Abstract The construction of helical architectures from achiral building blocks remains a fundamental challenge in supramolecular and materials chemistry. We report the first triple-helical cluster-assembled material constructed entirely from achiral components via covalent coordination. Thiol-protected Ag12 nanoclusters are linked by a rigid 4,4′-bipyridine ligand to form a three-dimensional framework with a unique triple-helical topology. Structural analysis shows that the helicity arises solely from the spatial arrangement of cluster nodes and linkers, without chiral precursors or templates. The material exhibits p-type semiconducting behavior with a conductivity of ∼10–6 S/cm and hole mobility of ∼1.7 cm2/(V s), highlighting its potential for electronic and optoelectronic applications.

The stability of the copper nanocluster has always been a concern owing to its low half-cell reduction potential. It is well documented that anion templates are known to tune the structure and impart stability to the nanocluster. Here, using a simple reduction strategy, we have obtained a dihalide-templated copper nanocluster for the first time. The copper cluster, namely, [Cu23(μ3-Cl)2(SPh-CF3)18(PPh3)6(CF3COO)3], features a unique double triangular prismatic structure. The structure contained a basic unit with the formula of Cu9(μ3-Cl)2 forming an inner triangular prism, which is further wrapped by a second triangular prism with the formula Cu12(SPh-CF3)18(PPh3)6(CF3COO)3, forming a unique twisted triangular double prismatic geometry. Further, we have proposed a plausible growth mechanism that helps us decipher the evolution of the cluster, and here we observed a peculiar “twisted concentric growth” of the two prisms, which occurs due to the radial dimerization of the Cu11 base prism to form the dimeric Cu23 cluster. The unique growth pattern and structure influence the electronic states of the cluster, as evidenced by experimental and theoretical studies, thereby imparting the material with good photoresponse properties. The new insights into this novel dihalogen templated twisted double prismatic copper cluster may pave the way to understanding the unique structural growth and developing photonic materials.

ABSTRACT The increasing prevalence of fungal phytopathogens and the widespread emergence of fungicide resistance necessitate the development of alternative antifungal strategies with reduced environmental impact. Here, we report the isolation and characterization of a novel antifungal metabolite, SM06, produced by the rice seed-associated endophytic bacterium Phytobacter sp. RSE02. SM06 exhibited broad-spectrum antifungal activity against plant and human pathogenic fungi, including Curvularia lunata, Fusarium oxysporum, and Candida albicans. In vitro assays and micromorphological analyses revealed that SM06, an indole dimer, disrupts fungal cell membrane integrity, while in planta experiments demonstrated significant suppression of brown leaf spot disease in tomato and rice. Molecular docking suggested that SM06 binds to lanosterol 14α-demethylase (ERG11), a key enzyme in fungal sterol biosynthesis. Consistent with this prediction, LC-MS–based analyses confirmed a significant reduction in ergosterol content in SM06-treated fungal cells. Together, these findings identify SM06 as a biologically active antifungal metabolite produced by a plant-associated bacterium, highlighting its potential application in sustainable fungal disease management.IMPORTANCEFungal diseases cause major losses in crop production and contribute to the growing challenge of antifungal resistance, underscoring the need for sustainable alternatives to chemical fungicides. This study identifies SM06, a novel indole dimer produced by the rice seed endophyte Phytobacter sp. RSE02, with strong antifungal activity against economically important plant pathogens and clinically relevant fungi. Through integrated chemical, cellular, and in planta analyses, we demonstrate that SM06 disrupts fungal membrane integrity by inhibiting ergosterol biosynthesis. The compound is biocompatible, stable, and effective in plant disease suppression, highlighting its translational potential for crop protection. These findings reveal seed endophytes as an important yet underexplored source of antifungal metabolites and provide a mechanistic foundation for developing eco-friendly biocontrol strategies with implications beyond agriculture.

