Chirality of aromatic bis-imides from their circular dichroism spectra

Gawroński, Jacek; Brzostowska, Małgorzata; Kacprzak, Karol; Kołbon, Halina; Skowronek, Paweł

doi:10.1002/(sici)1520-636x(2000)12:4<263::aid-chir12>3.0.co;2-9

Cited by 67 publications

(54 citation statements)

References 22 publications

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“…9 Fluorescence and circular dichroism (CD) spectroscopy were compatible with these restrictive conditions. The NDI chromophore39 of channel 1 n and the DAN fluorophore40 of ligand 2 were available as intrinsic probes. The otherwise invaluable blue emission of the p‐ octiphenyl stave7–9 was completely quenched by the NDI hoops.…”

Section: Resultsmentioning

confidence: 99%

“…The CD spectrum of rod 1 in water and the “membrane‐mimetic” 2,2,2‐trifluoroethanol (TFE) exhibited a strong band‐I Cotton effect with vibrational fine structure overlapping the exciton band splitting (Figure 5A, black). The observed bisignate band‐I Cotton effect originates from exciton coupling of non‐parallel N,N‐polarized electric π–π* transitions between two NDI chromophores that are positioned close in space with a well‐defined and significant twist 39. 42 The magnitude of the observed CD amplitude around A = −24 m −1 cm −1 was comparable to that of pertinent covalent CD model compounds like the classical 1 R ,2 R ‐cyclohexanediamine derivative ( A =Δ ε 1 (391 nm) − Δ ε 2 (∼353 nm)) 39.…”

Section: Resultsmentioning

confidence: 99%

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Ligand‐Gated Synthetic Ion Channels

Talukdar

Bollot

Mareda

et al. 2005

Chemistry A European J

112

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Supramolecular pi-stack architecture is fundamental in DNA chemistry but absent in biological and synthetic ion channels and pores. Here, a novel rigid-rod pi-stack architecture is introduced to create synthetic ion channels with characteristics that are at the forefront of rational design, that is, ligand gating by a conformational change of the functional supramolecule. Namely, the intercalation of electron-rich aromatics is designed to untwist inactive electron-poor helical pi-stacks without internal space into open barrel-stave ion channels. Conductance experiments in planar lipid bilayers corroborate results from spherical bilayers and molecular modeling: Highly cooperative and highly selective ligand gating produces small, long-lived, weakly anion selective, ohmic ion channels. Structural studies conducted under conditions relevant for function provide experimental support for helix-barrel transition as origin of ligand gating. Control experiments demonstrate that minor structural changes leading to internal decrowding suffice to cleanly annihilate chiral self-organization and function.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Ligand‐Gated Synthetic Ion Channels

Talukdar

Bollot

Mareda

et al. 2005

Chemistry A European J

112

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“…In CHCl 3 , this signal transitioned to a positive couplet due to a change to P helicity in the nanobelt assemblies. 16 In contrast, a flat line was produced in TFE, indicative of the nonaggregated state of A in this solvent, as similarly revealed by UV and TEM spectra. Assignment of intermolecular helical orientation of the terthiophene chromophore was not possible due to the overlap of the ππ* transitions of the terthiophene (300425 nm) and NDI (350400 nm) chromophores.…”

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confidence: 71%

1D Self-assembly of Terthiophene (3T)–Naphthalenediimide (NDI) Dyad

Kim¹,

Parquette²

2014

Chemistry Letters

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This work describes a strategy to create terthiophene (3T) naphthalenediimide (NDI) nanostructures via the β-sheet selfassembly of a functionalized dipeptide. The dipeptide assembles into 1D nanofibers in organic solvents and forms a self-supporting organogel at low concentrations in CH 2 Cl 2 . The nanostructures engage in extensive intermolecular ππ stacking interactions.An important challenge in organic materials is to be able to program small and molecular building blocks to precisely assemble into multiscale and multifunctional superstructures that capture, transport, and process various forms of energy.1 Predictable strategies to create segregated and bicontinuous arrays of interpenetrating donor (D) and acceptor (A) chromophores are needed to optimize charge separation and transport within optoelectronic materials.2 Thus, the 1D self-assembly of DA molecules is emerging as a potential strategy to tune the properties of thin film materials and devices. 3 The cofacial π-stacking interactions that often comprise such nanostructures are thought to provide pathways for charge transport and energy migration and are expected to produce maximal charge carrier mobilities. 4 Although considerable progress has been realized over the last several years, precise control of the interactions of chromophores within self-assembled nanostructures remains difficult.Hydrogen-bonddriven self-assembly offers a directional strategy to predictably organize D and A chromophores over long distances and has recently led to new functional electronic materials.5 Peptide-based β-sheet aggregation provides a modular method to construct well-defined nanostructures that are stabilized by intermolecular hydrogen-bonding interactions.6 Notably, we have developed strategies based on peptide β-sheet formation and amphiphilic self-assembly in water to create a variety of 1D nanostructures ranging from nanotubes 7 to 1D fibers and ribbons 8 from very simple building blocks. This design strategy is based on prior studies demonstrating the selfassembly of a series of dilysine peptides functionalized at the ε-amino position with a single naphthalenediimide (NDI) chromophore in water. For example, the β-sheet self-assembly of a series of dilysine peptides functionalized at the ε-amino position with a single NDI chromophore produced nanofibers and nanoribbons in water.8d These dipeptide sequences reflect an alternating polar and nonpolar amphipathic pattern, which is commonly observed in natural and isolated synthetic, antiparallel β-sheet structures.9 The self-assembly strategy further capitalizes on an aromatic chromophore to drive aggregation via hydrophobic effects and ππ stacking interactions in aqueous media. Time-resolved fluorescence anisotropy experiments have shown that efficient energy migration occurs within the resultant π-aggregated NDI assemblies. 7c,10 This strategy was versatile with respect to the N-terminal substituent. For example, an Fmoc chromophore appended to this position of the dipeptide affords a hydrogel comprising ...

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“…Their electronic excited states were recently characterized and the intense -* transitions shown below were found suitable for interchromophoric exciton couplings. 4 Elements B are composed of aromatic chromophores with intense -* transitions and are linked to A through a short chiral chain (Fig. 3).…”

Section: Results and Discussion Molecules To Studymentioning

confidence: 99%