Anthraquinone appended chemosensors for fluorescence monitoring of anions and/or metal ions

Carbohydrazone/Thiocarbohydrazone-Based Dual-Responsive Probes for Highly Selective Detection of Cu2+/Fe3+ Cations and F-/ClO4 - Anions, and Their Application in Bioimaging of Live Cells and Zebrafish Larvae

Four dual-responsive probe molecules 1,5-bis(thiophene-2-carbaldehyde)carbohydrazone (R1), 1,5-bis(thiophene-2-carbaldehyde)thiocarbohydrazone (R2), 1,5-bis(indole-3-carbaldehyde)carbohydrazone (R3), and 1,5-bis(indole-3-carbaldehyde)thiocarbohydrazone (R4) were synthesized, characterized, and investigated for their sensing efficacy. The initial sensing behavior of the probes was tested by colorimetric signaling, followed by spectral and theoretical techniques, which supported the dual-sensing ability of the selected inorganic ions. The probes exhibited highly selective optical recognition for Cu2+/Fe3+ cations and F-/ClO4 - anions compared to the tested cations and anions. Interestingly, the addition of Cu2+ and F- ions to the probes resulted in "turn-on" fluorescence responses. Job's plot studies showed 1:2 stoichiometry between the probe molecules and cations and 1:1 stoichiometry between the probe molecules and anions. The binding constant of the probe molecules with the sensed ions was determined by the Benesi-Hildebrand equation and was found to be between 7.08 × 104 and 7.44 × 106 M-1 with a limit of detection between 0.11 and 0.80 μM, in CH3CN:DMF (9:1, v/v). Density functional theory calculations established the nature of the interaction between the probe molecules and sensed ions. Further, the practical utility of the probes was successfully demonstrated with paper strip experiments, fluorescence imaging of Cu2+ ions in DrG cells and zebrafish larvae, as well as in the development of molecular logic gates.

Selective detection of Fe3+ via fluorescent in real sample using aminoanthraquinone resorcin[4]arene-based receptors with logic gate application

Resorcin[4]arene based fluorescent sensors RES-AAQ containing eight anthraquinone groups as binding sites, were developed for very accurate and sensitive detection of Fe3+ metal ion. The motivation for this study lies in the need for advanced sensing techniques for precisely identifying Fe3+ ions. Due to its unique redox properties, Fe3+ plays a crucial role in biological processes, environmental remediation, medical diagnostics, and advanced detection methods. The sensors were extensively characterized using FT-IR, 1H NMR, 13C NMR, and ESI-MS techniques. The absorption spectra revealed significant interactions between RES-AAQ and Fe3+ ions. Fluorescence quenching was observed due to Photoinduced electron transfer (PET). The quenching process was systematically analyzed using Stern-Volmer analysis. Each sensor (L1, L2, L3, L4) demonstrated remarkable detection limits for Fe3+ ions (10.51 nM, 10.48 nM, 10.49 nM, 10.47 nM, respectively) along with substantial binding affinities (binding constants: 9.07x109 M-1, 1.19x109 M-1, 1.49x109 M-1 and 1.03x109 M-1 for L1, L2, L3, and L4, respectively). Traditional, Fe3+ detection methods often suffer from limitations such as complexity, lack of sensitivity, or interference from other metal ions. This research offers highly sensitive fluorescent sensors for Fe3+ detection with potential applications in human blood serum and tap water. Molecular docking, DFT studies, and ESI-MS investigation have been employed to gain insights into the binding interactions between the molecules. The low detection limits, high binding affinity, and real-world applicability highlight the significant advantages of developed sensors compared to existing methods. Additionally, a combinatorial logic gate was constructed to facilitate a proper understanding of the working principle of RES-AAQ.

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.

Exploring the interaction of biologically active compounds with DNA through the application of the SwitchSense technique, UV-Vis spectroscopy, and computational methods

DNA is a key target for anticancer and antimicrobial drugs. Assessing the bioactivity of compounds involves in silico and instrumental studies to determine their affinity for biomolecules like DNA. This study explores the potential of the switchSense technique in rapidly evaluating compound bioactivity towards DNA. By combining switchSense with computational methods and UV-Vis spectrophotometry, various bioactive compounds' interactions with DNA were analyzed. The objects of the study were: netropsin (as a model compound that binds in the helical groove), as well as derivatives of pyrazine (PTCA), sulfonamide (NbutylS), and anthraquinone (AQ-NetOH). Though no direct correlation was found between switchSense kinetics and binding modes, this research suggests the technique's broader utility in assessing new compounds' interactions with DNA. used as analytes whose interactions with DNA have not been yet fully described in the literature.

