Square-Planar Anionic Pt0 Complexes.

A T-shaped Pt0 complex with a diphosphine-borane (DPB) ligand was prepared. The Pt→B interaction enhances the electrophilicity of the metal and triggers the addition of Lewis bases to give the corresponding tetracoordinate complexes. For the first time, anionic Pt0 complexes are isolated and structurally authenticated. X-ray diffraction analyses show the anionic complexes [(DPB)PtX]- (X=CN, Cl, Br, I) to be square-planar. The d10 configuration and Pt0 oxidation state of the metal were unambiguously established by X-ray photoelectron spectroscopy and DFT calculations. The coordination of Lewis acids as Z-type ligands is a powerful mean to stabilize elusive electron-rich metal complexes and achieve uncommon geometry.

Photoswitchable assembly of long-lived azobenzenes in water using visible light.

HYPOTHESIS: Switchable assemblies relevant for bio-applications may be accessed from water-soluble tetra-ortho-substituted azobenzenes that reversibly self-assemble and form complexes with ß-cyclodextrin under visible light. EXPERIMENTS: Two azobenzenes bearing either four fluorines or two chlorines and two fluorines in the ortho positions were synthesised with short poly(ethylene oxide) tails for water solubility. Photophysical properties were determined by UV-vis and 1H NMR spectroscopies, complexation with ß-cyclodextrin was assessed by 1H NMR spectroscopy, and self-assembly in water was investigated by static and dynamic light scattering. FINDINGS: Both molecules underwent trans-cis isomerization at 530 nm and cis-trans isomerization at 415 nm, with the cis forms exhibiting thermal half-lives > 300 days at room temperature. Both molecules formed inclusion complexes with ß-cyclodextrin in water, with cis-4F-AZO-PEO binding 3-fold stronger than trans, and 2Cl2F-AZO-PEO binding significantly weaker. Self-assembly of pure 2Cl2F-AZO-PEO in water showed an open association process regardless of configuration, while 4F-AZO-PEO showed an open association process for cis (Nagg increasing from 30 to 1000) but a closed association process for trans (Nagg stable at âˆ¼ 170). Aqueous solutions of 2Cl2F-AZO-PEO showed cloud points close to 45 °C, while the 4F-AZO-PEO isomers presented well-separated cloud points allowing reversible and all-visible transition between clear and turbid states at room temperature.

Mechanism of Alkyne Hydroarylation Catalyzed by (P,C)-Cyclometalated Au(III) Complexes.

Over the last 5-10 years, gold(III) catalysis has developed rapidly. It often shows complementary if not unique features compared to gold(I) catalysis. While recent work has enabled major synthetic progress in terms of scope and efficiency, very little is yet known about the mechanism of Au(III)-catalyzed transformations and the relevant key intermediates have rarely been authenticated. Here, we report a detailed experimental/computational mechanistic study of the recently reported intermolecular hydroarylation of alkynes catalyzed by (P,C)-cyclometalated Au(III) complexes. The cationic (P,C)Au(OAcF)+ complex (OAcF = OCOCF3) was authenticated by mass spectrometry (MS) in the gas phase and multi-nuclear NMR spectroscopy in solution at low temperatures. According to density functional theory (DFT) calculations, the OAcF moiety is κ2-coordinated to gold in the ground state, but the corresponding κ1-forms featuring a vacant coordination site sit only slightly higher in energy. Side-on coordination of the alkyne to Au(III) then promotes nucleophilic addition of the arene. The energy profiles for the reaction between trimethoxybenzene (TMB) and diphenylacetylene (DPA) were computed by DFT. The activation barrier is significantly lower for the outer-sphere pathway than for the alternative inner-sphere mechanism involving C-H activation of the arene followed by migratory insertion. The π-complex of DPA was characterized by MS. An unprecedented σ-arene Au(III) complex with TMB was also authenticated both in the gas phase and in solution. The cationic complexes [(P,C)Au(OAcF)]+ and [(P,C)Au(OAcF)(σ-TMB)]+ stand as active species and off-cycle resting state during catalysis, respectively. This study provides a rational basis for the further development of Au(III) catalysis based on π-activation.

Triterpenoid saponins and others glycosides from the stem barks of Pancovia turbinata Radlk.

