Iron(III) Carbene Complexes with Tunable Excited State Energies for Photoredox and Upconversion.

Substituting precious elements in luminophores and photocatalysts by abundant first-row transition metals remains a significant challenge, and iron continues to be particularly attractive owing to its high natural abundance and low cost. Most iron complexes known to date face severe limitations due to undesirably efficient deactivation of luminescent and photoredox-active excited states. Two new iron(III) complexes with structurally simple chelate ligands enable straightforward tuning of ground and excited state properties, contrasting recent examples, in which chemical modification had a minor impact.

Reversible Photoinduced Ligand Substitution in a Luminescent Chromium(0) Complex.

Light-triggered dissociation of ligands forms the basis for many compounds of interest for photoactivated chemotherapy (PACT), in which medicinally active substances are released or "uncaged" from metal complexes upon illumination. Photoinduced ligand dissociation is usually irreversible, and many recent studies performed in the context of PACT focused on ruthenium(II) polypyridines and related heavy metal complexes. Herein, we report a first-row transition metal complex, in which photoinduced dissociation and spontaneous recoordination of a ligand unit occurs.

Luminescence and Excited-State Reactivity in a Heteroleptic Tricyanido Fe(III) Complex.

Harnessing sunlight via photosensitizing molecules is key for novel optical applications and solar-to-chemical energy conversion. Exploiting abundant metals such as iron is attractive but becomes challenging due to typically fast nonradiative relaxation processes. In this work, we report on the luminescence and excited-state reactivity of the heteroleptic [Fe(pzTp)(CN)] complex (pzTp = tetrakis(pyrazolyl)borate), which incorporates a σ-donating trispyrazolyl chelate ligand and three monodentate σ-donating and π-accepting cyanide ligands.

A CuCo cryptate for the visible light-driven reduction of CO.

Among the rare bimetallic complexes known for the reduction of CO, CoCo and ZnCo hexamine cryptates are described as efficient photocatalysts. In close relation to the active sites of natural, CO-reducing enzymes, we recently reported the asymmetric cryptand {NN} ({NN} = N[(CH)SCH(-CH)CHNH(CH)]N) comprising distinct sulphur- and nitrogen-rich binding sites and the corresponding CuM (M = Co, Ni, Cu) complexes. To gain insight into the effect of metals in different oxidation states and sulphur-incorporation on the photocatalytic activity, we herein investigate the CuCo complex of {NN} as catalyst for the visible light-driven reduction of CO.

Visible-Light-Driven CO Reduction with Homobimetallic Complexes. Cooperativity between Metals and Activation of Different Pathways.

Visible-light-driven reduction of CO to both CO and formate (HCOO) was achieved in acetonitrile solutions using a homobimetallic Cu bisquaterpyridine complex. In the presence of a weak acid (water) as coreactant, the reaction rate was enhanced, and a total of ca. 766 TON (turnover number) was reached for the CO reduction, with 60% selectivity for formate and 28% selectivity for CO, using Ru(phen) as a sensitizer and amines as sacrificial electron donors.

A machine-learning tool to predict substrate-adaptive conditions for Pd-catalyzed C-N couplings.

Machine-learning methods have great potential to accelerate the identification of reaction conditions for chemical transformations. A tool that gives substrate-adaptive conditions for palladium (Pd)-catalyzed carbon-nitrogen (C-N) couplings is presented. The design and construction of this tool required the generation of an experimental dataset that explores a diverse network of reactant pairings across a set of reaction conditions.

Organophotocatalytic Aerobic Oxygenation of Phenols in a Visible-Light Continuous-Flow Photoreactor.

A mild photocatalytic phenol oxygenation enabled by a continuous-flow photoreactor using visible light and pressurized air is described herein. Products for wide-ranging applications, including the synthesis of vitamins, were obtained in high yields by precisely controlling principal process parameters. The reactor design permits low organophotocatalyst loadings to generate singlet oxygen.

