A new thiophenyl pyrazoline fluorescent probe for Cu2+ in aqueous solution and imaging in live cell

A Review on Pyrazolines as Colorimetric Fluorescent Chemosensors for Cu2

The Pyrazoline derivatives display promising potential as sensitive and selective chemosensors for detecting Cu2+ ions. It has undergone screening for its sensing behavior with various metals using absorption, emission spectroscopic techniques. Their unique structure incorporates both donating and accepting sites, characterized by delocalized orbitals. These derivatives exhibit notable chromogenic and fluorogenic capabilities facilitated by intramolecular charge transfer. The sensors based on pyrazoline demonstrate exceptional selectivity, low detection limits, and precise detection of metal ions, particularly Cu2+. This review offers a comprehensive summary of recent discoveries concerning as pyrazoline-based "On-Off" chemosensors. The discussion places emphasis on exploring the design and photophysical properties of these chemosensors, with the primary objective of detecting Cu2+ metal ions. The unique features of pyrazoline derivatives make them promising candidates for practical applications in environmental and biological monitoring, showcasing their potential significance in advancing sensing technologies.

Small-Molecule Fluorescent Probes for Binding- and Activity-Based Sensing of Redox-Active Biological Metals

Although transition metals constitute less than 0.1% of the total mass within a human body, they have a substantial impact on fundamental biological processes across all kingdoms of life. Indeed, these nutrients play crucial roles in the physiological functions of enzymes, with the redox properties of many of these metals being essential to their activity. At the same time, imbalances in transition metal pools can be detrimental to health. Modern analytical techniques are helping to illuminate the workings of metal homeostasis at a molecular and atomic level, their spatial localization in real time, and the implications of metal dysregulation in disease pathogenesis. Fluorescence microscopy has proven to be one of the most promising non-invasive methods for studying metal pools in biological samples. The accuracy and sensitivity of bioimaging experiments are predominantly determined by the fluorescent metal-responsive sensor, highlighting the importance of rational probe design for such measurements. This review covers activity- and binding-based fluorescent metal sensors that have been applied to cellular studies. We focus on the essential redox-active metals: iron, copper, manganese, cobalt, chromium, and nickel. We aim to encourage further targeted efforts in developing innovative approaches to understanding the biological chemistry of redox-active metals.

Microwave-assisted synthesis for a highly selective rhodamine 6G-derived fluorescent sensor and bioimaging

A new rhodamine 6G derivative R1 has been synthesized by condensation of rhodamine hydrazide and 6-hydroxymethyl-pyridine using microwave-assisted reaction. Naked-eye colorimetric and photo physical studies show the synthesized compound is selectively sensing Cu2+ in CH3CN/H2O (9:1, v/v) solution. Upon coordination with Cu2+ ion, the spirolactam of R1 is opened, which results in a formation of highly fluorescent complex and change in color of the solution. The Job's plot indicates 1:2 binding stoichiometry between Cu2+ ion and R1. Limit of detection for Cu2+ was determined to be 1.23 μM. The sensor was successfully applied to fluorescent imaging of Cu2+ ion in living cells.

A Review on Metal Ion Sensors Derived from Chalcone Precursor

Disclosure of new molecular probes as chromogenic and fluorogenic cation sensors is scientifically exigent work. Recently chalcone derivatives gained more attention because of their structural variability. A suitable donor and acceptor groups separated by delocalized π-orbitals display excellent chromogenic and fluorogenic properties because of intramolecular charge transfer (ICT). These designed molecular frameworks provide the coordination sites to the incoming metal ions results in small changes in the optical properties. In a typical sensing behavior, coordination leads to a large conjugation plane with the probe resulted in hypo/hyperchromic shifts or red/blue shifts. In this review, we tried to converge the reported chalcone-derived sensors and explored the design, synthesis, metal ion sensing mechanism, and practical application of the probes. We expect that this review gives a basic outline for researchers to explore the field of chalcone-based sensors further.

Discovery of new fluorescent thiazole-pyrazoline derivatives as autophagy inducers by inhibiting mTOR activity in A549 human lung cancer cells

A series of fluorescent thiazole–pyrazoline derivatives was synthesized and their structures were characterized by ¹H NMR, ¹³C NMR, and HRMS. Biological evaluation demonstrated that these compounds could effectively inhibit the growth of human non-small cell lung cancer (NSCLC) A549 cells in a dose- and time-dependent manner in vitro and inhibit tumor growth in vivo. The structure–activity relationship (SAR) of the compounds was analyzed. Further mechanism research revealed they could induce autophagy and cell cycle arrest while had no influence on cell necrosis. Compound 5e inhibited the activity of mTOR via FKBP12, which could be reversed by 3BDO, an mTOR activator and autophagy inhibitor. Compound 5e inhibited growth, promoted autophagy of A549 cells in vivo. Moreover, compound 5e showed good selectivity with no influence on normal vascular endothelial cell growth and the normal chick embryo chorioallantoic membrane (CAM) capillary formation. Therefore, our research provides potential lead compounds for the development of new anticancer drugs against human lung cancer.

Synthesis, Spectral Characterization and Fluorescent Assessment of 1,3,5-Triaryl-2-pyrazoline Derivatives: Experimental and Theoretical Studies

Two new pyrazoline derivatives, namely 5-(4-bromophenyl)-3-(5-chlorothiophen-2-yl)-1-phenyl-4,5-dihydro-1H-pyrazole (3) and 5-(4-bromophenyl)-3-(2,5-dichlorothiophen-3-yl)-1-phenyl-4,5-dihydro-1H-pyrazole (4) have been synthesized and characterized based on their spectral (IR, (1)H and (13)C NMR and MS) data and microanalysis. The fluorescence properties of 3 and 4 were studied by UV-Vis and emission spectroscopy. For compound 3, a fluorescence emission was observed in the blue region of the visible spectrum. The effect of different solvents on fluorescence was also investigated. Density Functional Theory calculations have also been performed to gain insight into geometric, electronic and spectroscopic properties of the pyrazoline derivatives. Both structures are analysed and compared in order to rationalize the different behaviour in 3 and 4.

Synthesis of novel boron chelate complexes and proposed mechanism of new rearrangement

We synthesized novel boron chelate complexes by the reaction of pyrazoline derivatives and boron trifluoride diethyl etherate followed by a new rearrangement. The structures of the compounds were characterized by IR, NMR and HRMS, especially, a typical compound 3c was confirmed by X-ray single crystal analysis. We proposed a mechanism of the rearrangement. Moreover, the absorption and fluorescence spectroscopy of these compounds were measured.

Novel pyrazoline-based selective fluorescent probe for the detection of hydrazine

A novel pyrazoline-based fluorescent probe, 2-[4-(3,5-diphenyl-4,5-dihydro-pyrazol-1-yl)-benzylidene]-malononitrile, with a simple structure and low detection limit (6.16×10(-6)M) for the detection of hydrazine is designed and synthesized. The probe responds selectively to hydrazine over other molecules with marked fluorescence enhancement. The probe can detect hydrazine effectively at pH 5.0-9.0 with a special emission wavelength at 520nm. Moreover, the probe can be used to detect hydrazine from variety of natural source water.

Design, synthesis and biological evaluation of a novel Cu2+-selective fluorescence sensor for bio-detection and chelation

A new coumarin-based Cu²⁺-selective fluorescent sensor was designed and synthesized and the ability of this fluorescent sensor for the detection and chelation of Cu²⁺ in cultured cells was investigated.