Tridib Kumar Sarma

Amorphous coordination polymers offer distinct advantages over crystalline frameworks owing to their structural flexibility, high density of accessible coordination sites, and defect tolerance. Yet precise control over their nanoscale growth and dispersion remains a fundamental challenge. Herein, we report a biomolecule-driven supramolecular templating strategy for the generation of amorphous coordination polymer nanodot-embedded hydrogel. A guanosine monophosphate-based G-quadruplex supramolecular architecture, co-assembled with gallic acid, serves as an active template that spatially confines metal–polyphenol coordination. Upon Fe3+ incorporation, this supramolecular scaffold directs the formation of ultrasmall, uniformly dispersed coordination polymer nanodots, in contrast to the uncontrolled aggregation observed in non-templated systems. Spectroscopic and electrochemical analyses reveal that supramolecular confinement stabilizes mixed-valence Fe2+/Fe3+ species and enhances ligand-to-metal charge transfer, imparting efficient photothermal conversion under visible-light irradiation. As a proof-of-concept, the resulting hybrid material is shown to be an effective photothermal catalyst for solvent-free cycloaddition of CO2 to epoxides under ambient pressure, delivering cyclic carbonates with high efficiency. This work establishes G-quadruplex assembly as a versatile platform for regulating size-controlled growth of coordination polymers and highlights the functional advantages of biomolecular confinement for sustainable catalytic transformations.

Biomolecular condensation offers a powerful strategy to create confined microenvironments for regulating chemical transformations; however, translating this concept into minimal small‐molecule catalytic systems remains largely unexplored. Herein, we report an “all‐nucleotide” platform that spontaneously condenses into hierarchically organized G‐quadruplex (G4)‐based supramolecular networks and hydrogels with intrinsic biocatalytic activity. Co‐assembly of guanosine 5′‐monophosphate (GMP) with adenosine phosphate derivatives reveals that phosphate multiplicity and intrinsic acidity cooperatively govern hierarchical self‐assembly. While adenosine monophosphate (AMP) exhibits limited organization, adenosine di‐ and triphosphates (ADP and ATP) drive a concentration‐dependent transition from liquid‐liquid phase‐separated intermediates to fibrillar networks, with GMP as the primary structural building block. Multivalent phosphate interactions and local pH modulation regulate charge screening and proton redistribution, promoting G‐quartet stacking. ADP affords superior structural organization due to optimal alignment within a favorable pH window. At higher concentrations, both ADP‐GMP and ATP‐GMP systems form stable, self‐supporting hydrogels. These hydrogels act as efficient, metal‐free peroxidase mimics with enhanced substrate affinity compared to native horseradish peroxidase (HRP), while also serving as confined microenvironments for enzyme encapsulation, supporting multi‐step cascade reactions and sensitive biomolecule detection. This work establishes a minimalistic strategy integrating biomolecular condensation with catalysis for artificial microreactors, biocatalysis, and protocell‐inspired materials.

Small peptides exhibit remarkable antimicrobial and biological functions, yet their translation into biomaterials often requires chemical modifications that can compromise their native functionalities. Physically cross-linked hydrogels involving noncovalent interactions can retain pristine biomolecules, enabling their functional integration. Here, we present a facile strategy for constructing all-biomolecular hydrogels through the noncovalent integration of glutathione and guanosine monophosphate. The spontaneous formation of transparent, robust, and physically cross-linked hydrogels occurs via G-quadruplex assembly, preserving inherent biomolecular functionality. These hydrogels demonstrate good mechanical strength, broad pH stability, and self-healing behavior. Morphological analysis reveals protocell-like spherical intermediates, eventually yielding helical fibrillar networks. The supramolecular fibers exhibit dose-dependent cytocompatibility with selective bioactivities, suitable for biomedical applications. In vitro studies confirmed pronounced antiviral efficacy against Epstein–Barr virus and SARS-CoV-2, alongside broad-spectrum antibacterial efficacy. Additionally, the fibers induced apoptosis in gastric cancer cells. The viscoelastic and shape-sustaining behavior of these hydrogels holds potential scope to develop antimicrobial coating materials.

Guanine crystals in biogenic systems exhibit diverse optical functionalities, however, spherulitic assemblies of guanine are rarely studied. Herein, we report the formation of emissive guanine spherulites from a basic aqueous solution via a simple evaporation-induced self-assembly process.

