Editorial: 150 Years of the Technische Universität München: Innovation since 1868.

"… On Easter Sunday 1868, the decree founding the Polytechnische Hochschule München (today's Technische Universität München; TUM) was signed by the 23-year-old Ludwig II, King of Bavaria. Entrepreneurial spirit has been a hallmark of the TUM from the start, and it was the first German university to have a branch abroad. Interdisciplinary research is key, not least in the Department of Chemistry …" Read more in the Guest Editorial by Wolfgang A. Herrmann.

Macular hole surgery: an analysis of risk factors for the anatomical and functional outcomes with a special emphasis on the experience of the surgeon.

PURPOSE: The aim of this study was to evaluate risk factors for the anatomical and functional outcomes of macular hole (MH) surgery with special emphasis on the experience of the surgeon. METHODS: A total of 225 surgeries on idiopathic MHs (IMHs) performed by 6 surgeons with a mean follow-up period of 20.5 months were reviewed in this retrospective study. Outcome parameters focused on IMH closure, complications and visual acuity improvement. The results of MH surgeries performed by experienced surgeons were compared to those of surgeons in training. RESULTS: The average MH size was 381 µm (standard deviation [SD]=168). Brilliant blue G (BBG) for internal limiting membrane (ILM) staining was used in 109 (48%) eyes and indocyanine green (ICG) in 116 (52%) eyes. As endotamponade, 20% SF6 was used in 38 (17%) cases, 16% C2F6 in 33 (15%) cases and 16% C3F8 in 154 (68%) cases. IMH closure was achieved in 194 eyes (86%). Mean preoperative visual acuity was 0.84 logarithm of the minimum angle of resolution (log MAR; SD=0.29, range: 0.3-1.5); surgery led to a mean improvement of 0.40 (SD=0.37) log MAR. Although the MH closure rate was the same using BBG or ICG for ILM peeling, visual acuity improvement was better in eyes peeled with BBG compared to eyes peeled with ICG (log MAR: BBG: 0.38 [95% CI: 0.32, 0.44] vs ICG: 0.48 [95% CI: 0.42, 0.54], P=0.029). Surgeons with previous experience in vitreoretinal surgery of ≥6 years achieved better visual outcomes compared to surgeons with 0-3 years of experience, regardless of the MH size, preoperative visual acuity, time to follow-up or dye used for ILM peeling (0-3 years [0.27, Δlog MAR] vs ≥6 years [0.43, Δlog MAR], P=0.009). CONCLUSION: Our results indicate that vitrectomy with ILM peeling performed by non-experienced surgeons is a safe procedure leading to good anatomical and functional results. Very experienced surgeons may achieve even better functional outcomes.

Hydrogen Production and Storage on a Formic Acid/Bicarbonate Platform using Water-Soluble N-Heterocyclic Carbene Complexes of Late Transition Metals.

The synthesis and characterization of two water-soluble bis-N-heterocyclic carbene (NHC) complexes of rhodium and iridium is presented. Both compounds are active in H2 generation from formic acid and in hydrogenation of bicarbonate to formate. The rhodium derivative is most active in both reactions, reaching a TOF of 39 000 h-1 and a TON of 449 000 for H2 production. The catalytic hydrogenation reactions were carried out in an autoclave system and analyzed using the integrated peak areas in the 1 H NMR spectra. Decomposition of formic acid was investigated using a Fisher-Porter bottle equipped with a pressure transducer. Long-term stability for hydrogen evolution was tested by surveillance of the gas flow rate. The procedure does not require any additives like amines or inert gas conditions. Density functional theory calculations in agreement with experimental results suggest a bicarbonate reduction mechanism involving a second catalyst molecule, which provides an external hydride acting as reducing agent.

Olefin Epoxidation in Aqueous Phase Using Ionic-Liquid Catalysts.

