Direct ladderization of cyclooctatetraene-containing, processable conjugated ladder polymers from annulated bis-zirconacyclopentadienes.

Conjugated ladder polymers (CLPs) are difficult yet captivating synthetic targets due to their fully unsaturated fused backbones. Inherent challenges associated with their synthesis often lead to low yields, structural defects, and insoluble products. Here a new method to form CLPs is demonstrated, utilizing a high-yielding dimerization of annulated zirconacyclopentadienes to form cyclooctatetraene (COT) monomer units.

Physical activity and psychopathology: are long-term developmental trajectories of physical activity in children and adolescents associated with trajectories of general mental health problems and of attention-deficit hyperactivity (ADHD) symptoms?

A medium-to-high level of physical activity (PA) may have at least a short-term positive effect on psychopathology in children and adolescents. Hence, the objective of this study was to investigate the long-term effects of PA in non-adult age groups on their general mental health problems and/or ADHD symptoms, using trajectories of concurrent development over a period of 10 years. This study employed data from the German Health Interview and Examination Survey for Children and Adolescents (KiGGS) collected at three time points (baseline, Wave 1, Wave 2, over 10 years) from 17,640 children and adolescents.

Long-term changes in serum levels of lipoproteins in children and adolescents with attention-deficit/hyperactivity disorder (ADHD).

Attention-deficit/hyperactivity disorder (ADHD) is a neurodevelopmental disorder affecting approximately 5% of children worldwide. The causal mechanisms of ADHD remain unclear as the aetiology of this disorder seems to be multifactorial. One research field addresses the impact on lipid metabolism and particularly serum lipid fractions on the development of ADHD symptoms.

Is only-child status associated with a higher blood pressure in adolescence? An observational study.

Growing up with siblings may affect quality of life as well as hemodynamic parameters including blood pressure. Using weighted data from the nationwide and representative German KiGGs study, we assessed the relationship between only-child status, birth order, and arterial blood pressure in a cohort of 7311 adolescents aged between 11 and 17 years. Our data showed that only-children had the highest mean arterial blood pressure (87.

Expanded [23]-Helicene with Exceptional Chiroptical Properties via an Iterative Ring-Fusion Strategy.

Expanded helicenes are an emerging class of helical nanocarbons composed of alternating linear and angularly fused rings, which give rise to an internal cavity and a large diameter. The latter is expected to impart exceptional chiroptical properties, but low enantiomerization free energy barriers (Δ) have largely precluded experimental interrogation of this prediction. Here, we report the syntheses of expanded helicenes containing 15, 19, and 23 rings on the inner helical circuit, using two iterations of an Ir-catalyzed, site-selective [2 + 2 + 2] reaction.