Solvent–solute interactions play a crucial role in directing the morphological evolution of supramolecular polymers. Different noncovalent interactions, such as hydrogen bonding, hydrophobic effects, and chirality, are modulated by solvents to yield anisotropic architectures. However, the influence of composition-dependent microheterogeneity in mixed solvents on cooperative self-assembly processes and the resulting structural anisotropy remains poorly understood. Herein, we report the supramolecular self-assembly of an aggregation-induced emission-active phenylalanine derivative, l-PhePy, in MeOH–H2O mixtures of varying compositions. Notably, the solvent microheterogeneity has a pronounced influence on morphological outcomes, yielding amorphous microrods at 60% water content, crystalline fractal networks at 90%, and vesicular amorphous spheres at 95%. Mechanistic studies reveal that solvent microheterogeneity modulates noncovalent interactions, shaping both the kinetic and thermodynamic parameters of the assembled process and inducing phase segregation that confines structures at interfaces. Interestingly, under specific solvent conditions, fractal architectures emerge through a diffusion-limited aggregation pathway enabled by cooperative chiral growth, whereas rod-like and vesicular structures evolve via an isodesmic assembly pathway. These findings reveal the critical, yet often overlooked, role of microheterogeneity in mixed solvents in directing supramolecular polymerization, providing a framework for designing anisotropic supramolecular materials with emergent and optimized properties.

Peptides and proteins often assemble into one-dimensional supramolecular architectures responsible for cellular activities (e.g., actin and tubulin filaments) as well as pathological processes such as amyloid fibrillation. In many systems, such aggregation proceeds through liquid–liquid phase separation (LLPS), where the metastable coacervates act as dynamic microreactors for nucleation and growth of one-dimensional supramolecular polymers. However, how reaction conditions regulate the mechanism and kinetics of such assemblies remains unclear. Herein, we report a minimalist single-component system in which a pyreneappended arginine derivative, L-ArgPy, combine zwitterionic character with aggregationinduced emission (AIE), enabling fluorescence monitoring of its assembly. Under chargeneutral conditions, L-ArgPy self-assembles to form coacervate droplets that mediate supramolecular polymerization into tubular structures, whereas slight deviations from physiological conditions bypass the coacervate state and lead directly to one-dimensional growth. Mechanistic studies and controlled experiments reveal that cation–π interactions are responsible for the coacervate stabilization, anion–water interactions promote droplet coalescence, and π–π interactions drive polymerization via a liquid-to-solid transition. The coalescence of the membraneless coacervates is a critical step for the nucleation and growth of supramolecular polymers, as surface passivation of the coacervates inhibit the liquid to solid transition. Notably, L-ArgPy coacervates exhibit biosensing capability and antibacterial activity against both Gram-positive and Gram-negative bacteria, highlighting their potential as programmable supramolecular biomaterials.

Manipulating the coordination environment through hetero‐ligand incorporation induces controlled defects at catalytically active sites, offering a powerful route to regulate electronic structure and reactivity. Here, we present a supramolecular approach to defect engineering within a soft hydrogel matrix by confining a Bi ³⁺ ‐caffeic acid complex within a guanosine monophosphate‐based G‐quadruplex hydrogel. This confinement not only breaks local coordination symmetry and generates oxygen‐vacancy‐rich heterojunctions but also emulates the active‐site environments of enzymes. The G‐quadruplex fibrillar scaffold provides ion‐channel‐like pathways that facilitate charge transport, enhance substrate diffusion, and promote selective adsorption, while confinement ensures the uniform dispersion of catalytic sites. Together, these synergistic effects result in an exceptional N ₂ to NH ₃ conversion of 905.2 µmol h ⁻¹ g ⁻¹ _(cat) under visible light irradiation, 3.8 times higher than that of the pristine complex. This work introduces a versatile strategy that integrates defect engineering, heterojunction formation, and biomimetic confinement within a soft supramolecular assembly, establishing G‐quadruplex hydrogels as a powerful platform for sustainable photocatalytic nitrogen fixation and beyond.

Amid the global drive to eliminate carbon emissions and to mitigate the energy crisis, water splitting emerges as a beacon of innovation, converting water into clean hydrogen and oxygen. Most electrocatalysts for water splitting rely on precious metals, highlighting the demand for cost‐effective, efficient, and reproducible alternatives. Herein, we report the development of a cobalt‐adenosine monophosphate (CAH) hydrogel as a bifunctional catalyst for overall water splitting in alkaline conditions with a cell voltage of 1.56 V at 10 mA cm ⁻² , outperforming the benchmark catalytic system IrO ₂ ||Pt/C (1.62 V at 10 mA cm ⁻² ). Three crucial factors contributed to the notable water splitting of this hydrogel: (i) phosphate group in the AMP coordinated with central Co ²⁺ ions, promoting effective adsorption of key intermediates, (ii) tetrahedral arrangement around cobalt atoms making the active site more exposed and accessible, enabling better interaction with reactants and intermediates, (iii) the formation of hydrogel enhances electrolyte confinement, thus accelerating reaction kinetics. At elevated temperature, the hydrogel achieves a low cell voltage of 1.42 V at 1.0 M KOH. Even under industrially relevant harsh conditions, the hydrogel achieves 10 mA cm ⁻² at 1.53 V, underscoring its durability. This simple nucleotide‐based coordination polymer might bring significant advancement in sustainable energy conversion.