Naphthalene Diimide Core Research Articles

Polymorph Screening of Core-Chlorinated Naphthalene Diimides with Different Fluoroalkyl Side-Chain Lengths.

In this work, naphthalenediimide (NDI) derivatives are widely studied for their semiconducting properties and the influence of the side-chain length on the crystal packing is reported, along with the thermal properties of three core-chlorinated NDIs with different fluoroalkyl side-chain lengths (CF3-NDI, C3F7-NDI and C4F9-NDI). The introduction of fluorinated substituents at the imide nitrogen and addition of strong electron-withdrawing groups at the NDI core are used to improve the NDI derivatives air stability. The new compound, CF3-NDI, was deeply analyzed and compared to the well-known C3F7-NDI and C4F9-NDI, leading to the discovery and solution of two different crystal phases, form α and solvate form, and a solid solution of CF3-NDI and CF3-NDI-OH, formed by the decomposition in DMSO.

Commercializable Naphthalene Diimide Anolytes for Neutral Aqueous Organic Redox Flow Batteries

AbstractNeutral aqueous organic redox flow batteries (AORFBs) hold the potential to facilitate the transition of renewable energy sources from auxiliary to primary energy, the commercial production of anolyte materials still suffers from insufficient performance of high‐concentration and the high cost of the preparation problem. To overcome these challenges, this study provides a hydrothermal synthesis methodology and introduces the charged functional groups into hydrophobic naphthalene diimide cores, and prepares a series of high‐performance naphthalene diimide anolytes. Under the synergistic effect of π–π stacking and H‐bonding networks, the naphthalene diimide exhibits excellent structural stability and the highest water solubility (1.85 M for dex‐NDI) reported to date. By employing the hydrothermal method, low‐cost naphthalene diimides are successfully synthesized on a hundred‐gram scale of $0.16 g−1 ($2.43 Ah−1), which is also the lowest price reported to date. The constructed full battery achieves a high electron concentration of 2.4 M, a high capacity of 54.4 Ah L−1, and a power density of 318 mW cm−2 with no significant capacity decay observed during long‐duration cycling. These findings provide crucial support for the commercialization of AORFBs and pave the way for revolutionary developments in neutral AORFBs.

Commercializable Naphthalene Diimide Anolytes for Neutral Aqueous Organic Redox Flow Batteries.

Neutral aqueous organic redox flow batteries (AORFBs) hold the potential to facilitate the transition of renewable energy sources from auxiliary to primary energy, the commercial production of anolyte materials still suffers from insufficient performance of high-concentration and the high cost of the preparation problem. To overcome these challenges, this study provides a hydrothermal synthesis methodology and introduces the charged functional groups into hydrophobic naphthalene diimide cores, and prepares a series of high-performance naphthalene diimide anolytes. Under the synergistic effect of π-π stacking and H-bonding networks, the naphthalene diimide exhibits excellent structural stability and the highest water solubility (1.85 M for dex-NDI) reported to date. By employing the hydrothermal method, low-cost naphthalene diimides are successfully synthesized on a hundred-gram scale of $0.16 g-1 ($2.43 Ah-1), which is also the lowest price reported to date. The constructed full battery achieves a high electron concentration of 2.4 M, a high capacity of 54.4 Ah L-1, and a power density of 318 mW cm-2 with no significant capacity decay observed during long-duration cycling. These findings provide crucial support for the commercialization of AORFBs and pave the way for revolutionary developments in neutral AORFBs.

Naphthalene Diimide-Based Orange Emitting Luminogen: A Fluorometric Probe for Thiol Sensing through the Click Reaction.

