Nonconjugated Biocompatible Macromolecular Luminogens for Sensing and Removals of Fe(III) and Cu(II): DFT Studies on Selective Coordination(s) and On-Off Sensing

This work reports the design and synthesis of two nonaromatic biocompatible macromolecular luminogens, i.e., 2-(dimethylamino)ethyl methacrylate-co-2-(dimethylamino)ethyl 3-(N-(methylol)acrylamido)-2-methylpropanoate-co-N-(methylol)acrylamide/DMAEMA-co-DMAENMAMP-co-NMA (P1) and methacrylic acid-co-3-(N-(methylol)acrylamido)-2-methylpropanoic acid-co-N-(methylol)acrylamide/MEA-co-NMAMPA-co-NMA (P2), prepared through in situ anchored acrylamido-ester/DMAENMAMP and acrylamido-acid/NMAMPA third comonomers, respectively, in a facile polymerization of two non-luminous monomers in water medium to circumvent the drawbacks related to aggregation-caused quenching of aromatic luminogens. The structures of P1/P2, in situ anchored comonomers, fluorophores, N-branching associated n-π* interactions, and hydrogen bonding assisted aggregation-enhanced emissions are comprehended by nuclear magnetic resonance, Fourier transform infrared (FTIR), X-ray photoelectron spectroscopy (XPS), ultraviolet-visible, thermogravimetric analysis (TGA), dynamic light scattering (DLS), transmission electron microscopy (TEM), fluorescence lifetime, and fluorescence imaging. P1 and P2 are appropriate for sensitive detections/exclusions of Fe(III)/Cu(II) and cell-imaging. The intrinsic fluorescence, on-off sensing, selective coordinations of Fe(III) and Cu(II) with fluorophores, emission quenching mechanisms, and removals of Fe(III) and Cu(II) are investigated by DFT/NTO analyses of P1/P2 and Fe(III)-P1 and Cu(II)-P2 complexes, XPS, and isotherms and kinetics parameters. The excellent biocompatibilities, comparable limit of detections, i.e., 1.70 × 10^-7 and 1.59 × 10^-7 [m], and higher adsorption capacities, i.e., 77.25 and 154.13 mg g^-1 , at low ppm; 303 K; and pH = 7 compel P1/P2 to be acceptable for multipurpose applications.