Intramolecular Triplet Diffusion Facilitates Triplet Dissociation in a Pentacene Hexamer

Triplet dynamics in singlet fission depend strongly on the strength of the electronic coupling. Covalent systems in solution offer precise control over such couplings. Nonetheless, efficient free triplet generation remains elusive in most systems, as the intermediate triplet pair 1(T1T1) is prone to triplet‐triplet annihilation due to its spatial confinement. In the solid state, entropically driven triplet diffusion assists in the spatial separation of triplets, resulting in higher yields of free triplets. Control over electronic coupling in the solid state is, however, challenging given its sensitivity to molecular packing. We have thus developed a hexameric system (HexPnc) to enable solid‐state‐like triplet diffusion at the molecular scale. This system is realized by covalently tethering three pentacene dimers to a central subphthalocyanine scaffold. Transient absorption spectroscopy, complemented by theoretical structural optimizations and steady‐state spectroscopy, reveals that triplet diffusion is indeed facilitated due to intramolecular cluster formation. The yield of free triplets in HexPnc is increased by a factor of up to 14 compared to the corresponding dimeric reference (DiPnc). Thus, HexPnc establishes crucial design aspects for achieving efficient triplet dissociation in strongly coupled systems by providing avenues for diffusive separation of 1(T1T1), while, concomitantly, retaining strong interchromophore coupling which preserves rapid formation of 1(T1T1).Efficient free triplet generation via singlet fission remains elusive in covalent systems. We have developed a hexameric pentacene system, in which three pentacene dimers are covalently linked to a central subphthalocyanine scaffold. This allows for an entropically driven triplet diffusion, resulting in higher yields of free triplets, and establishes crucial design aspects for achieving efficient triplet dissociation in strongly coupled systems. image Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/50110000165

DNA Methylation in Stroke. Update of Latest Advances

© 2017 The Authors. Epigenetic modifications are hereditable and modifiable factors that do not alter the DNA sequence. These epigenetic factors include DNA methylation, acetylation of histones and non-coding RNAs. Epigenetic factors have mainly been associated with cancer but also with other diseases and conditions such as diabetes or obesity. In addition, epigenetic modifications could play an important role in cardiovascular diseases, including stroke. We review the latest advances in stroke epigenetics, focusing on DNA methylation studies and the future perspectives in this field

Impact of pre-existing mental health diagnoses on development of post-COVID and related symptoms: a claims data-based cohort study

Abstract This study aimed to examine the association of prior mental health diagnoses with the onset of Post-COVID-19 condition (PCC). We conducted a retrospective comparative cohort study and secondary analysis of routinely collected claims data from participants in statutory health insurance in Bavaria, Germany, from January 2015 to June 2022. Study participants were 619,560 patients with confirmed COVID-19, 42,969 with other respiratory tract infection (ORI), and 438,023 controls. Using diagnoses coded according to the German modification of the ICD-10, the associations between prior mental health diagnoses and a PCC diagnosis (primary outcome) or associated symptoms (secondary outcomes) were estimated using multiple Cox proportional hazards regression models. Mental disorders (hazard ratio [HR] 1.36, 95% confidence interval [CI] 1.30–1.42), anxiety (HR 1.14, 95% CI 1.07–1.20), depression (HR 1.25, 95% CI 1.19–1.30) and somatoform disorders (HR 1.30, 95% CI 1.24–1.36) were associated with higher risks for PCC. Mental disorders were associated with the same or even greater risk for a diagnosis of malaise and fatigue in the control cohort (HR 1.71, 95% CI 1.52–1.93) and ORI cohort (HR 1.43, 95% CI 1.20–1.72), than in the COVID-19 cohort (HR 1.43, 95% CI 1.35–1.51). In summary, prior mental comorbidity was associated with an increased risk of PCC and its associated symptoms in all cohorts, not specifically in COVID-19 patients