Sulfur Bridged Cationic and Neutral [6]Helicenes – Chiral Trityls with Property and Stability Twists

Replacing oxygen and nitrogen by sulfur atoms in cationic [6]helicenes alters their molecular shape, electronic structure, absorption, emission, chemical and configurational stability. A modular synthetic route combining early sulfur incorporation, heteroatom-bridge diversification, and late-stage functionalization afforded fourteen neutral and cationic doubly bridged chiral trityl derivatives, including sulfoxide, sulfone, and sulfoximine congeners. X-ray diffraction revealed that the longer C–S bonds enforce a markedly puckered six-membered sulfur heterocycle, increasing both helical pitch and curvature relative to oxygen- and nitrogen-bridged analogues. The sulfur-containing carbocations are more electrophilic than their oxygen analogues, as demonstrated by lower pKR+ values (minimum +7.44). Combined electrochemical and optical measurements, together with DFT calculations, show that sulfur simultaneously destabilizes the HOMO and stabilizes the LUMO, thereby narrowing the electronic gap. This effect produces pronounced bathochromic shifts, with absorption extending to 636 nm and emission reaching 688 nm. In contrast, neutral azathia derivatives display large Stokes shifts of up to 4823 cm-1, consistent with substantial excited-state structural relaxation. Selective sulfur oxidation provides an orthogonal tuning element, inducing unexpectedly large blue shifts of up to 66 nm in absorption and 124 nm in emission. CSP-HPLC resolution enabled ECD and CPL studies, including a rare bisignate CPL response consistent with dual-state emission. Remarkably, sulfur-bridged cations racemize more readily than their oxygen and nitrogen analogues despite their more distorted helices (ΔG‡(300K) 26.0-28.4 kcal⸱mol–1); kinetic and DFT data support a nucleophile-assisted pathway in line with the enhanced electrophilicity. These results establish sulfur bridging as a powerful, multifaceted design strategy for tunable chiral red-emissive helicenes.

Organizational unit: Laboratory of Professor Jérôme Lacour

Type: Dataset

DOI: 10.26037/yareta:sochtyjvqjahvmp5fue4xyvcbi

License: Creative Commons Attribution 4.0 International

Publication date

24/06/2026

Retention date21/06/2036

Access levelPublic

SensitivityBlue

Contract on the use of data

License

Contributors

Chignac, Aurélien

Monti, Caterina

Pescitelli, Gennaro

Files

Quality (0 Reviews)
Usefulness (0 Reviews)

