Transmetalation Research Articles

Preparation and structural characterization of 4-pyridylboron-capped iron(II) clathrochelates and their chemical transformations into hybrid metallo(IV)-phthalocyaninatoclathrochelate derivatives

Mixed boron,antimony-capped iron(II) tris-dioximate monoclathrochelates and their hybrid phthalocyaninatoclathrochelate derivatives, the molecules of which are decorated with the single N-donor 4-pyridyl group, were obtained using two different approaches, such as (i) a transmetallation (a capping group exchange) reaction of their antimony-capped macrobicyclic precursors, and (ii) the direct template condensation of the [Formula: see text] ion as a matrix. The obtained complexes were characterized using elemental analysis, 1H and [Formula: see text]C{1H} NMR, MALDI-TOF MS, and UV–vis spectra, and by the single-crystal X-ray diffraction experiments. Solution UV-vis spectra of 4-pyridyl-terminated iron(II) phthalocyaninatoclathrochelates can be described as a superposition of the spectrum of its metallocomplex precursor MIVPc and that of the iron(II)-encapsulating semiclathrochelate fragment. As follows from the X-ray diffraction data for the hybrid hafnium(IV)-capped tris-dimethylglyoximate pthalocyaninatoclathrochelate and its macrobicyclic boron,antimony-capped precursor, their [Formula: see text]-coordination polyhedra possess the geometry close to intermediate between a trigonal prism (TP) and a trigonal antiprism with the distortion angles [Formula: see text] of 20–30∘. Due to a non-equivalence of their capping fragments, it can be also described as a distorted truncated trigonal pyramid. [Formula: see text]-coordination polyhedron in the hybrid complex possesses the geometry of a capped TP. 4-Pyridylboron-capped pthalocyaninatoclathrochelates are proposed as prospective monodentate N-donor 3D-ligands for the design of various clathrochelate-based coordination assemblies, polytopic and polynuclear systems.

A photoluminescent and electrochemiluminescent probe based on an iridium(III) complex with a boronic acid-functionalised ancillary ligand for the selective detection of mercury(II) ions.

Exposure to mercury(II) ions (Hg2+) can cause various diseases such as Minamata disease, acrodynia, Alzheimer's disease, and Hunter-Russell syndrome, and even organ damage. Therefore, real-time and accurate monitoring of Hg2+ in environmental samples is crucial. In this study, we report a photoluminescent (PL) and electrochemiluminescent (ECL) probe based on a cyclometalated Ir(III) complex for the selective detection of Hg2+. The introduction of a reaction site, o-aminomethylphenylboronic acid, on the ancillary ligands allowed a prompt transmetalation reaction to take place between Hg2+ and boronic acid. This reaction resulted in significant decreases of the PL and ECL signals due to the photo-induced electron transfer from the Ir(III) complex to the Hg2+ ions. The probe was applied to the selective detection of Hg2+, and the signal changes revealed a linear correlation with Hg2+ concentrations in the range of 0-10 μM (LOD = 0.72 μM for PL, 8.03 nM for ECL). The designed probe allowed the successful quantification of Hg2+ in tap water samples, which proves its potential for the selective detection of Hg2+ in environmental samples.

Synthesis of AgI and AuI Complexes from Tetra(thiophene‐NHC)‐Substituted Ethylene and Their Tunable Fluorescence Properties

AbstractDinuclear silver(I) and gold(I) complexes have been prepared from (NHC‐thiophene)‐substituted ethylene (NHC = N‐heterocyclic carbene). Both the 1,2,3,4‐tetrathienylethene (TTE)‐bridged tetrakisazolium salts (H4‐L1(PF6)4 and H4‐L2(PF6)4) and the 2,2′‐(diphenylethene‐1,1‐diyl)dithiophene (DPDT)‐bridged bisimidazolium ligand precursors H4‐L3(PF6)2 have been prepared and are treated with Ag2O to give dinuclear tetracarbene complexes [Ag2L](PF6)2 (L = L1, L2) and [Ag2(L3)2](PF6)2, respectively. The silver(I) complexes undergo a transmetalation reaction with [AuCl(THT)] (THT = tetrahydrothiophene) to furnish gold(I) NHC complexes with retention of the original structures. All complexes have been characterized by multi‐nuclear magnetic resonance (NMR) and high‐resolution electrospray ionization (HR‐ESI) mass spectrometry, and single‐crystal X‐ray diffraction analysis. The thiophene‐containing NHC complexes exhibit aggregation‐induced emission behavior in acetonitrile/water solutions and temperature‐dependent fluorescence properties.