Hydrophobic imidazolium-based ionic liquids (IL) act as catalysts for the epoxidation of unfunctionalized olefins in water using hydrogen peroxide as oxidant. Although the catalysts are insoluble in both the substrate and in water, surprisingly, they are very well soluble in aqueous H2 O2 solution, owing to perrhenate-H2 O2 interactions. Even more remarkably, the presence of the catalyst also boosts the solubility of substrate in water. This effect is crucially dependent on the cation design. Hence, the imidazolium perrhenates enable both the transfer of hydrophobic substrate into the aqueous phase, and serve as actual catalysts, which is unprecedented. At the end of the reaction and in absence of H2 O2 the IL catalyst forms a third phase next to the lipophilic product and water and can easily be recycled.

Immobilisation of a molecular epoxidation catalyst on UiO-66 and -67: the effect of pore size on catalyst activity and recycling.

Amino-functionalised metal-organic frameworks UiO-66 and -67 were post-synthetically modified with salicylaldehyde. A molybdenum complex was immobilised on the resulting materials. They were characterised by (13)C-MAS-NMR, XPS and PXRD to confirm immobilisation and stability. The immobilised complex is an active and reusable catalyst for olefin epoxidation with tert-butyl hydroperoxide (TBHP) as an oxidant. It is shown that the effective pore size, probed with Brunauer-Emmett-Teller (BET) surface area analysis and the number of amino groups affect the diffusion of reactants and products, as well as catalyst recycling.

Structure and spectroscopic properties of the dimeric copper(I) N-heterocyclic carbene complex [Cu2(CNC(t-Bu))2](PF6)2.

In recent years, the use of copper N-heterocyclic carbene (NHC) complexes has expanded to fields besides catalysis, namely medicinal chemistry and luminescence applications. In the latter case, multinuclear copper NHC compounds have attracted interest, however, the number of these complexes in the literature is still quite limited. Bis[µ-1,3-bis(3-tert-butylimidazolin-2-yliden-1-yl)pyridine]-1κ(4)C(2),N:N,C(2');2κ(4)C(2),N:N,C(2')-dicopper(I) bis(hexafluoridophosphate), [Cu2(C19H25N5)2](PF6)2, is a dimeric copper(I) complex bridged by two CNC, i.e. bis(N-heterocyclic carbene)pyridine, ligands. Each Cu(I) atom is almost linearly coordinated by two NHC ligands and interactions are observed between the pyridine N atoms and the metal centres, while no cuprophilic interactions were observed. Very strong absorption bands are evident in the UV-Vis spectrum at 236 and 274 nm, and an emission band is observed at 450 nm. The reported complex is a new example of a multinuclear copper NHC complex and a member of a compound class which has only rarely been reported.

Synthesis of cyclic carbonates from epoxides and carbon dioxide by using organocatalysts.

The synthesis of cyclic carbonates through coupling of carbon dioxide with epoxides is 100 % atom economical and is already performed on an industrial scale. Its impact regarding the use of carbon dioxide as a renewable carbon source is expected to grow significantly in the near future, so that the development of efficient catalysts is of high interest in academia and industry. To improve the carbon footprint and sustainability of the cycloaddition reaction, the use of organocatalytic methods is a promising approach. Herein, available metal-free catalysts for the preparation of cyclic carbonates are described and elaborated concerning the overall sustainability of the process. Therefore, the required reaction conditions, as well as the activity of the catalysts and their reusability, are compared and evaluated. In addition to ammonium-, phosphonium-, or imidazolium-based single-component catalysts and their supported analogues, the growing field of research concerning dual catalysts are also discussed in detail.

Direct Synthesis and Bonding Properties of the First µ(2)-η(2),η(2)-Allyl-Bridged Diiridium Complex.

The direct synthesis of the first µ(2)-η(2),η(2)-allyl-bridged diiridium complex ([2](+)), bearing the uncommon counterion [IrCl2(COD)](-) ([3](-)), is described. Both bridging moieties in [2](+), namely, allyl and acetate, are introduced in a single reaction step from [{IrCl(COD)}2] (1) and allyl acetate. A combination of X-ray crystallography and density functional theory calculations reveals pronounced metal-allyl π-back-bonding.

Influence of substituents on cation-anion contacts in imidazolium perrhenates.

