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All-inorganic tin halide perovskite compounds, such as CsSnI3, have attracted attention in the field of solar cells due to their eco-friendly properties. It is quite a challenge to fabricate high-quality CsSnI3 perovskite films with low defect density due to the low defect tolerance and overquick crystallization growth rate. Herein, we propose a simple yet effective method to modulate the dynamic balance between the growth and nucleation of perovskite crystals for black orthorhombic phase CsSnI3. We found that well-crystallized CsSnI3 thin films can be easily obtained through two-step thermal annealing at low temperatures of 40 °C and 70 °C. We further introduced 1-(4-carboxyphenyl)-2-thiourea to coordinate with surface undercoordinated Sn2+ cations of CsSnI3 thin films through C＝S and C＝O functional groups, significantly decreasing the defect density. The CsSnI3 perovskite solar cells based on a printable c-TiO2/m-TiO2/Al2O3/NiO/carbon mesoporous framework achieved a power conversion efficiency of 8.03% with high reproducibility, which is the best efficiency among those reported for all-inorganic CsSnI3 mesoporous perovskite solar cells to date. Furthermore, the corresponding devices retained 90% of the initial efficiency after 3000 hours of storage in a N2-filled glovebox. [ABSTRACT FROM AUTHOR]

Hydrazone compounds could be highly emissive in the solid state. However, most hydrazone-linking COFs are poorly luminescent. Here we report the enhancement of fluorescence in a 2D hydrazone-linking COF by side chain engineering. Stacking of the bulky and semi-rigid crown ether side chains restricts intramolecular rotation of the backbone around the hydrazone linkers, reducing the thermal dissipation and achieving 20-fold improved emission. [ABSTRACT FROM AUTHOR]

A fluorogenic RNA aptamer nanodevice integrating an entropy-driven RNA amplifier with near-infrared (NIR) light control was developed, affording high contrast and sensitivity for imaging low-abundance mRNA in living cells. The design principle offers a new approach for developing low-background imaging systems for live-cell studies and manipulation. [ABSTRACT FROM AUTHOR]

Carbon dioxide (CO2) capture has attracted considerable attention from both experimental and theoretical chemists. In comparison, carbon disulfide (CS2) activation is less developed. Here, we carry out a thorough comparative density functional theory study to examine the reaction mechanisms of CS2 activation by five-membered heterocycle-bridged P/N frustrated Lewis pairs (FLPs). Calculations suggest that despite a weaker carbon–sulfur bond, all the CS2 activations have higher reaction barriers than the CO2 capture, which could be attributed to electrostatic repulsion between FLPs and CS2 caused by the reversed polarity of C＝S in CS2 rather than the electrostatic attraction in CO2 capture. In addition, aromaticity is found to play an important role in CS2 capture as it stabilizes both the transition states and products in heterocycle-bridged FLPs. All these findings could be useful for experimentalists to realize small molecule activations by FLPs. [ABSTRACT FROM AUTHOR]

Accurate, in situ and long-term electrically monitoring of cell development plays an important role in cell study, which brings in challenges in terms of biocompatibility, processability, and sensing capability of electrochemical sensors. Based on biocompatible conductive polyaniline (PAni) hydrogels, we constructed a flexible sensor with flexible carbon cloth for electrical analysis of living cells. The carbon fiber substrate modified with conductive PAni hydrogels was selected as the electrode to promote the current collection of the sensor. The three dimensional nanostructured mesoporous matrix of PAni hydrogels is favorable for in situ generation of catalytic Pt nanoparticles and cell growth. With these hierarchically nanostructured features, the hydrogel electrochemical sensor was endowed with high sensitivity and selectivity in the detection of H2O2 (with a low detection limit of 1.6 μM in 0.01 M PBS and a wide linear range from 10 μM to 10 mM), and good biocompatibility for cell growth as long as 5 days. The accurate detection of H2O2 released from cells enabled us to differentiate the physiological states of cells and imitate the different stimuli-responsive behavior, which can provide real-time information on cell biological events. With outstanding biocompatibility, operability and repeatability, this strategy can be expanded to the fields of other biosensor fabrication and cell-related biomarker monitoring, which exhibits a broad application potential in bioanalysis catering to new generation sensors. [ABSTRACT FROM AUTHOR]