Silyl-functionalised silver rhodium and iridium N-heterocyclic carbene complexes with promising cytotoxicity and antimicrobial potential

In the present study, we have synthesized Ag, Rh, and Ir complexes of a silyl-substituted NHC ligand in order to investigate their biological properties. Firstly, Ag-NHC ( 2 ) complex was synthesized by the interaction of Ag 2 O with benzimidazolium iodide ( 1 ). Rh- ( 3 ) and Ir-NHC ( 4 ) complexes were synthesized by the transmetalation reaction between Ag-NHC and [M(cod)Cl] 2 (M = Rh or Ir) dimers. The complexes were characterised by NMR spectroscopy and elemental analyses, and crystal structures of Rh- and Ir-NHC ( 3 and 4 ) were also reported. The cytotoxic effects of the complexes were tested on four human cancer cell lines and the antimicrobial activities of the complexes were tested against a panel of nine pathogenic microorganisms. The complexes performed comparable or better activity than standards, cisplatin and AgNO 3 .

Synthesis and Investigation of Antimicrobial, Antioxidant, Enzymatic Inhibitory, and Antiproliferative Activities of Ruthenium (II) Complexes Bearing Benzimidazole-Based N-Heterocyclic Carbene (NHC) Ligands

The benzimidazolium salts 2a-d were synthesized by quaternization of 1-(4-tet-buthylbenzyl) benzimidazole, with the corresponding benzysl bromide. The reactions were carried out in dimethylformamide at 70 °C for 48 h. Therefore, Ag2O and benzimidazolium salts 2a-d were reacted in dichloromethane at room temperature under dark and Ag(I)-NHC complex 3 was obtained in very good yields. The Ru(II)-NHC complexes (4a-d) were synthesized via transmetalation reaction from 3a-d. The structures of the obtained compounds were characterized by different spectroscopic techniques such as 1H and 13C NMR, elemental analysis, and melting point detection. The lowest MICs values were obtained with the two complexes 4b and 4d. Enzymatic inhibitory investigation against acetylcholinesterase (AChE) and tyrosinase (TyrE), showed that the two complexes 4b and 4d are the most potent inhibitors against (AchE) with an IC50 of 2.52 and 5.06 µg mL–1 respectively, and against (TyrE) with an IC50 of 19.88 and 24.95 µg mL–1 respectively. Screening of the selected N-Heterocyclic carbene (NHC) ligands (2a-2d) and their respective ruthenium (II) complexes (4a-4d) against colon carcinoma cells lines (HCT-116) and hepatocellular carcinoma cells lines (HepG-2). Furthermore, compounds 2c, 2d, 4b were showed weak cytotoxic action with IC50 ranging from 13.38 to 18.33 µg in human colon carcinoma cancer cell lines and from 14.36 to 18.45 µg in hepatocellular carcinoma cells lines.

UV-light-driven conversion of gadoterate meglumine: Insight into the photocatalyst's influence on conversion pathway, transformation products, and release of toxic ionic gadolinium

Dotarem is the most used gadolinium-based contrast agent and one of the main sources of anthropogenic gadolinium in water systems. A Dotarem aqueous solution at its excretion level concentration was photocatalyzed by different materials. A 42% conversion was reached by photolysis, followed by photocatalysis with TiO2, iron oxides, and TiO2/γ-Fe2O3 (39–29%). Transformation products were identified to correspond to hydroxylated-Dotarem derivatives, Gd-free compounds, and Fe-complexes. A conversion pathway was proposed to demonstrate that, under UVC irradiation, Dotarem released toxic Gd3+, and in the presence of Fe-containing materials, transmetallation reactions occurred between the Gd3+ and Fe3+ ions.

