Synthesis and characterization of three new thermally stable N-heterocyclic germylenes

Three new stable germylenes, rac-1,3-di-tert-butyl-4,5-dimethyl-1,3-diaza-2-germacyclopentane-2-ylide (1), 1,3-di-tert-butyl-4,4-dimethyl-1,3-diaza-2-germacyclopentane-2-ylide (2), and rac-1,3,4-tri-tert-butyl-1,3-diaza-2-germacyclopentane-2-ylide (3) have been synthesized by the reaction of their corresponding germyl dichlorides with elemental lithium. Full synthetic procedures and characterizations are described.     

Facile Access to NaOC≡As and Its Use as an Arsenic Source To Form Germylidenylarsinidene Complexes

A facile, one‐pot synthesis of [Na(OC≡As)(dioxane)_x ] (x =2.3–3.3) in 78 % yield is reported through the reaction of arsine gas with dimethylcarbonate in the presence of NaO^t Bu and 1,4‐dioxane. It has been employed for the synthesis of the first arsaketenyl‐functionalized germylene [LGeAsCO] ( 2 , L=CH[CMeN(Dipp)]₂; Dipp=2,6‐ⁱ Pr₂C₆H₃) from the reaction with LGeCl ( 1 ). Upon exposure to ambient light, 2 undergoes CO elimination to form the 1,3‐digerma‐2,4‐diarsacyclobutadiene [L₂Ge₂As₂] ( 3 ), which contains a symmetric Ge₂As₂ ring with ylide‐like Ge=As bonds. Remarkably, the CO ligand located at the arsenic center of 2 can be exchanged with PPh₃ or an N‐heterocyclic carbene ^{i Pr}NHC donor (^{i Pr}NHC=1,3‐diisopropyl‐4,5‐dimethylimidazol‐2‐ylidene) to afford the novel germylidenylarsinidene complexes [LGe‐AsPPh₃] ( 4 ) and [LGe‐As(^{i Pr}NHC)] ( 5 ), respectively, demonstrating transition‐metal‐like ligand substitution at the arsinidene‐like As atom. The formation of 2 – 5 and their electronic structures have been studied by DFT calculations.     

Cycloadditions of Diarylgermylenes to a Diazabutadiene [1]

The reaction of tetrakis(2‐tert‐butyl‐4,5,6‐trimethylphenyl)digermene, which dissociates into the germylene molecules 2 in solution, with 1,4‐diisopropyl‐1,4‐diazabuta‐1,3‐diene ( 3 ) furnishes the [4+1] cycloaddition product of 2 to the nitrogen atoms of 3 . Under drastic conditions tetrakis(2,4,6‐triisopropylphenyl)digermene also forms the germylene molecules 6 which react with 3 in a similar fashion to afford the corresponding [4+1] cycloadduct.     

The Pyridazine Scaffold as a Building Block for Energetic Materials: Synthesis,Characterization, and Properties

In the present studies, the synthesis of new energetic materials based on the pyridazine scaffold and their characterization is the main subject. For this purpose, desired 3,5‐dimethoxy‐4,6‐dinitropyridazine‐1‐oxide ( 7 ) was synthesized in the first instance. The persubstituted pyridazine precursor laid the groundwork for further preparative modification. The targeted functionalization through the regioselective introduction of various smaller amine nucleophiles such as methylamine or 2‐aminoethanol gave several new energetic materials. Among them are 3,5‐bis(methylamino)‐4,6‐dinitropyridazine‐1‐oxide ( 8 ), 3,5‐bis(methylnitramino)‐4,6‐dinitropyridazine‐1‐oxide ( 9 ), 3,5‐bis(dimethylamino)‐4,6‐dinitropyridazine‐1‐oxide ( 10 ), and 3,5‐bis((2‐hydroxyethyl)amino)‐4,6‐dinitropyridazine‐1‐oxide ( 11 ). With the aim of increasing the detonation performance, compound 8 was additionally nitrated and 3,5‐bis(methylnitramino)‐4,6‐dinitropyridazine‐1‐oxide ( 9 ) was obtained. These new energetic materials were characterized and identified by multinuclear NMR (¹H, ¹³C, ¹⁴N, ¹⁵N) and IR spectroscopy, elemental analysis and mass spectrometry. In addition, their sensitivities toward impact, friction and electrostatic discharge were thoroughly examined. Furthermore, obtained single‐crystals of the substances were characterized by low‐temperature single‐crystal X‐ray diffraction.     

