A novel quinoline-based turn-on fluorescent probe for the highly selective detection of Al (III) and its bioimaging in living cells, plants tissues and zebrafish

Luminous Insights: Exploring Organic Fluorescent "Turn-On" Chemosensors for Metal-Ion (Cu+2, Al+3, Zn+2, Fe+3) Detection

There are several metal ions that are vital for the growth of the environmental field as well as for the biological field but only up to the maximum limit. If they are present in excess, it could be hazardous for the human health. With the growing technology, a series of various detection techniques are employed in order to recognize those metal ions, some of them include voltammetry, electrochemical methods, inductively couples, etc. However, these techniques are expensive, time consuming, requires large storage, advanced instrumentation, and a skilled person to operate. So, here comes the need of a sensor and it is defined as a miniature device which detects the substance of interest by giving response in the form of energy change. So, from past few decades, many sensors have been formulated for detecting metal ions with some basic characteristics like selectivity, specificity, sensitivity, high accuracy, lower detection limit, and response time. Detecting various metal ions by employing chemosensors involves different techniques such as fluorescence, phosphorescence, chemiluminescence, electrochemical, and colorimetry. The fluorescence technique has certain advantages over the other techniques. This review mainly focuses on the chemosensors that show a signal in the form of fluorescence to detect Al+3, Zn+2, Cu+2, and Fe+3 ions.

A highly sensitively "off-on-off" fluorescence probe for detection of aluminum ion and water as well as application in Chinese Baijiu

Developing highly sensitive fluorescent probe for Al3+ and H2O detection is highly desirable, due to aluminum toxicity poses a significant threat to public health. On the other hand, the determination of water content holds immense significance in a wide range of fields such as food processing, pharmaceutical manufacturing. In this paper, a novel acylhydrazone-based fluorescent probe P was successfully synthesized and characterized for the sequential detection of Al3+ and water in alcohols. The probe P exhibited a remarkable "turn-on" response towards Al3+ by emitting yellow fluorescence at 567 nm, with high selectivity and large Stokes shift (147 nm). Meanwhile, the in situ formed P-Al3+ complex demonstrated significant solvatofluorochromic characteristic, which could be utilized as a second probe for detecting water via fluorescence quenching with low detection limit in alcohols (0.008%, methanol; 0.013%, ethanol; 0.013%, isopropanol; 0.037%, n-butanol; vol.%) and acetonitrile (0.072%, vol.%). Moreover, the P-Al3+ complex was able to detect the alcoholic strength of Chinese Baijiu without the interference of other alcohols, providing an excellent recovery rate (100.0-107.0%). Different Chinese Baijius, with various alcoholic strength, could be distinguished by simple test strips. Furthermore, the P-Al3+ complex could also analyze the water content in organic solvents .

Influence of derivatives of 2-((6-r-quinolin-4-yl)thio)acetic acid on rhizogenesis of Paulownia clones

