Idiosyncatic recognition of Zn and CN using pyrazolyl-hydroxy-coumarin scaffold and live cell imaging: depiction of luminescent Zn(II)-metallocryptand.

Multi-responsive and selective sensor design is one of the stimulating research areas in the sensors field. We have designed a pyrazolyl-hydroxy-coumarin scaffold, 7-hydroxy-4-methyl-8-(((5-phenyl-1-pyrazol-3-yl)imino)methyl)-2-chromen-2-one (HL) and characterized it by spectroscopic techniques (H NMR, C NMR, ESI-MS, IR). The single crystal X-ray diffraction measurement confirms the molecular structure of the probe. It shows the selective sensing of Zn in the presence of sixteen other cations with 'Turn On' approach through the enhancement of green florescence (( = 499 nm; = 390 nm) in CHCN/HO (99 : 1, v/v; HEPES buffer, pH 7.5) medium with the limit of detection (LOD) of 34.76 nM. The structural depiction of the isolated Zn complex reveals cage like metallocryptand cyclic hexamer, [ZnL] with 30.9% void of cavity along the crystallographic axis of approximate dimension of 7.502 × 7.050 × 7.068 Å. The diffusion NMR study reveals only one type of complex in the solution, having 1 : 1 composition, , Zn : HL, which affirms the isolated form of the complex. On the other hand, the receptor, HL, recognizes the very noxious anion CN out of sixteen anions. The product identification using spectroscopic techniques supports the nucleophilic addition of CN across the exocyclic imine (CN) bond, which shows blue emission (( = 447 nm; = 390 nm), and the LOD was 19.91 nM. The composition of [HL-Zn] and [HL-CN] was established by H NMR titration, Job's method, ESI-MS, and FTIR spectra. The efficacy of the probe was further studied using MTT assay in MDA-MB 231 and WI-38 cell line as well as for the intracellular imaging of Zn and CN using a fluorescence microscope. Flow Cytometry was further performed for the quantitative analysis of Zn distribution in MDA-MB 231 cells.