Deconvoluting electrostatic, noncovalent, and magnetic effects of iron-sulfur cofactors inside synthetic cage frameworks.

Supramolecular polymerization has entered a vibrant new stage in which precise control over self-assembly pathways enables hierarchical topologies that emulate covalent polymer systems in structure and function, while also providing access to complex organic heterostructures previously inaccessible through bottom-up self-assembly strategies. In this context, the present work delivers the first precision-designed light-harvesting supramolecular donor-acceptor double-cable polymers with orthogonal heterojunctions, constructed through a surface-catalyzed heterogeneous nucleation pathway that mirrors well-defined covalent analogues. As a proof of concept, core substituted naphthalene diimide (cNDI) chromophores bearing tripeptide side chains and diverse optoelectronic characteristics are used as modular monomers, where the peptide units simultaneously (i) exploit their chirality to regulate the balance between elongation and surface catalyzed nucleation during seeding and (ii) provide a templated interface that stabilizes a secondary cable growing in parallel on top of a primary stack. Detailed kinetic analysis, guided by spectroscopic studies and concepts adapted from surface-catalyzed protein aggregation, reveals that chirality and seeding conditions selectively channel growth through heterogeneous surface nucleation while suppressing competing pathways. This level of control further enables programmable modulation of heterojunction length through sequential seeding. Furthermore, spectral and time-resolved fluorescence microscopy of individual supramolecular double-cable heterostructures demonstrate efficient resonance energy transfer between the parallel donor and acceptor cables, establishing light-harvesting functionality at the single-chain level. Overall, this study presents a unique manifestation of hierarchical supramolecular polymerization that pushes the limits of precision and complexity in supramolecular polymers, an advance that is crucial for the continued expansion of this exciting field.

Precise 2D architectures with tailorable surface properties from organic soft materials remain a formidable scientific challenge. This work demonstrates crystallization-driven self-assembly (CDSA) as a simple yet powerful strategy to obtain discrete 2D microcrystals from biocompatible semicrystalline chromophore end-capped poly(L-lactide) (PLLA) scaffolds, serving as well-defined 2D templates for supramolecular engineering of surface properties via donor-acceptor (D-A) charge-transfer (CT) interactions. As a representative case study, we show that CDSA yields diamond-shaped 2D PLLA platelets with electron-deficient, cationic naphthalene diimide (NDI) acceptors pre-organized on the 2D surface. This enables electrostatically induced D-A interactions with anionic electron-rich dihydroxynaphthalene (DHN) guests, allowing exploration of their functional utility in piezoelectric (PE) energy harvesting. The synergistic effect of inherently non-centrosymmetric PLLA chain packing and CT-interactions on the 2D surface results in efficient macroscopic polarization switching, leading to prominent piezoelectricity (d33 ∼14 pm/V) without poling. This enhanced PE response was exploited for micropower energy harvesting as demonstrated by a piezogenerator functionality (output Voc ∼ 1.30V and Jsc ∼ 0.5µA/cm2), showing potential proof-of-concept application as an efficient physiological sensor. Multiple control experiments confirm that without such well-defined 2D architectures, PE functions do not emerge, establishing CDSA-engineered PLLA 2D platforms as emerging functional materials for energy harvesting beyond structural aesthetics.

