Tag: M.W=500-550

Abou, Diane S. published the artcileTowards the stable chelation of radium for biomedical applications with an 18-membered macrocyclic ligand, Recommanded Product: 6,6′-((1,4,10,13-Tetraoxa-7,16-diazacyclooctadecane-7,16-diyl)bis(methylene))dipicolinic acid, the publication is Chemical Science (2021), 12(10), 3733-3742, database is CAplus and MEDLINE.

Targeted alpha therapy is an emerging strategy for the treatment of disseminated cancer. [²²³Ra]RaCl₂ is the only clin. approved alpha particle-emitting drug, and it is used to treat castrate-resistant prostate cancer bone metastases, to which [²²³Ra]Ra²⁺ localizes. To specifically direct [²²³Ra]Ra²⁺ to non-osseous disease sites, chelation and conjugation to a cancer-targeting moiety is necessary. Although previous efforts to stably chelate [²²³Ra]Ra²⁺ for this purpose have had limited success, here we report a biol. stable radiocomplex with the 18-membered macrocyclic chelator macropa. Quant. labeling of macropa with [²²³Ra]Ra²⁺ was accomplished within 5 min at room temperature with a radiolabeling efficiency of >95%, representing a significant advancement over conventional chelators such as DOTA and EDTA, which were unable to completely complex [²²³Ra]Ra²⁺ under these conditions. [²²³Ra][Ra(macropa)] was highly stable in human serum and exhibited dramatically reduced bone and spleen uptake in mice in comparison to bone-targeted [²²³Ra]RaCl2, signifying that [²²³Ra][Ra(macropa)] remains intact in vivo. Upon conjugation of macropa to a single amino acid β-alanine as well as to the prostate-specific membrane antigen-targeting peptide DUPA, both constructs retained high affinity for 223Ra, complexing >95% of Ra²⁺ in solution Furthermore, [²²³Ra][Ra(macropa-β-alanine)] was rapidly cleared from mice and showed low 223Ra bone absorption, indicating that this conjugate is stable under biol. conditions. Unexpectedly, this stability was lost upon conjugation of macropa to DUPA, which suggests a role of targeting vectors in complex stability in vivo for this system. Nonetheless, our successful demonstration of efficient radiolabeling of the β-alanine conjugate with ²²³Ra and its subsequent stability in vivo establishes for the first time the possibility of delivering [²²³Ra]Ra²⁺ to metastases outside of the bone using functionalized chelators, marking a significant expansion of the therapeutic utility of this radiometal in the clinic.

Chemical Science published new progress about 1128304-86-8. 1128304-86-8 belongs to pyridine-derivatives, auxiliary class Pyridines, name is 6,6′-((1,4,10,13-Tetraoxa-7,16-diazacyclooctadecane-7,16-diyl)bis(methylene))dipicolinic acid, and the molecular formula is C26H36N4O8, Recommanded Product: 6,6′-((1,4,10,13-Tetraoxa-7,16-diazacyclooctadecane-7,16-diyl)bis(methylene))dipicolinic acid.

Referemce:
https://en.wikipedia.org/wiki/Pyridine,
Pyridine | C5H5N – PubChem

Roca-Sabio, Adrian published the artcileThe effect of ring size variation on the structure and stability of lanthanide(III) complexes with crown ethers containing picolinate pendants, Synthetic Route of 1128304-86-8, the publication is Dalton Transactions (2011), 40(2), 384-392, database is CAplus and MEDLINE.