Serotonin, widely recognized as a mammalian pineal hormone, is also present in plants, yet its in vivo dynamics and physiological roles remain poorly understood due to the absence of real-time sensing tools. Herein, we report nitrogen-doped carbon quantum dot (N-CQD) nanosensors (∼5 nm; quantum yield 36%) for the selective detection and visualization of serotonin in plant systems. The sensing mechanism involves static-dominated mixed fluorescence quenching accompanied by a blue shift, corroborated by UV-Vis spectral changes, Stern-Volmer analysis, and fluorescence lifetime decay. The nanosensor exhibits a low detection limit of 0.391 µM and a linear response range of 4.74-75 µM. Using Arachis hypogaea seedlings as a model, stronger and more consistent serotonin-dependent fluorescence responses were observed compared with those in other plant species, enabling reliable in vivo monitoring. Real-time sensing revealed a condition-dependent regulatory role for serotonin, including growth inhibition under non-stress conditions and growth enhancement under stress, indicating a dual function in stress adaptation. Fluorescence microscopy further confirmed the intracellular association of serotonin with N-CQDs, providing direct visual evidence of its localization. This work establishes a nanosensor-based platform for real-time detection of serotonin in plants and advances understanding of serotonin-mediated signalling in plant growth and stress responses.

The selective acetic acid formation by Ag@NU-1000-SH under white light without the use of sacrificial agents.

Metal nanoclusters (MNCs) are an emerging class of atomically precise nanomaterials with sizes comparable to the Fermi wavelength of free electrons, exhibiting discrete energy levels, molecular-like behaviors, and tunable physicochemical properties. Among these properties, photothermal conversion-the process of transforming absorbed light into thermal energy-has garnered considerable interest due to its vital importance in applications such as solar energy harvesting, photothermal therapy, and catalysis. This review begins by summarizing recent progress in synthetic strategies for MNCs, including kinetic control, seeded growth, in situ two-phase ligand exchange, and metal exchange, which help overcome challenges such as polydispersity, low yield, restricted surface functionality, and lengthy synthesis times. Subsequently, a comprehensive analysis is provided on the photothermal conversion behaviors of various MNC systems (e.g., coinage metal nanoclusters, Ti NCs, and Mo NCs) reported in the past five years, with in-depth discussion of their structural characteristics, absorption properties, photothermal conversion efficiencies, and underlying conversion mechanisms. Finally, the review addresses current challenges and prospects for advancing MNC-based photothermal technologies via atomic-level engineering and interdisciplinary approaches. Through this in-depth and systematic review, we endeavor to provide scholars dedicated to metal nanocluster research-as well as experts engaged in photothermal conversion and its diverse applications-with valuable scientific insights. We are confident that this contribution will not only catalyze innovative breakthroughs but also unlock exciting new frontiers within this vibrant and rapidly evolving field of study.

The stability of the copper nanocluster has always been a concern owing to its low half-cell reduction potential. It is well documented that anion templates are known to tune the structure and impart stability to the nanocluster. Here, using a simple reduction strategy, we have obtained a dihalide-templated copper nanocluster for the first time. The copper cluster, namely, [Cu23(3-Cl)2(SPh-CF3)18(PPh3)6(CF3COO)3], features a unique double triangular prismatic structure. The structure contained a basic unit with the formula of Cu9(3-Cl)2 forming an inner triangular prism, which is further wrapped by a second triangular prism with the formula Cu12(SPh-CF3)18(PPh3)6(CF3COO)3, forming a unique twisted triangular double prismatic geometry. Further, we have proposed a plausible growth mechanism that helps us decipher the evolution of the cluster, and here we observed a peculiar “twisted concentric growth” of the two prisms, which occurs due to the radial dimerization of the Cu11 base prism to form the dimeric Cu23 cluster. The unique growth pattern and structure influence the electronic states of the cluster, as evidenced by experimental and theoretical studies, thereby imparting the material with good photoresponse properties. The new insights into this novel dihalogen templated twisted double prismatic copper cluster may pave the way to understanding the unique structural growth and developing photonic materials.

Limiting the action of antimicrobials by employing photoswitchable antibiotics holds immense potential to combat the emergence of antimicrobial resistance. These photoswitchable antibiotics are expected to be less/nontoxic in their thermally stable states than the light-induced metastable forms, such that after treatment with the active isomer, the drug toxicity will be automatically reduced or drastically lost after excretion from human and animal bodies into the environment. However, the design of such light-sensitive antibiotics has proven to be very challenging. Most of the previously reported azo-based ciprofloxacin derivatives exhibited diminished potency with the light-induced cis state. Herein, we present the design and synthesis of azoheteroarene-ciprofloxacin conjugates, which exhibited higher antimicrobial potency by the cis-isomer than the trans-isomer against Gram-positive and Gram-negative pathogens. The potency was tuned by varying molecular design. All conjugates displayed a high degree of bidirectional photoisomerization, long cis half-lives, and impressive photofatigue resistance. Notably, the conjugate AAP-2-Cip carrying a flexible linker and pyrazole at the exterior of arylazopyrazole furnished the highest activity difference of 2.5-fold between two isomers, and the cis isomer of ABP-Cip showed 1.7-fold increased potency than ciprofloxacin. Docking studies revealed different binding affinities for two isomers with the DNA gyrase. The molecular design concept unfolded herein may be applied to other antibiotics to transform them into potent photoswitchable antibiotics for suppressing the growth of antibiotic-resistant pathogens.

