We present the syntheses and crystal structures of several adventitious hydrolysis products of UCl₄, UBr₄, UBr₅, and UO₂Cl₂. We obtained compounds containing dinuclear μ-O-bridged uranium(IV) cations, mixed-valent uranyl(V)-uranyl(VI) tetra- and octanuclear complex cations, and also a compound where the isoelectronic species UO₂ ²⁺ and UN₂ formed a complex.

Abstract

UCl₄, UBr₄, UBr₅, or UO₂Cl₂ reacted with excess liquid ammonia – in adventitious presence of moisture and/or air – and formed some peculiar uranium compounds of which we present the crystal structures. [(NH₃)₇(N₃)U(μ-O)U(NH₃)₈]Cl₅ ⋅ 7NH₃ contains a dinuclear μ-O-bridged uranium(IV) cation, [{(NH₃)₄UO₂}₂(μ-O)]Cl₂ ⋅ 4NH₃ features a dinuclear μ-O-bridged uranyl(VI) cation, while the compounds [(U(VI)O₂)₂(U(V)O₂)₂(μ₃-O)₂(NH₃)₁₂]Br₂ ⋅ 6NH₃ and [(U(VI)O₂)₄(U(V)O₂)₄(μ₃-O)₄(NH₃)₂₂]Br₄ ⋅ 16NH₃ are mixed-valent containing uranyl(V)-uranyl(VI) units. For these tetra- and octanuclear complex cations we observed that the O atoms of the uranyl(V) units can be μ₂- and even μ₃-bridging to uranyl(VI) units, while the O atoms of the latter are acting as terminal ligands only. [(NH₃)₈U(μ-N)U(NH₃)₅(μ-N)UO₂(NH₃)₄]Br₆ ⋅ 18NH₃ presents the first example of a compound where the isoelectronic species UO₂ ²⁺ and UN₂ formed a complex with the NUN unit bridging to the U atom of the uranyl(VI) cation. As it is can be difficult to distinguish between N and O atoms with X-ray diffraction, quantum-chemical calculations at the DFT-PBE0/TZVP level of theory were carried out which unequivocally confirmed the atom assignments in the crystal structures. The chemical bonding in the complex cations was studied using intrinsic bonding orbitals and allowed for an additional discrimination of the U(V) and U(VI) atoms in the mixed-valent compounds.

The Cover Feature shows construction machinery actively engaged in a distibene project. The picture refers to a compound bearing the highly encumbered Ar* ligand (Ar* = C₆H₂−2,6-(CHPh₂)₂−4-iPr), which was isolated from salt-free metathesis reactions – alongside other novel dipnictenes – during this study. The distibene shown at the construction site protrudes from other compounds of this class, as it exhibits the currently longest Sb=Sb distance [2.8605(5) Å] of all thus far reported distibenes. “Construction” of dipnictenes with elongated bonds between the heavier atoms is currently of great interest in the research community, as such compounds are promising candidates for the application in the controlled activation of small molecules. More information can be found in the Research Article by R. C. Fischer and co-workers.

The air-stable dipyrromethene-based tin complexes (SNDIPYs) 1 and 3 and the first isolable ASDIPY 2, which are direct analogues of BODIPY, have been synthesized and fully characterized. All of these complexes exhibit green photoluminescence.

Abstract

Boron-dipyrromethenes (BODIPYs) have attracted much attention owing to their unique properties and widespread applications; however, the incorporation of the heavier group 14 and 15 elements in the rigid dipyrromethene ligands remains limited. Herein, the dipyrromethene-based heavier group 14 and 15 element complexes, tin-dipyrromethene (SNDIPY, 1) and arsenic-dipyrromethene (ASDIPY, 2), which are direct analogues of BODIPY, have been facilely synthesized and isolated in moderate yields. Both compounds have been investigated by NMR, UV-vis absorption, photoluminescence spectroscopy, cyclic voltammogram, X-ray crystallography, as well as theoretical studies. Both compounds exhibit green photoluminescence. Notably, SNDIPY 1 is air-stable and compound 2 represents the first isolable and structurally characterized ASDIPY.

Salicylates influencing High valent Mn^V=O at room temperature: This work provides an alternate path to generate transient reactive Mn^V=O species under stoichiometric conditions. The studies involved highlight the pivotal role of bound 5-X-salicylate moieties on the Mn^V=O species exhibiting a significant effect on its electrophilicity. Besides, the employed complexes are potent to prevent the proliferation of cancer cells effectively and are mapped to the oxidative mechanism of action.

