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The reaction of preassembled Cu(I) bimetallic units {Cu 2 (dppm) 2 } and {Cu 2 (dppa) 2 } (dppm: bis(diphenylphosphino)methane and dppa: bis(diphenylphosphino)amine) with pseudohalide linkers (azido, dicyanamide, and tricyanomethanide) allows for the quantitative and selective preparation of three discrete tetrametallic metallacycles of formula [Cu 4 (μ 2 -dppm) 4 (N 3 ) 2 ](PF 6 ) 2 , [Cu 4 (μ 2 -dppm) 4 (N(CN) 2 ) 2 ](PF 6 ) 2 , and [Cu 4 (μ 2 -dppm) 4 (C(CN) 3 ) 4 ]. To explore further the impact of the linker on the architecture and dimensionality of the molecular edifice, the study was extended to more sophisticated tetradentate cyanocarbanion ligands (tcnsMe - : 2-(methylthio)-1,1,3,3-propanetetracarbonitrile and tcnsEt - : 2-(ethylthio)-1,1,3,3-propanetetracarbonitrile). Three ladder-like one-dimensional coordination polymers and an octametallic metallacycle have been obtained. The careful comparison of the metric and geometrical intramolecular and intermolecular parameters observed in this series of seven derivatives allows for rationalization of their molecular architectures. The subtle balance between the length and steric hindrance of the ligand and the formation of noncovalent interaction networks greatly influences the topology and dimensionality of the resulting assemblies and will be discussed hereafter. The photophysical properties of these seven polymetallic Cu(I) compounds have also been also studied.

The incorporation of cerium-zinc bimetallic oxide (CeZnO x ) nanostructures in sulfonated poly(2,6-dimethyl-1,4-phenylene oxide) (SPPO) membranes holds promise in an enhanced and durable fuel cell performance. This investigation delves into the durability and efficiency of SPPO membranes intercalated with CeZnO x nanostructures by varying the filler loading of 1, 2, and 3% (w/w). The successful synthesis of CeZnO x nanostructures by the alkali-aided deposition method is confirmed by wide-angle X-ray diffraction spectroscopy (WAXS), Raman spectroscopy, field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) analyses. CeZnO x @SPPO nanocomposite membranes are fabricated using a solution casting method. The intricate interplay of interfacial adhesion and coupling configuration between three-dimensional CeZnO x and sulfonic moieties of the SPPO backbone yields an enhancement in the bound water content within the proton exchange membranes (PEMs). This constructs simultaneously an extensive hydrogen bonding network intertwined with the proton transport channels, thereby elevating the proton conductivity ( K m ). The orchestrated reversible redox cycling involving Ce 3+ /Ce 4+ enhances the quenching of aggressive radicals, aided by Zn 2+ , promoting oxygen deficiency and Ce 3+ concentration. This synergistic efficacy ultimately translates into composite PEMs characterized by a mere 4% mass loss and a nominal 6% decrease in K m after rigorous exposure to Fenton's solution. Remarkably, an improved power density of 403.2 mW/cm 2 and a maximum current density of 1260.6 mA/cm 2 were achieved with 2% loading of CeZnO x (SPZ-2) at 75 °C and 100% RH. The fuel cell performance of SPZ-2 is 74% higher than its corresponding pristine SPPO membrane.

Photocatalytic N 2 fixation has emerged as one of the most useful ways to produce NH 3 , a useful asset for chemical industries and a carbon-free energy source. Recently, significant progress has been made toward designing efficient photocatalysts to achieve this objective. Here, we introduce a highly active type-II heterojunction fabricated via integrating two-dimensional (2D) nanosheets of exfoliated g-C 3 N 5 with nickel-chromium layered double hydroxide (NiCr-LDH). With an optimized loading of NiCr-LDH on exfoliated g-C 3 N 5 , excellent performance is realized for green ammonia synthesis under ambient conditions without any noble metal cocatalyst(s). Indeed, the g-C 3 N 5 /NiCr-LDH heterostructure with 2 wt % of NiCr-LDH (CN-NCL-2) exhibits an ammonia yield of about 2.523 mmol/g/h, which is about 7.51 and 2.86 times higher than that of solo catalysts, i.e., NiCr-LDH (NC-L) and exfoliated g-C 3 N 5 (CN-5), respectively, where methanol is used as a sacrificial agent. The enhancement of NH 3 evolution by the g-C 3 N 5 /NiCr-LDH heterostructure can be attributed to the efficient charge transfer, a key factor to the photocatalytic N 2 fixation rate enhancement. Additionally, N 2 vacancies present in the system help adsorb N 2 on the surface, which improves the ammonia production rate further. The best-performing heterostructure also shows long-term stability with the NH 3 production rate remaining nearly constant over 20 h, demonstrating the excellent robustness of the photocatalyst.

