Bright Electrochemiluminescence Tunable in the Near-Infrared of Chiral Cationic Helicene Chromophores

Li, Haidong; Wallabregue, Antoine; Adam, Catherine; Labrador, Geraldine M.; Bosson, Johann; Bouffier, Laurent; Lacour, Jérôme; Šojić, Nešo

doi:10.1021/acs.jpcc.6b11831

Cited by 25 publications

(26 citation statements)

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“…The electrochemical properties of cationic [6]helicenes can be modulated by the nature of the heteroatoms (O, N) contained within the helical core or via the addition of peripheral substituents . The study on cationic [6]helicenes as a molecular redox probes for thin voltammetric films described earlier for the detection of cations is extended here to anions.…”

Section: Resultsmentioning

confidence: 99%

“…The procedures for the preparation of dioxa + [6]helicene, dipropyl and dioctyl diaza + [6]helicenes (diaza + (C 3 ) 2 and diaza + (C 8 ) 2 , respectively) have been previously reported . These derivatives were synthesized in one step from a single common advanced synthetic intermediate (See Figure S1 for structural and synthetic information) . Regioselective bromination and nitration of the dioctyl derivative afforded the diaza + (C 8 ) 2 Br 2 and diaza + (C 8 ) 2 (NO 2 ) 2 moieties, respectively .…”

Section: Methodsmentioning

confidence: 98%

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Ion Transfer Voltammetry in Polyurethane Thin Films Based on Functionalised Cationic [6]Helicenes for Carbonate Detection

et al. 2018

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We explore here molecular ion‐to‐electron redox probes based on cationic diaza, azaoxa, and dioxa [6]helicenes and their derivatives as ion‐to‐electron transducers for the electrochemical detection of anions. These cationic [6]helicenes exhibit reversible and reproducible oxidation/reduction behavior and facilitate the anion transfer of Gaussian shape into polymeric thin layer sensing films. Films composed of bis(2‐ethylhexyl) sebacate (DOS), polyurethane (PU), tetrakis(4‐chlorophenyl)borate tetradodecylammonium salt (ETH 500) and [6]helicenes were interrogated by cyclic voltammetry. Even though the peak separation of 90 mV is larger than ideal, the observed peak width at half maximum of 130 mV and the linear relationship between current and scan rate are near theoretical values, confirming a surface confined process. A Nernstian shift of the peaks with increasing carbonate concentration is obtained in the presence of carbonate ionophore VII incorporated into the thin sensing film. The concentration of carbonate was determined in an unfiltered sample of the Arve river (flowing from Chamonix to Geneva) and compared to a reference method (automatic titrator with potentiometric detection). The results suggested that cationic diaza [6]helicene functionalized with two bromine atoms is an attractive molecular ion‐to‐electron transducer for anion‐selective electrodes.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 98%

Ion Transfer Voltammetry in Polyurethane Thin Films Based on Functionalised Cationic [6]Helicenes for Carbonate Detection

et al. 2018

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“…These derivatives, and novel didodecyl diaza + [6]helicene (diaza + (C 12 ) 2 ), were synthesized in one step from a single common advanced synthetic intermediate following reported procedures .…”

Section: Methodsmentioning

confidence: 99%

Ion Transfer Voltammetry at Thin Films Based on Functionalized Cationic [6]Helicenes

et al. 2017

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We describe a new family of molecular ion‐to‐electron redox probes based on cationic diaza, azaoxa, and dioxa [6]helicenes and their derivatives. Their unique structure combines, in a single framework, two privileged families of molecules – helicenes and triaryl methyl carbenium moieties. These cationic [6]helicenes exhibit reversible and reproducible oxidation/reduction behavior and facilitate the ion transfer into thin layer sensing films composed of bis(2‐ethylhexyl)sebacate (DOS), polyurethane (PU), sodium tetrakis 3.5‐bis(trifluoromethyl)phenyl borate, sodium ionophore X and diaza+(C8)2Br2 for cation transfer. Cyclic voltammetry is used to interrogate the thin films. The cationic response can be tuned by adjusting the membrane loading. Addition of lipophilic cation exchanger into the membrane film results in transfer waves of Gaussian shape for cations. A peak separation of 60 mV and peak width of 110 mV are near the theoretical values for a surface confined process. While Nernstian shifts of the peak potentials with analyte concentration is obtained for membranes based on cationic [6]helicenes and doped with sodium‐selective ionophore X, this ionophore was found to promote a gradual loss of redox active species from the ionophore‐based membranes into the sample solution.

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“…Other applications in electrochemiluminescence or ion transfer voltammetry were also reported for some [4]-and [6]helicene cationic dyes but focused only on racemic compounds. 282,283,284 In collaboration with Prof. Naaman, Lacour investigated aza [4]helicenium derivative [260][BF 4 ] as potential organic spin filter owing to the Chirality Induced Spin Selectivity (CISS) effect. 285,286 Using magnetic conductive probe atomic force microscopy (mCP-AFM) and magnetoresistance measurements set-ups, the authors showed that spin specific electron conduction is measured on chiral helicenium films with an opposite preferred spin for (P) and (M) enantiomers (Figure 38).…”

Section: Applications Of Carbocationic Azahelicenesmentioning

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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Bright Electrochemiluminescence Tunable in the Near-Infrared of Chiral Cationic Helicene Chromophores

Cited by 25 publications

References 68 publications

Ion Transfer Voltammetry in Polyurethane Thin Films Based on Functionalised Cationic [6]Helicenes for Carbonate Detection

Ion Transfer Voltammetry in Polyurethane Thin Films Based on Functionalised Cationic [6]Helicenes for Carbonate Detection

Ion Transfer Voltammetry at Thin Films Based on Functionalized Cationic [6]Helicenes

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

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