Bis(fluor-diisopropylsilyl)amin als Baustein anorganischer Heterocyclen

Bis(fluoro-diisopropylsilyl)amine as a Building Block for Inorganic Heterocycles Bis(fluoro-diisopropylsilyl)amine I reacts with LiC₄H₉ in a molar ratio 1 : 1 to give the lithium-derivatives II , (iPr₂SiF)₂NLi and with LiOSiMe₃ in a molar ratio 1 : 2 to give the bis(siloxy)amine III , (iPr₂SiOSiMe₃)₂NH. The heterocycles IV : HN(SiiPr₂NPh)₂, V : HN(SiiPr₂O)₂SiiPr₂, VI : HN(SiiPr₂NCH₂)₂, and VII : HN(SiiPr₂OCH₂)₂ are obtained in the reaction of I with dilithiated N,N′-diphenylhydrazine ( IV ), disodiated diisopropylsilanediol (V), dilithiated N,N′-dimethylethylendiamine ( VI ), and disodiated ethylen glycol ( VII ). Treatment of III , IV and V with LiC₄H₉ yields the lithium-derivatives VIII : LiN(SiiPr₂OSiMe₃)₂, IX : LiN(SiiPr₂NPh)₂, and X : LiN(SiiPr₂O)₂SiiPr₂. The reaction of (iPr₂SiFNHSiiPr₂O)₂-1,3-C₆H₄, XI , and the disodium salt of 1,3-propanediol yields the 16-membered heteraphane XII . The crystal structures of VIII and X are reported and discussed.     

修饰NADH模拟物的金属-有机三元环光催化制氢

将含有不同还原型烟酰烟腺嘌呤二核苷酸(NADH)活性中心模拟物的有机配体H2L1和H2L2与钴离子配位自组装获得2例具有氧化还原活性且带有正电荷的金属-有机大环Co-L1和Co-L2.选择阴离子型钌基光敏剂[Ru(dcbpy)3]4-(dcbpy=2,2'-联吡啶-4,4'-二羧酸)作为光敏中心,金属-有机大环结构作为...     

The Fascinating Flexibility and Coordination Modes of a Pentamethylene Connected Macrocyclic CNC Pincer Ligand

The coordination chemistry of an electron-rich macrocyclic CNC pincer-ligand consisting of two pentamethylene tethered N-heterocyclic carbene moieties on a carbazole backbone (bimca^C5) is investigated by mainly NMR spectroscopy and X-ray crystal structure analysis. A bridging coordination mode is found for the lithium complex. With the larger and softer potassium ion, the ligand adopts a facial coordination mode and a polymeric structure by intermolecular potassium nitrogen interactions. The facial coordination is also confirmed at a Cp*Ru fragment, while C-H activation under dehydrogenation at the alkyl chain is observed upon reaction with [Ru(PPh₃)₃Cl₂]. In contrast, Pd(OAc)₂ reacts under C-H activation at the central carbon atom of the pentamethylene tether to an alkyl-pincer macrocycle.     

Active Metal Template Synthesis and Characterization of a Nanohoop [c2]Daisy Chain Rotaxane

Molecules and materials that demonstrate large amplitude responses to minor changes in their local environment play an important role in the development of new forms of nanotechnology. Molecular daisy chains are a type of a mechanically interlocked molecule that are particularly sensitive to such changes in which, in the presence of certain stimuli, the molecular linkage enables muscle-like movement between a reduced-length contracted form and an increased-length expanded form. To date, all reported syntheses of molecular daisy chains are accomplished via passive-template methods, resulting in a majority of structures being switchable only through the addition of an exogenous stimuli such as metal ions or changes in pH. Here, we describe a new approach to these structural motifs that exploits a multi-component active-metal template synthesis to mechanically interlock two pi-rich nanohoop macrocycles into a molecular daisy chain that undergoes large conformational changes using thermal energy.     

Ring Closing Metathesis Using Chiral Template Consisting of Hard and Soft Parts

Summary: Macrocyclic compounds having 18-, 19-, 22-, and 23-membered rings were prepared quantitatively by ring closing metathesis of diene substrates consisting of a rigid o- or m-phthalate group and flexible but geometrically regulated 2,4-pentanediol tethers. From the p-phthalate analogues, the ring closing metathesis and the cyclic dimmer formation were observed to give 24-membered ring (70% yield) and 40-membered ring (65% yield) respectively.     

