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- boronate (2)
- singlet oxygen (2)
- AIE (1)
- CardioMEMS™ HF-System (1)
- DNA/RNA binding (1)
- DNA/RNA sensors (1)
- alkyl halides (1)
- anaemia (1)
- aneurysmal subarachnoid haemorrhage (1)
- anticancer activity (1)
Ten thiosemicarbazone ligands obtained by condensation of pyridine-2-carbaldehyde, quinoline-2-carbaldehyde, 2-acetylpyridine, 2-acetylquinoline, or corresponding 2-pyridyl ketones with thiosemicarbazides RNHC(S)NHNH\(_{2}\) and R=CH\(_{3}\), C\(_{6}\)H\(_{5}\) were prepared in good yield. The reaction of [PdCl\(_{2}\)(cod)] with cod=1,5-cyclooctadiene or K\(_{2}\)[PtCl\(_{4}\)] resulted in a total of 17 Pd(II) and Pt(II) complexes isolated in excellent purity, as demonstrated by \(^{1}\)H, \(^{13}\)C, and, where applicable, \(^{195\)Pt NMR spectroscopy combined with CHNS analysis. The cytotoxicity of the title compounds was studied on four human glioblastoma cell lines (GaMG, U87, U138, and U343). The most active compound, with a Pd(II) metal centre, a 2-quinolinyl ring, and methyl groups on both the proximal C and distal N atoms exhibited an EC\(_{50}\) value of 2.1 μM on the GaMG cell lines, thus being slightly more active than cisplatin (EC\(_{50}\) 3.4 μM) and significantly more potent than temozolomide (EC\(_{50}\) 67.1 μM). Surprisingly, the EC\(_{50}\) values were inversely correlated with the lipophilicity, as determined with the “shake-flask method”, and decreased with the length of the alkyl substituents (C\(_{1}\)>C\(_{8}\)>C\(_{10}\)). Correlation with the different structural motifs showed that for the most promising anticancer activity, a maximum of two aromatic rings (either quinolinyl or pyridyl plus phenyl) combined with one methyl group are favoured and the Pd(II) complexes are slightly more potent than their Pt(II) analogues.
Designing highly efficient purely organic phosphors at room temperature remains a challenge because of fast non-radiative processes and slow intersystem crossing (ISC) rates. The majority of them emit only single component phosphorescence. Herein, we have prepared 3 isomers (o, m, p-bromophenyl)-bis(2,6-dimethylphenyl)boranes. Among the 3 isomers (o-, m- and p-BrTAB) synthesized, the ortho-one is the only one which shows dual phosphorescence, with a short lifetime of 0.8 ms and a long lifetime of 234 ms in the crystalline state at room temperature. Based on theoretical calculations and crystal structure analysis of o-BrTAB, the short lifetime component is ascribed to the T\(^M_1\) state of the monomer which emits the higher energy phosphorescence. The long-lived, lower energy phosphorescence emission is attributed to the T\(^A_1\) state of an aggregate, with multiple intermolecular interactions existing in crystalline o-BrTAB inhibiting nonradiative decay and stabilizing the triplet states efficiently.
Boric acid (BA) has been used as a transparent glass matrix for optical materials for over 100 years. However, recently, apparent room-temperature phosphorescence (RTP) from BA (crystalline and powder states) was reported (Zheng et al., Angew. Chem. Int. Ed. 2021, 60, 9500) when irradiated at 280 nm under ambient conditions. We suspected that RTP from their BA sample was induced by an unidentified impurity. Our experimental results show that pure BA synthesized from B(OMe)\(_{3}\) does not luminesce in the solid state when irradiated at 250–400 nm, while commercial BA indeed (faintly) luminesces. Our theoretical calculations show that neither individual BA molecules nor aggregates would absorb light at >175 nm, and we observe no absorption of solid pure BA experimentally at >200 nm. Therefore, it is not possible for pure BA to be excited at >250 nm even in the solid state. Thus, pure BA does not display RTP, whereas trace impurities can induce RTP.