Germabenzenylpotassium: A Germanium Analogue of a Phenyl Anion

Reduction of the stable germabenzene, 1‐Tbt‐2‐tert ‐butyl‐germabenzene (Tbt=2,4,6‐tris[bis(trimethylsilyl)methyl]phenyl), with KC₈ resulted in the formation of 2‐tert ‐butylgermabenzenylpotassium, that is, the germanium analogue of phenylpotassium, under concomitant elimination of the aryl group from the Ge atom. Under an inert atmosphere, this germabenzenylpotassium could be isolated in the form of stable yellow crystals. In the crystalline state, as well as in solution, the germabenzenyl moiety adopts a monomeric form, even though the X‐ray diffraction analysis suggests the presence of highly reactive Ge=C double bonds. The spectroscopic and X‐ray crystallographic analyses, in combination with theoretical calculations indicate an ambident character for this germabenzenyl anion, with contributions from aromatic and germylene resonance structures.     

Photochemical reaction of W(CO)6 with GeCl4 as a source of germyl and germylene compounds acting as initiators for ring-opening metathesis polymerization of norbornene

Photolysis of W(CO)₆ in a solution of n-heptane containing GeCl₄ leads to the formation of two seven-coordinate compounds with direct WGe bonds: [(CO)₄W(μ-Cl)₃W(GeCl₃)(CO)₃] (1) and [(μ-GeCl₂){W(CO)₅}₂] (2). The molecular structures of these two tungsten-germanium compounds have been established by single-crystal X-ray diffraction studies. The germyl compound 1 is a previously synthesized binuclear complex of tungsten(II) with a d⁴ electronic configuration, while in the new germylene compound 2 the tungsten atom is formally in the zero oxidation state with a d⁶ electronic configuration and a direct WW bond. In an attempt to establish whether compounds 1 and 2 could be used as precatalysts for the ring-opening metathesis polymerization (ROMP) of cyclic olefins, their reactivity towards norbornene has been studied. In chloroform-d₁ solution the ROMP reaction is accompanied by the formation of a new olefin, 2,2′-binorbornylidene (bi-(NBE)), as a result of carbene-carbene coupling. In reaction of norbornene carried out in benzene solution the ROMP reaction is accompanied by the formation of 2-phenylnorbornane (hydroarylation product) and small amounts of bi-(NBE). In general, in the presence of olefin, compound 2 undergoes rearrangement to give an olefin compound of the type [(WCO)₅(η²-olefin)].     

A Convenient Synthesis of Azafulleroid of Erythronate as a New Chiral Building Block

Azafulleroid of erythronate 3 as a chiral building block was synthesized conveniently in thermal condition from the reaction of fullerene with azidoerythronate 2.     

High-Performance Quinoline-Malononitrile Core as a Building Block for the Diversity-Oriented Synthesis of AIEgens

In vivo fluorescent monitoring of physiological processes with high-fidelity is essential in disease diagnosis and biological research, but faces extreme challenges due to aggregation-caused quenching (ACQ) and short-wavelength fluorescence. The development of high-performance and long-wavelength aggregation-induced emission (AIE) fluorophores is in high demand for precise optical bioimaging. The chromophore quinoline-malononitrile (QM) has recently emerged as a new class of AIE building block that possesses several notable features, such as red to near-infrared (NIR) emission, high brightness, marked photostability, and good biocompatibility. In this minireview, we summarize some recent advances of our established AIE building block of QM, focusing on the AIE mechanism, regulation of emission wavelength and morphology, the facile scale-up and fast preparation for AIE nanoparticles, as well as potential biomedical imaging applications.     

