Thiomolybdate Clusters: From Homogeneous Catalysis to Heterogenization and Active Sites

Thiomolybdates are molecular molybdenum-sulfide clusters formed from Mo centers and sulfur-based ligands. For decades, they have attracted the interest of synthetic chemists due to their unique structures and their relevance in biological systems, e.g., as reactive sites in enzymes. More recently, thiomolybdates are explored from the catalytic point of view and applied as homogeneous and molecular mimics of heterogeneous molybdenum sulfide catalysts. This review summarizes prominent examples of thiomolybdate-based electro- and photocatalysis and provides a comprehensive analysis of their reactivities under homogeneous and heterogenized conditions. Active sites of thiomolybdates relevant for the hydrogen evolution reaction are examined, aiming to shed light on the link between cluster structure and performance. The shift from solution-phase to surface-supported thiomolybdates is discussed with a focus on applications in electrocatalysis and photocatalysis. The outlook highlights current trends and emerging areas of thiomolybdate research, ending with a summary of challenges and key takeaway messages based on the state-of-the-art research.

A conserved isoleucine in the binding pocket of RIG-I controls immune tolerance to mitochondrial RNA

RIG-I is a cytosolic receptor of viral RNA essential for the immune response to numerous RNA viruses. Accordingly, RIG-I must sensitively detect viral RNA yet tolerate abundant self-RNA species. The basic binding cleft and an aromatic amino acid of the RIG-I C-terminal domain(CTD) mediate high-affinity recognition of 5'triphosphorylated and 5'base-paired RNA(dsRNA). Here, we found that, while 5'unmodified hydroxyl(OH)-dsRNA demonstrated residual activation potential, 5'-monophosphate(5'p)-termini, present on most cellular RNAs, prevented RIG-I activation. Determination of CTD/dsRNA co-crystal structures and mutant activation studies revealed that the evolutionarily conserved I875 within the CTD sterically inhibits 5'p-dsRNA binding. RIG-I(I875A) was activated by both synthetic 5'p-dsRNA and endogenous long dsRNA within the polyA-rich fraction of total cellular RNA. RIG-I(I875A) specifically interacted with long, polyA-bearing, mitochondrial(mt) RNA, and depletion of mtRNA from total RNA abolished its activation. Altogether, our study demonstrates that avoidance of 5'p-RNA recognition is crucial to prevent mtRNA-triggered RIG-I-mediated autoinflammation.

Synthesis of a π-Extended Double [9]Helicene

Double helicenes are appealing chiral frameworks. Their π-extension is desirable to achieve (chir)optical response in the visible and near-infrared (NIR) region, but access to higher double [n]helicenes (n≥8) has remained challenging. Herein, we report an unprecedented π-extended double [9]helicene (D9H), unambiguously revealing its structure by single-crystal X-ray diffraction. D9H shows remarkable NIR emission from 750 to 1100 nm with a high photoluminescence quantum yield of 18 %. In addition, optically pure D9H exhibits panchromatic circular dichroism with a notable dissymmetry factor (g_CD ) of 0.019 at 590 nm, which is among the highest in the visible region for reported helicenes.

Determinants of university students' COVID-19 vaccination intentions and behavior

Vaccination hesitancy has been a major challenge for health authorities and societies during the COVID-19 pandemic. The general determinants of vaccination intentions and behavior include sociodemographic and health-related, psychological, and communication-related factors, with varying relevance for different types of vaccinations, countries, and target groups. The predictors of university students' COVID-19 vaccination behavior have not been sufficiently studied. Using a German university as an example and based on an online survey of 1398 university students, we investigated factors related to (a) the likelihood of vaccination against COVID-19 and (b) vaccination intention among those who had not been vaccinated by summer of 2021. Psychological factors showed high relevance. Field of study, trust in, and use of certain media and information channels were found to be important determinants of students' vaccination decision. Our findings can help better understand university students' vaccination behavior to develop and implement tailored strategies and campaigns.