ABSTRACT Photoelectrochemical (PEC) water splitting offers a promising solar‐driven route for hydrogen production, but its efficiency is limited by poor semiconducting properties, sluggish kinetics, and high overpotential of the oxygen evolution reaction (OER). Herein, we explored a Ru‐based coordination polymer gel (Ru‐TTN‐CPG), prepared by self‐assembly of TTN low molecular weight gelator (TTN: naphthalenediimide (NDI) core connected with four terpyridine moieties through alkyl amide chains) with Ru 2+ as a soft, processible hybrid photoanode material for PEC water oxidation. The crosslinked nanofibrous CPG promotes efficient photogenerated charge separation and transport while providing an abundant catalytic site, and the Ru‐terpyridine units enable visible‐light absorption through metal‐to‐ligand charge transfer. A type‐II heterojunction photoanode is fabricated by introducing TiO 2 as an electron‐transporting layer, which facilitates charge separation, suppresses interface recombination, and significantly improves photocurrent density. Moreover, in situ FTIR spectroscopy reveals water oxidation on the Ru‐TTN‐CPG surface under illumination, enabling identification of key intermediates. Complementary in situ XAS measurements support oxidation state changes of the Ru 2+ ‐center under operating conditions, conclusively establishing Ru 2+ as a catalytically active site. Guided by experimental observations, theoretical calculations elucidate the mechanistic pathway of water oxidation. Overall, this work highlights the potential of soft hybrid metallo‐supramolecular polymers for advancing next‐generation PEC energy‐conversion systems.

Amino acids represent versatile building blocks for the design of functional supramolecular architectures, combining inherent chirality with a rich palette of non-covalent interactions. In recent years, considerable effort has been devoted to integrating amino acid motifs into π-conjugated aromatic cores such as naphthalene diimides (NDIs), benzene-1,3,5-tricarboxamides (BTAs) and other synthetically accessible scaffolds. These systems exemplify the power of modular molecular design, where subtle variations in side chains or peptide fragments can precisely tune self-assembly pathways, supramolecular morphology and responsiveness to external stimuli. This feature article reviews the strategies and principles underlying the construction of amino acid-derived supramolecular assemblies, covering both non-covalent and dynamic covalent approaches.

Hybrid (photo)cathodes consisting of conjugated polymer and hydrogen evolution reaction (HER) cocatalysts are an emerging platform for low-cost solar fuel generation. Poly{[N,N'-bis(2-octyldodecyl)-naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]-alt-5,5'-(2,2'-bithiophene)}, known as P(NDI2OD-T2) or N2200, is a promising electron accepting material for bulk heterojunction photocathodes. Unlike inorganic (photo)electrodes, much less is known about the energetic alignment of conjugated polymer electrode/metal/electrolyte junctions. In this work, we investigate the electrical doping behavior in an N2200 cathode and its Fermi-level alignment with gold nanoparticles, which is used here as a model for the hydrogen evolution metal cocatalyst. Through UV/visible, Raman, and attenuated total-reflectance infrared spectroelectrochemistry, we observe the impact of electrical doping on the vibrational frequencies of neutral, anion, and dianion species in N2200, which suggests that electron density changes within the corresponding naphthalene-diimide (NDI) units. Upon one-electron reduction, the C═O stretching frequency of the NDI anion unit (polaron) shows a red shift by ∼ 68 cm-1. Additionally, the C═O stretching frequency of neutral units in the doped N2200 shows a minor red shift of ∼ 5 cm-1, suggesting charge transfer from neighboring polaron units. Surface-enhanced Raman spectroscopy measurements of a gold nanoparticle-functionalized N2200 electrode revealed that the Au Fermi level only shifts with that of N2200 upon polaron formation; thus, the formal potential of polymer polaron formation determines the behavior of the catalyst Fermi level, which we posit will modulate reaction capability. This mechanistic study provides a new approach for understanding the nanometer-scale energetics at the conjugated polymer/cocatalyst junction and provides critical insights for the future design of HER (photo)cathodes.

Two naphthalene diimide (NDI)-based coordination polymers (CPs), namely {[Cd(BENDI)]·DMF·H2O}n (MDJNU-25) and {[Cd(BENDI)]·DMA·H2O}n (MDJNU-26), were successfully synthesized via a solvothermal method using Cd(NO3)2·4H2O and N,N'-bis(4-ethylphenyl)-1,4,5,8-naphthalene diimide (H2BENDI) in DMF and DMA, respectively. Both CPs exhibit reversible photochromic, electrochromic, and thermochromic properties. Structural analysis reveals that the variation in solvent modulates the crystal packing, resulting in different donor-acceptor (D-A) distances between MDJNU-25 and MDJNU-26. Notably, MDJNU-26 possesses a shorter D-A distance and a faster photoresponse rate than MDJNU-25. Furthermore, both CPs exhibit obvious color changes and high sensitivity to ammonia vapor and organic amines. Fluorescence sensing reveals that elevated antibiotic concentrations enhance quenching, with tetracycline hydrochloride giving the strongest response. The quenching mechanism is attributed to the synergistic effects of the internal filter effect (IFE), fluorescence resonance energy transfer (FRET), and photoinduced electron transfer (PET). TDDFT calculations were used to explore the photochromic and antibiotic-sensing mechanisms. These CPs perform excellently in message encryption and QR code anticounterfeiting, making them promising candidates for multistimuli-responsive systems.

