Sensing application and mechanism of organic-inorganic nanocomposites

As one of research hotspots, organic-inorganic nanocomposite materials combine virtues from both components at microcosmic level, achieving desired function and performance. This paper prepared a series of probe materials for Hg(Ⅱ), Cu(Ⅰ), Fe(Ⅲ) etc. using starting chemicals of rhodamine, triphenylamine and emissive metal complexes. These probes were embedded into proper matrixes to construct composite materials, realizing naked-eye colourimetric sensing towards metal and anion ions. Different ions and their sequence led to spectral variations of absorption and emission spectra. Molecular logic gates were simulated using metal ions or oxygen as input, absorption/emission as output, respectively, widening application of these probes. Hexagonal β-NaYF₄ nanocystals were prepared and used as excitation source to eliminate background light interference. Probe molecules were covalently grafted onto these silica coated β-NaYF₄ nanocystals, giving core-shell structured up-conversion sensing composites. Upon IR radiation, up-conversion green light was observed, showing good selectivity and sensitivity to metal ions with linear response. Above up-conversion and sensing features made corresponding nanocomposites a promising candidate in analytical chemistry and biochemistry.