy-CN in DPEPO (10 nm)/TmPyPB (40 nm)/Liq (2.5 nm)/Al (100 nm) OLED device employing the complex shows a CIE coordinate of (0.16, 0.17), reaching a deeper blue emission. The high quantum efficiency is attributed to rapid singlet to triplet charge transfer transition of 0.9–1.2 ps. The successful synthesis of Ir-dfpMepy-CN has opened a new window to develop advanced blue emitters and dopant alternatives for future efficient blue PhOLEDs.

Molecular and Supramolecular Structures of Cd(II) Complexes with Hydralazine-Based Ligands; A New Example for Cyclization of Hydrazonophthalazine to Triazolophthalazine

Molecular and supramolecular structures of two polymeric and one trinuclear Cd(II) complex with hydralazine-type ligands were presented. Self-assembly of E-1-(2-(thiophen-2-ylmethylene)hydrazinyl)phthalazine (HL) and CdCl2 gave the 1D coordination polymer [Cd(H2L)Cl3]n*H2O, 1, in which the Cd(II) ion is hexa-coordinated with one cationic monodentate ligand (H2L+) and five chloride ions, two of them acting as connectors between Cd(II) centers, leading to the formation of a 1D coordination polymer along the a-direction. Using DFT calculations, the cationic ligand (H2L+) could be described as a protonated HL with an extra proton at the hydrazone moiety. Repeating the same reaction by heating under reflux conditions in the presence of 1 mL saturated aqueous KSCN solution, the ligand HL underwent cyclization to the corresponding [1,2,4]triazolo[3,4-a]phthalazine-3(2H)-thione (TPT) followed by the formation of [Cd(TPT)(SCN)2]n*H2O, 2, a 1D coordination polymer. In this complex, the Cd(II) is coordinated with one NS-donor TPT bidentate chelate and two bridged μ(1,3)-thiocyanate ions connecting the Cd(II) centers forming the 1D polymer array along the b-direction. Heating E-2-(1-(2-(phthalazin-1-yl)hydrazono)ethyl)phenol HLOH with CdCl2 under reflux condition gave the trinuclear complex [Cd3(Hydralazine)2(H2O)2Cl6], 3, indicating the hydrolysis of the hydrazonophthalazine ligand HLOH during the course of the reaction. Due to symmetry considerations, there are only two different Cd(II) centers having CdN2Cl3O and CdN2Cl4 coordination environments. Hirshfeld topology analysis was used to analyze the solid-state supramolecular structure of the studied complexes.

A New Photoactivatable Ruthenium(II) Complex with an Asymmetric Bis-Thiocarbohydrazone: Chemical and Biological Investigations

The synthesis, photoactivation and biological activity of a new piano-stool Ru(II) complex is herein reported. The peculiarity of this complex is that its monodentate ligand which undergoes the photodissociation is an asymmetric bis-thiocarbohydrazone ligand that possesses a pyridine moiety binding to Ru(II) and the other moiety contains a quinoline that endows the ligand with the capacity of chelating other metal ions. In this way, upon dissociation, the ligand can be released in the form of a metal complex. In this article, the double ability of this new Ru(II) complex to photorelease the ligand and to chelate copper and nickel is explored and confirmed. The biological activity of this compound is studied in cell line A549 revealing that, after irradiation, proliferation inhibition is reached at very low half maximal inhibitory concentration (IC50) values. Further, biological assays reveal that the dinuclear complex containing Ni is internalized in cells.

Thermal hysteresis induced by external pressure in a 3D Hofmann-type SCO-MOF

Two isostructural 3D Hofmann-type frameworks, [FeII(dbdpe)MII(CN)4]·4H2O (M = Pt for 1 and Pd for 2), were synthesized based on a bis-monodentate ligand dbdpe (1,2-dibromo-1,2-di(pyridin-4-yl)ethane). Both compounds underwent similar one-step incomplete...

Syntheses and crystal structures of solvate complexes of alkaline earth and lanthanoid metal iodides with N,N-dimethylformamide

The solvate complexes that can be obtained by either dissolving metal iodides in N,N-dimethylformamide (DMF) or by synthesising them in DMF have the general composition [M(DMF)x]Iy. DMF shows to behave as simple monodentate ligand with low sterical impact, so that x in the composition follows the radius of My+. We present here the crystal structures of the alkaline earth and lanthanoid metal iodide complexes [Mg(DMF)6]I2, [Ca(DMF)6]I2, [Sr(DMF)7]I2, [Ba(DMF)8]I2, [La(DMF)9]I3, [Ln(DMF)8]I3 (isotypic series for Ln = Nd, Sm, Eu, Dy, Gd, Er, Yb and Lu) and for the tris-triiodide complex salt [Sc(DMF)6](I3)3. Their different crystal structure types can be compared on the basis of the packing topologies of the nearly spherical cationic entities which show simple sphere packing motifs.

Tetrakis[μ2-5-nitro-2-(phenylsulfanyl)benzoato-κ2 O:O′]bis[(acetonitrile-κN)copper(II)]

The title compound, [Cu2(μ2-O2CC12H8NO2S)4(CH3CN)2], consists of a dinuclear and centrosymmetric complex based on two CuII atoms coordinated by four 5-nitro-2-phenylsulfanyl-benzoate anions and two acetonitrile ligands. Each benzoate anion acts as a bis-monodentate ligand while each acetonitrile acts as a monodentate ligand, leading to a square-pyramidal NO4 coordination environment for each CuII atom with the acetonitrile N atom at the apex. The intramolecular Cu...Cu distance in the dimer is 2.6478 (3) Å. The cohesion of the crystal structure is ensured by (phenyl)C—H...O(nitro) hydrogen bonds and (phenyl)C—H...π interactions.

Supersilyl as an effective monodentate ligand to stabilize four-coordinate manganese(ii) complexes

Supersilyl, –Si(SiMe3)3, serves as an effective ligand to afford a series of four-coordinate manganese(ii) complexes.

Interactions of Metal ions withTrimethoprim and Metformin

In this work, metal complexes of trimethoprim mixed metformin were synthesized and characterized by solubility studies, percentage metal analysis, UV-Vis spectroscopy, IR spectroscopy and magnetic susceptibility and conductivity measurements. The IR spectra showedthat the trimethoprim coordinated as a monodentate ligand coordinating to the metal ions via the pyrimidine N(1), metformin acts as a bidentate ligand coordinating through the iminonitrogens. The infrared spectra bands at 450 cm-1 and 530 cm-1 is ascribed to M –N and M –O bond respectively indicating the formation of these complexes. The magnetic moment data showed that all the complexes were paramagnetic with values ranging from 1.39 to 6.0 B.M, except [Zn(TMP)(MET)(H2O)Cl2] which was diamagnetic. The conductivity results revealed that all the synthesised complexes were non-electrolytes, while the antibacterial studies of the mixed ligand complexes displayed moderate antimicrobial activity in comparison with the free ligands.