The radiological diagnosis of cerebral venous angioma: cerebral angiography and computed tomography.

The angiographic and CT findings in seven cases of cerebral venous angioma are presented and analyzed. Two cases were also examined with dynamic CT. The radiological literature on the subject is reviewed and a new classification of cerebral venous angioma based on its pattern of drainage is proposed.

[Ultrasound-controlled fine needle puncture of gastrointestinal tumors with continuous view].

On account of its principle, ultrasound tomography cannot be recommended as a screening method for intestinal tumors; nevertheless, it may sometimes demonstrate larger tumors not producing typical signs. These neoplasms show a characteristic pattern ("cockade phenomenon"). In the region of the antrum they appear occasionally as a rigid thickening of the gastric wall.

The current state of the radiological diagnosis of acoustic neuroma.

Thin, overlapping section, contrast-enhanced, axial and coronal CT, with additional high-resolution (HR) treatment of the sections through the internal auditory canal, was performed on 31 patients clinically suspected of acoustic neuroma. With this technique 13 acoustic neuromas protruding more than 10 mm and eight acoustic neuromas protruding between 2 and 10 mm outside the internal auditory canal were unequivocally diagnosed. O2CT cisternography was performed on ten patients.

Intramural pseudodiverticulosis of the esophagus: report of seven cases and literature review.

Seven cases of esophageal intramural pseudodiverticulosis (EIPD) are presented and compared with 46 cases previously reported. EIPD is mainly a disease of older age with a 3:2 predominance of male patients. The radiologic appearance of EIPD shows great variation in localization and severity of visible changes.

[Experience with sonographically controlled fine-needle punctures with permanent visual control (author's transl)].

With our new biopsy-device it is now possible to perform fine-needle punctures of lesions in the abdomen, thoracic cage, cervical region and extremities under continuous visual control. This intervention can easily be done with low risk for the patient and can be repeated whenever necessary. It has proven its advantages for amniocentesis as well, especially in cases with a low amount of amniotic fluid.

[Correlation the laevocardiogram and plain chest films in the presence of myocardial insufficiency (author's transl)].

A correlation was attempted in 106 patients with myocardial insufficiency between linear and volume parameters of the laevocardiogram and the corresponding parameters on plain chest films, as well as between pressure measurements and the degree of pulmonary congestion. Measurements on the plain radiograph provide only limited information on the function of the myocardium and the severity of myocardial lesion respectively. Nevertheless, they are of some value during the course of the disease.

Computed tomography of acoustic neuromas with emphasis on small tumor detectability.

The results of CT analysis of 41 acoustic neuromas are presented. Large and medium-sized tumors are easily detected: our results are comparable to the reported findings of other authors. The detectability of small acoustic neuromas is considerably improved by the application of newer-generation CT apparatus and the use of specific scanning parameters, including extremely thin overlapping slices, low scan speed, high gantry tilt, short time between contrast agent application and tumor scanning, and computer-assisted magnification of the posterior fossa.

[Abeurysm of the septum membranaceum].

Between 1968 and 1977 5000 angiocardiographies revealed an aneurysm of the membranous septum (AMS) in 20 patients. In 11 patients the AMS was accompanied by a usually minor ventricular septal defect, in 4 by aortic valve disease, in 3 by coronary heart disease and in the remainder by some other rare heart disease. The diagnosis of AMS was established by angiocardiography, but in 3 patients it was detected by echocardiography.

[Possibilities and limits of xeroradiography. A statement (author's transl)].

Xeroradiography has proved to be of particular use for the examination of soft tissues. Due to great latitude and edge enhancement effect alterations of the splanchnocranium, the breast and the juxtaosseous soft tissues are especially well recognizable. Also for examination of larynx and trachea as well as certain soft tissues in the region of the neck this method is advantageous and proves its facilities to demonstrate diseases of the lungs and hilar region.