The coordination properties of the macrocyclic receptor N,N’-bis(6-carboxy-2-pyridylmethyl)-1,10-diaza-15-crown-5 (H₂bp15c5) towards the lanthanide ions are reported. Thermodn. stability constants were determined by pH-potentiometric titration at 25° in 0.1M KCl. A smooth decrease in complex stability is observed upon decreasing the ionic radius of the Ln^III ion from La [log K_LaL = 12.52(2)] to Lu [log K_LuL = 10.03(6)]. Luminescence lifetime measurements recorded on solutions of the Eu^III and Tb^III complexes confirm the absence of inner-sphere H₂O mols. in these complexes. ¹H and ¹³C NMR spectra of the complexes formed with the diamagnetic La^III metal ion were obtained in D₂O solution and assigned with the aid of HSQC and HMBC 2-dimensional heteronuclear experiments, as well as standard 2-dimensional homonuclear COSY and NOESY spectra. The ¹H NMR spectra of the paramagnetic Ce^III, Eu^III and Yb^III complex suggest nonadentate binding of the ligand to the metal ion. The syn conformation of the ligand in [Ln(bp15c5)]⁺ complexes implies the occurrence of two helicities, one associated with the layout of the picolinate pendant arms (absolute configuration Δ or Λ), and the other to the five five-membered chelate rings formed by the binding of the crown moiety (absolute configuration δ or λ). A detailed conformational anal. performed with the aid of DFT calculations (B3LYP model) indicates that the complexes adopt a Λ(λδ)(δδλ) [or Δ(δλ)(λλδ)] conformation in aqueous solution The authors’ calculations show that the interaction between the Ln^III ion and several donor atoms of the crown moiety is weakened as the ionic radius of the metal ion decreases, in line with the decrease of complex stability observed on proceeding to the right across the lanthanide series.

Dalton Transactions published new progress about 1128304-86-8. 1128304-86-8 belongs to pyridine-derivatives, auxiliary class Pyridines, name is 6,6′-((1,4,10,13-Tetraoxa-7,16-diazacyclooctadecane-7,16-diyl)bis(methylene))dipicolinic acid, and the molecular formula is C26H36N4O8, Synthetic Route of 1128304-86-8.

Referemce:
https://en.wikipedia.org/wiki/Pyridine,
Pyridine | C5H5N – PubChem

Hu, Aohan published the artcileMacrocyclic Ligands with an Unprecedented Size-Selectivity Pattern for the Lanthanide Ions, COA of Formula: C26H36N4O8, the publication is Journal of the American Chemical Society (2020), 142(31), 13500-13506, database is CAplus and MEDLINE.

Lanthanides (Ln³⁺) are critical materials used for many important applications, often as coordination compounds Tuning the thermodn. stability of these compounds is a general concern, which is not readily achieved due to the similar coordination chem. of lanthanides. Herein, the authors report two 18-membered macrocyclic ligands called macrodipa and macrotripa that show for the first time a dual selectivity toward both the light, large Ln³⁺ ions and the heavy, small Ln³⁺ ions, as determined by potentiometric titrations The lanthanide complexes of these ligands were investigated by NMR spectroscopy and x-ray crystallog., which revealed the occurrence of a significant conformational toggle between a 10-coordinate Conformation A and an 8-coordinate Conformation B that accommodates Ln³⁺ ions of different sizes. The origin of this selectivity pattern was further supported by d. functional theory (DFT) calculations, which show the complementary effects of ligand strain energy and metal-ligand binding energy that contribute to this conformational switch. This work demonstrates how novel ligand design strategies can be applied to tune the selectivity pattern for the Ln³⁺ ions.

Journal of the American Chemical Society published new progress about 1128304-86-8. 1128304-86-8 belongs to pyridine-derivatives, auxiliary class Pyridines, name is 6,6′-((1,4,10,13-Tetraoxa-7,16-diazacyclooctadecane-7,16-diyl)bis(methylene))dipicolinic acid, and the molecular formula is C26H36N4O8, COA of Formula: C26H36N4O8.

Referemce:
https://en.wikipedia.org/wiki/Pyridine,
Pyridine | C5H5N – PubChem

Thiele, Nikki A. published the artcileRapid Dissolution of BaSO₄ by Macropa, an 18-Membered Macrocycle with High Affinity for Ba²⁺, Related Products of pyridine-derivatives, the publication is Journal of the American Chemical Society (2018), 140(49), 17071-17078, database is CAplus and MEDLINE.

