Visible Light-Induced Regioselective Intermolecular [2 + 2]-Cycloaddition of Alkyne and 2(1H)-Quinolone Derivatives.

We have developed a visible light-induced intermolecular [2 + 2]-cycloaddition reaction between alkenes and alkynes using thioxanthone and Cu(OTf)2 as cocatalysts. Various quinolin-2(1H)-ones, featuring diverse substituted groups, were successfully employed in this reaction, resulting in the synthesis of a series of 4,8b-dihydrocyclobuta[c]quinolin-3(2aH)-ones. Our methodology presents a novel synthetic approach for alkene-alkyne [2 + 2]-cycloaddition, delivering cyclobutene derivatives with exceptional regioselectivity.

Recyclable N-Heterocyclic Carbene Porous Coordination Polymers with Two Distinct Metal Sites for Transformation of CO2 to Cyclic Carbonates.

Single-component catalysts with integrated multiple reactive centers could work in concert to achieve enhanced activity tailored for specific catalytic reactions, but they remain underdeveloped. Herein, we report the construction of heterogeneous bimetallic porous coordination polymers (PCPs) containing both porphyrin and N-heterocyclic carbene (NHC) metal sites via the coordinative assembly of the NHC functionalities. Three heterobimetallic PCPs (TIPP-Zn-Pd, TIPP-Cu-Pd and TIPP-Ni-Pd) have been prepared to verify this facile synthetic strategy for the first time. In order to establish a cooperative action toward the catalytic CO2 cycloaddition with epoxides, an additional tetraalkylammonium bromide functionality has also been incorporated into these polymeric structures through the N-substituent of the NHC moieties. The resulting heterogeneous bimetallic catalyst TIPP-Zn-Pd exhibits the best catalytic performance in CO2 cycloaddition with styrene oxide (SO) under solvent-free conditions at atmospheric pressure and is applicable to a wide range of epoxides. More importantly, TIPP-Zn-Pd works smoothly and is recyclable in the absence of a cocatalyst under 1.0 MPa of CO2 at 60 °C. This indicates that TIPP-Zn-Pd is quite competitive with the reported heterogeneous catalysts, which typically require a high reaction temperature above 100 °C under cocatalyst-free conditions. Thus, this work provides a new approach to design heterogeneous bimetallic PCP catalysts for high-performance CO2 fixation under mild reaction conditions.

Cyclic iron tetra N-heterocyclic carbenes: synthesis, properties, reactivity, and catalysis.

Cyclic iron tetracarbenes are an emerging class of macrocyclic iron N-heterocyclic carbene (NHC) complexes. They can be considered as an organometallic compound class inspired by their heme analogs, however, their electronic properties differ, e.g. due to the very strong σ-donation of the four combined NHCs in equatorial coordination. The ligand framework of iron tetracarbenes can be readily modified, allowing fine-tuning of the structural and electronic properties of the complexes. The properties of iron tetracarbene complexes are discussed quantitatively and correlations are established. The electronic nature of the tetracarbene ligand allows the isolation of uncommon iron(III) and iron(IV) species and reveals a unique reactivity. Iron tetracarbenes are successfully applied in C-H activation, CO2 reduction, aziridination and epoxidation catalysis and mechanisms as well as decomposition pathways are described. This review will help researchers evaluate the structural and electronic properties of their complexes and target their catalyst properties through ligand design.

What has Kant got to say about conscientious objection to reproductive health in South Africa?

A woman's right to a safe legal abortion in South Africa conflicts with a health care professional's freedom of conscience. Conscientious objection or treatment refusal on the basis of conscience may be protected by the constitution but its morality has not been explored. This study uses Kantian Deontology to elucidate the ethical duties of health care professionals based on the Physician's Pledge. It concludes that conscience is morally empty and that health care professionals have a duty to treat all patients equally irrespective of the condition they present. Drawing on Kantian promise keeping, the study also concludes that health care professionals should place patients health and wellbeing above all other considerations. Using the categorical imperative, the study shows that health care professionals have a perfect duty not to refuse treatment. The study recommends that conscientious objection be rejected in all circumstances except where the psychological wellbeing of the health care professional will be affected. This can be achieved through legislative and professional body regulation of conscientious objection.

Transition-Metal-Free Synthesis of Functionalized Quinolines by Direct Conversion of ß-O-4 Model Compounds.

