Amidst increasing environmental concerns and the limitations associated with conventional synthetic reagents, the advancement of sustainable and efficient alternatives has emerged as a significant priority in mineral processing applications. In the present study, a bio-molecule-based hydrophobic modifier was introduced as a previously unreported kaolinite collector for the froth flotation separation of kaolinite from calcite. Synthetic yttrium-loaded kaolinite (kaol-Y) was used in single mineral flotation tests, with yttrium serving as a proxy for rare earth elements (REEs). This approach aimed to assess the collector's effectiveness in ionic clay systems containing REEs. Spectroscopic techniques were used to analyze selective adsorption, while the selective aggregation of kaolinite under high shear conditions was evaluated using an image-derived particle size measuring technique, providing insights into particle aggregation under dynamic fluid environments. The impact of collector dosages on separation performance was systematically evaluated through lab-scale mechanical flotation cell experiments. The optimal dosage was determined to lie within the range of 0.2-0.4% wt, resulting in a separation process that achieved over 90% kaolinite recovery in the concentrate at a grade of 70%, starting from a feed grade of 50%. The pH-responsive nature of the collector facilitated the recovery of the reagent from the concentrate, effectively demonstrating a recycling strategy that provides a cost-effective and sustainable solution for kaolinite flotation. This approach, employing bio-inspired collectors, holds significant promise for ongoing advancements and further optimization in flotation processes.

Polyoxometalates (POMs) – molecular metal–oxide clusters composed of charged metal–oxygen polyhedra formed via solution self‐assembly processes – exhibit diverse and highly useful structure–property–reactivity relationships in the various states of matter. Found in both mineral phases and biological systems, POM motifs have played supporting roles in research areas recognized by Nobel Prizes, including structural biology and porous framework chemistry. Although their translation into real‐world technologies still requires higher levels of technological readiness, POMs are currently being explored across a wide range of interdisciplinary fields. This work builds on the collective efforts of the global POM research community, which continues to generate both fundamental insights and innovative applications. Here, we present a comprehensive survey of POM research and outline future horizons in synthesis and characterization, with particular emphasis on recent breakthroughs and emerging directions. Four thematic domains – Health, Electronics, Energy, and the Environment – are used as an organizing framework to identify key shared principles and cross‐disciplinary opportunities in POM research. The goal of this work is to consolidate international efforts, foster cross‐disciplinary collaboration, and accelerate the development of application‐ready POM materials.

Halogen···halogen interactions are a unique class of non-covalent interaction between homo or hetero halogens, arising from anisotropic electron density distributions in polarised halogens. Despite being modest in strength, they play...

Engineering the ground-state orientations of donor and acceptor groups through steric control of fluorophore conformations is an effective strategy for manipulating molecular electronics and, in turn, their emissive properties. Where strong emission is retained in the crystalline state, a correlation of structure with photophysical properties can be made, as is the case for the five pyridinium betaines reported herein. Our findings provide strong evidence that an increase in dihedral angle between N,N-diphenylamino donor and pyridinium acceptor induces a notable red-shift in emission maximum, with the mechanofluorochromic response also correlated with the same process. This research aims to address the oft-invoked explanation that planarisation induces red-shifted emission, highlighting that this effect is not universal and that systematic studies are essential. Further, this elegant steric engineering approach may be applied to other mechanochromic systems to determine the nature of their geometry changes.

Stimuli-responsive polymeric nanoparticles hold significant promise for enhancing the delivery of therapeutic agents, particularly peptides and other small biomolecules. To improve the efficiency of these drug delivery systems, accurate knowledge of their structural dynamics, disassembly process, and loading/release behavior is vital. Amongst a myriad of fluorescent probes utilized for this purpose, environmentally responsive fluorophores demonstrate distinctive advantages due to significant changes in fluorescence intensity, lifetime and/or emission wavelength with variation in their environment. In this work, we designed a series of novel multifunctional probe molecules, isoquinoline betaines (IQBs), with exquisite solvatofluorochromic properties. Through both a steady absorption signal in the visible wavelength range, and an environmentally dependent emission, these IQBs are a powerful tool for simultaneously tracking multiple key processes, including nanoparticle formation and disassembly, the loading and distribution of drug molecules, and the responsive release of drugs. This novel fluorescent probe was covalently conjugated to a pH-responsive nanoparticle and successfully probed the nanoparticle's internal structural rearrangement while also monitoring its drug-release activity of a model peptide in real-time. This IQB fluorescent probe system enhances our understanding of how nanoparticles interact with both their cargo and microenvironment and thus represents an important step forward in the development of more efficient drug delivery systems.