Insoluble BaSO₄ scale is a costly and time-consuming problem in the petroleum industry. Clearance of BaSO₄-impeded pipelines requires chelating agents that can efficiently bind Ba²⁺, the largest nonradioactive +2 metal ion. Due to the poor affinity of currently available chelating agents for Ba²⁺, however, the dissolution of BaSO₄ remains inefficient, requiring very basic solutions of ligands. In this study, we investigated three diaza-18-crown-6 macrocycles bearing different pendent arms for the chelation of Ba²⁺ and assessed their potential for dissolving BaSO₄ scale. Remarkably, the bis-picolinate ligand macropa exhibits the highest affinity reported to date for Ba²⁺ at pH 7.4 (log K’ = 10.74), forming a complex of significant kinetic stability with this large metal ion. Furthermore, the BaSO₄ dissolution properties of macropa dramatically surpass those of the state-of-the-art ligands DTPA and DOTA. Using macropa, complete dissolution of a molar equivalent of BaSO₄ is reached within 30 min at room temperature in pH 8 buffer, conditions under which DTPA and DOTA only achieve 40% dissolution of BaSO₄. When further applied for the dissolution of natural barite, macropa also outperforms DTPA, showing that this ligand is potentially valuable for industrial processes. Collectively, this work demonstrates that macropa is a highly effective chelator for Ba²⁺ that can be applied for the remediation of BaSO₄ scale.

Journal of the American Chemical Society published new progress about 1128304-86-8. 1128304-86-8 belongs to pyridine-derivatives, auxiliary class Pyridines, name is 6,6′-((1,4,10,13-Tetraoxa-7,16-diazacyclooctadecane-7,16-diyl)bis(methylene))dipicolinic acid, and the molecular formula is C10H15NO, Related Products of pyridine-derivatives.

Referemce:
https://en.wikipedia.org/wiki/Pyridine,
Pyridine | C5H5N – PubChem

Bell, Meghan M. published the artcileGlypican-3-targeted alpha particle therapy for hepatocellular carcinoma, Formula: C26H36N4O8, the publication is Molecules (2021), 26(1), 4, database is CAplus and MEDLINE.

Glypican-3 (GPC3) is expressed in 75% of hepatocellular carcinoma (HCC), but not normal liver, making it a promising HCC therapeutic target. GC33 is a full-length humanized monoclonal IgG1 specific to GPC3 that can localize to HCC in vivo. GC33 alone failed to demonstrate therapeutic efficacy when evaluated in patients with HCC; however, we posit that cytotoxic functionalization of the antibody with therapeutic radionuclides, may be warranted. Alpha particles, which are emitted by radioisotopes such as Actinium-225 (Ac-225) exhibit high linear energy transfer and short pathlength that, when targeted to tumors, can effectively kill cancer and limit bystander cytotoxicity. Macropa, an 18-member heterocyclic crown ether, can stably chelate Ac-225 at room temperature Here, we synthesized and evaluated the efficacy of [225Ac]Ac-Macropa-GC33 in mice engrafted with the GPC3-expressing human liver cancer cell line HepG2. Following a pilot dose-finding study, mice (n = 10 per group) were treated with (1) PBS, (2) mass-equivalent unmodified GC33, (3) 18.5 kBq [225Ac]Ac-Macropa-IgG1 (isotype control), (4) 9.25 kBq [225Ac]Ac-Macropa-GC33, and (5) 18.5 kBq [225Ac]Ac-Macropa-GC33. While significant toxicity was observed in all groups receiving radioconjugates, the 9.25 kBq [225Ac]Ac-Macropa-GC33 group demonstrated a modest survival advantage compared to PBS (p = 0.0012) and 18.5 kBq [225Ac]Ac-IgG1 (p = 0.0412). Hematol. anal. demonstrated a marked, rapid reduction in white blood cells in all radioconjugate-treated groups compared to the PBS and unmodified GC33 control groups. Our studies highlight a significant disadvantage of using directly-labeled biomols. with long blood circulation times for TAT. Strategies to mitigate such treatment toxicity include dose fractionation, pretargeting, and using smaller targeting ligands.

