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A colorimetric chemosensor for Cu²⁺ ion detection based on an iridium(III) complex.

Wang M, Leung KH, Lin S, Chan DS, Kwong DW, Leung CH, Ma DL - Sci Rep (2014)

Bottom Line: We report herein the synthesis and application of a series of novel cyclometalated iridium(III) complexes 1-3 bearing a rhodamine-linked NˆN ligand for the detection of Cu(2+) ions.Under the optimised conditions, the complexes exhibited high sensitivity and selectivity for Cu(2+) ions over a panel of other metal ions, and showed consistent performance in a pH value range of 6 to 8.Furthermore, the potential application of this system for the monitoring of Cu(2+) ions in tap water or natural river water samples was demonstrated.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemistry, Hong Kong Baptist University, Kowloon Tong, Hong Kong, China.

ABSTRACT
We report herein the synthesis and application of a series of novel cyclometalated iridium(III) complexes 1-3 bearing a rhodamine-linked NˆN ligand for the detection of Cu(2+) ions. Under the optimised conditions, the complexes exhibited high sensitivity and selectivity for Cu(2+) ions over a panel of other metal ions, and showed consistent performance in a pH value range of 6 to 8. Furthermore, the potential application of this system for the monitoring of Cu(2+) ions in tap water or natural river water samples was demonstrated.

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Absorption spectra of 5 μM of complexes (a) 1, (c) 2 and (e) 3 in the presence of increasing concentrations of Cu2+ ion (1:1 ACN-Tris, pH 7.0). Absorbance of complexes (b) 1, (d) 2 and (f) 3 at 555 nm vs. [Cu2+]. Inset: linear plot of the change in absorbance of the system vs. [Cu2+].
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f2: Absorption spectra of 5 μM of complexes (a) 1, (c) 2 and (e) 3 in the presence of increasing concentrations of Cu2+ ion (1:1 ACN-Tris, pH 7.0). Absorbance of complexes (b) 1, (d) 2 and (f) 3 at 555 nm vs. [Cu2+]. Inset: linear plot of the change in absorbance of the system vs. [Cu2+].

Mentions: To optimize the performance of the sensor, the choice of organic solvent, aqueous buffer and overall solvent composition were investigated. The absorption increase of complexes 1–3 in response to Cu2+ ions was highest with acetonitrile (ACN) compared to dimethyl sulfoxide (DMSO), tetrahydrofuran (THF) or N,N-dimethylformamide (DMF) (Figure S3). Additionally, complexes 1–3 displayed similar responses to Cu2+ ions in buffer systems containing 90, 70 or 50% of acetonitrile (Figure S4). However, the absorption of the complexes was seen to decrease by 30-50% when 30% of acetonitrile was used (Figure S4). Hence, 50% of acetonitrile was considered optimal for further study. We also found that the use of 2-amino-2-hydroxymethyl-propane-1,3-diol (Tris), 2-(N-morpholino)ethanesulfonic acid (MES) and 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES) buffer gave similar performances, whereas the use of phosphate buffer resulted in a 25% decrease in absorption intensity of the complexes in response to Cu2+ ions (Figure S5). Moreover, the optimal concentration of Tris buffer was determined to be 10 mM (Figure S6). After optimization of the assay conditions, we performed an absorption titration experiment to investigate the absorption response of complexes 1–3 to Cu2+ ions. Encouragingly, the absorption of complexes 1–3 was enhanced as the concentration of Cu2+ ions increased (Figure 2a, c, e). Saturation of the absorbance value was reached at 35 μM of Cu2+ ions for all three complexes. Complexes 1 and 3 exhibited a linear range of detection for Cu2+ ions from 10 nM to 8 μM (R2 = 0.99), while complex 2 displayed a linear range of detection for Cu2+ ions from 10 nM to 6 μM (Figure 2b, d, f). The detection limit of complexes 1–3 for Cu2+ ions was estimated to be 4.5, 5.2 and 4.9 nM using the 3σ criterion, indicating that these complexes were highly sensitive for Cu2+ ions. Additionally, the color change of the solution from colorless to pink occurred within 10 s upon the addition of Cu2+ ions, suggesting that complexes 1–3 could potentially serve as simple and rapid ‘naked-eye’ indicators for Cu2+ ions (Figure 3a).


