Enhanced reversible solid-state photoswitching of a cationic dithienylethene assembled with a polyoxometalate unit

International audienceThe first photochromic supramolecular assembly of a dithienylethene (DTE) cation with a polyoxometalate (POM) is elaborated. The POM unit modifies the photoswitching of the DTE in the solid state, via both steric and electronic effects, resulting in an increase of its cycloreversion rate, and an almost complete re-opening process. The crystal structure after exposure to UV light reveals a remarkable photocyclization yield of almost 28%. The structural model was greatly improved by theoretical calculations, and the absorption properties were nicely modeled from electronic structure calculations

Three-dimensional distribution of S wave reflectors in the northern Kinki district, southwestern Japan

Distinct reflected waves (S × S) are observed in the northern Kinki district, southwestern Japan. We conducted a high-resolution reflection analysis by using data from 128 seismic stations with an average spacing of about 5 km. We used a stacking method to obtain three-dimensional distributions of relative reflection strengths of S waves and found a thin planar zone of high reflection strengths at depths of 25-30 km, which we call a S wave reflector. We also found that the zone of high reflection strengths is dipping to the north and that low-frequency earthquakes (LFEs) occurred near the edge of the zone at depths around the Moho discontinuity. It is inferred from these results that fluid is concentrated in this zone of high reflection strengths. It is likely that the zone of high reflection strengths is a path of fluid upwelling from the mantle, together with the hypocentral region of LFEs, that is located near the lower edge of the zone. The northern Kinki district is thought to be part of the Niigata-Kobe Tectonic Zone (NKTZ) high strain rates region. The high reflection strengths zone may be associated with high strain rates in the NKTZ