Molecules published new progress about 1128304-86-8. 1128304-86-8 belongs to pyridine-derivatives, auxiliary class Pyridines, name is 6,6′-((1,4,10,13-Tetraoxa-7,16-diazacyclooctadecane-7,16-diyl)bis(methylene))dipicolinic acid, and the molecular formula is C26H36N4O8, Formula: C26H36N4O8.

Referemce:
https://en.wikipedia.org/wiki/Pyridine,
Pyridine | C5H5N – PubChem

Shalgunov, Vladimir published the artcileRadiolabeling of a polypeptide polymer for intratumoral delivery of alpha-particle emitter, ²²⁵Ac, and beta-particle emitter, ¹⁷⁷Lu, Safety of 6,6′-((1,4,10,13-Tetraoxa-7,16-diazacyclooctadecane-7,16-diyl)bis(methylene))dipicolinic acid, the publication is Nuclear Medicine and Biology (2022), 11-21, database is CAplus and MEDLINE.

Radiotherapy of cancer requires both alpha- and beta-particle emitting radionuclides, as these radionuclide types are efficient at destroying different types of tumors. Both classes of radionuclides require a vehicle, such as an antibody or a polymer, to be delivered and retained within the tumor. Polyglutamic acid (pGlu) is a polymer that has proven itself effective as a basis of drug-polymer conjugates in the clinic, while its derivatives have been used for pretargeted tumor imaging in a research setup. trans-Cyclooctene (TCO) modified pGlu is suitable for pretargeted imaging or therapy, as well as for intratumoral radionuclide therapy. In all cases, it becomes indirectly radiolabeled via the bioorthogonal click reaction with the tetrazine (Tz) mol. carrying the radionuclide. In this study, we report the radiolabeling of TCO-modified pGlu with either lutetium-177 (¹⁷⁷Lu), a beta-particle emitter, or actinium-225 (²²⁵Ac), an alpha-particle emitter, using the click reaction between TCO and Tz. A panel of Tz derivatives containing a metal ion binding chelator (DOTA or macropa) connected to the Tz moiety directly or through a polyethylene glycol (PEG) linker was synthesized and tested for their ability to chelate ¹⁷⁷Lu and ²²⁵Ac, and click to pGlu-TCO. Radiolabeled ¹⁷⁷Lu-pGlu and ²²⁵Ac-pGlu were isolated by size exclusion chromatog. The retention of ¹⁷⁷Lu or ²²⁵Ac by the obtained conjugates was investigated in vitro in human serum. All DOTA-modified Tzs efficiently chelated ¹⁷⁷Lu resulting in average radiochem. conversions (RCC) of >75. Isolated radiochem. yields (RCY) for ¹⁷⁷Lu-pGlu prepared from ¹⁷⁷Lu-Tzs ranged from 31to 55. TLC analyses detected <5unchelated ¹⁷⁷Lu for all ¹⁷⁷Lu-pGlu preparations over six days in human serum. For ²²⁵Ac chelation, optimized RCCs ranged from 61 ± 34to quant. for DOTA-Tzs and were quant. for the macropa-modified Tz (>98). Isolated radiochem. yields (RCY) for ²²⁵Ac-pGlu prepared from ²²⁵Ac-Tzs ranged from 28to 51. For 3 out of 5 ²²⁵Ac-pGlu conjugates prepared from DOTA-Tzs, the amount of unchelated ²²⁵Ac stayed below 10over six days in human serum, while ²²⁵Ac-pGlu prepared from macropa-Tz showed a steady release of up to 37²²⁵Ac. We labeled TCO-modified pGlu polymers with alpha- and beta-emitting radionuclides in acceptable RCYs. All ¹⁷⁷Lu-pGlu preparations and some ²²⁵Ac-pGlu preparations showed excellent stability in human plasma. Our work shows the potential of pGlu as a vehicle for alpha- and beta-radiotherapy of tumors and demonstrated the usefulness of Tz ligation for indirect radiolabeling.