Tridentate NacNac Stabilized Tin and Nickel Complexes: Access to a Monomeric Nickel Hydride and Its Catalytic Application.

The transmetalation reaction of picolyl-supported tridentate nacnac germylene monochloride [2,6-iPr2-C6H3NC(Me)CHC(Me)NH(CH2py)]GeCl (1) (py = pyridine) with SnCl2 results in an analogous stannylene chloride (2). The three-coordinated stannylenium cation [{2,6-iPr2-C6H3NC(Me)CHC(Me)NH(CH2py)}Sn]+ with SnCl3- as a counteranion (3) has been generated through the abstraction of chloride ligand from 2 using an additional equivalent of SnCl2. Instead of forming a donor-acceptor complex, 2 undergoes a facile redox transmetalation reaction with Ni(COD)2 (COD = cyclooctadiene) and CuCl to afford analogous nickel and copper complexes [2,6-iPr2-C6H3NC(Me)CHC(Me)NH(CH2py)]MCl [M = Ni (4) and Cu (5)]. The reactions of 4 with potassium tri-sec-butylborohydride (commonly known as K-selectride) and AgSbF6 provide access to monomeric Ni(II) hydride, [2,6-iPr2-C6H3NC(Me)CHC(Me)NH(CH2py)]NiH (6) and a Ni(II) cation, [{2,6-iPr2-C6H3NC(Me)CHC(Me)NH(CH2py)}Ni][SbF6] (7), respectively. 6 was found to be an effective catalyst for the hydroboration of amides.

Zinc– and Copper–Salicyaldimine complexes: Simultaneous observation of both metal–ligand coordination and weak CH⋯N contact about a single N-donor and the transmetallation reactions

Two salicyaldimine ligands, HsalCl-3-py and HsalOMe-3-py, functionalized with the pyridyl group on the imine side and their Zn and Cu complexes with a general formula [ML2], where M ​= ​Zn, L ​= ​salCl-3-py (1), salOMe-3-py (2); M ​= ​Cu, L ​= ​salCl-3-py (3), salOMe-3-py (4), have been synthesized and characterized by nuclear magnetic resonance (NMR) spectroscopy, mass spectroscopy (MS), infrared (IR) spectroscopy, elemental analysis (EA), scanning electron microscope (SEM) and further by single-crystal X-ray diffraction analysis and X-ray powder diffraction (XRPD). The crystal structures of Zn– and Cu–salicyaldimine complexes exhibited that the M(II) center is coordinated by two N,O-chelated salicyaldimine ligands in a square-planar geometry, and two further pyridyl donating groups from two neighboring molecules at the axial positions, resulted in self-aggregation to form a two-dimensional (4,4)-sheet. Interestingly, apart from the strong M–N(pyridyl) coordination bond, the weak CH⋯N(pyridyl) hydrogen bonding interactions are simultaneously formed between the pyridyl N-donor and one pyridyl hydrogen of the equatorial salicyaldimine ligand. The electronic absorption spectra of the Zn– and Cu–salicyaldimine complexes in methanol solutions showed the appearance of a metal-to-ligand charge transfer absorption other than the intraligand charge transfer transitions after the complexation of azomethine (–CN–) with M(II) center. On the other hand, salicyaldimine ligands and Cu–salicyaldimine complexes showed no or weak fluorescence emissions. By contrast, Zn–salicyaldimine complexes emitted intense cyan and green light fluorescence in both solid-state and methanol solutions. Noteworthy, transmetallation of Zn–salicyaldimine complexes with Cu2+ ions would be achieved, producing corresponding Cu–salicyaldimine complexes. This implies the stronger binding ability of Cu2+ than that of Zn2+ to salicyaldimine ligands.