According to Hückel's and Baird's rules, cyclic species are generally aromatic only either in the lowest singlet state (S0) or in the lowest-lying triplet ππ* excited state (T1). Thus, species with aromaticity both in S0 and T1 states (termed as adaptive aromaticity) are particularly rare. Herein, we carry out density functional theory (DFT) calculations to examine the aromaticity of 16e metallapentalenes containing heteroatoms (N, O). Interestingly, metallazapentalenes show adaptive aromaticity whereas metalloxapentalenes display nonaromaticity in the S0 and T1 states, which is supported by structural, magnetic, and electronic indices. In addition, a series of metallazapentalenes containing strong σ- or π-donor ligands are predicted to achieve adaptive aromaticity. Our findings expand the family of adaptive aromatics significantly, inviting experimental chemists to realize more hetero-metallapentalenes with adaptive aromaticity. [ABSTRACT FROM AUTHOR]

Osmapentalyne and osmapentalene complexes, now termed as carbolong species, have attracted considerable attention due to their novel structures, reactivities, and chelating properties as well as Möbius and adaptive aromaticity. On the other hand, boron monofluoride (BF), a 10-electron diatomic molecule isoelectronic to carbon monoxide (CO), is unstable below 1800 °C in the gas phase, and preparation of its metal complex is particularly challenging. Although the iron complex featuring a terminal BF ligand was synthesized recently, the structure, bonding and aromaticity of metallapentalyne and metallapentalene complexes containing BF ligands remain unclear. Herein, we carry out density functional theory (DFT) calculations to address this issue. The Os–B bond could be considered as a single, double or triple bond depending on the ligands attached to the metal center according to principal interacting orbital (PIO) analysis. The similarity on aromaticity is revealed between CO complexes and BF ones. All these species display aromaticity in the S0 state. For the T1 state, they could be aromatic, nonaromatic or antiaromatic depending on the excitation mode. All these findings could be useful to develop the concept of adaptive aromaticity as well as BF chemistry. [ABSTRACT FROM AUTHOR]

We report the straightforward synthesis of ATP-responsive nanoscale metal azolate framework-7 (MAF-7) for gene/drug codelivery. The MAF-7 functions as (i) the armour to preserve DNAzymes, (ii) an ATP scavenger to lower the intracellular ATP level, and (iii) a built-in Zn2+ arsenal to initiate the biocatalysis of DNAzymes, ultimately inhibiting P-gp expression to enhance chemotherapy. [ABSTRACT FROM AUTHOR]

As a fundamental concept in chemistry, aromaticity has been extended from traditional organics to organometallics. Similarly, hyperconjugative aromaticity (HCA) has also been developed from main group to transition metal systems through the hyperconjugation of the substituents. However, it remains unclear that how the oxidation state of transition metal in the substituents affects the HCA. Herein, we demonstrate via density functional theory calculations that HCA could disappear in indoliums when the Au(I) substituents are changed to the Au(III) ones. By tuning the ligand or cis–trans isomerization, HCA could be regained or enhanced in indoliums containing Au(III) substitutents. [ABSTRACT FROM AUTHOR]

In recent years, two-dimensional (2D) black phosphorus (BP) has been widely applied in many fields, such as (opto)electronics, transistors, catalysis and biomedical applications due to its large surface area, tunable direct bandgap, superior charge carrier mobility, and unique in-plane anisotropic structure. To exploit its full potential and push the limits, studies on functional 2D BP nanostructures fabricated by a variety of methods, such as surface functionalization and hybridization, are rapidly expanding for next-generation devices with unprecedented properties. In this review, firstly, the synthetic techniques and fundamental properties of functional 2D BP nanostructures, including surface-modified 2D BP nanostructures and mixed-dimensional 2D BP-based heterostructures, are systematically summarized. Secondly, the recent progress of functional 2D BP nanostructures in the fields of energy storage and conversion, (opto) electronics, catalysis, sensors, nonlinear photonics, and biomedical applications is highlighted. Last but not least, the challenges and future opportunities in these emerging areas are discussed. We hope that this review can provide fundamental guidance on new designs of high-performance functional 2D BP nanostructures to meet the growing demand of next-generation devices. [ABSTRACT FROM AUTHOR]

