Herein, we report the rich morphological and conformational versatility of ab iologically active peptide (PEP-1), whichf ollows diverse self-assembly pathwayst o form up to six distinct nanostructures and up to four different secondary structures through subtle modulation in pH, concentration and temperature. PEP-1 forms twisted b-sheet secondary structures and nanofibers at pH 7.4, which transform into fractal-like structures with strong b-sheet conformations at pH 13.0 or short disorganized elliptical aggregates at pH 5.5. Upon dilution at pH 7.4, the nanofibers with twisted bsheet secondary structural elements convert into nanoparticles with random coil conformations.I nterestingly,t hese two selfassembled states at pH 7.4 and room temperature are kinetically controlled and undergo af urther transformation into thermodynamically stable states upon thermal annealing: whereas the twisted b-sheet structures and corresponding nanofibers transform into 2D sheets with well-defined b-sheet domains,the nanoparticles with random coil structures convert into short nanorods with a-helix conformations.N otably, PEP-1 also showed high biocompatibility,l ow hemolytic activity and marked antibacterial activity,rendering our system apromising candidate for multiple bio-applications.

This article reports H-bonding driven supramolecular polymerization of naphthalimide(A)-thiophene(D)-naphthalimide(A) (ADnA, n = 1-4) conjugated ambipolar π-systems and its remarkable impact on the room temperature ferroelectricity. Electrochemical studies confirm the ambipolar...

Two-dimensional (2D)-supramolecular assemblies of π-conjugated chromophores are relatively less common compared to a large number of recent examples on their low dimensional (0D or 1D) assemblies or 3D architectures. This article reports a rational design for the 2D supramolecular assembly of an amphiphilic core-substituted naphthalene-diimide derivative (cNDI-1). The building block contains a naphthalene-diimide (NDI) chromophore, symmetrically substituted with two dodecyl chains from the aromatic core while the imide positions are functionalized with two hydrophilic wedges containing oligo-oxyethylene chains. In water, it exhibits entropically favorable self-assembly with a critical aggregation concentration of 1.5 × 10 −5 M and a lower critical solution temperature of 55 °C. The UV/vis absorption spectrum in water shows bathochromically shifted absorption bands compared to that of the monomeric dye in THF, indicating offset π-stacking among the NDI chromophores. C−H symmetric and asymmetric stretching frequencies in the FT-IR spectrum support the presence of organized hydrocarbon chains in trans conformation in the self-assembled state, similar to that in the crystalline n-alkanes, which is further supported by studying the general polarization (GP) values of a noncovalently entrapped Laurdan dye. The atomic force microscopy (AFM) image shows the formation of ultrathin (height < 2.0 nm) ribbons for the spontaneously assembled sample which eventually produces a large-area 2D nanosheet by the lateral organization. The powder X-ray diffraction pattern of the drop-casted film, prepared from the preformed aggregates, reveals sharp peaks that indicate a crystalline lamellar packing along the direction of the 2D growth. Differential scanning calorimetry trace shows the melting of the crystalline alkyl chain domain at T > 75 °C, which destroys the 2D assembly. Local-scale photoconductivity of the ordered 2D assembly, studied by the flash-photolysis time-resolved microwave conductivity (FP-TRMC) technique, reveals an anisotropic conductivity with ∼3 times larger conductivity along the parallel direction compared to that along the perpendicular one.

H-bonding driven J-type aggregationa nd cooperative supramolecular polymerization of as ulfur-substituted chiral naphthalene-diimide (NDI)-derivative (S,S)-NDI-2 in decane leads to remarkable enhancement of fluorescence quantum yield (43.3 %f rom 0.5 %i nt he monomeric state) and intense CPL signal in the aggregated state with ah igh luminescence dissymmetry factor (g lum)o f4.6 10 À2 .Amixture of NDI-2 with as tructurally similarN DI-derivative NDI-1 (mixture of racemic (S,S)-and(R,R)-isomers and the achiral derivative) in 1:9(NDI-2/NDI-1)r atio, when heated and slowly cooledt or oom temperature, showedn oe nhanced CD band, indicating lack of any preferential helicity.H owever,w hen am onomeric solution of the NDI-1 in tetrahydrofuran (THF) was injectedt op reformed seed of NDI-2 in decane, ap rominentC Ds ignal appeared, indicatingc hiral amplification resulting in induced CPL with high g lum value of 2.0 10 À2 from mostly (> 98.5 %) diastereomericm ixture.