A series of bis‐(4’‐pyridylethynyl)arenes (arene=benzene, tetrafluorobenzene, and anthracene) were synthesized and their bis‐N‐methylpyridinium compounds were investigated as a class of π‐extended methyl viologens. Their structures were determined by single crystal X‐ray diffraction, and their photophysical and electrochemical properties (cyclic voltammetry), as well as their interactions with DNA/RNA were investigated. The dications showed bathochromic shifts in emission compared to the neutral compounds. The neutral compounds showed very small Stokes shifts, which are a little larger for the dications. All of the compounds showed very short fluorescence lifetimes (<4 ns). The neutral compound with an anthracene core has a quantum yield of almost unity. With stronger acceptors, the analogous bis‐N‐methylpyridinium compound showed a larger two‐photon absorption cross‐section than its neutral precursor. All of the dicationic compounds interact with DNA/RNA; while the compounds with benzene and tetrafluorobenzene cores bind in the grooves, the one with an anthracene core intercalates as a consequence of its large, condensed aromatic linker moiety, and it aggregates within the polynucleotide when in excess over DNA/RNA. Moreover, all cationic compounds showed highly specific CD spectra upon binding to ds‐DNA/RNA, attributed to the rare case of forcing the planar, achiral molecule into a chiral rotamer, and negligible toxicity toward human cell lines at ≤10 μM concentrations. The anthracene‐analogue exhibited intracellular accumulation within lysosomes, preventing its interaction with cellular DNA/RNA. However, cytotoxicity was evident at 1 μM concentration upon exposure to light, due to singlet oxygen generation within cells. These multi‐faceted features, in combination with its two‐photon absorption properties, suggest it to be a promising lead compound for development of novel light‐activated theranostic agents.
Defunctionalization of readily available feedstocks to provide alkenes for the synthesis of multifunctional molecules represents an extremely useful process in organic synthesis. Herein, we describe a transition metal-free, simple and efficient strategy to access alkyl 1,2-bis(boronate esters) via regio- and diastereoselective diboration of secondary and tertiary alkyl halides (Br, Cl, I), tosylates, and alcohols. Control experiments demonstrated that the key to this high reactivity and selectivity is the addition of a combination of potassium iodide and N,N-dimethylacetamide (DMA). The practicality and industrial potential of this transformation are demonstrated by its operational simplicity, wide functional group tolerance, and the late-stage modification of complex molecules. From a drug discovery perspective, this synthetic method offers control of the position of diversification and diastereoselectivity in complex ring scaffolds, which would be especially useful in a lead optimization program.
Herein, the copper-catalyzed borylation of readily available acyl chlorides with bis(pinacolato)diboron, (B\(_{2}\)pin\(_{2}\)) or bis(neopentane glycolato)diboron (B\(_{2}\)neop\(_{2}\)) is reported, which provides stable potassium acyltrifluoroborates (KATs) in good yields from the acylboronate esters. A variety of functional groups are tolerated under the mild reaction conditions (room temperature) and substrates containing different carbon-skeletons, such as aryl, heteroaryl and primary, secondary, tertiary alkyl are applicable. Acyl N-methyliminodiacetic acid (MIDA) boronates can also been accessed by modification of the workup procedures. This process is scalable and also amenable to the late-stage conversion of carboxylic acid-containing drugs into their acylboron analogues, which have been challenging to prepare previously. A catalytic mechanism is proposed based on in situ monitoring of the reaction between p-toluoyl chloride and an NHC-copper(I) boryl complex as well as the isolation of an unusual lithium acylBpinOBpin compound as a key intermediate.
Three novel tetracationic bis‐triarylboranes with 3,4‐ethylenedioxythiophene (EDOT) linkers, and their neutral precursors, showed significant red‐shifted absorption and emission compared to their thiophene‐containing analogues, with one of the EDOT‐derivatives emitting in the NIR region. Only the EDOT‐linked trixylylborane tetracation was stable in aqueous solution, indicating that direct attachment of a thiophene or even 3‐methylthiophene to the boron atom is insufficient to provide hydrolytic stability in aqueous solution. Further comparative analysis of the EDOT‐linked trixylylborane tetracation and its bis‐thiophene analogue revealed efficient photo‐induced singlet oxygen production, with the consequent biological implications. Thus, both analogues bind strongly to ds‐DNA and BSA, very efficiently enter living human cells, accumulate in several different cytoplasmic organelles with no toxic effect but, under intense visible light irradiation, they exhibit almost instantaneous and very strong cytotoxic effects, presumably attributed to singlet oxygen production. Thus, both compounds are intriguing theranostic agents, whose intracellular and probably intra‐tissue location can be monitored by strong fluorescence, allowing switching on of the strong bioactivity by well‐focused visible light.
