Fluorescence Chemosensory Determination of Cu2+ Using a New Rhodamine–Morpholine Conjugate

Abstract

Abstract:A new rhodamine-B carbonyl-morpholine derivative (denoted as RECM) was prepared by a two-step synthesis procedure. The employed method allowed a lactam ring development of rhodamine-B and ethylenediamine to demonstrate a facile amide bond formation. The obtained RECM was confirmed by 1 H NMR, 13 C NMR, and mass spectrometry analysis. RECM was formed to detect copper ion (Cu 2+ ) due to its problematic toxicity features in aquatic ecosystems. It showed a high selectivity toward Cu 2+ in comparison with some environmentally relevant alkali, alkaline earth, and transition metal cations at 50 µM in acetonitrile. Moreover, non-fluorescent RECM showed fluorescence intensity and UV-Vis absorbance increases in the presence of Cu 2+ with high linear dependent coefficients (R 2 = 0.964 and R 2 = 0.982 respectively) as well as a color change from colorless to pink owing to the ring opening of the rhodamine spirolactam form. Binding capability experiments presented a clear 1:1 stoichiometry of RECM-Cu 2+ complex with the binding constant (K a ) as 2.25 × 10 4 M −1 . The calculation of limits of detection (LOD) was 0.21 µM based on the linear regression method, which is below the maximum contaminant level goal (MCLG) value of Cu 2+ (1.3 ppm equals to 20.46 µM) in drinking water. These characteristics make the RECM a promising candidate for the real-time detection of toxic Cu 2+ in environmental monitoring applications.

Solvent-Regulated Fluorimetric Differentiation of Al3+ and Zn2+ Using an AIE-Active Single Sensor

“…This may be due to the strong binding tendency of Cu 2+ to replace the Al 3+ ions from the Al 3+ -bounded complex and the paramagnetic quenching properties of Cu 2+ ions. 63,64 A similar experiment for Zn 2+ with H 2 L and other competing ions in DMSO−H 2 O revealed that none of these metal ions exhibited notable fluorescence quenching except for Cu 2+ (Figure 6b).…”

“…However, a large decrease in emission intensity was found for Cu 2+ (Figure a). This may be due to the strong binding tendency of Cu 2+ to replace the Al 3+ ions from the Al 3+ -bounded complex and the paramagnetic quenching properties of Cu 2+ ions. , …”

Development of a Fluorescein-Based Probe with an “Off–On” Mechanism for Selective Detection of Copper (II) Ions and Its Application in Imaging of Living Cells

“…It is worth noting that this probe has a unique ability to recognize Cu 2+ in multi-ion coexistence solutions and shows a very intense fluorescence absorption peak at 525 nm, unlike other ions that are almost unchanged. Compared with other probes reported in the published literature [ 25 , 39 , 40 , 41 , 42 , 43 ], this probe has a relatively low detection limit and a stabilized fluorescence response at pH 6.0–9.0. In addition, through the discussion of the response mechanism between Cu 2+ and the probe, it was revealed that Cu 2+ enabled a certain reversibility of the recognition effect of the N2 probe by opening the lactam ring of the N2 probe and complexing with it in a 1:1 coordination ratio ( Figure 1 ).…”

Synthesis and fluorescent properties of some Furan‐tagged Thieno[2,3‐d]pyrimidines and Thieno[2,3‐d:4,5‐d']dipyrimidines

“…Additionally; thienopyrimidine scaffolds with appropriate absorption and emission wavelengths act as fluorophores. [13,14] These fluorescent organic compounds are widely used in bioprobes, [15,16] organic light-emitting diodes, [17,18] photosensitizers, [19] and optical chemosensors, [20][21][22] which become important tools in analytical chemistry and medicine. [23][24][25] Moreover, some fluorescent compounds are utilized in studying the environmental pollution.…”