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The effect of high-flow oxygen therapy vs conventional oxygen therapy has not been established in the setting of severe COVID-19.To determine the effect of high-flow oxygen therapy through a nasal cannula compared with conventional oxygen therapy on need for endotracheal intubation and clinical recovery in severe COVID-19.Randomized, open-label clinical trial conducted in emergency and intensive care units in 3 hospitals in Colombia. A total of 220 adults with respiratory distress and a ratio of partial pressure of arterial oxygen to fraction of inspired oxygen of less than 200 due to COVID-19 were randomized from August 2020 to January 2021, with last follow-up on February 10, 2021.Patients were randomly assigned to receive high-flow oxygen through a nasal cannula (n = 109) or conventional oxygen therapy (n = 111).The co-primary outcomes were need for intubation and time to clinical recovery until day 28 as assessed by a 7-category ordinal scale (range, 1-7, with higher scores indicating a worse condition). Effects of treatments were calculated with a Cox proportional hazards model adjusted for hypoxemia severity, age, and comorbidities.Among 220 randomized patients, 199 were included in the analysis (median age, 60 years; n = 65 women [32.7%]). Intubation occurred in 34 (34.3%) randomized to high-flow oxygen therapy and in 51 (51.0%) randomized to conventional oxygen therapy (hazard ratio, 0.62; 95% CI, 0.39-0.96; P = .03). The median time to clinical recovery within 28 days was 11 (IQR, 9-14) days in patients randomized to high-flow oxygen therapy vs 14 (IQR, 11-19) days in those randomized to conventional oxygen therapy (hazard ratio, 1.39; 95% CI, 1.00-1.92; P = .047). Suspected bacterial pneumonia occurred in 13 patients (13.1%) randomized to high-flow oxygen and in 17 (17.0%) of those randomized to conventional oxygen therapy, while bacteremia was detected in 7 (7.1%) vs 11 (11.0%), respectively.Among patients with severe COVID-19, use of high-flow oxygen through a nasal cannula significantly decreased need for mechanical ventilation support and time to clinical recovery compared with conventional low-flow oxygen therapy.ClinicalTrials.gov Identifier: NCT04609462.

The size, shape, and number of nucleoli in a cell's nucleus might help to distinguish a malignant from a benign tumor. Cellular biology and histopathology often require better visualization to understand nucleoli-related processes, thus organelle-specific fluorescent markers are needed. Here, we report the design, synthesis, and fully chemo-photophysical characterization of fluorescent boron Schiff bases (BOSCHIBAs), derived from α-amino acids (i.e., phenylalanine, tyrosine and tryptophan), with nucleoli- and cytoplasm-specific staining in cells. It is the first time that Boron Schiff bases derived from α-amino acids act as notorious dual (nucleoli and cytoplasm) cell-staining fluorescent probes. The boron derivatives not only showed good photostability and acceptable quantum yields (∼5%) in solution, but also exhibited low cytotoxicity (>90% cell viability at 0.1 and 1 μg mL−1), which make them good candidates to be used in medical diagnosis.

The synthesis, characterization, and crystal structure analysis of five new steroidal molecular rotors constructed from two different building blocks, viz., mestranol, ethynylestradiol, levonorgest...

