Miguel Martínez-Calvo

• Dr
• Professor (Assistant) at University of Santiago de Compostela

The development of transition metal catalysts capable of promoting non-natural transformations within living cells can open significant new avenues in chemical and cell biology. Unfortunately, the complexity of the cell makes it extremely difficult to translate standard organometallic chemistry to living environments. Therefore, progress in this fi...

We describe an approach to regulate the cellular uptake of small gold nanoparticles using supramolecular chemistry. The strategy relies on the functionalization of AuNPs with negatively charged pyranines, which largely hamper their penetration in cells. Cellular uptake can be activated in situ through the addition of cationic covalent cages that sp...

Discrete palladium (II) complexes featuring purposely designed phosphine ligands can promote depropargylation and deallylation reactions in cell lysates. The performance of these complexes is superior to that of other palladium sources, which apparently are rapidly deactivated in such hostile complex media. This good balance between reactiv-ity and...

The site‐selective modification of biomolecules has grown spectacularly in recent years. The presence of a large number of functional groups in a biomolecule makes its chemo‐ and regioselective modification a challenging goal. In this context, transition‐metal‐mediated reactions are emerging as a powerful tool owing to their unique reactivity and g...

We show the first example of a bisthiosemicarbazone silver double-tetranuclear cluster helicate [Ag 4 L 2 ] 2 obtained by electrochemical synthesis which undergoes a rare desulfurization process giving rise to a cationic silver dihelicate [Ag 2 (H 2 L) 2 ]SO 4 .

Cluster helicates are a new type of supramolecular architectures that consist in a metal cluster wrapped around by ligands arranged in a helical mode. This class of compounds combines the...

Nesta práctica experimental, exploramos o fenómeno do “efecto salino” sobre diferentes disolucións, para tratar de comprender que son e como actúan as forzas intermoleculares. Realizaremos esta exploración mediante a observación da separación de fases no seguinte experimento: a unha disolución composta por auga e acetona, engádeselle sal de mesa (c...

The synthesis of a family of chiral and enantiomerically pure pyridyl‐diamide (pda) ligands that upon complexation with europium [Eu(CF3SO3)3] result in chiral complexes with metal centered luminescence is reported; the sets of enantiomers giving rise to both circular dichroism (CD) and circularly polarized luminescence (CPL) signatures. The solid‐...

Manganosalen complexes are a class of catalytic antioxidants with beneficial effects against different neurological disorders according to various in vitro and in vivo studies. The interest in the factors that determine their antioxidant activity is based on the fact that they are key to achieving more efficient models. In this work, we report a se...

Background Previous studies by our group have shown that oxidative phosphorylation (OXPHOS) is the main pathway by which pancreatic cancer stem cells (CSCs) meet their energetic requirements; therefore, OXPHOS represents an Achille’s heel of these highly tumorigenic cells. Unfortunately, therapies that target OXPHOS in CSCs are lacking. Methods Th...

Background and aims: Annual world-wide cancer-related fatalities remain high for pancreatic ductal adenocarcinoma (PDAC), largely due to the presence of “stem-like” tumor cells known as cancer stem cells (CSCs). Previous studies by our group have shown that oxidative phosphorylation (OXPHOS) is the main pathway by which pancreatic CSCs meet their e...

The study of the inherent factors that influence the isolation of one type of metallosupramolecular architecture over another is one of the main objectives in the field of Metallosupramolecular Chemistry. In this work, we report two new neutral copper(II) helicates, [Cu2(L1)2]·4CH3CN and [Cu2(L2)2]·CH3CN, obtained by means of an electrochemical met...

The study of the inherent factors that influence the isolation of one type of metallosupramolecular architecture over another is one of the main objectives in the field of Metallosupramolecular Chemistry. In this work, we report two new neutral copper(II) helicates, [Cu2(L1)2]·4CH3CN and [Cu2(L2)2]·CH3CN, obtained by means of an electrochemical met...

The design of artificial helicoidal molecules derived from metal ions with biological properties is one of the objectives within metallosupramolecular chemistry. Herein, we report three zinc helicates derived from a family of bisthiosemicarbazone ligands with different terminal groups, Zn2(LMe)2∙2H2O 1, Zn2(LPh)2∙2H2O 2 and Zn2(LPhNO2)23, obtained...

