Rita Delgado

Bio: Rita Delgado is an academic researcher from Universidade Nova de Lisboa. The author has contributed to research in topics: Protonation & Metal ions in aqueous solution. The author has an hindex of 29, co-authored 144 publications receiving 3524 citations. Previous affiliations of Rita Delgado include Technical University of Lisbon & Instituto Superior Técnico.

Critical evaluation of stability constants of metal complexes of complexones for biomedical and environmental applications* (IUPAC Technical Report)

Abstract: Available experimental data on stability constants of proton (hydron) and metal complexes for seven complexones of particular biomedical and environmental interest: iminodiacetic acid (2,2'-azanediyldiacetic acid, IDA); (methyl-imino)diacetic acid (2,2'-(methylazanediyl)diacetic acid, MIDA); 2,2',2",2'''-{[(carboxymethyl)azanediyl]bis[(ethane-l,2-diyl)nitrilo]}tetraacetic acid (DTPA); 3.6,9,12-tetrakis(carboxymethyl )-3,6,9,12-tetraazatetradecanedioic acid (TTHA); 2,2',2"-(l,4,7-triazanonane-l,4,7-triyl)triacetic acid (NOTA); 2,2',2",2'''-(1,4,7,10-tetraazacyclododecane-1,4,7,10-tetrayl)tetraacetic acid (DOTA); 2,2',2",2'''-(1,4,8,11-tetraazacyclotetradecane-1,4,8,11-tetrayl)tetraacetic acid (TETA), published in 1945-2000, have been critically evaluated. Some typical errors in stability constant measurements for particular complexones are summarized. Higher quality data are selected and presented as "Recommended" or "Provisional".

Metal complexes of cyclen and cyclam derivatives useful for medical applications: a discussion based on thermodynamic stability constants and structural data

Abstract: A series of the most common chelators used in magnetic resonance imaging (MRI) and in radiopharmaceuticals for medical diagnosis and tumour therapy, H4dota, H4teta, H8dotp and H8tetp, is examined from a chemical point of view. Differences between 12- and 14-membered tetraazamacrocyclic derivatives with methylcarboxylate and methylphosphonate pendant arms and their chelates with divalent first-series transition metal and trivalent lanthanide ions are discussed on the basis of their thermodynamic stability constants, X-ray structures and theoretical studies.

Critical evaluation of stability constants and thermodynamic functions of metal complexes of crown ethers (IUPAC Technical Report)

Abstract: Stability constants and thermodynamic functions of metal complexes of crown ethers in various solvents published between 1971 and the beginning of 2000 have been critically evaluated. The most studied crown ethers have been selected: 1,4,7,10-tetraoxacyclododecane (12C4), 1,4,7,10,13-pentaoxacyclopentadecane (15C5), and 1,4,7,10,13,16-hexaoxacyclooctadecane (18C6). The metal ions chosen are: alkali and alkaline earth metal ions, Ag + , Tl + , Cd 2 + , and Pb 2 + . The solvents considered are: water, methanol, ethanol, and their mixtures, as well as acetonitrile, N,N'-dimethylformamide, dimethylsulfoxide, and propylene carbonate. The published data have been examined and grouped into two categories, "accepted" and "rejected". The "accepted" values were considered as: (i) recommended (R), when the standard deviations (s.d.) on the constant K or on Δ r H were ≤0.05 lg unit or ≤1 kJ mol - 1 , respectively; (ii) provisional (P), when 0.05 < s.d. ≤ 0.2 for lg K or 1 < s.d. ≤ 2 kJ mol - 1 for Δ r H; (iii) recommended 1 (R1), if the values were obtained by a single research group, but were considered reliable in comparison with related systems, and considering that the research team usually presents R-level values for other similar systems.

Stabilities of divalent and trivalent metal ion complexes of macrocyclic triazatriacetic acids

Abstract: Potentiomctric methods have been used to determine the stability constants of complexes of trivalent metal ions of Al 3+ , Fe 3+ , Ga 3+ , In 3+ , and Gd 3+ with the ligands 1-oxa-4,7,10-triazacyclododecane-N,N',N''-triacetic acid, 1, 1,7-dioxa-4,10,13-triazacyc1opentadecane-N,N',N''-triacetic acid, 2, and 1,7,13-trioxa-4,10,16-triazacyclooctadecaneN,N',N''-triacetic acid, 3, and of divalent metal ions of Co 2+ , Ni 2+ , Cu 2+ , Zn 2+ , Cd 2+ , and Pb 2+ with ligands 3

Gadolinium(III) Chelates as MRI Contrast Agents: Structure, Dynamics, and Applications

Abstract: A. Water Exchange 2326 B. Proton Exchange 2327 C. Electronic Relaxation 2327 D. Relaxivity 2331 E. Outerand Second-Sphere Relaxivity 2334 F. Methods of Improving Relaxivity 2336 V. Macromolecular Conjugates 2336 A. Introduction 2336 B. General Conjugation Methods 2336 C. Synthetic Linear Polymers 2336 D. Synthetic Dendrimer-Based Agents 2338 E. Naturally Occurring Polymers (Proteins, Polysaccharides, and Nucleic Acids) 2339

Anion receptor chemistry: highlights from 2007

Abstract: This critical review includes advances in anion complexation in the year 2007. The review covers anion receptors that employ amides and thioamides, pyrroles and indoles, ureas and thioureas, guanidinium, ammonium, and imidazolium groups and receptors containing hydroxyl groups. In addition, receptors containing metal ions or Lewis acids are discussed along with anion–π interactions and the membrane transport of anionic species by synthetic transporters and channels (204 references).