Nuclear Medicine and Biology published new progress about 1128304-86-8. 1128304-86-8 belongs to pyridine-derivatives, auxiliary class Pyridines, name is 6,6′-((1,4,10,13-Tetraoxa-7,16-diazacyclooctadecane-7,16-diyl)bis(methylene))dipicolinic acid, and the molecular formula is C18H12FN, Safety of 6,6′-((1,4,10,13-Tetraoxa-7,16-diazacyclooctadecane-7,16-diyl)bis(methylene))dipicolinic acid.

Referemce:
https://en.wikipedia.org/wiki/Pyridine,
Pyridine | C5H5N – PubChem

Ferreiros-Martinez, Raquel published the artcileMacrocyclic receptor showing extremely high Sr(II)/Ca(II) and Pb(II)/Ca(II) selectivities with potential application in chelation treatment of metal intoxication, Safety of 6,6′-((1,4,10,13-Tetraoxa-7,16-diazacyclooctadecane-7,16-diyl)bis(methylene))dipicolinic acid, the publication is Inorganic Chemistry (2011), 50(8), 3772-3784, database is CAplus and MEDLINE.

Herein the authors report a detailed study of the complexation properties of the macrocyclic decadentate receptor N,N’-Bis[(6-carboxy-2-pyridyl)methyl]-4,13-diaza-18-crown-6 (H₂bp18c6) toward different divalent metal ions [Zn(II), Cd(II), Pb(II), Sr(II), and Ca(II)] in aqueous solution This ligand is especially suited for the complexation of large metal ions such as Sr(II) and Pb(II), which results in very high Pb(II)/Ca(II) and Pb(II)/Zn(II) selectivities (in fact, higher than those found for ligands widely used for the treatment of lead poisoning such as EDTA), as well as in the highest Sr(II)/Ca(II) selectivity reported so far. These results were rationalized from the structure of the complexes. X-ray crystal diffraction, ¹H and ¹³C NMR spectroscopy, as well as theor. calculations at the d. functional theory (B3LYP) level were performed. The authors’ results indicate that for large metal ions such as Pb(II) and Sr(II) the most stable conformation is Δ(δλδ)(δλδ), while for Ca(II) the authors’ calculations predict the Δ(λδλ)(λδλ) form being the most stable one. The selectivity that bp18c6^2- shows for Sr(II) over Ca(II) can be attributed to a better fit between the large Sr(II) ions and the relatively large crown fragment of the ligand. The x-ray crystal structure of the Pb(II) complex shows that the Δ(δλδ)(δλδ) conformation observed in solution is also maintained in the solid state. The Pb(II) ion is endocyclically coordinated, being directly bound to the 10 donor atoms of the ligand. The bond distances to the donor atoms of the pendant arms (2.55-2.60 Å) are substantially shorter than those between the metal ion and the donor atoms of the crown moiety (2.92-3.04 Å). This is a typical situation observed for the so-called hemidirected compounds, in which the Pb(II) lone pair is stereochem. active. The x-ray structures of the Zn(II) and Cd(II) complexes show that these metal ions are exocyclically coordinated by the ligand, which explains the high Pb(II)/Cd(II) and Pb(II)/Zn(II) selectivities. The authors’ receptor bp18c6^2- shows promise for application in chelation treatment of metal intoxication by Pb(II) and ⁹⁰Sr(II).

Inorganic Chemistry published new progress about 1128304-86-8. 1128304-86-8 belongs to pyridine-derivatives, auxiliary class Pyridines, name is 6,6′-((1,4,10,13-Tetraoxa-7,16-diazacyclooctadecane-7,16-diyl)bis(methylene))dipicolinic acid, and the molecular formula is C26H36N4O8, Safety of 6,6′-((1,4,10,13-Tetraoxa-7,16-diazacyclooctadecane-7,16-diyl)bis(methylene))dipicolinic acid.