Direct production of heterocyclic aromatic compounds from lignin ß-O-4 models remains a huge challenge due to the incompatible catalysis for aryl ether bonds cleavage and heterocyclic ring formation. Herein, the first example of quinoline synthesis from ß-O-4 model compounds by a one-pot cascade reaction is reported in yields up to 89 %. The reaction pathway involves selective cleavage of C-O bonds, dehydrogenation, aldol condensation, C-N bond formation along with heterocyclic aromatic ring construction. The control experiments suggest that both imine and chalcone were identified as the key intermediates, and the rate determining step as well as the preferred pathway were experimentally clarified and supported by density functional theory (DFT) calculations. Based on this protocol, the conversion of ß-O-4 polymer delivered 56 wt % yield of quinoline derivative in three steps. This transformation provides a potential petroleum-independent choice for heterocyclic aromatic chemicals.

Activation of Molecular Oxygen by a Cobalt(II) Tetra-NHC Complex*.

The first dicobalt(III) µ2 -peroxo N-heterocyclic carbene (NHC) complex is reported. It can be quantitatively generated from a cobalt(II) compound bearing a 16-membered macrocyclic tetra-NHC ligand via facile activation of dioxygen from air at ambient conditions. The reaction proceeds via an end-on superoxo intermediate as demonstrated by EPR studies and DFT. The peroxo moiety can be cleaved upon addition of acetic acid, yielding the corresponding CoIII acetate complex going along with H2 O2 formation. In contrast, both CoII and CoIII complexes are also studied as catalysts to utilize air for olefin and alkane oxidation reactions; however, not resulting in product formation. The observations are rationalized by DFT-calculations, suggesting a nucleophilic nature of the dicobalt(III) µ2 -peroxo complex. All isolated compounds are characterized by NMR, ESI-MS, elemental analysis, EPR and SC-XRD.

Decision making in the end-of-life care of patients who are terminally ill with cancer - a qualitative descriptive study with a phenomenological approach from the experience of healthcare workers.

BACKGROUND: In Colombia, recent legislation regarding end-of-life decisions includes palliative sedation, advance directives and euthanasia. We analysed which aspects influence health professionals´ decisions regarding end-of-life medical decisions and care for cancer patients. METHODS: Qualitative descriptive-exploratory study based on phenomenology using semi-structured interviews. We interviewed 28 oncologists, palliative care specialists, general practitioners and nurses from three major Colombian institutions, all involved in end-of-life care of cancer patients: Hospital Universitario San Ignacio and Instituto Nacional de Cancerología in Bogotá and Hospital Universitario San José in Popayan. RESULTS: When making decisions regarding end-of-life care, professionals consider: 1. Patient's clinical condition, cultural and social context, in particular treating indigenous patients requires special skills. 2. Professional skills and expertise: training in palliative care and experience in discussing end-of-life options and fear of legal consequences. Physicians indicate that many patients deny their imminent death which hampers shared decision-making and conversations. They mention frequent ambiguity regarding who initiates conversations regarding end-of-life decisions with patients and who finally takes decisions. Patients rarely initiate such conversations and the professionals normally do not ask patients directly for their preferences. Fear of confrontation with family members and lawsuits leads healthcare workers to carry out interventions such as initiating artificial feeding techniques and cardiopulmonary resuscitation, even in the absence of expected benefits. The opinions regarding the acceptability of palliative sedation, euthanasia and use of medications to accelerate death without the patients´ explicit request vary greatly. 3. Conditions of the insurance system: limitations exist in the offer of oncology and palliative care services for important proportions of the Colombian population. Colombians have access to opioid medications, barriers to their application are largely in delivery by the health system, the requirement of trained personnel for intravenous administration and ambulatory and home care plans which in Colombia are rare. CONCLUSIONS: To improve end-of-life decision making, Colombian healthcare workers and patients need to openly discuss wishes, needs and care options and prepare caregivers. Promotion of palliative care education and development of palliative care centres and home care plans is necessary to facilitate access to end-of-life care. Patients and caregivers' perspectives are needed to complement physicians' perceptions and practices.

Medical decisions concerning the end of life for cancer patients in three Colombian hospitals - a survey study.