Abstract

An alternative and efficient route has been derived to generate the high valent [Mn(V)=O(m-Cl-salicylate)]⁺ intermediates with a series of non-heme neutral ligand frameworks at 20 °C. The current method provides an advantage with feasibility in maintaining stoichiometric oxidant ratios along with the crucial variations of the salicylate moieties in tuning the reactivity of Mn(V)=O species. An in-depth analysis of the Hammett studies revealed that the bound 5-X-salicylate (X=Cl, and NO₂) drastically alters the corresponding Mn(V)=O's reactivity rates. In contrast, variations in the parent ligand frameworks resulted in consistent ρ values with increased lifetimes depicting the ligand's role in stabilization. Lastly, the complexes have been characterized to promote oxidative stress and prevent the proliferation of cancer cells effectively.

The Front Cover shows main group dichalcogeniranes bearing three-membered rings composed of one main group atom and two group 16 atoms. Such three-membered-ring compounds appear to be unstable because of their highly strained structures and the electronic repulsion between the lone-pair electrons of two group 16 atoms incorporated into the rigid structures. However, very recently, stable compounds were characterized by X-ray diffraction analysis on many occasions, revealing unique molecular structures with very long chalcogen−chalcogen single-bonds in some cases. Accordingly, it is time to highlight recent advances in the preparation and reactivity of main group analogs of dichalcogeniranes. More information can be found in the Review by M. Saito and co-workers.

The structural, electronic, optical properties and its structure-property relationship of molybdenyl carbonate Cs₃MoO₄(HCO₃) with NLO active functional units are studied through theoretical perspectives.

Abstract

Employing functional building units with microscopic second-order NLO response has been proposed to explore high performance NLO materials. Herein, structural, electronic and optical properties of non-centrosymmetric molybdenyl carbonate Cs₃MoO₄(HCO₃) with NLO active functional units have been examined based on density functional theory. Theoretical results are consistent with experimentally mentioned data, confirming the reliable method. Detailed geometric structure, electronic attributes, linear optical properties, and nonlinear optical properties of Cs₃MoO₄(HCO₃) are provided. Analysis of structures, compositions of bands and plots of charge density suggest that asymmetric functional building units [MoO₄] and [HCO₃] exhibit varying degrees of second-order Jahn-Teller distortions, and therefore have a significant impact on the electronic structure and optical properties of Cs₃MoO₄(HCO₃). Maximum absolute value of SHG coefficients at 1064 nm is 0.671 pm/V for d ₁₅, which is nearly twice as much as that of KDP. Further researches are needed in future to validate and enhance optical anisotropy characteristic of Cs₃MoO₄(HCO₃) for satisfying the phase matching conditions. Analysis results indicate that microscopic origins of SHG response in Cs₃MoO₄(HCO₃) are complicated, such as geometric environment, induced polar asymmetric functional building units, and electronic properties. Continuous research on structure-property relationship of NLO materials is needed for exploring more competitive NLO materials.

The intermolecular insertion reactions of small molecules into P−P bonds of oligophosphorus compounds are described. This type of reactivity is important for the development of new, targeted and selective methods for the activation of oligophosphorus compounds to obtain new oligophosphorus ligands and materials.

Abstract

The insertion of unsaturated organic molecules into a P−P bond of oligophosphorus compounds has the potential to expand the organophosphorus and organometallic chemistry and to make it more variable with the selective formation of desirable products. This article reviews the insertion reaction for oligophosphorus compounds and focuses in particular on non-metals, unsaturated organic substrates, carbenes and carbene analogues as starting reagents.

Cobalt was successfully doped into the lattice of unique ZnO platelets for the first time. Huge reductions in photocatalytic activity (PCA) were observed compared to that of undoped powders in UVA, UVB, and UVC regions. PCA reduction was explained via tracking the surface hydroxyl groups using XPS analyses.

