Facile Preparation of WO3−x Dots with Remarkably Low Toxicity and Uncompromised Activity as Co-reactants for Clinical Diagnosis by Electrochemiluminescence

The exceptional nature of WO_3−x dots has inspired widespread interest, but it is still a significant challenge to synthesize high-quality WO_3−x dots without using unstable reactants, expensive equipment, and complex synthetic processes. Herein, the synthesis of ligand-free WO_3−x dots is reported that are highly dispersible and rich in oxygen vacancies by a simple but straightforward exfoliation of bulk WS₂ and a mild follow-up chemical conversion. Surprisingly, the WO_3−x dots emerged as co-reactants for the electrochemiluminescence (ECL) of Ru(bpy)₃²⁺ with a comparable ECL efficiency to the well-known Ru(bpy)₃²⁺/tripropylamine (TPrA) system. Moreover, compared to TPrA, whose toxicity remains a critical issue of concern, the WO_3−x dots were ca. 300-fold less toxic. The potency of WO_3−x dots was further explored in the detection of circulating tumor cells (CTCs) with the most competitive limit of detection so far.     

碳酸氢钠活化过氧化氢对烯烃的环氧化

研究了碳酸氢钠活化H<,2>O<,2>(BAP)体系对苯乙烯和不饱和脂肪酸甲酯的环氧化.分别考察了碳酸氢钠、表面活性剂、加料方式、反应时间、H<,2>O<,2>用量和反应温度对BAP体系H<,2>O<,2>分解和烯烃环氧化的影响.在n(苯乙烯):n(H<,2>O<,2>):n(NaHCO<,3>)=1:10:0.25,...     

The Ketimide Ligand is Not Just an Inert Spectator: Heteroallene Insertion Reactivity of an Actinide–Ketimide Linkage in a Thorium Carbene Amide Ketimide Complex

The ketimide anion R₂C?N^? is an important class of chemically robust ligand that binds strongly to metal ions and is considered ideal for supporting reactive metal fragments due to its inert spectator nature; this contrasts with R₂N^? amides that exhibit a wide range of reactivities. Here, we report the synthesis and characterization of a rare example of an actinide ketimide complex [Th(BIPM^TMS){N(SiMe₃)₂}(N?CPh₂)] [ 2 , BIPM^TMS=C(PPh₂NSiMe₃)₂]. Complex 2 contains Th?C_carbene, Th? N_amide and Th? N_ketimide linkages, thereby presenting the opportunity to probe the preferential reactivity of these linkages. Importantly, reactivity studies of 2 with unsaturated substrates shows that insertion reactions occur preferentially at the Th? N_ketimide bond rather than at the Th?C_carbene or Th? N_amide bonds. This overturns the established view that metal‐ketimide linkages are purely inert spectators.     

Effects of a chemically modified multiwall carbon nanotubes on electro-optical properties of PDLC films

Polymer dispersed liquid crystal (PDLC) films are fabricated by well-known polymerization-induced phase separation method. In this paper, the dispersion of multi-walled carbon nanotubes (MWCNT) in liquid crystals has been enhanced by chemical modification and we have investigated their effects on the morphology, electro-optical properties and conductivity of the PDLC films. Results indicated that the threshold voltage and the saturation voltage of PDLC films decreased with the increase of the doping concentration of MWCNT or chemically modified MWCNT, because carbon nanotubes can enhance the electric field by reducing the resistivity of the medium and increasing the capacitance of the cells. It can be viewed obviously that the contrast ratio of the PDLC films doped with the chemically modified MWCNT is higher than that of the MWCNT.     

Silyl‐Phosphino‐Carbene Complexes of Uranium(IV)

Unprecedented silyl‐phosphino‐carbene complexes of uranium(IV) are presented, where before all covalent actinide–carbon double bonds were stabilised by phosphorus(V) substituents or restricted to matrix isolation experiments. Conversion of [U(BIPM^TMS)(Cl)(μ‐Cl)₂Li(THF)₂] ( 1 , BIPM^TMS=C(PPh₂NSiMe₃)₂) into [U(BIPM^TMS)(Cl){CH(Ph)(SiMe₃)}] ( 2 ), and addition of [Li{CH(SiMe₃)(PPh₂)}(THF)]/Me₂NCH₂CH₂NMe₂ (TMEDA) gave [U{C(SiMe₃)(PPh₂)}(BIPM^TMS)(μ‐Cl)Li(TMEDA)(μ‐TMEDA)_0.5]₂ ( 3 ) by α‐hydrogen abstraction. Addition of 2,2,2‐cryptand or two equivalents of 4‐N,N‐dimethylaminopyridine (DMAP) to 3 gave [U{C(SiMe₃)(PPh₂)}(BIPM^TMS)(Cl)][Li(2,2,2‐cryptand)] ( 4 ) or [U{C(SiMe₃)(PPh₂)}(BIPM^TMS)(DMAP)₂] ( 5 ). The characterisation data for 3 – 5 suggest that whilst there is evidence for 3‐centre P?C?U π‐bonding character, the U=C double bond component is dominant in each case. These U=C bonds are the closest to a true uranium alkylidene yet outside of matrix isolation experiments.     

