ON/OFF metal-triggered molecular tweezers for fullerene recognition

Producción CientíficaHerein, we report molecular tweezers for fullerene recognition based on 2,2′-bipyridine-bearing corannulene motifs. The syn or anti confirmation can be selected simply by Cu(I) coordination/decoordination, thus controlling the fullerene recognition capability of the system on demand and leading to the formation of effective metal-triggered ON/OFF molecular tweezers.We thank the Spanish Ministry of Science, Innovation and Universities (MCIU) for funding (project numbers PGC2018096880-A-I00, MCIU/AEI/FEDER, UE, PGC2018-099470-B-I00, and MCIU/AEI/FEDER, UE). R. G.-R. acknowledges the Spanish MINECO/AEI and the European Union (ESF) for a Ramón y Cajal contract (RYC-2015-19035). H. B. acknowledges the Alfonso Martín Escudero Foundation for a postdoctoral fellowshi

Copper complexes for the promotion of iminopyridine ligands derived from β-alanine and self-aldol additions: relaxivity and cytotoxic properties

Producción CientíficaIn the study presented herein, we explore the ability of copper complexes with coordinated pyridine-2-carboxaldehyde (pyca) or 2-acetylpyridine (acepy) ligands to promote the addition of amines (Schiff condensation) and other nucleophiles such as alcohols (hemiacetal formation). Distinct reactivity patterns are observed: unlike pyca complexes, acepy copper complexes can promote self-aldol addition. The introduction of a flexible chain via Schiff condensation with β-alanine allows the possibility of chelate ring ring-opening processes mediated by pH. Further derivatization of the complex [CuCl(py-2-C(H)[double bond, length as m-dash]NCH2CH2COO)] is possible by replacing its chloride ligand with different pseudohalogens (N3−, NCO− and NCS−). In addition to the change in their magnetism, which correlates with their solid-state structures, more unexpected effects in their cytotoxicity and relaxitivities are observed, which determines their possibility to be used as MRI contrast agents. The replacement of a chloride by another pseudohalogen, although a simple strategy, can be used to critically change the cytotoxicity of the Schiff base copper (II) complex and its selectivity towards specific cell lines.Ministerio de Ciencia, Innovación y Universidades - Agencia Estatal de Investigación - FEDER (projects PGC2018-096880-A-I00 / PGC2018-099470-B-I00)Ministerio de Economía, Industria y Competitividad - Agencia Estatal de Investigación - FEDER - UE (contract RYC-2015-19035)Junta de Castilla y León (project VA130G18)Laboratory of Excellence of Nanostructures in Interaction with their Environment (project ANR-11-LABX-0058-NIE within the Investissement d'Avenir program ANR-10-IDEX-0002-02)

Phenylisoxazole-3/5-Carbaldehyde Isonicotinylhydrazone Derivatives: Synthesis, Characterization, and Antitubercular Activity

14 pags, 5 figs, 3 tabs, 1 schEight new phenylisoxazole isoniazid derivatives, 3-(2′-fluorophenyl)isoxazole-5-carbaldehyde isonicotinylhydrazone (1), 3-(2′-methoxyphenyl)isoxazole-5-carbaldehyde isonicotinylhydrazone (2), 3-(2′-chlorophenyl)isoxazole-5-carbaldehyde isonicotinylhydrazone (3), 3-(3′-clorophenyl)isoxazole-5-carbaldehyde isonicotinylhydrazone (4), 3-(4′-bromophenyl)isoxazole-5-carbaldehyde isonicotinylhydrazone (5), 5-(4′-methoxiphenyl)isoxazole-3-carbaldehyde isonicotinylhydrazone (6), 5-(4′-methylphenyl)isoxazole-3-carbaldehyde isonicotinylhydrazone (7), and 5-(4′-clorophenyl)isoxazole-3-carbaldehyde isonicotinylhydrazone (8), have been synthesized and characterized by FT-IR, 1H-NMR, 13C-NMR, and mass spectral data. The 2D NMR (1H-1H NOESY) analysis of 1 and 2 confirmed that these compounds in acetone-d6 are in the trans(E) isomeric form. This evidence is supported by computational calculations which were performed for compounds 1-8, using DFT/B3LYP level with the 6-311++G(d,p) basis set. The in vitro antituberculous activity of all the synthesized compounds was determined against the Mycobacterium tuberculosis standard strains: sensitive H37Rv (ATCC-27294) and resistant TB DM97. All the compounds exhibited moderate bioactivity (MIC = 0.34-0.41 μM) with respect to the isoniazid drug (MIC = 0.91 μM) against the H37Rv sensitive strain. Compounds 6 (X = 4′-OCH3) and 7 (X = 4′-CH3) with MIC values of 12.41 and 13.06 μM, respectively, were about two times more cytotoxic, compared with isoniazid, against the resistant strain TB DM97.W. H. and F. C. acknowledge Universidad de Lima Scientific Research Institute for the financial support to carry out this research work. E. S. thanks Financiamiento Basal para Centros Cientificos y Tecnologicos de Excelencia, AFB10008. J. Z. D. thanks Consejo Superior de Investigacion Cientifica (CSIC, Spain). S. O. thanks Ministerio de Ciencias, Innovacion y Universidades (MICINN (RTI2018-094356-B-C21)) and Cabildo de Tenerife (Agust ' in de Betancourt Program).Peer reviewe