BACKGROUND: Cancer patients' end-of-life care may involve complex decision-making processes. Colombia has legislation regarding provision of and access to palliative care and is the only Latin American country with regulation regarding euthanasia. We describe medical end-of-life decision-making practices among cancer patients in three Colombian hospitals. METHODS: Cancer patients who were at the end-of-life and attended in participating hospitals were identified. When these patients deceased, their attending physician was invited to participate. Attending physicians of 261 cancer patients (out of 348 identified) accepted the invitation and answered a questionnaire regarding end-of-life decisions: a.) decisions regarding the withdrawal or withholding of potentially life-prolonging medical treatments, b.) intensifying measures to alleviate pain or other symptoms with hastening of death as a potential side effect, and c.) the administration, supply or prescription of drugs with an explicit intention to hasten death. For each question addressing the first two decision types, we asked if the decision was fully or partially made with the intention or consideration that it may hasten the patient's death. RESULTS: Decisions to withdraw potentially life-prolonging treatment were made for 112 (43%) patients, 16 of them (14%) with an intention to hasten death. For 198 patients (76%) there had been some decision to not initiate potentially life-prolonging treatment. Twenty-three percent of patients received palliative sedation, 97% of all patients received opioids. Six patients (2%) explicitly requested to actively hasten their death, for two of them their wish was fulfilled. In another six patients, medications were used with the explicit intention to hasten death without their explicit request. In 44% (n = 114) of all cases, physicians did not know if their patient had any advance care directives, 26% (n = 38) of physicians had spoken to the patient regarding the possibility of certain treatment decisions to hasten death where this applied. CONCLUSIONS: Decisions concerning the end of life were common for patients with cancer in three Colombian hospitals, including euthanasia and palliative sedation. Physicians and patients often fail to communicate about advance care directives and potentially life-shortening effects of treatment decisions. Specific end-of-life procedures, patients' wishes, and availability of palliative care should be further investigated.

Identifying Regional Viscoelastic Properties of the Superficial Muscular Aponeurotic System.

BACKGROUND: Suspension of the superficial muscular aponeurotic system (SMAS) is generally believed to be necessary in facelift surgery. Although many techniques have been suggested, all rely on the viscoelastic properties of the SMAS. OBJECTIVES: The aim of this study was to determine the viscoelastic properties of bursting strength, stress relaxation, and creep in the lateral, mid-cheek, and medial regions of the SMAS. METHODS: The viscoelastic properties of the SMAS were determined in 12 cadaveric hemifaces. Lateral SMAS was classified as the SMAS overlying the parotid gland; mid-cheek SMAS as anterior to the parotid and overlying the masseter muscle; and medial SMAS as including tissue extending medial from the lateral canthus and ending at the nasolabial fold. RESULTS: The 3 SMAS regions showed significantly different bursting strengths: 38.9 N for the lateral SMAS, 26.7 N for the mid-cheek SMAS, and 11.9 N for the medial SMAS (P < 0.0001). Stress relaxation was similar in all vertical regions with measurements of 54% in the lateral, 48% in the mid-cheek, and 59% in the medial SMAS. Creep was found to be similar in the lateral and mid-cheek SMAS with values of 18% and 19%, respectively. The medial SMAS was noted to have a higher creep at 22%. CONCLUSIONS: The lateral SMAS has a stronger bursting strength than the mid-cheek and medial SMAS. Creep appears to be lower in the lateral and mid-cheek SMAS. Stress relaxation appears to be similar in all 3 vertical regions.

Sustainable Production of Benzylamines from Lignin.

Catalytic conversion of lignin into heteroatom functionalized chemicals is of great importance to bring the biorefinery concept into reality. Herein, a new strategy was designed for direct transformation of lignin ß-O-4 model compounds into benzylamines and phenols in moderate to excellent yields in the presence of organic amines. The transformation involves dehydrogenation of Cα -OH, hydrogenolysis of the Cß -O bond and reductive amination in the presence of Pd/C catalyst. Experimental data suggest that the dehydrogenation reaction proceeds over the other two reactions and secondary amines serve as both reducing agents and amine sources in the transformation. Moreover, the concept of "lignin to benzylamines" was demonstrated by a two-step process. This work represents a first example of synthesis of benzylamines from lignin, thus providing a new opportunity for the sustainable synthesis of benzylamines from renewable biomass, and expanding the products pool of biomass conversion to meet future biorefinery demands.

Linking Low-Coordinate Ge(II) Centers via Bridging Anionic N-Heterocyclic Olefin Ligands.

We introduce a large-scale synthesis of a sterically encumbered N-heterocyclic olefin (NHO) and illustrate the ability of its deprotonated form to act as an anionic four-electron bridging ligand. The resulting multicenter donating ability has been used to link two low oxidation state Ge(II) centers in close proximity, leading to bridging Ge-Cl-Ge and Ge-H-Ge bonding environments supported by Ge2C2 heterocyclic manifolds. Reduction of a dimeric [RGeCl]2 species (R = anionic NHO, [(MeCNDipp)2C═CH]-; Dipp = 2,6-iPr2C6H3) did not give the expected acyclic RGeGeR analogue of an alkyne, but rather ligand migration/disproportionation transpired to yield the known diorganogermylene R2Ge and Ge metal. This process was examined computationally, and the ability of the reported anionic NHO to undergo atom migration chemistry contrasts with what is typically found with bulky monoanionic ligands (such as terphenyl ligands).

