Many studies report the synthesis and characterizations of CeO 2 nanoparticles (NPs) due to their applications in catalysis, energy storage, or biomedical fields. In this study, we report a comprehensive interpretation of X-ray measurements on a series of oxo-hydroxo polynuclear Ce complexes whose atomic structures are resolved. The set of investigated samples represent the formation of CeO 2 small nanoparticles from a few Ce ions. Such clusters might serve as good building blocks in nanoscale architectures, and many clusters together may perform as highly active small particles. Therefore, the set of Ce clusters with growing size (from 0.6 to 1.2 nm) and nuclearity (from 6 to 38 Ce atoms) were synthesized and characterized by single-crystal X-ray diffraction (XRD), high-energy X-ray scattering (HEXS), and high-energy-resolution fluorescence detection (HERFD) X-ray absorption spectroscopy (XAS) methods and compared to larger CeO 2 NPs and bulk CeO 2 . Methods reveal consistent trends as the size of the system grows from molecular Ce-{n} 2, 6, 24, 38, and 40 clusters to bulk CeO 2 . HEXS reveals a broadening in distribution for the short Ce−O bonds for the small clusters. Concomitantly, the HERFD-XAS performed at the Ce L III edge indicates a gradual splitting of the Ce 5d states as the core of the complexes becomes more CeO 2 -like. The experimental observations have been supported by electronic structure calculations, based on the crystallographic determination of the cluster structures. Theoretical simulations allow us to isolate the structural and electronic properties of individual Ce sites within clusters and mark the great difference between surface and core Ce atoms. It also shows how a combination of simulations from different sites results in the accurate reproduction of the corresponding experimental data. This approach based on the experimentally determined atomic coordinates of clusters was then successfully extended to model Ce L III edge HERFD-XAS spectra for larger CeO 2 NPs. By linking the atomic and electronic structures of Ce polynuclear complexes, CeO 2 nanoparticles, and bulk CeO 2 , this work extends the fundamental knowledge of Ce oxide nanomaterials and supports a better understanding and predictability of their electronic structure.

Correcting for anomalous dispersion is part of any refinement of an X-ray diffraction crystal structure determination. The procedure takes the inelastic scattering in the diffraction experiment into account. This X-ray absorption effect is specific to each chemical compound and is particularly sensitive to radiation energies in the region of the absorption edges of the elements in the compound. Therefore, the widely used tabulated values for these corrections can only be approximations as they are based on calculations for isolated atoms. Features of the unique spatial and electronic environment that are directly related to the anomalous dispersion are ignored, although these can be observed spectroscopically. This significantly affects the fit between the crystallographic model and the measured intensities when the excitation wavelength in an X-ray diffraction experiment is close to an element's absorption edge. Herein, we report on synchrotron multi-wavelength single-crystal X-ray diffraction, as well as X-ray absorption spectroscopy experiments which we performed on the molecular compound Mo(CO)6 at energies around the molybdenum K edge. The dispersive (f′) and absorptive (f′′) terms of the anomalous dispersion can be refined as independent parameters in the full-matrix least-squares refinement. This procedure has been implemented as a new feature in the well-established OLEX2 software suite. These refined parameters are in good agreement with the independently recorded X-ray absorption spectrum. The resulting crystallographic models show significant improvement compared to those employing tabulated values.

The new mercuric complex [Hg(HL) 2 Cl 2 ] incorporating salicylaldimine ligand (HL = 2-((pyridin-3-ylimino)methyl)phenol) was fabricated where the ligand molecules behaved in a monodentate manner via their pyridine nitrogen atoms. In addition to elemental characterization, X-ray crystallographic studies of the complex revealed its packing in a monoclinic crystal system (space group: I2/a, a = 13.4276(2) Å, b = 6.20950(10) Å, c = 27.7530 (4) Å, α = γ = 90 , and β = 98.1610(10)). Hydrothermal treatment of [Hg(HL) 2 Cl 2 ] with thioacetamide afforded HgS microparticles (HgS μPs; Brunauer-Emmett-Teller [BET] surface area = 6.205 m 2 /g, diameter = 196.53-259.13 nm, and average size = 213.27 nm), whereas these microparticles were transformed to nanoscaled HgS particles (HgS NPs; BET surface area = 14.380 m 2 /g, diameter = 58.87-90.56 nm, and average size = 72.78 nm) by the action of ultrasonication. The as-prepared HgS, HgS NPs in particular, afforded remarkable microbicidal activity against eight strains of filamentous and unicellular human pathogenic fungi and yeasts in comparison with cycloheximide. Remarkably, Aspergillus terreus grew up to 34.7 ± 1.88 mm in the absence of any fungicide, but HgS μPs, HgS NPs, and cycloheximide limited the fungal growth to 26 ± 0.94, 12.33 ± 1.6, and 28.3 ± 1.7 mm after incubation for 6 days. Besides, inhibition of Rhodotorula glutinis was of 7.6 ± 0.01 × 10 7 CFU/ml in control sample, but experiments included HgS μPs, HgS NPs, and cycloheximide limited the colony-forming units of R. glutinis to 4.2 ± 0.01 × 10 7 , 3.5 ± 0.02 × 10 7 , and 5.9 ± 0.05 × 10 7 CFU/ml.

The crystalline sponge method facilitates the X-ray structure determination of samples that do not crystallize or are too sparsely available to afford viable crystallization. By including these materials in a metal–organic framework, the structure of the guest molecules can be determined. Some of the inherent difficulties of this method are discussed and the use of Cu Kβ radiation is presented as a simple and effective means to improve the quality of the diffraction data that can be obtained from a sponge crystal.

Two antimony complexes {[Sb(L1)Cl2] C1 and [Sb(L2)Cl2] C2} with the thiosemicarbazone ligands {HL1 = 4-(2,4-dimethylphenyl)-1-((pyridin-2-yl)methylene)thiosemicarbazide and HL2 = 4-(2,5-dimethoxyphenyl)-1-((pyridin-2-yl)methylene)thiosemicarbazide} were introduced. The structures were elucidated on the basis of a CHNS analysis, spectroscopic techniques (UV-Vis and FT-IR), and DMF solution electrical conductivities. Single crystal X-ray diffraction analysis of complex C1 assigned the complex pseudo-octahedral geometry and triclinic P-1 space group. Only the ligand HL1 and its derived complex C1 displayed antifungal activities against Candida albicans and this activity was enhanced from 10 mm to 21 mm for the respective complex, which is the same activity given by the drug “Amphotericin B”. The ligands HL1 and HL2 gave inhibitions, respectively, of 14 and 10 mm against Staphylococcus aureus and 15 and 10 mm against Escherichia coli; however, complexes C1 and C2 increased these inhibitions to 36 and 32 mm against Staphylococcus aureus and 35 and 31 mm against Escherichia coli exceeding the activities given by the ampicillin standard (i.e., 21 mm against Staphylococcus aureus and 25 mm against Escherichia coli). Against MCF-7 human breast cancer cells, the IC50 values of HL1 (68.9 μM) and HL2 (145.4 μM) were notably enhanced to the values of 34.7 and 37.4 μM for both complexes, respectively. Further, the complexes induced less toxicity in normal BHK cells (HL1 (126.6 μM), HL2 (110.6 μM), C1 (>210.1 μM), and C2 (160.6 μM)). As a comparison, doxorubicin gave an IC50 value of 9.66 μM against MCF-7 cells and 36.42 μM against BHK cells.