A Tris(3-pyridyl)stannane as a Building Block for Heterobimetallic Coordination Polymers and Supramolecular Cages

The systematic assembly of supramolecular arrangements is a persistent challenge in modern coordination chemistry, especially where further aspects of complexity are concerned, as in the case of large molecular mixed‐metal arrangements. One targeted approach to such heterometallic complexes is to engineer metal‐based donor ligands of the correct geometry to build 3D arrangements upon coordination to other metals. This simple idea has, however, only rarely been applied to main group metal‐based ligand systems. Here, we show that the new, bench‐stable tris(3‐pyridyl)stannane ligand PhSn(3‐Py)3 (3‐Py=3‐pyridyl) provides simple access to a range of heterometallic SnIV/transition metal complexes, and that the presence of weakly coordinating counter anions can be used to build discrete molecular arrangements involving anion encapsulation. This work therefore provides a building strategy in this area, which parallels that of supramolecular transition metal chemistry

Mutational spectrum of the SPG4 (SPAST) and SPG3A (ATL1) genes in Spanish patients with hereditary spastic paraplegia

<p>Abstract</p> <p>Background</p> <p>Hereditary Spastic Paraplegias (HSP) are characterized by progressive spasticity and weakness of the lower limbs. At least 45 loci have been identified in families with autosomal dominant (AD), autosomal recessive (AR), or X-linked hereditary patterns. Mutations in the <it>SPAST </it>(<it>SPG4</it>) and <it>ATL1 </it>(<it>SPG3A</it>) genes would account for about 50% of the ADHSP cases.</p> <p>Methods</p> <p>We defined the <it>SPAST </it>and <it>ATL1 </it>mutational spectrum in a total of 370 unrelated HSP index cases from Spain (83% with a pure phenotype).</p> <p>Results</p> <p>We found 50 <it>SPAST </it>mutations (including two large deletions) in 54 patients and 7 <it>ATL1 </it>mutations in 11 patients. A total of 33 of the <it>SPAST </it>and 3 of the <it>ATL1 </it>were new mutations. A total of 141 (31%) were familial cases, and we found a higher frequency of mutation carriers among these compared to apparently sporadic cases (38% vs. 5%). Five of the <it>SPAST </it>mutations were predicted to affect the pre-mRNA splicing, and in 4 of them we demonstrated this effect at the cDNA level. In addition to large deletions, splicing, frameshifting, and missense mutations, we also found a nucleotide change in the stop codon that would result in a larger ORF.</p> <p>Conclusions</p> <p>In a large cohort of Spanish patients with spastic paraplegia, <it>SPAST </it>and <it>ATL1 </it>mutations were found in 15% of the cases. These mutations were more frequent in familial cases (compared to sporadic), and were associated with heterogeneous clinical manifestations.</p

pH-driven dynamic stereoinduction: epimerization upon dimerization in rhenium(i) complexes

Stereochemistry at the metal centre in a Re(I) complex can be modified by manipulating the pH: while acidic conditions favour a monomeric system, basic conditions induce a dimerization which concomitantly epimerizes the metal centre.Peer reviewe

Intramolecular carboboration of carbonylligands to form boroxycarbenes

A formal direct carboboration of carbonyl ligands to form manganese boroxycarbenes in a one-pot fashion is reported.Peer reviewe

Stereoselective Aldol Addition to Rhenium(I) Complexes and Reversible Dimerization with Epimerization of the Metal Center