    
      <?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<datacite:resource xmlns:premis="http://www.loc.gov/premis/v3" xmlns:mets="http://www.loc.gov/METS/" xmlns:datacite="http://datacite.org/schema/kernel-4" xmlns:dlcm="http://www.dlcm.ch/dlcm/v3" xmlns:fits="http://hul.harvard.edu/ois/xml/ns/fits/fits_output" xmlns:xlink="http://www.w3.org/1999/xlink">
    <datacite:identifier identifierType="DOI">10.26037/yareta:sochtyjvqjahvmp5fue4xyvcbi</datacite:identifier>
    <datacite:creators>
        <datacite:creator>
            <datacite:creatorName nameType="Personal">Chignac, Aurélien</datacite:creatorName>
            <datacite:givenName>Aurélien</datacite:givenName>
            <datacite:familyName>Chignac</datacite:familyName>
        </datacite:creator>
        <datacite:creator>
            <datacite:creatorName nameType="Personal">Besnard, Céline</datacite:creatorName>
            <datacite:givenName>Céline</datacite:givenName>
            <datacite:familyName>Besnard</datacite:familyName>
            <datacite:nameIdentifier xsi:type="datacite:nameIdentifier" nameIdentifierScheme="ORCID" schemeURI="https://orcid.org/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">https://orcid.org/0000-0001-5699-9675</datacite:nameIdentifier>
        </datacite:creator>
        <datacite:creator>
            <datacite:creatorName nameType="Personal">Monti, Caterina</datacite:creatorName>
            <datacite:givenName>Caterina</datacite:givenName>
            <datacite:familyName>Monti</datacite:familyName>
        </datacite:creator>
        <datacite:creator>
            <datacite:creatorName nameType="Personal">Zinna, Francesco</datacite:creatorName>
            <datacite:givenName>Francesco</datacite:givenName>
            <datacite:familyName>Zinna</datacite:familyName>
            <datacite:nameIdentifier xsi:type="datacite:nameIdentifier" nameIdentifierScheme="ORCID" schemeURI="https://orcid.org/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">https://orcid.org/0000-0002-6331-6219</datacite:nameIdentifier>
        </datacite:creator>
        <datacite:creator>
            <datacite:creatorName nameType="Personal">Pescitelli, Gennaro</datacite:creatorName>
            <datacite:givenName>Gennaro</datacite:givenName>
            <datacite:familyName>Pescitelli</datacite:familyName>
        </datacite:creator>
        <datacite:creator>
            <datacite:creatorName nameType="Personal">Lacour, Jérôme</datacite:creatorName>
            <datacite:givenName>Jérôme</datacite:givenName>
            <datacite:familyName>Lacour</datacite:familyName>
            <datacite:nameIdentifier xsi:type="datacite:nameIdentifier" nameIdentifierScheme="ORCID" schemeURI="https://orcid.org/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">https://orcid.org/0000-0001-6247-8059</datacite:nameIdentifier>
        </datacite:creator>
    </datacite:creators>
    <datacite:titles>
        <datacite:title>Sulfur Bridged Cationic and Neutral [6]Helicenes – Chiral Trityls with Property and Stability Twists</datacite:title>
    </datacite:titles>
    <datacite:publisher publisherIdentifier="https://ror.org/01swzsf04" publisherIdentifierScheme="ROR" schemeURI="https://ror.org/">Université de Genève, Yareta</datacite:publisher>
    <datacite:publicationYear>2026</datacite:publicationYear>
    <datacite:resourceType resourceTypeGeneral="Dataset">Dataset</datacite:resourceType>
    <datacite:contributors>
        <datacite:contributor contributorType="ResearchGroup">
            <datacite:contributorName nameType="Organizational">[acac4008-69e9-45cf-ac63-a1752ec63ade] Laboratory of Professor Jérôme Lacour</datacite:contributorName>
            <datacite:affiliation xsi:type="datacite:affiliation" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">[UNIGE-Sciences] Université de Genève - Faculté des Sciences</datacite:affiliation>
            <datacite:affiliation xsi:type="datacite:affiliation" affiliationIdentifier="https://ror.org/01swzsf04" affiliationIdentifierScheme="ROR" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">[UNIGE] Université de Genève</datacite:affiliation>
        </datacite:contributor>
        <datacite:contributor contributorType="ProjectManager">
            <datacite:contributorName nameType="Personal">Lacour, Jérôme</datacite:contributorName>
        </datacite:contributor>
    </datacite:contributors>
    <datacite:dates>
        <datacite:date dateType="Issued">2026-06-24T00:00:00Z</datacite:date>
        <datacite:date dateType="Collected">2020-09-01T00:00:00Z/2025-06-30T00:00:00Z</datacite:date>
        <datacite:date dateType="Created">2026-06-24T09:51:36.928065Z</datacite:date>
        <datacite:date dateType="Updated">2026-10-02T12:39:33.045674Z</datacite:date>
        <datacite:date dateType="Accepted">2026-10-02T12:39:32.229257763Z</datacite:date>
    </datacite:dates>
    <datacite:alternateIdentifiers>
        <datacite:alternateIdentifier alternateIdentifierType="ARK">ark:64642/rt9sochtyjvqjahvmp5fue4xyvcbi</datacite:alternateIdentifier>
    </datacite:alternateIdentifiers>
    <datacite:relatedIdentifiers/>
    <datacite:formats>
        <datacite:format>text/plain</datacite:format>
        <datacite:format>application/octet-stream</datacite:format>
        <datacite:format>text/xml</datacite:format>
        <datacite:format>inode/x-empty</datacite:format>
        <datacite:format>application/pdf</datacite:format>
        <datacite:format>image/png</datacite:format>
        <datacite:format>audio/mpeg</datacite:format>
        <datacite:format>application/x-dosexec</datacite:format>
        <datacite:format>application/vnd.openxmlformats-officedocument.spreadsheetml.sheet</datacite:format>
        <datacite:format>application/vnd.ms-excel</datacite:format>
        <datacite:format>application/vnd.openxmlformats-officedocument.wordprocessingml.document</datacite:format>
    </datacite:formats>
    <datacite:rightsList>
        <datacite:rights rightsURI="https://www.dlcm.ch/access-level/final">PUBLIC</datacite:rights>
        <datacite:rights rightsURI="https://www.dlcm.ch/data-tag">BLUE</datacite:rights>
        <datacite:rights rightsURI="https://www.dlcm.ch/data-use-policy">LICENSE</datacite:rights>
        <datacite:rights rightsURI="https://creativecommons.org/licenses/by/4.0/" rightsIdentifier="CC-BY-4.0" rightsIdentifierScheme="SPDX">Creative Commons Attribution 4.0 International</datacite:rights>
    </datacite:rightsList>
    <datacite:descriptions>
        <datacite:description descriptionType="Abstract" xml:lang="en">Replacing oxygen and nitrogen by sulfur atoms in cationic [6]helicenes alters their molecular shape, electronic structure, absorption, emission, chemical and configurational stability. A modular synthetic route combining early sulfur incorporation, heteroatom-bridge diversification, and late-stage functionalization afforded fourteen neutral and cationic doubly bridged chiral trityl derivatives, including sulfoxide, sulfone, and sulfoximine congeners. X-ray diffraction revealed that the longer C–S bonds enforce a markedly puckered six-membered sulfur heterocycle, increasing both helical pitch and curvature relative to oxygen- and nitrogen-bridged analogues. The sulfur-containing carbocations are more electrophilic than their oxygen analogues, as demonstrated by lower pKR+ values (minimum +7.44). Combined electrochemical and optical measurements, together with DFT calculations, show that sulfur simultaneously destabilizes the HOMO and stabilizes the LUMO, thereby narrowing the electronic gap. This effect produces pronounced bathochromic shifts, with absorption extending to 636 nm and emission reaching 688 nm. In contrast, neutral azathia derivatives display large Stokes shifts of up to 4823 cm-1, consistent with substantial excited-state structural relaxation. Selective sulfur oxidation provides an orthogonal tuning element, inducing unexpectedly large blue shifts of up to 66 nm in absorption and 124 nm in emission. CSP-HPLC resolution enabled ECD and CPL studies, including a rare bisignate CPL response consistent with dual-state emission. Remarkably, sulfur-bridged cations racemize more readily than their oxygen and nitrogen analogues despite their more distorted helices (ΔG‡(300K) 26.0-28.4 kcal⸱mol–1); kinetic and DFT data support a nucleophile-assisted pathway in line with the enhanced electrophilicity. These results establish sulfur bridging as a powerful, multifaceted design strategy for tunable chiral red-emissive helicenes.</datacite:description>
    </datacite:descriptions>
    <datacite:fundingReferences/>
</datacite:resource>