As part of a complex equilibria network with other chemical species, flavyliums, the chromophoric component of anthocyanins, hold great potential for use in functional polymers. This study presents the successful syntheses of polymers containing two distinct flavylium-structures, generated via post-modification of a parent polymer synthesised using reversible addition-fragmentation chain transfer (RAFT) polymerisation. The selective modification of acetophenone moieties enabled precise tuning of the polymers' properties, which are strongly influenced by the markedly different chemical characteristics of flavyliums and the other species in equilibria with them. The synthesised flavylium-containing polymers exhibit multi-stimuli responsiveness to variations in solvent, pH, light, and temperature, thereby introducing intricacy and viable functionality to the polymer system. The surface activity and critical aggregation concentrations (CAC) of the synthesised polymers were studied using profile analysis tensiometry (PAT), revealing distinct aggregation and self-assembly behaviours. Fractal-like aggregates formed by the flavylium-containing polymers were investigated using cryogenic electron microscopy (Cryo-EM) and small-angle X-ray scattering (SAXS). This research bridges the colourful dynamic equilibria of flavylium chemistry with polymer chemistry, paving the pathway for further investigations into flavylium-polymer interactions and the development of tuneable material properties of responsive polymers.

This study successfully synthesised flavylium-containing polymers via RAFT polymerisation and post-modification, demonstrating tuneable multi-stimuli-responsiveness to pH, light, temperature and solvent.

With increasing environmental concerns and the drawbacks associated with the synthetic materials currently used in industry, there is a growing demand for more eco-friendly and efficient alternatives in mineral processing applications. To help address this, three bioinspired surfactants (M8Flav, M12Flav, and D8Flav) were synthesized by modifying the core structure of flavylium, a plant-based pigment, by installing secondary and tertiary alkyl amines. Hydrophobic agglomeration of fine kaolinite (D 4,3: 10 mu m) particles facilitated through the application of these bioinspired surfactants was examined. Spectroscopic, microscopic, and XRD (X-ray diffraction) analyses were performed to interrogate the association of flavylium with kaolinite including the elucidation of potential interactions and mechanisms for the changes in macroscopic properties of the kaolinite aggregates. The surface hydrophobicity of kaolinite was evaluated using the Washburn capillary rise method, with enhanced hydrophobicity observed after treatment with the surfactants. Real-time in situ aggregate size measurements under a controlled shear rate were conducted using an image-derived particle size measuring technique to systematically evaluate the impact of surfactant dosage and alkyl chain configuration on aggregate size and stability. Turbidity reduction of the supernatants and gravitational sedimentation under quiescent conditions of surfactant-treated kaolinite slurries were also examined. These findings reveal the applicability of flavylium-based surfactants, positioning them as valuable tools for improving techniques in clay separation and dewatering processes.

The effective separation of chalcopyrite, an extensively utilized copper mineral, presents a considerable hurdle for the mineral processing sector due to its geological tendency to be colocated with various sulfide minerals and its intricate surface chemistry that hinders efficient separation using conventional approaches. This research aims to address this challenge by utilizing Reversible Addition-Fragmentation Chain Transfer polymerization (RAFT) as a synthetic methodology for preparation of collector/flocculants to enhance the efficiency and selectivity of reagents for utilization in chalcopyrite flotation/flocculation. A RAFT polymer, poly(CA(4)-co-ACOEA(14)), was synthesized incorporating O-ethyl acetylcarbamothioate (R-O-C(& boxH;S)-NH-C(& boxH;O)-CH3) functionality for selective binding and cardanyl acrylate moiety as a hydrophobic component, with the goal of selective separation of chalcopyrite from pyrite. Laboratory experiments encompassing flotation/flocculation tests, adsorption assessments, and analyses utilizing UV spectroscopy, FTIR spectroscopy, X-ray photoelectron spectroscopy, and contact angle measurements were conducted to explore its performance in froth flotation and elucidate its adsorption mechanism on both mineral surfaces. A comparative study between poly(CA(4)-co-ACOEA(14)) and poly(CA(4)-co-XEA(14)), the latter is a polymer of similar molecular weight and hydrophobicity containing the xanthate functionality, demonstrated that poly(CA(4)-co-ACOEA(14)) exhibits superior performance. This enhanced efficacy could be attributed to the polymer's capacity to selectively adhere to the chalcopyrite surface, rendering it hydrophobic, while a comparable effect is not observed on pyrite due to weak adsorption. Furthermore, the flocculation performance of poly(CA(4)-co-ACOEA(14)) showcases its dual functionality as both a collector and a flocculant.