Effect of Substituents on Solubility, Medicinal, Absorption, Emission and Cationic/Anionic Detection Properties of Anthraquinone Derivatives

Anthraquinones constitute an important class of compounds with wide applications. The solubility of derivatives at 298.15 K was discussed in ethanol-water solution and at atmospheric pressure, the solubility of 1-amino-4-hydroxy-9,10-anthraquinone (AHAQ) in binary solvents (ethanol-water combinations) was determined. Colour strength and fastening properties depend upon the kind and position of a hydrophobic group connected to the phenoxy ring of Anthraquinone moiety. There is a continuing interest in the creation of novel anthraquinone derivatives with biological activities since they have demonstrated potential for treating multiple sclerosis. For this purpose, by utilizing voltammetric and absorption studies, interactions of various derivatives with calf thymus DNA (ct-DNA) and the cationic surfactant cetyltrimethylammoniumbromide (CTAB) were examined. Here prominent Hydrophobic interaction and electron transfer resulting in binding to CTAB micelles were observed. The polarity index of the media was assessed and associated with the electrochemical parameters. The medicinal behaviour of Anthraquinone derivatives was a result of electron transfer reactions with DNA. UV-Visible and fluorescence properties were due to the transitions between n* and π* orbitals. Large absorption band with low dichroic ratio was characteristic of various derivatives of Anthraquinone. Presence of -NH group proves various derivatives remarkable calorimetric and anionic sensors.

Tuning sensing efficacy of anthraimidazoledione-based charge transfer dyes: nitro group positioning impact

Anthraimidazoledione-based optical sensors have been designed by varying the position of the nitro functional group. All three positional isomers showed highly colored, photostable optical signals owing to intramolecular charge transfer interactions. Despite having the same anion-binding site (imidazole unit), the selectivity and sensitivity of the compounds depend on the positioning of the nitro group. The selectivity was fairly good for the meta isomer, followed by the ortho and para isomers, respectively. In contrast, the sensitivity towards anions followed a completely opposite trend, with the para isomer being the most sensitive one towards anions. Interestingly, the color changing response along the turn-on fluorescence signal was observed only with CN- ions in a semi-aqueous environment. Though the introduction of water as a co-solvent could improve the selectivity, the sensitivity was found to be slightly less than that observed in pure organic medium. Mechanistic studies indicated hydrogen bonding interactions between the imidazole -NH proton and cyanide, which further facilitated the extent of intramolecular charge transfer.

A Comparative Study of New Fluorescent Anthraquinone and Benzanthrone α-Aminophosphonates: Synthesis, Spectroscopy, Toxicology, X-ray Crystallography, and Microscopy of Opisthorchis felineus

In this research, we explore the synthesis of and characterize α-aminophosphonates derived from anthraquinone and benzanthrone, focusing on their fluorescence properties and potential applications in confocal laser scanning microscopy (CLSM). The synthesized compounds exhibit notable solvatochromic behavior, emitting fluorescence from green to red across various solvents. Spectroscopic analysis, including 1H-, 13C-, and 31P-NMR, FTIR, and mass spectrometry, confirms the chemical structures. The compounds' toxicity is evaluated using etiolated wheat sprouts, revealing varying degrees of impact on growth and oxidative damage. Furthermore, the study introduces these α-aminophosphonates for CLSM imaging of the parasitic flatworm Opisthorchis felineus, demonstrating their potential in visualizing biological specimens. Additionally, an X-ray crystallographic study of an anthraquinone α-aminophosphonate provides valuable structural insights.

KuQuinones: a ten years tale of the new pentacyclic quinoid compound

Quinones are widespread in nature, as they participate, mainly as redox mediators, in several biochemical processes. Up to now, various synthetic quinones have been recommended in the literature as leading molecules in energy, biomedical and catalytic fields. In this brief review, we retraced our research activity in the last ten years, mainly dedicated to the study of a new class of peculiar pentacyclic conjugated quinoid compounds, synthesized in our group. In particular, their application as sensitive materials in photoelectrochemical devices and in biosensors, as photocatalysts in selective oxidation reactions, and their anticancer activity is here reviewed.

Selective Recognition and Reversible “Turn-Off” Fluorescence Sensing of Acetate (CH3COO−) Anion at Ppb Level Using a Simple Quinizarin Fluorescent Dye

A simple and cost-effective optical sensing system based on quinizarin fluorescent dye (QZ) for the selective and reversible sensing of CH3COO− anions is reported. The anion binding affinity of QZ towards different anions was monitored using electronic absorption and fluorescence emission titration studies in DMSO. The UV-visible absorption spectrum of QZ showed a decrease in the intensity of the characteristic absorption peaks at λ = 280, 323, and 475 nm, while a new peak appeared at λ = 586 nm after the addition of CH3COO− anions. Similarly, the initial strong emission intensity of QZ was attenuated following titration with CH3COO− anions. Notably, similar titration using other anions, such as F−, Cl−, I−, NO3−, NO2−, and H2PO4-, caused no observable changes in both absorption and emission spectra. The selective sensing of CH3COO− anions was also reflected by a sharp visual color change from bright green to faint green under room light. Further, the binding was found to be reversible, and this makes QZ a potential optical and colorimetric sensor for selective, reversible, and ppb-level detection of CH3COO− anions in a DMSO medium.