Herein, we report several examples of stereoselective aldol additions of aldehydes or ketones to ReI tricarbonyl complexes to form monomeric derivatives in good yields. The metal‐centered chirality defines the final stereochemistry of the carbon atom of the monomeric ReI complex after the addition. However, it cannot control the resulting stereochemistry of the enolate part, and thus, if the α‐carbon atom of the reagent is prochiral, a mixture of diastereoisomers is obtained. On the other hand, all of the monomeric complexes can be reversibly dimerized in basic media to form cis dimers, for which an epimerization of the metal‐centered chirality is required in order to avoid steric congestion. All of these results are supported by exhaustive crystallographic analysis.This research was supported by the Spanish Ministerio de Ciencia e Innovación (CTQ2009‐12111) and Junta de Castilla y León (VA070 A08 and GR Excelencia 125). R.G.‐R. and C.M.A. wish to acknowledge an MEC‐FPU grant and a Ramón y Cajal contract.Peer Reviewe

Cation- and Anion-Mediated Supramolecular Assembly of Bismuth and Antimony Tris(3-pyridyl) Complexes.

Funder: Universidad de ValladolidThe use of antimony and bismuth in supramolecular chemistry has been largely overlooked in comparison to the lighter elements of Group 15, and the coordination chemistry of the tripodal ligands [Sb(3-py)3] and [Bi(3-py)3] (L) containing the heaviest p-block element bridgehead atoms has been unexplored. We show that these ligands form a common hybrid metal-organic framework (MOF) structure with Cu(I) and Ag(I) (M) salts of weakly coordinating anions (PF6-, SbF6-, and OTf-), composed of a cationic substructure of rhombic cage (M)4(L)4 units linked by Sb/Bi-M bonding. The greater Lewis acidity of Bi compared to Sb can, however, allows anion···Bi interactions to overcome Bi-metal bonding in the case of BF4-, leading to collapse of the MOF structure (which is also seen where harder metals like Li+ are employed). This study therefore provides insight into the way in which the electronic effects of the bridgehead atom in these ligand systems can impact their supramolecular chemistry

Indole-3-carbaldehyde Semicarbazone Derivatives: Synthesis, Characterization, and Antibacterial Activities

9 pags., 2 figs., 2 tabs.Four indole-3-carbaldehyde semicarbazone derivatives, 2-((5-bromo-1H-indol-3-yl)methylene)hydrazinecarboxamide (1), 2-((5-chloro-1H-indol-3-yl)methylene)hydrazinecarboxamide (2), 2-((5-methoxy-1H-indol-3-yl)methylene)hydrazinecarboxamide (3), and 2-((4-nitro-1H-indol-3-yl)methylene)hydrazinecarboxamide (4) were synthesized and characterized by ESI-MS and spectroscopic (FT-IR, H NMR, and C NMR) techniques. The two-dimensional NMR (in acetone-d) spectral data revealed that the molecules 1 and 2 in solution are in the cisE isomeric form. This evidence is supported by DFT calculations at the B3LYP/6-311++G(d,p) level of theory where it was shown that the corresponding most stable conformers of the synthesized compounds have a cisE geometrical configuration, in both the gas and liquid (acetone and DMSO) phases. The in vitro antibacterial activity of compounds 1-4 was determined against Gram-positive (Staphylococcus aureus and Bacillus subtilis) and Gram-negative (Pseudomonas aeruginosa and Escherichia coli) bacteria. Among all the tested semicarbazones, 1 and 2 exhibited similar inhibitory activities against Staphylococcus aureus (MIC = 100 and 150 μg/mL, respectively) and Bacillus subtilis (MIC = 100 and 150 μg/mL, respectively). On the other hand, 3 and 4 were relatively less active against the tested bacterial strains compared with 1, 2, and tetracycline.W. H. and F. C. thank the Universidad de Lima Scientific Research Institute for financial support to carry out this research work. E. S. thanks Financiamiento Basal para Centros Cientıficos y Tecnologicos de Excelencia, FB0807. ´ J. Z. D. thanks the Consejo Superior de Investigacion´ Cientıfica (CSIC) of Spain. S.O. thanks the Ministry of Science, Innovation, and Universities (MICINN (RTI2018- 094356-B-C21) as well as the Cabildo de Tenerife (Agustın de Betancourt Program) for financial support