A new ferrocene–anthracene dyad for dual-signaling sensing of Cu(II) and Hg(II)

Luminescent Pyrene-based Schiff base Receptor for Hazardous Mercury(II) Detection Demonstrated by Cell Imaging and Test Strip

Qualitative and quantitative analysis of mercury at concentration levels as low as parts per billion (ppb) is a basic and practical concern. The vast majority of research in this field has centered on the development of potent chemosensor to monitor mercuric (Hg²⁺) ions. Mercury exists in three oxidation states, + 2, + 1 and 0, all of which are highly poisonous. In this study, (N¹E,N²E)-N¹,N²-bis(pyrene-1-ylmethylene)benzene-1,2-diamine (PAPM), a novel photoluminescent sensor based on pyrene platform was synthesized. Over the tested metal ions (Cd²⁺, Co²⁺, Cu²⁺, Mg²⁺, Mn²⁺, Ni²⁺, K⁺, Na⁺, Zn²⁺, Sr²⁺, Pb²⁺, Al³⁺, Cr³⁺ and Fe³⁺) the sensor responds only to Hg²⁺ by showing high selectivity and sensitivity. After treatment with mercuric ions at room temperature, the luminescence intensity of probe was quenched at 456 nm. The quenching of fluorescence intensity of probe upon addition of mercury is due to the effect of "turn-off" chelation enhanced quenching (CHEQ) by the formation of 1:1 complex. The ESI-MS spectrum and the Job's experimental results confirm the formation of 1:1 complex between PAPM and Hg²⁺. The detection limit and association constant of sensor for mercury is computed using fluorescence titration data and were found to be 9.0 × 10^-8 M and 1.29 × 10⁵ M^-1 respectively. The practical application of sensor towards recognition of mercury(II) ions was explored through economically viable test strips and also using cell imaging studies.

A Novel Quinoline Derivative for Selective and Sensitive Visual Detection of PPB Level Cu2+ in an Aqueous Solution

Aim:

Selective and sensitive visual detection of Cu2+in aqueous solution at PPB level using easily synthesized compound.

Background:

The search for a chemosensor that can detect Cu2+ is very long owing to the fact that an optimum level of Cu2+ is required for human health and the recommended amount of Cu2+ in drinking water is set to be 1-2 mgL-1 . Thus, it is very important to detect Cu2+ even at a very low concentration to assess the associated health risks.

Objective:

We are still seeking for the easiest, cheapest, fastest and greenest sensor that can selectively, sensitively and accurately detect Cu2+ with lowest detection limit. Our objective of this work is to find one such Cu2+ sensor.

Methods:

We have synthesized a quinoline derivative following very easy synthetic procedures and characterize the compound by standard methods. For sensing study, we used steady state absorption and emission spectroscopy.

Results:

Our sensor can detect Cu2+ selectively and sensitively in aqueous solution instantaneously even in the presence of excess amount of other salts. The pale-yellow color of the sensor turns red on the addition of Cu2+ . There is no interference from other cations and anions. A 2:1 binding mechanism of the ligand with Cu2+ is proposed using Jobs plot with binding constant in the order of 109 M-2 . We calculated the LOD to be 18 ppb, which is quite low than what is permissible in drinking water.

Conclusion:

We developed a new quinoline based chemo-sensor following straightforward synthetic procedure from very cheap starting materials that can detect Cu2+ visually and instantaneously in aqueous solution with ppb level sensitivity and zero interference from other ions.

Strategic Design of a 2,6-Disubstituted Pyridine-based Probe having Hard-Soft Centers: Responsive Divergence from One Core

Alkyne is a versatile functional group in organic chemistry, and is able to undergo a wide variety of reactions and interactions. Featuring a reactive functional group, alkyne participates in many...