Fluorometric sensors have gained considerable attention in various fields, including environmental monitoring, biomedical research, and clinical diagnostics. This article delineates the fabrication of an orange emitting naphthalene diimide (NDI) derivative consisting of maleimide moiety (NDI-mal) for fluorometric sensing of thiols. Spherical shaped organic nanoparticles (∼100-150 nm) were constructed by NDI-mal in dimethyl sulfoxide (DMSO)/dimethylformamide (DMF)-water through J-type aggregation. NDI-mal displayed self-assembly driven aggregation-induced emission (AIE) through excimer formation at λem= 588 nm at fw = 99 vol % DMSO/DMF-water. Naphthyl residue at both terminals of NDI-mal facilitates intramolecular charge transfer (ICT) from the donor naphthyl residue to the acceptor NDI core. The fluorescence intensity of NDI-mal fluorescent organic nanoparticles (FONPs) got quenched in the presence of thiols due to thiol-maleimide adduct formation (Michael addition). NDI-mal FONPs selectively probed thiol functionalized small molecules (4-aminothiophenol), biomolecules (glutathione (GSH)), and proteins (reduced BSA) with high sensitivity having a limit of detection of 15.3 nM, 6.0 nM, and 9.2 ng/mL, respectively. Importantly, thiol sensing was selective against analogous small molecules, biomolecules, and proteins devoid of thiol moieties. Cellular imaging demonstrated selective diagnosis of cancer cells by NDI-mal FONPs through quenching of its emission upon interaction with thiols in B16F10 cells due to the high abundance of GSH in cancer cells compared to NIH3T3 cells. NDI-mal FONPs emitted their native fluorescence inside cells subjected to reactive oxygen species mediated thiol oxidation via Fenton's reaction. Notably, GSH-maleimide adduct formation by NDI-mal FONPs displayed notable therapeutic efficacy against cancer cells having ∼2.4-fold higher killing of B16F10 in comparison to NIH3T3 cells possibly through oxidative stress induced apoptosis owing to the depletion in the GSH level. Thus, NDI-mal AIE-gen successfully emerged as a selective and sensitive probe toward thiols through thiol-maleimide click chemistry with therapeutic ability against cancer cells in the absence of systematic intervention.

Ambient-Stable n-Type Carbon Nanotube/Organic Small-Molecule Thermoelectrics Enabled by Energy Level Control.

The stability of n-type organic and hybrid thermoelectric materials is limited in terms of their practical application to p-n parallel thermoelectric devices. We demonstrate the ambient stability of an n-type single-walled carbon nanotube/organic small-molecule (SWNT/OSM) hybrid by deepening the lowest occupied molecular orbital energy level. This hybrid exhibited the best figure of merit (0.032) among n-type SWNT/OSM hybrid thermoelectrics and an enhanced power factor of 291.0 μW m-1 K-2. Furthermore, we observed that the n-type thermoelectric stability of a hybrid of SWNT and pip containing two N-ethylpiperidinyl groups on both sides of a naphthalenediimide core was retained at 87% over 7 months (220 days) under ambient conditions without encapsulation.

Better Covalent Connection in a Molecular Triad Enables More Efficient Photochemical Energy Storage.

Numerous studies have explored the kinetics of light-induced charge separation and thermal charge recombination in donor-acceptor compounds, but quantum efficiencies have rarely been investigated. Here, we report on two essentially isomeric molecular triads, both comprising a π-extended tetrathiafulvalene (ExTTF) donor, a ruthenium(II)-based photosensitizer, and a naphthalene diimide (NDI) acceptor. The key difference between the two triads is how the NDI acceptor is connected. Linkage at the NDI core provides stronger electronic coupling to the other molecular components than connection via the nitrogen atoms of NDI. This change in molecular connectivity is expected to accelerate both energy-storing charge separation and energy-wasting charge recombination processes, but it is not a priori clear how this will affect the triad's ability to store photochemical energy; any gain resulting from faster charge separation could potentially be (over)compensated by losses through accelerated charge recombination. The new key insight emerging from our study is that the quantum yield for the formation of a long-lived charge-separated state increases by a factor of 5 when going from nitrogen- to core-connected NDI, providing the important proof of concept that better molecular connectivity indeed enables more efficient photochemical energy storage. The physical origin of this behavior seems to root in different orbital connectivity pathways for charge separation and charge recombination, as well as in differences in the relevant orbital interactions depending on NDI connection. Our work provides guidelines for how to discriminate between energy-storing and energy-wasting electron transfer reactions in order to improve the quantum yields for photochemical energy storage and solar energy conversion.