以苯为模块自组装合成碳纳米片

在300 ℃苯溶剂中, 以无水三氯化铝为催化剂, 以苯和六氯乙烷为碳源, 基于傅克烷基化反应生成三氯乙烯苯, 并以之为模块自组装合成了具有叠层结构的碳微米颗粒, 其层片厚度为300～500 nm. 进而在反应体系和反应条件不变的情况下, 通过引入铝粉颗粒作为基底成功地诱导出厚度为30～50 nm的碳纳米片. 实验结果表明, 所得碳材料由纳米石墨微晶和非晶碳组成. 文中探讨了叠层结构的台阶长大机制, 以及碳纳米片在铝粉表面的异质形核机制.     

Synthesis of an Anti-1,3-Diol Type Chiral Building Block

Duringthelastdecade,1,3-dioltypechiralbuildingbIocksofvariousconfigurationshavebeensynthesizedandappliedwidelyinthetotalsynthesisofnaturalpolyenemacrolideantibiotics1'2andla,25-dihydroxyvitaminD3analogues'.RecentlyWeigandandBrucker4synthesizedachiralbuildingblock(4R,6R)-2,2-dimethyl-5-tert-butyldip4-hydroxymethyl-l,3-dioxane1inlOsteps.Herein,wereportasyntheticrouteofnewbuildingblock(4S,6S)-2,2-dimethyl-5-tert-butyldip2,anenantiomerofl,startingfromreadilyavailableandinexpensiveD( )-xylose3i…     

两亲嵌段共聚物聚乙二醇-聚谷氨酸苄酯纳米粒药物载体的合成研究

用磺酸酯法制备单端氨基聚乙二醇引发剂,引发谷氨酸苄酯羧酸酐开环聚合,生成可生物降解的两亲嵌段共聚物聚乙二醇﹣聚谷氨酸苄酯(PEG-PBLG),用IR,NMR和GPC表征了共聚物。用超微透析法制备PEG-PBLG聚合物纳米粒,荧光芘探针法测定纳米粒的临界聚集浓度(cac)。紫外分光光度计考察纳米粒对疏水性药物的增溶作用,PEG-PBLG可作为亚微粒药物输送系统的载体。     

Tetraphosphanylsilane – A Mild PH2‐Transfer Reagent and Building Block for the Synthesis of a Rhombododecahedral Li6P6Si2‐Cluster Framework

Reaction of the PH₂‐transfer reagent Si(PH₂)₄ ( 1 ) with SiCl₄ affords a mixture of the Cl_nSi(PH₂)_4–n compounds ( 2 a , n = 1), ( 2 b , n = 2), and ( 2 c , n = 3) which were characterized by ¹H‐³¹P‐COSY NMR spectroscopy. The formation of ( 2 a ) is drastically accelerated by using GeCl₄ instead of SiCl₄ as PH₂ acceptor, but a stable molecular GeCl_4–n(PH₂)_n containing product could not be obtained. In contrast, conversion of (C₆F₅)₃GeCl with Si(PH₂)₄ ( 1 ) furnishes 2 a but also the remarkably stable tris(pentafluorophenyl)phosphaneylgermane ( 3 ). The latter is isolated in the form of colorless crystals in 97% yield and represents the first PH₂‐substituted germane being structurally characterized by single‐crystal X‐ray diffraction. Protolysis of 1 with MeOH and PhOH occurs relatively fast and leads to mixtures of compounds of the type (RO)_nSi(PH₂)_4–n ( 4 , n = 1), ( 5 , n = 2), and ( 6 , n = 3). The sterically congested phenols MesOH and 3,5‐Me₂PhOH react with 1 only to the respective mono‐ and disubstituted silylphosphanes ( 4 c , d ) and ( 5 c , d ), respectively; 4 c and 4 d were isolated by fractional condensation in the form of air‐ and moisture‐sensitive oils. Lithiation of 1 with four molar equiv. of LiNiPr₂ in THF/Et₂O at –80 °C, surprisingly, leads to insoluble Si(PHLi)₄ ( 8 a ) which was tetrasilylated with iPr₃SiOSO₂CF₃, affording the tetrakis(triisopropylsilylphosphaneyl)silane ( 8 b ). However, attempts to achieve the tetralithiation of the P atoms in 8 b through reaction with four molar equiv. BuLi leads to the unexpected cluster formation of butyl‐tris[lithium(triisopropylsilyl)phosphanideyl] silane‐dimer ( 9 ) in 30% yield and LiPHSiiPr₃; compound 9 consists of a Li₆P₆Si₂ cluster framework.     