An Adaptable N-Heterocyclic Carbene Macrocycle Hosting Copper in Three Oxidation States.

A neutral hybrid macrocycle with two trans-positioned N-heterocyclic carbenes (NHCs) and two pyridine donors hosts copper in three oxidation states (+I-+III) in a series of structurally characterized complexes (1-3). Redox interconversion of [LCu]+/2+/3+ is electrochemically (quasi)reversible and occurs at moderate potentials (E1/2 =-0.45 V and +0.82 V (vs. Fc/Fc+ )). A linear CNHC -Cu-CNHC arrangement and hemilability of the two pyridine donors allows the ligand to adapt to the different stereoelectronic and coordination requirements of CuI versus CuII /CuIII . Analytical methods such as NMR, UV/Vis, IR, electron paramagnetic resonance, and Cu Kß high-energy-resolution fluorescence detection X-ray absorption spectroscopies, as well as DFT calculations, give insight into the geometric and electronic structures of the complexes. The XAS signatures of 1-3 are textbook examples for CuI , CuII , and CuIII species. Facile 2-electron interconversion combined with the exposure of two basic pyridine N sites in the reduced CuI form suggest that [LCu]+/2+/3+ may operate in catalysis via coupled 2 e- /2 H+ transfer.

Immobilization of N-Heterocyclic Carbene Compounds: A Synthetic Perspective.

Over the course of the past 15 years the success story of N-heterocyclic carbene (NHC) compounds in organic, inorganic, and organometallic chemistry has been extended to another dimension. The immobilization of NHC compounds, undergoing continuous diversification, broadens their range of applications and leads to new solutions for challenges in catalytic and synthetic chemistry. This review intends to present a synthetic toolkit for the immobilization of NHC compounds, giving the reader an overview on synthetic techniques and strategies available in the literature. By individually summarizing and assessing the synthetic steps of the immobilization process, a comprehensive picture of the strategies and methodologies for the immobilization of NHC compounds is presented. Furthermore, the characterization of supported NHC compounds is discussed in detail in order to set up necessary criteria for an in-depth analysis of the immobilized derivatives. Finally, the catalytic applications of immobilized NHC compounds are briefly reviewed to illustrate the practical use of this technique for a broad variety of reaction types.

Highly selective AlCl3 initiated intramolecular α-alkylation of α,ß-unsaturated lactams and lactones.

An unprecedented example of AlCl3 initiated intramolecular α-alkylation of α,ß-unsaturated lactams and lactones is reported. A variety of substrates containing an intramolecular diene yield exclusively regioselective six-membered ring products. This reaction protocol generates a new stereo centre which may be of high interest for the functionalization of bioactive coumarin and quinolinone derivatives.

Synthesis and physicochemical characterization of room temperature ionic liquids and their application in sodium ion batteries.

Sodium ion batteries (SIBs) based on IL electrolytes have attracted great attention, particularly in large-scale energy storage systems for renewable energy due to the abundance of sodium and the excellent safety resulting from the use of non-flammable ionic liquid (IL) electrolytes. In this article, a series of 15 functionalized room temperature ionic liquids (RTILs) suitable as electrolytes is presented. Special emphasis was laid on the purity of the synthesized RTILs and a consistent and uniform characterization of their physicochemical properties. Evaluation of the viscosity, conductivity, and thermal and electrochemical stabilities resulted in clear structure-property relationships, rendering the ether functionalized RTILs most promising for application in SIBs. Electrochemical investigations of the ether functionalized IL electrolytes in SIB half cells (Na0.6Mn0.9Co0.1O2 as cathode material) proved their compatibility with a SIB system. Stable cycling performance was achieved with the piperidinium based RTIL IL 6 outperforming the organic electrolyte by far with a retention of 81% after 350 cycles. These results show the suitability of RTILs to enhance the performance of SIB systems and serve as a basis for the design of high performance IL electrolytes.

On the Mechanism of Gold/NHC Compounds Binding to DNA G-Quadruplexes: Combined Metadynamics and Biophysical Methods.