Organic nanoparticles with tunable AIE derived from amino acids appended naphthalenediimide based amphiphiles

Fluorescent organic nanoparticles (FONPs) are unique cooperative manifestations of supramolecular self-aggregates and luminescent nanoparticles. In this work, we developed naphthalenediimide (NDI) based amphiphiles (NDI-1-9) having amino acids substitution from L-alanine to L-phenyl alanine to 3-(2-naphthyl)-L-alanine in absence and presence of alkyl spacer (C-6, C-11). Formation of self-aggregated spherical organic nanoparticles of ∼50 nm took place at and above 50 vol% water or methyl cyclohexane (MCH) in different binary solvent systems (DMSO/DMF-water, CHCl3-MCH) via J-aggregation. In case of NDI-1-3 (amino acids are directly connected to the NDI) self-assembled FONPs (MCH in CHCl3) exhibited aggregation-induced emission (AIE) through excimer formation. Red shift in the emission maxima were observed from 484 nm to 495 nm, and 590 nm, respectively with increasing π electron cloud at substituted donor from NDI-1 to NDI-3. Alongside, in case of aromatic amino acids substitution, FONPs of 6-amino caproic acid spacer containing NDI derivatives (NDI-5 and NDI-6) showed AIE at 505 nm and 545 nm (water in DMF/DMSO). Corresponding 11-amino undecanoic acid containing analogues (NDI-8 and NDI-9) showed AIE at 480 nm and 585 nm in CHCl3-MCH and DMF/DMSO-water. The multi colour emission from blue-green to yellow-orange with enrichment of π-electron cloud density in the side chain substitution of NDI was observed possibly due to the facilitated electron transfer at a lesser energy to the electron deficient NDI core that resulted in red shifted emission maxima. This was further clarified by regulating the availability of π-electrons of phenyl ring of NDI-2 by including electron withdrawing –NO2 and donating -OMe groups at the molecular backbone (NDI-2a and NDI-2b) that showed blue shifted (475 nm) and red shifted (570 nm) emission maxima with respect to NDI-2 (495 nm). However, increase in alkyl spacer length between side chain substitution and NDI core yielded relatively lower quantum yield presumably due to the impeded electron transfer.

Abstract 3098: Structure-based design rules for potent quadruplex-binding compounds based on the naphthalene diimide core

Abstract Quadruplex nucleic acids (G4s) are four-stranded arrangements formed by guanine-rich tracts of DNA or RNA, held together by Hoogsteen hydrogen-bonded guanine quartets. G4 sequences are widely though not randomly distributed in the human genome. They are over-represented in telomeres and in the regulatory regions of many cancer-related genes such as KIT, MYC, VEGF, RAS and HIF. G4 structures can be unwound by helicase activity but can be stabilized by the binding of high-affinity small molecules. The compound QN-302, a tetra-substituted naphthalene diimide (ND) derivative, has nanomolar affinity and selectivity for several DNA and RNA G4s over duplex DNA. QN-302 has single-digit nM anti-proliferative activity in a panel of human pancreatic cancer (PDAC) cell lines (Ahmed et al., ACS Med Chem Lett, 2020, 11, 1634-1644). It has significant anti-tumor activity in several models for PDAC - in a MIA-PACA2 xenograft, in the genetic KPC model and in an orthotopic BX-PC3 model. QN-302 is currently in an advanced stage of pre-IND development by Qualigen Inc as a novel anti-cancer agent. QN-302 is the latest in several generations of NDs developed by us and designed by computer modelling based on earlier G4 co-crystal structures determined in this laboratory. The database of seven ND-containing crystal structures includes four different NDs with distinct side chain end groups, all with intramolecular telomeric parallel G4s. End-groups include N-methyl piperazine, hydroxyl, morpholino and N-dimethyl. These structures have been systematically compared for example using least-squares overlays of the structures. All the structures have their four substituents positioned each in a G4 groove, although there are significant differences in orientations of the end groups. Surprisingly, the naphthalene diimide cores do not retain the same orientation in each structure, with three distinct orientations being apparent. Examination of ND core overlap with the adjacent G-quartet has revealed variation in the degree of heterocycle-guanine base overlap, which is dependent on the nature and size of each substituent. However, all structures show minimal ND-guanine overlap, with typically just one out of four guanines in a G-quartet being involved. This strongly implies that most of the contribution to ND-G4 affinity comes from the side chains, and especially from the protonated end groups. These and other observations have led us to develop a structure-activity framework for tetra-substituted NDs, which has culminated in their optimization and the design of QN-302, with enhanced cellular potency and G4 affinity compared to previous NDs. Citation Format: Stephen Neidle. Structure-based design rules for potent quadruplex-binding compounds based on the naphthalene diimide core [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3098.