In our continuing search of saponins from the plant of Sapindaceae family, phytochemical investigation of the stem barks of Pancovia turbinata Radlk., led to the isolation and structural characterization of two new triterpenoid saponins, named turbinatosides A-B (1-2), one new farnesyl glycoside, named turbinoside A (3), one new coumarin glucoside, named panturboside A (4), together with a known saponin (5). The structures of the new compounds were established, using extensive analysis of NMR techniques, mainly 1D NMR (1H, 13C, and DEPT) and 2D NMR (COSY, NOESY, HSQC, HSQC-TOCSY and HMBC) experiments, HRESIMS and by comparison with the literature data, as 3-O-ß-d-xylopyranosyl-(1 â†’ 3)-α-l-arabinopyranosyl-(1 â†’ 4)-ß-d-glucopyranosyl-(1 â†’ 3)-α-l-rhamnopyranosyl-(1 â†’ 2)-α-l-arabinopyranosylhederagenin 28-O-ß-d-glucopyranosyl ester (1), 3-O-α-l-arabinopyranosyl-(1 â†’ 4)-ß-d-glucopyranosyl-(1 â†’ 3)-α-l-rhamnopyranosyl-(1 â†’ 2)-α-l-arabinopyranosylhederagenin 28-O-ß-d-xylopyranosyl-(1 â†’ 4)-ß-d-glucopyranosyl ester (2), 1-O-{ß-d-glucopyranosyl-(1 â†’ 3)-α-l-rhamnopyranosyl-(1 â†’ 2)-[α-l-rhamnopyranosyl-(1 â†’ 6)]-ß-d-glucopyranosyl}-(2E,6E)-farnes-1,12-diol (3), and 5-O-ß-d-glucopyranosyl-5,6,7-trihydroxy-8-methoxycoumarin (4), respectively. Our findings highlight the presence of -3Rha-2Ara-3hederagenin oligosaccharidic sequence usually described in saponins from Sapindoideae subfamily of Sapindaceae family, as well as farnesol glycosides, and represent therefore a valuable contribution to the chemotaxonomy of the Sapindoideae subfamily.

Nucleophilic Addition to π-Allyl Gold(III) Complexes: Evidence for Direct and Undirect Paths.

π-Allyl complexes play a prominent role in organometallic chemistry and have attracted considerable attention, in particular the π-allyl Pd(II) complexes which are key intermediates in the Tsuji-Trost allylic substitution reaction. Despite the huge interest in π-complexes of gold, π-allyl Au(III) complexes were only authenticated very recently. Herein, we report the reactivity of (P,C)-cyclometalated Au(III) π-allyl complexes toward ß-diketo enolates. Behind an apparently trivial outcome, i.e. the formation of the corresponding allylation products, meticulous NMR studies combined with DFT calculations revealed a complex and rich mechanistic picture. Nucleophilic attack can occur at the central and terminal positions of the π-allyl as well as the metal itself. All paths are observed and are actually competitive, whereas addition to the terminal positions largely prevails for Pd(II). Auracyclobutanes and π-alkene Au(I) complexes were authenticated spectroscopically and crystallographically, and Au(III) σ-allyl complexes were unambiguously characterized by multinuclear NMR spectroscopy. Nucleophilic additions to the central position of the π-allyl and to gold are reversible. Over time, the auracyclobutanes and the Au(III) σ-allyl complexes evolve into the π-alkene Au(I) complexes and release the C-allylation products. The relevance of auracyclobutanes in gold-mediated cyclopropanation was demonstrated by inducing C-C coupling with iodine. The molecular orbitals of the π-allyl Au(III) complexes were analyzed in-depth, and the reaction profiles for the addition of ß-diketo enolates were thoroughly studied by DFT. Special attention was devoted to the regioselectivity of the nucleophilic attack, but C-C coupling to give the allylation products was also considered to give a complete picture of the reaction progress.

Use of Extracorporeal Membrane Oxygenation in Pneumocystis Pneumonia of an Infant with AIDS.

Pneumocystis pneumonia is a common complication of cellular immunosuppression and may trigger severe pulmonary complications. Rapid onset of acquired immunodeficiency syndrome is possible in infants infected with human immunodeficiency virus (HIV). We report here the case of a 13-week-old girl who was previously healthy presenting with altered immunity and refractory acute respiratory distress syndrome (ARDS) initially attributed to bacterial pneumonia. Venovenous extracorporeal membrane oxygenation (VV-ECMO) was initiated because her condition was poor. An HIV infection was later fortuitously diagnosed after accidental exposure of a nurse to the child's urine. The mother had congenitally transmitted HIV to the child after late (undetected) infection during pregnancy. The lung lesions were finally attributed to Pneumocystis pneumonia. We prescribed combined antiretroviral, antibiotic, and steroid therapy aimed at preventing immune reconstitution inflammatory syndrome. VV-ECMO weaning progressed over 30 days to the time of decannulation, rapidly followed by extubation and hospital discharge. The case highlights the fact that rare curable causes of refractory pediatric ARDS should always be investigated early. VV-ECMO should not be excluded as an ARDS treatment for immunocompromised children.