Made available in DSpace on 2020-12-12T02:34:53Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-05-24 In this work, we report the green synthesis of four luminescent organotin compounds 1–4 derived from amino acid Schiff bases (1: Naph-Trp-SnPh2, 2: Naph-Tyr-SnBu2, 3: Naph-Tyr-SnPh2, 4: Naph-Phe-SnPh2), obtained by ultrasound-assisted synthesis in short time (~20 min) and good yields (>95%). The molecular structure proposed in solution (1H and 119Sn NMR) was confirmed by X-ray diffraction study for compound 1 where the tin atom resides in trigonal bipyramid geometry. Luminescent silk fibroin scaffolds (SF 1–4) were elaborated with organotin compounds by freeze-drying technique. Photophysical properties of organotin compounds and scaffolds were obtained in solid state, observing bathochromic behaviors in tyrosine derived compounds, suggesting that the tyrosine produce supramolecular interactions across the –OH group that change the fluorescent properties. Scaffolds 1–4 were characterized by FTIR, XDR, TG/DTG, and SEM analysis. In addition, cytotoxic analysis of SF 1 presents high cellular viability, which could be applied as a scaffold in tissue engineering. Universidad Autónoma de Nuevo León Facultad de Ciencias Químicas, Ciudad Universitaria, Av. Universidad s/n Departamento de Química Centro de Investigación y de Estudios Avanzados del IPN, A. P. 14-740 São Carlos Institute of Physics – University of São Paulo (USP) Laboratory of Polymers and Biomaterials University of Araraquara (UNIARA) Department of Chemistry and Chemical Engineering Chalmers University of Technology Institute of Chemistry São Paulo State University - Unesp, CP355, Zip Code 14801-970 Institute of Chemistry São Paulo State University - Unesp, CP355, Zip Code 14801-970

The synthesis and characterization of a new Carbonic dihydrazide, bis[2-(hydroxyimino)-1-methylpropylidene] is described. The compound was characterized by NMR (1H, 13C), high-resolution mass spectrometry and X-ray diffraction. We observed the ligand with anti-trans conformation in solid state and symmetric (C2) conformer in solution. The relative energies of the conformers were calculated, using the density functional theory (DFT) to determine their relative stability. Both the single-crystal and calculated structures indicate that the asymmetric conformer is the most stable conformer in the absence of solvent.

Four organotin compounds bearing Schiff bases were prepared via a multicomponent microwave-assisted reaction among 2-hydroxy-1-naphthaldehyde, 2-aminophenol derivatives and the corresponding diorganotin oxide (R2SnO, R = nBu or Ph), with high yields and a low economic/environmental impact. All of the compounds were fully characterized by NMR (1H, 13C, and 119Sn) spectroscopy, high-resolution mass spectrometry, X-ray diffraction, cyclic voltammetry, UV/Vis spectroscopy, and fluorescence spectroscopy. All of the compounds absorb in the visible region around 480–490 nm, close to the maximum solar emission, with an optical band gap of around 2.3 eV and low fluorescence quantum yields. According to the electrochemical study, they present LUMO values close to that of [6,6]-phenyl-C61-butyric acid methyl ester (PCBM-C60), a typical electron acceptor organic photovoltaic material. Based on this combined optical/electrochemical study and as it allows the preparation of homogeneous spun films, the n-butyltin complex with carboxylic acid was selected for the investigation of its possible photovoltaic properties in organic solar cells. Charge photogeneration was obtained only using this organotin compound as an electron acceptor material with poly(3-hexylthiophene, P3HT) (typical electron donor material) with an open circuit voltage of 300 mV, a short-circuit current density of 0.11 mA cm−2 and an efficiency of 5.2 × 10−3%. Despite the fact that the efficiency is much lower with respect to the reference device P3HT/PCBM-C60, this preliminary result suggests that, after chemical and device processing optimization, tin complexes with Schiff bases could be applied as electron acceptor materials in organic photovoltaic devices.

In this work we report the microwave-assisted synthesis of six new pentacoordinate and chiral organotin compounds 1-6 derived from amino acid based Schiff bases. The syntheses were carried out by multicomponent reactions (MCRs) from L-amino acids (tryptophan, tyrosine, and phenylalanine), 2-hydroxy-1-naphthaldehyde and the corresponding diorganotin oxide (R2SnO, R = nBu or Ph). These compounds were characterized by using NMR (1H, 13C, and 119Sn), HRMS, UV-Vis, and fluorescence spectroscopy. All compounds exhibited in solution fluorescence with quantum yields (Φ) in the range of 0.08 to 0.21. Cytotoxicity activity shows that the compounds 1-6 at 0.1 µg mL-1 are practically harmless to melanoma B16F10 cells. The fluorescent staining ability of organotin compounds toward the silk fibroin was carried out by immersion method and analysed by confocal microscopy which showed the efficient and uniform integration of the luminescent compounds. Also, DFT calculations of truncated organotin-fibroin complex interactions are reported.

