Synthesis and Crystal Structure of a Tetravalent Cerium Complex with a Bridging Triphenolate Ligand

Reaction of（NH4）2 Ce（NO3）6 first with NaOtBu in a 1：6 molar ratio in THF, then with an equivalent of 2-bis（salicylidieneamino）methylphenol（H3 salmp） affords the（salmp）2 Ce2-（O）Na4（OtBu）4（THF）4 ·2C6 H6 complex. It crystallizes in monoclinic, space group C2/c with a = 16.5218（14）, b = 23.992（2）, c = 21.9454（18）, β = 97.470（1）°, V = 8625.1（12）3, Z = 4, Mr = 1811.96, Dc = 1.395 g/cm3, μ = 1.126 mm-1, F（000） = 3736, S = 1.061, R = 0.0405 and wR = 0.0932（I 〉 2σ（I））.

Synthesis and Crystal Structure of the First Guanidinate Complex of Tetravalent Cerium

Reaction of Ce（O-t-Bu）2（NO3）2 and sodium guanidinate GuaNa （Gua-=TMS2NC（NC6H11）2-） in THF affords the first guanidinate Ce（IV） complex of Ce2（O-t-Bu）7（Guaˊ） （1, Gua-=（C6H11NH）C（NC6H 11）（NH）-）. It crystallizes in monoclinic, space group P21/n with a=15.2937（14）, b=17.8409（16）, c=19.0454（16）, β=97.713（2）°, V=5149.6（8）3 , Z=4, Mr=1014.38, Dc=1.308 g/cm3 , μ=1.787 mm-1 , F（000）=2104, S=1.015, R=0.0451 and wR=0.0901 （I 〉 2σ（I））. In the reaction the cleavage of TMS-N bonds happened unexpectedly.

Synthesis and Characterization of Tetravalent Cerium Complexes with p-Tert-butylcalix[n]arenes (n=4, 6, 8)

Three Ce 4+ complexes Ce(p tert butylcalixarene)·(dmf) 4·H 2O (complex A), Ce(p tert butylcalixarene) 2·(dmf) 10 (complex B) and Ce(p tert butylcalixarene)·(dmf) 4 (complex C) were prepared from N,N dimethylforamide (dmf) solution of Ce(NO 3) 3. Their thermal stability, optical properties and coordination features were investigated with thermogravimetric and differential thermal analysis, ultraviolet and visible spectrophotometer, fluorescence spectrophotometer, infrared spectroscopy, and 1H NMR spectrometer. In the solvents of C 6H 6, 1,2 dichloroethane and dmf, complexes A and B can exhibit a ligand to metal charge transfer transition lying in ca. 20000 cm -1 in the electronic spectra. Complex A displays a dimeric structure in C 6D 6 solution. Ce 4+ ions in the complexes are coordinated by phenolic groups of the ligands, oxygen atoms of dmf molecules, and / or OH - ions.

A spike-trimer protein-based tetravalent COVID-19 vaccine elicits enhanced breadth of neutralization against SARS-CoV-2 Omicron subvariants and other variants

Multivalent vaccines combining crucial mutations from phylogenetically divergent variants could be an effective approach to defend against existing and future SARS-Co V-2 variants.In this study,we developed a tetravalent COVID-19 vaccine SCTV01E,based on the trimeric Spike protein of SARS-Co V-2 variants Alpha,Beta,Delta,and Omicron BA.1,with a squalenebased oil-in-water adjuvant SCT-VA02B.In the immunogenicity studies in na?ve BALB/c and C57BL/6J mice,SCTV01E exhibited the most favorable immunogenic characteristics to induce balanced and broad-spectrum neutralizing potencies against pre-Omicron variants(D614G,Alpha,Beta,and Delta)and newly emerging Omicron subvariants(BA.1,BA.1.1,BA.2,BA.3,and BA.4/5).Booster studies in C57BL/6J mice previously immunized with D614G monovalent vaccine demonstrated superior neutralizing capacities of SCTV01E against Omicron subvariants,compared with the D614G booster regimen.Furthermore,SCTV01E vaccination elicited na?ve and central memory T cell responses to SARS-Co V-2 ancestral strain and Omicron spike peptides.Together,our comprehensive immunogenicity evaluation results indicate that SCTV01E could become an important COVID-19 vaccine platform to combat surging infections caused by the highly immune evasive BA.4/5 variants.SCTV01E is currently being studied in a head-to-head immunogenicity comparison phase 3 clinical study with inactivated and m RNA vaccines(NCT05323461).