Stereoretentive cross-coupling of chiral amino acid chlorides and hydrocarbons through mechanistically controlled Ni/Ir photoredox catalysis

The direct modification of naturally occurring chiral amino acids to their amino ketone analogs is a significant synthetic challenge. Here, an efficient and robust cross-coupling reaction between chiral amino acid chlorides and unactivated C(sp3)–H hydrocarbons is achieved by a mechanistically designed Ni/Ir photoredox catalysis. This reaction, which proceeds under mild conditions, enables modular access to a wide variety of chiral amino ketones that retain the stereochemistry of the starting amino acids. In-depth mechanistic analysis reveals that the strategic generation of an N-acyllutidinium intermediate is critical for the success of this reaction. The barrierless reduction of the N-acyllutidinium intermediate facilitates the delivery of chiral amino ketones with retention of stereochemistry. This pathway avoids the formation of a detrimental nickel intermediate, which could be responsible for undesirable decarbonylation and transmetalation reactions that limit the utility of previously reported methods.

Unexpected C−F activation during redox transmetallation with silverN,N′‐bis(2,6‐difluorophenyl)formamidinate

AbstractThe trivalent lanthanoid formamidinates, [Yb2(DFForm)4F2(py)2] ⋅ CH3CN (1) (DFForm=N,N′‐bis(2,6‐difluorophenyl)formamidinate), and [La6(DFForm)8F8O(CH3CN)2] ⋅ 6CH3CN (2) have been prepared from redox transmetallation (RT) reactions employing lanthanoid metals and silver formamidinate (AgDFForm) in CH3CN. C−F activation was observed in both reactions. The structure of1is a fluorine bridged dimer with two seven‐coordinate ytterbium metal ions. Surprisingly the lanthanum complex is a trivalent cage with an unexpected central oxygen atom. [La6(DFForm)8F8O(CH3CN)2] ⋅ 6CH3CN (2) formed a 15 membered ring cage of six La atoms, eight F and one O at the centre. There are three different La3+ions in2with two different coordination numbers. All the La atoms are coordinated by four bridging fluorides and the central oxygen.

Stereospecific Csp3 Suzuki–Miyaura Cross-Coupling That Evades β-Oxygen Elimination

Stereospecific Csp3 Suzuki–Miyaura cross-coupling could transform stereochemically complex small molecule synthesis into a simple and broadly accessible process. However, most current methods are not compatible with complex building blocks that represent densely packed, multistereogenic center-containing motifs commonly found in natural products and other complex targets. Here, we report a method that enables the α-methyl-β-hydroxyl motif, which is found in >18 000 natural products as well as other Csp3-rich organic fragments, to be embedded within stereochemically defined secondary alkyl boronic ester building blocks that are readily cross-coupled in a stereospecific manner. The steric effect-mediated decrease in reactivity toward transmetalation and deleterious side reactions associated with the cross-coupling of β-oxygen-containing Csp3 boronic esters are concomitantly addressed using β-aryloxysilyl groups as dual-purpose transmetalation-promoting groups and stable β-oxygen surrogates. Mechanistic studies including real-time HPLC analysis show that a five-membered pinacol siloxaborolate generated in situ is then hydrolyzed to a dihydroxysiloxaborolate that acts as an activated transmetalation partner in a stereospecific process that proceeds with retention of configuration.

One pot synthesis of propargylamines by three component amine-aldehyde-acetylene (A3) coupling catalyzed by neutral Ag(I) and Au(I) and cationic Pd(II) and Ni(II) complexes of a pincer N-heterocyclic carbene

