Ratiometric Detection of Mercury (II) Ions in Living Cells Using Fluorescent Probe Based on Bis(styryl) Dye and Azadithia-15-Crown-5 Ether Receptor

Effects of Metal Ions and Substituents on HOMO-LUMO Gap Evident from UV-Visible and Fluorescence Spectra of Anthracene Derivatives

Controlled intake of complex metal cations and anions in the human body and other biological systems is essential for the health and well-being of the environment. Anthracene and anthracene derivatives are the most widely used sensors for this purpose. Because of their convenience, better detection and results are preferred over colorimetric sensors, which offer better color detection by the naked eye. This review article will present different designs of chemosensors using fluorescence and UV-visible spectroscopy to determine different ions. Density functional theory and Austin model 1 are widely used for theoretical and computational studies of the energy levels of molecules. The Indo/Cis method is used to calculate the geometries of anthracene oligomers. A novel anthracene-based fluorescent probe containing the benzothiazole group BFA was highly sensitive and selective toward trivalent cations (Cr3+ and Fe3+). This sensor is not sensitive to other ions, including Aluminum trivalent ions. (N- ((anthracen-9-yl) methyl)-N-(pyridin-2-yl) pyridin-2-amine) has been designed to detect zinc and copper. Click chemistry using photodimerization can be used to form cellulose nanoparticles. TEMPO-mediated hypohalite oxidation converts hydroxyl groups to carboxylic groups. Amide linkage formation between amine and carboxylic acid was followed by the installation of an alkyne group. Copper (I)-catalyzed Azide-Alkyne Cycloaddition (CuAAC) was used to produce highly photoresponsive and fluorescent cellulose nanoparticles by using coumarin, anthracene, and generated nanomaterials. The effects of naphthalene and phenanthrene on the spectra of anthracene were determined in a dilute solution. Temperature and solvent effects introduce different changes in fluorescence, emission, and absorption bands, leading to some changes in the configuration of anthracene. The solvent and temperature effects on variations of emission maxima of exciplex anthracene-diethylaniline (DEA) are also discussed.

Styrylpyridinium Derivatives for Fluorescent Cell Imaging

A set of styrylpyridinium (SP) compounds was synthesised in order to study their spectroscopic and cell labelling properties. The compounds comprised different electron donating parts (julolidine, p-dimethylaminophenyl, p-methoxyphenyl, 3,4,5-trimethoxyphenyl), conjugated linkers (vinyl, divinyl), and an electron-withdrawing N-alkylpyridinium part. Geminal or bis-compounds incorporating two styrylpyridinium (bis-SP) moieties at the 1,3-trimethylene unit were synthesised. Compounds comprising a divinyl linker and powerful electron-donating julolidine donor parts possessed intensive fluorescence in the near-infrared region (maximum at ~760 nm). The compounds had rather high cytotoxicity towards the cancerous cell lines HT-1080 and MH-22A; at the same time, basal cytotoxicity towards the NIH3T3 fibroblast cell line ranged from toxic to harmful. SP compound 6e had IC50 values of 1.0 ± 0.03 µg/mL to the cell line HT-1080 and 0.4 µg/mL to MH-22A; however, the basal toxicity LD50 was 477 mg/kg (harmful). The compounds showed large Stokes' shifts, including 195 nm for 6a,b, 240 nm for 6e, and 325 and 352 nm for 6d and 6c, respectively. The highest photoluminescence quantum yield (PLQY) values were observed for 6a,b, which were 15.1 and 12.2%, respectively. The PLQY values for the SP derivatives 6d,e (those with a julolidinyl moiety) were 0.5 and 0.7%, respectively. Cell staining with compound 6e revealed a strong fluorescent signal localised in the cell cytoplasm, whereas the cell nuclei were not stained. SP compound 6e possessed self-assembling properties and formed liposomes with an average diameter of 118 nm. The obtained novel data on near-infrared fluorescent probes could be useful for the development of biocompatible dyes for biomedical applications.

The spectroscopic and computational study of anthracene based chemosensor - Ag+ interactions

Here in, we demonstrate a selective detection of Ag⁺ ion by the anthracene-based schiff base sensor AMC. The recognition event among sensor AMC and Ag⁺ ion was investigated by enhanced absorption band, red-shifted quenched emission spectra, electrochemical studies and DFT computational studies. The presence of Ag⁺ ion to solution of AMC quenched almost 50 % emission intensity of the ligand band. Data from high-resolution electrospray ionization mass spectrometry (ESI-HRMS), Ag⁺ titrations, and Job's plot studies all show that Ag⁺ binds to AMC in a 1:1 stoichiometric ratio.The quantitative parameters of sensor for silver ion are determined as the limit of detection (LOD) 5.95 × 10^-7 M, and limit of quantitation (LOQ) 1.98 × 10^-8 M in the linear range 3.48-20.31 × 10^-6 M with good association affinity of 5.030 × 10³ M^-1. LMCT phenomenon from insilico studies, is in good agreement with the results obtained from other performed spectroscopic techniques. In addition, this sensor AMC was also successfully applied to real water samples for the identification and measurement of Ag⁺ ions.

Fluorescent RET-Based Chemosensor Bearing 1,8-Naphthalimide and Styrylpyridine Chromophores for Ratiometric Detection of Hg2+ and Its Bio-Application

Dyad compound NI-SP bearing 1,8-naphthalimide (NI) and styrylpyridine (SP) photoactive units, in which the N-phenylazadithia-15-crown-5 ether receptor is linked with the energy donor naphthalimide chromophore, has been evaluated as a ratiometric fluorescent chemosensor for mercury (II) ions in living cells. In an aqueous solution, NI-SP selectively responds to the presence of Hg²⁺ via the enhancement in the emission intensity of NI due to the inhibition of the photoinduced electron transfer from the receptor to the NI fragment. At the same time, the long wavelength fluorescence band of SP, arising as a result of resonance energy transfer from the excited NI unit, appears to be virtually unchanged upon Hg²⁺ binding. This allows self-calibration of the optical response. The observed spectral behavior is consistent with the formation of the (NI-SP)·Hg²⁺ complex (dissociation constant 0.13 ± 0.04 µM). Bio-imaging studies showed that the ratio of fluorescence intensity in the 440–510 nm spectral region to that in the 590–650 nm region increases from 1.1 to 2.8 when cells are exposed to an increasing concentration of mercury (II) ions, thus enabling the detection of intracellular Hg²⁺ ions and their quantitative analysis in the 0.04–1.65 μM concentration range.