The design of artificial helicoidal molecules derived from metal ions with biological properties is one of the objectives within Metallosupramolecular Chemistry. Herein, we report three zinc helicates derived from a family of bisthiosemicarbazone ligands with different terminal groups, Zn2(LMe)2∙2H2O 1, Zn2(LPh)2∙2H2O 2 and Zn2(LPhNO2)2 3, obtained...

Thiosemicarbazones are interesting organic skeletons due to their great coordinative versatility and their interesting biological and pharmacological properties, as well as their structural diversity. However, the isolation of their monovalent coinage metal complexes, such as Cu(I), Ag(I) and Au(I), is a partially studied field, since co-ligands wi...

We report two different approaches to isolate neutral and cationic mesocate-type metallosupramolecular architectures derived from coinage monovalent ions. For this purpose, we use a thiocarbohydrazone ligand, H2L (1), conveniently tuned with bulky phosphine groups to stabilize the MI ions and prevent ligand crossing to achieve the selective formati...

The mechanism of carbamate activation promoted by different metal ions has been explored in this work. The reaction of the carbamate ligand H2L with chloride metal salts (M = Ni, Cu, Zn, Cd) leads to the coordination of the metal ions to the ligand, causing hydrolysis of the systems. This self-immolation process results in mononuclear dihydrazone c...

Herein, we describe an approach for the on-demand disassembly of dimeric peptides using a palladium-mediated cleavage of a designed self-immolative linker. The utility of the strategy is demonstrated for the case of dimeric basic regions of bZIP transcription factors. While the dimer binds designed DNA sequences with good affinities, the peptide-DN...

The asymmetric hydrazone-thiosemicarbazone ligand H2L was synthesized in two stages by means of a double-condensation reaction. The potentially dianionic and pentadentate [N3SO] organic ligand H2L possesses two flexible bidentate [NS/NO] domains separated by a pyridine spacer, which could stabilize a wide variety of metal ions, giving rise to diffe...

As medidas de confinamento derivadas da pandemia da COVID afondaron na necesidade do desenvolvemento de ferramentas educativas en liña ás que o alumnado poda acceder en remoto autonomamente de maneira asíncrona. Neste artigo descríbese a nosa proposta dun curso aberto de química en liña a partir dun enfoque experimental, baseado principalmente en p...

We present two ligands containing a N-ethyl-4-(trifluoromethyl)benzenesulfonamide group attached to either a 6,6'-(azanediylbis(methylene))dipicolinic acid unit (H3DPASAm) or a 2,2'-(1,4,7-triazonane-1,4-diyl)diacetic acid macrocyclic platform (H3NO2ASAm). These ligands were designed to provide a pH-dependent relaxivity response upon complexation w...

Here, we report the application of surface-enhanced Raman scattering (SERS) spectroscopy as a rapid and practical tool for assessing the formation of coordinative adducts between nucleic acid guanines and ruthenium polypyridyl reagents. The technology provides a practical approach for the wash-free and quick identification of nucleic acid structure...

Over the past several years, transition‐metal‐mediated chemical reactions have been increasingly used for chemo‐ and regioselective modification of biomolecules. In this Minireview, by J. Rodríguez and M. Martínez‐Calvo on page 9792 ff., the recent developments in this rapidly evolving field have been summarized. While most biomolecule functionaliz...

When nanoparticles (NPs) are exposed to biological media proteins are adsorbed, forming a so-called protein corona (PC). This cloud of protein aggregates hampers the targeting and transport capabilities of the NPs, thereby compromising their biomedical applications. Therefore, there is a high interest in the development of technologies that allow t...

Four new fluorescent sensors (1–4) based on the 4-amino-1,8-naphthalimide fluorophores (Naps) have been synthesized based on the classical fluorophorespacer-receptor model. These four compounds all gave rise to emission bands centred at ca. 535 nm, which were found to be highly pH dependent, the emission being ‘switched on’ in acidic media, while b...

