The Cover Feature shows a common idiom and pattern in Chinese traditional culture - Shuanglong Xizhu, which are both ancient totem symbols and profound cultural representations. At the same time, this picture also celebrates the coming of the Chinese New Year, “Year of the Dragon”, where the dragon is the symbol of China, representing auspiciousness, majesty and strength, and also expressing people's good wishes for the new year. The two dragons in the picture represent the two nucleophilic centers on the P and O atoms, respectively, which play and compete around the “pearl” evolved from the substrates. The molecular structure at the bottom of the picture is the simplified molecule of dialkyl-2H-1,2-phosphasiliren-3-olate. More information can be found in the Research Article by L. Wang, Z. Li, and co-workers.

The Front Cover shows the various “flavours” of α-functionalized phosphine chalcogenides that can be generated from the hydrophosphorylation of C=O/N bonds. Even with multiple potential operative mechanisms such as a concerted [2+2] hydrophosphorylation, or a stepwise P(V)−P(III) tautomerization and subsequent nucleophilic attack, the resultant α-functionalized phosphine chalcogenide remains the same. Additionally, the separation and organization of each α-functionalized phosphine chalcogenide displays that each is distinctly unique and is treated as such throughout the course of the Review. More information can be found in the Review by J.-W. Lamberink-Ilupeju, P. J. Ragogna, and J. M. Blacquiere.

A series of triamidoamine complexes of uranium and thorium with N-SiPh₂Bu^t substituents are described, including chlorides, azides, cyclometallates.

Abstract

We report the synthesis and characterisation of thorium(IV), uranium(III), and uranium(IV) complexes supported by a sterically demanding triamidoamine ligand with N-diphenyl-tert-butyl-silyl substituents. Treatment of ThCl₄(THF)_3.5 or UCl₄ with [Li₃(Tren^DPBS)] (Tren^DPBS={N(CH₂CH₂NSiPh₂Bu^t)₃}³⁻) afforded [An(Tren^DPBS)Cl] (An=Th, 1Th; U, 1U). Complexes 1An react with benzyl potassium to afford the cyclometallates (Tren^DPBS _cyclomet) [An{N(CH₂CH₂NSiPh₂Bu^t)₂(CH₂CH₂NSiPhBu^tC₆H₄)}] (An=Th, 2Th; U, 2U). Treatment of 1An with sodium azide affords [An(Tren^DPBS)N₃] (An=Th, 3Th; U, 3U). Reaction of 3Th with potassium graphite affords 2Th. In contrast, 3Th reacts with cesium graphite to afford the doubly-cyclometallated (Tren^DPBS _d-cyclomet) ate complex [Th{N(CH₂CH₂NSiPh₂Bu^t)(CH₂CH₂NSiPhBu^tC₆H₄)}₂Cs(THF)₃] (4). In contrast to 3Th, reaction of 3U with potassium graphite produces the uranium(III) complex [U(Tren^DPBS)] (5), and 5 can also be prepared by reaction of potassium graphite with 1U. The loss of azide instead of conversion to nitrides contrasts to prior work when the silyl group is iso-propyl silyl, underscoring how ligand substituents profoundly drive the reaction chemistry. Several complexes exhibit T-shaped meta-C−H⋅⋅⋅phenyl and staggered parallel π–π-stacking interactions, demonstrating subtle weak interactions that drive ancillary ligand geometries. Compounds 1An–3An, 4, and 5 have been variously characterised by single crystal X-ray diffraction, multi-nuclear NMR spectroscopy, infrared spectroscopy, UV/Vis/NIR spectroscopy, and elemental analyses.

NIR luminescent materials are widely available for biological applications, and the NIR emitting of Ho³⁺ ions has received widespread attention in the second biological window. The NIR emitting of Ho³⁺ ion sensitized by Mn⁴⁺ has achieved in Ca₁₄Zn₆Ga_9.88O₃₅ : Mn⁴⁺,Ho³⁺ upon UV-vis light excited, and the energy transfer from Mn⁴⁺ to Ho³⁺ ions is mainly dominated by dipole-dipole interaction. The sample displays NIR emitting spectra ranging from 1100 to 1300 nm with two emission centers including Mn⁵⁺ and Ho³⁺ emission, respectively, which holds promising potential for applications in the second biological window.

Abstract

NIR luminescent materials are widely available for biological applications, and the NIR emitting of Ho³⁺ ions has received widespread attention in the second biological window. In this work, Ca₁₄Zn₆Ga₁₀O₃₅ : Mn⁴⁺,Ho³⁺ luminescent materials were synthesized using a high temperature solid state method. Optical properties and energy transfer mechanisms have studied in detail. Upon UV-vis light excitation, the Mn single doped Ca₁₄Zn₆Ga₁₀O₃₅ phosphors exhibit deep red and NIR emission centered at 712 and 1151 nm assigned to Mn⁴⁺ and Mn⁵⁺, respectively. Another stronger NIR emitting peaked at 1195 nm occurs when the Ho³⁺ ion is co-doped into Ca₁₄Zn₆Ga₁₀O₃₅ : Mn⁴⁺. The energy transfer from Mn⁴⁺ to Ho³⁺ ion is performed through a resonant type by a dipole-dipole interaction mechanism. In addition, the thermal stability of Ca₁₄Zn₆Ga₁₀O₃₅ : Mn⁴⁺,Ho³⁺ phosphor has been investigated, and the NIR emission of Ho³⁺ ion maintains more than half the strength at 423 K. The findings indicate that the as-prepared Ca₁₄Zn₆Ga₁₀O₃₅ : Mn⁴⁺,Ho³⁺ luminescent materials hold promise for potential applications in the second biological window.