Chu-Ting Yang

The coordination of amidoxime ligands with uranyl in the gas phase: a mass spectrometry and DFT study

Sequestering uranium from the ocean is a promising solution to fulfill the demand for nuclear energy. Motivated by this purpose, a series of amidoxime ligands and their analogs have been developed with high absorption capacity and selectivity. An in-depth understanding of the structural information of the uranyl-ligand complexes is essential to improve the performance of the ligands. Herein, we have studied the coordination of three amidoxime ligands (6-methoxyl-naphtha-2-amidoxime, NAO; glutarimidedioxime, GIO; and gluardiamidoxime, GDO) with uranyl in the gas phase by mass spectrometry. The identifications of the electrospray ionization (ESI) generated species, the fragmentation pathways upon dissociation, the relative binding affinities of the ligands, and the hydration reactions have been conducted and compared to reveal their structural information in the gas phase. The binding modes for all the complexes were suggested based on the experimental results and were further studied by density functional theory (DFT) calculations.

Efficient Synthesis of 1,5-Disubstituted Carbohydrazones Using K2CO3 As a Carbonyl Donor

A novel reaction that generates 1,5-disubstituted carbohydrazones via the carbonylation of tosylhydrazones has been developed. For the first time, the inexpensive, readily available, environmentally friendly, and nongaseous potassium carbonate is used as the carbonyl donor for the transformation. The reaction system exhibited tolerance with various functional groups and affords the desired products in good to excellent yields. This reaction is expected to be a powerful tool for the synthesis of carbohydrazone compounds.

Promising density functional theory methods for predicting the structures of uranyl complexes

The structural parameters of uranyl complexes may provide important hints for understanding the electronic structure of the U–X (ligand) bond. The present study aims to identify a reliable theoretical method to simulate the structures of different uranyl complexes. Examining the performance of different relativistic effective core pseudopotentials (RECPs) and different density functional theory (DFT) methods, we found that the overall performances of BB1K/(SDD-MWB60:6-311G(d,p)) (M2-B1) and LC-BLYP/(SDD-MWB60:6-311G(d,p)) (M7-B1) methods are better than all the other examined ones (including the popular B3LYP method). Good linear correlations have been achieved between the calculation results with M2-B1 or M7-B1 and the experimental ones (X-ray crystal structure). The R2 values of both these methods are about 0.985, and the SD values are both about 0.05 A for 68 U–X bond distances. On this basis, the preliminary ligand structure-binding ability analysis of U–O bonds and the elucidation of the binding mode of the azide group in the concerned U–N(azide) compound have been provided.

The enhanced uranyl–amidoxime binding by the electron-donating substituents

The enhanced binding of aryl amidoximes with uranyl due to the electron-donating substituents was identified by mass spectrometry, fluorescence quenching experiments, and theoretical calculations.

Stereocontrolled C(sp3)–P bond formation with non-activated alkyl halides and tosylates

The C(sp3)–P bond is formed via the reaction between P–H compounds and non-activated alkyl electrophiles, especially secondary alkyl halides and tosylates. This reaction proceeds via an SN2 mechanism with inversion of configuration, so it can be used to form C–P bonds with stereocontrol from chiral secondary alcohols.

The Hydrolytic Stability and Degradation Mechanism of a Hierarchically Porous Metal Alkylphosphonate Framework

To aid the design of a hierarchically porous unconventional metal-phosphonate framework (HP-UMPF) for practical radioanalytical separation, a systematic investigation of the hydrolytic stability of bulk phase against acidic corrosion has been carried out for an archetypical HP-UMPF. Bulk dissolution results suggest that aqueous acidity has a more paramount effect on incongruent leaching than the temperature, and the kinetic stability reaches equilibrium by way of an accumulation of a partial leached species on the corrosion conduits. A variation of particle morphology, hierarchical porosity and backbone composition upon corrosion reveals that they are hydrolytically resilient without suffering any great degradation of porous texture, although large aggregates crack into sporadic fractures while the nucleophilic attack of inorganic layers cause the leaching of tin and phosphorus. The remaining selectivity of these HP-UMPFs is dictated by a balance between the elimination of free phosphonate and the exposure of confined phosphonates, thus allowing a real-time tailor of radionuclide sequestration. Moreover, a plausible degradation mechanism has been proposed for the triple progressive dissolution of three-level hierarchical porous structures to elucidate resultant reactivity. These HP-UMPFs are compared with benchmark metal-organic frameworks (MOFs) to obtain a rough grading of hydrolytic stability and two feasible approaches are suggested for enhancing their hydrolytic stability that are intended for real-life separation protocols.

Pd-Catalyzed Vinylation of Aryl Halides with Inexpensive Organosilicon Reagents Under Mild Conditions

Pd-catalyzed Hiyama vinylation reaction of non-activated aryl chlorides and bromides under mild conditions was developed. The use of efficient vinyl donors and electron-rich sterically hindered phosphine ligands was critical for the success of the reaction. The products of this transformation can be used for Am/Cm separation, an important challenge in nuclear fuel reprocessing. The substituent effect on Am/Cm separating selectivity was also achieved, which could contribute to the development of new chromatographic materials for the separation of Am and Cm.