Stefan Steinbrecher

Applications of phthalocyanines in organic light emitting devices

Abstract Numerous experimental set-ups for organic light emitting devices including novel elaborate materials have been proposed during the last years. It is remarkable that in a large part of devices, phthalocyanines that are known for several decades are employed successfully in different functions. For this reason, a survey on the use of phthalocyanines in organic light emitting devices is provided. Owing to the great variety of device set-ups the findings of different working groups are not directly comparable in some cases. Nevertheless, it is shown that as a result of their advantageous physical properties phthalocyanines are a favourable choice for the increase in stability of such devices.

New Inorganic–Organic Hybrid Materials for HPLC Separation Obtained by Direct Synthesis in the Presence of a Surfactant

Nanostructured, mesoporous inorganic–organic hybrid xerogels were reproducibly synthesized by a sol–gel procedure. For the introduction of long alkyl chains into inorganic polymers, trifunctional n-alkyltrialkoxysilanes of the type CH3(CH2)nSi(OR)3 (n = 7, 11, 17; R = CH3, C2H5) were co-condensed with Si(OEt)4 (TEOS). The synthetic pathway involves the employment of n-hexadecylamine as template and catalyst. The xerogels obtained by the present procedure consist of uniform spherical particles with a diameter of about 1 μm. The composition of the new materials was determined by 13C and 29Si cross polarization magic angle spinning (CP/MAS) NMR spectroscopy. In addition, the degree of organization was investigated by small angle X-ray and electron diffraction. In accordance with 13C CP/MAS NMR spectroscopic measurements, the alkyl chains form a crystalline arrangement within the silica polymer. Brunauer–Emmett–Teller (BET) adsorption measurements confirm specific surface areas of up to 1400 m2/g. The material properties prove the xerogels to be suitable as stationary phases in high-performance liquid chromatography (HPLC). These novel mesoporous, nanostructured materials have been successfully employed in HPLC for the first time. Different standard reference materials (SRMs) containing polycyclic aromatic hydrocarbons have been separated with the xerogels described in the present work.

Synthesis, characterization and HPLC-applications of novel phthalocyanine modified silica gel materials

2(3)-Tetrakisalkenyloxy substituted phthalocyanines 3–6 are synthesized from the corresponding 1,2-dicyano-4-alkenyloxybenzenes 2a–c. These phthalocyanines were hydrosilylated with trimethoxysilane to yield the phthalocyanines 7–10 which were reacted immediately with tetramethoxysilane (TMOS) as co-condensation agent or HPLC silica gel to obtain the new stationary phases 11–16 based on phthalocyanines. The phthalocyanines 3–10 and the corresponding stationary phases 11–16 were characterized by MS, UV/Vis, IR, EA and NMR spectroscopy. Additionally, the stationary phase 16 was measured by suspended state NMR spectroscopy. With the PcInCl stationary phase 13c, scanning and transmission electron microscopic investigations were performed to obtain information about the morphology of the stationary phases. The modified HPLC silica gels 14–16 were tested successfully for the separation of two different aromatic test mixtures using methanol–water as eluent.

Accessibility Studies of Sol-Gel Processed Phosphane-Substituted Iridium(I) Complexes in the Interphase (‡)

The synthesis of the T-silyl functionalized, and therefore sol-gel processable, Vaska complex [IrCl(CO){(C6H5)2PC6H4(CH2)4Si(OMe)3}2] [4(T0)] succeeded by reaction of [Ir(μ-Cl)(COE)2]2 (COE = cyclooctene; 1) with the phosphane (C6H5)2PC6H4(CH2)4Si(OMe)3 [3(T0)] in the presence of carbon monoxide. Subsequently, 4(T0) was co-polycondensed with five equivalents of (MeO)3Si(CH2)3C6H4(CH2)3Si(OMe)3 {5[Ph(1,4-C3T0)2]} to give the polysiloxane-bound complex X1. For accessibility studies of the reactive centers, X1 was reacted in the interphase systems gas/solid and liquid/solid with HCl, Cl2, CH3I (13CH3I), Cl2HCCHCl2, SO2, O2, and NCC≡CCN, in the course of which the xerogels X2−X7 were formed. With the exception of the reversible species X5 (SO2) and X6 (O2) the reactions proceeded quantitatively. The composition of the polymers and the structures of the reactive centers were elucidated by means of multinuclear solid-state NMR (13C, 29Si, 31P), IR, EDX, and EXAFS spectroscopy.

Supported organometallic complexes. Part 27: novel sol–gel processed rhodium(I) complexes: synthesis, characterization, and catalytic reactions in interphases ☆

Abstract A novel T-silyl functionalized cationic (COD)(dppp)rhodium(I) complex was sol–gel processed with various amounts of the co-condensing agents MeSi(OMe) 2 (CH 2 ) 6 (OMe) 2 SiMe and MeSi(OMe) 2 (CH 2 ) 3 (C 6 H 4 )(CH 2 ) 3 (OMe) 2 SiMe to give novel stationary phases for ‘Chemistry in Interphases’. The polysiloxane matrices and the integrity of the rhodium(I) complex centers were investigated by means of multinuclear solid-state NMR ( 13 C, 29 Si, 31 P) and EXAFS spectroscopies. Dynamic NMR measurements show an increasing mobility of the matrix and the reactive centers with a higher amount of the co-condensing component. The accessibility of the anchored rhodium(I) centers was scrutinized by the metal catalyzed hydrogenation of 1-hexene. All applied xerogels show remarkable activities and selectivities. An enhancement of the activities is achieved when polar solvents are used. SEM micrographs reveal the morphology of the hybrid materials and energy dispersive X-ray spectroscopy (EDX) suggests that the distribution of the elements is in satisfying agreement with the applied composition.

