Lisa

Enantioselective cobalt‐catalyzed hydrosilylation/cyclization of 1,6‐enynes is developed to access synthetically versatile chiral alkylsilanes with a catalyst generated in situ from Co(acac)₂ and (R,S _p)‐Josiphos. A wide range of 1,6‐enynes react to afford the corresponding alkylsilanes in good yields with excellent enantioselectivity (up to >99 % ee).

Abstract

We report an enantioselective cobalt‐catalyzed hydrosilylation/cyclization reaction of 1,6‐enynes with secondary and tertiary hydrosilanes employing a catalyst generated in situ from the combination of Co(acac)₂ and (R,S_p )‐Josiphos. A wide range of oxygen‐, nitrogen‐, and carbon‐tethered 1,6‐enynes reacted with Ph₂SiH₂, (EtO)₃SiH, or (RO)₂MeSiH to afford the corresponding chiral organosilane products in high yields and up to >99 % ee. This cobalt‐catalyzed hydrosilylation/cyclization also occurred with prochiral secondary hydrosilane PhMeSiH₂ to yield chiral alkylsilanes containing both carbon‐ and silicon‐stereogenic centers with excellent enantioselectivity, albeit with modest diastereoselectivity. The chiral organosilane products from this cobalt‐catalyzed asymmetric hydrosilylation/cyclization could be converted to a variety of chiral five‐membered heterocyclic compounds by stereospecific conversion of their C−Si and Si−H bonds without loss of enantiopurity.

In article number 2002958 Won‐Sub Yoon, and co‐workers explore various structural and electrochemical phenomena associated with elemental segregations in Li_1.233Mo_0.467Cr_0.3O₂ disordered rock‐salt cathode material. The impact of a unique Mo–Mo bond on the lattice stability is investigated. A separation between Mo/Li‐rich and Cr/Li‐poor domains is observed. Based on this, the mechanisms of the domain‐dependent kinetics, asymmetric Li⁺ diffusion, and linked hysteresis/degradation processes are explained.

A strategy to micropattern 2D materials on large‐scale flexible substrates using a direct polymer curing transfer method is demonstrated. Graphene microchannels on polymer substrates exhibit ultrahigh effective self‐heating under an applied bias voltage of less than 10 V. An entirely flexible and transparent chemical sensor array based on graphene micropatterns successfully discriminates gas species under the self‐activated state without external heating.

Abstract

2D materials, such as graphene, exhibit great potential as functional materials for numerous novel applications due to their excellent properties. The grafting of conventional micropatterning techniques on new types of electronic devices is required to fully utilize the unique nature of graphene. However, the conventional lithography and polymer‐supported transfer methods often induce the contamination and damage of the graphene surface due to polymer residues and harsh wet‐transfer conditions. Herein, a novel strategy to obtain micropatterned graphene on polymer substrates using a direct curing process is demonstrated. Employing this method, entirely flexible, transparent, well‐defined self‐activated graphene sensor arrays, capable of gas discrimination without external heating, are fabricated on 4 in. wafer‐scale substrates. Finite element method simulations show the potential of this patterning technique to maximize the performance of the sensor devices when the active channels of the 2D material are suspended and nanoscaled. This study contributes considerably to the development of flexible functional electronic devices based on 2D materials.

Poor control of the morphology of hybrid metal organic heterostructures and devices can lead to scientific misunderstandings. Ferromagnetic nuclear resonance is used herein, to investigate organic layers sandwiched between ferromagnetic metallic electrodes. For zinc tetraphenyl porphyrin, 15 monolayers of organics are necessary to form continuous molecular films. The organic layers exhibit distinct morphologies depending on the ferromagnetic metallic underlayer.

Abstract

Physical properties of magnetic nanostructures and devices strongly depend on the morphological characteristics of their various components. This is especially true and becomes particularly complex in hybrid nanostructures, where soft organic molecules are at the vicinity of ferromagnetic metallic films. The supramolecular architecture of molecular films embedded between Fe and Co layers is investigated by ferromagnetic nuclear resonance (FNR). With such sample architecture, the presence of pin holes in the organic layers is detected by FNR contributions in a specific spectral range. The methodology that is developed allows the probing of the continuity and the packing of zinc tetraphenyl porphyrin (ZnTPP) molecular films between the Co and Fe films. The experimental results suggest that, regardless of the nature of the ferromagnetic underlayer, at least 15 monolayers of ZnTPP are necessary to form continuous and pin‐hole free molecular films. In addition, quantitative analyses show that ZnTPP layers exhibit distinct morphologies that are dependent on the nature of the ferromagnetic metallic underlayer.