Highly Stable Metal-Organic Framework with Redox-Active Naphthalene Diimide Core as Cathode Material for Aqueous Zinc-Ion Batteries.

Recently, metal-organic frameworks (MOFs) as the cathode materials for aqueous zinc-ion batteries (ZIBs) received growing attention. Herein, a novel MOF, Ni-Ndi-trz (Ndi-trz=2,7-di(4H-1,2,4-triazol-4-yl)benzo[lmn][3,8]phenanthroline-1,3,6,8(2H,7H)-tetraone) was synthesized through a solvothermal method. Its rational design using a naphthalene diimide (Ndi) core allowed the formation of a four-fold interpenetrated pcu (primitive cubic) topology. The as-synthesized Ni-Ndi-trz is highly stable over a wide pH range (0-12) for 30 days, which is critical to ensure the decent cyclability of zinc-ion batteries (ZIBs). When used as the cathode material of ZIBs, it shows a high initial specific capacity of 90.7 mAh g-1 and excellent cycling stability. Remarkably, three-electrode system tests, ex situ FTIR, UV/Vis and XPS spectra revealed that the Ndi core of Ni-Ndi-trz undergoes a reversible interconversion between the keto and enol forms when interacting with Zn2+ ions. This work may shed light on the feasibility of designing novel MOFs and exploring their mechanisms for zinc ion batteries.

Controlling π-π Interactions of Highly Soluble Naphthalene Diimide Derivatives for Neutral pH Aqueous Redox Flow Batteries.

Organic redox-active molecules are a promising platform for designing sustainable, cheap, and safe charge carriers for redox flow batteries. However, radical formation during the electron-transfer process causes severe side reactions and reduces cyclability. This problem is mitigated by using naphthalene diimide (NDI) molecules and regulating their π-π interactions. The long-range π-stacking of NDI molecules, which leads to precipitation, is disrupted by tethering four ammonium functionalities, and the solubility approaches 1.5m in water. The gentle π-π interactions induce clustering and disassembling of the NDI molecules during the two-electron transfer processes. When the radical anion forms, the antiferromagnetic coupling develops tetramer and dimer and nullifies the radical character. In addition, short-range-order NDI clusters at 1m concentration are not precipitated but inhibit crossover. They are disassembled in the subsequent electron-transfer process, and the negatively charged NDI core strongly interacts with ammonium groups. These behaviors afford excellent RFB performance, demonstrating 98% capacity retention for 500 cycles at 25mA cm-2 and 99.5% Coulombic efficiency with 2m electron storage capacity.

Supramolecular alternating copolymers with highly efficient fluorescence resonance energy transfer.

