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Dive into the research topics where Leonor Maria is active.

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Featured researches published by Leonor Maria.


Dalton Transactions | 2009

Tris(pyrazolyl)methane 99mTc tricarbonyl complexes for myocardial imaging

Leonor Maria; Célia Fernandes; Raquel Garcia; Lurdes Gano; António Paulo; Isabel Santos

Novel ether-containing tris(pyrazolyl)methane chelators stabilize thefac-[99mTc(CO)3]+ moiety providing complexes with significant, fast and stable heart uptake, together with a extremely fast liver clearance.


Dalton Transactions | 2007

Rhenium and technetium tricarbonyl complexes anchored by pyrazole-based tripods: novel lead structures for the design of myocardial imaging agents

Leonor Maria; Susana Cunha; Margarida Videira; Lurdes Gano; António Paulo; Isabel Santos

This report describes the synthesis and biological evaluation of cationic (99m)Tc-tricarbonyl complexes anchored by ether-containing tris(pyrazolyl)methane or bis(pyrazolyl)ethanamine ligands to be applied in the design of radiopharmaceuticals for myocardial imaging: fac-[(99m)Tc(CO)(3){RC(pz)(3)}](+) (R = H (1a), MeOCH(2) (2a), EtOCH(2) (3a), (n)PrOCH(2) (4a)) and fac-[(99m)Tc(CO)(3){RNHCH(2)CH(pz)(2)}](+) (R = H (5a), MeO(CH(2))(2) (6a)) (pz = pyrazolyl). At the no carrier added level, complexes 1a-6a were obtained in high radiochemical yield (> 98%) by reaction of fac-[(99m)Tc(CO)(3)(H(2)O)(3)](+) with the corresponding tripod chelator in aqueous medium. All these complexes display a high in vitro and in vivo stability, except 6a which metabolizes in vivo yielding fac-[(99m)Tc(CO)(3){HO(CH(2))(2)NHCH(2)CH(pz)(2)}](+) (7a). Biological studies in mice have shown that among the radiotracers evaluated in this work, 3a, anchored by a tris(pyrazolyl)methane chelator bearing an ethyl methyl ether substituent, has the highest heart uptake (3.6 +/- 0.5%ID g(-1) at 60 min p.i.). Complex 3a presents also the best heart: blood, heart: liver and heart: lung ratios, appearing as the most promising as a potential myocardial imaging agent. The chemical identity of 1a-7a was ascertained by HPLC comparison with the previously reported fac-[Re(CO)(3){HC(pz)(3)}]Br (1) and with the novel fac-[Re(CO)(3){RC(pz)(3)}]Br (R = MeOCH(2) (2), EtOCH(2) (3), (n)PrOCH(2)(4)) and fac-[Re(CO)(3){RNHCH(2)CH(pz)(2)}]Br (R = H (5), MeO(CH(2))(2) (6) HO(CH(2))(2) (7)). The novel Re(I) tricarbonyl complexes, 2-7, were characterized by the common analytical techniques, including single crystal X-ray diffraction analysis. The solid state structure confirmed the presence of facial and tridentate (kappa(3)-N(3)) anchor ligands. Solution NMR studies have also shown that this kappa(3)-N(3) coordination mode is retained in solution for all complexes (2-7).


Journal of Organometallic Chemistry | 2001

Iodo bis bistrimethylsilylamido lanthanides

Jacqueline Collin; Nicolas Giuseppone; Nada Jaber; Angela Domingos; Leonor Maria; Isabel Santos

Abstract Reactions of lanthanide triiodides with potassium bistrimethylsilyl amide have been investigated. For lanthanum, recrystallisation from THF–toluene led to monocrystals of the dimeric bisamide [La(μ-I){N(TMS) 2 } 2 (THF)] 2 . We have shown that samarium diiodide and lanthanide triiodides are efficient for lanthanum and samarium reactions, a mixture of tris amides and iodo bisamides is obtained, while only the latter compound is obtained for ytterbium.


Inorganic Chemistry | 2015

Uranium(III) redox chemistry assisted by a hemilabile bis(phenolate) cyclam ligand: uranium-nitrogen multiple bond formation comprising a trans-{RN═U(VI)═NR}(2+) complex.

Leonor Maria; Isabel Santos; Vânia R. Sousa; Joaquim Marçalo

A new monoiodide U(III) complex anchored on a hexadentate dianionic 1,4,8,11-tetraazacyclotetradecane-based bis(phenolate) ligand, [U(κ(6)-{((tBu2)ArO)2Me2-cyclam})I] (1), was synthesized from the reaction of [UI3(THF)4] (THF = tetrahydrofuran) and the respective potassium salt K2((tBu2)ArO)2Me2-cyclam and structurally characterized. Reactivity of 1 toward one-, two-, and four-electron oxidants was studied to explore the reductive chemistry of this new U(III) complex. Complex 1 reacts with one-electron oxidizers, such as iodine and TlBPh4, to form the seven-coordinate cationic uranium(IV) complexes [U(κ(6)-{((tBu2)ArO)2Me2-cyclam})I][X] (X = I (2-I), BPh4 (2-BPh4)). The new uranium(III) complex reacts with inorganic azides to yield the pseudohalide uranium(IV) complex [U(κ(6)-{((tBu2)ArO)2Me2-cyclam})(N3)2] (4) and the nitride-bridged diuranium(IV/IV) complex [(κ(4)-{((tBu2)ArO)2Me2-cyclam})(N3)U(μ-N)U(κ(5)-{((tBu2)ArO)2Me2-cyclam})] (5). Two equivalents of [U(κ(6)-{((tBu2)ArO)2Me2-cyclam})I] (1) effect the four-electron reduction of 1 equiv of PhN═NPh to form the bis(imido) complex [U(κ(4)-{((tBu2)ArO)2Me2-cyclam})(NPh)2] (6) and the U(IV) species 2-I. Moreover, the hemilability of the hexadentate ancillary ligand ((tBu2)ArO)2Me2-cyclam(2-) allows to perform the reductive cleavage of azobenzene with an unprecedented formation of a trans-bis(imido) complex. The complexes were characterized by NMR spectroscopy, and all the new uranium complexes were structurally authenticated by single-crystal X-ray diffraction.