Referemce:
https://en.wikipedia.org/wiki/Pyridine,
Pyridine | C5H5N – PubChem

Regueiro-Figueroa, Martin published the artcileUnderstanding Stability Trends along the Lanthanide Series, Application of 6,6′-((1,4,10,13-Tetraoxa-7,16-diazacyclooctadecane-7,16-diyl)bis(methylene))dipicolinic acid, the publication is Chemistry – A European Journal (2014), 20(14), 3974-3981, database is CAplus and MEDLINE.

The stability trends across the lanthanide series of complexes with the polyaminocarboxylate ligands TETA^4- (H₄TETA = 2,2′,2”,2”’-(1,4,8,11-tetraazacyclotetradecane-1,4,8,11-tetrayl)tetraacetic acid), BCAED^4- (H₄BCAED = 2,2′,2”,2”’-{[(1,4-diazepane-1,4-diyl)bis(ethane-2,1-diyl)]bis(azanetriyl)}tetraacetic acid), and BP18C6^2- (H₂BP18C6 = 6,6′-[(1,4,10,13-tetraoxa-7,16-diazacyclooctadecane-7,16-diyl)bis(methylene)]dipicolinic acid) were investigated using DFT calculations Geometry optimizations performed at the TPSSh/6-31G(d,p) level, and using a 46 + 4fⁿ ECP for lanthanides, provide bond lengths of the metal coordination environments in good agreement with the exptl. values observed in the X-ray structures. The contractions of the Ln³⁺ coordination spheres follow quadratic trends, as observed previously for different isostructural series of complexes. We show here that the parameters obtained from the quant. anal. of these data can be used to rationalize the observed stability trends across the 4f period. The stability trends along the lanthanide series were also evaluated by calculating the free energy for the reaction [La(L)]^n+/-_(sol) + Ln³⁺_(sol)→[Ln(L)]^n+/-_(sol) + La³⁺_(sol). A parameterization of the Ln³⁺ radii was performed by minimizing the differences between exptl. and calculated standard hydration free energies. The calculated stability trends are in good agreement with the exptl. stability constants, which increase markedly across the series for BCAED^4- complexes, increase smoothly for the TETA^4- analogs, and decrease in the case of BP18C6^2- complexes. The resulting stability trend is the result of a subtle balance between the increased binding energies of the ligand across the lanthanide series, which contribute to an increasing complex stability, and the increase in the absolute values of hydration energies along the 4f period.

Chemistry – A European Journal published new progress about 1128304-86-8. 1128304-86-8 belongs to pyridine-derivatives, auxiliary class Pyridines, name is 6,6′-((1,4,10,13-Tetraoxa-7,16-diazacyclooctadecane-7,16-diyl)bis(methylene))dipicolinic acid, and the molecular formula is C26H36N4O8, Application of 6,6′-((1,4,10,13-Tetraoxa-7,16-diazacyclooctadecane-7,16-diyl)bis(methylene))dipicolinic acid.

Referemce:
https://en.wikipedia.org/wiki/Pyridine,
Pyridine | C5H5N – PubChem

Jensen, Mark P. published the artcileAqueous Complexes for Efficient Size-based Separation of Americium from Curium, Formula: C26H36N4O8, the publication is Inorganic Chemistry (2014), 53(12), 6003-6012, database is CAplus and MEDLINE.