Heck reactions of stilbenoid chromophores with alkoxysilyl-substituted styrenes: Synthesis of monomers for luminescent polymers

Luminescent stilbenoid chromophores with diethoxysilane end groups are prepared via Heck reactions. Diethoxysilane-substituted styrenes are used as vinylic components, thus allowing the combined connection of the chromophore to the silane moiety with an extension of the π-system. Monodisperse oligo(phenylenevinylene)s of different conjugation lengths and bromine or iodine as reactive sites are used as coupling partners. Electrical and optical properties are tuned via the length of the conjugated system, electron withdrawing cyanide and electron donating alkoxy side chains, the latter guarantee high solubility of the final compounds.Dedicated to Prof. Dr. H. Ringsdorf on the occasion of his 75th birthday     

Photolytic and Reductive Activations of 2-Arsaethynolate in a Uranium–Triamidoamine Complex: Decarbonylative Arsenic-Group Transfer Reactions and Trapping of a Highly Bent and Reduced Form

Little is known about the chemistry of the 2-arsaethynolate anion, but to date it has exclusively undergone fragmentation reactions when reduced. Herein, we report the synthesis of [U(Tren^TIPS)(OCAs)] ( 2 , Tren^TIPS=N(CH₂CH₂NSiiPr₃)₃), which is the first isolable actinide-2-arsaethynolate linkage. UV-photolysis of 2 results in decarbonylation, but the putative [U(Tren^TIPS)(As)] product was not isolated and instead only [{U(Tren^TIPS)}₂(μ-η²:η²-As₂H₂)] ( 3 ) was formed. In contrast, reduction of 2 with [U(Tren^TIPS)] gave the mixed-valence arsenido [{U(Tren^TIPS)}₂(μ-As)] ( 4 ) in very low yield. Complex 4 is unstable which precluded full characterisation, but these photolytic and reductive reactions testify to the tendency of 2-arsaethynolate to fragment with CO release and As transfer. However, addition of 2 to an electride mixture of potassium-graphite and 2,2,2-cryptand gives [{U(Tren^TIPS)}₂{μ-η²(OAs):η²(CAs)-OCAs}][K(2,2,2-cryptand)] ( 5 ). The coordination mode of the trapped 2-arsaethynolate in 5 is unique, and derives from a new highly reduced and bent form of this ligand with the most acute O-C-As angle in any complex to date (O-C-As ≈128°). The trapping rather than fragmentation of this highly reduced O-C-As unit is unprecedented, and quantum chemical calculations reveal that reduction confers donor–acceptor character to the O-C-As unit.     

Uranium Metalla‐Allenes with Carbene Imido R2C=UIV=NR′ Units (R=Ph2PNSiMe3; R′=CPh3): Alkali‐Metal‐Mediated Push–Pull Effects with an Amido Auxiliary

We report uranium(IV)‐carbene‐imido‐amide metalla‐allene complexes [U(BIPM^TMS)(NCPh₃)(NHCPh₃)(M)] (BIPM^TMS=C(PPh₂NSiMe₃)₂; M=Li or K) that can be described as R₂C=U=NR′ push–pull metalla‐allene units, as organometallic counterparts of the well‐known push–pull organic allenes. The solid‐state structures reveal that the R₂C=U=NR′ units adopt highly unusual cis‐arrangements, which are also reproduced by gas‐phase theoretical studies conducted without the alkali metals to remove their potential structure‐directing roles. Computational studies confirm the double‐bond nature of the U=NR′ and U=CR₂ interactions, the latter increasingly attenuated by potassium then lithium when compared to the hypothetical alkali‐metal‐free anion. Combined experimental and theoretical data show that the push–pull effect induced by the alkali metal cations and amide auxiliary gives a fundamental and tunable structural influence over the C=U^IV=N units.