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A new pyrenylbenzylidene–malononitrile (P2) was successfully synthesized via the Suzuki coupling reaction and Knoevenagel condensation using nano Cu as a catalyst. The compound P2 could detect hydrazine in 10% THF–PBS, pH 7.4, with a limit of detection (LOD) of 19.46 nM. Moreover, the P2–CA nanofibrous sheets were fabricated by combining compound P2 and cellulose acetate. The LOD of P2–CA nanofibrous sheets was found to be 0.02% w/v for hydrazine detection. The quantity of hydrazine vapor was recognized and quantified by analyzing fluorescence images acquired with a smartphone camera and a portable blacklight lamp that generates light with a wavelength of 365 nm using the ImageJ application. The concentration range of 0.025–1% w/v was accurately determined by employing ImageJ for fluorescence image analysis. Both compound P2 and P2–CA nanofibrous sheets are selective for hydrazine. Also, the mechanism of compound P2 and hydrazine was studied via1H NMR titration, FT-IR experiments and DFT calculations. In addition, the P2–CA nanofibrous sheet has the ability to detect hydrazine vapor in actual samples collected from the environment. Hence, the compound P2 and P2–CA nanofibrous sheets have significant promise as highly effective sensors for detecting hydrazine in water across many environments and industries. [ABSTRACT FROM AUTHOR]

The condensation product of 5‐methoxy‐salicylaldehyde with hydrazine hydrate (referred to below as compound 1) was used as a ligand in a cellulose acetate electrospun nanofibrous mat to determine copper ions in aqueous solutions. The electrospun nanofibrous mats, based on cellulose acetate mixed with compound 1, were constructed using an electrospinning method and had a diameter of 260 nm. The sensing nanofibrous mat exhibited a sensitive and selective response for Cu(II) ions over a linear concentration range of 1‐30 µM in a 0.1 M HEPES buffer (pH 7.4) using a colorimeter. The detection limit of the method was 1.04 µM lower than the maximum level of Cu(II) in drinking water (16 µM, as determined by the US Environmental Protection Agency). Additionally, it exhibited high selectivity for Cu(II) ions over 13 other cations. The sensing nanofibrous mat was fully reversible for ethylenediamine tetraacetic acid treatment cycles. Preliminary results indicated the sensitivity and selectivity of the nanofibrous mat for detecting Cu(II) ions by naked‐eye detection from yellow to orange. The reaction product of compound 1 and the Cu(II) ion was studied using X‐ray absorption spectroscopy. The Cu‐coordination number was approximately 5.023 ± 1.42, and the Cu–N distance (R) was 1.986 Å. The nanofibrous mat demonstrated a convenient and straightforward Cu(II) ion‐detection technique in both wastewater and water environments. [ABSTRACT FROM AUTHOR]