The conversion of the ubiquitous greenhouse gas CO2 to valuable organic products is much sought after. Herein, the hydrogenation of CO2 to C1 products with an 80% yield in water is reported using a novel catalyst, porous-silica-supported Au nanoparticles (Au/SiO2). In the presence of a Lewis acid, boric acid, the Au/SiO2 catalyst enables an efficient conversion of amine-captured CO2 to methanol, formate, and formamide. A mechanistic study involving isotopic labelling suggests that methanol production in the catalytic process arises from the direct hydrogenation of formate. Most importantly, this one-pot, two-step process is able to convert CO2 in air at ambient pressures to C1 products in the absence of an organic solvent. Furthermore, the catalyst is readily recycled without further purification or reactivation and shows no significant decrease in catalytic activity after four reaction cycles in a reusability test. [ABSTRACT FROM AUTHOR]

Self-assembled nanomaterials (SANs) exhibit designable biofunctions owing to their tunable nanostructures and modifiable surface. Various constituent units and multi-dimensional structures of SANs provide unlimited possibilities for numerous applications. This review emphasizes the recent development of SANs in the fields of biosensing, bioimaging, and nano-drug engineering. The unit type, design concepts, material advantages, assembly driving force, nanostructure effects, drug loading performance, etc. are discussed and summarized. Finally, we briefly summarize how to assemble unique nanomaterials and point out the key challenges in this field. [ABSTRACT FROM AUTHOR]

The first Zintl cluster containing a distorted Bi6 triangular prism, [Bi6Mo3(CO)9]4−, has been synthesized and structurally characterized. Quantum chemical calculations indicated that the distorted cage cluster features multiple local σ-aromaticity. [ABSTRACT FROM AUTHOR]

Catalytic route electrochemiluminescence (ECL) microscopy enables imaging upper cell membranes with freely diffusing Ru(bpy)32+ as the emitter and nitrogen-doped carbon dots as the nano-coreactants and labels. This strategy provides a vertical resolution when studying the ECL profiles at different heights and realizes the ECL imaging of the externalized phosphatidylserine. [ABSTRACT FROM AUTHOR]

Surface modification of exoelectrogens with photoelectric materials is a promising way for achieving photo-assisted microbial fuel cells (MFCs). However, the poor conductivity of most photoelectric materials inevitably hampers the electron transfer inside bacterial biofilms. Herein, by utilizing the electrostatic layer-by-layer assembly strategy, the conductive Au nanoparticles (NPs) and photo-responsive CdS NPs were alternatively modified onto the surface of Escherichia coli for photo-assisted bioanodes in MFCs. The CdS layer was found to protect the bacterial cells from light illumination-induced inactivation. When the CdS layer coexisted with an outer layer of Au NPs, the modification of the CdS layers can generate photocurrent without any loss of biocurrent, because the outer Au layer could serve as a conductive channel for the photoelectron and bioelectron transfer between each bacterium. But the increase of CdS layers failed to further improve the photocurrent, implying that the light was inaccessible to the inner CdS layer. This work brings a universal way to fabricate conductive and photo-responsive bacteria, which would deepen the application of cell-surface modification technology in photo-assisted MFCs. [ABSTRACT FROM AUTHOR]

Aromaticity and hyperconjugation are two fundamental concepts in organic chemistry. By combination of the two concepts together, the resulting hyperconjugative aromaticity has attracted considerable attention from both theoretical and computational chemists. However, previous studies are mainly focused on the main group chemistry. For the hyperconjugative aromaticity in the transition metal chemistry, the studies are limited to groups 10 and 11. Here, we demonstrate that hyperconjugative aromaticity can be achieved in 2H-pyrrolium and cyclopentadiene containing group 9 transition metal substituents via density functional theory calculations. More importantly, further studies reveal that the metal–metal bonding interaction between two substituents could reduce hyperconjugative aromaticity, whereas the bridged carbonyl ligands will enhance aromaticity due to the significantly elevated HOMO orbital of the CR2 fragment. All these findings not only extend the scope of the concept of hyperconjugative aromaticity but also are helpful to develop the chemistry of metalla-aromatics. [ABSTRACT FROM AUTHOR]