The amine−aldehyde−acetylene (A3) coupling yielding propargylamines was successfully catalyzed by a series of neutral silver and gold complexes, [2,6-bis-(1-(1S)-menthyl-3-methylene-imidazol-2-ylidene)-pyridine]M2Cl2 [M = Ag (2), Au (3)], and cationic palladium and nickel complexes {[2,6-bis-(1-(1S)-menthyl-3-methylene-imidazol-2-ylidene)-pyridine]MCl}X [M = Pd, X = Cl (4), BF4 (5); M = Ni, X = Cl (6), BF4 (7)], stabilized over a new (1R)-(−)-menthyl substituted bis(imidazole) based [CcarbeneNCcarbene] type pincer ligand. The Au(I) (3), Pd(II) (4) and Ni(II) (6) complexes were conveniently synthesized by transmetallation reaction from the Ag(I) analog (2), which was obtained from the N-heterocyclic carbene ligand precursor (1) by treatment with Ag2O. The anion exchange reaction of Pd(II) (4) and Ni(II) (6) with AgBF4 yielded the corresponding Pd(II) (5) and Ni(II) (7) complexes respectively. Mass spectrometry studies suggested the formation of a catalytically active metal acetylide species namely, [NHC]M2(CCPh)Cl [M = Ag (2a), Au (3a)] and {[NHC]M(CCPh)}X [M = Pd, X = Cl (4a), BF4 (5a); M = Ni, X = Cl (6a), BF4 (7a)] (where NHC = 2,6-bis-(1-(1S)-menthyl-3-methylene-imidazol-2-ylidene)-pyridine). which mediates the formation of the propargylamine with a protonated Schiff imine salt produced in situ from an aldehyde and an amine in the single pot reaction.

(CH3 )Al(CH2 )]12 : Methylaluminomethylene (MAM-12).

The molecular structure of enigmatic “poly(aluminium‐methyl‐methylene)” (first reported in 1968) has been unraveled in a transmetalation reaction with gallium methylene [Ga8(CH2)12] and AlMe3. The existence of cage‐like methylaluminomethylene moieties was initially suggested by the reaction of rare‐earth‐metallocene complex [Cp*2Lu{(μ‐Me)2AlMe2}] with excess AlMe3 affording the deca‐aluminium cluster [Cp*4Lu2(μ 3‐CH2)12Al10(CH3)8] in low yield (Cp*=C5Me5). Treatment of [Ga8(CH2)12] with excess AlMe3 reproducibly gave the crystalline dodeca‐aluminium complex [(CH3)12Al12(μ 3‐CH2)12] (MAM‐12). Revisiting a previous approach to “poly(aluminium‐methyl‐methylene” by using a (C5H5)2TiCl2/AlMe3 (1 : 100) mixture led to amorphous solids displaying solubility behavior and spectroscopic features similar to those of crystalline MAM‐12. The gallium methylene‐derived MAM‐12 was used as an efficient methylene transfer reagent for ketones.

Free Difluorobis(pentafluoroethyl)phosphoranide Ion and Its Ligand Properties.

In this contribution, we report on the "free" [P(C2F5)2F2]- ion and its ligand properties in transition metal complex chemistry. For this purpose, Ag[P(C2F5)2F2] was treated with [{(Et2N)3P═N}3P═NHC(CH3)3]Cl ([EtP4H]Cl) to yield [EtP4H][P(C2F5)2F2], featuring a weakly coordinating phosphazenium cation. Due to the weak interaction between the cation and anion, the [P(C2F5)2F2]- ion meets the so-called pseudo-gas-phase conditions. To determine the Tolman electronic parameter, [EtP4H][Ni(CO)3{P(C2F5)2F2}] was prepared from [EtP4H][P(C2F5)2F2] and [Ni(CO)4], facilitating the classification of the P(C2F5)2F2 moiety as a moderately π-acidic ligand. By treatment of [EtP4H][P(C2F5)2F2] with [AuCl(tht)], the neutral tetrahydrothiophene ligand was substituted by the phosphoranide ion, yielding [EtP4H][AuCl{P(C2F5)2F2}]. When Ag[P(C2F5)2F2] was treated with [AuCl(tht)], on the other hand, the chloride was substituted. Transmetalation reactions of this type proved to be an efficient transfer method of the P(C2F5)2F2 moiety, as further demonstrated by the reactions of Ag[P(C2F5)2F2] with [FeCl(CO)2Cp], [FeCl(CO)2Cp*], and [PdCl2(NCMe)2]. Surprisingly, P(C2F5)2F demonstrated fluorinating abilities toward [FeCl(CO)2Cp], [FeCl(CO)2Cp*], [AuCl(tht)], and [PdCl2(NCMe)2]. Apparently, fluorido transition metal complexes were generated in situ under the formation of P(C2F5)2Cl. The fluorido iron and palladium complexes transfer their fluoride ions onto P(C2F5)2F, yielding the respective phosphoranido complexes, featuring the P(C2F5)2F2 moiety.

