The syntheses, photophysical properties and pH-sensitive studies of heterocyclic azo dyes bearing coumarin-thiophene-thiazole.

This study reports the synthesis of two novel thiazolylazo dyes (4 and 5) bearing coumarin-thiophene moiety. UV-Vis spectroscopy was used to investigate the photophysical properties of 4 and 5 in different solvents. The dyes displayed good potential for hydroxide sensing in different mediums. The reversibility was also studied, and it was found that 4 and 5 could be reverted to their original state by adding acid. Furthermore, the acidochromic properties were studied in protic and aprotic media. Both dyes displayed a good acidochromic response in DCM. Moreover, 4 and 5 were investigated for pH sensing, and it was found that both compounds displayed changes in absorption spectra in a basic media. The theoretical calculations were carried out to investigate the deprotonation and protonation mechanisms using density functional theory (DFT). The thermal properties of the dyes were investigated using thermogravimetric analysis (TGA). The results showed good thermal stability up to around 200 °C.

Nucleophilic Approach to Cyanide Sensing by Chemosensors.

Cyanide anion has wide use in industrial areas; however, it has a high toxic effect on the environment as waste. Moreover, plant seeds contain cyanide that is often consumed by human beings. Therefore, many studies are carried out to determine cyanide. Especially, optical sensors showing colorimetric and fluorimetric changes have been of considerable interest due to their easy, cheap, and fast responses. This review discusses recent developments in the colorimetric and fluorimetric detection of cyanide by nucleophilic addition to different types of receptors via the chemodosimeter approach. The sensitivity and selectivity of the sensors have been reviewed for changes in absorption and fluorescence, naked-eye detection, real sample application, and detection limits when interacting with cyanide.

Recent advances in colorimetric and fluorometric sensing of neurotransmitters by organic scaffolds.

Neurotransmitters are chemical compounds released by neurons acting as messengers that transmit signals to other neurons, called postsynaptic neurons, or other types of cells. These neurotransmitters play a crucial role in the nervous system, and abnormalities in their levels have been associated with physical, psychotic, and neurodegenerative diseases such as Alzheimer's, Parkinson's, dementia, addiction, depression, and schizophrenia. This makes it necessary to develop sensitive and reliable techniques for their detection and monitoring in order to screen diseases. Meanwhile, neurotransmitters' detection remains a challenge and continues to attract considerable attention. Fluorescent and colorimetric organic probes were and still efficient tools for rapid, selective and low-cost detection of a large scale of analytes. Neurotransmitters can interact with the sensing molecule leading to the formation of complexes or new molecules displaying photophysical properties different from the starting fluorophore or/and chromophore and thus through different sensing mechanisms. Diverse applications of the sensors like live cell imaging are being reported. This review is a collection of recent development in the design of new organic receptors utilized for the detection of neurotransmitters including monoamines (catecholamines, serotonin and histamine), amino acids (glutamate, aspartate and glycine), gasotransmitters, and acetylcholine.

New platinum (II) and palladium (II) complexes of coumarin-thiazole Schiff base with a fluorescent chemosensor properties: Synthesis, spectroscopic characterization, X-ray structure determination, in vitro anticancer activity on various human carcinoma cell lines and computational studies.

A new coumarin-thiazole based Schiff base (Ligand, L) and its Pd(II), Pt(II) complexes; ([Pd(L)2] and [Pt(L)2]), were synthesized and characterized using spectrophotometric techniques (NMR, IR, UV-vis, LC-MS), magnetic moment, and conductivity measurements. A single crystal X-ray analysis for only L was done. The crystals of L have monoclinic crystal system and P21/c space group. To gain insight into the structure of L and its complexes, we used density functional theory (DFT) method to optimize the molecules. The photophysical properties changes were observed after deprotonation of L with CN- via intermolecular charge transfer (ICT). Additionally, as the sensor is a colorimetric and fluorimetric cyanide probe containing active sites such as coumarin-thiazole and imine (CH=N), it showed fast color change from yellow to deep red in the visible region, and yellow fluorescence after CN- addition to the imine bond, in DMSO. The reaction mechanisms of L with CN-, F- and AcO- ions were evaluated using 1H NMR shifts. The results showed that, the reaction of L with CN- ion was due to the deprotonation and addition mechanisms at the same time. The anti-cancer activity of L and its Pd(II) and Pt(II) complexes were evaluated in vitro using MTT assay on the human cancer lines MCF-7 (human breast adenocarcinoma), LS174T (human colon carcinoma), and LNCAP (human prostate adenocarcinoma). The anti-cancer effects of L and its complexes, on human cells, were determined by comparing the half maximal inhibitory concentration (IC50) values. The activity results showed that, the Pd(II) complex of L has higher anti-tumor effect than L and its Pt(II) complex against the tested human breast adenocarcinoma (MCF-7), human prostate adenocarcinoma (LNCAP), and human colon carcinoma (LS174T) cell lines.