Ultraviolet photofragmentation spectroscopy of metal dication sandwich complexes in the gas phase combined with DFT/TDDFT calculations

Metal dication-ligand sandwich complexes have attracted intense attention recently for their widely use in catalysis, biochemistry and material science. The experimental techniques developed by our group have allowed forming, confining, cooling and investigating a wide range of metal dication complexes in the gas phase. In this thesis, the ultraviolet photofragmentation studies of Pb(II), Cu(II) and Ca(II) sandwich complexes with aromatic ligands are performed using a hybrid quadrupole ion trap instrument, followed by DFT/TDDFT calculations. The experimental results indicate that the complexes are capable of yielding structured, sometimes conformation resolved, UV spectra. The spectra of metal dication-benzene complexes exhibit features in the wavelength range 220-270 nm and a big raise as the wavelength decreases. The lead dication-bis(toluene) complex spectrum shows some well-resolved features arising from different conformers. The theory suggests that all of these complexes have excitations including significant contributions from the metal-based orbital. The adiabatic TDDFT methodology is able to give reasonable agreement between the calculated excitations and the experimental spectra for the close-shell complexes. But for some open-shell complexes, the calculated excitations are spin contaminated, which need to be discarded or corrected in the future. The degree of spin contamination for selected excitations is qualified by calculating the values. For lead and calcium open-shell complexes, most of the excitations that can match the experimental features can be trusted. However, for the copper open-shell complex, only three states are ~90% doublet in their character which are responsible for some excitations that can match the spectra. Challenges such as developing the theory to describe the open-shell system and refining the experimental techniques to improve the resolution of the spectra, still remain

Ultraviolet photofragmentation spectroscopy of metal dication sandwich complexes in the gas phase combined with DFT/TDDFT calculations

Metal dication-ligand sandwich complexes have attracted intense attention recently for their widely use in catalysis, biochemistry and material science. The experimental techniques developed by our group have allowed forming, confining, cooling and investigating a wide range of metal dication complexes in the gas phase. In this thesis, the ultraviolet photofragmentation studies of Pb(II), Cu(II) and Ca(II) sandwich complexes with aromatic ligands are performed using a hybrid quadrupole ion trap instrument, followed by DFT/TDDFT calculations. The experimental results indicate that the complexes are capable of yielding structured, sometimes conformation resolved, UV spectra. The spectra of metal dication-benzene complexes exhibit features in the wavelength range 220-270 nm and a big raise as the wavelength decreases. The lead dication-bis(toluene) complex spectrum shows some well-resolved features arising from different conformers. The theory suggests that all of these complexes have excitations including significant contributions from the metal-based orbital. The adiabatic TDDFT methodology is able to give reasonable agreement between the calculated excitations and the experimental spectra for the close-shell complexes. But for some open-shell complexes, the calculated excitations are spin contaminated, which need to be discarded or corrected in the future. The degree of spin contamination for selected excitations is qualified by calculating the values. For lead and calcium open-shell complexes, most of the excitations that can match the experimental features can be trusted. However, for the copper open-shell complex, only three states are ~90% doublet in their character which are responsible for some excitations that can match the spectra. Challenges such as developing the theory to describe the open-shell system and refining the experimental techniques to improve the resolution of the spectra, still remain

Clinicopathologic analysis of nodal T-follicular helper cell lymphomas, a multicenter retrospective study from China

BackgroundNodal T-follicular helper cell lymphomas (nTFHLs) represent a new family of peripheral T-cell lymphomas (PTCLs), and comparative studies of their constituents are rare.MethodsThis study retrospectively enrolled 10 patients with nTFHL-F and 30 patients with nTFHL-NOS diagnosed between December 2017 and October 2023 at six large comprehensive tertiary hospitals; 188 patients with nTFHL-AI were diagnosed during the same period at the First Affiliated Hospital of Zhengzhou University for comparison.ResultsCompared with nTFHL-AI, nTFHL-NOS patients exhibited better clinical manifestations, lower TFH expression levels, and a lower Ki-67 index. However, no differences in clinicopathological features were observed between nTFHL-F and nTFHL-AI patients as well as nTFHL-NOS patients. According to the survival analysis, the median OS for patients with nTFHL-NOS, nTFHL-AI, and nTFHL-F were 14.2 months, 10 months, and 5 months, respectively, whereas the median TTP were 14 months, 5 months, and 3 months, respectively. Statistical analysis revealed differences in TTP among the three subtypes(P=0.0173). Among the population of patients receiving CHOP-like induction therapy, there were significant differences in the OS and TTP among the nTFHL-NOS, nTFHL-AI, and nTFHL-F patients (P=0.0134, P=0.0205). Both the GDPT and C-PET regimens significantly improved the ORR, OS, and PFS in nTFHL patients.ConclusionThere are significant differences in the clinical manifestations, pathology, and survival outcomes among the three subtypes of nTFHLs. However, further research with a larger sample size, and involving clinical pathology and molecular genetics is needed to determine the distinctive biological characteristics of these tumors