A colorimetric chemosensor for Cu²⁺ ion detection based on an iridium(III) complex.

Wang M, Leung KH, Lin S, Chan DS, Kwong DW, Leung CH, Ma DL - Sci Rep (2014)

Absorption spectra of 5 μM of complexes (a) 1, (c) 2 and (e) 3 in the presence of increasing concentrations of Cu2+ ion (1:1 ACN-Tris, pH 7.0). Absorbance of complexes (b) 1, (d) 2 and (f) 3 at 555 nm vs. [Cu2+]. Inset: linear plot of the change in absorbance of the system vs. [Cu2+].
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4210870&req=5

f2: Absorption spectra of 5 μM of complexes (a) 1, (c) 2 and (e) 3 in the presence of increasing concentrations of Cu2+ ion (1:1 ACN-Tris, pH 7.0). Absorbance of complexes (b) 1, (d) 2 and (f) 3 at 555 nm vs. [Cu2+]. Inset: linear plot of the change in absorbance of the system vs. [Cu2+].
Mentions: To optimize the performance of the sensor, the choice of organic solvent, aqueous buffer and overall solvent composition were investigated. The absorption increase of complexes 1–3 in response to Cu2+ ions was highest with acetonitrile (ACN) compared to dimethyl sulfoxide (DMSO), tetrahydrofuran (THF) or N,N-dimethylformamide (DMF) (Figure S3). Additionally, complexes 1–3 displayed similar responses to Cu2+ ions in buffer systems containing 90, 70 or 50% of acetonitrile (Figure S4). However, the absorption of the complexes was seen to decrease by 30-50% when 30% of acetonitrile was used (Figure S4). Hence, 50% of acetonitrile was considered optimal for further study. We also found that the use of 2-amino-2-hydroxymethyl-propane-1,3-diol (Tris), 2-(N-morpholino)ethanesulfonic acid (MES) and 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES) buffer gave similar performances, whereas the use of phosphate buffer resulted in a 25% decrease in absorption intensity of the complexes in response to Cu2+ ions (Figure S5). Moreover, the optimal concentration of Tris buffer was determined to be 10 mM (Figure S6). After optimization of the assay conditions, we performed an absorption titration experiment to investigate the absorption response of complexes 1–3 to Cu2+ ions. Encouragingly, the absorption of complexes 1–3 was enhanced as the concentration of Cu2+ ions increased (Figure 2a, c, e). Saturation of the absorbance value was reached at 35 μM of Cu2+ ions for all three complexes. Complexes 1 and 3 exhibited a linear range of detection for Cu2+ ions from 10 nM to 8 μM (R2 = 0.99), while complex 2 displayed a linear range of detection for Cu2+ ions from 10 nM to 6 μM (Figure 2b, d, f). The detection limit of complexes 1–3 for Cu2+ ions was estimated to be 4.5, 5.2 and 4.9 nM using the 3σ criterion, indicating that these complexes were highly sensitive for Cu2+ ions. Additionally, the color change of the solution from colorless to pink occurred within 10 s upon the addition of Cu2+ ions, suggesting that complexes 1–3 could potentially serve as simple and rapid ‘naked-eye’ indicators for Cu2+ ions (Figure 3a).

Bottom Line: We report herein the synthesis and application of a series of novel cyclometalated iridium(III) complexes 1-3 bearing a rhodamine-linked NˆN ligand for the detection of Cu(2+) ions.Under the optimised conditions, the complexes exhibited high sensitivity and selectivity for Cu(2+) ions over a panel of other metal ions, and showed consistent performance in a pH value range of 6 to 8.Furthermore, the potential application of this system for the monitoring of Cu(2+) ions in tap water or natural river water samples was demonstrated.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemistry, Hong Kong Baptist University, Kowloon Tong, Hong Kong, China.

ABSTRACT
We report herein the synthesis and application of a series of novel cyclometalated iridium(III) complexes 1-3 bearing a rhodamine-linked NˆN ligand for the detection of Cu(2+) ions. Under the optimised conditions, the complexes exhibited high sensitivity and selectivity for Cu(2+) ions over a panel of other metal ions, and showed consistent performance in a pH value range of 6 to 8. Furthermore, the potential application of this system for the monitoring of Cu(2+) ions in tap water or natural river water samples was demonstrated.

Show MeSH
Related in: MedlinePlus