A series of imidazolium perrhenates with different substituents at the imidazolium ring were synthesised and characterised, including single crystal X-ray diffraction. The effect of the substitution pattern on the state of aggregation of the compounds, the charge delocalisation and the ion pairing interaction via hydrogen bonds was studied. Particularly the substitution at the C2 position of the imidazolium ring was shown to be crucial to fine-tune the ion contacts. Fluorinated substituents appear to exhibit enhanced interionic interactions. The ability to tune the degree of contacts of the perrhenate anion allows for adjusting the nucleophilicity of this anion.

Catalytic epoxidation by perrhenate through the formation of organic-phase supramolecular ion pairs.

Organic-phase supramolecular ion pair (SIP) host-guest assemblies of perrhenate anions (ReO4(-)) with ammonium amide receptor cations are reported. These compounds act as catalysts for the epoxidation of alkenes by aqueous hydrogen peroxide under biphasic conditions and can be recycled several times with no loss in activity.

On the concept of hemilability: insights into a donor-functionalized iridium(I) NHC motif and its impact on reactivity.

Novel iridium(I) complexes bearing N-donor-functionalized N-heterocyclic carbene ligands were synthesized. Although hemilabile coordination of the attached donor is considered beneficial in catalysis, no detailed study of this phenomenon in these systems is available to date. The present report provides insight into the hemilabile bonding properties of a N,N'-bis(pyridin-2-yl)-imidazolylidene (NCN) ligand motif on iridium(I). In most cases, the presented compounds exhibit rare fluxional hemilabile coordination of the N donor, and remarkable performance in catalytic transfer hydrogenation is observed. Further, extensive reactivity studies often led to unexpected products.

Synthesis of the first radiolabeled 188Re N-heterocyclic carbene complex and initial studies on its potential use in radiopharmaceutical applications.

A novel approach towards the synthesis of radiolabeled organometallic rhenium complexes is presented. We successfully synthesized and analyzed the first (188)Re-labeled N-heterocyclic biscarbene complex, trans-dioxobis(1,1'-methylene-bis(3,3'-diisopropylimidazolium-2-ylidene))(188)rhenium(V) hexafluorophosphate ((188)Re-4) via transmetalation using an air-stable and moisture-stable silver(I) biscarbene complex. In order to assess the viability of this complex as a potential lead structure for in vivo applications, the stability of the (188)Re-NHC complex was tested in physiologically relevant media. Ultimately, our studies illustrate that the complex we synthesized dissociates rapidly and is therefore unsuitable for use in radiopharmaceuticals. However, it is clear that the transmetalation approach we have developed is a rapid, robust, and mild method for the synthesis of new (188)Re-labeled carbene complexes.

Catalytic hydroxylation of benzene and toluene by an iron complex bearing a chelating di-pyridyl-di-NHC ligand.

This work reports on iron-catalysed hydroxylation of benzene and toluene using aqueous H2O2. While benzene is hydroxylated with a high selectivity to phenol, toluene is hydroxylated to cresols with a high selectivity for the ortho and para-position. An inverse KIE indicates the presence of a high valent Fe=O species during catalysis.

Cycloaddition of carbon dioxide and epoxides using pentaerythritol and halides as dual catalyst system.

The combination of pentaerythritol with nucleophilic halide salts such as nBu4NI is used as a dual catalyst system for the cycloaddition of carbon dioxide (CO2) with a broad range of organic epoxides yielding the respective cyclic carbonates. Due to synergistic effects of the organocatalysts, excellent yields and selectivities could be achieved under mild reaction conditions. Moreover, the nontoxic, cost-efficient, and readily available system is easily recyclable without significant loss of reactivity, representing an exceptional sustainable approach for the fixation of CO2.

[Effect of silymarin on liver health and quality of life. Results of a non-interventional study]. / Einfluss von Silymarin auf Lebergesundheit und Lebensqualität.