In the past few decades, the construction of discrete supramolecular double-metallacycles has attracted wide interest because of their unique structures and their potential applications in photoelectric materials. Since some progress has been made in this area, it is time to summarize the progress of discrete supramolecular double-metallacycles. In this review, we will briefly introduce the synthetic strategy of discrete supramolecular double-metallacycles. In addition, we will discuss the design principles, preparation methods, optical properties, and functions of these discrete supramolecular double-metallacycles. [ABSTRACT FROM AUTHOR]

Disilene has attracted considerable interest due to the trans-bending geometry which is significantly different from the planar alkene. However, the equilibrium between disilene and isomeric silylsilylene has not been fully understood. Here, we report a density functional theory (DFT) study on this equilibrium. Calculations reveal significant effects of substituent, aromaticity and base. Specifically, the parent disilene is thermodynamically more stable than the isomeric silylene. When the methoxy substituent is introduced, the corresponding silylene becomes thermodynamically more stable, which could be rationalized by the Bent's rule. Interestingly, disilabenzene becomes thermodynamically more stable than the isomeric silylene when the concept of aromaticity is taken into account. Finally, once the base is introduced, the silylene could become thermodynamically more stable than the isomeric disilabenzene. The kinetic effect of the tautomerization with several typical substituents (F, Me and OMe) has also been investigated. Some species with a bridged form have been found to have a higher thermodynamic stability over the nonbridged ones. All these findings could be particularly useful to develop the chemistry of disilenes and silylenes. [ABSTRACT FROM AUTHOR]

Surface modification of exoelectrogenic bacteria represents an impressive development in microbial fuel cells (MFCs), because every bacterial cell can maintain an intimate contact with the anodic material for upgrading the performance. Here, Au and Fe3O4 co-modified Shewanella oneidensis MR-1 is developed for the bioanode of MFCs. The co-modified bacterial cells are synthesized by the biomineralization of Au nanoparticles (NPs) and the electrostatic attraction of Fe3O4 NPs to the cell surfaces. The highly conductive Au NPs accelerate electron transfer inside the biofilm and between the biofilm/electrode interfaces. Meanwhile, the bioaffinity of Fe3O4 NPs can help to retain the bacterial metabolic activity for a long time. More importantly, the magnetic activity of Fe3O4 NPs allows the fast capture of co-modified bacteria onto the magnetic substrate electrode, largely improving the bacterial loading amount and decreasing the time for bacterial colonization. As a result of this trifunctional modification, the magnet-assisted bioanode fabricated with co-modified bacteria is far superior to that with native bacteria in start-up, stability and output performance. This work not only deepens the application of cell-surface modification technology in MFCs but also brings bacterial cells into the stage of multi-step modification. [ABSTRACT FROM AUTHOR]

Baird's rule has been applied to a large scope of organic molecular systems for rationalizing the aromaticity reversal in the lowest-lying triplet state. In this study, we demonstrate that Baird's rule can also be extended to all-metal systems with σ- and π-aromaticity. [ABSTRACT FROM AUTHOR]

Polarized light sources play a significant role in a growing number of applications: from general illumination to highly efficient displays. Solution-processed polarized light-emitting diodes (pol-LEDs) have attracted remarkable interest because of the wide choice of emissive materials, capability to be solution-processed and easy fabrication. We first classify organic pol-LEDs into two categories according to their aligning techniques, including (1) alignment without an oriented substrate and (2) alignment on an oriented substrate. Recent progress in aligning techniques, emissive materials, substrate materials, device performances and polarizing properties is summarized. We also discuss pol-LEDs based on emissive materials of one-dimensional (1D) II–VI and lead halide perovskite nanomaterials. Finally, an outlook is provided on research trends in the development of solution-processed pol-LEDs. [ABSTRACT FROM AUTHOR]

As nonspecific adsorption or biofouling has obvious side effects on the selectivity, it is a great challenge for cytosensors to detect target cells in practical biological samples. In this study, we first propose the design and synthesis of an antifouling photoelectrode. The antifouling photoelectrode not only has the desired photocurrent response, but also possesses an unexpected antifouling capability of resisting nonspecific adsorption of biomolecules. Herein, the PEDOT-HPG/SnS/ZnO-NT antifouling photoelectrode was formed and a robust photoelectrochemical cytosensor with enhanced sensitivity and selectivity has been demonstrated. [ABSTRACT FROM AUTHOR]