The regioselective opening of the F ring of 22-oxo-23-spiroketals 7a-d using TiCl

Here we report a green one-pot microwave-assisted synthesis of four push–pull organotin complexes derived from Schiff bases in good yields, which provides advancement over conventional method as it is simple, cost-effective and reproducible. All compounds were characterized by UV–Vis, TOF-HRMS, TGA-DTA, cyclic voltammetry, theoretical studies and compound 1 by X-ray single-crystal diffraction. Third-order nonlinear susceptibility χ(3) of complexes 1–4; ((E)-N′-(4-(diethylamino)-2-hydroxysalicylidine) nitrobenzohydrazidatediphenyl-tin (IV) (1), (E)-N′-(4-(diethylamino)-2-hydroxysalicylidine) nitrobenzohydrazidate di n-butyl-tin (IV) (2), ((E)-N′-(4-(methoxy)-2-hydroxysalicylidine) nitrobenzohydrazidate diphenyl-tin (IV) (3), (E)-N′-(4-(methoxy)-2-hydroxysalicylidine) nitrobenzohydrazidate di n-butyl-tin (IV) (4)) were measured via Maker-Fringes technique. In particular, compounds 1 and 2 display larger third-order nonlinearities than their methoxilated counterparts.

Thirteen steroidal derivatives were synthesized through a Sonogashira cross-coupling reaction which has been found to be an excellent synthetic strategy to introduce halo-aromatic groups into C-17-ethynyl substituted steroidal frameworks. The structural modification was performed on ethynylestradiol, mestranol, norethisterone, ethisterone and 3-ethynyl-3-epi-sarsasapogenin. The solid state study by X-ray diffraction showed that most of them belong to the orthorhombic P212121 space group and the whole family has an “L” conformation, regardless of the nature of the steroid A-ring (3-hydroxy-aromatic or 3-oxo). Due to the presence of several moieties which are susceptible to forming secondary interactions, the crystalline packing is governed by O–H⋯O, C–H⋯O, and C–H⋯π interactions, and only 17α-(4′-iodophenylethynyl)-3-methoxy-estra-1,3,5(10)-trien-17-β-ol (mestranol derivative 3) showed an iodine–iodine interaction (dI⋯I = 4.116 A). The crystalline packing for ethynylestradiol derivatives 1, 2 and 4 showed the formation of holes with diameters greater than 5.2 A suggesting their potential application in host guest chemistry or as porous materials.

In this work, we describe the synthesis and solid-state characterization of a series of molecular rotors with tri-isopropylsilyloxy-substituted (TIPS) trityl stators axially linked to 1,4-diethynylphenylene, 3,6-diethynyl-1,2-difluorophenylene and 2,5-diethynylpyridine rotators to produce 1,4-bis[(3,3-diphenyl-3-(3′-(tri-isopropylsilyloxy)-phenyl)-prop-1-yn-1-yl)]benzene (1), 1,4-bis[(3,3-diphenyl-3-(3′-(tri-isopropylsilyloxy)-phenyl)-prop-1-yn-1-yl)]-2,3-difluorobenzene (2) and 2,5-bis[(3,3-diphenyl-3-(3′-tri-isopropylsilyloxy)-phenyl)-prop-1-yn-1-yl)]pyridine (3). The subsequent removal of the TIPS protecting group led to their corresponding hydroxyl-substituted trityl derivatives (4) and (5). TIPS- and HO-substituted stators are involved in different inter- and intramolecular interactions (hydrogen bonding, phenyl embraces, C–H–π interactions) that give rise to isomorphic packing motifs that constrained the rotational dynamics in the solid-state to the slow exchange regime.

