Tuning White Light Emission in Dinuclear Phenoxo Bridged Dy Complexes.

A new series of dinuclear dysprosium(III) complexes, [Dy(L)(NO)(MeOH)] (), [Dy(L)(NO)(DMF)]·2DMF (), [Dy(L)(NO)(DMF)]·2DMF (), and [Dy(L)(NO)(DMF)] (), with 2,2'-[[(2-pyridinylmethyl)imino]di(methylene)]bis(4-R-phenol), where R = CH, Cl, and CHO, were investigated as potential white light emitters. All octacoordinated dysprosium(III) are phenoxo-bridged species and have a similar coordination environment. Nevertheless, has a MeOH ligand molecule, while for - a DMF ligand replaces that of MeOH. The nature of the coordinated solvent molecule plays an important role in the behavior of the thermal dependence of the / (yellow/blue) emission ratio of the Dy complexes (: F → H, yellow and : F → H, blue transitions),, since for the variation of this ratio is significant, while for the other Dy complexes with DMF as ligand the ratio remains constant within experimental error. At room temperature the CIE (Commission International d'Eclairage) color coordinates for the Dy complexes, (0.286, 0.317), (0.302, 0.324), and (0.322, 0.348) are close to the NTSC (National Television System(s) Committee) standard value for white color. Varying the temperature from 16 to 300 K the CIE coordinates for change from the blueish to white region of the chromaticity diagram, while those of present an inverse thermal dependence as compared to . The CCT (Correlated Color Temperature) values at room temperature for (8384 K), (17235 K), and (5948 K) permit us to consider these complexes as candidates for white cold light emitters, the high value of being uncommon. For and the CCT values vary strongly with temperature, showing a decrease with increasing temperature for , and an increase with increasing temperature for , thus making evident the influence on the photophysical properties of the nature of the coordinated solvent molecule in these complexes.