Imaging of Transmetallation and Chelation Phenomena Involving Radiological Contrast Agents in Mineral-Rich Fruits.

Exogenous heavy metals or non-metallic waste products, for example lanthanide or iodinated contrast media for radiological procedures, may interfere with the biochemical pools in patients and in common food sources, creating an excess buildup of exogenous compounds which may reach toxic levels. Although the mechanisms are unknown, our experiments were designed to test if this toxicity can be attributed to “transmetallation” or “chelation” reactions freeing up lanthanides or chelated transition metals in acidic fruits used as phantoms representing the biologically active and mineral-rich carbohydrate matrix. The rapid breakdown of stable contrast agents have been reported at a lower pH. The interaction of such agents with native metals was examined by direct imaging of contrast infused fresh apples and sweet potatoes using low energy X-rays (40–44 kVp) and by magnetic resonance imaging at 1.5 and 3T. The stability of the exogenous agents seemed to depend on endogenous counterions and biometals in these fruits. Proton spin echo MR intensity is sensitive to paramagnetic minerals and low energy X-ray photons are sensitively absorbed by photoelectric effects in all abundant minerals and were compared before and after the infusion of radiologic contrasts. Endogenous iron and manganese are believed to accumulate due to interactions with exogenous iodine and gadolinium in and around the infusion spots. X-ray imaging had lower sensitivity (detection limit approximately 1 part in 104), while MRI sensitivity was two orders of magnitude higher (approximately 1 part in 106), but only for paramagnetic minerals like Mn and Fe in our samples. MRI evidence of such a release of metal ions from the native pool implicates transmetallation and chelation reactions that were triggered by infused contrast agents. Since Fe and Mn play significant roles in the function of metalloenzymes, our results suggest that transmetallation and chelation could be a plausible mechanism for contrast induced toxicity in vivo.

Copper(II) invigorated EHU-30 for continuous electroreduction of CO2 into value-added chemicals

The doping of zirconium based EHU-30 and EHU-30-NH2 metal–organic frameworks with copper(II) yielded a homogeneous distribution of the dopant with a copper/zirconium ratio of 0.04–0.05. The doping mechanism is analysed by chemical analysis, microstructural analysis and pair distribution function (PDF) analysis of synchrotron total scattering data in order to get deeper insight into the local structure. According to these data, the Cu(II) atoms are assembled within the secondary building unit by a transmetalation reaction, contrarily to UiO-66 series in which the post-synthetic metalation of the MOF takes place through chemical anchorage. The resulting materials doubled the overall performance of the parent compounds for the CO2 electroreduction, while retained stable the performance during continuous transformation reaction.

Group 12 and 13 metal-alkenyl promoted generation of long-chain branching in metallocene-based polyethylene

In situ synthesis of topologically modified linear polyethylenes (PEs) using single-site polymerization catalysis is a challenging task that enables the production of advanced materials with tailored properties. We describe here our investigations aimed at an efficient generation of long-chain branches (LCB) in linear PEs using discrete B-, Al- and Zn-alkenyl co-reagents in combination with homogeneous rac-{EBTHI}ZrCl2 (1)/ or (nBuCp)ZrCl2 (2)/MAO catalytic systems. As corroborated by extensive rheological studies and 13C NMR spectroscopy, Al-and Zn-based reagents promote LCB formation via a two-step mechanism involving both vinylic group insertion and M → Zr transmetallation steps. In striking contrast, the B-alkenyl species was found to form hydrolytically stable B-centred cross-linked PE structures. The Mg-based reagent appeared to be reluctant towards Mg → Zr transmetallation reaction, providing only the products of vinylic group insertion, which after hydrolysis afforded short-chain branched (SCB) PEs. The experimental observations were rationalized by DFT computations.

