Photophysical properties and OLED performance of light-emitting platinum(II) complexes.

The synthesis, photophysical properties and application as emitters in solution-processed multi-layer organic light-emitting diodes (OLEDs) of a series of blue-green to red light-emitting phosphorescent platinum(II) complexes are reported. These complexes consist of phenylisoquinoline, substituted phenylpyridines or tetrahydroquinolines as C^N cyclometalating ligands and dipivaloylmethane as an ancillary ligand. Depending on both the structure of the C^N cyclometalating ligands and the dopant concentration in the matrix, these platinum(II) complexes exhibit different aggregation tendencies. This property affects the photoluminescence spectra of the investigated compounds and colour-stability of the fabricated OLEDs. Using the blue-green to yellow-green emitting complexes, the best results were obtained with the 2-(4-trifluoromethylphenyl)-5,6,7,8-tetrahydroquinoline based platinum(II) complex. A maximum luminous efficiency of 4.88 cd A(-1) and a power efficiency of 4.65 lm W(-1), respectively, were achieved. Employing the red emitting phenylisoquinoline based complex as an emitter, colour-stable and efficient (4.71 cd A(-1), 5.12 lm W(-1)) devices were obtained.

Referenced dual pressure- and temperature-sensitive paint for digital color camera read out.

The first fluorescent material for the referenced simultaneous RGB (red green blue) imaging of barometric pressure (oxygen partial pressure) and temperature is presented. This sensitive coating consists of two platinum(II) complexes as indicators and a reference dye, each of which is incorporated in appropriate polymer nanoparticles. These particles are dispersed in a polyurethane hydrogel and spread onto a solid support. The emission of the (oxygen) pressure indicator, PtTFPP, matches the red channel of a RGB color camera, whilst the emission of the temperature indicator [Pt(II) (Br-thq)(acac)] matches the green channel. The reference dye, 9,10-diphenylanthracene, emits in the blue channel. In contrast to other dual-sensitive materials, this new coating allows for the simultaneous imaging of both indicator signals, as well as the reference signal, in one RGB color picture without having to separate the signals with additional optical filters. All of these dyes are excitable with a 405 nm light-emitting diode (LED). With this new composite material, barometric pressure can be determined with a resolution of 22 mbar; the temperature can be determined with a resolution of 4.3 °C.

Oxygen and temperature sensitivity of blue to green to yellow light-emitting Pt(II) complexes.

The synthesis and photophysical properties of a series of yellow-green to blue-green emitting heteroleptic, cyclometalated Pt(II)(acac) complexes based on substituted phenylpyridine and tetrahydroquinoline ligands is reported. The luminescence intensities and lifetimes of these compounds were also studied in poly(styrene) films with respect to their responses to oxygen and temperature. Particularly, due to the insensitivity to oxygen quenching, these complexes are promising candidates as inert reference dyes in optical sensors. On the other hand, the Pt(II) complex with 2-(4-bromophenyl)-5,6,7,8-tetrahydroquinoline as C^N ligand, displays a strong temperature quenching effect. The distinct response to temperature was additionally calibrated after incorporation in poly(vinylidene chloride-co-acrylonitrile) serving as oxygen-blocking matrix copolymer. The resulting yellow-green-emitting temperature sensor signifies an interesting alternative to the available mostly red emitting temperature-sensitive probes.

Determination of the relative ligand-binding strengths in heteroleptic Ir(III) complexes by ESI-Q-TOF tandem mass spectrometry.

An electrospray ionization quadrupole time-of-flight mass spectrometer has been utilized to investigate the relative ligand-binding strengths in a series of heteroleptic-charged iridium(III) complexes of the general formula [(C^N)(2) Ir(III) (S-tpy)](PF(6) ) by using variable collision energies. Collision-induced dissociation experiments were performed in order to study the stability of the Ir(III) complexes that are, for instance, suitable phosphors in light-emitting electrochemical cells. The ratio of signal intensities belonging to the fragment and the undissociated complex depends on the collision energy applied for the tandem mass spectra (MS/MS) analysis. By defining the threshold collision energy and the point of complete complex dissociation, it is possible to estimate the relative complex stabilities depending on the nature of the coordinated ligands [i.e. type of cyclometalating ligand (C^N), substituents on the S-shaped terpyridine (S-tpy)]. The collision energy values differed as a function of the coordination sphere of the Ir(III) centers.

Oligo(U-terpyridines) and their ruthenium(II) complexes: synthesis and structural properties.

A highly efficient domino reaction starting from tetrahydroquinolinone and a series of bisiminium salts provides the corresponding bis(U-terpyridines). These ligands have been treated with [(tpy)RuCl3] to afford novel dinuclear complexes [(tpy)Ru(L)Ru(tpy)]4+. The protocol is also applied for the synthesis of a star-shaped tris(U-terpyridine) and the trinuclear complex [{(tpy)Ru}3(L)]6+. In view of potential applications in the fields of metallopolymers and molecular devices, the electronic spectra, as well as the electrochemical potentials of all the complexes have been obtained. According to these data, no significant intermetal interaction has been observed for the ruthenium complexes presented here.

Selective synthesis of U-shaped terpyridines. Versatile ligands for the preparation of platinum complexes.

The development of a simple and highly selective method for the preparation of substituted U-shaped terpyridines is described. The treatment of imine 5 with ternary iminium salts 2 leads to the terpyridines 4. A possible mechanism is discussed. The terpyridine derivatives are used for the preparation of several platinum(II) complexes 14. Complex 14e is characterized by single-crystal X-ray analysis.

Modern Variants of the Mannich Reaction.

Important building blocks for the synthesis of drugs or natural products are found in Mannich bases and their derivatives. Modern variants of the Mannich reaction that expand the potential of the classical intermolecular reaction significantly and enable efficient control of the regioselectivity and stereoselectivity are therefore the topic of intensive research. Intramolecular reactions, in particular as part of domino reaction sequences, often afford astoundingly simple and elegant approaches to complex target compounds.