[4]Helicene–Squalene Fluorescent Nanoassemblies for Specific Targeting of Mitochondria in Live‐Cell Imaging

Babič, Andréj; Pascal, Simon; Duwald, Romain; Moreau, Dimitri; Lacour, Jérôme; Allémann, Éric

doi:10.1002/adfm.201701839

Cited by 34 publications

(37 citation statements)

References 56 publications

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“…In 2013, Lacour et al reported the synthesis of cationic [6]helicene as new members of chiral helicenium compounds. 269 Using a modular synthetic pathway, the authors were able to obtain heterohelicenes [278][BF 4 ]- [280][BF 4 ] on a multigram scale, the latter being resolved using (∆)-and (Λ)-BINPHAT anions in a similar way as for salt [260] [6]helicenium [280][BF 4 ] with electrophile and nucleophile reagents. Bottom: ECD and VCD spectra of (P)- [280][PF 6 ] (blue for ECD and red for VCD) and (M)- [280][PF 6 ] green for ECD and blue for VCD), with R = n-propyl.…”

Section: Synthesis Of Carbocationic Aza[6]helicenesmentioning

confidence: 99%

Enantioenriched Helicenes and Helicenoids Containing Main-Group Elements (B, Si, N, P)

2019

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In this review, we discuss the rich chemistry of helicenes and helicenoids containing maingroup elements. Enantioenriched helicenic derivatives containing main-group elements B, Si, N and P, either incorporated within the helical backbone or grafted to it, will be thoroughly presented. We will describe their synthesis, resolution, and asymmetric synthesis, their structural features, electronic and chiroptical properties, emission, together with other photochemical properties and applications. OUTLINE 14 The absorption spectrum of 19c recorded in CH 2 Cl 2 solutions exhibited a maximum at 376 nm which is significantly red shifted compared with that of double [5]helicene 19a (310 nm) due to the more extended π-conjugation in 19c. According to TD-DFT calculations, the low-energy absorption band from 400 to 500 nm is assignable to the HOMO→LUMO transition corresponding to a π−π* transition of the fully conjugated bis-helical system. DFT calculations revealed a very high theoretical isomerization barrier of 45.1 kcal/mol for the (P,P)/(M,M)-19c stereoisomer, i.e. 4.4 kcal/mol higher than the (P,M) stereoisomer (not observed experimentally). The high configurational stability of 19c enabled to obtain the pure (P,P)and (M,M)-19c by chiral HPLC (Daicel Chiralcel IE column; EtOAc/MeOH = 9:1 as eluent) and to study their chiroptical properties. The ECD spectrum of (P,P)-19c in CH 2 Cl 2 displayed two strong positive bands at 275 and 320 nm, a strong negative one at 375 nm and a broad and less intense one between 425-475 nm. 52 Note that the isomerization barrier of the OBO-fused double [7]helicene is much higher than for oxabora[6]helicene 9 (vide supra) and higher than carbo[7]helicene (42.0 kcal/ mol), indicating the advantage of double helicenes over monohelicenes in terms of conformational stability. Indeed no racemization was observed upon heating enantiomer (P,P) and (M,M)-19c for 24 h up to 200 °C. 52 Note that in 2017 a longer double OBO-helicene analogue was deposited on a Au(111) under UHV conditions and its surface-assisted cyclodehydrogenation into a planar OBO-perihexacene was observed by STM. 54 Similarly to 6 and 9, the strong bond alternation found in the BOC4 rings of 19a 51 may account for the small NICS value of 1.3 while the surrounding C6 rings, including the distorted central benzene ring, show large negative NICS values (Scheme 3c). For comparison, in the all-carbon analogue tetrabenzo-[a,f,j,o]perylene shown in Scheme 3c, the central C6 ring shows a positive NICS value, indicating substantial antiaromatic character. Notably, molecular orbital calculations of 19a indicate that the HOMO and LUMO are spread over the C6 rings rather than on the boron and oxygen atoms, accounting for the substantial stability of 19a (Scheme 3c). Borahelicenes are efficient blue fluorophores. Indeed, azabora[6]helicene 6 displays blue fluorescence at 447 nm (Table 2), while smaller achiral [4]helicenic systems were successfully used as host materials in phosphorescent OLEDs with efficiencies better than the classical 4,4'...

