Acid catalyzed α-alkylation of β-aminothiophenes with aldehydes. synthesis of 2-alkyl 3-thiophenamines,bis(3-amino-2-thienyl)-methane derivatives and dithieno[3,2-b:2′,3′-e]pyridines

The acid catalyzed reaction of 3-thiophenamines with aldehydes in the presence of selenophenol as the reducing agent, gives 2-alkyl-3-miophenamines. Without reduction, bis(3-amino-2-thienyl)methane derivatives have been obtained and transformed into dithieno[3,2-b:2′,3′-e]pyridines by thermal and acidic treatment when the substrates are primary amines. These new tricyclic heterocycles can be synthesized in a one-pot procedure from 3-thiophenamine.     

Structural,optical and gas sensing properties of Cu2O/CuO mixed phase: effect of the number of coated layers and (Cr + S) co-Doping

Thin films of Cu₂O/CuO mixed phase have been deposited on pre-cleaned glass substrate by a spin-coating technique. The influence of Cr-doping, (Cr?+?S) co-doping and the number of coated layers on the structures and optical behaviors of the films were investigated by X-ray diffraction (XRD), Fourier transform infrared (FTIR), Raman, and UV-Visible spectroscopies. From XRD, FTIR and Raman results; the films are composed of polycrystalline monoclinic CuO and cubic Cu₂O phases with crystallite sizes ranged from 10.05 to 23.08?nm. Increasing the thickness improves the films’ crystallinity and decreases the defects level in the films. Cr and S incorporation encourages the growth of CuO phase at the expense of Cu₂O one and affects the preferred growth direction. The doping with Cr and S blue shifted the B_g mode and multi-phonon transitions. The direct and indirect optical band gaps decreased from 2.25?eV and 1.60?eV to 2.10?eV and 1.20?eV by growing the number of deposited layers from 2 to 8 layers. The film sensitivity towards CO₂ at different gas flow rate was studied and compared with those of similar systems. Also; response time, recovery time, detection limit, and limit of quantification are estimated.