Cyclen-Derived Chelators for High-Purity Rare Earth Separation
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Solution Overview
Problem
Current separation methods for rare earth and s-, p-, d-block metals are inefficient and complex, particularly for achieving no-carrier-added (NCA) radionuclides needed in medical applications, due to the chemical similarity of these metals and the use of weak interactions that allow rapid exchange, leading to contamination and difficulty in achieving high purity.
Innovation Solution
Employing strong chelators structurally derived from cyclen that form kinetically inert chelates, allowing for chromatographic separation based on small differences in ionic radii, enabling the use of conventional chromatography and instrumentation while preventing contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If weak interactions (ionic interactions, solvation, coordination) are used for separation, then rapid exchange of metal ion surroundings is achieved, but separation efficiency is insufficient due to contamination from trace metals and inability to achieve NCA radionuclides
Solution Approach 1:
The patent changes the interaction strength parameter by introducing strongly chelating ligands (DOTA and its derivatives) that form kinetically inert complexes with metal ions. This transforms the separation mechanism from weak ionic interactions to strong coordination bonds, enabling both rapid separation and high purity NCA radionuclides by preventing re-exchange and contamination during the separation process
Solution Approach 2:
The patent uses composite chelating agents combining DOTA macrocycle with various functional groups (hydroxamic acid, carboxylic acid, phosphonic acid) to create ligands that simultaneously provide strong chelation for kinetic inertness and specific coordination geometry for selective separation of rare earth radionuclides from parent nuclides and byproducts
2Stability of the object's composition
If strongly chelating ligands (e.g., DOTA) are used, then kinetically inert complexes are formed, but rapid exchange necessary for separation is prevented
Solution Approach 1:
The patent applies preliminary complexation by pre-forming kinetically inert DOTA-chelated radionuclides before separation. The radionuclides are first chelated by DOTA ligands to form stable complexes, then these pre-formed complexes are separated using chromatographic methods. This preliminary chelation action ensures kinetic inertness is established before the separation process begins, allowing the use of strong chelators without preventing separation
Solution Approach 2:
The patent introduces a mediator approach where DOTA acts as an intermediary chelating agent that temporarily binds the radionuclide in a kinetically inert complex during the separation process. The stable DOTA-radionuclide complex serves as an intermediate form that can be selectively retained or eluted on chromatographic media, enabling separation while maintaining kinetic inertness throughout the process
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 method provides fast and simplified separation of rare earth and s-, p-, d-block metals, achieving high purity and stability of radionuclides, suitable for medical applications by forming chelates that are resistant to exchange during chromatography.
Implementation Method 1
Employing strong chelators structurally derived from cyclen that form kinetically inert chelates
Implementation Method 2
chromatographic separation of rare earth elements and/or s-, p-, d-block metals from a mixture of metal ions
Data Source
AI summary
The present invention relates to compounds of general formula (I), wherein:X is selected from a group consisting of H; OH; SH; CF3; F; Cl; Br; I; C1 to C6 alkyl; C1 to C6 alkyloxy; C1 to C6 alkylthio; NH2; C1 to C6 alkylamino; di(C1 to C6 alkyl)amino; NO2; COOH;Y is selected from a group consisting of nitrogen; carbon, which can optionally be substituted with OH or F; oxygen; N-oxide;Z atoms are independently selected from the group consisting of carbon and nitrogen, whereas R is only present when the valence of Z allows it; and whereas at least one Z is carbon; and whereas n=0 or 1;L is covalent bond or —C(O)—;R are independently selected from the group consisting of H; C1 to C6 alkyl; C1 to C6 alkyloxy; C6 to C10 aryloxy; benzyloxy; C1 to C6 alkylthio; C6 to C10 arylthio; F; Cl; Br; I; OH; SH; NH2; C1 to C6 alkylamino; di(C1 to C6 alkyl)amino; C1 to C6 acylamino; di(C1 to C6 acyl)amino; C6 to C10 arylamino; di(C6 to C10 aryl)amino; CN; OH; nitro; COORn, C(O)NHRn, C(O)N(Rn)2, wherein Rn is independently H or C1 to C10 alkyl or C6 to C10 aryl; orneighboring two R together with neighboring two Z form a six-membered ring, optionally substituted with one or more substituents independently selected from the group consisting of OH, SH, CF3, F, Cl, Br, I, C1 to C6 alkyl, C1 to C6 alkyloxy, C1 to C6 alkylthio, NH2, C1 to C6 alkylamino, di(C1 to C6 alkyl)amino, NO2, COOH, COORn, C(O)NHRn, C(O)N(Rn)2, wherein Rn is independently H or C1 to C10 alkyl or C6 to C10 aryl; orX and the neighboring carbon, Z and R form a six-membered ring, optionally substituted with one or more substituents independently selected from the group consisting of OH, SH, CF3, F, Cl, Br, I, C1 to C6 alkyl, C1 to C6 alkyloxy, C1 to C6 alkylthio, NH2, C1 to C6 alkylamino, di(C1 to C6 alkyl)amino, NO2, COOH, COORn, C(O)NHRn, C(O)N(Rn)2, wherein Rn is independently H or C1 to C10 alkyl or C6 to C10 aryl;R1 is selected from the group consisting of H; —(C1 to C6 alkyl); benzyl, which can be optionally substituted independently with one or more substituents selected from nitro, OH; —(C1 to C2 alkylen)COOH, the alkylen of which can optionally be substituted with C1 to C6 alkyl; —CH2P(O)(OH)2; —CH2P(O)(OH)(C1 to C6 alkyl);for chromatographic separation of rare earth elements and/or s-, p-, d-metals, as well as to the method of the separation of rare earth elements.