A practical and direct method was developed for the production of versatile alkyl boronate esters via transition metal-free borylation of primary and secondary alkyl sulfones. The key to the success of the strategy is the use of bis(neopentyl glycolato) diboron (B\(_{2}\)neop\(_{2}\)), with a stoichiometric amount of base as a promoter. The practicality and industrial potential of this protocol are highlighted by its wide functional group tolerance, the late-stage modification of complex compounds, no need for further transesterification, and operational simplicity. Radical clock, radical trap experiments, and EPR studies were conducted which show that the borylation process involves radical intermediates.
Purpose
Anaemia is common in patients presenting with aneurysmal subarachnoid (aSAH) and intracerebral haemorrhage (ICH). In surgical patients, anaemia was identified as an idenpendent risk factor for postoperative mortality, prolonged hospital length of stay (LOS) and increased risk of red blood cell (RBC) transfusion. This multicentre cohort observation study describes the incidence and effects of preoperative anaemia in this critical patient collective for a 10-year period.
Methods
This multicentre observational study included adult in-hospital surgical patients diagnosed with aSAH or ICH of 21 German hospitals (discharged from 1 January 2010 to 30 September 2020). Descriptive, univariate and multivariate analyses were performed to investigate the incidence and association of preoperative anaemia with RBC transfusion, in-hospital mortality and postoperative complications in patients with aSAH and ICH.
Results
A total of n = 9081 patients were analysed (aSAH n = 5008; ICH n = 4073). Preoperative anaemia was present at 28.3% in aSAH and 40.9% in ICH. RBC transfusion rates were 29.9% in aSAH and 29.3% in ICH. Multivariate analysis revealed that preoperative anaemia is associated with a higher risk for RBC transfusion (OR = 3.25 in aSAH, OR = 4.16 in ICH, p < 0.001), for in-hospital mortality (OR = 1.48 in aSAH, OR = 1.53 in ICH, p < 0.001) and for several postoperative complications.
Conclusions
Preoperative anaemia is associated with increased RBC transfusion rates, in-hospital mortality and postoperative complications in patients with aSAH and ICH.
Background
Remote monitoring of patients with New York Heart Association (NYHA) functional class III heart failure (HF) using daily transmission of pulmonary artery (PA) pressure values has shown a reduction in HF-related hospitalizations and improved quality of life in patients.
Objectives
PASSPORT-HF is a prospective, randomized, open, multicenter trial evaluating the effects of a hemodynamic-guided, HF nurse-led care approach using the CardioMEMS™ HF-System on clinical end points.
Methods and results
The PASSPORT-HF trial has been commissioned by the German Federal Joint Committee (G-BA) to ascertain the efficacy of PA pressure-guided remote care in the German health-care system. PASSPORT-HF includes adult HF patients in NYHA functional class III, who experienced an HF-related hospitalization within the last 12 months. Patients with reduced ejection fraction must be on stable guideline-directed pharmacotherapy. Patients will be randomized centrally 1:1 to implantation of a CardioMEMS™ sensor or control. All patients will receive post-discharge support facilitated by trained HF nurses providing structured telephone-based care. The trial will enroll 554 patients at about 50 study sites. The primary end point is a composite of the number of unplanned HF-related rehospitalizations or all-cause death after 12 months of follow-up, and all events will be adjudicated centrally. Secondary end points include device/system-related complications, components of the primary end point, days alive and out of hospital, disease-specific and generic health-related quality of life including their sub-scales, and laboratory parameters of organ damage and disease progression.
Conclusions
PASSPORT-HF will define the efficacy of implementing hemodynamic monitoring as a novel disease management tool in routine outpatient care.
Trial registration
ClinicalTrials.gov; NCT04398654, 13-MAY-2020.