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We designed and synthesized a fluorescent "turn-on" and colorimetric chemosensor ((E)-1-((p-tolylimino)methyl)naphthalen-2-ol) SB. The structure of the synthesized chemosensor was investigated by 1H NMR, FT-IR, and fluorescence spectroscopy, and its sensing properties were studied toward Mn2+, Cu2+, Pb2+, Cd2+, Na+, Ni2+, Al3+, K+, Ag+, Zn2+, Co2+, Cr3+, Hg2+, Ca2+, and Mg2+. SB showed an excellent colorimetric (yellow to yellowish brown) in MeOH and fluorescence "turn-on" sensing response to Cu2+ in MeOH/Water (10/90, v/v) media. The sensing mechanism of SB toward Cu2+ was investigated by FT-IR, 1H NMR titration, DFT studies, and Job's plot analysis. The detection limit was calculated to be very low 0.0025 µg mL−1 (0.0025 ppm). Furthermore, the test strip containing SB also showed excellent selectivity and sensitivity toward Cu2+ in a solution medium and when supported on a solid medium. [ABSTRACT FROM AUTHOR]

[Display omitted] The nanobiotechnology era has sparked interest in the green synthesis of stable silver nanoparticles (Ag-NPs) without hazardous chemicals. As a result, the current study used chitosan-salicylaldehyde Schiff base (CSB) as a non-toxic, reducing and stabilizing agent to prepare stable silver nanoparticles. The characterization of Ag-NPs impregnated chitosan-salicylaldehyde Schiff base was fulfilled using UV-Vis, FTIR, XRD and TEM studies. The absorption band present around 425 nm in UV-Vis spectra indicated the formation of Ag-NPs. The appearance of a new band for the C N bond, deduction in the intensity of the C O group of salicylaldehyde and N H group of chitosan confirmed the formation of Schiff base and Ag-NPs in FTIR analysis. XRD pattern revealed the orientation and crystalline nature of Ag-NPs with 2θ at 38°, 46° and 54° related to Ag-NPs (JCPDS No. 04-0783), whereas the peak at 2θ = 27° associated with CSB. The total porosity of 53.24% was determined using the liquid displacement method. The CSB-Ag-NPs have good scavenging activity (46.25% and 49.35% activity in DPPH assay and H 2 O 2 assay), great antibacterial (zone of inhibition 17 mm and 19 mm for E-Coli and Pseudomonas sp.), antifungal (18 mm for P. notatum), and anti-larvicidal activity, according to biological assessments. The synthesised Ag-NPs were non-toxic to marine ecosystems in a safety bioassay test. [ABSTRACT FROM AUTHOR]

The present paper provides a description of the design, characterization, and use of a Hg2+ selective electrode (Hg2+–SE) for the determination of Hg2+ at ultra-traces levels in a variety of real samples. The ionophore in the proposed electrode is a new Schiff base, namely 4-bromo-2-[(4-methoxyphenylimino)methyl]phenol (BMPMP). All factors affecting electrode response including polymeric membrane composition, concentration of internal solution, pH sample solution, and response time were optimized. The optimum response of our electrode was obtained with the following polymeric membrane composition (% w/w): PVC, 32; o-NPOE, 64.5; BMPMP, 2 and NaTPB, 1.5. The potentiometric response of Hg2+–SE towards Hg2+ ion was linear in the wide range of concentrations (9.33 × 10–8−3.98 × 10–3 molL–1), while, the limit of detection of the proposed electrode was 3.98 × 10–8 molL–1 (8.00 μg L–1). The Hg2+–SE responds quickly to Hg2+ ions as the response time of less than 10 s. On the other hand, the slope value obtained for the developed electrode was 29.74 ± 0.1 mV/decade in the pH range of 2.0−9.0 in good agreement with the Nernstian response (29.50 mV/decade). The Hg2+–SE has relatively less interference with other metal ions. The Hg2+–SE was used as an indicator electrode in potentiometric titrations to estimate Hg2+ ions in waters, compact fluorescent lamp, and dental amalgam alloy and the accuracy of the developed electrode was compared with ICP–OES measurement values. Moreover, the new Schiff base (BMPMP) was synthesized and characterized using ATR–FTIR, elemental analysis, 1H NMR, and 13C NMR. The PVC membranes containing BMPMP as an ionophore unloaded and loaded with Hg(II) are reported by scanning electron microscope images (SEM) along with energy-dispersive X-ray spectroscopy (EDX) spectra. [ABSTRACT FROM AUTHOR]

[Display omitted] • Synthesis of a novel Schiff base-based off–on-off chemosensor SBC-1. • Applied the synthesized chemosensor for the detection of Cu2+ ions. • Applied the SBC-1-Cu2+ complex for the detection of 2,4-D. • Study the performance of SBC-1 and SBC-1-Cu2+ in various water samples. The development of selective and sensitive chemosensors for the recognition of metal ions and pesticides is very important in environmental monitoring, industrial quality control, and public health. In this study, we present a novel Schiff base-based off–on-off chemosensor SBC-1 for the specific and sensitive detection of Cu2+ ions and 2,4-dichlorophenoxyacetic acid (2,4-D). The Schiff base chemosensor forms a complex with Cu2+ (SBC-1-Cu2+), leading to characteristic color changes from bright yellow to light yellow and significant enhancement in fluorescence emission at 584 nm. The resulting complex was further applied for the determination of 2,4-D. The detection limit was calculated to be 0.0028 ppm (0.044 µM) for Cu2+ and 0.0327 ppm (0.147 µM) for 2,4-D. The analytical performance of the Schiff base chemosensor is evaluated in various water samples (pond, lake and tap water) and demonstrating its robustness and reliability for practical use. The percent recovery from these samples was found to be 92.100. ± 0.18 % to 105.333 ± 0.34 % at various levels. Additionally, the chemosensor response mechanisms and binding interactions with heavy metal ions are elucidated through spectroscopic studies. The chemosensor and its complex exhibit remarkable selectivity, providing distinct responses toward Cu2+ and 2,4-D even in the presence of different interfering species. [ABSTRACT FROM AUTHOR]

In this study, we have synthesized a novel Schiff base-centered chemosensor, designated as SB, with the chemical name ((E)-1-(((6-methylbenzo[d]thiazol-2-yl) imino)methyl)naphthalen-2-ol). This chemosensor was structurally characterized by FT-IR, 1H NMR, UV-Vis and fluorescence spectroscopy. After structural characterization the chemosensor SB was subsequently employed for the detection of Cu2+ and Ag+, using fluorescence spectroscopy. The chemosensor SB showed excellent ability to recognize the target metal ions, leading to fluorescence enhancement and color change from yellow to yellowish orange for Cu2+ and yellow to radish for Ag+ ions. The detection capabilities of this chemosensor were impressive, showing excellent selectivity and an exceptionally low detection limit of 0.0016 µM for Cu2+ and 0.00389 µM for Ag+. Most notably, our approach enables the quantitative detection both metal ions in different water and soil samples at trace level. This achievement holds great promise for analytical applications and offers significant contributions to the field of chemical sensing and environmental protection. [ABSTRACT FROM AUTHOR]