An accurate cancer diagnosis platform is established through comprehensive profiling of different types of exosomal biomarkers (surface proteins and miRNAs) with 3D microfluidic chip, which works in conjunction with quantum dot labeling and vesicle fusion technology. The chip can not only accurately distinguish cancer cells and normal cells, but also successfully discriminate cancer cell subtypes and monitor cancer stage.

Abstract

Exosomes are recognized as promising biomarkers for early cancer diagnosis and prognosis owing to a large amount of biological information they carried. But the key is that single type of exosomal biomarker analysis is not sufficient enough for accurate cancer diagnosis and stage monitoring due to the insufficient information and high false positive signal. To address the challenge, here simultaneous in situ detection of different types of exosomal biomarkers (surface proteins: CD81, ephrin type‐A receptor 2, and carbohydrate antigen 19‐9; miRNAs: miR‐451a, miR‐21, and miR‐10b) is conducted with a 3D microfluidic chip, which works in conjunction with quantum dot (QD) labeling and vesicle fusion technology. After exosomes are efficiently captured by the microfluidic chip, the quantification of multiple exosomal proteins is achieved by using three kinds of QDs with the same excitation and different emission wavelengths, and virus‐mimicking fusogenic vesicles encapsulating three exquisitely engineered molecular beacons are introduced for ultrasensitive detection of multiple exosomal miRNAs without requiring RNA extraction. Through comprehensive profiling different types of exosomal biomarkers, the false positive rate is substantially avoided and the accuracy of cancer diagnosis and stage monitoring is improved to ≈100%, which are critical to cancer effective treatment and favorable prognosis.

Nature Communications, Published online: 30 October 2020; doi:10.1038/s41467-020-19365-w

Nature Communications, Published online: 18 November 2020; doi:10.1038/s41467-020-19662-4

Poly(allylamine) passivated black phosphorus on laser‐engraved graphene (BP@LEG) composite outperforms high‐performance temperature and strain sensitive material. A novel approach of fabrication of temperature–strain hybridized sensor based on BP@LEG as a functional material in a single sensor layout is reported for the measurement of skin temperature and various human‐body‐induced deformations, suggesting the suitability of the sensor for e‐skin.

Abstract

Smart electronic skin (e‐skin) requires the easy incorporation of multifunctional sensors capable of mimicking skin‐like perception in response to external stimuli. However, efficient and reliable measurement of multiple parameters in a single functional device is limited by the sensor layout and choice of functional materials. The outstanding electrical properties of black phosphorus and laser‐engraved graphene (BP@LEG) demonstrates a new paradigm for a highly sensitive dual‐modal temperature and strain sensor platform to modulate e‐skin sensing functionality. Moreover, the unique hybridized sensor design enables efficient and accurate determination of each parameter without interfering with each other. The cationic polymer passivated BP@LEG composite material on polystyrene‐block‐poly(ethylene‐ran‐butylene)‐block‐polystyrene (SEBS) substrate outperforms as a positive temperature coefficient material, exhibiting a high thermal index of 8106 K (25–50 °C) with high strain sensitivity (i.e., gauge factor, GF) of up to 2765 (>19.2%), ultralow strain resolution of 0.023%, and longer durability (>18 400 cycles), satisfying the e‐skin requirements. Looking forward, this technique provides unique opportunities for broader applications, such as e‐skin, robotic appendages, and health monitoring technologies.

In article number 2004285, Jordan G. McCall, Jae‐Woong Jeong, and co‐workers introduce a new technique stemming from 3D printing technology for the low‐cost, mass production of rapidly customizable optogenetic neural probes. This facile, rapid manufacturing technique with on‐the‐fly design customizability yields biocompatible and functionally robust neural interfacing devices.