Effect of Cp-Ligand Methylation on Rhodium(III)-Catalyzed Annulations of Aromatic Carboxylic Acids with Alkynes: Synthesis of Isocoumarins and PAHs for Organic Light-Emitting Devices

An efficient protocol was developed for the synthesis of π-extended isocoumarins and polycyclic aromatic hydrocarbons based on the oxidative coupling of aromatic carboxylic acids with internal alkynes catalyzed by (cyclopentadienyl)rhodium complexes. The coupling chemoselectivity strongly depends on whether Cp or the methylated Cp* ligands are used. The pentamethyl derivative [Cp*RhCl2]2 predominantly gives isocoumarins, while the non-methylated complex [CpRhI2]n produces naphthalene derivatives. The polyaromatic carboxylic acids (such as 1-naphthoic acid, 1-pyrenecarboxylic acid, fluorene-1-carboxylic acid, and dibenzofuran-4-carboxylic acid) are suitable for this approach. A mixture of Cp*H/RhCl3 can be used as a catalyst instead of [Cp*RhCl2]2. The structures of 3,4-diphenylindeno[1,2-h]isochromen-1(11H)-one and 7,10-dimethyl-8,9-diphenylbenzo[pqr]tetraphene were determined by X-ray diffraction. In addition, the optical properties of the prepared compounds were studied. 7,8-Diphenyl-10H-phenaleno[1,9-gh]isochromen-10-one was employed as an emissive layer for OLED manufacturing. The OLED emits yellow-green light with a maximum intensity 1740 cd ⋅ m−2 at 15 V. © 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinhei

Evolution of vortex matter, phase diagram, and upper critical field in the FeSe<inf>1-x </inf>S<inf>x</inf>system

We present a comprehensive study of vortex matter in the FeSe1-x S x system with various doping degree. The influence of sulphur substitution on peak effect occurrence is studied. Additionally, we study a possible vortex liquid-vortex glass/lattice transition and find an evidence that the vortex liquid-vortex glass phase transition in FeSe1-x S x has a quasi two-dimensional nature. We investigate the upper critical field behaviour in FeSe1-x S x system, and found that the upper critical field is higher than that predicted by the Werthamer-Helfand-Hohenberg (WHH) model, whereas its temperature dependence could be fitted within a two-band framework. Finally, a detailed H-T phase diagram is presented