The cytosolic delivery of hydrophilic, anionic molecular probes and therapeutics is a major challenge in chemical biology and medicine. Herein, we describe the design and synthesis of peptide-cage hybrids that allow an efficient supramolecular binding, cell membrane translocation and cytosolic delivery of a number of anionic dyes, including pyranin...

A elaboración da táboa periódica actual foi un proceso complexo e longo no cal foron protagonistas moitos científicos e científicas. Entre eles atopábase o químico ruso Mendeleiev, que pasou á historia como o seu autor principal. Na actualidade, a táboa periódica permítenos clasificar aos elementos químicos de tal forma que as súas propiedades esta...

The effect of the ligand and/or metal-related factors on the formation of tristhiosemicarbazone metallosupramolecular complexes has been studied in this work. The crystal structures of zinc(II) and lead(II) tristhiosemicarbazone mesocates and a hydrolyzed cadmium(II) helicate let us better rationalize some factors involved in the selective formatio...

Transition-metal catalysis has changed the way in which chemical reactions can be accomplished. While most metal-catalyzed reactions have been achieved in organic solvents, recent work has demonstrated that many of these transformations can be made compatible with water. These discoveries have stimulated the search for metal catalysts that are capa...

Organometallic catalysis has allowed the development of an impressive number of chemical transformations that could not be achieved using classical methodologies. Most of these reactions have been accomplished in organic solvents, and in many cases in the absence of water, and under air-free conditions. The increasing pressure to develop more susta...

A facile one-pot synthesis of 3-amino-[1,2,4]-triazolo[4,3-a]pyridines from thiosemicarbazides through anion mediated synthesis is reported. Thiosemicarbazides derived from 2-hydrazino pyridine, 5-chloro 2-hydrazino pyridine, and 2-hydrazine quinoline were formed in situ as anion receptors in the presence of TBAF. Under microwave heating, thiosemic...

A facile one-pot synthesis of 3-amino-[1,2,4]- triazolo[4,3-a]pyridines from thiosemicarbazides through anion mediated synthesis is reported. Thiosemicarbazides derived from 2-hydrazino pyridine, 5-chloro 2-hydrazino pyridine, and 2-hydrazine quinoline were formed in situ as anion receptors in the presence of TBAF. Under microwave heating, thiosemi...

The development of Ru(ii) functionalized gold nanoparticles is described. These systems were found to be mono-disperse with a hydrodynamic radius of ca. 15 nm in water but gave rise to the formation of higher order structures in buffered solution. The interaction of with DNA was also studied by spectroscopic and microscopic methods and suggested th...

A series of enantiomeric btp-containing ligands [2,6-bis(1,2,3-triazol-4-yl)pyridines] were synthesized via a one-pot two-step copper-catalyzed amine-alkyne 'click' reaction. The Eu(III) and Tb(III) directed self-assembly formation of these ligands was studied in CH3CN by monitoring their various photophysical properties, including their emerging c...

The synthesis of five new 2,6-bis(1,2,3-triazol-4-yl)pyridine (btp) ligands is described: the self-assembly behaviour of the tri-methyl ester, 1, with Eu(III) showed the formation of a luminescent 1:3 Eu:btp complex, Eu13, which was studied in solution and in the solid state; while the tri-carboxylic acid, 2, formed a hydrogel and its corresponding...

Herein we present the use of lanthanide directed self-assembly formation (Ln(III) = Eu(III), Tb(III)) in the generation of luminescent supramolecular polymers, that when swelled with methanol give rise to self-healing supramolecular gels. These were analyzed by using luminescent and 1H NMR titrations studies, allowing for the identification of the...

The binding of asymmetrical and optically pure tridentate ligands (L = 1(S) and 1(R)) containing one carboxylic group and 2-naphthyl as an antenna to lanthanide ions (M = La(III) and Eu(III)) was studied in CH3CN, showing the successive formation of M:L, M:L2 and M:L3 stoichiometric species in solution. The europium complexes EuL3 were also synthes...

The synthesis and photophysical studies of two chiral Tröger's base (TB)-derived bis-naphthalimides 1 and 2 and the TB derivative 6, which was also characterized by X-ray crystal structure are presented. The enantiomers of both compounds 1 and 2 are separated by cation-exchange chromatography using CM Sephadex C25 as the stationary phase and sodium...

