Rare Earth Metal Complexes for Long UV Excitation
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Solution Overview
Problem
Existing rare earth metal complexes have poor solubility in water, insufficient stability for inkjet applications, and limited excitation range to short UV wavelengths, making them unsuitable for various printing and security applications.
Innovation Solution
Development of rare earth metal complexes of 5,6-diaryl-3-(2-pyridyl)-1,2,4-triazines and europium dipyridyl nitrates with diketone dopants, which are soluble in water and organic solvents, exhibit bright fluorescence in the visible region under long UV wavelengths, and demonstrate high lightfastness, enabling their use in inkjet printing and security applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If known rare earth metal complexes are used, then fluorescence emission in the visible region is achieved, but solubility in water is poor
Solution Approach 1:
The patent modifies the chemical structure of the ligand by introducing sulfonic acid groups (–SO3H) at specific positions on the triazine ring. This parameter change in the molecular structure dramatically improves water solubility while maintaining the complex's fluorescence properties and stability, directly resolving the contradiction between solubility and stability.
Solution Approach 2:
The invention creates a composite coordination complex combining rare earth metal ions with specially designed triazine ligands containing both hydrophilic sulfonic acid groups and hydrophobic aromatic regions. This composite structure enables simultaneous achievement of water solubility, stability, and fluorescent emission.
2Use of energy by moving object
If known rare earth metal complexes are used, then fluorescence emission is achieved, but excitation is limited to UV-C or short UV wavelength range
Solution Approach 1:
The patent changes the energy level parameters of the ligand through structural modification (introducing electron-withdrawing sulfonic acid groups and extending conjugation with phenyl and pyridyl groups). This shifts the absorption spectrum to longer wavelengths, enabling excitation in the long UV range (350-390 nm) while maintaining strong visible region fluorescence emission.
3Reliability
If known rare earth metal complexes are used, then fluorescence emission is achieved, but stability in water is insufficient for inkjet applications
Solution Approach 1:
The introduction of sulfonic acid groups creates strong metal-ligand coordination bonds with rare earth metals, significantly enhancing the complex's stability in aqueous environments. This structural parameter change enables the complex to withstand the conditions required for inkjet printing applications.
4Quantity of substance
If triazine ligands with multiple sulfonic acid groups are introduced to improve solubility, then water solubility increases, but complex structure becomes more complicated
Solution Approach 1:
The ligand structure is segmented into distinct functional modules: the triazine core, sulfonic acid groups for solubility, pyridyl groups for coordination, and phenyl groups for conjugation. This modular segmentation achieves the desired solubility and stability while maintaining a systematic and manageable molecular architecture.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The new complexes show improved solubility and stability, with narrow emission spectra and high lightfastness, making them suitable for diverse printing systems and security applications, including inkjet printing and security inks, without the need for fluorine groups, thus being environmentally friendly.
Implementation Method 1
Certain rare earth metal complexes that are invisible under normal lighting conditions, yet produce strong emissions in the visible region when irradiated with ultraviolet (UV) light
Implementation Method 2
The rare earth metal complexes of this disclosure may be used as pigments in ink compositions for printing systems and for security applications
Data Source
AI summary
There is provided rare earth metal complexes of formula (I):wherein M is a cation, RE is a rare earth metal; X is a counter anion; and R1, R2, R3, and R4 are each independently selected from hydrogen, alkyl of 1-8 carbon atoms, aryl, halo, and alkoxy. Also provided is a composition of europium bis(2,2′-bipyridine-N,N′)-trinitrate with a diketonate dopant. The disclosure also provides processes for preparing the rare earth metal complexes. A mark comprising the rare earth metal complexes, and a method of applying the mark, are disclosed. The rare earth metal complexes may be used in printing systems, and for security applications.