Establishment of an efficient and robust artificial photocatalytic system to convert solar energy into chemical fuels through CO 2 conversion is a cherished goal in the fields of clean energy and environmental protection. In this work, we have explored an emergent low- Z nitrogen-rich carbon nitride material g-C 3 N 5 (analogue of g-C 3 N 4 ) for CO 2 conversion under visible light illumination. A significant enhancement of the CH 4 production rate was detected for g-C 3 N 5 in comparison to that of g-C 3 N 4 . Notably, g-C 3 N 5 also showed a very impressive selectivity of 100% toward CH 4 as compared to 21% for g-C 3 N 4 . The photocatalytic CO 2 conversion was performed without using sacrificial reagents. We found that 1% K doping in g-C 3 N 5 enhanced its performance even further without compromising the selectivity. Moreover, 1% K-doped g-C 3 N 5 also exhibited better photostability than undoped g-C 3 N 5. We have also employed density functional theory calculation-based analyses to understand and elucidate the possible reasons for the better photocatalytic performance of K-doped g-C 3 N 5 .

Here, we have reported the synthesis of three-dimensional, mesoporous, nano-SnO 2 cores encapsulated in nonstoichiometric SnO 2 shells grown by chemical as well as physical synthesis procedures such as plasma-enhanced chemical vapor deposition, followed by functionalization with reduced graphene oxide (rGO) on the surface. The main motif to fabricate such morphology, i.e., core-shell assembly of burflower-like SnO 2 nanobid is to distinguish gases quantitatively at reduced operating temperatures. Electrochemical results reveal that rGO anchored on SnO 2 surface offers excellent gas detection performances at room temperature. It exhibits outstanding H 2 selectivity through a wide range, from ∼10 ppm to 1 vol %, with very little cross-sensitivity against other similar types of reducing gases. Good recovery as well as prompt responses also added flair in its quality due to the highly mesoporous architecture. Without using any expensive dopant/catalyst/filler or any special class of surfactants, these unique SnO 2 mesoporous nanostructures have exhibited exceptional gas sensing performances at room temperature and are thus helpful to fabricate sensing devices in most cost-effective and eco-friendly manner., Competing Interests: The authors declare no competing financial interest.

Preparation of highly luminescent glasses involves expensive and complicated processes and usually requires high temperature. In this work, we show that luminescent silicon (Si) nanoparticle (NP)- embedded silicate gel glasses can be developed under near-ambient conditions by a remarkably simple, one-pot strategy, without using any sophisticated instrumentation or technique. Simultaneous hydrolysis and reduction of (3-aminopropyl)triethoxysilane leads to the formation of colloidal Si nanocrystals that can be transformed to a glassy phase upon slow evaporation followed by freezing. Structural investigations reveal the formation of a sodium silicate gel glass framework having discernible shear bands, along with embedded Si NPs. High photoluminescence quantum yield (ca. 35-40%), low glass-transition temperature ( T g ≈ 66-73 °C), strain-tolerant mechanical stability, and inexpensive preparation make the glass attractive for applications as display materials and photonic converters.

We demonstrate a novel approach for rapid, selective, and sensitive detection of heavy metals using a solid-phase bioactive lab-on-paper sensor that is inkjet printed with sol-gel entrapped reagents to allow colorimetric visualization of the enzymatic activity of β-galactosidase (B-GAL). The bioactive paper assay is able to detect a range of heavy metals, either alone or as mixtures, in as little as 10 min, with detection limits as follows: Hg(II) = 0.001 ppm; Ag(I) = 0.002 ppm, Cu(II) = 0.020 ppm; Cd(II) = 0.020 ppm; Pb(II) = 0.140 ppm; Cr(VI) = 0.150 ppm; Ni(II) = 0.230 ppm. The paper-based assay was immune to interferences from nontoxic metal ions such as Na(+) or K(+), could be used to detect heavy metals that were spiked into tap water or lake water, and provided quantitative data that was in agreement with values obtained by atomic absorption. With the incorporation of standard chromogenic metal sensing reagents into a multiplexed bioactive paper sensor, it was possible to identify specific metals in mixtures, albeit with much lower detection limits than were obtained with the enzymatic assay. The paper-based sensor should be valuable for rapid, on-site screening of trace levels of heavy metals in resource limited areas and developing countries.