This article reports alternating supramolecular copolymerization of two naphthalene-diimide (NDI)-derived building blocks (NDI-1 and NDI-2) under thermodynamic control. Both monomers contain a central NDI chromophore, attached to a hydrocarbon-chain and a carboxylic-acid group. The NDI core in NDI-2 is symmetrically substituted with two butane-thiol groups, which makes it distinct from NDI-1. In decane, a 1 : 1 mixture of NDI-1 and NDI-2 shows spontaneous gelation and a typical fibrillar network, unlike the behavior of either of the components individually. The solvent-dependent UV/vis spectrum of the mixed sample in decane shows bathochromically shifted sharp absorption bands and a sharp emission band (holds a mirror-image relationship) with a significantly small Stokes shift compared to those in CHCl3, indicating J-aggregation. In contrast, the aggregated spectra of the individual monomers show broad structureless features, suggesting ill-defined aggregates. Cooling curves derived from the temperature-dependent UV/vis spectroscopy studies revealed early nucleation and a signature of well-defined cooperative polymerization for the mixed sample, unlike either of the individual components. Molecular dynamics simulations predicted the greatest dimer formation tendency for the NDI-1 + NDI-2 (1 : 1), followed by pure NDI-1 and NDI-2. Theoretical studies further revealed a partial positive charge in the NDI ring of NDI-1 when compared to NDI-2, promoting the alternating stacking propensity, which is also favored by the steric factor as NDI-2 is core-substituted with alkyl thiols. Such theoretical predictions fully corroborate with the experimental results showing 1 : 1 stoichiometry (from Job's plot) of the two monomers, indicating alternate stacking sequences in the H-bonded (syn-syn catemer type) supramolecular copolymer. Such alternating supramolecular copolymers showed highly efficient (>93%) fluorescence resonance energy transfer (FRET).

A room temperature functioning ammonia sensor utilising a bis-phenylalanine naphthalene diimide

An organic semiconductor, coded as NDI-A, comprising a naphthalene diimide core functionalised axially with phenylalanine derivatives has been evaluated for ammonia gas sensing at room temperature. A significant change in the current intensity of NDI-A-based sensor has been recorded upon exposure to ammonia with different concentrations (50, 25, 12.5, 6 and 2 ppm). The NDI-A-based sensor showed high sensitivity (66 %) towards 50 ppm ammonia, quick response and recovery (15.3 s and 32 s), low limit of detection (2 ppm). Promising features of high selectivity, good recyclability and stability were also evaluated. Importantly, the sensor exhibited excellent sensing performance at high humid environments with a response of 55 % towards 50 ppm ammonia at 90 % relative humidity. The high sensing performance of NDI-A sensor can be attributed to a number of factors, including the favourable morphology of the active film, containing random pores and voids, and design principles through the presence of -COOH groups which can effectively interact with ammonia through acid-base interactions.

Medium effects on the fluorescence of Imide-substituted naphthalene diimides

Naphthalene diimides (NDIs) are a common class of chromophores used in photon harvesting applications due to their functional malleability through substitution of the NDI core. However, some derivatives with substitution at the imide position of the NDI core only become emissive in electron-rich aromatic solvents. This study examines this phenomenon from both an experimental and theoretical perspective, in order to understand how NDIs interact with each other and the surrounding medium upon photoexcitation. We report the photophysical properties of cyclohexyl and several aromatic imide-substituted NDI derivatives, and show that fluorescence properties are strongly influenced by solvation in more electron-rich aromatic solvents (e.g. toluene, xylene, mesitylene). Theoretical modeling supports strong interactions, including ground state charge-transfer complexation, with aromatic solvents. In solid poly(methyl methacrylate) (PMMA) and poly(styrene) (PS) film media, both aggregation and complexation are shown to contribute to absorption and emission properties. The results also demonstrate that aromatic imide substituents not only act to provide steric bulk to the NDI chromophore but participate in interactions with the surrounding medium that affect the overall photophysical properties.

