An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
Molecular de-aggregation was observed at the air/water interface of aqueous microdroplets. We probed this phenomenon using dyes such as Rhodamine 6G (R6G), Rhodamine B, acridine orange, and fluorescein, which show aggregation-induced shift in fluorescence. The fluorescence micrographs of microdroplets derived from the aqueous solutions of these dyes show that they are monomeric at the air/water interface, but highly aggregated at the core. We propose that rapid evaporation of the solvent influences the de-aggregation of molecules at the air-water interface of the microdroplets.
Atomically precise nanomaterials with tunable solid-state luminescence attract global interest. In this work, we present a new class of thermally stable isostructural tetranuclear copper nanoclusters (NCs), shortly Cu4@oCBT, Cu4@mCBT and Cu4@ICBT, protected by nearly isomeric carborane thiols: ortho-carborane-9-thiol, meta-carborane-9-thiol and ortho-carborane 12-iodo 9-thiol, respectively. They have a square planar Cu4 core and a butterfly-shaped Cu4S4 staple, which is appended with four respective carboranes. For Cu4@ICBT, strain generated by the bulky iodine substituents on the carboranes makes the Cu4S4 staple flatter in comparison to other clusters. High-resolution electrospray ionization mass spectrometry (HR ESI-MS) and collision energy-dependent fragmentation, along with other spectroscopic and microscopic studies, confirm their molecular structure. Although none of these clusters show any visible luminescence in solution, bright μs-long phosphorescence is observed in their crystalline forms. The Cu4@oCBT and Cu4@mCBT NCs are green emitting with quantum yields (Φ) of 81 and 59%, respectively, whereas Cu4@ICBT is orange emitting with a Φ of 18%. Density functional theory (DFT) calculations reveal the nature of their respective electronic transitions. The green luminescence of Cu4@oCBT and Cu4@mCBT clusters gets shifted to yellow after mechanical grinding, but it is regenerated after exposure to solvent vapour, whereas the orange emission of Cu4@ICBT is not affected by mechanical grinding. Structurally flattened Cu4@ICBT didn't show mechanoresponsive luminescence in contrast to other clusters, having bent Cu4S4 structures. Cu4@oCBT and Cu4@mCBT are thermally stable up to 400 °C. Cu4@oCBT retained green emission even upon heating to 200 °C under ambient conditions, while Cu4@mCBT changed from green to yellow in the same window. This is the first report on structurally flexible carborane thiol appended Cu4 NCs having stimuli-responsive tunable solid-state phosphorescence.
An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
Abstract The creation of micrometer‐sized sheets of silver at the air–water interface by direct deposition of electrospray‐generated silver ions (Ag + ) on an aqueous dispersion of reduced graphene oxide (RGO), in ambient conditions, is reported. In the process of electrospray deposition (ESD), an electrohydrodynamic flow is created in the aqueous dispersion, and the graphene sheets assemble, forming a thin film at the air–water interface. The deposited Ag + coalesce to make single‐crystalline Ag sheets on top of this assembled graphene layer. Fast neutralization of Ag + forming atomic Ag, combined with their enhanced mobility on graphene surfaces, presumably facilitates the growth of larger Ag clusters. Moreover, restrictions imposed by the interface drive the crystal growth in 2D. By controlling the precursor salt concentration, RGO concentration, deposition time, and ion current, the dimensionality of the Ag sheets can be tuned. These Ag sheets are effective substrates for surface‐enhanced Raman spectroscopy (SERS), as demonstrated by the successful detection of methylene blue at nanomolar concentrations.
The Gibbs free energy difference between seawater and river water can be tapped by selective ion transport across charged nanochannels, referred to as reverse electrodialysis (RED). However, existing single pore and micro/nanofluidic RED systems have shown poor prospects for scalability and practical implementation. Herein, we present a macroscopic RED system, utilizing a cation-selective membrane or an anion-selective membrane. The membranes comprise reduced graphene oxide (rGO) nanosheets decorated uniformly with TiO2 nanoparticles. The nanosheets are covalently functionalized with polystyrene (PS) and subsequently linked to sulfonate or quaternary amine functional groups to obtain cation and anion selectivity, respectively. The membranes show excellent ion transport properties along with high power densities demonstrated under artificial salinity gradients. The cation-exchange membrane (CEM) delivered a power density of 448.7 mW m–2 under a 500-fold concentration gradient, while the anion-exchange membrane (AEM) produced a substantial power output of 177.8 mW m–2 under a similar gradient. The efficiencies ranged from 10.6% to 42.3% for CEM and from 9.7% to 46.1% in the case of AEM. Testing under varying pH conditions revealed higher power output under acidic conditions and substantial power output across the entire pH range, rendering them practically viable for sustainable energy harvesting in acidic and alkaline wastewaters.
Graphene oxide and its derivatives are an excellent substrate for pre-concentrating and recovering uranium in water. However, the need for a scalable and affordable method for producing graphene oxide has hindered its field applications. Also, there is a need to develop a sustainable approach to recycling spent adsorbents and prevent the nanomaterials from entering the waste stream. In this context, this paper studies the application of graphene oxide aerogel (GOA) produced from graphite through a combustion route for pre-concentrating and recovering uranium in water. The paper also demonstrates the valorisation of the spent adsorbent as an active admixture in cement to immobilise residual uranium and produce more sustainable concrete. The production method allows the bulk synthesis of GOA at 8-10 times reduced cost compared to Modified Hummer's graphene oxide (HGO). The physicochemical properties of the GOA and mechanistic details of uranium surface bindings were studied thoroughly. The GOA surface's carboxyl, hydroxyl, and epoxy groups are responsible for adsorbing uranium from water. The material showed enhanced adsorption capacity of 210 mg/g at neutral pH compared to conventional HGO (138.2 mg/g) under similar uranium concentrations. The addition of spent GOA (0.01% weight of cement) improved the compressive strength of cement mortar by 15% and arrested the leaching of residual uranium, as confirmed by the Toxicity Characteristic Leaching procedure (TCLP) test. In short, the present work addresses the critical challenges of using graphene oxide, including the cost of production and safe disposal of spent material, in preconcentrating and recovering aqueous uranium.
An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
This work demonstrates that antigalvanic reactions (AGRs) between thiol-protected plasmonic gold nanoparticles (NPs) and atomically precise silver nanoclusters (NCs) are an interfacial chemistry-driven phenomenon. We reacted 2,4-dimethylbenzenethiol (DMBT)-protected Au NPs (average diameter of 4.46 ± 0.64 nm) with atomically precise [Ag25(DMBT)18]− NC and obtained bimetallic AgAu@DMBT alloy NPs. Systematic investigations with optical absorption spectroscopy, high-resolution transmission/scanning transmission electron microscopy, and elemental mapping revealed the reaction-induced morphological and compositional transformation in NPs. Furthermore, we show that such AGRs get restricted when geometrically rigid interfaces are used. For this, we used 1,3-benzenedithiol (BDT)-protected Au@BDT NPs and [Ag29(BDT)12(TPP)4]3– NCs (TPP = triphenylphosphine). Electrospray ionization mass spectrometric (ESI MS) studies revealed that the interparticle reaction proceeds via metal–ligand and/or metal exchange, depending on the interface. Density functional theory (DFT) calculations and molecular docking simulations were used to understand the interactions and reaction energetics leading to favorable events. Interfacial chemistry of this kind might offer a one-pot synthetic strategy to create ultrafine bimetallic NP-based hybrid materials with potential optoelectronic and catalytic applications.
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