Observation of inserted oxocarbonyl species in the tantalum cation-mediated activation of carbon dioxide dictated by two-state reactivity.

Reductive activation of carbon dioxide (CO) has drawn increasing attention as an effective and convenient method to unlock this stable molecule, especially transition metal-catalyzed reactions. Taking the [TaCO] ion-molecule complex formed in the laser ablation source as a representative, the reactivity of the tantalum metal cation towards CO molecules is explored using infrared photodissociation spectroscopy combined with quantum chemical calculations. The strong absorption in the carbonyl stretching region provides solid evidence for the insertion reactions into CO bonds by the tantalum cation.

Infrared photodissociation spectroscopy of mass-selected [TaO(CO)] ( = 2-5) complexes in the gas phase.

We report a joint experimental and theoretical study on the structures of gas-phase [TaO(CO)] ( = 2-5) ion-molecule complexes. Infrared photodissociation spectra of mass-selected [TaO(CO)] complexes were recorded in the frequency region from 2200 to 2450 cm and assigned through comparing with the simulated infrared spectra of energetically low-lying structures derived from quantum chemical calculations. With the increasing number of attached CO molecules, the larger clusters show significantly enhanced fragmentation efficiency and a strong band appears at around 2350 cm near the free CO antisymmetric stretching vibration band, indicating only a small perturbation of CO molecules on the secondary solvation sphere while higher frequency bands corresponding to the core structure remain largely unaffected.

Inhibition of 32Dp210 cells harboring T315I mutation by a novel derivative of emodin correlates with down-regulation of BCR-ABL and its downstream signaling pathways.

Purpose: The clinical outcome of chronic myeloid leukemia (CML) patients has been changed dramatically due to the development of imatinib (IM). However, the emergence of IM resistance, commonly associated with point mutations within the BCR-ABL kinase domain, remains a major clinical problem. Here, we investigated the effects of E35, a novel derivative of emodin, on the IM-resistant 32Dp210-T315I cells.