Synthesis and Photophysical Properties of Monometallic C^C* Platinum(II) Formamidinate Complexes using Sterically Demanding Ligands.

A novel class of cyclometalated platinum(II) complexes-previously considered to be inaccessible-was synthesized by an improved synthetic route utilizing ligands predicted by density functional theory calculations. Based on a concise quantum chemical screening three model ligands with varying steric demand were chosen and a series of six photoluminescent C^C* cyclometalated platinum(II) formamidinate complexes was obtained. The least sterically demanding ligand led to a bimetallic complex in two isomeric forms, which could be separated and confirmed by the corresponding solid-state structures.

Electronic Structure and Magnetic Properties of a High-Spin Mn Complex: [Mn(mesacac) ] (mesacac=1,3-Bis(2,4,6-trimethylphenyl)-propane-1,3-dionato).

Metal acetylacetonates of the general formula [M(acac) ] (M =Cr, Mn, Fe, Co) are among the best investigated coordination compounds. Many of these first-row transition metal complexes are known to have unique electronic properties. Independently, photophysical research with different β-diketonate ligands pointed towards the possibility of a special effect of the 2,4,6-trimethylphenyl substituted acetylacetonate (mesacac) on the electron distribution between ligand and metal (MLCT).

Phosphorescent Bimetallic C^C* Platinum(ii) Complexes with Bridging Substituted Diphenylformamidinates.

A series of phosphorescent bimetallic platinum(II) complexes is presented, which were synthesized by the combination of bidentate cyclometalated N-heterocyclic carbene ligands and different bridging diphenylformamidinates. The complexes were characterized by standard techniques and additionally two solid-state structures could be obtained. Photoluminescence measurements revealed the strong emissive behavior of the compounds with quantum yields of up to 90 % and emission lifetimes of approx.

Cyclometalated Spirobifluorene Imidazolylidene Platinum(II) Complexes with Predominant LC Emissive Character and High Photoluminescence Quantum Yields.

Two novel bidentate C^C* cyclometalated platinum(II) complexes comprising a spiro-conjugated bifluorene ligand and different β-diketonate auxiliary ligands are synthesized and characterized. Their preparation employs a robust and elaborate synthetic protocol commencing with an -heterocyclic carbene precursor. Structural characterization by means of NMR techniques and solid-state structures validate the proposed and herein presented molecular scaffolds.

C^C* Platinum(II) Complexes with Electron-Withdrawing Groups and Beneficial Auxiliary Ligands: Efficient Blue Phosphorescent Emission.

The combination of strong electron-withdrawing groups in cyclometalated N-heterocyclic carbene ligands (C^C*) with known beneficial auxiliary ligands in phosphorescent platinum(II) complexes leads to efficient light-to-deep-blue emission with quantum yields of up to 92%. All compounds were characterized and investigated regarding their photophysical, electrochemical, and thermal properties, and three complexes could additionally be characterized by solid-state structures. Density functional theory calculations (PBE0/6-311G* with dispersion correction) are reported.

Platinum(II) Complexes with Bis(pyrazolyl)borate Ligands: Increased Molecular Rigidity for Bidentate Ligand Systems.

The structural motif of platinum(II) complexes bearing cyclometalating N-heterocyclic carbene ligands can be used to design deep-blue phosphors for application in organic light-emitting diodes. However, the photophysical properties of the resulting molecules are also highly dependent on the auxiliary ligand. These often allow molecular deformations in the excited state which contribute to non-radiative decay processes that diminish the attainable quantum yield.

Iron-Catalyzed Synthesis, Structure, and Photophysical Properties of Tetraarylnaphthidines.

We describe the synthesis and photophysical properties of tetraarylnaphthidines. Our synthetic approach is based on an iron-catalyzed oxidative C-C coupling reaction as the key step using a hexadecafluorinated iron-phthalocyanine complex as a catalyst and air as the sole oxidant. The ,,','-tetraarylnaphthidines proved to be highly fluorescent with quantum yields of up to 68%.