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[Display omitted] • Highly fluorescent N, B-doped CNDs discerning interactions with Fe(II) and Fe(III). • The "urn-Off" optical probe relies on a concentration-dependent fluorescence decrease. • The N, B-doped CNDs are selective towards Fe(II) ions in the presence of other metals. • The CNDs can monitor Fe(II) presence in living cells by fluorescent imaging. The interactions between metal ions and fluorescent probes are fundamentals for discerning the metal ions. Co-doped carbon nanodots (CNDs) have demonstrated the capacity to optically detect a wide variety of targets, including metal ions. In this work, the quenching of highly fluorescent, nitrogen (N) and boron (B) co-doped CNDs by Fe(II) ions was discovered and employed to differentiate Fe2+ in water samples and live cells. The fluorescence of the N,B-CNDs was quenched in a concentration-dependent manner with a need of very short reaction time (30 s), and the CNDs show good selectivity towards Fe(II) ions relative to other metal ions including Fe(III). The limit of detection (LOD) was calculated as 1.8 nM and the linear response range was 7 nM to 1 μM. The recovery percentage was determined to be 97%, 101%, and 103% for spiked Fe(II) concentrations of 31, 125, and 1000 nM, respectively, in tap water. The N,B-CNDs were able to monitor the presence of Fe(II) in living cells using the optical imaging of Fe(II) ions, and the quenching in cells was completed within one hour. Regarding the quenching mechanism, the photoinduced electron transfer (PET) procedure is proposed with support of cyclic voltammetry study on the CNDs upon addition of Fe(II). Overall, the N,B-CNDs promise as optical probes for the detection of Fe2+ in water and living cells, and demonstrated a satisfactory level of sensitivity and selectivity. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Naphthalene dianhydride based novel probe R1 useful for the detection of Fe+3. • The performance of probe R1 over the other di/trivalent ions. • The PET mechanism on fluorescent turn-on cell permeable probe. • The efficacy of R1 towards live-cells. Abstract A green emissive PET operating fluorescent turn-on cell permeable novel probe R1 has been successfully developed and utilized for the detection of Fe+3 in the pure aqueous system at sub-nanomolar level. Moreover, probe R1 demonstrate highly sensitive and selective towards Fe+3 over the other divalent and trivalent metal ions and was established by using fluorescence spectroscopy. The efficiency and aid of R1 was demonstrated by the fluorescence imaging of captured Fe+3 within Pollen grains by using fluorescence microscopy. These results indicate that, this is the first fluorescent turn-on PET probe to detect sub-nanomolar Fe+3 in the pure aqueous system and in cellular level. [ABSTRACT FROM AUTHOR]

A new, easily accessible “off-on-off” colorimetric and fluorescent probes are designed and synthesized. It displayed highly selective and sensitive detection towards Cu 2+ ion without having any interference from other competitive metal ions. The examined UV–vis and fluorescence spectral changes are caused by the operation if the ligand to metal charge transfer (LMCT) and chelation enhanced fluorescence effect (CHEF) in the presence of Cu 2+ to the present probes. Besides, the density functional theory (DFT) calculations have been theoretically supported the photophysical changes. These probes are potentially applied in an analytical application for detecting the trace amount of Cu 2+ ions in real water samples. Furthermore, these probes are successfully applied for fluorescence imaging of Cu 2+ in HeLa cells. Finally, the use of test strips based on these probes is fabricated, which could act as a convenient and efficient Cu 2+ test kit in solution medium and supported on solid medium (silica). [ABSTRACT FROM AUTHOR]

A novel fluorescent BODIPY-rhodamine dyad probe that operates based on through bond energy transfer (TBET) phenomenon has been synthesized and its application in the detection of biologically relevant metal ions is explored. Among several metal ions, the probe selectively responds to the addition of trivalent metal ions (Al 3+ , Cr 3+ and Fe 3+ ) through its signature absorbance and fluorescence characteristics and permits their ratiometric detection. The trivalent metal ion detection ability of the probe is unaffected with the presence of other commonly coexistent ions. The probe is highly sensitive and it can detect the trivalent metal ions even at ppb level concentrations. The probe is nontoxic under the experimental conditions, cell permeable and useful for the imaging of Al 3+ , Cr 3+ and Fe 3+ ions present in W138 (normal lung fibroblast) cells. [ABSTRACT FROM AUTHOR]

An effective morpholine-type naphthalimide chemsensor, N- p -chlorophenyl-4-(2-aminoethyl)morpholine-1,8-naphthalimide (CMN) has been developed as a lysosome-targeted fluorometric sensor for trivalent metal ions (Fe3+, Al3+ and Cr3+). Upon the addition of Fe3+, Al3+ or Cr3+ ions, the probe CMN showed an evident naked-eye color changes which pale yellow solution of CMN turned deepened and it displayed turn-on fluorescence response in methanol. CMN showed a significant selective and sensitive toward Fe3+, Al3+ or Cr3+ ions, while there was no obvious behavior to other monovalent or divalent metal ions from the UV–vis and fluorescence spectrum. Based on the Job's plot analyses the 1:1 coordination mode of CMN with Fe3+, Al3+ or Cr3+ was proposed. The limit of detection (LOD) observed were 0.65, 0.69 and 0.68 μM for Fe3+, Al3+ and Cr3+ ions, respectively. The N-atom of morpholine directly involved in complex formation, CMN emitted fluorescence through inhibition of photoinduced electron transfer (PET). This probe exhibited excellent imaging ability for Fe3+, Al3+and Cr3+ ions in living cells with low cytotoxicity. Significantly, the cellular confocal microscopic research indicated that the lysosome-targeted group of morpholine moiety was introduced which realized the capability of imaging lysosomal trivalent metal ions in living cells for the first time. Unlabelled Image • A "turn–on" chemosensor for trivalent cations was developed. • The probe showed naked-eye color changes for trivalent cations detection. • The logic gate at molecular level was anticipated. • The probe was suitable for imaging lysosomal trivalent cations in living cells. [ABSTRACT FROM AUTHOR]