Improving the Performance of Supported Ionic Liquid Phase Catalysts for the Ultra-Low-Temperature Water Gas Shift Reaction Using Organic Salt Additives

The water gas shift reaction (WGSR) is catalyzed by supported ionic liquid phase (SILP) systems containing homogeneous Ru complexes dissolved in ionic liquids (ILs). These systems work at very low temperatures, that is, between 120 and 160 °C, as compared to >200 °C in the conventional process. To improve the performance of this ultra-low-temperature catalysis, we investigated the influence of various additives on the catalytic activity of these SILP systems. In particular, the application of methylene blue (MB) as an additive doubled the activity. Infrared spectroscopy measurements combined with density functional theory (DFT) calculations excluded a coordinative interaction of MB with the Ru complex. In contrast, state-of-the-art theoretical calculations elucidated the catalytic effect of the additives by non-covalent interactions. In particular, the additives can significantly lower the barrier of the rate-determining step of the reaction mechanism via formation of hydrogen bonds. The theoretical predictions, thereby, showed excellent agreement with the increase of experimental activity upon variation of the hydrogen bonding moieties in the additives investigated.

Interacting mechanism of benzo(a)pyrene with free DNA in vitro

Polycyclic aromatic hydrocarbons are environmental pollutants with strong carcinogenicity, indirect teratogenicity, and mutagenicity. This study explored the interaction mechanism of benzo(a)pyrene with free DNA in vitro by using various analytical methods. UV-vis spectra showed that benzo(a)pyrene and DNA formed a new benzo(a)pyrene-DNA complex. The thermal melting temperature of DNA increased by 12.7 °C, showing that the intercalation of benzo(a)pyrene into DNA could promote the stability of the DNA double helix structure. The intercalation of benzo(a)pyrene with DNA in vitro was further confirmed by fluorescence microscopy with magnetic beads. Fluorescence spectra showed that the interaction between DNA and benzo(a)pyrene decreased the fluorescence intensity of benzo(a)pyrene, and the maximum quenching rate was 27.89%. The quenching mode of benzo(a)pyrene was static quenching. Thermodynamic data showed that the main driving forces were van der Waals forces and hydrogen bonds, and the reaction was spontaneous. The results of this study provided a novel insight for the establishment of polycyclic aromatic hydrocarbon capture and elimination through polycyclic aromatic hydrocarbon-DNA intercalation.

Interaction between tryptophan-Sm(III) complex and DNA with the use of a acridine orange dye fluorophor probe

The interaction of the Trp-Sm(III) complex with herring sperm DNA (hs-DNA) was investigated with the use of acridine orange (AO) dye as a spectral probe for UV-vis spectrophotometry and fluorescence spectroscopy. The results showed that the both the Trp-Sm(III) complex and the AO molecule could intercalate into the double helix of the DNA. The Sm(III)-(Trp)3 complex was stabilized by intercalation into the DNA with binding constants: K(Ө)25°C  = 7.14 × 10(5)  L·mol(-1) and K(Ө) 37°C  = 5.28 × 10(4)  L·mol(-1), and it could displace the AO dye from the AO-DNA complex in a competitive reaction. Computation of the thermodynamic functions demonstrates that Δr Hm (Ө) is the primary driving power of the interaction between the Sm(III)(Trp)3 complex and the DNA. The results from Scatchard and viscometry methods suggested that the interaction mode between the Sm(III)(Trp)3 complex and the hs-DNA is groove binding and weak intercalation binding.