Complexation of the adjacent actinide ions americium(III) and curium(III) by the ligand N,N’-bis[(6-carboxy-2-pyridyl)methyl]-1,10-diaza-18-crown-6 (H₂bp18c6) in aqueous solution was studied to quantify and characterize its americium/curium selectivity. Liquid-liquid extraction and spectrophotometric titration indicated the presence of both fully deprotonated and monoprotonated complexes, An(bp18c6)⁺ and An(Hbp18c6)²⁺ (An = Am or Cm), at the acidities that would be encountered when treating nuclear wastes. The stability constants of the complexes in 1 M NaNO₃ determined using competitive complexation were log β₁₀₁ = 15.49 ± 0.06 for Am and 14.88 ± 0.03 for Cm, indicating a reversal of the usual order of complex stability, where ligands bind the smaller Cm^III ion more tightly than Am^III. The Am/Cm selectivity of bp18c6^2- that is defined by the ratio of the Am and Cm stability constants (β₁₀₁ Am/β₁₀₁ Cm = 4.1) is the largest reported so far for binary An^III-ligand complexes. Theor. d. functional theory calculations using the B3LYP functional suggest that the ligand’s size-selectivity for larger 4f- and 5f-element cations arises from steric constraints in the crown ether ring. Enhanced 5f character in MOs involving actinide-nitrogen interactions is predicted to favor actinide(III) complexation by bp18c6^2- over the complexation of similarly sized lanthanide(III) cations.

Inorganic Chemistry published new progress about 1128304-86-8. 1128304-86-8 belongs to pyridine-derivatives, auxiliary class Pyridines, name is 6,6′-((1,4,10,13-Tetraoxa-7,16-diazacyclooctadecane-7,16-diyl)bis(methylene))dipicolinic acid, and the molecular formula is C26H36N4O8, Formula: C26H36N4O8.

Referemce:
https://en.wikipedia.org/wiki/Pyridine,
Pyridine | C5H5N – PubChem

Jensen, Mark P. published the artcileSolvent Extraction Separation of Trivalent Americium from Curium and the Lanthanides, Recommanded Product: 6,6′-((1,4,10,13-Tetraoxa-7,16-diazacyclooctadecane-7,16-diyl)bis(methylene))dipicolinic acid, the publication is Solvent Extraction and Ion Exchange (2015), 33(4), 329-345, database is CAplus.

The sterically constrained, macrocyclic, aqueous soluble ligand N,N’-bis[(6-carboxy-2-pyridyl)methyl]-1,10-diaza-18-crown-6 (H₂BP18C6) was investigated for separating americium from curium and all the lanthanides by solvent extraction Pairing H₂BP18C6, which favors complexation of larger f-element cations, with acidic organophosphorus extractants that favor extraction of smaller f-element cations, such as bis-(2-ethylhexyl)phosphoric acid (HDEHP) or (2-ethylhexyl)phosphonic acid mono(2-ethylhexyl) ester (HEH[EHP]), created solvent extraction systems with good Cm/Am selectivity, excellent trans-lanthanide selectivity (K_ex,Lu/K_ex,La = 10⁸), but poor selectivity for Am against the lightest lanthanides. However, using an organic phase containing both a neutral extractant, N,N,N’,N’-tetra(2-ethylhexyl)diglycolamide (TEHDGA), and HEH[EHP] enabled rejection of the lightest lanthanides during loading of the organic phase from aqueous nitric acid, eliminating their interference in the americium stripping stages. In addition, although it is a macrocyclic ligand, H₂BP18C6 does not significantly impede the mass transfer kinetics of the HDEHP solvent extraction system.

Solvent Extraction and Ion Exchange published new progress about 1128304-86-8. 1128304-86-8 belongs to pyridine-derivatives, auxiliary class Pyridines, name is 6,6′-((1,4,10,13-Tetraoxa-7,16-diazacyclooctadecane-7,16-diyl)bis(methylene))dipicolinic acid, and the molecular formula is C26H36N4O8, Recommanded Product: 6,6′-((1,4,10,13-Tetraoxa-7,16-diazacyclooctadecane-7,16-diyl)bis(methylene))dipicolinic acid.

Referemce:
https://en.wikipedia.org/wiki/Pyridine,
Pyridine | C5H5N – PubChem