A Luminescent NOTA-Based Terbium(III) “Turn-Off” Sensor for Copper

Abstract

A bimacrocyclic luminescent terbium(III) sensor is reported for the selective 'turn-off' detection of Cu 2+ ions in aqueous solutions. The current sensor differentiates from previous sensors in that it offers the use of 1) time-gated luminescence detection to remove background signal, 2) a longer excitation wavelength of up to 350 nm for increased biocompatibility, and 3) a practically irreversible detection as a form of probing Cu 2+ ions with an extremely low limit of detection of about 1.7 nM. Synopsis: The detection of copper ions in aqueous solutions is an active and growing research field relevant to bioanalyses and environmental sampling. There is a high demand for sensitive and selective probes for copper in biological environment including intracellular monitoring. This would allow for a better understanding of the bivalent role of copper in the human body. Herein, we report a bimacrocyclic luminescent terbium(III) sensor for the selective 'turn-off' detection of Cu 2+ ions in aqueous solutions.

Innovative Multipodal Ligands Derived from Tröger's Bases for the Sensitization of Lanthanide(III) Luminescence

“…The 1 HNMR spectra showi ne very case the typical pattern of the TB diazocinic core in the 3.5-5.0 ppm region, with as inglet originating from the bridgehead methylene between the two doublets of the inequivalent exo and endo protons of the diazocinic methylene groups ( 2 J % 17 Hz). Furthermore, the Ugi products were identified by the presence of the diagnostic signal of the methylene NCH 2 CON that derives from the formaldehydec arbon atom.T his signal is particularly easy to observe in 2D HSQC spectra as ac ross peak at around4ppm for 1 Ha nd 55 ppm for 13 C.…”

“…[7] One pertinent strategy to achieve this goal is to use ligand systems that will achieve the complete coordination of Ln III ions, thereby preventing theb indingo fs olvent molecules, such as water, to theL n III .I nt hisw ork, flexible podand ligandsw ered esigned, synthesized, andderivatized to orient theirbinding unitsaround theLn III iontoachieve efficientcoordination andthusprotection of the ion from their chemical environment. [1,6,[8][9][10][11][12][13][14] Podands possess the advantages of synthetic accessibility and versatility,a nd have been used for the grafting of functionalized pendant arms onto ac onvenientf ramework such as as mall aromatic ring, in as imilarf ashion to the attachment to macrocycles such as cyclen derivatives or calixarenes. [4,5,14,15] In view of the eight or more coordinations ites of Ln III ions, this strategyi sp articularly suitable for the design of ligandsw ith bi-or tridentate pendant arms,a sr equired for the complete and efficient coordination of Ln III ions.…”

“…One pertinent strategy to achieve this goal is to use ligand systems that will achieve the complete coordination of Ln III ions, thereby preventing the binding of solvent molecules, such as water, to the Ln III . In this work, flexible podand ligands were designed, synthesized, and derivatized to orient their binding units around the Ln III ion to achieve efficient coordination and thus protection of the ion from their chemical environment [1, 6, 8–14] …”

A Six‐Armed Phenhomazine Ligand with a Potential “Turn‐Off” Copper(II) Sensing Capability through Terbium(III) Luminescence Quenching

“…The working principle of most of these sensors is based on the quenching of the lanthanide(III) luminescence by the presence of Cu II ions, through an electron or energy transfer mechanism to/from the excited lumophore and through paramagnetic effects . These processes, when combined with the unique optical properties of lanthanide(III) ions, that is, sharp emission bands, large energy difference between absorption and emission bands, and long luminescence lifetimes, allow the design of “turn‐off” sensors, in which the presence of copper(II) ions is detected through the diminution of the lanthanide(III) luminescence signal . Moreover, some of the lanthanide(III) ions, namely terbium(III) and europium(III), emit in the visible region of the electromagnetic spectrum, and can thus be easily recognized by the naked eye …”

A terbium(iii) luminescent ATCUN-based peptide sensor for selective and reversible detection of copper(ii) in biological media

“…the high selectivity for Cu 2+ , the appropriate affinity and the reversibility. [30][31][32][33][34][35][36] In this article, we present the design of a turn-off luminescent peptide for Cu 2+ , combining the selectivity and suitable affinity of the ATCUN motif with the long-lifetime emission of the lanthanide Tb 3+ , and we prove its suitability for Cu 2+ sensing in biological-like media via time-resolved luminescence detection. As the low extinction coefficients of the Laporte-forbidden 4f-4f transitions impair the efficient excitation of Ln 3+ ions, it is necessary to resort to the so-called "antenna effect", i.e.…”