Flavyliums are abundant naturally occurring, stimuli-responsive cationic chromophores found in anthocyanins that constitute the majority of red and blue pigments found in flora. While synthetic molecular derivatives have been devised to fine-tune these characteristics, the development of polymeric materials in this regard remains scarce. To address this, a flavylium-based methacrylamide derivative (FlavM-A1) was successfully synthesized, but its radical polymerization proved to be ineffective. To overcome this constraint, a convergent synthetic route for a series of flavylium-containing polymers was developed, employing reversible addition-fragmentation chain transfer (RAFT) polymerization followed by postmodification to install the flavylium chromophore. The flavylium-containing polymers described in this work exhibit improved hydrolytic stability in their flavylium moieties compared to the small-molecule FlavM-A1 while both possess interesting stimuli responsiveness and surfactant-like properties.

Responsive nanomaterials have emerged as promising candidates for advanced drug delivery systems (DDSs), offering the potential to precisely target disease sites and enhance treatment efficacy. To fulfil their potential, such materials need to be engineered to respond to specific variations in biological conditions. In this work, we present a series of pH/redox dual-responsive hybrid nanoparticles featuring an amphiphilic shell polymer and a pH-responsive core polymer. These nanoparticles incorporate a polyoxometalate (POM), specifically the cobalt(iii)-substituted borotungstate ([BIIIW11O39CoIII]6-), loaded through coordination chemistry between the encapsulated CoIII ions of the POM and pyridyl functional groups on the core polymer. The resulting hybrid nanoparticles show potential for controlled release with excellent stability at physiological pH, and efficient particle disassembly in response to the combination of pH and redox stimuli. Disassembly is proposed to occur following a two step mechanism. Structural rearrangement of the nanoparticle occurs on acidification followed by destabilization of the coordination bond between the polyanion and the pyridyl functionality in the core polymer following reduction. In this system, the POM acts in a novel role as a redox active structural cross-linker. These hybrid dual-responsive nanoparticles, featuring superior colloidal stability under extracellular conditions and controllable disintegration in response to the dual stimuli of acidic pH and redox conditions, provide a novel platform for the controlled intracellular release of therapeutics.

The process for selective separation of chalcopyrite, a widely used copper mineral, is a major challenge for the mineral processing industry due to its natural occurrence of various sulphide minerals and its complex surface chemistry. This research focused on novel collector chemistry to improve the efficiency and selectivity of chalcopyrite flotation. A novel collector, namely, 3-pentadecylphenyl 4-(3,3-diethylthiouredo-4-oxobutanoate) (DP089), consisting of acylthiourea group was synthesized using cardanol as starting material, to selectively separate chalcopyrite from pyrite. The performance of DP089 in froth flotation and its adsorption mechanism on chalcopyrite and pyrite are investigated in laboratory experiments such as flotation and adsorption tests, as well as analyses using UV spectroscopy, FTIR spectroscopy and contact angle measurements. Comparing the performance of DP089 with the conventional collector potassium amyl xanthate (PAX), it is clear that DP089 exhibits stronger collecting ability and remarkable selectivity for chalcopyrite over pyrite. This could be due to the ability of DP089 to selectively attach to chalcopyrite surfaces, making it hydrophobic, while the same effect is not observed on pyrite surfaces due to the weak adsorption of DP089. Experimental data on the binding mechanism show that DP089 chemically adsorbs on the chalcopyrite surface by interacting with copper ions. This leads to the formation of unique structures of C-O-Cu and C-S-Cu.

