Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 14 de 14
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Inorg Chem ; 59(3): 2030-2036, 2020 Feb 03.
Artigo em Inglês | MEDLINE | ID: mdl-31971379

RESUMO

The octadentate hydroxypyridinone chelator 3,4,3-LI(1,2-HOPO) is a promising therapeutic agent because of its high affinity for f-block elements and noncytotoxicity at medical dosages. The interaction between 3,4,3-LI(1,2-HOPO) and other biomedically relevant metals such as gold, however, has not been explored. Gold nanoparticles functionalized with chelators have demonstrated great potential in theranostics, yet thus far, no protocol that combines 3,4,3-LI(1,2-HOPO) and colloidal gold has been developed. Here, we characterize the solution thermodynamic properties of the complexes formed between 3,4,3-LI(1,2-HOPO) and Au3+ ions and demonstrate how under specific pH conditions the chelator promotes the growth of gold nanoparticles, acting as both reducing and stabilizing agent. 3,4,3-LI(1,2-HOPO) ligands on the nanoparticle surface remain active and selective toward f-block elements, as evidenced by gold nanoparticle selective aggregation. Finally, a new colorimetric assay capable of reaching the detection levels necessary for the quantification of lanthanides in waste from industrial processes is developed based on the inhibition of particle growth by lanthanides.

2.
Chemistry ; 26(11): 2354-2359, 2020 Feb 21.
Artigo em Inglês | MEDLINE | ID: mdl-31914232

RESUMO

Octadentate hydroxypyridinone (HOPO) and catecholamide (CAM) siderophore analogues are known to be efficacious chelators of the actinide cations, and these ligands are also capable of facilitating both activation and reduction of actinyl species. Utilizing X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) spectroscopies, as well as cyclic voltammetry measurements, herein, we elucidate chelation-based mechanisms for driving reactivity and initiating redox processes in a family of neptunyl-HOPO and CAM complexes. Based on the selected chelator, the ability to control the oxidation state of neptunium and the speed of reduction and concurrent oxo group activation was demonstrated. Most notably, reduction kinetics for the NpV O2 +/ /NpIV redox couple upon chelation by the ligands 3,4,3-LI(1,2-HOPO) and 3,4,3-LI(CAM)2 (1,2-HOPO)2 was observed to be faster than ever reported, and in fact quicker than we could measure using either X-ray absorption spectroscopy or electrochemical techniques.

3.
Chem Sci ; 10(28): 6834-6843, 2019 Jul 28.
Artigo em Inglês | MEDLINE | ID: mdl-31391906

RESUMO

Current methods for metal chelation are generally based on multidentate organic ligands, which are generated through cumbersome multistep synthetic processes that lack flexibility for systematically varying metal-binding motifs. Octadentate ligands incorporating hydroxypyridinone or catecholamide binding moieties onto a spermine scaffold are known to display some of the highest affinities towards f-elements. Enhancing binding affinity for specific lanthanide or actinide ions however, necessitates ligand architectures that allow for modular and high throughput synthesis. Here we introduce a high-throughput combinatorial library of 16 tetrameric N-substituted glycine oligomers (peptoids) containing hydroxypyridinone or catecholamide chelating units linked via an ethylenediamine bridge and, for comparison, we also synthesized the corresponding mixed ligands derived from the spermine scaffold: 3,4,3-LI(1,2-HOPO)2(CAM)2 and 3,4,3-LI(CAM)2(1,2-HOPO)2. Coordination-based luminescence studies were carried out with Eu3+ and Tb3+ to begin probing the properties of the new ligand architecture and revealed higher sensitization efficiency with the spermine scaffold as well as different spectroscopic features among the structural peptoid isomers. Solution thermodynamic properties of selected ligands revealed different coordination properties between the spermine and peptoid analogues with Eu3+ stability constants log ß 110 ranging from 28.88 ± 3.45 to 43.97 ± 0.49. The general synthetic strategy presented here paves the way for precision design of new specific and versatile ligands, with a variety of applications tailored towards the use of f-elements, including separations, optical device optimization, and pharmaceutical development.

4.
Chemistry ; 25(29): 7114-7118, 2019 May 23.
Artigo em Inglês | MEDLINE | ID: mdl-30970154

RESUMO

A new thorium metal-organic framework (MOF), Th(OBA)2 , where OBA is 4,4'-oxybis(benzoic) acid, has been synthesized hydrothermally in the presence of a range of nitrogen-donor coordination modulators. This Th-MOF, described herein as GWMOF-13, has been characterized by single-crystal and powder X-ray diffraction, as well as through a range of techniques including gas sorption, thermogravimetric analysis (TGA), solid-state UV/Vis and luminescence spectroscopy. Single-crystal X-ray diffraction analysis of GWMOF-13 reveals an interesting, high symmetry (cubic Ia 3 ‾ d) structure, which yields a novel srs-a topology. Most notably, TGA analysis of GWMOF-13 reveals framework stability to 525 °C, matching the thermal stability benchmarks of the UiO-66 series MOFs and zeolitic imidazolate frameworks (ZIFs), and setting a new standard for thermal stability in f-block based MOFs.

