A 3-hydroxyflavone derivative as fluorescence chemosensor for copper and zinc ions

A Review on Organic Colorimetric and Fluorescent Chemosensors for the Detection of Zn(II) Ions

Organic compounds display several electronic and structural features which enable their application in various fields, ranging from biological to non-biological. These compounds contain heteroatoms like sulfur, nitrogen and, oxygen, which provide coordination sites to act as ligands in the field of coordination chemistry and are used as chemosensors to detect various metal ions. This review article covers different organic compounds including Schiff bases, thiourea, pyridine, rhodamine, triazole, pyrene, coumarin, imidazole, diaminomaleonitrile, naphthoxazole, pyrimidine, thiophene, thioether, and other functional groups based chemosensors that contain heteroatoms like sulfur, nitrogen and, oxygen for fluorimetric and colorimetric detection of Zn(II) ions in different environmental, agricultural, and biological samples. Further, the sensing performances of these chemosensors have been compared and discussed which could help the readers for the future design of organic fluorescent and colorimetric chemosensors for the detection of Zn(II) ions. We hope this study will support the new thoughts to design a simple, efficient, selective, and sensitive chemosensor for the detection of Zn(II) ions in different samples (environmental, agricultural, and biological).

Complexation of 1,3-dihetaryl-5-phenyl-2-pyrazoline Derivatives with Polyvalent Metal Ions: Quantum Chemical Modeling and Experimental Investigation

1,3,5-Triaryl-2-pyrazoline derivatives with a pyridine ring in position 1 and 2-benzimidazolyl or 2-benzothiazolyl bicycles in position 3 were synthesized. Spectral properties in solvents of similar polarity, i.e. aprotic acetonitrile and in protic methanol, were studied, complexation with cadmium and mercury ions in acetonitrile was elucidated as well. Quantum-chemical modeling with application of the elements of Bader's atoms-in-molecules (AIM) theory of the title molecules conformational structure and 1:1 stoichiometry complexes formed with polyvalent metals of various nature (Mg, Zn, Cd, Pb, Hg, Ba) was conducted. The principal possibility of “nitrogen-sulfur” switching of the metal ions binding sites for the benzothiazole derivative was revealed, and makes possible to classify this compound as “smart ligand”.

3-Hydroxyflavone derivatives: promising scaffolds for fluorescent imaging in cells

As a typical class of excited-state intramolecular proton transfer (ESIPT) molecules, 3-hydroxyflavone derivatives (3HF, also known as flavonols) have received much attention recently. Thereinto, the role of hydrophobic microenvironment is significant importance in promoting the process and effects of ESIPT, which can be regulated by the solvents, the existence of metal ions and proteins rich with α-helix structures or the advanced DNA structures. Considering that plenty of biological macromolecules offer cellular hydrophobic microenvironment, enhancing the ESIPT effects and resulting in dual emission, 3HF could be a promising scaffold for the development of fluorescent imaging in cells. Furthermore, as the widespread occurance of compounds with biological activity in plants, 3HF derivatives are much more secure to be cellular diagnosis and treatment integrated fluorescent probes. In this review, multiple regulatory strategies for the fluorescence emission of 3HF derivatives have been collectively and comprehensively analyzed, including the solvent effects, metal chelation, interaction with proteins or DNAs, which would be beneficial for ESIPT-promoting or ESIPT-blocking processes and then enhance or control the fluorescence emission of 3HF effectively. We expect that this review would provide a new perspective to develop novel 3HF-based fluorescent sensors for imaging in cells and plants.