Abstract

Platelet-shaped zinc oxide (ZnO) particles exhibit certain advantages compared to conventional micron and nano forms. Their superior surface coverage and excellent optical properties make these particles very attractive as UV filters in cosmetics and personal care applications. Although ZnO is non-toxic, it exhibits photocatalytic activity (PCA), which increases when the size of particles approaches the nanoscale. High PCA of mineral/inorganic filters is not desired in cosmetics and personal care applications. Therefore, it is essential to develop strategies to reduce PCA of such materials under UV exposure. Accordingly, the research objective of this study is to develop an understanding of the effects of Co-doping on the optoelectronic and crystal structure of platelet shaped ZnO particles with Zn_1-xM_xO stoichiometry (x=0-4 wt % cobalt). XRD-based Rietveld refinement and WD-XRF reveal that Co was successfully doped into the ZnO lattice. SEM and particle size analyses confirmed that the shape and size of the designed ZnO platelets did not change significantly after doping. ~85 % reduction in PCA has was achieved by 3 wt % Co doping which was attributed to reduced OH and O₂ free radical concentration. These results clearly show that Co-doping can be used to effectively tailor the bandgap and optical properties of the designed ZnO particles.

Gold nanorods coated with PEG or SiO₂ and mixed with pheophorbide a are bactericidal. The efficiency of singlet oxygen generation varied depends on the type of PEG polymer used for coating nanorods. The most effective against bacteria are the mixtures of PEG-coated nanorods with pheophorbide a, exposed to irradiation, which provides a >5.8 log reduction in the bacterial growth.

Abstract

The paper reports on the synthesis and evaluation of photochemical properties of gold nanorods (Au−NRs) coated with PEG with a thiol (−SH) group or SiO₂ and their physical mixtures with pheophorbide a. Also biological activity of these systems was tested in photodynamic therapy directed towards Staphylococcus aureus. The potential additive effect between differently functionalized Au−NRs and the dye pheophorbide a was also studied. The efficiency of singlet oxygen generation varied considerably depending on the type of PEG polymer used for coating NRs and was the highest, of 65%, for the polymer PEG (10k) and the Au−NRs concentration of (1.33×10⁻¹¹ M). For the other studied PEGs (2k, 5k) and the same concentration of NRs, a decrease in the singlet oxygen generation efficiency was observed. The most effective against Gram-positive bacteria were the mixtures of PEG-coated Au−NRs with pheophorbide a, exposed to irradiation at 405 nm and 660 nm, which provided a >5.8 log reduction in the bacteria growth. However, no strong bactericidal effect was noted in the case of irradiation with 525 nm.

H₂L (L=1-(4-carboxyphenyl)-1H-pyrazole-3-carboxylic acid) and Cd²⁺ ions were self-assembled by solvothermal method to prepare the coordination polymer 1 with 1D chain structure. 1 has dual-channel specific recognition ability for moxifloxacin (MXF) and silicate (SiO₃ ²⁻), which can be used as the turn-off sensing material for their detection. 1 is currently the second CP-based fluorescent sensor for MXF detection, and has the best sensing performance, with a sensitivity increase of more than three times. At the same time, as the first CP-based sensor material for detecting SiO₃ ²⁻, 1 shows excellent sensing properties and the limit of detection (LOD) is 0.68 μM.

Abstract

A 1D coordination polymer (CP) [Cd₂L₂(H₂O)₄] ⋅ 3H₂O (1) was prepared by solvothermal method using 1-(4-carboxyphenyl)-1H-pyrazole-3-carboxylic acid (H₂L) as single ligand. Fluorescence sensing experiments show that 1 has dual-function specific recognition ability for moxifloxacin (MXF) and silicate (SiO₃ ²⁻), which can be used as the turn-off sensing material for their detection. When 1 specifically identifies MXF, the Ksv is as high as 6.46×10⁵ M⁻¹ (6–20 μM) and the limit of detection (LOD) is as low as 14 nM. 1 is the second example of a CP-based fluorescent probe for the detection of MXF, which has confirmed that the Ksv is the largest to date for the detection of MXF, with a detection sensitivity increase of more than three times. For SiO₃ ²⁻ ions detection, the fluorescence intensity ratio has a good linear correlation with the concentration of SiO₃ ²⁻ ions in the concentration range of 0–100 μM, with a slope of 1.33×10⁴ M⁻¹, and the LOD is as low as 0.68 μM. According to the reported literature, 1 is the only example of SiO₃ ²⁻ ions sensing by CP-based fluorescence sensor so far. In order to better understand the sensing phenomenon, we also discussed the sensing mechanism for MXF and SiO₃ ²⁻ ions.