A reagentless bioactive paper-based solid-phase biosensor was developed for detection of acetylcholinesterase (AChE) inhibitors, including organophosphate pesticides. The assay strip is composed of a paper support (1 x 10 cm), onto which AChE and a chromogenic substrate, indophenyl acetate (IPA), were entrapped using biocompatible sol-gel derived silica inks in two different zones (e.g., sensing and substrate zones). The assay protocol involves first introducing the sample to the sensing zone via lateral flow of a pesticide-containing solution. Following an incubation period, the opposite end of the paper support is placed into distilled deionized water (ddH(2)O) to allow lateral flow in the opposite direction to move paper-bound IPA to the sensing area to initiate enzyme catalyzed hydrolysis of the substrate, causing a yellow-to-blue color change. The modified sensor is able to detect pesticides without the use of any external reagents with excellent detection limits (bendiocarb approximately 1 nM; carbaryl approximately 10 nM; paraoxon approximately 1 nM; malathion approximately 10 nM) and rapid response times (approximately 5 min). The sensor strip showed negligible matrix effects in detection of pesticides in spiked milk and apple juice samples. Bioactive paper-based assays on pesticide residues collected from food samples showed good agreement with a conventional mass spectrometric assay method. The bioactive paper assay should, therefore, be suitable for rapid screening of trace levels of organophosphate and carbamate pesticides in environmental and food samples.

There is an increasing interest in new strategies to rapidly detect analytes of clinical and environmental interest without the need for sophisticated instrumentation. As an example, the detection of acetylcholinesterase (AChE) inhibitors such as neurotoxins and organophosphates has implications for neuroscience, drug assessment, pharmaceutical development, and environmental monitoring. Functionalization of surfaces with multiple reagents, including enzymes and chromogenic reagents, is a critical component for the effective development of "dipstick" or lateral flow biosensors. Herein, we describe a novel paper-based solid-phase biosensor that utilizes piezoelectric inkjet printing of biocompatible, enzyme-doped, sol-gel-based inks to create colorimetric sensor strips. For this purpose, polyvinylamine (PVAm, which captures anionic agents) was first printed and then AChE was overprinted by sandwiching the enzyme within two layers of biocompatible sol-gel-derived silica on paper. AChE inhibitors, including paraoxon and aflatoxin B1, were detected successfully using this sensor by measuring the residual activity of AChE on paper, using Ellman's colorimetric assay, with capture of the 5-thio-2-nitrobenzoate (TNB(-)) product on the PVAm layer. The assay provided good detection limits (paraoxon, approximately 100 nM; aflatoxin B1, approximately 30 nM) and rapid response times (<5 min). Detection could be achieved either by eye or using a digital camera and image analysis software, avoiding the need for expensive and sophisticated instrumentation. We demonstrate that the bioactive paper strip can be used either as a dipstick or a lateral flow-based biosensor. The use of sol-gel-based entrapment produced a sensor that retained enzyme activity and gave reproducible results after storage at 4 degrees C for at least 60 days, making the system suitable for storage and use in the field.

Monitoring of excitation activity of nerve cells is very useful for not only brain research but also assessment of the effects of various chemicals, including drugs and toxins. We previously reported a novel enzyme-luminescence method for real-time monitoring of l-glutamate release from C6 glioma cells with high levels of sensitivity ( approximately 10 nM) and temporal resolution (<1 s) using a luminescence plate reader. In the present study, we tested the applicability of this novel system for assessment of effects of drugs in vitro. Several drugs (e.g., veratridine and 4-aminopyridine) were administered to C6 glioma cells for inducing glutamate release. Moreover, antagonists of voltage-dependent Ca (2+) channels (e.g., nifedipine, flunarizine, and NiCl 2) and Na (+) channels (e.g., carbamazepine and lidocaine) were applied separately for evaluating the effects of these chemicals on glutamate release from the cells. The combined effect of carbamazepine and lidocaine was also investigated by using our method, and the combined effect was found to be more potent than that of single drug administration. These results indicated that the glutamate release from C6 cells was modulated by these drugs in a way similar to that found by using several conventional analytical techniques. We therefore conclude that the developed monitoring system for real-time detection of dynamic l-glutamate release from cells could be very useful for application to assessment of drugs acting on the nervous system.