Synthesis of porphyrins, chlorins and bacteriochlorins by chemical modifications of chlorophyll a

The goal of this project was to synthesize new porphyrins, chlorins and bacteriochlorins via chemical modifications of chlorophyll a so that new chemistry and applications of chlorophyll a and its related derivatives could be developed. A magnesium-free yet stable derivative of chlorophyll a, 7, isolated from the blue alga Spirulina maxima, was employed as the common intermediate in this work. As the first objective, new methods of asymmetric hydroxylation and regioselective oxidation of chlorophyll derivatives were successfully developed. Stereoselective synthesis of natural antioxidative chlorins 81, 82(S), 82(R), 83(R), 84 and 102, isolated from marine metabolites, was performed in a short and effective way. This biomimetic synthetic approach helped to elucidate the possible biogenetic evolution of these antioxidative chlorins from chlorophyll a. The second objective of this work was to design a method to convert chiorin 112 into porphyrin 114. A novel and effective acid-catalyzed tautomerization reaction was discovered and optimized, which has provided a new view on the migration of hydrogens in the saturated ring IV to the exocyclic ring V. The porphyrins so produced were used as intermediates for the further preparation of chlorophyll related petroporphyrins and regiochemically-pure benzoporphyrin derivatives (BPD5). Making use of the aforementioned tetrapyrrolic materials, the third objective of this work was to develop new photosensitizers for photodynamic therapy of tumors. New monovinylporphyrins and an [A,C]-divinylporphyrin 147 were synthesized. Diels-Alder reaction of these (di)vinylporphyrins with dimethyl acetylenedicarboxylate (DMAD) afforded new regiochemically-pure BPDs 125 and 141 and dibenzoporphyrin derivative 165. These new sensitizers have characteristics that meet or exceed the promising chemical features of benzoporphyrin derivative monoacid ring A (BPDMA), a second generation sensitizer in Phase-TI clinical trials. The final objective of this work was to exploit the nucleophilic behaviour of the bicyclic amidines, l,8-diazabicyclo[5.4.O]undec-7-ene (DBU) and 1,5-diazabicyclo- [4.3.O]non-5-ene (DBN). Two reactions were examined. Firstly, DBU acting as a difunctional nucleophile quantitatively reacted with DMAD to afford a fused tricyclic derivative 176. Secondly, 7, a weak electrophile which alone does not electrophilically react with DBU or DBN, has reacted, through catalytic activation by Lewis acids, with nucleophilic DBU and DBN to form chlorin e₆ amides 185 and 186. These results have brought about further understanding of the nucleophilicity as well as the basicity of these common organic bases. [chemical compound diagrams]Science, Faculty ofChemistry, Department ofGraduat

Hermite Expansion Model and LMMSE Analysis for Low-Resolution Quantized MIMO Detection

In this paper, the Hermite polynomials are employed to study linear approximation models of narrowband multiantenna signal reception (i.e., MIMO) with low-resolution quantizations. This study results in a novel linear approximation using the second-order Hermite expansion (SOHE). The SOHE model is not based on those assumptions often used in existing linear approximations. Instead, the quantization distortion is characterized by the second-order Hermite kernel, and the signal term is characterized by the first-order Hermite kernel. It is shown that the SOHE model can explain almost all phenomena and characteristics observed so far in the low-resolution MIMO signal reception. When the SOHE model is employed to analyze the linear minimum-mean-square-error (LMMSE) channel equalizer, it is revealed that the current LMMSE algorithm can be enhanced by incorporating a symbol-level normalization mechanism. The performance of the enhanced LMMSE algorithm is demonstrated through computer simulations for narrowband MIMO systems in Rayleigh fading channels

A Low-Complexity Structure for Multi-user Massive MIMO with Binary Arrary-Receiver Based on Constructive Noise

In this paper, single-input multiple-output (SIMO) system when employing massive binary array-receiver has been investigated while constructive noise has been observed in the single user system to detect the higher-order QAM modulated signals. To fully understand the interesting phenomenon, mathematical model has been established and analyzed in this paper. Theorems of the signal detectability are studied to understand the best operating signal-to-noise ratio (SNR) range based on the error behaviours of the single user SIMO system. Within the observation and analysis, a novel new multiuser SIMO with binary array-receiver structure has been proposed and can be considered as a solution to deal with the high complexity problem that the traditional model has when using maximum likelihood (ML) detection. The key idea of this approach is to set up the multiuser multiple-input multiple-output (MIMO) model into a frequency division multiple access (FDMA) scenario and regard each user as single user SIMO to achieve the goal of decreasing the exponentially increased complexity of ML detection method to the number of users. It is shown by numerical results that each user in this system can achieve a promising error behaviour in the specific best operating SNR range