Tetravalent Terbium Chelates: Stability Enhancement and Property Tuning

Coordination chemistry of rare-earth elements has been dominated by the+3 oxidation state.Complexes with higher-valence lanthanide ions are synthetically challenging but are of fundamental research interest and significance as advanced molecular materials.Herein,four tetravalent terbium complexes(2-5)of the common formula[Tb(OSiPh3)4L](L=ethylene glycol dimethyl ether(DME),2,2’-bipyridine(bpy),2,2’-bipyrimidine(bpym),and 1,10-phenanthroline(phen))are reported.Crystallographic analyses reveal in each of these complexes a hexacoordinate Tb(IV)ion situated in a distorted octahedral coordination environment formed by four triphenylsi-loxido ligands and a bidentate chelating ligand.The use of chelating ligands enhances the stability of the resulting complexes over their THF solvate precursor.More significantly,the aromatic N-chelating ligands have been found to tune effectively the electronic structures of the complexes,as evidenced by the sizable potential shifts observed for the quasi-reversible redox Tb(IV/III)process and by the changes in their absorption spectra.The experimental findings are augmented with quantum theoretical calculations in which the ligandπ-donation to the 5d orbitals of the Tb(IV)center is found to be primarily responsible for stability enhancement and the corresponding changes of physical properties observed.Magnetic measurements and results from electron paramagnetic resonance studies produced small absolute values of zero-field splittings of these complexes,ranging from 0.1071(22)to 1.1484(112)cm-1 and comparable to the values reported for analogous Tb(IV)complexes.

On Connected Tetravalent Cayley Graphs of a Non-abelian Group of Order 3p2

In this paper we determine all tetravalent Cayley graphs of a non-abelian group of order 3p2, where p is a prime number greater than 3, and with a cyclic Sylow p-subgroup. We show that all of these tetravalent Cayley graphs are normal. The full automorphism group of these Cayley graphs is given and the half-transitivity and the arc-transitivity of these graphs are investigated. We show that this group is a 5-CI-group.

Adsorption of Ce(Ⅳ) Anionic Nitrato Complexes onto Anion Exchangers and Its Application for Ce(Ⅳ) Separation from Rare Earths(Ⅲ)

Ce （Ⅳ） nitrato complexes were adsorbed on two anion exchangers based on polyvinyl pyridine （PVP） and quatemized PVP incorporated into porous silica matrix. The effect of nitric acid concentration （0.5～6 mol·L^-1） and temperature （278 ～318 K） on Ce（ Ⅳ ） sorption efficiency was investigated. Sorption increased with increasing nitric acid concentration, indicating that [Ce（NO3）6]^2- complex is the main adsorbed Ce（Ⅳ） species. Oxidation of sorbents by adsorbed Ce （ Ⅳ ） species resulting in Ce （ Ⅲ ） release to the solution was observed. Pyridine based anion exchangers exhibited higher oxidation stability compared to the commercial strong base anion exchanger. Ce（ Ⅳ ） reduction was temperature dependent and obeyed pseudo-first-order reaction kinetics. Column separation of Ce （ Ⅳ ） from La （ Ⅲ ） and Y （ Ⅲ ） was carried out from 6 mol·L^-1 nitric acid with PVP based anion exchanger. Reasonable Ce （Ⅳ） breakthrough capacity （0.7 mol·kg^-1 PVP） was achieved. No remarkable decrease of capacity was observed within 3 consequent runs. In contrast, Ce （Ⅲ） leakage due to reduction decreased and breakthrough capacity slightly increased. This effect was more pronounced with increasing temperature. Regeneration with 0.1 mol·L^- 1 nitric acid was successful （recovery 100% ± 4% ） and Ce solution of high purity （ 〉 99.97% ） with respect to La and Y content was gained.

Clinical development update: 1st dengue vaccine candidate

A candidate tetravalent dengue vaccine is being assessed in three clinical trials involving more than 35,000 children between the ages of 2 and 16 years in the Asia-Pacific and Latin American countries.We report the results of long-term follow-up interim analyses and integrated efficacy analyses.We are assessing the incidence of hospitalization for virologically confirmed dengues a surrogate safety end point during follow-up in years 3–6 of two phase 3 trials,CYD14 and CYD15,and a phase 2b trial,CYD23/57.We estimated vaccine efficacy using pooled data from the first 25 months of CYD14 and CYD15.