In recent years, the demand for effective and low-toxic stimulators of rhizogenesis, which are used in microclonal propagation of plants, has been increasing in Ukraine. One of the promising directions in the search for effective compounds is molecular modeling based on known natural and synthetic compounds. The development of new highly effective and low-toxic biologically active compounds is largely based on derivatives of nitrogen-containing heterocycles, and quinoline occupies a significant place among them. Modern methods of chemometric analysis make it possible to find certain regularities in the "chemical structure – biological activity" and to select the most promising compounds for experimental research. The values of lipophilicity log P for neutral forms and the value of the distribution coefficient log D at pH = 7 were obtained by quantum chemical calculation. The values of log P and log D of the studied compounds are in the most favourable interval for overcoming the biological membranes of the cells of the root system, depending on the pH of the environment. According to Lipinski’s "rule of five", all studied compounds can show high biological activity. The toxicity of compounds of 2-((6-R-quinolin-4-yl)thio)acetic acid derivatives was evaluated by computer programs and experimentally. Among the derivatives of 2-((6-R-quinolin-4-yl)thio)acetic acid, the most toxic compounds were those that did not have alkoxy substituents in the 6th position of the quinoline ring. Sodium salts are more toxic than the corresponding acids. This is due to an increase in the bioavailability of ionized compounds. Derivatives of 2-((6-R-quinolin-4-yl)thio)acetic acid (sodium salt of 2-((quinolin-4-yl)thio)acetic acid (QAC-5) showed the greatest toxic effect on the model of the study of progressive sperm motility) and 2-((quinolin-4-yl)thio)acetic acid (QAC-1), which will reduce this indicator by 15–20% compared to intact. The toxicity assessment of the studied compounds made it possible to determine a number of factors of the structure of molecules which affect the level of toxic action of 2-((6-R-quinolin-4-yl)thio)acetic acid derivatives and the directions of creation of non-toxic growth stimulants in this series. The impact on rhizogenesis during microclonal reproduction in vitro in explants Paulownia clone 112 and further adaptation of microplants in vivo hybrid molecules of quinoline and acetic acid, which are analogues of known growth stimulants, was studied. A number of factors influencing the level of influence on rhizogenesis of the action of derivatives of 2-((6-R-quinolin-4- yl)thio)acetic acid and directions of creation of highly active substances in this series was defined. The studied compounds showed a high stimulating effect on rhizogenesis in vitro in Paulownia explants. It was established that the sodium salt of 2-((quinolin-4-yl)thio)acetic acid was the greatest stimulator of rhizogenesis compared to the corresponding original acid. The presence of alkoxy groups in the 6th position and methyl in the 2nd position of the quinoline ring of 2-((6-R-quinolin-4-yl)thio)acetic acid reduced the activity of the compounds. The selection of new effective, low-toxic, less expensive substances was carried out for further testing as potential stimulators of rhizogenesis for microclonal propagation of plants.

A simple hydrazone probe for recognition of Al3+ and PPi and its applicability in lysosomal imaging

A simple hydrazone probe (1) was designed and synthesized for the successive detection of Al³⁺ and pyrophosphate (PPi) in almost 100% buffer environment. The probe provided O₂N donor set for chelation with Al³⁺, leading to a distinct fluorescence boost at 510 nm. The in-situ formed 1-Al³⁺ complex detected PPi with an "on-off" behavior. The detection limits for Al³⁺ and PPi were 35.7 nM and 76 nM, respectively. Benefiting from the existence of morpholine as lysosome-targeting group, probe 1 was successfully applied to the detection of Al³⁺ and PPi in lysosomes.

Advances in the site-selective C-5, C-3 and C-2 functionalization of chromones via sp2 C-H activation

In this work, site-selective C-H activation at C-5, C-3 and C-2 positions of chromones for the introduction of structural diversity to the chromone scaffold was studied. The keto group of the chromone moiety acts as the directing group for the selective functionalization of chromones at the C-5 position. Furthermore, the C-H functionalization at the electron-rich C-3 position of the chromone can be achieved using electrophilic coupling partners. The C-H functionalization at the C-2 position can be possible using nucleophilic coupling partners. The direct functionalization methods provide a better pathway for the generation of C-5, C-3 and C-2-substituted chromones with good atom economy than that of classical pre-functionalized reaction protocols.

The crystal structure of 6,6′-((1E,1′E)-hydrazine-1,2-diylidenebis(methaneylylidene)) bis(2-bromo-4-nitrophenol) — dimethylsulfoxide (1/2), C14H8Br2N4O6⋅2(C2H6OS)

C14H8Br2N4O6⋅2(C2H6OS), triclinic, P 1 ‾ $P\bar{1}$ (no. 2), a = 6.1463(12) Å, b = 8.3637(16) Å, c = 12.461(3) Å, α = 85.578(5)°, β = 85.942(5)°, γ = 86.310(5)°, V = 635.9(2) Å3, Z = 1, R gt (F) = 0.0601, wR ref (F 2) = 0.0983, T = 296 K.

CCDC no.: 2057510