Fluorescent chemosensors containing redox-active ferrocene: a review

The redox-active ferrocene containing two cyclopentadienyl rings and iron was extensively employed in the field of sensing, catalysis, medicine, biotechnology etc., due to the structural stability, solubility in common solvents and easy structural modification to make a wide variety of ferrocene derivatives. The ferrocene moiety can be linked suitably with fluoro-chromogenic units and applied for the multichannel (fluorescent, chromogenic and redox) sensing of various bioactive and toxic analytes. This review was narrated to compile some important ferrocene based fluorescent chemosensors developed for the detection of metal ions, anions and neutral analytes. The analytical novelty and sensing mechanisms of the summarized chemosensors are discussed to open new scopes for future research.

Imine ligands based on ferrocene: synthesis, structural and Mössbauer characterization and evaluation as chromogenic and electrochemical sensors for Hg2+

Synthesis of imine ligands based on ferrocene and their evaluation as chromogenic and electrochemical sensors for Hg²⁺.

Luminescence of ferrocene-modified pyrene derivatives for turn-on sensing of Cu2+ and anions

Detection and identification of metal ions by fluorescent turn-on sensors are challenging due to the quenching effect of most of the tested metal ions. In the present work, three ferrocene-modified pyrene-based probes 2-4 were synthesized to act as turn-on fluorescent sensors for Cu²⁺. The measurements of fluorescence quantum yield and fluorescence lifetime reveal that ferrocenyl unit can efficiently reduce the fluorescence emission of pyrene moiety. Steady-state fluorescence measurements find that the three ferrocene-modified fluorophores exhibit selective turn-on responses to Cu²⁺. Moreover, this turn-on effect to Cu²⁺ is highly influenced by the type of the counter ion. It is found that the presence of Cl^- or NO₃^- could realize the turn-on response to Cu²⁺, whereas, the presence of SO₄^2- or Ac^- could not induce any fluorescence enhancement to Cu²⁺. Control experiments with ferrocene-free pyrene-based probe 1 reveal that the ferrocenyl unit plays the key role in the turn-on response to Cu²⁺. The possible mechanism for the turn-on responses is attributed to the oxidation behavior of Cu²⁺ to the ferrocene unit, which is confirmed by the control experiments with sodium ascorbate. Cyclic voltammetry measurements show that Cu²⁺ can influence the redox behaviors of ferrocenyl derivatives, which is also highly dependent on the anion of the copper salts. The influence of anion on the turn-on responses to Cu²⁺ was further used for anion detection and fluorescent logic gate.

Fluorescent and colorimetric detection of Fe(III) and Cu(II) by a difunctional rhodamine-based probe

A new rhodamine B hydrazone derivative (probe L) was synthesized and characterized. The probe L had sufficiently satisfactory selective response to Fe³⁺ and Cu²⁺ ions among various interferential metal ions, and high sensitivity with the detection limit of 4.63×10^-9M and 5.264×10^-7M for Fe³⁺ and Cu²⁺ ions, respectively. In the presence of Fe³⁺, the probe L exhibited turn-on orange fluorescence accompanied by color change from colorless to pink. Toward Cu²⁺, the probe L showed significant color change from colorless to red purple. These remarkable orange fluorescence and color change made probe L suitable naked-eye identify for Fe³⁺ and Cu²⁺ ions. By means of Job's plot, Benesi-Hildebrand studies and FTIR spectra, both 1:1 binding modes (L-Fe³⁺ and L-Cu²⁺) were confirmed. The coordination mechanism and turn on/off fluorescence for L-Fe³⁺ and L-Cu²⁺ complexes were well explained by theoretical calculations. Moreover, probe L could be used as a quick, simple, visual test strip for Fe³⁺ and Cu²⁺ detection.

Synthesis and structural characterization of electrochemically reversible bisferrocenes containing bis(acyl-thiourea)s: enantiomers and conformers

Enantiomeric and conformational isomers of chiral bisferrocenyl-modified bis(acyl-thiourea)s; their crystal packing and electrochemically reversible redox reaction properties.

Regioselective synthesis of spiroxindolopyrrolidine: a one step cycloaddition reaction twists inherent optical and fluorescence property of ferrocene–anthracene dyad

We report the regioselective synthesis of spiroxindole using a 1,3-dipolar cycloaddition reaction (1,3-DC). Our experiments show that cycloaddition can alter the inherent optical and fluorescence properties of the ferrocene–anthraced dyad system.