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Fluorescent functionalised naphthalimides and their Au(I)–NHC complexes for potential use in cellular bioimaging

Fluorescent functionalised naphthalimides and their Au(I)–NHC complexes for potential use in cellular bioimaging
Fluorescent functionalised naphthalimides and their Au(I)–NHC complexes for potential use in cellular bioimaging
A series of cationic, dihydroimidazolinium-functionalized 1,8-naphthalimide fluorophores have been isolated as their hexafluorophosphate salts, [HL]PF6. These pro-ligands react with [AuCl(tht)] in the presence of base to form N-heterocyclic carbene (NHC) complexes, [AuCl(L)]. Two X-ray structures represent a pro-ligand and complex pairing: the latter reveals the two-coordinate linear geometry of the NHC–Au(I) species, as well as intermolecular interactions supported by both ligand π–π stacking and a weak aurophilic interaction of 3.3205(6) Å. The luminescence properties of the pro-ligands and complexes are dominated by the ICT character of the substituted fluorophore at ca. 500 nm, which is further modulated via functionalization at the 4-position of the naphthalimide. Cytotoxicity assessments were performed for all [HL]PF6 and [AuCl(L)] species against LOVO, MCF-7, A549 and PC3 cell lines; added lipophilicity seems to correlate with increased cytotoxicity. Confocal fluorescence microscopy was undertaken on a selected [HL]PF6 and [AuCl(L)] species and showed that the intracellular distribution is dependent upon the specific ligand structure. More detailed co-localisation studies show that selected examples present a predominant lysosomal staining pattern. FLIM studies exemplified the applicability of these probes, and secondly suggest that fluorescence lifetime could be used to provide information on the integrity of the complex and thus liberation of gold in a biological environment.
0300-9246
Groves, Lara M.
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Williams, Catrin F.
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Hayes, Anthony J.
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Ward, Benjamin D.
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Isaacs, Marc D.
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Symonds, Nadine O.
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Lloyd, David
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Horton, Peter N.
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Coles, Simon J.
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Pope, Simon J.A.
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Groves, Lara M.
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Williams, Catrin F.
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Hayes, Anthony J.
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Ward, Benjamin D.
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Isaacs, Marc D.
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Symonds, Nadine O.
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Lloyd, David
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Horton, Peter N.
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Coles, Simon J.
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Pope, Simon J.A.
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Groves, Lara M., Williams, Catrin F., Hayes, Anthony J., Ward, Benjamin D., Isaacs, Marc D., Symonds, Nadine O., Lloyd, David, Horton, Peter N., Coles, Simon J. and Pope, Simon J.A. (2018) Fluorescent functionalised naphthalimides and their Au(I)–NHC complexes for potential use in cellular bioimaging. Dalton Transactions. (doi:10.1039/c8dt04069a).

Record type: Article

Abstract

A series of cationic, dihydroimidazolinium-functionalized 1,8-naphthalimide fluorophores have been isolated as their hexafluorophosphate salts, [HL]PF6. These pro-ligands react with [AuCl(tht)] in the presence of base to form N-heterocyclic carbene (NHC) complexes, [AuCl(L)]. Two X-ray structures represent a pro-ligand and complex pairing: the latter reveals the two-coordinate linear geometry of the NHC–Au(I) species, as well as intermolecular interactions supported by both ligand π–π stacking and a weak aurophilic interaction of 3.3205(6) Å. The luminescence properties of the pro-ligands and complexes are dominated by the ICT character of the substituted fluorophore at ca. 500 nm, which is further modulated via functionalization at the 4-position of the naphthalimide. Cytotoxicity assessments were performed for all [HL]PF6 and [AuCl(L)] species against LOVO, MCF-7, A549 and PC3 cell lines; added lipophilicity seems to correlate with increased cytotoxicity. Confocal fluorescence microscopy was undertaken on a selected [HL]PF6 and [AuCl(L)] species and showed that the intracellular distribution is dependent upon the specific ligand structure. More detailed co-localisation studies show that selected examples present a predominant lysosomal staining pattern. FLIM studies exemplified the applicability of these probes, and secondly suggest that fluorescence lifetime could be used to provide information on the integrity of the complex and thus liberation of gold in a biological environment.

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Accepted/In Press date: 21 November 2018
e-pub ahead of print date: 19 December 2018

Identifiers

Local EPrints ID: 427166
URI: http://eprints.soton.ac.uk/id/eprint/427166
ISSN: 0300-9246
PURE UUID: 69885117-e0d7-4fae-9c3e-26217c3b39da
ORCID for Peter N. Horton: ORCID iD orcid.org/0000-0001-8886-2016
ORCID for Simon J. Coles: ORCID iD orcid.org/0000-0001-8414-9272

Catalogue record

Date deposited: 04 Jan 2019 17:30
Last modified: 26 Nov 2021 02:43

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Contributors

Author: Lara M. Groves
Author: Catrin F. Williams
Author: Anthony J. Hayes
Author: Benjamin D. Ward
Author: Marc D. Isaacs
Author: Nadine O. Symonds
Author: David Lloyd
Author: Peter N. Horton ORCID iD
Author: Simon J. Coles ORCID iD
Author: Simon J.A. Pope

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