Epimorphisms between Finite 4-Valued Modal Algebras

In this paper, we determine conditions for the existence of an epimorphism between two finite 4-valued modal algebras and state a method to obtain it. Furthermore, we obtain formulas which generalize those indicated by R. Sikorski for finite Boolean algebras [1] 08D0C9EA79F9BACE118C8200AA004BA90B02000000080000000E0000005F005200650066003300380037003200340036003100310038000000 , and by M. Abad and A. V. Figallo for finite 3-valued ukasiewicz algebras [2] 08D0C9EA79F9BACE118C8200AA004BA90B02000000080000000E0000005F005200650066003300380037003200340036003100320031000000 .

Glutathione-depleted cyclodextrin pseudo-polyrotaxane nanoparticles for anti-inflammatory oxaliplatin(Ⅳ) prodrug delivery and enhanced colorectal cancer therapy

Oxaliplatin(Oxa) is the first-line chemotherapeutic drug for the treatment of colorectal cancer(CRC). However, long-term Oxa chemotherapy can induce inflammation and increase the levels of cyclooxygenase-2(COX-2) and prostaglandin E2(PGE2), which can promote tumor metastasis. Moreover,high glutathione(GSH) levels in CRC cells significantly reduce Oxa sensitivity and seriously restrict the clinical application of Oxa. Herein, an Oxa(Ⅳ) prodrug with anti-inflammatory properties(desmethyl naproxe, DN) and GSH-depleting cyclodextrin pseudo-polyrotaxane carriers were prepared and further self-assembled into micellar nanoparticles(designated DNPt@PPRI). The relesae of DN from DNPt@PPRI can reduce the level of PGE2 to inhibit inflammation and tumor metastasis by decreasing COX-2 protein,and also synergize with Oxa to inhibit tumor. More importantly, GSH depletion can reduce the detoxification of Oxa and further enhance chemotherapy-induced apoptosis. DNPt@PPRI have a good GSH depletion ability to enhance the sensitivity of Oxa, indicating a potential in the synergistic chemotherapy and chemo-sensitization of colorectal cancer.

Insights into the stable and fast lithium storage performance of oxygen-deficient LiV_(3)O_(8) nanosheets

Oxygen-deficient LiV_(3)O_(8) is considered as one of the promising cathode materials for lithium ion batteries(LIBs)because of its high cycling stability and rate capability.However,it is very difficult to control and study the content and position of V^(4+)and oxygen vacancies in LiV_(3)O_(8),and therefore the mechanism of improving electrochemical performance of LiV_(3)O_(8) is still unclear.Herein,we developed four LiV_(3)O_(8) nanosheets with different V^(4+)and oxygen vacancy contents and positions.The physicochemical and lithium storage properties indicate that the V^(4+)and oxygen vacancies in the surface layer increase the contribution of pseudocapacitive lithium storage on the nanosheet surface.The V^(4+)and oxygen vacancies in the lattice improve the electrical conductivity of LiV_(3)O_(8),and enhance the phase transformation and lithium ion diffusion rates.By adjusting the content of V^(4+)and oxygen vacancies,we obtained an oxygen-deficient LiV_(3)O_(8) nanosheet which maintained more than 93%of the initial reversible capacity after 300 cycles at 5,000 mA·g^(−1).The V^(4+)and oxygen vacancies play an important role in improving the stability and rapidity of lithium storage.This work is helpful to understand the stable and fast lithium storage mechanism of oxygen-deficient LiV_(3)O_(8),and might lay a foundation for further studies of other oxygen-deficient metal oxide electrodes for long-life and high-power LIBs.

A GSH-depleted platinum(Ⅳ) prodrug triggers ferroptotic cell death in breast cancer

Cisplatin is the first-line drug for treatment of various solid tumors including breast cancer due to the broad anti-tumor spectrum and strong anti-tumor effect.However,serious side effects and long-term medication of reduced sensitivity by high GSH in tumor cells have severely restricted its further clinical application.Herein,a GSH-depleted Pt(Ⅳ)prodrug(Platin B)based on cisplatin and 4-carboxylphenylboronic acid pinacol ester was prepared to solve the problems.As an excellent GSH scavenger,4-carboxylphenylboronic acid pinacol ester could be activated by intracellular redox reactions to release quinone methide,thereby amplifying oxidative stress and leading to breast cancer ferroptosis therapy.Interestingly,the consumption of GSH can also reduce cisplatin inactivation,enhance the sensitivity of tumor cells to cisplatin and efficiently induce apoptosis/ferroptosis.This work highlights the use of GSH scavenger for triggering ferroptotic cell death in breast cancer.