Coordinating Radiometals of Copper, Gallium, Indium, Yttrium and Zirconium for PET and SPECT Imaging of Disease

Abstract: Molecular imaging is the visualization, characterization and measurement of biological processes at the molecular and cellular levels in humans and other living systems. Molecular imaging agents are probes used to visualize, characterize and measure biological processes in living systems. These two definitions were put forth by the Sociey of Nuclear Medicine (SNM) in 2007 as a way to capture the interdisciplinary nature of this relatively new field. The emergence of molecular imaging as a scientific discipline is a result of advances in chemistry, biology, physics and engineering, and the application of imaging probes and technologies has reshaped the philosophy of drug discovery in the pharmaceutical sciences by providing more cost effective ways to evaluate the efficacy of a drug candidate and allowing pharmaceutical companies to reduce the time it takes to introduce new therapeutics to the marketplace. Finally the impact of molecular imaging on clinical medicine has been extensive since it allows a physician to diagnose a patient’s illness, prescribe treatment and monitor the efficacy of that treatment non-invasively. Single Photon Emission Computed Tomography (SPECT) and Positron Emission Tomography (PET) were the first molecular imaging modalities used clinically. SPECT requires the use of a contrast agent labeled with a gamma emitting radionuclide, which should have an ideal gamma energy of 100-250 keV. These gamma rays are recorded by the detectors of a dedicated gamma camera or SPECT instrument and after signal processing can be converted into an image indentifying the localization of the radiotracer. PET requires the injected radiopharmaceutical to be labeled with a positron emitting radionuclide. As the radionuclide decays it ejects a positron from its nucleus which travels a short distance before being annihilated with an electron to release two 511 keV gamma rays 180° apart that are detected by the PET scanner (Figure 1). After sufficient acquisition time the data are reconstructed using computer based algorithms to yield images of the radiotracer’s location within the organism. When compared to SPECT, PET has greater advantages with respect to sensitivity and resolution and has been gaining in clinical popularity, with the number of PET-based studies expected to reach 3.2 million by 2010.1 While SPECT and PET technology has been around for decades, its use remained limited because of the limited availability of relevant isotopes which had to be produced in nuclear reactors or particle accelerators. However, the introduction of the small biomedical cyclotron, the self-contained radionuclide generator and the dedicated small animal or clinical SPECT and PET scanners to hospitals and research facilities has increased the demand for SPECT and PET isotopes. Figure 1 Cartoon depicting the fundamental principle of Positron Emission Tomography (PET). As the targeting group interacts with the cell surface receptor, the positron emitting radio-metal decays by ejecting β+ particles from its nucleus. After traveling ... Traditional PET isotopes such as 18F, 15O, 13N and 11C have been developed for incorporation into small molecules, but due to their often lengthy radio-syntheses, short half-lives and rapid clearance, only early time points were available for imaging, leaving the investigation of biological processes, which occur over the duration of hours or days, difficult to explore. With the continuing development of biological targeting agents such as proteins, peptides, antibodies and nanoparticles, which demonstrate a range of biological half-lives, a need arose to produce new radionuclides with half-lives complementary with their biological properties. As a result, the production and radiochemistry of radiometals such as Zr, Y, In, Ga and Cu have been investigated as radionuclide labels for biomolecules since they have the potential to combine their favorable decay characteristics with the biological characteristics of the targeting molecule to become a useful radiopharmaceutical (Tables ​(Tables11 and ​and22).2 Table 1 Gamma- and Beta-Emitting Radiometals Table 2 Positron-Emitting Radiometals The number of papers published describing the production or use of these radiometals continues to expand rapidly, and in recognition of this fact, the authors have attempted to present a comprehensive review of this literature as it relates to the production, ligand development and radiopharmaceutical applications of radiometals (excluding 99mTc) since 1999. While numerous reviews have appeared describing certain aspects of the production, coordination chemistry or application of these radiometals,2-18 very few exhaustive reviews have been published.10,12 Additionally, this review has been written to be used as an individual resource or as a companion resource to the review written by Anderson and Welch in 1999.12 Together, they provide a literature survey spanning 50 years of scientific discovery. To accomplish this goal, this review has been organized into three sections: the first section discusses the coordination chemistry of the metal ions Zr, Y, In, Ga and Cu and their chelators in the context of radiopharmaceutical development; the second section describes the methods used to produce Zr, Y, In, Ga and Cu radioisotopes; and the final section describes the application of these radiometals in diagnostic imaging and radiotherapy.

Anion receptors based on organic frameworks: highlights from 2005 and 2006

Abstract: This critical review covers advances in anion complexation chemistry related to receptors based on organic frameworks in the years 2005–2006. The review covers anion receptors that employ amides and thioamides, pyrroles and indoles, ureas and thioureas, ammonium, guanidinium, imidazolium, and receptors containing hydroxyl groups. There is a discussion of anion templated assembly, followed by a short section outlining modelling studies of these systems. (226 references.)