Tight Xenon Confinement in a Crystalline Sandwich‐like Hydrogen‐Bonded Dimeric Capsule of a Cyclic Peptide

A cyclic hexapeptide with three pyridyl moieties connected to its backbone forms a hydrogen‐bonded dimer, which tightly encapsulates a single xenon atom, like a pearl in its shell. The dimer imprints its shape and symmetry to the captured xenon atom, as demonstrated by ¹²⁹Xe NMR spectroscopy, single‐crystal X‐ray diffraction, and computational studies. The dimers self‐assemble hierarchically into tubular structures to form a porous supramolecular architecture, whose cavities are filled by small molecules and gases.     

Metal‐Ion‐Binding Analogs of Ribonucleosides: Preparation and Formation of Ternary Pd2+ and Hg2+ Complexes with Natural Pyrimidine Nucleosides

Four metal‐ion‐binding nucleosides, viz. 2,6‐bis(1‐methylhydrazinyl)‐9‐(β‐D ‐ribofuranosyl)‐9H‐purine ( 2a ) and its N‐acetylated derivative, 2b , 2,4‐bis(3,5‐dimethyl‐1H‐pyrazol‐1‐yl)‐5‐(β‐D ‐ribofuranosyl)pyrimidine ( 3 ), and 2,4‐bis(1‐methylhydrazinyl)‐5‐(β‐D ‐ribofuranosyl)pyrimidine ( 4 ) have been synthesized. The ability of these nucleosides and the previously prepared 2,6‐bis(3,5‐dimethyl‐1H‐pyrazol‐1‐yl)‐9‐(β‐D ‐ribofuranosyl)‐9H‐purine to form Pd²⁺‐ and Hg²⁺‐mediated complexes with uridine has been studied by ¹H‐NMR spectroscopy. To obtain additional support for the interpretation of the NMR data, comparative measurements on the ternary‐complex formation between pyridine‐2,6‐dicarboxamide ( 5 ), pyrimidine nucleosides, and K₂PdCl₄ were carried out.     

Experimental and Theoretical Studies on Arene‐Bridged Metal–Metal‐Bonded Dimolybdenum Complexes

The bis(hydride) dimolybdenum complex, [Mo₂(H)₂{HC(N‐2,6‐iPr₂C₆H₃)₂}₂(thf)₂], 2 , which possesses a quadruply bonded Mo₂^II core, undergoes light‐induced (365 nm) reductive elimination of H₂ and arene coordination in benzene and toluene solutions, with formation of the Mo^I₂ complexes [Mo₂{HC(N‐2,6‐iPr₂C₆H₃)₂}₂(arene)], 3?C₆H₆ and 3?C₆H₅Me , respectively. The analogous C₆H₅OMe, p‐C₆H₄Me₂, C₆H₅F, and p‐C₆H₄F₂ derivatives have also been prepared by thermal or photochemical methods, which nevertheless employ different Mo₂ complex precursors. X‐ray crystallography and solution NMR studies demonstrate that the molecule of the arene bridges the molybdenum atoms of the Mo^I₂ core, coordinating to each in an η² fashion. In solution, the arene rotates fast on the NMR timescale around the Mo₂‐arene axis. For the substituted aromatic hydrocarbons, the NMR data are consistent with the existence of a major rotamer in which the metal atoms are coordinated to the more electron‐rich C?C bonds.     

Metal‐Assisted One‐Pot Synthesis of Isoporphyrin Complexes

Zinc and cadmium complexes of meso‐arylisoporphyrins carrying a pyrrolyl or dipyrrinyl substituent at the sp³ carbon atom were obtained through a simple one‐pot variation of the Alder–Longo porphyrin synthesis. Key to the formation and stabilization of isoporphyrins is the presence of metal acetates during the oxidative macrocyclization step. The characteristic Q‐bands of isoporphyrins are found in the NIR region between 750 nm and 880 nm. All of the isolated pyrrolyl‐ and dipyrrinyl‐appended isoporphyrins are stable under typical laboratory conditions and allow chemical transformations like BF₂ coordination, transmetalation, and ligand exchange.     

532 nm纳秒激光电离产生Xez＋(z ≤ 11)高价离子

利用25 ns脉冲Nd-YAG 532 nm激光,在1011 W•cm－2的光场强度下,研究了Xe原子团簇的激光电离过程,观察到较强的高价离子信号,其中最高价态达＋11.不同脉冲束位置和束源压力的实验表明,仅当激光作用于脉冲束中段时才能观察到高价离子,且高价离子信号强度随束源压力的增加而迅速增强,说明束中大尺寸团簇的存在与高价离子的形成密切相关.通过实验,认为高价离子可能来源于电离原子团簇而形成的纳米尺度等离子体小球对激光光场的共振吸收.     

Novel Metal‐Polyurethane Complexes with Enhanced Antimicrobial Activity

Summary: The silver coating of polymers has been intensively investigated in the last few decades as an effective non‐resistance‐inducing strategy to prevent medical device‐related infections. We have developed a completely new approach to incorporate silver ions in polymers by the synthesis of a carboxylated polyurethane able to coordinate Ag⁺. The obtained polymers possess mechanical properties suitable for the development of medical devices, without any risk of loss of activity. To minimize the risk of increasing antibiotic resistance, the metal ion‐containing polymers are loaded with ciprofloxacin, which possesses a different mechanism of antimicrobial action, thus a system able to inhibit Staphylococcus epidermidis and Pseudomonas aeruginosa growth for at least one month is developed.

