Tetrathiafulvalene-oligofluorene star-shaped systems : new semiconductor materials for fluorescent moisture indicators

A series of novel star-shaped oligofluorene–thiophene–tetrathiafulvalene systems have been synthesised, following different synthetic routes. Each system incorporates a tetrathiafulvalene redox-active centre and four oligofluorene arms, providing a two-dimensional character to the conjugated backbone. The oligomers differ in the number of fluorene units present in the arms (1 to 4) and the terminal groups at the end of each arm (H or trimethylsilyl). Half-unit oligofluorene systems possessing a 1,3-dithiole-2-one core (a known precursor to the tetrathiafulvalene centre) have been synthesised in order to compare the thermal, optical and electrochemical properties. These half-unit systems consist of a 1,3-dithiole-2-one core fused to a thiophene unit at the 3- and 4-positions. Two oligofluorene arms consisting of 1 to 4 monomer units per arm are positioned at the 4- and 6-positions of the thiophene unit, affording extended conjugation through the thiophene centre. The half-unit systems are found to be moderate emitters in solution, however, the star-shaped systems bearing the tetrathiafulvalene core exhibit inhibited fluorescence in both solution and the solid state. We have demonstrated that the emission of the tetrathiafulvalene systems can be enhanced through the oxidation of the redox-centre followed by a consecutive reaction of the strongly electrophilic tetrathiafulvalene dication with such nucleophiles as water and hydrazine. The result of these reactions leads to an increase in the photoluminescence of these systems, affording the opportunity for the tetrathiafulvalene materials to be used as photonic materials in moisture indicators

Effect of angiotensin-converting enzyme inhibitor and angiotensin receptor blocker initiation on organ support-free days in patients hospitalized with COVID-19

IMPORTANCE Overactivation of the renin-angiotensin system (RAS) may contribute to poor clinical outcomes in patients with COVID-19. Objective To determine whether angiotensin-converting enzyme (ACE) inhibitor or angiotensin receptor blocker (ARB) initiation improves outcomes in patients hospitalized for COVID-19. DESIGN, SETTING, AND PARTICIPANTS In an ongoing, adaptive platform randomized clinical trial, 721 critically ill and 58 non–critically ill hospitalized adults were randomized to receive an RAS inhibitor or control between March 16, 2021, and February 25, 2022, at 69 sites in 7 countries (final follow-up on June 1, 2022). INTERVENTIONS Patients were randomized to receive open-label initiation of an ACE inhibitor (n = 257), ARB (n = 248), ARB in combination with DMX-200 (a chemokine receptor-2 inhibitor; n = 10), or no RAS inhibitor (control; n = 264) for up to 10 days. MAIN OUTCOMES AND MEASURES The primary outcome was organ support–free days, a composite of hospital survival and days alive without cardiovascular or respiratory organ support through 21 days. The primary analysis was a bayesian cumulative logistic model. Odds ratios (ORs) greater than 1 represent improved outcomes. RESULTS On February 25, 2022, enrollment was discontinued due to safety concerns. Among 679 critically ill patients with available primary outcome data, the median age was 56 years and 239 participants (35.2%) were women. Median (IQR) organ support–free days among critically ill patients was 10 (–1 to 16) in the ACE inhibitor group (n = 231), 8 (–1 to 17) in the ARB group (n = 217), and 12 (0 to 17) in the control group (n = 231) (median adjusted odds ratios of 0.77 [95% bayesian credible interval, 0.58-1.06] for improvement for ACE inhibitor and 0.76 [95% credible interval, 0.56-1.05] for ARB compared with control). The posterior probabilities that ACE inhibitors and ARBs worsened organ support–free days compared with control were 94.9% and 95.4%, respectively. Hospital survival occurred in 166 of 231 critically ill participants (71.9%) in the ACE inhibitor group, 152 of 217 (70.0%) in the ARB group, and 182 of 231 (78.8%) in the control group (posterior probabilities that ACE inhibitor and ARB worsened hospital survival compared with control were 95.3% and 98.1%, respectively). CONCLUSIONS AND RELEVANCE In this trial, among critically ill adults with COVID-19, initiation of an ACE inhibitor or ARB did not improve, and likely worsened, clinical outcomes. TRIAL REGISTRATION ClinicalTrials.gov Identifier: NCT0273570