Farnesyl glycosides and one new triterpenoid saponin from the roots of Lecaniodiscus cupanioides Planch. ex Benth.

Chemical investigation of the methanol extract of the roots of Lecaniodiscus cupanioides led to the isolation and characterisation of three new sesquiterpene glycosides, named cupanioidesosides A (1), B (2) and C (3), together with one new triterpenoid saponin named lecanioside A (4), Their structures were established by extensive analysis of spectroscopic methods including 1D and 2D NMR techniques (COSY, NOESY, TOCSY, HSQC, and HMBC) and HRESIMS. The four new compounds were evaluated for their antiproliferative activity against the Caco-2 cell line (human epithelial cell line). None of the isolated compounds showed positive activity in our assay. Our findings represent a valuable contribution to the chemotaxonomy Lecaniodiscus genus of the subfamily of Sapindoideae of Sapindaceae family, known to be a rich source of farnesol glycosides.

Triterpenoid saponins from Calliandra calothyrsus Meisn. and their antiproliferative activity against two digestive carcinoma human cell lines.

The chemical investigation of the flowers and twigs of Calliandra calothyrsus (Fabaceae) led to the isolation of three new oleanane-type triterpenoid saponins, named calothyrsusosides AC (13). Their structures were established by direct interpretation of their spectral data, mainly HRESIMS, 1D NMR and 2D NMR (1H, 1H NMR DOSY, 13C NMR, COSY, HSQC, HMBC, HSQC-TOCSY and NOESY) and by comparison with literature data. Compounds 1 and 2 were tested for their antiproliferative activity against two digestive carcinoma human cell lines: Hep3B (hepatocellular carcinoma) and Caco-2 (epithelial colorectal adenocarcinoma). Both compounds exhibited an antiproliferative activity against the Hep3B cell line, with IC50 values of 6.0 and 6.5 µM, respectively, while no effect was detected against the epithelial colorectal adenocarcinoma Caco-2 (CC50 > 25 µM).

Association of a Frailty Screening Initiative With Postoperative Survival at 30, 180, and 365 Days.

Importance: As the US population ages, the number of operations performed on elderly patients will likely increase. Frailty predicts postoperative mortality and morbidity more than age alone, thus presenting opportunities to identify the highest-risk surgical patients and improve their outcomes. Objective: To examine the effect of the Frailty Screening Initiative (FSI) on mortality and complications by comparing the surgical outcomes of a cohort of surgical patients treated before and after implementation of the FSI. Design, Setting, and Participants: This single-site, facility-wide, prospective cohort quality improvement project studied all 9153 patients from a level 1b Veterans Affairs medical center who presented for major, elective, noncardiac surgery from October 1, 2007, to July 1, 2014. Interventions: Assessment of preoperative frailty in all patients scheduled for elective surgery began in July 2011. Frailty was assessed with the Risk Analysis Index (RAI), and the records of all frail patients (RAI score, ≥21) were flagged for administrative review by the chief of surgery (or designee) before the scheduled operation. On the basis of this review, clinicians from surgery, anesthesia, critical care, and palliative care were notified of the patient's frailty and associated surgical risks; if indicated, perioperative plans were modified based on team input. Main Outcomes and Measures: Postoperative mortality at 30, 180, and 365 days. Results: From October 1, 2007, to July 1, 2014, a total of 9153 patients underwent surgery (mean [SD] age, 60.3 [13.5] years; female, 653 [7.1%]; and white, 7096 [79.8%]). Overall 30-day mortality decreased from 1.6% (84 of 5275 patients) to 0.7% (26 of 3878 patients, P < .001) after FSI implementation. Improvement was greatest among frail patients (12.2% [24 of 197 patients] to 3.8% [16 of 424 patients], P < .001), although mortality rates also decreased among the robust patients (1.2% [60 of 5078 patients] to 0.3% [10 of 3454 patients], P < .001). The magnitude of improvement among frail patients increased at 180 (23.9% [47 of 197 patients] to 7.7% [30 of 389 patients], P < .001) and 365 days (34.5% [68 of 197 patients] to 11.7% [36 of 309 patients], P < .001). Multivariable models revealed improved survival after FSI implementation, controlling for age, frailty, and predicted mortality (adjusted odds ratio for 180-day survival, 2.87; 95% CI, 1.98-4.16). Conclusions and Relevance: Implementation of the FSI was associated with reduced mortality, suggesting the feasibility of widespread screening of patients preoperatively to identify frailty and the efficacy of system-level initiatives aimed at improving their surgical outcomes. Additional investigation is required to establish a causal connection.