The binding modes and free-energy landscape of two AuI /N-heterocyclic carbene complexes interacting with G-quadruplexes, namely a human telomeric (hTelo) and a promoter sequence (C-KIT1), are studied here for the first time by metadynamics. The theoretical results are validated by FRET DNA melting assays and provide an accurate estimate of the absolute gold complex/DNA binding free energy. This advanced in silico approach is valuable to achieve rational drug design of selective G4 binders.

Characterization of Hydrophilic Gold(I) N-Heterocyclic Carbene (NHC) Complexes as Potent TrxR Inhibitors Using Biochemical and Mass Spectrometric Approaches.

We report here on the synthesis of a series of mono- and dinuclear gold(I) complexes exhibiting sulfonated bis(NHC) ligands and novel hydroxylated mono(NHC) Au(I) compounds, which were also examined for their biological activities. Initial cell viability assays show strong antiproliferative activities of the hydroxylated mono(NHC) gold compounds (8 > 9 > 10) against 2008 human ovarian cancer cells even after 1 h incubation. In order to gain insight into the mechanism of biological action of the gold compounds, their effect on the pivotal cellular target seleno-enzyme thioredoxin reductase (TrxR), involved in the maintenance of intracellular redox balance, was investigated in depth. The compounds' inhibitory effects on TrxR and glutathione reductase (GR) were studied comparatively, using either the pure proteins or cancer cell extracts. The results show a strong and selective inhibitory effect of TrxR, specifically for the hydroxyl-functionalized NHC gold(I) complexes (8-10). Valuable information on the gold compounds' molecular reactivity with TrxR was gained using the BIAM (biotin-conjugated iodoacetamide) assay and performing competition experiments by mass spectrometry (MS). In good agreement, both techniques suggest the binding affinity of the mono(NHC) Au(I) complexes toward selenols and thiols. Notably, for the first time, bis-carbene formation from mono-carbenes in buffered solution could be observed by MS, which may provide new insights into the speciation mechanisms of bioactive Au(I) NHC complexes. Furthermore, the compounds' interactions with another relevant in cellulo target, namely telomeric G-quadruplex DNA-a higher-order DNA structure playing key roles in telomere function-was investigated by means of FRET melting assays. The lack of interactions with this type of nucleic acid secondary structure support the idea of selective targeting of the hydrophilic Au(I) NHC compounds toward proteins such as TrxR.

Exploring the C

A family of cyclometalated Au(III) complexes featuring a tridentate C^N^C scaffold has been synthesized and characterized. Microwave assisted synthesis of the ligands has also been exploited and optimized. The biological properties of the thus formed compounds have been studied in cancer cells and demonstrate generally moderate antiproliferative effects. Initial mechanistic insights have also been gained on the gold complex [Au(C^N^C)(GluS)] (3), and support the idea that the thioredoxin system may be a target for this family of compounds together with other relevant intracellular thiol-containing molecules.

Evaluation of New Palladium Cages as Potential Delivery Systems for the Anticancer Drug Cisplatin.

Self-assembled metallocages are very promising drug-delivery systems among supramolecular complexes. Thus, exo-functionalized Pd2 L4 (L=ligand) cages were synthesized and characterized, and the encapsulation of the anticancer drug cisplatin in their cavity has been documented. The antiproliferative effects of the metallocages and their combination with cisplatin were examined in vitro in cancer cell lines, while fluorescence microscopy was used to monitor their uptake. Notably, the hydroxymethyl-functionalized Pd(II) cage encapsulating cisplatin showed improved cytotoxic effect against human ovarian cancer cells compared to free cisplatin. The toxicity of Pd2 L4 cages was evaluated for the first time ex vivo in healthy rat-liver tissues using the precision cut-tissue slices technology, demonstrating in some cases scarce effects on liver viability. These results further highlight the potential of self-assembled Pd2 L4 cages for biological applications.

Molecular Epoxidation Reactions Catalyzed by Rhenium, Molybdenum, and Iron Complexes.

Epoxidations are of high relevance in many organic syntheses, both in industry and academia. In this personal account, the development of rhenium, molybdenum, and iron complexes in molecular epoxidation catalysis is presented. Methyltrioxorhenium (MTO) is the benchmark catalyst for these reactions, with a thoroughly investigated mechanism and reactivity profile. More recently, highly active molecular molybdenum and iron catalysts have emerged, challenging the extraordinary role of MTO in epoxidation catalysis with high turnover frequencies (TOFs). This development is highlighted in its use of cheaper, more readily available metals, and the challenges of using base metals in catalysis are discussed. These results show the promise that relatively cheap and abundant metals, such as molybdenum and iron, hold for the future of epoxidation catalysis.