Furan functionalized naphthalenediimide semiconductors with different N-alkyl chains for n-type organic thin-film transistor applications

Development of n-type organic semiconductors (OSCs) is necessary in order to develop complementary electronics based on organic thin-film transistors (OTFTs). In this investigation, we designed and synthesized a series of four novel imide- and core-substituted naphthalene diimide (NDI) molecules. The molecular architecture was altered via introduction of different alkyl side chains (octyl and 2-ethylhexyl) to the imide-N positions and 2-dicyanomethylene-3-cyano-4,5,5-trimethyl-2,5-dihydrofuran (TCF) to the NDI core. The NDI-TCF derivatives are abbreviated as NDI-TCF1A, NDI-TCF1B, NDI-TCF2A, and NDI-TCF2B, using a “1” or “2” to indicate the number of TCF subunits at the NDI core, and an “A” or a “B” to indicate an octyl or a 2-ethylhexyl alkyl chain at the imide-N position, respectively. All four compounds displayed similar photophysical properties but exhibited different electrochemical properties with lower LUMO levels of −4.25 eV, −4.33 eV, −4.27 eV and −4.35 eV for NDI-TCF1A, NDI-TCF1B, NDI-TCF2A, and NDI-TCF2B, respectively. These LUMO levels suggest a capacity for electron transport. Furthermore, the NDI-TCF chromophores were incorporated into OTFTs and systematically studied on the relationship between the NDI-TCF molecular architecture and electron transport properties. NDI-TCF1A and NDI-TCF1B displayed more consistent OTFT performance than NDI-TCF2A and NDI-TCF2B. NDI-TCF1A and NDI-TCF1B exhibited low threshold voltages (VT) of −0.43 V ± 4.78 V and 6.12 V ± 6.63 V, respectively, electron mobilities (μe) of ca. 3 × 10−5 cm2V−1s−1, and on/off (ION/OFF) ratios of ca. 103. Insofar that TCF facilitates electron transport, the OTFT data suggest that the number of TCF subunits affect OTFT performance via thin-film morphology. The thin-film morphology of NDI-TCF1A, NDI-TCF1B, NDI-TCF2A, and NDI-TCF2B was studied using atomic force microscopy (AFM) technique and supported by X-ray diffraction measurements.

Structure-activity relationship studies on divalent naphthalene diimide G quadruplex ligands with anticancer and antiparasitic activity

Naphthalene diimide (NDI) is a central scaffold that has been commonly used in the design of G-quadruplex (G4) ligands. Previous work revealed notable anticancer activity of a disubstituted N-methylpiperazine propyl NDI G4 ligand. Here, we explored structure–activity relationship studies around ligand bis-N,Ń-2,7-(3-(4-methylpiperazin-1-yl)propyl)-1,4,5,8-naphthalenetetracarboxylic diimide, maintaining the central NDI core whilst modifying the spacer and the nature of the cationic groups. We prepared new disubstituted NDI derivatives of the original compound and examined their in vitro antiproliferative and antiparasitic activity. Several N-methylpiperazine propyl NDIs showed sub-micromolar activity against Trypanosoma brucei and Leishmania major parasites with up to 30 fold selectivity versus MRC-5 cells. The best compound was a dimorpholino NDI with an IC50 of 0.17 μM against T.brucei and 40 fold selectivity versus MRC-5 cells. However, no clear correlation between G4 binding of the new NDI derivatives and antiproliferative or antiparasitic activity was observed, indicating that other mechanisms of action may be responsible for the observed biological activity.

Luminescence turn-on response of naphthalene diimide based chemosensor with Formaldehyde: A novel stratagem for estimation of formaldehyde in storage fish samples

A new strategy has been developed for selective estimation of toxic Formaldehyde (FA) in storage fish samples by a simple chemosensor (BNDI) based on naphthalene diimide core in aqueous medium at neutral pH. The rapid “lightning–up” fluorescence feature of BNDI has been implied to detect and estimate aqueous FA selectively at very low concentration. The chemosensing properties of BNDI with aqueous FA have been established through a unique interaction pattern which is proven by different spectroscopic and theoretical analysis.

A Nonionic Alcohol Soluble Polymer Cathode Interlayer Enables Efficient Organic and Perovskite Solar Cells.