一种含假芪型偶氮生色团两亲性嵌段共聚物的合成与表征

利用原子转移自由基聚合（ATRP）合成了一种新型的含假芪型偶氮生色团的两亲性嵌段共聚物P（HEMA-b-6CNAzo）。首先,采用ATRP引发剂引发三甲基硅保护的羟乙基甲基丙烯酸酯（HEMA—TMS）聚合,得到大分子引发剂P（HEMA—TMS）;接着进一步引发单体甲基丙烯酸6-（N_甲基苯胺基）己酯进行ATRP反应,得...     

Synthesis and Characterization of Heterobimetallic Aluminum‐Germanium(IV) Disulfides

Three heterobimetallic aluminum‐germanium(IV) disulfides are synthesized. The reaction of {LAl[(SLi)₂(THF)₂]}₂ ( 1 ) (L = HC(CMeNAr)₂, Ar = 2,6‐iPr₂C₆H₃) with Ph₂GeCl₂, Me₂GeCl₂, and GeCl₄, respectively, in THF afforded LAl(μ‐S)₂GePh₂ ( 2 ), LAl(μ‐S)₂GeMe₂ ( 3 ) and LAl(μ‐S)₂Ge(μ‐S)₂AlL ( 4 ) in good yields. Compounds 2 , 3 and 4 were investigated by elemental analysis, NMR, EI‐MS and 3 was also characterized by single crystal X‐ray structural analysis.     

Sodium Phosphaethynolate as a Building Block for Heterocycles

Phosphorus‐containing heterocycles have evolved from laboratory curiosities to functional components, such as ligands in catalytically active metal complexes or molecular constituents in electronic devices. The straightforward synthesis of functionalized heterocycles on a larger scale remains a challenge. Herein, we report the use of the phosphaethynolate (OCP)^? anion as a building block for various sterically unprotected and functionalized hydroxy substituted phosphorus heterocycles. Because the resulting heterocycles are themselves anions, they are building blocks in their own right and allow further facile functionalization. This property may be of interest in coordination chemistry and material science.     

Dithiolodithiole as a Building Block for Conjugated Materials

The development of new conjugated organic materials for dyes, sensors, imaging, and flexible light emitting diodes, field‐effect transistors, and photovoltaics has largely relied upon assembling π‐conjugated molecules and polymers from a limited number of building blocks. The use of the dithiolodithiole heterocycle as a conjugated building block for organic materials is described. The resulting materials exhibit complimentary properties to widely used thiophene analogues, such as stronger donor characteristics, high crystallinity, and a decreased HOMO–LUMO gap. The dithiolodithiole (C₄S₄) motif is readily synthetically accessible using catalytic processes, and both the molecular and bulk properties of materials based on this building block can be tuned by judicious choice of substituents.     

Synthesis and Characterization of Ferrocene Derived Cyclic Carbaphosphazenes

Dialkylamino substituted cyclic carbaphosphazenes, (R 2 NCN) 2 (NPCl 2 ) were prepared and reacted with the ferrocene derived hydroxymethyl phosphine sulfide FcCH(CH 3 )P(S)(CH 2 OH) 2 after dilithiation to yield a series of new spirocyclic derivatives of cyclic carbaphosphazenes having ferrocenyl pendant groups. To confirm the formation of six membered spirocycles and to compare their spectral features, transesterification reactions of FcCH(CH 3 )P(S)(CH 2 OH) 2 also were carried out with P(NR 2 ) 3 , yielding the six membered heterocycles FcCH 2 P(S)(CH 2 O) 2 PNR 2 (R = Me, Et). The compounds were characterized by 1 H, 31 P, 13 C NMR, mass spectra, and elemental analysis.