China
is a rare earth resource, the development of rare earth applications
with unique advantages in resources, rare earth materials has become
energy-efficient lighting, display and information industry development
process indispensable basic materials. As
the rare earth ion emission band narrow, pure color, visible area wide,
high efficiency of light absorption and conversion, up to millisecond
long excited state life, luminous stability, high temperature. Based on these excellent performance, research and development of rare
earth luminescent materials will bring energy saving and environmental
protection, color purity, high strength and long life of the light
source applications to promote the lighting display industry upgrade
optimization.
Recently,
the University of Changzhou Institute of Petrochemical Technology
Professor Wu Daju (click to view the introduction) research team
designed a two-dimensional interchangeable grille MOF frame material,
the use of MOF microporous structure, to achieve a rare earth ion
adsorption and fluorescent light color adjustment application. The
change of the LLCT excited fluorescence of the ligand involved in the
metal ion was optimized by changing the mixed ligand strategy, and the
structure of the MOF with high fluorescence emission was constructed.
The variable temperature fluorescence study showed that the structure
had high sensitivity and thermal response. 2.5%
at room temperature increased to 18.4% of the liquid nitrogen
temperature, and the chromaticity coordinates shifted from (0.221,
0.211) to (0.176, 0.147), close to the saturated blue emission
characteristics.
Figure 1. Grid MOF interpenetrating structure and temperature dependent fluorescence spectra
In addition,
they can adsorb rare earth ions into the MOF microporous structure
through the basic and chemical principles of the host and guest in the
water dispersion system. The Ln @ MOF composites can form rare earth
ions in the aqueous phase or solid state. By adjusting the Eu3 + Tb3 + stoichiometric ratio, to achieve the light color almost perfect three primary colors (RGB) composite white light emission. They
further utilize the height of the three-color light and the energy
transfer between the host and the guest, between the rare earth ions and
the fluorescence response of the MOF main body to the temperature
stimulus sensitivity, such as exhibiting complex white light at room
temperature (0.333, 0.328), and the liquid
nitrogen temperature exhibited blue light emission (0.180, 0.126), which
exhibited excellent thermal sensing properties.
Figure 2. Fluorescence response spectra of MOF materials to rare earth ions
Figure 3. Temperature-stimulated emission spectra and chromaticity coordinates of rare earth composite MOF materials
This work not only
provides a new way for the preparation of novel luminous function MOF,
but also in the regulation of rare earth ion light mode also has
important reference value. The work was completed
under the auspices of the National Natural Science Foundation of China
and the Jiangsu Provincial Advantage Program, published in full text on
Inorganic Chemistry.
