Fluoride selective colorimetric sensor based on cefetamet pivoxil drug

Synthesis, characterization, optical properties, biological activity and theoretical studies of a 4 nitrobenzylidene) amino) phenyl)imino)methyl)naphthalen-2-ol -based fluorescent Schiff base

A new Schiff base, 1-(E)-(4-((E) 4nitrobenzylidene) amino) phenyl)imino) methyl)naphthalen-2-ol (4NMN), was prepared from the reaction of p-phenylenediamine with 2-hydroxy-1-naphthaldehyde and 4-nitrobenzaldehyde and characterized with spectroscopic analysis. UV-VIS and NMR. Frontier molecular orbitals, molecular electrostatic potential, and chemical reactivity descriptors of the synthesized compound were studied using molecular modeling methods. The antibacterial and antifungal activities of the Schiff base were studied for its minimum inhibitory concentration. The compound showed a higher effect on yeast than against bacteria. Density functional theory (DFT) calculations were performed to study the mechanism of reaction for the synthesis of 4NMN, and the results were consistent with the experimental findings. 4NMN exhibited moderate antibacterial and antifungal activities and demonstrated higher inhibition potential against different resistant strains compared to the reference drug gentamycin. The absorption and fluorescence spectra of 4NMN were measured in different solvents, and the effect of relative polarity and acidity on the medium was observed. An inner filter effect was observed at high concentrations, and the compound showed considerable fluorescence enhancement with increasing medium viscosity and fluorescence quenching by the addition of traces of Cr1+ and Cu2+. Additionally, molecular docking studies were conducted to investigate the efficiency of antibacterial and antifungal targets.

A comparative performance evaluation of cephalosporin's drugs for fluoride recognition

In this manuscript, readily available cephalosporin's drugs cefuroxime axetil (L1) cefpdoxime proxetil (L2), and cefditoren pivoxil (L3) possess dihydrothiazine ring as signaling unit, and -NH groups as the binding site were used for the sensing of fluoride (F^-) ions. In the presence of F^-, the drug selectively portrayed a naked-eye detectable color change from colorless. The binding constant of 1:1 stoichiometric complex of L1, L2, and L3 with F^- was found to be 2.36 × 10⁴ M^-1, 2.44 × 10³ M^-1 and 1.02 × 10⁴ M^-1 respectively. The lowest detection limit (LOD) of F^- was found to be 11 µM (209 ppb) with drug L1 and L2. The binding mechanism of the drug with F^- was studied by ¹H and ¹⁹F nuclear magnetic resonance (NMR) spectral titration, electrospray ionization mass spectra (ESI-MS) analysis, and density functional theory (DFT) studies. The presence of F^- was monitored in various spiked water and Colgate toothpaste samples. Overall, cephalosporin's drug demonstrates a promising potential for the detection of F^- ions in the semi-aqueous phase.

Substituent effect on colorimetric detection of biologically and environmentally relevant anions: Insight in real-life applications

A new set of chromogenic anion receptors R1-R4 have been synthesized with a different substituent, including electron withdrawing (nitro moiety in R1), conjugated group (naphthyl in R2), and electron donating (methyl in R3), respectively. The receptors R1-R4 exhibited very good sensitivity towards the F^- and AcO^- anions in the DMSO. In addition, R1 showed selectivity towards H₂PO₄^- ions over other tested anions. R1 especially acted as an effective sensor for sodium salts of F^-, AcO^-, AsO₂^-, and AsO₄^2- ions in an aqueous medium due to the presence of two electron-withdrawing nitro substituents, which showed hydrogen bond donor tendency and acidity of the OH proton. This result indicates that R1 is highly capable of competing with an aqueous medium to detect anions without counter Na⁺ ion interference. Interestingly, R1 displays solvatochromic property in the presence of AcO^- ions in different aprotic solvents. Additionally, the receptor R1 shows high binding affinity towards AcO^- ions in the buffer medium (DMSO: HEPES, 9:1 v/v), which displayed remarkable colour change from pale yellow to blue with a large ∆λ_{red shift} of 170 nm. The CV studies reveal the deprotonation of the -NH proton upon interaction with the AcO^- ions. The receptor R1 is subjected to practical application to sense F^- and AsO₂^- ions using the test strip. In addition, the receptor R1 proves itself as a potential applicant for the detection of F^- ions quantitatively in commercially available mouthwash.

Design, synthesis and ¹H NMR study of C3v-symmetric anion receptors with urethane-NH as recognition group

C3v-Symmetric anion receptors 3 and 4 with urethane groups were synthesized by using trindane triol as tripodal molecular framework. In (1)H NMR titration study, the receptors showed noticeable downfield shift/disappearance of the urethane-NH peak in presence of H2PO4(-) and F(-) due to the host-guest complexation occurred through multiple hydrogen bonding and/or the deprotonation of urethane-NH groups. Other tested anions such as Cl(-), Br(-), HSO4(-), and NO3(-) showed either no or negligible chemical shift of the urethane groups. The deprotonation event in 4 allowed selective detection of F(-) by perceptible color change from colorless to yellowish-red with the appearance of a new charge transfer absorption band at 450 nm.

A simple ratiometric and colorimetric chemosensor for the selective detection of fluoride in DMSO buffered solution

A derivative of squaramide (cyclobuta[b]quinoxaline-1, 2(3H, 8H)-dione) has been synthesized for the ratiometric and colorimetric sensing of F(-) in aqueous solution in competitive fashion. With F(-), probe 1 showed a highly selective naked-eye detectable color change along with a characteristic UV-Vis absorbance over other tested ions, which probably originates from the deprotonation occurred between 1 and F(-), as proved by the (1)H NMR titration experiments and DFT calculations.

Anion selective chromogenic and fluorogenic chemosensor and its application in breast cancer live cell imaging

A novel anion selective chromogenic and fluorogenic chemosensor (L) bearing catechol and phenol groups was developed. The sensorLwas tested for live breast cancer cell imaging and can be applied to the breast tumour diagnosis.