L-Glutamate is the primary excitatory neurotransmitter in the central nervous system, and its dysregulation is associated with numerous neurological disorders, underscoring the importance of sensitive, real-time detection in living organisms. In this study, we created a biocompatible fluorescent nanosensor using a nitrogen-doped carbon quantum dot aluminium ion composite (N-CQDs/Al) to selectively detect L-glutamate through a straightforward fluorescence "off-on" process. The N-CQDs and the complex were thoroughly analysed with DLS, TEM, FT-IR, EDX, UV-Vis, and fluorescence spectroscopy, confirming their size, surface features, and optical stability. When coordinated with Al3+, fluorescence was quenched, but the addition of L-glutamate revived it via competitive binding. The sensor exhibited high sensitivity, a detection limit of 0.14 µM, a wide linear range, and excellent selectivity toward common amino acids and interfering substances. Its low toxicity and robust photostability allowed for real-time in vivo monitoring of endogenous glutamate and in vitro testing in the optic tectum and retina of live zebrafish. To our knowledge, this is the first report of an N-CQDs/Al3+ based fluorescence "off-on" system for real-time, in vivo glutamate detection, offering a simple and efficient platform for neurotransmitter sensing and neurobiological research.

The extensive use of neonicotinoid pesticides has greatly enhanced crop yields. However, their water solubility, environmental persistence, and toxicity to nontarget species raise ecological and health concerns. In this research, we present nitrogen-doped carbon quantum dots (N-CQDs) approximately 6 nm in size that serve as a multifunctional platform. They can detect neonicotinoid pesticides through a simple fluorescence turn-off method, diminish their effectiveness in water and agricultural settings, and act as nanopesticide repellents. The N-CQDs exhibit strong, stable fluorescence, numerous surface functional groups, and high biocompatibility, enabling selective interactions with compounds such as imidacloprid, thiamethoxam, clothianidin, thiacloprid, and nicotine. Characterization techniques such as TEM, PXRD, FT-IR, XPS, EDX, UV-vis, 1H NMR, and fluorescence spectroscopy were used to analyze the nanosensor's morphology and features. The sensor achieved a detection limit of 23 nM, indicating excellent sensitivity. Spectroscopic analyses indicate that N-CQDs form strong noncovalent associations and stable complexes with neonicotinoid pesticides, accompanied by a noticeable decrease in their biological activity as observed in functional experiments. Practical tests, including cytotoxicity assays, fruit bioassays, and ant-repellence trials, confirm that N-CQDs can effectively neutralize neonicotinoid pesticides in real-world conditions without being toxic or unsafe. This approach offers a sustainable way to address neonicotinoid pesticide pollution, promoting safer farming methods and environmental preservation. Surprisingly, the nanosensor not only detects and mitigates neonicotinoid pesticides but also serves as a nanopest repellent in real-world agricultural use.

Ligand engineering has emerged as an impressive strategy for modulating the optical properties of atomically precise nanoclusters that exhibit molecule-like behavior. Establishing systematic correlations between well-defined structures and their corresponding properties remains a critical challenge in this field. In this study, we compare the crystal structures and photoluminescence characteristics of a pair of alkyne-functionalized Ag3 nanoclusters differentiated by their electronic and steric factors. The clusters bearing aromatic alkyne ligands exhibit predominantly ligand-centered emission, whereas those stabilized by aliphatic alkyne ligands display metal-centered emission. Based on these observations, we elucidate the distinct origins of photoluminescence by correlating structural distortions with the resulting photoluminescence properties.

