Structures and properties of solvated and unsolvated isopropyl functionalised calix[4]arenes

The tetra-iso-propyl ethers of calix[4]arene and p-t-butylcalix[4]arene have been isolated in the cone conformation, and structurally characterized as chloroform solvates. Thermogravimetric analysis demonstrated that the parent iso-propylcalix[4]arene solvate is significantly more stable than the p-t-butylcalix[4]arene analogue, retaining the solvent up to a temperature of of 125 °C. It was found that the calix[4]arene ether sublimes at atmospheric pressure, and solvent-free crystals appropriate for structure determination were produced at reduced pressure. The p-t-butylcalix[4]arene ether was also isolated without solvent in the lattice, but in this case the calixarene was crystallized from acetone, as sublimation did not produce crystals of sufficient quality

A calixarene-based ion-selective electrode for thallium(I) detection

Three new calixarene Tl+ ionophores have been utilized in Tl+ ion-selective electrodes (ISEs) yieldingNernstian response in the concentration range of 10"2–10"6M TlNO3 with a non-optimized filling solution in a conventional liquid contact ISE configuration. The complex formation constants (log bIL) for two of the calixarene derivatives with thallium(I) (i.e. 6.44 and 5.85) were measured using the sandwich membrane technique, with the other ionophore immeasurable due to eventual precipitation of the ionophore during these long-term experiments. Furthermore, the unbiased selectivity coefficients for these ionophores displayed excellent selectivity against Zn2+, Ca2+, Ba2+, Cu2+, Cd2+ and Al3+ with moderate selectivity against Pb2+, Li+, Na+, H+, K+, NH4+ and Cs+, noting that silver was the only significant interferent with these calixarene-based ionophores. When optimizing the filling solution in a liquid contact ISE, it was possible to achieve a lower limit of detection of approximately 8 nM according to the IUPAC definition. Last, the new ionophores were also evaluated in four solid-contact (SC) designs leading to Nernstian response, with the best response noted with a SC electrode utilizing a gold substrate, a poly (3-octylthiophene) (POT) ion-to-electron transducer and a poly(methyl methacrylate)–poly(decylmethacrylate) (PMMA–PDMA) co-polymer membrane. This electrode exhibited a slope of 58.4 mV decade"1 and a lower detection limit of 30.2 nM. Due to the presence of an undesirable water layer and/or leaching of redox mediator from the graphite redox buffered SC, a coated wire electrode on gold and graphite redox buffered SC yielded grossly inferior detection limits against the polypyrrole/PVCSC and POT/PMMA–PDMA SC ISEs that did not display signs of a water layer or leaching of SC ingredients into the membrane

The extraction of thallium (I) and silver (I) ions with 1,3-alternate calix[4]arene derivatives

Tetraallyloxy and tetrabenzyloxy derivatives of calix[4]arenes in cone and 1,3-alternate conformations were synthesised and their capacity to extract thallium(I) and silver(I) ions was investigated. 'Low'-temperature single crystal X-ray structure determinations were recorded for two derivatives in which the calixarene conformation was that of an alternating cone, the aromatic rings lying closely quasi-parallel to the 4-axis of the cone. The structure of a tetraallyloxy derivative in the cone conformation was also determined in which a molecule of acetonitrile was included within the calixarene cavity

Obesity, inflammatory and thrombotic markers, and major clinical outcomes in critically ill patients with COVID‐19 in the US

Objective This study aimed to determine whether obesity is independently associated with major adverse clinical outcomes and inflammatory and thrombotic markers in critically ill patients with COVID‐19. Methods The primary outcome was in‐hospital mortality in adults with COVID‐19 admitted to intensive care units across the US. Secondary outcomes were acute respiratory distress syndrome (ARDS), acute kidney injury requiring renal replacement therapy (AKI‐RRT), thrombotic events, and seven blood markers of inflammation and thrombosis. Unadjusted and multivariable‐adjusted models were used. Results Among the 4,908 study patients, mean (SD) age was 60.9 (14.7) years, 3,095 (62.8%) were male, and 2,552 (52.0%) had obesity. In multivariable models, BMI was not associated with mortality. Higher BMI beginning at 25 kg/m2 was associated with a greater risk of ARDS and AKI‐RRT but not thrombosis. There was no clinically significant association between BMI and inflammatory or thrombotic markers. Conclusions In critically ill patients with COVID‐19, higher BMI was not associated with death or thrombotic events but was associated with a greater risk of ARDS and AKI‐RRT. The lack of an association between BMI and circulating biomarkers calls into question the paradigm that obesity contributes to poor outcomes in critically ill patients with COVID‐19 by upregulating systemic inflammatory and prothrombotic pathways