Surgical palliative care consultations over time in relationship to systemwide frailty screening.

IMPORTANCE: The need for integrating palliative care into surgical services has been established within the surgical literature. The ability to effectively screen, obtain an appropriately timed consultation, and determine the effect of consultation remains problematic. OBJECTIVE: To examine surgical palliative care consultations over time and their relationship to the initiation and implementation of a systemwide frailty-screening program. DESIGN, SETTING, AND PARTICIPANTS: We reviewed all surgical palliative care consultations performed between January 1, 2006, and August 31, 2013, and abstracted the referring service (medicine/surgery), date of surgery (if any), date of death (if any), and all variables required to calculate a frailty score using the risk analysis index. We examined changes in mortality and referral patterns before and after implementation of the frailty-screening program using multivariable logistic regression. EXPOSURES: Surgical palliative care consultations, including frailty screening. MAIN OUTCOMES AND MEASURES: The primary study outcomes were 30-, 180-, and 360-day mortality. RESULTS: From 2006 to 2013, a total of 310 palliative care consultations were ordered for surgical patients: 160 before initiation of frailty screening (January 1, 2011) and 150 after initiation of the program. The groups had similar demographics, comorbidities, and frailty scores. After initiation, we observed dramatically decreased mortality at 30, 180, and 360 days (21.3% vs 31.9%, 44.0% vs 70.6%, and 66.0% vs 78.8%, respectively; all P < .05). This coincided with an increased rate of palliative care consultations from 32 per year to 56 per year. After initiation of the program, consultations were more likely to be requested by surgeons (56.7% vs 24.4%; P < .05) and were more likely to occur before the index operation (52.0% vs 26.3%; P < .05). Implementation of the screening program was associated with a 33% reduction in 180-day mortality (odds ratio [OR], 0.37; 95% CI, 0.22-0.62; P < .001) even after controlling for age, frailty, and whether the patients had surgery. Modeled mortality was also reduced when the palliative care consultation was ordered by a surgeon (OR, 0.50; CI, 0.30-0.83; P = .007) or ordered before the operation (OR, 0.52; CI, 0.30-0.90; P = .02). CONCLUSIONS AND RELEVANCE: Our data suggest that a systematic frailty-screening program effectively identifies at-risk surgical patients and is associated with a significant reduction in mortality for patients undergoing palliative care consultation. Analysis also suggests that preoperative palliative care consultations ordered by surgeons are associated with reduced mortality rates.

Mesomorphic ionic hyperbranched polymers: effect of structural parameters on liquid-crystalline properties and on the formation of gold nanohybrids.

Branched thermotropic liquid crystals were successfully obtained from ionic interactions between hyperbranched polyamidoamine and sodium dodecylsulfate. These complexes present columnar rectangular and lamellar thermotropic mesophases as demonstrated by polarized optical microscopy, differential scanning calorimetry, and small-angle X-ray scattering. The relationships between the structural characteristics of the polymers (size of the hyperbranched core, hyperbranched or dendritic nature of the core, and substitution ratio) and the mesomorphic properties were studied. In situ formation of gold nanoparticles was then performed. The templating effect of the liquid crystal mesophase resulted in the formation of isotropic nanoparticles, the size of which was dictated by the local organization of the mesophase and by the molar mass of the hyperbranched complex.

Ionic liquid/oil microemulsions as chemical nanoreactors.

The phase diagram and microstructure of the ternary system ionic, liquid benzylpyridinium bis(trifluoromethanesulfonyl)imide)/nonionic surfactant (octylphenol ethoxylate)/toluene, were studied by using conductivity measurements, dynamic light scattering, pulse field gradient spin-echo NMR, and small-angle neutron scattering. Three microregions were identified by conductivity measurements according to the percolation theory. The sizes of IL-in-oil microemulsions with various IL fractions were then determined by NMR and DLS and were found to be in accordance with the radii of gyration (approximately 2 or 3 nm) determined by SANS. The reverse IL-in-oil microemulsions were used as nanoreactors to perform a Matsuda-Heck reaction between p-methoxyphenyl diazonium salt and 2,3-dihydrofurane in the presence of a palladium catalyst. The reaction yields obtained were greater in microemulsions (67%) than in bulk IL (33%), highlighting a strong effect of confinement. Moreover, a direct correlation between the quantity of IL and the reaction yield was observed.