The choice of interfacial materials and their properties play a critical role in determining solar cell performance and stability. For compatibility with roll-to-roll printing, it is desirable to develop stable cathode interface layers (CILs) that can be processed over the photoactive layer using orthogonal solvents. In this study, an n-type naphthalene diimide core and oligo (ethylene glycol) side-chain-based conjugated polymer is reported as a universal, efficient CIL for organic and perovskite photovoltaics. Besides good thermal stability and easy processing in alcohol/water, the new CIL is found to possess electron transport properties with an electrical conductivity of 2.3 × 10–6 S cm–1, enabling its use as a CIL with a film thickness of up to ∼35(±2) nm. Utilizing the new CIL, 16% power conversion efficiency (PCE) is achieved for organic solar cells (OSCs) based on the PM6-Y6 photoactive layer (8.9% PCE for no CIL and 15.1% with state-of-the-art CIL, PDINO), and perovskite solar cells from methylammonium lead iodide yielded a PCE of 17.6%. Compared to the reference devices, the new CIL reduced trap-assisted carrier recombination and increased the built-in potential by 80 mV, simultaneously enhancing all photovoltaic parameters. Moreover, new CIL based devices had better photostability with no burn-in losses.

Bluish Hydrochromic Naphthalenediimide Salt: Change of Hydrogen-bond Interactions as the New Mechanism of Vapochromism

Naphthalenediimide (NDI) is generally a yellowish to reddish chromophore, which shows vapochromism by the alternation of charge-transfer (CT) interactions at the NDI core. On the contrary, we discovered that the deprotonation of N,N′-dihydroxy-1,4,5,8-naphthalenetetracarboxdiimide (NDI-(OH)2) gave a bluish organic salt with a hydrochromic property, which has been rare in conventional NDI derivatives. On the basis of the structural analyses and the calculation, the origin of the hydrochromism can be explained by the change of hydrogen-bond interaction between the anionic imide group and H2O molecules.

Flower‐Like Morphology of Naphthalene Diimides Containing tetra‐L‐ and D‐Alanine

AbstractTwo structural isomers of naphthalene diimide (NDI) chromophores NDI‐3 and NDI‐4, which are NDI imide position functionalised with four L‐/D‐alanine subunits. Density functional theory calculations revel that HOMO molecular orbital is localized on N‐phenyl substituent and LUMO on NDI core. Further, the UV‐vis, fluorescence measurements show that both the derivatives i. e. NDI‐3 and NDI‐4 exhibit changes in optical and photophysical properties with the addition of non‐polar i. e. methylcyclohexane in chloroform as well as water in tetrahydrofuran. From these results, it is clear that the structural isomers NDI‐3 and NDI‐4 shows a significant solvatochromic effect, which ascribed to the aggregation effect via π‐π stacking of NDI core along with hydrogen‐bonding between alanine side chains. Scanning electron microscopy (SEM) and polarized optical microscopy images clearly demonstrate formation of flower like morphology in THF:H2O and fiber nanostructure in CHCl3:MCH for both NDI‐3 and NDI‐4. Interestingly, only NDI‐4 in CHCl3:MCH (4 : 6, v/v) solvent mixture produces rose‐like flower microstructures.

Naphthalenediimides with Cyclic Oligochalcogenides in Their Core.

Naphthalenediimides (NDIs) are privileged scaffolds par excellence, of use in functional systems from catalysts to ion channels, photosystems, sensors, ordered matter in all forms, tubes, knots, stacks, sheets, vesicles, and colored over the full visible range. Despite this extensively explored chemical space, there is still room to discover core-substituted NDIs with fundamentally new properties: NDIs with cyclic trisulfides (i.e., trisulfanes) in their core absorb at 668 nm, emit at 801 nm, and contract into disulfides (i.e., dithietes) upon irradiation at <475 nm. Intramolecular 1,5-chalcogen bonds account for record redshifts with trisulfides, ring-tension mediated chalcogen-bond-mediated cleavage for blueshifts to 492 nm upon ring contraction. Cyclic oligochalcogenides (COCs) in the NDI core open faster than strained dithiolanes as in asparagusic acid and are much better retained on thiol exchange affinity columns. This makes COC-NDIs attractive not only within the existing multifunctionality, particularly artificial photosystems, but also for thiol-mediated cellular uptake.