TY  - JOUR
A1  - Yu, Mingfeng
A1  - Ast, Sandra
A1  - Yu, Qun
A1  - Lo, Anthony T. S.
A1  - Flehr, Roman
A1  - Todd, Matthew H.
A1  - Rutledge, Peter J.
T1  - Incorporating a piperidinyl group in the fluorophore extends the fluorescence lifetime of click-derived cyclam-naphthalimide conjugates
JF  - PLoS one
N2  - Ligands incorporating a tetraazamacrocycle receptor, a 'click'-derived triazole and a 1,8-naphthalimide fluorophore have proven utility as probes for metal ions. Three new cyclam-based molecular probes are reported, in which a piperidinyl group has been introduced at the 4-position of the naphthalimide fluorophore. These compounds have been synthesized using the copper(I)-catalyzed azide-alkyne Huisgen cycloaddition and their photophysical properties studied in detail. The alkylamino group induces the expected red-shift in absorption and emission spectra relative to the simple naphthalimide derivatives and gives rise to extended fluorescence lifetimes in aqueous buffer. The photophysical properties of these systems are shown to be highly solvent-dependent. Screening the fluorescence responses of the new conjugates to a wide variety of metal ions reveals significant and selective fluorescence quenching in the presence of copper(II), yet no fluorescence enhancement with zinc(II) as observed previously for the simple naphthalimide derivatives. Reasons for this different behaviour are proposed. Cytotoxicity testing shows that these new cyclam-triazole-dye conjugates display little or no toxicity against either DLD-1 colon carcinoma cells or MDA-MB-231 breast carcinoma cells, suggesting a potential role for these and related systems in biological sensing applications.
Y1  - 2014
U6  - https://doi.org/10.1371/journal.pone.0100761
SN  - 1932-6203
VL  - 9
IS  - 7
PB  - PLoS
CY  - San Fransisco
ER  - 
TY  - JOUR
A1  - Wong, Joseph K. -H.
A1  - Ast, Sandra
A1  - Yu, Mingfeng
A1  - Flehr, Roman
A1  - Counsell, Andrew J.
A1  - Turner, Peter
A1  - Crisologo, Patrick
A1  - Todd, Matthew H.
A1  - Rutledge, Peter J.
T1  - Synthesis and Evaluation of 1,8-Disubstituted-Cyclam/Naphthalimide Conjugates as Probes for Metal Ions
JF  - ChemistryOpen : including thesis treasury
N2  - Fluorescent molecular probes for metal ions have a raft of potential applications in chemistry and biomedicine. We report the synthesis and photophysical characterisation of 1,8-disubstituted-cyclam/naphthalimide conjugates and their zinc complexes. An efficient synthesis of 1,8-bis-(2-azidoethyl)cyclam has been developed and used to prepare 1,8-disubstituted triazolyl-cyclam systems, in which the pendant group is connected to triazole C4. UV/Vis and fluorescence emission spectra, zinc binding experiments, fluorescence quantum yield and lifetime measurements and pH titrations of the resultant bis-naphthalimide ligand elucidate a complex pattern of photophysical behaviour. Important differences arise from the inclusion of two fluorophores in the one probe and from the variation of triazole substitution pattern (dye at C4 vs. N1). Introducing a second fluorophore greatly extends fluorescence lifetimes, whereas the altered substitution pattern at the cyclam amines exerts a major influence on fluorescence output and metal binding. Crystal structures of two key zinc complexes evidence variations in triazole coordination that mirror the solution-phase behaviour of these systems.
KW  - chromophores
KW  - click triazoles
KW  - fluorescent probes
KW  - macrocyclic compounds
KW  - photophysics
Y1  - 2016
U6  - https://doi.org/10.1002/open.201600010
SN  - 2191-1363
VL  - 5
SP  - 375
EP  - 385
PB  - Wiley-VCH
CY  - Weinheim
ER  -