The synthesis and crystal structure of three new molecular rotors derived from levonorgestrel and norethisterone are reported. The conformation, close contacts, and shape characteristics of these molecules exhibiting Z′ = 2 and the inclusion of solvent molecules were analyzed together with the crystal structures of parent molecules retrieved from the Cambridge Structural Database. For the set of estranes studied, we confirmed that whenever an alternative conformer cannot satisfy the crystallographic symmetry, a second molecule is incorporated in the asymmetric unit resulting in conformational isomorphism (Z′ > 1). The shape of these molecules could make them interesting as potential hosts.

The regioselective opening of the F ring of 22-oxo-23-spiroketals 7a-d using TiCl4 in acetic anhydride yielded the novel furostanols 11a-d along with cholestanic derivatives 8a-d with pyranone E ring. The structures of the new derivatives thus obtained were established using one- (DEPT) and two-dimensional 1H, 13C NMR experiments (COSY, HSQC, HMBC, NOESY). The 22α-hydroxyl orientation in compounds 11a-d was proposed by comparison of the 13C chemical shifts with those of other aglycone members of this family, and confirmed by combined NOESY and X-ray diffraction analysis of compound 11a.

The trans-dichloro-trans-bis(dimethylsulfoxide)-trans-dimethyl-tin(IV) resulted from the reaction of dimethyl-tin(IV) dichloride and sodium sulfate in dimethylsulfoxide (DMSO). The tin compound was characterized by IR, NMR, FE-SEM, EDS, and single crystal X-ray diffraction studies. Suitable DMSO single crystals were obtained after 7 months by slow evaporation at room temperature. The crystal structure has a polymeric arrangement with eight-membered rings as a result of intermolecular coordination S O → Sn. The tin atom has an octahedral distorted geometry where the DMSO molecule is coordinated, and also has an infinite arrangement in 2D. Cytotoxicity against A431 cancer cells and MOLT4 leukemic cells and the DNA interaction of the organotin compound were determined. The organotin sulfate derivative showed low biological activity because of the polymeric structure and the saturated tin coordination capability.

A series of substituted 2-hydroxysalicylidine benzohydrazides were converted into their phenyl-boron complexes in good yields upon reaction with phenylboronic acid. All new compounds were characterized by NMR, UV, IR, spectroscopy and mass spectrometry. The X-ray structures of two complexes demonstrate that the boron atoms adopt a tetrahedral geometry. The 11B NMR chemical shifts of the boron atom in the complexes are also consistent with the presence of tetracoordinate boron centres. The photophysical properties of the free benzohydrazide ligands and their boron complexes have been determined and display quantum yields below 1% with lifetimes in the range 10−10–10−11 s.

The synthesis and structural characterization of six 1,4-diazepanes prepared by condensation of 2,2′-(1,3-propanediyldiimino)diphenols with glyoxal or 2,3-butanedione to give bisbenzoxazolidines and subsequent reduction with BH3–DMS is reported. The new 1,4-diazepanes were obtained in yields between 75% and 83% and characterized by NMR, IR, and HRMS. In addition, the crystal structure analysis showed that the seven-membered ring in 1,4-diazepanes (12a, 12e, and 12d) and bisbenzoxazolidines (11a, 11c, 11f) adopt in all cases twisted chair conformation. Compounds 12a and 12e show disorder in the seven member ring, as a result of the conformational flexibility of the seven-membered ring.

Symmetrical and unsymmetrical N , N ′-piperazine derivatives of (−)-norephedrine and o -aminophenol were synthesized stereoselectively in yields >70% by reduction of the corresponding N , N ′-ethylenebisoxazolidine heterocycles. The stereochemistry at the ring fusion carbons was established by NMR spectroscopy and X-ray crystallography.

