ИСТИНА

NIR-emitting phosphorous based on lanthanide coordination compounds (CCs) are promising materials for sensors, since their radiation enters the windows of biological and telecommunication transparency, and the narrowness of emission bands and long-term lifetime provides the possibility of detecting a high-accuracy signal. To achieve low resolution, high intensity of the sensory signal is also necessary. However, for NIR-emitters, even when using an effective absorbing ligand, the intensity is insufficient for practical applications. An increase in the efficiency of NIR-luminescence becomes possible to minimize many processes of extinguishing: oscillatory, concentration extinguishing and extinguishing on defects. Speaking about CCs with organic ligands, the last type is rarely considered, and it is believed that morphology almost does not affect luminescence. In our works, however, we noticed that this is not so, and the purpose of this study was to identify the influence of morphology on the fluorescent properties of the ytterbium CCs. As a ligand, a pyrenate-ion, was chosen. It has a low energy of a triplet state (T1 = 14 600 cm-1), so we expected that it would ensure the effective sensitization of Yb3+ ion, high absorption and minimal vibrational quenching. Despite this, Yb(pyr)3 complex, obtained at room temperature, had extremely weak luminescence. The variation of the synthesis time and gadolinium fraction in the complex, made it possible to obtain samples with high crystalline and record for coordination compounds of ytterbium in powder a quantum yield value of 6%. Thanks to the obtained data on the dependence of the morphology of the powder and, as a result, the intensity of the luminescence, on the conditions of the synthesis and composition of the sample, it was also possible to get compounds with the luminescence of two ions: ytterbium and neodymium. Their high thermal stability made it possible to obtain fluorescent thermometers with a working range of 35-250 °С C for 10 measurement cycles and a sensitivity up to 3%K-1.