Owing to well-defined topologies and structural orderings, metal-organic frameworks (MOFs) can serve as a prototype platform for designing new energy materials with predesigned structures for efficient energy and electron transfer. This study explores the photoinduced electron transfer dynamics of monoanionic radicals within two different UiO-type MOFs, distinguished by their degree of interpenetration. In 0-MOF, which has relatively large pores (18.6 Å), electron transfer is primarily facilitated by solvent-assisted electron hopping, with dimethylformamide (DMF) molecules serving as bridges between naphthalenediimide (NDI)-based ligands. In contrast, the smaller pores (12.1 Å) of 100-MOF admit only one or two DMFs, favoring direct through-space electron transfer between neighboring NDI units. This comparative study highlights the role of pore size and intermolecular interactions in governing the electron transfer mechanisms within MOFs. These findings contribute to a better understanding of the photophysical properties of MOFs and open new avenues for their potential use in future energy applications.

Amyloid deposits of amyloid-β (Aβ) and hyperphosphorylated tau are pathological hallmarks of Alzheimer's disease (AD), which accounts for most dementia cases worldwide. This study investigates the effect of the complex [Ru(phen)2(pNDIp)]2+ (RuNDI; phen = 1,10-phenanthroline, pNDIp = N,N'-di(1,10-phenanthroline)-1,4,5,8-naphthalenetetracarboxylic diimide) on Aβ aggregation in vitro and in vivo. In vitro, RuNDI markedly attenuated Aβ42 aggregation, as shown by nephelometry, circular dichroism, and transmission electron microscopy, by suppressing β-sheet formation and promoting amorphous assemblies. In vivo, immunofluorescence analysis using Thioflavin-S and the 4G8 antibody in transgenic APP/PS1 mice treated with RuNDI (0.1 mg kg-1 day-1, intraperitoneally, for 10 weeks) revealed that, while RuNDI did not affect the size of existing amyloid plaques, it significantly decreased plaque density and burden in the cortex and hippocampus of treated mice. These findings suggest that RuNDI interferes with Aβ aggregation and may be further investigated for modifying plaque pathology.

Carbon-based nanomaterials with intrinsic luminescence properties have emerged as promising tools in biological and biomedical research; however, tuning their photoluminescence properties for bespoke applications remains challenging. Herein, we report the design and synthesis of a new class of pH-responsive, red-emissive carbon dot-based nanoprobes (average core size 2–5 nm) functionalised with a naphthalene diimide (NDI)-based G-quadruplex (G4) ligand. These hybrid nanoprobes combine the favourable chemical and optical properties of CDs with the high selectivity of classical molecular ligands for G4 DNA. The resulting NDI-CDs exhibit excitation-dependent emission with distinct maxima at ∼450, ∼490, and ∼590 nm upon excitation at 350, 460, and 520 nm, respectively, in contrast to the excitation-independent emission of the parent CDs (λem ≈ 450 nm). Mechanistic investigations indicate that changes in the observed emission arise primarily from covalent surface conjugation with the NDI ligand that modifies the electronic structure of the CD surface and introduces additional emissive states. Control experiments rule out significant contributions from electron transfer or aggregation effects and instead support a mechanism involving surface-state modulation and pH-dependent protonation equilibria of the NDI moiety. Importantly, the NDI-CDs retain strong G4-binding affinity (Kd = 1.38 ± 0.25 µg mL−1) and simultaneously enhance ligand bioavailability and reduce cytotoxicity. Confocal microscopy studies of live cells treated with these nanoprobes show efficient cellular uptake, preferential localisation in mitochondria and nuclei, and significantly reduced cytotoxicity relative to the free ligand, confirming their suitability for biological applications, suggesting possible engagement with intracellular G4-associated structures under physiological conditions. Overall, this work establishes a versatile and biocompatible platform for the generation of carbon-based nanomaterials for multifunctional bioimaging and nucleic acid-targeting applications.