Anisotropic films composed of aligned CsPbBr3 nanowires (NWs) have been successfully fabricated using a mechanical rubbing method. The films with a dense and uniform morphology show polarization photoluminescence (PL) behavior. Combined with an optimal device structure, a polarized light-emitting diode (LED) with a turn-on voltage as low as 6.5 V was obtained. [ABSTRACT FROM AUTHOR]

Pentafulvenes are dipolar hydrocarbons since they shift their π-electrons to achieve Hückel aromaticity and thus the electron donating groups at the exocyclic position can enhance their aromaticity. Silapentafulvenes are analogues of pentafulvene formed by the replacement of the carbon atoms at the exocyclic C＝C double bond with a silicon atom in pentafulvene. It remains unclear how the aromaticity of 5-silapentafulvenes and 6-silapentafulvenes can be changed due to the polarization of the C＝Si double bond. Here we perform density functional theory calculations and reveal the increased aromatic character in 6-silapentafulvenes and the reduced aromaticity of 5-silapentafulvenes in the ground state. In addition, the origin of the relative thermodynamic stability of the silapentafulvene isomers can be attributed to the bond dissociation energy (BDE) of the exocyclic bond. More interestingly, some triplet ground state 5-silapentafulvene species are predicted by introducing amino groups on the ring, which is supported by the coupled cluster calculations. Our findings could be useful for experimentalists to realize silaaromatics. [ABSTRACT FROM AUTHOR]

Waterborne polyurethane (WPU) based polymeric dyes with anthraquinone chromophores were developed to realize coloring textiles and improve color fastness. The preparation of polymeric dyes through the reaction of 1,4-diamino-2,3-diphenoxyanthraquinone (DV26) and NCO-terminated prepolymer was monitored via UV absorption spectroscopy. With the progress of the reaction, the intensity of the absorption peak of the primary amine group at 586 nm decreased as a function of reaction time. Thus, the conversion of DV26 at different times and the reaction end point could be determined. The reaction mechanism corresponded to an autocatalytic reaction equation, basically. In addition, the results of performance tests showed that the polymeric dyes exhibited good emulsion stability, ultra-low migration percentages, good water resistance and excellent thermal stability. Moreover, the application properties of DWPU on coated polyester fabrics were satisfactory. [ABSTRACT FROM AUTHOR]

Following the efficient performance of metal–organic frameworks (MOFs) as recognition elements in gas sensors, biosensors based on MOFs are now being investigated to capture and quantify potential cancer biomarkers, such as circulating tumor cells (CTCs), nucleic acids and proteins. The current status of MOF-based biosensors in the detection of early stages of cancer is in its infancy, although it has significantly emerged since the beginning of this decade. That said, salient research has been conducted in the past five years to utilize the distinctive porous crystalline structure of MOFs for highly sensitive and selective detection of cancer biomarkers. In this pursual, MOFs designed with bimetallic assembly, doped with magnetic nanoparticles, coated with polymers, and even conjugated with peptides or oligonucleotides have shown promising outcomes in detecting CTCs, nucleic acids and proteins. In particular, aptamer-conjugated MOFs are able to perform at a lower limit of detection down to the femtomolar, implying their efficacy for the point of care testing in clinical trials. In this way, aptasensors based on aptamer-conjugated MOFs present a newer sub-branch, to be coined as a MOFTA sensor in the current review. Considering the emerging progress and promising outcomes of MOFTA sensors as well as a variety of MOF-based techniques of detecting cancer biomarkers, this review will highlight their significant advances and related aspects in the recent five years on the context of detecting CTCs, nucleic acids and proteins for the early-stage detection of cancer. [ABSTRACT FROM AUTHOR]

As a series of important metal materials, rare earth elements and their related derivative compounds have received significant attention because of their narrow emission bands, noncytotoxicity, excitation of multiple fluorescence colors and electrochemical properties. These unique properties endow rare earth-based nanomaterials with great potential for application in various fields such as in supercapacitors, batteries, sensors, devices and solar cells. This review presents a general description of the electrochemical properties of rare earth-based nanomaterials. The developments and improvements of their electrochemical applications in electrochemical sensors for the detection of small biomolecules and DNA, supercapacitors, batteries and electrochemical catalysis towards the hydrogen evolution reaction have also been discussed. [ABSTRACT FROM AUTHOR]