This communication reveals co-assembly of an electron-deficient naphthalene-diimide (NDI)-appended polyurethane (P1) and electron-rich pyrene (Py), forming an organogel with prominent room-temperature ferroelectricity. In a non-polar medium, intra-chain hydrogen-bonding among the urethane groups of P1 produces a folded structure with an array of the NDIs in the periphery, which intercalate Py by charge-transfer (CT)-interaction. Such CT-complexation enables slow crystallization of the peripheral hydrocarbons, causing gelation with nanotubular morphology, in which the wall consists of the alternating NDIÀ Py stack. Such D-A assembly exhibits ferroelectricity (saturation polarization P s � 0.8 μC cm À 2 and coercive field E c � 8 kV cm À 1 at 500 V and 10 Hz frequency) with Curie temperature (T c ) of � 350 K, which can be related to the disassembly of the CT-complex. In the absence of Py, P1 forms spherical aggregates, showing dielectric behaviour.

Lipid-encased chiral supramolecular polymer nanorods (SPNRs), synthesized by the nanoprecipitation method in water from a hydrophobic naphthalene-diimide derivative, exhibit excellent thermal stability, intense fluorescence and strong CPL.

Aromatic units tethered with an azo (−N=N−) functionality comprise a unique class of compounds, known as molecular photoswitches, exhibiting a reversible transformation between their E‐ and Z‐isomers in response to photo‐irradiation. Photoswitches have been explored extensively in the recent past to prepare dynamic self‐assembled materials, optoelectronic devices, responsive biomaterials, and more. Most of such materials involve azobenzenes as the molecular photoswitch and to date, SciFinder lists more than 7000 articles and 1000 patents. Subsequently, a great deal of effort has been invested to improve the photo‐isomerization efficiency and related mesoscopic properties of azobenzenes. Recently, azoheteroarenes and cyclic azobenzenes, such as arylazopyrazoles, arylazoisoxazoles, arylazopyridines, and diazocines, have emerged as second generation molecular photoswitches beyond conventional azobenzenes. These photoswitches offer distinct photoswitching behavior and responsive properties which make them highly promising candidates for multifaceted applications ranging from photoresponsive materials to photopharmacophores. In this minireview, we introduce the structural refinement and photoresponsive properties of azoheteroarenes and diazocines and summarize the state‐of‐the‐art on utilizing these photoswitches as responsive building blocks in supramolecular assembly, material science and photopharmacology, highlighting their versatile photochemical behavior, enhanced functionality, and latest applications.

This article describes a generally applicable supramolecular design for construction of ultrathin two-dimensional (2D) nanosheets with a functionalized surface, by aqueous self-assembly of core-substituted naphthalene diimide (cNDI)-derived π amphiphiles, and explores them as an antibacterial material. In cNDI-1 and cNDI-2, the imide positions are substituted with dodecane chains, while the core substitution differs in the nature of the amine group (primary and quaternary, respectively). On the other hand, cNDI-3 has an identical core substitution to that in cNDI-2 but is attached with the C8 hydrocarbon chain. In water, they exhibit spontaneous self-assembly (critical aggregation concentration < 10–5 M) by synchronized π stacking and alkyl-chain packing in the two orthogonal directions, producing single-molecular-layer-thick (height < 1.5 nm) 2D sheets with amine-functionalized cationic surfaces. These 2D nanosheets exhibit broad-spectrum antibacterial activity against both Gram-positive and Gram-negative strains (Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli), respectively) with rather low minimum inhibitory concentration (MIC) in the range of <100 μg/mL. Among the three, cNDI-2 with the C12 chain and a quaternary amine functionality appears to be the most lethal exhibiting the lowest MIC value (30 μg/mL). Hemolysis of red blood cells remains at <5% even at a cNDI concentration of 10× MIC, suggesting excellent hemocompatibility of these 2D nanosheets, which is also evident from the MTT assay showing that >80% mammalian cells (HeLa) remain viable with up to 200 μg/mL of these molecules. Mechanistic investigations by scanning electron microscopy, live/dead fluorescence assay, and inner/outer membrane permeability assays strongly indicate the nonspecific membrane disruption mechanism for killing of bacteria. Furthermore, these 2D nanosheets display a strong ability to eradicate the bacterial biofilm of both S. aureus and E. coli . With less than 100 μg/mL of a given cNDI molecule, a biofilm (aged for 96 h) can be fully eradicated, which makes them exemplary materials for tackling the emerging health concern on bacterial infection and drug-resistant pathogens.