The standard massic energies of combustion of three substituted bicyclic compounds: (4R*, 4′R*, 5R*, 5′R*)-5,5′-diphenyl-3,3′,4,4′-tetramethyl-2,2′-bioxazolidine; (2R*, 3R*, 6R*, 7R*) - 2, 6 - diphenyl - 3, 4, 7, 8 - tetramethyl -cis- perhydro - [1, 4] - oxazino - [3,2-b]-[1,4]-oxazine; and (2R*,3S*,6R*,7S*)-2,6-diphenyl-3,4,7,8-tetramethyl-cis-perhydro-[1,4]-oxazino-[3,2-b]-[1,4]-oxazine (these compounds will be referred as C1, C2, and C3, respectively, and their formulae are given in figure 1) were determined by oxygen bomb combustion calorimetry. The enthalpies of sublimation were determined by the Knudsen effusion method using a quartz-crystal microbalance. Based on the experimental results, the standard molar enthalpies of formation of the solid and gaseous compounds were determined. A summary of experimental and derived results at the temperatureT= 298.15 K is shown below. From these results it is concluded that the destabilization energy of C3 in relation to C2, due to the extra steric repulsion of thecis-methyl and phenyl substituents in C3 is approximately 12 kJ·mol−1in the condensed phase and is increased to approximately 19 kJ·mol−1in the gaseous phase. It was also verified that formation of oxazino-oxazines over bioxazolidine is thermodynamically favoured, because the enthalpy of formation of the latter is less negative.

The search for voluminous stators that may accommodate large rotator units and speed rotational dynamics in the solid state led us to investigate a simple and efficient method for the synthesis of molecular rotors with tert-butyldiphenylsilyl-protected (TBDPS) triphenylmethyl stators. Additionally, solid state characterization of these systems with two-, four-, and six-TBDPS groups provided us with a description of their crystallinity and thermal stability. Among them, molecular rotor 7c with the largest and most symmetric stator resulting from six peripheral silyl groups showed the best tendency to crystallize, and the study of its isotopologue 7c-d(4) by solid state (2)H NMR revealed a 2-fold motion of the 1,4-diethynylphenylene-d(4) rotator in the kHz regime.

Despite the evidence, the use of selective decontamination of the digestive tract (SDD) remains controversial, largely because of concerns that it may promote the emergence of antibiotic-resistant strains. The purpose of this study was to evaluate the long-term incidence of carriage of antibiotic-resistant bacteria (ARB), its clinical impact on developing infections and to explore risk factors of acquiring resistance. This study was conducted in one 18-bed medical-surgical intensive care unit (ICU). All consecutive patients admitted to the ICU who were expected to require tracheal intubation for longer than 48 h were given a 4-day course of intravenous cefotaxime, and enteral polymyxin E, tobramycin, amphotericin B in an oropharyngeal paste and digestive solution. Oropharyngeal and rectal swabs were obtained on admission and once a week. Diagnostic samples were obtained on clinical indication. During 5 years 1,588 patients were included in the study. The incidence density of ARB was stable: 18.91 carriers per 1,000 patient-days. The incidence of resistant Enterobacteriaceae was stable; the resistance of Pseudomonas aeruginosa to tobramycin, amikacin and ciprofloxacin was strongly reduced; there was an increase of P. aeruginosa resistant to ceftazidime and imipenem, associated with the increase in imipenem consumption; the incidence of other nonfermenter bacilli and oxacillin-resistant Staphylococcus aureus was close to zero. Ninety-seven patients developed 101 infections caused by ARB: 23 pneumonias, 20 bloodstream infections and 58 urinary tract infections. Abdominal surgery was the only risk factor associated with ARB acquisition [risk ratio 1.56 (1.10–2.19)]. Long-term use of SDD is not associated with an increase in acquisition of resistant flora.

The crystal structure of the title compound, C31H45BrO5·CH2Cl2, prepared in six steps from diosgenin, confirmed that the configurations of the stereogenic centers, positions 20S and 25R, remain unchanged during the reaction. The six-membered A, B and C rings have chair conformations. The five-membered ring D has an envelope conformation (with the methyl-substituted C atom fused to ring C as the flap) and the six-membered dihydro­pyran ring E adopts a twist-boat conformation. In the crystal, mol­ecules are linked via C—H⋯O and C—H⋯Cl hydrogen bonds, the latter involving the dichloro­methane solvent mol­ecule, forming a three-dimensional supra­molecular network.