BACKGROUND: Many drugs are known to have hepatotoxic side effects. The effect of silymarin on liver function and liver-injury-impaired quality of life under daily practice conditions in patients with elevated values of liver enzymes was evaluated in the present non-interventional study. METHOD: Patients with drug-induced elevated aminotransferase levels and indication for silymarin (Legalon forte) treatment for 2 to 3 months were documented prospectively over 4 months. At baseline, after 2 and 4 months, respectively, the following parameters were documented: alanine transaminase (ALT), aspartate transaminase (AST), γ-glutamyltransferase (GGT), alkaline phosphatase, total bilirubin, presence of liver-related skin symptoms and discoloured urine, severity of liver-related symptoms and quality of life. RESULTS: In total, 190 patients (53.2% male, median age 60.0 years [range 19-81]) from 48 centres participated in the non-interventional study. Among potentially hepatotoxic drugs, analgesics/anti-inflammatory drugs were used most frequently (45.8%). These drugs have been administered for a median period of 2.8 years (range 0.0-26.1). At baseline, all patients had elevated levels of ALT, AST or GGT. Fatigue, flatulence, upper abdominal discomfort, lethargy, and joint complaints were the most severe liver-related symptoms and prevalent in over 62% of patients. Quality of life was affected in 88.7% of patients. Significant reductions were achieved in all documented laboratory parameters (p < 0.001), leading to marked improvement in liver-related symptoms and increased quality of life already after 2 months. The percentage of patients with liver enzymes in the normal range increased considerably within 4 months. No adverse drug reactions were observed. CONCLUSIONS: Silymarin is a safe and efficacious treatment option for patients with elevated liver enzymes. A benefit in terms of liver-related symptoms as well as quality of life and performance was demonstrated already after 2 months of treatment.

Synthesis and characterisation of chelated cationic ReI(CO)3bis(NHC)(WCA) complexes.

Twelve novel Re(I) acetonitrile complexes of the type [Re(CO)3(L)(MeCN)][WCA], with L being a chelating bis(NHC) ligand with alkylene-bridged and N-substituted bis(imidazolineylidene) moieties, and WCA (WCA = weakly coordinating anion) representing PF6(-) and [Al(OC(CF3)3)4](-), have been synthesized. 1D and 2D NMR spectroscopy as well as IR spectroscopy, elemental analysis and X-ray crystallography have been applied in characterization. The propylene-bridged complex, displaying mesitylene groups R, is discussed in depth revealing interesting chemical behaviour both in solid state and in solution. DFT calculations were undertaken to better understand the properties of such compounds. In addition, the X-ray molecular structure of the first rhenium CCC pincer complex is reported.

Synthesis and comparison of transition metal complexes of abnormal and normal tetrazolylidenes: a neglected ligand species.

To date, only few examples of tetrazolylidene carbenes coordinated to transition metal complexes have been described. A direct comparison of "normal" tetrazolylidenes (1,4-substitution pattern) and "abnormal" tetrazolylidenes (also referred to as "mesoionic carbenes"; 1,3-substitution pattern) has not been performed at all. In this work, we describe coordination of both ligand types to a row of transition metals. For example, the first examples of tetrazolylidene Mo, Ag, or Ir complexes have been isolated and fully characterized. The mesoionic tetrazolylidene Ag compound 2d is shown to be a viable carbene transfer reagent. By means of NMR, IR, and Raman spectroscopy, as well as X-ray crystallography and computational results, the pronounced differences between the two ligand substitution patterns are highlighted. It is shown that simply changing the position of a methyl group from N3 to N4 in the heterocycle can cause enormous differences in ligand characteristics.

Exploring the scope of a novel ligand class: synthesis and catalytic examination of metal complexes with 'normal' 1,2,3-triazolylidene ligands.

Using new 'normal'-substituted 1,2,3-triazolylidene silver compounds as starting materials allowed for preparation of a series of molybdenum, ruthenium, rhodium, and palladium transition metal complexes bound to the new 1,2,3-triazolylidene ligand system. In this work, the first triazolylidene Mo compound is presented as well as the first structural investigation of a silver complex with a monodentate 1,2,3-triazolylidene. Furthermore, the triazolylidene Pd complex and the Mo complex were tested as precatalysts in Suzuki-Miyaura coupling and epoxidation catalysis, respectively.