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Section: Synthesis Of Carbocationic Aza[6]helicenesmentioning

confidence: 99%

Enantioenriched Helicenes and Helicenoids Containing Main-Group Elements (B, Si, N, P)

2019

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“…Bacterial adhesion on these films was directly measured using scanning electron microscopy (SEM) upon dip-inoculation. Most importantly, we herein demonstrate the proof-of-concept that [7]helicene coated graphene monolayer (H-GR) have promising bacterial antifouling properties with a reduction in the bacterial adhesion of S. aureus up to 96.8% compared to bare graphene surfaces.…”

Section: Introductionmentioning

confidence: 78%

“…Helicene solution was prepared by dissolving 0.1% [7]helicene (purchased from Lach-Ner, Neratovice, Czech Republic, and used as received) in anhydrous dichloromethane via bath-sonication for 10 min at room temperature (23 • C). Then, 5 µL of helicene solution was spread at the air-water interfaces of a Langmuir trough (KSV Nima, Biolin Scientific, Gothenburg, Sweden) ( Figure 1).…”

Section: Methods and Experimentsmentioning

confidence: 99%

Bacterial Antifouling Characteristics of Helicene—Graphene Films

Liu

Bae

et al. 2021

Nanomaterials

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Herein, we describe interfacially-assembled [7]helicene films that were deposited on graphene monolayer using the Langmuir-Schaefer deposition by utilizing the interactions of nonplanar (helicene) and planar (graphene) π–π interactions as functional antifouling coatings. Bacterial adhesion of Staphylococcus aureus on helicene—graphene films was noticeably lower than that on bare graphene, up to 96.8% reductions in bacterial adhesion. The promising bacterial antifouling characteristics of helicene films was attributed to the unique molecular geometry of helicene, i.e., nano-helix, which can hinder the nanoscale bacterial docking processes on a surface. We envision that helicene—graphene films may eventually be used as protective coatings against bacterial antifouling on the electronic components of clinical and biomedical devices.

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“…Compound 8 self‐assembled into Tyr‐MRI nanomicelles in aqueous media using either nanoprecipitation or thin‐film hydration method . The self‐assembly was surprisingly efficient.…”

Section: Resultsmentioning

confidence: 99%

“…Nanoprecipitation method : 3.2 mg (1.0 μmol) of compound 8 was dissolved in a mixture of acetone (200 μL) and ethanol (200 μL). The organic phase was added dropwise into ultrapure water (1.40 mL) using a microsyringe in 5 min under magnetic stirring.…”

Section: Methodsmentioning

confidence: 99%

Self‐Assembled Nanomicelles as MRI Blood‐Pool Contrast Agent

Babič

Vorobiev

Xayaphoummine

et al. 2017

Chemistry A European J

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Gadolinium-loaded nanomicelles show promise as future magnetic resonance imaging (MRI) contrast agents (CAs). Their increased size and high gadolinium (Gd) loading gives them an edge in proton relaxivity over smaller molecular Gd-complexes. Their size and stealth properties are fundamental for their long blood residence time, opening the possibility for use as blood-pool contrast agents. Using l-tyrosine as a three-functional scaffold we synthesized a nanostructure building block 8. The double C18 aliphatic chain on one side, Gd-1,4,7,10-tetraazacyclododecane-1-4-7-triacetic acid (Gd-DO3A) with access to bulk water in the center and 2 kDa PEG on the hydrophilic side gave the amphiphilic properties required for the core-shell nanomicellar architecture. The self-assembly into Gd-loaded monodispersed 10-20 nm nanomicelles occurred spontaneously in water. These nanomicelles (Tyr-MRI) display very high relaxivity at 29 mm s at low field strength and low cytotoxicity. Good contrast enhancement of the blood vessels and the heart together with prolonged circulation time in vivo, makes Tyr-MRI an excellent candidate for a new supramolecular blood-pool MRI CA.

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[4]Helicene–Squalene Fluorescent Nanoassemblies for Specific Targeting of Mitochondria in Live‐Cell Imaging

Cited by 34 publications

References 56 publications

Enantioenriched Helicenes and Helicenoids Containing Main-Group Elements (B, Si, N, P)

Enantioenriched Helicenes and Helicenoids Containing Main-Group Elements (B, Si, N, P)

Bacterial Antifouling Characteristics of Helicene—Graphene Films

Self‐Assembled Nanomicelles as MRI Blood‐Pool Contrast Agent

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