Progress of naphthalene diimides crystalline hybrid networks in design and applications

Solvents critically influence supramolecular assembly pathways, providing a straightforward strategy to steer structural outcomes without complex synthetic modifications. Here, by regulating solvent composition and employing synchrotron-based x-ray absorption spectroscopy, we elucidate how toluene (Tol) disrupts the continuous assembly of a naphthalene diimide (NDI) derivative. In methylcyclohexane, the system follows a sequential pathway from metastable nanoparticles to nanofibers. Introducing Tol interrupts this progression, stabilizing the nanoparticles as the sole product. Oxygen K-edge X-ray absorption spectroscopy analysis indicates that Tol selectively suppresses intermolecular hydrogen bonding via π-π interactions while leaving intramolecular hydrogen bonds (HBs) intact. These insights, framed through solute-solvent π-interactions, advance the concept of "solvent engineering" for rationally programming assembly pathways and functional architectures.

The molecular structure and magnetic properties of two conjugated polymer molecules, which have the same core of naphthalene diimide (NDI) but varying alkyl side chain lengths of 2-hexyldecyl (P(NDI2HD-T2)) and 2-octyldodecyl (P(NDI2OD-T2)), are compared. Microstructural characterizations revealed that the P(NDI2HD-T2) film exhibits a shorter π-π stacking distance and more pronounced crystalline behaviors when compared to the P(NDI2OD-T2) film. In addition, the magnetically aligned P(NDI2HD-T2) film exhibited a higher degree of chain alignment compared to the P(NDI2OD-T2) film grown using the same film preparation method. The organic field-effect transistor (OFET) based on the resulting P(NDI2HD-T2) film exhibited an average electron mobility of 1.49 cm2 V−1 s−1, which is about a 13.5-fold enhancement compared to the spin-coat film. The findings of our study offer valuable insights into the process of magnetic manipulation, thereby offering guidelines for the rational selection of polymers to fabricate highly ordered films via the magnetic alignment method.

Neutral aqueous organic redox flow batteries (AORFBs) offer a promising pathway for transitioning renewables from supplementary to primary energy sources. However, their advancement is constrained by the limited long-term cycling stability and sluggish redox kinetics of materials under high-concentration conditions. Although introducing hydrophilic groups can mitigate these issues, highly symmetric molecular architectures often impose performance penalties. In this study, a series of asymmetrically modified naphthalene diimide derivatives were synthesized via a one-pot symmetry-breaking strategy, which diol-dex-NDI achieves a high solubility of 1.82M. Density functional theory and Molecular dynamics simulations reveal that diol-dex-NDI preferentially adopts a dynamic antiparallel π-π stacking mode, enhancing thermodynamic stability while effectively suppressing molecular aggregation. In situ Raman spectroscopy uncovers hydration shell dynamics during electron transfer, showing a 35% reduction in desolvation energy barrier compared to dex-NDI. Furthermore, π-π and dipole interactions with the electrode enhance adsorption energy and accelerate electron transfer. This molecular design also strengthens the key C─N bond, as evidenced by increased bond dissociation energy, thereby intrinsically improving resistance to electrochemical degradation. Leveraging these advantages, 1.0M (2M e-) diol-dex-NDI/MiAcNH-TEMPO-based AORFB delivers stable performance over 620 cycles without notable capacity decay. This work highlights the potential of symmetry-breaking molecular engineering for practical AORFB applications.