Synthesis and characterisation of new tetrathiafulvalene-oligofluorene derivatives for moisture indicators

The term 'smart materials' refers to a category of materials that are able to dynamically respond to external stimuli through a change in physical and/or chemical properties. The versatility afforded by organic materials makes them attractive candidates in the development of new sensing materials. An in-depth understanding of the structure property relationships that drive a sensing material is a necessity in understanding device operation and reliably predicting their performance. Chapter 1 provides an overview of organic stimuli responsive materials and the types of physical properties that can induce a response in such materials. Chapter 1 further introduces the operating principles of sensors and their applications. Chapter 2 provides an introduction to the development of the novel hexylatedoligofluorene-thiophene systems wherein versatile 1,3-dithiole-2-one moiety is incorporated into the centre of the oligofluorene systems. The chapter follows a synthetic strategy used as a way to increase the dimensionality of oligofluorenesystems and discusses the influence of the synthetic strategy vis-à-vis yield and reproducibility of the systems. Chapter 2 further looks at the impact of the core uniton the photophysical behaviour of the oligofluorene spores and discusses the changes in the thermal and electronic properties of the new oligofluorene-thiophene systems as a consequence of the core unit. Chapter 3 discusses the development of new star-shaped oligofluorene-thiophene systems wherein redox-active dithiophene-tetrathiafulvalene is used as a core unit, providing an increase in dimensionality to a plurality of hexylated oligofluorenespores. The synthesis and properties of the oligofluorene systems are discussed. The photophysical behaviour, thermal and electronic properties of the new systems are investigated. Furthermore the core system displayed upon oxidation interesting features as fluorescence moisture indicator and are further investigated wherein the proof of concept is visible to the naked eye. The experimental procedures of chapters 2-3 are presented in chapter 4The term 'smart materials' refers to a category of materials that are able to dynamically respond to external stimuli through a change in physical and/or chemical properties. The versatility afforded by organic materials makes them attractive candidates in the development of new sensing materials. An in-depth understanding of the structure property relationships that drive a sensing material is a necessity in understanding device operation and reliably predicting their performance. Chapter 1 provides an overview of organic stimuli responsive materials and the types of physical properties that can induce a response in such materials. Chapter 1 further introduces the operating principles of sensors and their applications. Chapter 2 provides an introduction to the development of the novel hexylatedoligofluorene-thiophene systems wherein versatile 1,3-dithiole-2-one moiety is incorporated into the centre of the oligofluorene systems. The chapter follows a synthetic strategy used as a way to increase the dimensionality of oligofluorenesystems and discusses the influence of the synthetic strategy vis-à-vis yield and reproducibility of the systems. Chapter 2 further looks at the impact of the core uniton the photophysical behaviour of the oligofluorene spores and discusses the changes in the thermal and electronic properties of the new oligofluorene-thiophene systems as a consequence of the core unit. Chapter 3 discusses the development of new star-shaped oligofluorene-thiophene systems wherein redox-active dithiophene-tetrathiafulvalene is used as a core unit, providing an increase in dimensionality to a plurality of hexylated oligofluorenespores. The synthesis and properties of the oligofluorene systems are discussed. The photophysical behaviour, thermal and electronic properties of the new systems are investigated. Furthermore the core system displayed upon oxidation interesting features as fluorescence moisture indicator and are further investigated wherein the proof of concept is visible to the naked eye. The experimental procedures of chapters 2-3 are presented in chapter

Effect of Antiplatelet Therapy on Survival and Organ Support–Free Days in Critically Ill Patients With COVID-19

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