5.
Inorg Chem ; 57(22): 14337-14346, 2018 Nov 19.
Artigo em Inglês | MEDLINE | ID: mdl-30372069

RESUMO

The solution chemistry of a chelator developed for 227Th targeted alpha therapy was probed. The compound of interest is an octadentate ligand comprising four N-methyl-3-hydroxy-pyridine-2-one metal-binding units, two tertiary amine groups, and one carboxylate arm appended for bioconjugation. The seven p Ka values of the ligand and the stability constants of complexes formed with Th(IV), Hf(IV), Zr(IV), Gd(III), Eu(III), Al(III), and Fe(III) were determined. The ligand exhibits extreme thermodynamic selectivity toward tetravalent metal ions with a ca. 20 orders of magnitude difference between the formation constant of the Th(IV) species formed at physiological pH, namely [ThL]-, and that of its Eu(III) analogue. Likewise, log ß110 values of 41.7 ± 0.3 and 26.9 ± 0.3 (T = 25 °C) were measured for [ThL]- and [FeIIIL]2-, respectively, highlighting the high affinity and selectivity of the ligand for Th ions over potentially competing endogenous metals. Single crystal X-ray analysis of the Fe(III) complex revealed a dinuclear 2:2 metal:chelator complex crystallizing in the space group P1̅. The formation of this dimeric species is likely favored by several intramolecular hydrogen bonds and the protonation state of the chelator in acidic media. LIII edge EXAFS data on the Th(IV) complexes of both the ligand and a monoclonal antibody conjugate revealed the expected mononuclear 1:1 metal:chelator coordination environment. This was also confirmed by high resolution mass spectrometry. Finally, kinetic experiments demonstrated that labeling the bioconjugated ligand with Th(IV) could be achieved and completed after 1 h at room temperature, reinforcing the high suitability of this chelator for 227Th targeted alpha therapy.


Assuntos
Quelantes/química , Complexos de Coordenação/química , Piridonas/química , Compostos Radiofarmacêuticos/química , Tório/química , Anticorpos Monoclonais Humanizados/química , Cinética , Ligantes , Estrutura Molecular , Termodinâmica , Espectroscopia por Absorção de Raios X
6.
Chem Commun (Camb) ; 54(76): 10698-10701, 2018 Sep 20.
Artigo em Inglês | MEDLINE | ID: mdl-30187044

RESUMO

Oxo group activation with reduction of neptunyl(vi) and plutonyl(vi) to tetravalent hydroxo species by the hydroxypyridinone siderophore derivative 3,4,3-LI-(1,2-HOPO) was investigated in the gas-phase via electrospray ionization mass spectrometry, in solution via Raman spectroscopy, and computationally via density functional theory. Dissociation of the gas-phase tetravalent complexes resulted in actinide-hydroxo bond cleavage.

7.
Chemistry ; 24(49): 12747-12756, 2018 Sep 03.
Artigo em Inglês | MEDLINE | ID: mdl-29758104

RESUMO

Hybrid materials bearing elements from the 5f block display a rich diversity of coordination geometries, connectivities, and assembly motifs. Exemplary in this regard have been uranyl coordination polymers, which feature a wide range of secondary building units resulting from hydrolysis and oligomerization of the [UO2 ]2+ cation. An alternative approach to novel materials, however, suppresses hydrolysis and relies on non-covalent interactions (e.g. hydrogen or halogen bonding) to direct assembly of a more limited suite of species or building units. This may be achieved through the use of high-anion media to promote singular actinyl anions that are assembled with organic cations, or by way of functionalized chelating ligands that produce complexes suited for assembly through peripheral donor/acceptor sites. Presented in this Concept article is therefore an overview of our efforts in this arena. We highlight examples of each approach, share our thoughts regarding delineation of assembly criteria, and discuss the opportunities for exploring structure-property relationships in these systems.