Under confinement, water changes its structure and dynamics, displaying new properties with respect to the bulk. We studied water confined in naphthalene diimide (NDI)-based molecular crystals via classical molecular dynamics simulations. We examined NDIs functionalized with either hydrophilic linear triethylene glycol side chains (NDI-TEG) or hydrophobic n-hexyl chains (NDI-C6), increasing the hydration (i.e., amount of water molecules within each crystal) up to a 1:3 NDI:water molar ratio. Static and dynamical properties of confined water are compared to those of room-temperature and supercooled (200K) bulk water, which serve as references for liquid and glassy states, respectively. The impact of confinement is analyzed through structural order parameters, time-dependent correlation functions, and hydrogen-bond (HB) analyses. At low hydration (≈1:1 NDI:water), confined water assumes a structural order that is far from the tetrahedral one, showing different spatial organizations when inserted within hydrophilic NDI-TEG or hydrophobic NDI-C6 crystals. By increasing the hydration level (≈1:3 NDI:water), the structure of confined water clusters shifts toward a more bulk-like (liquid) arrangement, while the chemical nature of the NDI side chains plays a marginal role. Notably, fast (sub-ps) and slow (hundreds of ns) water dynamics are not much influenced by the hydrophilicity/hydrophobicity of the side chains but rather by confinement effects. The analysis of the HB network autocorrelation functions highlights how finite-size effects and restricted connectivity are the main factors controlling HB dynamics. Our study paves the way toward an atomistic understanding of both structural and dynamical functions of water confined in molecular crystals, opening new paths for the rationalization of transport phenomena in the emerging class of organic mixed ionic-electronic conductors.

This work introduces five core 2,6-diaryl-substituted naphthalene diimide (NDI) derivatives accessed through Suzuki-Miyaura cross-coupling, employing imide-functionalized NDIs bearing 2-ethylhexyl side chains. The strategic incorporation of electron-donating and electron-withdrawing aryl groups at the 2,6-positions of the electron-deficient NDI core enabled systematic tuning of the electronic and optical properties of NDI derivatives. UV-Vis absorption studies showed the development of Q-bands and bathochromic shifts, depending on the electronic properties of the substituents, which are essential for optimizing optoelectronic functionality. The experimental observations were further supported by density functional theory calculations, offering deeper insight into the extent of electronic delocalization and the spatial distribution of the frontier molecular orbitals. The semiconducting behavior of all five compounds has been evaluated by fabricating them into Schottky diode devices. With different charge transport properties connected to the electronic characteristics of the core substituents, the resultant devices showed distinct structure-property correlations. Core-engineered NDIs are proven to be adaptable soft materials for tunable organic electronic applications in this study.

In this work, we discuss the complexities of Zn2+-ion storage in an organic stacked layered naphthalenediimide (NDI) via systematic experimentation and theoretical calculations. Apart from the possibility of insertion/deinsertion, NDI also provides redox-active docking motifs for Zn2+-ions. Additionally, the anode-associated challenges are mitigated using zinc phthalocyanine (ZnPc) as an organometallic protective layer. Despite achieving a high coulombic efficiency (>99%) at high cycle numbers, capacity degradation is observed during long-term cycling. The observed capacity fade is attributed to the underlying NDI's transformation from a hexagonal to a flower-like morphology. This structural evolution is attributed to the co-insertion of Zn2+ and protons from the electrode/electrolyte interface into the bulk cathode via coordination with carbonyl (─CO) and amine (─NH2) groups. Additionally, the capacity fade is attributed to the sluggish kinetics of Zn2+ stripping/plating. The ZnPc protective layer effectively guides Zn2+ deposition along the (002) crystal plane, suppresses side reactions, and enhances both the capacity retention and cycling stability of the battery. Accounting for Zn2+-ion storage in a redox-active organic host through the elucidation of key roles in phase transitions, ion diffusion dynamics, and zinc electrodeposition/dissolution processes provides a deep-dive conceptual framework for designing novel organic Zn2+-ion hosts for practical AZIBs.