SEM images showing a mature S. epidermidis biofilm on the surface of the carboxylated polyurethane (left) and the surface of the silver ion‐containing polyurethane free from bacterial colonization (right) after 48 h of incubation.     

Chelate Complexes of the Pyrid‐2‐yl Analogue of Tetracyclone

The tetradentate ligand 2,3,4,5‐tetra(pyrid‐2‐yl)cyclopent‐2,4‐dien‐1‐one ( 3 ) was prepared and used for the synthesis of the dinuclear chelates [μ‐( 3 )(MX₂)₂] (MX₂ = BeCl₂, ZnCl₂, ZnBr₂, HgCl₂, HgBr₂); the closely related BeCl₂ chelate of the bidentate ligand 2,5‐diphenyl‐3,4‐di(pyrid‐2‐yl)cyclopent‐2,4‐dien‐1‐one ( 1 ) was also prepared. The structures of these compounds were determined by X‐ray crystallography and compared to those of the corresponding unchelated analogues [(py)₂MX₂] (py = pyridine). Aggregation to polymeric chains by chloro‐bridging was observed for [μ‐( 3 )(HgCl₂)₂] in the crystal.     

The Reaction of 2‐X‐1, 2‐Difluoroalk‐1‐enyldifluoroboranes with Xenon Difluoride. A Methodical Approach to 1, 2‐Difluoroalk‐1‐enylxenon(II) Salts

2‐X‐1, 2‐Difluoroalk‐1‐enylxenon(II) salts were prepared by the reaction of XeF₂ with XCF=CFBF₂ (X = F, trans‐H, cis‐Cl, trans‐Cl, cis‐CF₃, cis‐C₂F₅) but no organoxenon(II) compounds were obtained when the trans‐isomers of boranes, trans‐XCF=CFBF₂ (X = CF₃, C₄F₉, C₄H₉, Et₃Si), were used under similar conditions.     

The Stereospecific Substitution of the Xenon Atom in cis‐Perfluoroalk‐1‐enylxenon(II) Salts by Hydrogen,Halogens, and the Phenyl Group

The substitution of the xenon atom in reactions of [cis‐C_nF_2n+1CF=CFXe][Y] salts with benzene, iodide, and bromide anions in propionitrile solution by the phenyl group, or iodine, and bromine atoms, respectively, occurred stereospecifically. When a propionitrile solution of [cis‐C₂F₅CF=CFXe][AsF₆] was kept at —40 °C without an additional reactant, the fluoroalkene cis‐C₂F₅CF=CFH was the only isomer obtained.     

Reversible Encapsulation of Xenon and CH2Cl2 in a Solid‐State Molecular Organometallic Framework (Guest@SMOM)

Reversible encapsulation of CH₂Cl₂ or Xe in a non‐porous solid‐state molecular organometallic framework of [Rh(Cy₂PCH₂PCy₂)(NBD)][BAr^F₄] occurs in single‐crystal to single‐crystal transformations. These processes are probed by solid‐state NMR spectroscopy, including ¹²⁹Xe SSNMR. Non‐covalent interactions with the ‐CF₃ groups, and hydrophobic channels formed, of [BAr^F₄]^? anions are shown to be important, and thus have similarity to the transport of substrates and products to and from the active site in metalloenzymes.     

First‐Row Transition‐Metal–Diborane and –Borylene Complexes

A combined experimental and quantum chemical study of Group 7 borane, trimetallic triply bridged borylene and boride complexes has been undertaken. Treatment of [{Cp*CoCl}₂] (Cp*=1,2,3,4,5‐pentamethylcyclopentadienyl) with LiBH₄ ? thf at ?78 °C, followed by room‐temperature reaction with three equivalents of [Mn₂(CO)₁₀] yielded a manganese hexahydridodiborate compound [{(OC)₄Mn}(η⁶‐B₂H₆){Mn(CO)₃}₂(μ‐H)] ( 1 ) and a triply bridged borylene complex [(μ₃‐BH)(Cp*Co)₂(μ‐CO)(μ‐H)₂MnH(CO)₃] ( 2 ). In a similar fashion, [Re₂(CO)₁₀] generated [(μ₃‐BH)(Cp*Co)₂(μ‐CO)(μ‐H)₂ReH(CO)₃] ( 3 ) and [(μ₃‐BH)(Cp*Co)₂(μ‐CO)₂(μ‐H)Co(CO)₃] ( 4 ) in modest yields. In contrast, [Ru₃(CO)₁₂] under similar reaction conditions yielded a heterometallic semi‐interstitial boride cluster [(Cp*Co)(μ‐H)₃Ru₃(CO)₉B] ( 5 ). The solid‐state X‐ray structure of compound 1 shows a significantly shorter boron–boron bond length. The detailed spectroscopic data of 1 and the unusual structural and bonding features have been described. All the complexes have been characterized by using ¹H, ¹¹B, ¹³C NMR spectroscopy, mass spectrometry, and X‐ray diffraction analysis. The DFT computations were used to shed light on the bonding and electronic structures of these new compounds. The study reveals a dominant B?H?Mn, a weak B?B?Mn interaction, and an enhanced B?B bonding in 1 .