Preparation,characterization and catalytic application of PdPt bimetallic nanoparticles stabilized by 15‐membered triolefinic macrocycle‐terminated poly(propylene imine) dendrimer

PdPt bimetallic nanoparticles stabilized by 15‐membered triolefinic macrocycle‐stabilized poly(propylene imine) dendrimer (G3‐M(Pd_x Pt_10−x ) DSNs) have been prepared via synthesis of a 15‐membered triolefinic macrocycle‐modified third‐generation poly(propylene imine) dendrimer (G3‐M) and then synchronous ligand exchange with Pd(PPh₃)₄/Pt(PPh₃)₄ complexes. The structure and catalytic activity of the DSNs were characterized using Fourier transform infrared, ¹H NMR, transmission electron microscopy, energy‐dispersive X‐ray and X‐ray photoelectron analyses. As a novel catalyst system, it can be concluded that the composition of the bimetallic nanoparticles has an influence on the catalytic activity of the hydrogenation reaction of acrylonitrile–butadiene rubber, which can be related to synergistic effect. Furthermore, the selectivity and recyclability of G3‐M(Pd_x Pt_10−x ) DSN catalyst are also discussed.     

An 18-member dinucleating unsymmetrical [N10] macrocycle and its bimetallic complexes M2LCl2(ClO4) (M=Co,Ni, Cu,Zn, Cd or Hg)

The 18-member unsymmetrical dinucleating Shiff-base decaaza [N₁₀] macrocyclic ligand, 2,8,11,17-tetramethyl-3,5,7,12,14,16-hexaphenyl-[1,3,5,7,9,10,12,14,16,18] decaazaoctadeca-2,8,11,17-tetraene dihydroperchlorate (L · 2HClO₄) was obtained as a cream colored solid from reaction of N-acetylaniline and hydrazine in the presence of HClO₄ followed by cyclization (capping) using aniline and excess HCHO in methanol at RT. Reactions of L · 2HClO₄ with MCl₂ and [M(Ph₃P)₂Cl₂] afforded air stable complexes, M₂LCl₄(ClO₄)₂ (M = Co, Ni, Cu, Zn or Cd). The compounds have been characterized by physico-chemical and spectroscopic studies. FAB–Mass spectral data support bimetallic coordination by the macrocycle. IR studies confirm coordination/encapsulation of metal ions involving unsymmetrical aza sites. Magnetic susceptibility and UV–Visible data indicate a low-spin, five-coordinate geometry for Co(II) and Ni(II) complexes. The anisotropic EPR signals (g _∥ > g _⊥) for Cu²⁺ complex suggest an axial type tetragonality. Molecular model computations have been employed for a theoretical perspective of the ligand and complexes. The important bond lengths and bond angles have been estimated using CS Chem-3D software. The ionic association constant (K ₁) and thermodynamic free energy change (ΔG) were evaluated from the conductometric data of the complexes, which indicate presence of a strong ion-pair even in solution. Cyclic voltametric studies on solutions of M₂LCl₄(ClO₄)₂ (M = Co, Ni or Cu) in DMSO indicate reversible and quasi-reversible redox couples.     

Ferrocene- and Biferrocene-Containing Macrocycles towards Single-Molecule Electronics

Cyclic multiredox centered systems are currently of great interest, with new compounds being reported and developments made in understanding their behavior. Efficient, elegant, and high-yielding (for macrocyclic species) synthetic routes to two novel alkynyl-conjugated multiple ferrocene- and biferrocene-containing cyclic compounds are presented. The electronic interactions between the individual ferrocene units have been investigated through electrochemistry, spectroelectrochemistry, density functional theory (DFT), and crystallography to understand the effect of cyclization on the electronic properties and structure.     

New Wine in Old Bottles: Prolonging Room‐Temperature Phosphorescence of Crown Ethers by Supramolecular Interactions

Supramolecular macrocyclic hosts have long been used in smart materials. However, their triplet emission and regulation at crystal level is rarely studied. Herein, ultralong and universal room‐temperature phosphorescence (RTP) is reported for traditional crown ethers. A supramolecular strategy involving chain length adjustment and morphological locking through complexation with K⁺ was explored as a general method to tune the phosphorescence lifetime in the solid state. A maximum 10‐fold increase of lifetime after complex formation accompanied with by invisible to visible phosphorescence was achieved. A deep encryption based on this activated RTP strategy was also facilely fabricated. This work thus opens a new world for supramolecular macrocycles and their intrinsic guest responsiveness offers a new avenue for versatile smart luminescent materials.