8.
Inorg Chem ; 57(5): 2714-2723, 2018 Mar 05.
Artigo em Inglês | MEDLINE | ID: mdl-29436823

RESUMO

Bending the linear uranyl (UO22+) cation represents both a significant challenge and opportunity within the field of actinide hybrid materials. As part of related efforts to engage the nominally terminal oxo atoms of uranyl cation in noncovalent interactions, we synthesized a new uranyl complex, [UO2(C12H8N2)2(C7H2Cl3O2)2]·2H2O (complex 2), that featured both deviations from equatorial planarity and uranyl linearity from simple hydrothermal conditions. Based on this complex, we developed an approach to probe the nature and origin of uranyl bending within a family of hybrid materials, which was done via the synthesis of complexes 1-3 that display significant deviations from equatorial planarity and uranyl linearity (O-U-O bond angles between 162° and 164°) featuring 2,4,6-trihalobenzoic acid ligands (where Hal = F, Cl, and Br) and 1,10-phenanthroline, along with nine additional "nonbent" hybrid materials that either coformed with the "bent" complexes (4-6) or were prepared as part of complementary efforts to understand the mechanism(s) of uranyl bending (7-12). Complexes were characterized via single crystal X-ray diffraction and Raman, infrared (IR), and luminescence spectroscopy, as well as via quantum chemical calculations and density-based quantum theory of atoms in molecules (QTAIM) analysis. Looking comprehensively, these results are compared with the small library of bent uranyl complexes in the literature, and herein we computationally demonstrate the origin of uranyl bending and delineate the energetics behind this process.

9.
Chemistry ; 23(61): 15355-15369, 2017 Nov 02.
Artigo em Inglês | MEDLINE | ID: mdl-28707416

RESUMO

Engaging the nominally terminal oxo atoms of the linear uranyl (UO22+ ) cation in non-covalent interactions represents both a significant challenge and opportunity within the field of actinide hybrid materials. An approach has been developed for promoting oxo atom participation in a range of non-covalent interactions, through judicious choice of electron donating equatorial ligands and appropriately polarizable halogen-donor atoms. As such, a family of uranyl hybrid materials was generated based on a combination of 2,5-dihalobenzoic acid and aromatic, chelating N-donor ligands. Delineation of criteria for oxo participation in halogen bonding interactions has been achieved by preparing materials containing 2,5-dichloro- (25diClBA) and 2,5-dibromobenzoic acid (25diBrBA) coupled with 2,2'-bipyridine (bipy) (1 and 2), 1,10-phenanthroline (phen) (3-5), 2,2':6',2''-terpyridine (terpy) (6-8), or 4'-chloro-2,2':6',2''-terpyridine (Cl-terpy) (9-10), which have been characterized through single crystal X-ray diffraction, Raman, Infrared (IR), and luminescence spectroscopy, as well as through density functional calculations of electrostatic potentials. Looking comprehensively, these results are compared with recently published analogues featuring 2,5-diiodobenzoic acid which indicate that although inclusion of a capping ligand in the uranyl first coordination sphere is important, it is the polarizability of the selected halogen atom that ultimately drives halogen bonding interactions with the uranyl oxo atoms.

10.
Inorg Chem ; 56(15): 9156-9168, 2017 Aug 07.
Artigo em Inglês | MEDLINE | ID: mdl-28742345

RESUMO

The syntheses and crystal structures of six new heterometallic compounds containing the UO22+ cation, o-, m-, and p-iodobenzoic acid ligands, and Tl+, Rb+, and Cs+ cations which adopt the role of both charge balancing cation and secondary metal center are described, as are the luminescent properties for Tl+ containing compounds 1, 4, and 6. The structures of compounds 1-3 are isomorphous and contain uranyl monomers bound by o-iodobenzoic acid ligands with Tl+, Rb+, and Cs+ cations acting as secondary metal centers. Compounds 4 and 5 are also isomorphous and feature m-iodobenzoic acid ligands bound to the uranyl cation along with Tl+ and Rb+ cations. Compound 6 is unique in this series as it is assembled from a dimeric uranyl unit and features p-iodobenzoic acid ligands and Tl+ cations which function as charge balancing secondary metal centers. Single crystal X-ray diffraction analysis of these materials suggests that the secondary metal cations are incorporated based on the size of their ionic radius (Tl+ < Rb+ < Cs+), which is directly related to the size of the "pocket" observed in 1-6. Further, Voronoi-Dirichlet tessellation and Hirshfeld surface analysis were used to probe the coordination environment of the secondary metal centers as part of ongoing efforts to develop metrics for determining the coordination number of secondary metal cations in similar systems.

