The mechanism of cycloaddition reaction between carbon dioxide and epoxide, catalyzed by HEMIMC (1-(2-hydroxyl-ethyl)-3-methylimidazolium chloride), was investigated using the DFT (density functional theory) method. In the presence of HEMIMC, the reaction mechanism changed from single-step to multipath. Seven reaction pathways are reported here, including two steps, epoxide ring-opening and ring-closure of cyclic carbonate, or three main steps, epoxide ring-opening, carbon dioxide insertion, and ring-closure of cyclic carbonate. The catalytic activity of HEMIMC was studied, and the catalytic mechanism was elucidated. The nucleophilic attack of anion and hydrogen bond are two of the most important factors to promote the cycloaddition reaction, especially the OH functional group in HEMIMC. Finally, the influence of different anions on the catalytic activity was investigated.

HighlightsNi/TiO2 improves the hydrothermal liquefaction of Nannochloropsis.A reaction temperature of 300 °C leads to the best liquefaction effect.The viscosity, TAN, and boiling point distribution of biocrude changed with Ni/TiO2.Adding Ni/TiO2 results in more acids and hydrocarbons in biocrude.The Ni/TiO2 catalyst performs a good reproduction ability.

Power conversion efficiency (PCE) is one of the important factors in influencing the overall performance of dye-sensitized solar cells (DSSCs), and precise prediction of PCE is a feasible strategy for preparing highly efficient DSSCs devices. In this work, we designed a series of phenothiazine-based organic dyes by introducing different π-spacers including the 4-isopropyl-4H-dithieno­[3,2-b:2′,3′-d]­pyrrole (DTP) and 2,7-dihydronaphtho­[1,2-d:5,6-d′]­diimidazole (NDI) to tune their photovoltaic properties. The present studies reveal that the PCE value of the DTP-based dye is estimated to be 8.55%, in excellent agreement with the experimentally available value (8.19%) observed in the reported analogue. In comparison to DTP, the strong electron-deficiency NDI group induces a remarkable red-shifting of maximum absorption band, broadening the optical absorption into the near-infrared region. As a consequence, the NDI-based dye achieves an impressive PCE value of 15.51%, which is expected to be a potential organic dye applied in DSSCs.

A theoretical investigation into eighteen recently synthesized Pt(ii) complexes [(R1(n)-C^N^C-R2(n))Pt(L)] with doubly deprotonated cyclometalated R1(n)-C^N^C-R2(n) ligands (n = 1-9, R1(n)-C^N^C-R2(n) = 2,6-diphenylpyridine derivatives) and L ligands (L = DMSO, 1-9; L = -C[triple bond, length as m-dash]N-Ar, 1a-9a), which are used as emitters in orange-red emitting diodes, is reported in this paper. Geometric and electronic structures, absorption and emission spectra, phosphorescence quantum yields, and electroluminescence (EL) efficiency were investigated by DFT and TDDFT methods. We focused on the influence of the primary ligand (R1(n)-C^N^C-R2(n)) and auxiliary ligand (L) on the optical and electronic properties of Pt(ii) complexes by introducing carbazole, fluorene, and thiophene group in the primary ligand and/or the replacement of DMSO by -C[triple bond, length as m-dash]N-Ar as an ancillary ligand. The incorporation of carbazole, fluorene, and thiophene into the primary ligand caused the red-shift of absorption and emission spectra. The metal-ligand bond length is contracted where -C[triple bond, length as m-dash]N-Ar was employed as the secondary ligand, which facilitate the metal to ligand charge transfer (MLCT). The larger involvement of MLCT character in emission process is beneficial for improving the quantum yields of 2a-9a. For EL efficiency, all the complexes have a good balance of reorganization energy as potential systems for fabricating effective OLEDs devices except for 1 and 1a. In addition, two new molecules were designed with comparable or better EL efficiency.

No abstract