This study reports an unprecedented odd-even spacer-length effect on the supramolecular polymerization and piezoelectricity of a series of amide-functionalized naphthalene-diimide (NDI) derivatives. By varying the number of methylene units (n= 1-4) in the linker between the NDI-core and the hydrogen-bonding amide group, we demonstrate that the parity of the spacer dictates the stability, internal-order, gelation, and functionality of the supramolecular polymers. Even-spacer derivatives exhibit significantly higher thermal stability, melting points, and gel-phase elasticity compared to their odd-spacer counterparts. Supramolecular polymerization for all derivatives follows a nucleation-elongation pathway; however, even-spacer monomers display markedly higher cooperativity and also favor more stable elongation. Molecular dynamics (MD) simulations elucidate the structural origin of these differences: even-spacer derivatives adopt a tightly packed helical π-stacking pattern that results in the cancellation of the in-plane dipoles. In contrast, odd-spacer derivatives form linear, offset stacking motifs where individual dipoles align and accumulate, leading to highly polarizable supramolecular polymers. This divergence in the internal dipole orientation translates into a dramatic odd-even effect on the piezoelectric dipolar hysteresis. Odd-spacer derivatives exhibit remarkably high positive piezoelectric coefficients (maximum d33 ∼ 75 pm/V), whereas even-spacer systems show much weaker, and rarely reported negative responses (minimum d33 -15 pm/V).

ABSTRACT Flexible photothermal materials made of particulate carbon, metal, polymer, or semiconductors often suffer from interfacial incompatibility, leading to cracking and delamination over prolonged use. These limitations make it difficult for flexible composite materials to simultaneously meet the requirements of long‐term interfacial stability and high photothermal performance. Here we circumvented these persistent challenges by using flexible organic crystals, where the absorber is a structurally homogeneous radical cocrystal and strong light absorption is accomplished by charge transfer (CT) between two molecular components. We cocrystallized electron donor perylene (PE) and acceptor naphthalene diimide (NDI) to prepare mechanically flexible, centimeter‐size cocrystals (PE‐NDI), which demonstrate persistent radical characteristics with a spin coherence time of 2.1 µs. Prominent donor–acceptor interaction (−87.7 kJ mol −1 ) facilitates strong light absorption from 200 to 780 nm, while hydrogen bonds are thought to account for the reversible elastic bending. Excitation at 685 nm yields an extraordinarily high photothermal conversion efficiency of 94%. Integration of PE‐NDI in a thermoelectric generator enabled direct solar energy harvesting via a photo‐thermo‐electric conversion sequence, demonstrating the potential of flexible cocrystals for renewable energy harvesting. This work highlights the untapped potential of mechanically compliant organic crystals as flexible, single‐component, lightweight photothermal materials.

Flexible photothermal materials made of particulate carbon, metal, polymer, or semiconductors often suffer from interfacial incompatibility, leading to cracking and delamination over prolonged use. These limitations make it difficult for flexible composite materials to simultaneously meet the requirements of long-term interfacial stability and high photothermal performance. Here we circumvented these persistent challenges by using flexible organic crystals, where the absorber is a structurally homogeneous radical cocrystal and strong light absorption is accomplished by charge transfer (CT) between two molecular components. We cocrystallized electron donor perylene (PE) and acceptor naphthalene diimide (NDI) to prepare mechanically flexible, centimeter-size cocrystals (PE-NDI), which demonstrate persistent radical characteristics with a spin coherence time of 2.1 µs. Prominent donor-acceptor interaction (-87.7kJ mol-1) facilitates strong light absorption from 200 to 780nm, while hydrogen bonds are thought to account for the reversible elastic bending. Excitation at 685nm yields an extraordinarily high photothermal conversion efficiency of 94%. Integration of PE-NDI in a thermoelectric generator enabled direct solar energy harvesting via a photo-thermo-electric conversion sequence, demonstrating the potential of flexible cocrystals for renewable energy harvesting. This work highlights the untapped potential of mechanically compliant organic crystals as flexible, single-component, lightweight photothermal materials.