Two-dimensional (2D) cluster-assembled materials are unique due to their exceptional optoelectronic and photoluminescence properties. The design and synthesis of 2D materials, where clusters serve as nodes interconnected by conjugated linkers, could significantly enhance the coupling between the nodes, thereby facilitating efficient charge transfer. We have synthesized a novel 2D alkynyl-ligand protected cluster assembled material (CAM) consisting of two distinct types of Ag14 nodes, which are interconnected by pyrazine molecules to form the overall architecture. The presence of two different geometries within the same CAM structure is a rare observation. The formation of this structure could be attributed to the specific bonding interaction between the acetylene ligand and the silver ions. Combined experimental and theoretical calculations revealed that electronic excitation is primarily driven by mixed transition characters. These include π → π* transitions, where electron transfer occurs from occupied C-p orbitals to the vacant π* orbitals of the alkynyl carbon or pyridyl nitrogen atoms, as well as LMCT (Ligand-to-Metal Charge Transfer) transitions mixed with cluster-centred states.

Atom-precise metal nanoclusters (NCs) have garnered considerable attention due to their photoluminescence and catalytic properties arising from the quantum confinement effect and metal-ligand interaction. However, the tendency of NCs to aggregate under reaction conditions hinders their catalytic activity. Surface-protecting ligands can enhance the stability, but they often reduce surface exposure and, consequently, catalytic activity. The incorporation of surface-cleaned clusters into the pores of metal-organic framework (MOF) is highly desirable. Here, we constructed a hybrid structure in which Zr-based MOF, UiO-66-NH2, is grown directly on the surface of the [Au9(PPh3)8](NO3)3 cluster. During the nanocluster-templated growth of MOF, the triphenylphosphine ligand was removed, yielding a surface-clean gold cluster-MOF composite material. An integrated experimental-theoretical analysis revealed that the ligand-free Au clusters occupy the pores of the MOF framework. This composite exhibited an overpotential of 65 mV and demonstrated a high chronopotentiometric stability in the hydrogen evolution reaction (HER). For the horseradish peroxidase (HRP)-mimicking reaction, the Michaelis-Menten constants (Km) for H2O2 and TMB were determined to be 0.1 and 2.7 mm, respectively. Experimental and computational studies demonstrated that the MOF-induced confinement, coupled with NH2 group interactions within its pores, modulates catalyst-substrate interactions, thereby improving the catalytic performance and stability of the composite.

The bacterial-blight and fungal-blast disease in rice, caused by Xanthomonas oryzae and Magnaporthe oryzae, are the leading causes of rice production loss globally. Excessive reliance on chemical fertilizers and pesticides in agriculture contributes to environmental toxicity; alternatives, like nanoparticles, are safer for plant growth enhancement and disease management. This study focuses on the synthesis of biogenic silver nanoparticles (AgNPs) using beneficial rice-seed endophytic bacterium. Scanning and transmission electron microscopy revealed the spherical nature of the AgNPs with a size range of 10-20 nm. Energy-dispersive X-ray spectroscopy of the AgNPs confirmed the presence of elemental silver, validating the synthesis mechanism. The impact of these biogenic AgNPs on rice growth was investigated through controlled experiments, demonstrating significant enhancement in seed germination and seedling growth of up to 50%. The AgNPs exhibited promising antimicrobial activity against bacterial and fungal pathogens. It has been found that AgNPs can be taken up through rice roots and transported to leaves and shoots. The results further suggest that AgNP treatment induces variable changes in the expression of immunity-related genes in rice. While genes like Oscul3a were downregulated, OsWRKY31 was strongly upregulated, indicating a complex response that could involve both suppression and activation of immune pathways. Both in vitro and in vivo assays revealed substantial antibiosis against Xanthomonas and Magnaporthe, emphasizing their potential as a natural alternative to synthetic antimicrobials. The results highlight their dual functionality in enhancing crop growth and serving as an environmentally friendly solution for controlling agricultural pathogens.

Correction for 'A thiolated copper-hydride nanocluster with chloride bridging as a catalyst for carbonylative C-N coupling of aryl amines under mild conditions: a combined experimental and theoretical study' by Anish Kumar Das et al., Nanoscale, 2024, 16, 3583-3590, https://doi.org/10.1039/D3NR05912J.