Electrochemistry of transition metal complex catalysts. Part 8. One-electron oxidation of an iridium complex with a cyclohexane-derived tripod phosphine ligand - cyclic voltammetry and preparative electrolysis

Abstract The electrochemical oxidation of Ir(tdppcyme)(CO)Cl, tdppcyme= cis , cis -1,3,5-tris(di-phenylphosphine)- cis , cis -1,3,5-tris(methoxycarbonyl)cyclohexane, is investigated in dichloromethane–0.1 M tetrabutylammonium hexafluorophosphate at Pt electrodes with cyclic voltammetry, chronoamperometry and chronocoulometry, as well as preparative electrolysis. While the primary one-electron oxidation to Ir +II appears quasi-reversible in the electroanalytical experiments, the longer time scale of electrolysis allows the formation of an insoluble product by a follow-up reaction. By means of spectroscopic techniques as well as EXAFS and EDX experiments the structure of a dimeric di-μ-chloro di-iridium complex is deduced.

Accessibility and Solid State NMR Studies on Sol-Gel Processed Diphosphine Ligands

Novel xerogels X1 a–d were obtained by sol-gel processing of the monomeric T-functionalized diphosphine ligand (MeO)3Si(CH2)6CH[CH2PPh2]2[1(T0)] with various amounts of the co-condensing agents MeSi(OMe)2(CH2)6(OMe)2SiMe (D0–C6–D0) and MeSi(OMe)2(CH2)3(C6H4)(CH2)3(OMe)2SiMe [Ph(1,4-C3D0)2]. 29Si CP/MAS NMR spectroscopic investigations were applied to probe the matrices and their degree of condensation. The integrity of the hydrocarbon backbone and diphosphine moiety was examined by means of solid state NMR spectroscopy (13C, 31P). To study the dynamics of the matrices and the phosphorus centers detailed measurements of relaxation time (T1ρH) and cross polarization constants (TSiH, TPH) were carried out. The accessibility of the polysiloxane-supported diphosphines was scrutinized by some typical phosphine reactions. It was found that reagents such as H2O2, MeI as well as bulky molecules like (NBD)Mo(CO)4 or (COD)PdCl2 are able to reach all phosphorus centers independent on the kind of the backbone of the matrix. SEM micrographs show the morphology of the hybrid materials and energy dispersive X-ray spectroscopy (EDX) suggest that the distribution of the elements agree with the applied composition. Zuganglichkeits- und Festkorper-NMR-Studien an Sol-Gel-prozessierten Diphosphan-Liganden Die neuartigen Xerogele X1 a–d wurden durch Sol-Gel-Prozessierung des T-funktionalisierten Diphosphanliganden (MeO)3Si(CH2)6CH[CH2PPh2]2[1(T0)] mit unterschiedlichen Mengen der Cokondensationsmittel MeSi(OMe)2(CH2)6(OMe)2SiMe (D0–C6–D0) und MeSi(OMe)2(CH2)3(C6H4)(CH2)3(OMe)2SiMe [Ph(1,4-C3D0)2] erhalten. 29Si CP/MAS NMR-spektroskopische Untersuchungen liefern einen Einblick in den Aufbau der Matrices und ihrer Kondensationsgrade. Nach 13C- und 31P-Festkorper-NMR-spektroskopischen Untersuchungen gehen das Kohlenwasserstoffgerust und insbesondere die reaktiven Phosphanzentren aus dem Sol-Gel-Prozess unzersetzt hervor. Detaillierte Relaxationzeitmessungen (T1ρH) und Messungen der Kreuzpolarisationskonstanten (TSiH, TPH) geben Aufschluss uber die Dynamik der Matrices und Phosphorzentren. Mit typischen Phosphanreaktionen wurde die Zuganglichkeit der reaktiven Zentren uberpruft. Reagenzien wie H2O2 und MeI erreichen unabhangig vom Ruckgrat der Matrix die Phosphanzentren ebenso wie die sterisch anspruchsvollen Komplexe (NBD)Mo(CO)4 und (COD)PdCl2. SEM-Aufnahmen weisen auf die Morphologie der Hybridmaterialien hin. Energiedipersive rontgenspektroskopische Messungen (EDX) belegen die Elementzusammensetzung der neuen Materialien.

Electrochemistry of transition metal complex catalysts. Part 9. One-and two-electron oxidation of iridium complexes with cyclohexane-derived tripod phosphine ligands

The redox chemistry of Ir tripod-type tri-phosphine complexes in dichloromethane is investigated by cyclic voltammetry, hold-ramp experiments, and preparative electrolysis at Pt electrodes. Products are identified by spectroscopic data, as well as EDX and EXAFS results. Complexes with the Ir central atom in the oxidation states +I, +II and +III are detected and several follow-up reactions are possible from those. Most of the intermediates and products are characterized. In particular, experiments in the presence of CO contribute to the assignment of peaks in the cyclic voltammograms. The experimental results for the individual steps are summarized in a comprehensive redox reaction mechanism (mesh scheme) for which most steps are characterized by redox potentials.