A fluorescent chemoprobe based on carbazole for hypochlorite with fast response: Design and its applications in test strips, water samples and living cells

Hypochlorite (ClO-) has been widely used as the main component of cleaning agents, and is also used in the treatment of disinfect water. The concentration of ClO- is critical for living organisms andthe environment. Hence, it is essential to develop reliable, sensitive and user-friendly molecular sensors to determine ClO-. In this context, the synthesized probe 2,4-di-tert-butyl-6-((E)-(((E)-(9-pentyl-9H-carbazol-3-yl)methylene) hydrazono) methyl) phenol (TBCP) can detect ClO- with rapid response (1 min), low detection limit (0.28 µM) and high sensitivity. Also, the sensor is utilized at wide pH range (4-10) for the determination of ClO-. TBCP showed outstanding selectivity for ClO- over other competing analytes via a fluorescent response change from colorless to orange, and its response mechanism was based on a deprotonation phenomenon. The ClO- level was successfully determined by TBCP on test kits, cotton swabs and in real samples. Fluorescent bio-imaging of ClO- in HEPG2 cells was also carried out in the presence of TBCP. Furthermore, DFT calculations were performed successfully for TBCP and TBCP + ClO- complex.

A ″On-Off″ Fluorescent Sensor Based on Coumarin-Furoic Hydrazide for Recognition of Fe3+: Drinking Water, Test Strip Applications and DFT Calculations

A coumarin based fluorescent probe (E)-N'-((7-hydroxy-2-oxo-2H-chromon-3-yl)methylene)furan-2-carbohydrazide (CFHZ) was synthesized for the detection of Fe3+ and its characterizations were carried out using spectroscopic methods such as FT-IR, mass spectrometry1H-NMR, 13C-NMR. The novel probe CFHZ showed a highly selective and sensitive "turn-off" response to Fe3+ ion without any interference from other analytes. Strong fuorescence quenching phenomena of the CFHZ were observed in EtOH:H2O (99/1, v/v) detection system (λem = 470 nm) upon the additions of Fe3+. The binding stoichiometry between CFHZ and Fe3+ was determined by Job's method, FT-IR and MALDI TOF-MS and found to be 2:1. Also, the binding constant was determined to be 1.82 × 105 M-1 and the limits of detection for the analysis of Fe3+ was measured as 25.7 nM. Besides, experimental applications were carried out for real-time monitoring of Fe3+ in water samples using developed sensor. Additionally, fluorescence imaging experiments for Fe3+ detection of CFHZ probe on test papers were successfully performed.

A New Fluorene-Based Fluorescent Probe for Recognition of Hypochlorite Ions and its Applications

Oxidative stress is a trigger for many diseases and occurs with the unstable hypochlorite (ClO-), known as one of the reactive oxygen species (ROS) in organisms. Then, HOCI is acknowledged as an oxidizing species that eliminates a variety of environmental pollutants. Hence, the development of novel methodologies for the selective and precise identification of HOCl/ ClO- is considered to be of utmost importance. In this study, the design, characterization, and applications of a fluorene-based fluorescent probe (FHBP) dependent on the ESIPT mechanism with a "turn-on" response for the sensitive/selective determination of ClO- against other competing samples were reported. The experimental results indicated that the detection limit for ClO-could be quantitatively determined by the probe to be 8.2 × 10-7 M. The binding constant of the probe FHBP with ClO- was computed as 9.75 × 103 M-1. In addition, the response time of FHBP was appointed to be 30 s, indicating a rapid reaction with ClO-. It has also been demonstrated that this probe can be successfully used for the detection of ClO- on filter papers, TLC sheets, cotton swabs, and real samples.

Synthesis, characterization, antimicrobial activity and carbonic anhydrase enzyme inhibitor effects of salicilaldehyde-N-methyl p-toluenesulfonylhydrazone and its Palladium(II), Cobalt(II) complexes

We report the synthesis of the ligand, salicilaldehyde-N-methyl p-toluenesulfonylhydrazone (salptsmh) derived from p-toluenesulfonicacid-1-methylhydrazide (ptsmh) and its Pd(II) and Co(II) metal complexes were synthesized for the first time. The structure of the ligand and their complexes were investigated using elemental analysis, magnetic susceptibility, molar conductance and spectral (IR, NMR and LC-MS) measurements. Salptsmh has also been characterized by single crystal X-ray diffraction. (1)H and (13)C shielding tensors for crystal structure were calculated with GIAO/DFT/B3LYP/6-311++G(d,p) methods in CDCl3. The complexes were found to have general composition [ML2]. The results of elemental analysis showed 1:2 (metal/ligand) stoichiometry for all the complex. Magnetic and spectral data indicate a square planar geometry for Pd(II) complex and a distorted tetrahedral geometry for Co(II) complexes. The ligand and its metal chelates have been screened for their antimicrobial activities using the disk diffusion method against the selected Gram positive bacteria: Bacillus subtilis, Bacillus cereus, Staphylococcus aureus, Enterococcus faecalis, Gram negative bacteria: Eschericha coli, Pseudomonas aeruginosa, Klebsiella pneumonia. The inhibition activities of these compounds on carbonic anhydrase II (CA II) and carbonic anhydrase I (CA I) have been investigated by comparing IC50 and Ki values and it has been found that Pd(II) complex have more enzyme inhibition efficiency than salptsmh and Co(II) complex.

Experimental and computational study on 2,2'-[(1E,2E)-hydrazine-1,2-diylidenedi(1E)eth-1-yl-1-ylidene]diphenol and its Ni(II), Pt(II), Pd(II) complexes

2,2'-[(1E,2E)-hydrazine-1,2-diylidenedi(1E)eth-1-yl-1-ylidene]diphenol and its dimeric, binuclear Ni(II), Pd(II) and Pt(II) metal complexes were synthesized. Hydrazine derivative and its complexes were characterized by elemental analyses, LC-MS, IR, electronic spectra, (1)H and (13)C NMR spectra, conductivity and magnetic measurements. 1H and 13C shielding tensors for crystal structure were calculated with GIAO/DFT/B3LYP/6-311++G(d,p) methods in CDCl3. The vibrational band assignments were performed at B3LYP/6-311++G(d,p) theory level combined with scaled quantum mechanics force field (SQMFF) methodology. The antibacterial activities of synthesized compounds were studied against some Gram-positive and Gram-negative bacteria by using the microdilution and disk diffusion method. As the antibacterial activity results evidently show, the compound possessed a broad spectrum of activity against the tested bacteria.