Ligand engineering has emerged as an impressive strategy for modulating the optical properties of atomically precise nanoclusters that exhibit molecule-like behavior. Establishing systematic correlations between well-defined structures and their corresponding properties remains a critical challenge in this field. In this study, we compare the crystal structures and photoluminescence characteristics of a pair of alkyne-functionalized Ag3 nanoclusters differentiated by their electronic and steric factors. The clusters bearing aromatic alkyne ligands exhibit predominantly ligand-centered emission, whereas those stabilized by aliphatic alkyne ligands display metal-centered emission. Based on these observations, we elucidate the distinct origins of photoluminescence by correlating structural distortions with the resulting photoluminescence properties.

Pseudomonas aeruginosa is a highly virulent Gram-negative pathogen that exhibits multiple mechanisms of antibiotic resistance, including resistance to colistin, a last-resort therapeutic agent, posing a significant clinical challenge. Recently designated by the World Health Organization (WHO) as a high-priority pathogen, P. aeruginosa underscores the urgent need for novel therapeutic strategies. In this study, we explored the potential of combination therapy, specifically investigating the synergistic interaction between colistin and nitroxoline, a hydroxyquinoline derivative, against a highly colistin-resistant P. aeruginosa strain.Bacterial viability was assessed through growth curve analysis, and the mechanistic basis of the observed synergy was examined using membrane permeability assays, intracellular reactive oxygen species (ROS) quantification, and gene expression profiling via quantitative real-time PCR (qRT-PCR). Additionally, the impact of this combination on bacterial survival was evaluated by analyzing its effects on biofilm formation and persister cell development under antimicrobial stress, both critical contributors to chronic and treatment-refractory infections in humans.Our results demonstrate that nitroxoline potentiates the bactericidal activity of colistin by enhancing membrane permeability, leading to significant inhibition of planktonic growth and pronounced efficacy against structured microbial communities such as biofilms and persister cells. Furthermore, the combination therapy completely suppressed bacterial motility, a critical virulence trait that facilitates immune evasion.These findings present a compelling therapeutic strategy to combat antibiotic resistance in Gram-negative pathogens, including both wild-type and drug-resistant clinical isolates of P. aeruginosa and Acinetobacter baumannii. The study highlights the significant potential of the colistin–nitroxoline combination to mitigate colistin resistance and reduce the global burden of multidrug-resistant infections.

Atom-precise metal nanoclusters have emerged as a class of materials with unique structural and electronic properties, driven by quantum size effects and precise atomic arrangements. This review delves into recent advancements in the field, focusing on key aspects, such as ligand exchange reactions, structural characterization and catalytic properties of copper nanoclusters (NCs), development of silver cluster-assembled materials with enhanced stability and properties, and stabilization of NCs in metal–organic frameworks (MOFs). Synthesis of specific clusters for desired applications can be attained through ligand exchange transformation reaction. Among the coinage metal ions, the research on copper NCs is less explored due to low redox potential. Still, there are some reports with unique structural architecture that exhibit catalytic properties. Stability and properties of clusters can be enhanced by linking the cluster to higher dimensional or embedded into the porous MOF structures. This review discusses some of the recent advancements achieved in the field of nanoclusters and their assemblies, ranging from fundamental studies to structure-property correlation and applications.

Silver nanocluster assemblies are an emerging class of fluorescent and stable solid materials by virtue of their structural tunability and stability compared to isolated clusters. The photophysical properties of the cluster nodes are influenced by an intra- or intercluster interaction. In this work, we show two-dimensional (2D) [Ag5(C2tBu)2(CF3COO)3(C4H4N2)](CHCl3) and three-dimensional (3D) [Ag4(C2tBu)(CF3COO)3(C4H4N2)] silver nanocluster assemblies obtained by tuning the molar ratios of the same protecting ligands and linker. The 2D assembly possesses a one-dimensional (1D) chain held together through the Ag···Ag interactions, whereas in the 3D assembly, Ag4 units are linked through trifluoroacetate ligands to form the 1D chain with Ag4-O-Ag4 and Ag4-O-C-O-Ag4 connectivity. This varying effect of argentophilic interaction influences photoluminescence properties. In the 2D assembly, the emission was found to be dominated by the cluster-centered state owning to enhanced argentophilic interactions, whereas in 3D, the emission is from the linker. The theoretical investigations also revealed that the lowest unoccupied molecular orbitals (LUMOs) of the 3D assembly are localized on the pyrazine linker. In contrast, the LUMOs of the 2D assembly are mostly localized on the metal atoms within the cluster. This work highlights not only the importance of synthesis but also emphasizes the understanding of the cluster structure-luminescence relationship.