Abstract
Hydro(solvo)thermal reactions of Cd(NO3)2, N-(pyridin-3-ylmethyl)-4-(pyridin-4-yl)-1,8-naphthalimide (NI-mbpy-34), and 5-bromobenzene-1,3-dicarboxylic acid (Br-1,3-H2bdc) afforded a luminescent coordination polymer, {[Cd(Br-1,3-bdc)(NI-mbpy-34)(H2O)]∙2H2O}n (1). Single-crystal X-ray diffraction analysis showed that 1 features a two-dimensional (2-D) gridlike sql layer with the point symbol of (44·62), where the Cd(II) center adopts a {CdO5N2} pentagonal bipyramidal geometry. Thermogravimetric (TG) analysis confirmed the thermal stability of 1 up to about 340 °C, whereas XRPD patterns proved the maintenance of crystallinity and framework integrity of 1 in CH2Cl2, H2O, CH3OH, and toluene. Photoluminescence studies indicated that 1 displayed intense blue fluorescence emissions in both solid-state and H2O suspension-phase. Owing to the good fluorescent properties, 1 could serve as an excellent turn-off fluorescence sensor for selective and sensitive Cr(VI) detection in water, with LOD = 15.15 μM for CrO42− and 14.91 μM for Cr2O72−, through energy competition absorption mechanism. In addition, 1 could also sensitively detect Cr3+, Fe3+, and Al3+ ions in aqueous medium via fluorescence-enhancement responses, with LOD = 2.81 μM for Cr3+, 3.82 μM for Fe3+, and 3.37 μM for Al3+, mainly through an absorbance-caused enhancement (ACE) mechanism.
Highlights
Accepted: 22 November 2021With the advanced development of modern society, rapid industrial and agricultural productions and rich human activities have increasingly brought about severe chemical pollution
Single-crystal X-ray structure analysis reveals that the crystal structure of 1 belongs to the triclinic space group
2.393(2) Å, Cd1–O6#2 = 2.389(2) Å, #2, x − 1, y, z) chelating modes and one 4-pyridyl nitrogen atom from one NI-mbpy-34 ligand (Cd1–N3 = 2.301(2) Å), while the two apical positions are located by one coordination water molecule
Summary
With the advanced development of modern society, rapid industrial and agricultural productions and rich human activities have increasingly brought about severe chemical pollution. Heavy metal ions are well-known poisonous contaminants in water due to their high toxicity, which could cause serious environmental and ecological harm and cause a detrimental effect on human health [2]. The sensing and detection of chemical pollutants has attracted tremendous interest from many researchers Benefitting from their unique merits, low-cost, easy manipulation, instant, visual identification, excellent sensitivity, and high selectivity [7,12], fluorescence based detection has gained considerable attention among various conventional instrumental techniques. We have made advances in fluorescence detection of hazardous chemical contaminants by using luminescent organic–inorganic hybrid materials as sensory platforms [30,31,32,33,34,35,36,37,38,39]. The remarkable emission properties make 1 a functional multiresponsive fluorescence sensor for Cr(VI) oxyanions detection via a quenching effect, and Cr(III), Fe(III), and Al(III) sensing via an enhancement response in aqueous medium, with high sensitivity and remarkable selectivity
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