Stimuli-responsive nanoparticles have garnered significant interest for advanced materials design and development in areas such as biomedicine, sensing, and energy. Recent studies have demonstrated that integrating multiple functionalities into a single nanoparticle structure is a crucial approach for engineering multi-responsive properties. In this study, light- and redox-responsive nanoparticles were synthesized using a simple one-pot emulsion polymerization utilizing mild thiol-disulfide exchange reactions to direct the self-assembly process. Poly(disulfide) bonds were formed during this process and comprised the core part of the nanoparticles, enabling redox responsiveness upon disulfide cleavage. A photochromic diarylethene (DAE) was also covalently attached within the hydrophobic poly(disulfide) matrix, imparting light-responsive behavior to the particles. Tuning the nanoparticle composition by varying the thiol/DAE ratio enabled a correlation between particle composition and disassembly kinetics to be established. The DAE retained photochromic activity in the nanoparticles, however, the switching efficiency was diminished when compared to the monomer due to the matrix effect. Light- and redox-responsive nanoparticles were synthesized using a simple one-pot emulsion polymerization utilizing mild thiol-disulfide exchange reactions to direct the self-assembly process.

A reversible change in a material's fluorescence spectrum on the application of force is known as mechanofluorochromism (MFC) and is a well-established field of study. However, the mechanism(s) responsible for the chromism may be different for each new material and it is important to elucidate these for many reasons, including the rational design of new analogues with targeted properties. Herein, the photophysical properties and mechanistic understanding of two MFC pyridinium betaines are reported. The emission sensitivity is explained by the coexistence of crystalline and amorphous phases after the application of mechanical force, with increased conformational flexibility in the amorphous phase facilitating red-shifts in emission. This explanation is supported by evidence from a range of spectroscopic techniques, including electron diffraction (ED) and fluorescence lifetime imaging microscopy (FLIM) mapping, two techniques that have, to the best of our knowledge, not been applied in the field of MFC to mechanically ground particles. For one of the compounds, ED on ground microcrystallites shows unambiguously that the same crystalline phase is retained after grinding, along with an amorphous contribution, providing direct evidence for the crystalline-amorphous mechanism, and the presence of these two phases is further supported by FLIM mapping. We envision these techniques will be highly instructive for the analysis of similar materials.

A boron trifluoride–pyridyl Lewis adduct is reported, which exhibits various types of chromism and high solid-state photoluminescence quantum yields, as well as excitation-dependent emission in the mechanically ground form.

Research on polyoxometalates (POMs) with the Keggin structure has been ongoing for several decades. However, the trilacunary phosphomolybdate derivative was difficult to obtain until recently. By using pyridine in nonaqueous media, stabilization of the trilacunary phosphomolybdate was achieved, and the six terminal ligand sites within the structural vacancy alternated between oxido and pyridyl ligands. Through ligand exchange experiments, we were able to control the intramolecular spatial separation of coordinated halogenated ligands as well as intermolecular halogen-halogen interactions in the crystalline state. Our results reveal a new X-6 synthon (where X = Cl, Br, and I) and a desolvation-induced single-crystal to single-crystal transition.

Polyoxometalates (POMs) are anionic molecular metal oxides with expansive diversity in terms of their composition, structure, nuclearity and charge. Within this vast collection of compounds are dominant structural motifs (POM platforms), that are amenable to significant chemical tuning with minimal perturbation of the inorganic oxide molecular structure. Consequently, this enables the systematic investigation of these compounds as inorganic additives within materials whereby structure and charge can be tuned independently i.e. [PW12O40](3-)vs. [SiW12O40](4-) while also investigating the impact of varying the charge balancing cations on self-assembly. The rich surface chemistry of POMs also supports their functionalisation by organic components to yield so-called inorganic-organic hybrids which will be the key focus of this perspective. We will introduce the modifications possible for each POM platform, as well as discussing the range of nanoparticles, microparticles and surfaces that have been developed using both surfactant and polymer building blocks. We will also illustrate important examples of POM-hybrids alongside their potential utility in applications such as imaging, therapeutic delivery and energy storage.

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.