This review details the progress made in our laboratory in Dublin within the area of supramolecular lanthanide chemistry; where the main objective has been to develop functional lanthanide luminescent systems that emit within the visible or the near-infrared regions of the electromagnetic spectrum. The application of the lanthanide-centred assembly...

We have studied the factors that affect the formation of different metallosupramolecular architectures by metal direct self-assembly. A synthetic route has been developed to obtain mesocates or dihelicates selectively. For this purpose a series of five bisthiosemicarbazone ligands derived from 1,3-diacetylbenzene were designed and synthesised. Name...

The isolation of the first case of a ‘grid-of-helicates’ allowed us to rationalize the formation of extended 1D-chains or 2D-grid sheets of helicates with Cd(II) ions.

A unique case of a grid-of-mesocates sequentially assembled by supramolecular cobalt(II) meso-helical units connected through hydrogen bonding is reported.

A novel neutral triple-stranded hexanuclear copper(I) cluster helicate [Cu(I)(6)L(3)]·2CH(3)CN derived from a thiosemicarbazone ligand could be synthesized and crystallographically characterized. The MALDI mass spectrum of this complex suggests that the tetranuclear copper(I) cluster helicate [Cu(I)(4)L(2)] is also present in solution. These copper...

Water reduction can be electrochemically promoted by zinc under very mild conditions, as demonstrated by the formation of the complex [Zn(H(2)O)(6)][Zn(3)(L)(3)(mu(3)-O)], whose anion consists of a Zn(3)O(4) cluster incorporating a mu(3)-oxo anion.

A [4+4] double-stranded cadmium dihelicate was afforded from an easily accessible thiosemicarbazone ligand; its crystal structure reveals the assembly of two enantiomers into dihelicate pairs, these pairs being further connected into infinite linear chains.

Two new sulfonamide-type fluorescent chemosensors in organic media are reported. The two receptors, [N,N'-bis(2-tosylaminobenzylidene)-1,2-diaminoethane and N,N'-bis(2-tosylaminobenzylidene)-1,3-diamino-2-propanol], display marked changes in the fluorescence emission intensities as a result of deprotonation by basic anions, and show high selectivit...

The coordinative chemistry of the tridentate thiosemicarbazone ligand 2-pyridinecarboxaldehyde 4-N-ethylthiosemicarbazone (HL(Et)) has been explored by using an electrochemical methodology. All the complexes have been characterized using analytical and spectroscopic techniques. In the case of copper we have isolated two different complexes, with Cu...

A cobalt(II) thiosemicarbazonate mesocate has been structurally characterized as an unexpected mixture of conformational and linkage isomers. Moreover, we have shown that the absence of a nitrogen atom in the spacer of the helicand ligand H(2)L(a), enables the assembly of an achiral mesohelical complex in the case of Co(II) ions.

We have prepared some transition and post-transition metal complexes derived from the pentadentate thiosemicarbazone ligand bis(4-N-ethylthiosemicarbazone)-2,6-diacetylpyridine H(2)L(Et), by both chemical and electrochemical procedures. The complexes have been synthesised and fully characterised, including the crystal structures for the ligand H(2)...

The aim of the work described here was to test the general applicability of our recently reported route to cluster helicates and to carry out a systematic study to relate the structural and coordinative properties of the organic strands with the microarchitectures of the resulting cluster helicates. Nine new ZnII, CuI and AgI complexes were prepare...

The metal complexes studied in this report derive from the ligand 4‐ N ‐phenylthiosemicarbazone‐2‐pyridinecarboxaldehyde, abbreviated HL, and the transition and post‐transition metals manganese, iron, cobalt, nickel, copper, silver, zinc, cadmium and lead. The new complexes were obtained by an electrochemical procedure and were found to be of the f...

The interaction of the transition and post‐transition metals manganese, iron, cobalt, nickel, zinc, cadmium and lead, with the ligand 4‐ N ‐methylthiosemicarbazone‐2‐pyridinecarboxaldehyde (HL) through an electrochemical procedure has been investigated. The novel complexes obtained via this synthetic route have the general formulae [M(L) 2 ](H 2 O)...