Dalton Transactions | 2006

Rhenium(V) oxocomplexes with novel pyrazolyl-based N4- and N3S-donor chelators

Carolina Moura; Rute F. Vitor; Leonor Maria; António Paulo; Isabel Santos

The novel pyrazolyl-based ligands 3,5-Me2pz(CH2)2NH(CH2)2NH(CH2)2NH2 and pz*(CH2)2NH-Gly-CH2STrit (pz*=pz, 3,5-Me2pz, 4-(EtOOC)CH(2)-3,5-Me2pz) were synthesized, and their suitability to stabilize Re(V) oxocomplexes was evaluated using different starting materials, namely (NBu4)[ReOCl4], [ReOCl3(PPh3)2] and trans-[ReO2(py)4]Cl. Compound reacts with trans-[ReO2(py)4]Cl yielding the cationic compound [ReO(OMe){3,5-Me2pz(CH2)2N(CH2)2NH(CH2)2NH2}](BPh4) in a low isolated yield. In contrast, the neutral complexes [ReO{pz*(CH2)2NH-Gly-CH2S}] (pz*=pz, 3,5-Me2pz, 4-(EtOOCCH2)-3,5-Me2pz) were synthesized almost quantitatively by reacting [ReOCl3(PPh3)2] or (NBu4)[ReOCl4] with the trityl-protected chelators. The X-ray diffraction analysis of and confirmed the tetradentate coordination mode of the respective ancillary ligands. In the monoanionic chelator coordinates to the metal through four nitrogen atoms, while in the chelator is trianionic, coordinating to the metal through three nitrogens and one sulfur atom. Solution NMR studies of , including two-dimensional NMR techniques (1H COSY and 1H/13C HSQC), confirmed that the N3S coordination mode of the chelators is retained in solution. Unlike , complexes may be considered relevant in the development of radiopharmaceuticals, as further corroborated by the synthesis of the congener [99mTcO{pz(CH2)2-NH-Gly-CH2S}]. This radioactive compound was obtained from 99mTcO4- in aqueous medium, in almost quantitative yield and with high specific activity and radiochemical purity.


Journal of Molecular Catalysis A-chemical | 2000

Uranium iodides as catalysts for Diels–Alder reactions

Jacqueline Collin; Leonor Maria; Isabel Santos

Abstract Uranium triiodide is found to be an efficient Lewis acid catalyst for various Diels–Alder reactions which are performed in mild conditions and with low amounts of catalysts. The replacement of an iodide by a dihydrobis(pyrazolyl)borate ligand does not increase activity or selectivity.


Inorganic Chemistry Communications | 2003

Synthesis, structure and solution behaviour of U(III) poly(3,5-diisopropylpyrazoly)borate complexes

Leonor Maria; Ângela Domingos; Isabel Santos

Abstract The novel KBp i Pr2 and the previously described KTp i Pr2 react with [UI3(THF)4], in THF, yielding the new compounds [ U { κ 3 -Bp i Pr2 )} 3 ] (1) and [ UI 2 ( κ 3 -Tp i Pr2 )( THF ) x ] (x=2–3) (2), respectively. Compound 1 is remarkably stable, while 2 decomposes in solution, being the main decomposition product [ UI 2 ( κ 3 -Tp i Pr2 )( κ 1 -pz i Pr2 H ) ] (3). The formation of 3 is prevented when [UI3(THF)4] reacts with KTp i Pr2 in toluene, in the presence of strong neutral coordinating ligands.


Journal of Biological Inorganic Chemistry | 2007

A new bisphosphonate-containing 99m Tc(I) tricarbonyl complex potentially useful as bone-seeking agent: synthesis and biological evaluation

Elisa Palma; Bruno L. Oliveira; João D. G. Correia; Lurdes Gano; Leonor Maria; Isabel Santos


Journal of Organometallic Chemistry | 2006

Synthesis and structural studies of rhenium(I) tricarbonyl complexes with thione containing chelators

Leonor Maria; Carolina Moura; António Paulo; Isabel Santos


Journal of the American Chemical Society | 2006

Very Small and Soft Scorpionates: Water Stable Technetium Tricarbonyl Complexes Combining a Bis-agostic (k3-H, H, S) Binding Motif with Pendant and Integrated Bioactive Molecules

Leonor Maria; António Paulo; Isabel Santos; Philipp Kurz; Bernhard Spingler; Roger Alberto

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Isabel Santos

Instituto Superior Técnico

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António Paulo

Instituto Superior Técnico

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Joaquim Marçalo

Instituto Superior Técnico

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Lurdes Gano

Instituto Superior Técnico

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Vânia R. Sousa

Instituto Superior Técnico

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Adelaide Cruz

Instituto Superior Técnico

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Angela Domingos

University College London

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Carolina Moura

Instituto Superior Técnico

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Célia Fernandes

Instituto Superior Técnico

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