Online and In Situ Monitoring of the Exchange, Transmetalation, and Cross-Coupling of a Negishi Reaction

We have developed a reaction monitoring method which provides quantitative information through exchange, transmetalation (TM), and cross-coupling for a Negishi reaction. Online HPLC and ReactIR were used as orthogonal techniques to corroborate time-course data through each step. Excellent agreement between the two techniques was observed through monitoring the magnesium/bromine exchange. Quantitative information regarding the TM was gathered via a novel, inline quenching technique facilitated by online HPLC. Quenching reaction aliquots with the electrophile 4-chlorobenzaldehyde allowed us to determine the extent of TM because of its selectivity for reacting with organomagnesiums. After TM, the Negishi reaction was performed and monitored using online LC. Titrating ZnCl2 into a solution of arylmagnesium allowed us to gain insights into zinc speciation in situ. Less than 1 equiv of ZnCl2 was needed to achieve complete TM, evidencing the presence of diorganozincs/arylzincates. Additionally, using substoichiometric quantities of ZnCl2 resulted in higher rates of catalysis for the Negishi reaction.

Combining 2D organic and 1D inorganic nanoblocks to develop free-standing hybrid nanomembranes for conformable biosensors

We report a simple approach to fabricate free-standing perforated 2D nanomembranes hosting well-ordered 1D metallic nanostructures to obtain hybrid materials with nanostructured surfaces for flexible electronics. Nanomembranes are formed by alternatively depositing perforated poly(lactic acid) (PLA) and poly(3,4-ethylenedioxythiophene) layers. Copper metallic nanowires (NWs) were incorporated into the nanoperforations of the top PLA layer by electrodeposition and further coated with silver via a transmetallation reaction. The combination of 2D polymeric nanomembranes and aligned 1D metallic NWs allows merging the flexibility and conformability of the ultrathin soft polymeric nanomembranes with the good electrical properties of metals for biointegrated electronic devices. Thus, we were able to tailor the nanomembrane surface chemistry as it was corroborated by SEM, EDX, XPS, CV, EIS and contact angle. The obtained hybrid nanomembranes were flexible and conformable showing sensing capacity towards H2O2 with good linear concentration range (0.35–10 mM), sensitivity (120 µA cm−2 mM−1) and limit of detection (7 μm). Moreover, the membranes showed good stability, reproducibility and selectivity towards H2O2.

Highly Stretchable and Sensitive Strain Sensor based on Ionogel/Ag Synergistic Conductive Network

AbstractRecently, flexible strain sensors have been intensively studied in order to meet the growing demands of detecting multiscale mechanical deformations. However, it remains a big challenge to integrate high stretchability and high sensitivity in a strain sensor simultaneously. In this study, a highly stretchable and sensitive strain sensor is successfully fabricated by constructing ionogel/silver synergistic conductive network. The transmetalation reaction is utilized to transform the copper atoms in the copper/ionogel nanocomposite into more silver atoms with larger radius, which eliminates the interspace among the nanoparticles, and therefore a silver/ionogel nanocomposite with high conductivity is obtained. Owing to the fragility of the conductive network, the obtained nanocomposite possesses high sensitivity. In addition, as the polymer substrate, the conductive ionogel can connect the crack of the silver conductive network during stretching, endowing the nanocomposite with high stretchability. Hence, the obtained strain sensor exhibits a high sensitivity in a wide sensing range and can detect various human activities. Therefore, this strategy can be envisioned as promising strategy for fabricating high‐performance strain sensors and other flexible electronics.