Na-Ln Heterometallic Coordination Polymers: Structure Modulation by Na Concentration and Efficient Detection to Tetracycline Antibiotics and 4-(Phenylazo)aniline.

On the basis of the lanthanide metalloligand [Ln(ODA)] (HODA = oxydiacetic acid), three new Na-Ln heterometallic coordination polymers, [Ln(ODA)Na] [Ln = Eu () and Gd ()] and [Tb(ODA)Na(HO)] (), had been assembled by adjusting the concentration of Na ions in the reaction system. The investigations of fluorescence sensing showed that could be a ratiometric probe to detect tetracycline () and oxytetracycline () with high sensitivity and low detection limits, 71.92 ppb for the former and 45.54 ppb for the latter, and could selectively sense 4-(phenylazo)aniline through the turn-off pathway with 14.59 ppb of detection limits. Moreover, the competing and circulating experiments indicated that both and had satisfactory antiinterference and recyclability for the corresponding analytes. All of these results implied that and should be potential fluorescent sensors for the detection of / and 4-(phenylazo)aniline, and the possible sensing mechanism had also been discussed in depth.