11.
Acta Crystallogr B Struct Sci Cryst Eng Mater ; 73(Pt 2): 234-239, 2017 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-28362287

RESUMO

The synthesis and crystal structure of a new uranyl coordination polymer featuring 3-bromo-5-iodobenzoic acid is described and the luminescent and vibrational properties of the material have been explored. Compound (1), [UO2(C7H3BrIO2)2]n, features dimeric uranyl units chelated and then linked by 3-bromo-5-iodobenzoic acid ligands to form a one-dimensional coordination polymer that is subsequently assembled via bifurcated halogen-bonding interactions with uranyl oxo atoms to form a supramolecular three-dimensional network. The asymmetric, bifurcated halogen-bonding interaction in (1) is notable as it represents the first observation of this synthon in a uranyl hybrid material. Raman and IR spectroscopy showed that halogen-bonding interactions with the uranyl oxo atoms result in small shifts in υ1 and υ3 frequencies, whereas luminescence spectra collected at an excitation wavelength of 420 nm reveal partially resolved uranyl emission.

12.
Inorg Chem ; 55(14): 6902-15, 2016 Jul 18.
Artigo em Inglês | MEDLINE | ID: mdl-27347607

RESUMO

The syntheses and crystal structures of 16 new rare-earth (RE = La(3+)-Y(3+))-3,5-dichlorobenzoic acid-terpyridine molecular materials characterized via single-crystal and powder X-ray diffraction are reported. These 16 complexes consist of four unique structure types ranging from molecular dimers (La(3+) and Ce(3+)) to tetramers (Pr(3+)-Y(3+)) as one moves across the RE(3+) series. This structural evolution is accompanied by subsequent changes in modes of supramolecular assembly (halogen bonding, halogen-π, halogen-halogen, and π-π interactions). Solid-state visible and near-infrared lifetime measurements were performed on complexes 6 (Sm(3+)), 7 (Eu(3+)), 9 (Tb(3+)), 10 (Dy(3+)), 11 (Ho(3+)), 12 (Er(3+)), and 14 (Yb(3+)), and characteristic emission was observed for all complexes except 11. Lifetime data for 11, 12, and 14 suggest sensitization by the terpy antenna does occur in near-infrared systems, although not as efficiently as in the visible region. Additionally, direct current magnetic susceptibility measurements were taken for complexes 10 (Dy(3+)) and 12 (Er(3+)) and showed dominant ferromagnetic behavior.

13.
Inorg Chem ; 55(6): 2682-4, 2016 Mar 21.
Artigo em Inglês | MEDLINE | ID: mdl-26923457

RESUMO

A cage cluster consisting of 31 uranyl and 9 Sm(3+) polyhedra self-assembles in an alkaline aqueous peroxide solution and crystallizes (U31Sm9). Trimers of Sm(3+) polyhedra are templated by µ3-η(2):η(2):η(2)-peroxide groups and link to oxo atoms of uranyl ions. Three such trimers link into a ring through uranyl hexagonal bipyramids, and these are attached through six polyhedra to a unit consisting of 21 uranyl hexagonal bipyramids to complete the cage. Luminescence spectra collected with an excitation wavelength of 420 nm reveal fine structure, which is not observed for a cluster containing only uranyl polyhedra.

14.
Dalton Trans ; 44(36): 15843-54, 2015 Sep 28.
Artigo em Inglês | MEDLINE | ID: mdl-26267388

RESUMO

Eleven new lanthanide (Ln = Nd-Lu)-thiophene-2,5-dicarboxylic acid (25-TDC)-2,2':6',2''-terpyridine (terpy) coordination polymers () which employ a dual ligand strategy have been synthesized hydrothermally and structurally characterized by single crystal and powder X-ray diffraction. Two additional members of the series ( and ) were made with Ce(3+) and Pr(3+) and characterized via powder X-ray diffraction only. The series is comprised of three similar structures wherein differences due to the lanthanide contraction manifest in Ln(3+) coordination number as well as the number of bound and solvent water molecules within the crystal lattice. Structure type I (Ce(3+)-Sm(3+)) contains two nine-coordinate Ln(3+) metal centers each with a bound water molecule. Structure type II (Eu(3+)-Ho(3+)) features a nine and an eight coordinate Ln(3+) metal along with one bound and one solvent water molecule. Structure type III (Er(3+)-Lu(3+)) includes two eight-coordinate Ln(3+) metal centers with both water molecules residing in the lattice. Assembly into supramolecular 3D networks via π-π interactions is observed for all three structure types, whereas structure types II and III also feature hydrogen-bonding interactions via the well-known C-HO and O-HO synthons. Visible and near-IR luminescence studies were performed on compounds , , , and at room temperature. As a result characteristic near-IR luminescent bands of Pr(3+), Nd(3+), Sm(3+), and Yb(3+) as well as visible bands of Sm(3+) were observed.


Assuntos
Ácidos Dicarboxílicos/química , Elementos da Série dos Lantanídeos/química , Compostos Organometálicos/síntese química , Polímeros/síntese química , Piridinas/química , Tiofenos/química , Ligantes , Modelos Moleculares , Compostos Organometálicos/química , Polímeros/química
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA