0000000001299846
AUTHOR
Raquel Belda
Homo- and heterobinuclear Cu2+ and Zn2+ complexes of abiotic cyclic hexaazapyridinocyclophanes as SOD mimics
The new receptor 3,7,11,15,19,23-hexaaza-1(2,6)-pyridinacyclotetracosaphane (L1) containing a complete sequence of propylenic chains has been synthesised. The acid–base behaviour and Cu2+ and Zn2+ coordination have been analysed by potentiometric measurements in 0.15 M NaClO4 for L1 and for the related compounds 3,7,11,14,18,22-hexaaza-1(2,6)-pyridinacyclotricosaphane (L2), 3,7,10,13,16,20-hexaaza-1(2,6)-pyridinacycloheneicosaphane (L3) and 3,7,10,12,15,19-hexaaza-1(2,6)-pyridinacycloicosaphane (L4). The crystal structure of [(CuH4L2)(H2O)(ClO4)](ClO4)5·3H2O shows an interesting combination of a metal ion coordinated by the pyridine nitrogen atom and the adjacent amine groups of the chain, …
Synthesis and Structural Characterization of a Cyclen-Derived Molecular Cage
Reaction of a tetrafunctionalized cyclen derivative containing four aldehyde groups with an appropriate diamine followed by reduction and demetalation highly efficiently affords a bis(cyclen)-derived molecular cage. Potentiometric investigations show that this compound forms dimetallic complexes with copper(II), with the two metal ions selectively coordinated to the cyclen units. X-ray crystallography indicates that these complexes could give rise to new cascade complexes after incorporation of anions between the metal centers.
Guanosine-5'-Monophosphate Polyamine Hybrid Hydrogels: Enhanced Gel Strength Probed by z-Spectroscopy.
The self-assembling tendencies of guanosine-5'-monophosphate (GMP) can be drastically increased using polyamines, with potential applications in the production of biocompatible smart materials, as well as for the design of anti-tumoral drugs based on G-quadruplex stabilization. Results from scanning electron microscopy (SEM), wide angle X-ray scattering (WAXS), rheology and nuclear magnetic resonance (NMR) z-spectroscopy studies are presented.
Intermolecular binding modes in a novel [1 + 1] condensation 1H-pyrazole azamacrocycle: a solution and solid state study with evidence for CO2 fixation.
The synthesis of a novel cyclophane (L1) consisting of a 1H-pyrazole moiety linked through methylene groups to a 1,5,9,13-tetraazadecane chain is described. As far as we know, this is one of the first reported syntheses of a [1 + 1] condensation 1H-pyrazole azamacrocyclic ligand. The crystal structures of the complexes [Cu2(H(H(-1)L1))(H(-1)L1)](ClO4)3·3.75H2O (1) and ([Cu2(H(H(-1)L1))(0.5)(H(-1)L1)(1.5)]2(ClO4)3Br2·4.2H2O (2) show that Cu(2+) coordination leads to formation of 2:2 Cu(2+):L dinuclear dimeric complexes in which the 1H-pyrazole units lose a proton behaving as bis(monodentate) bridging ligands. Unlike previously reported complexes of [2 + 2] pyrazole azamacrocycles, the pyrazo…
A water molecule in the interior of a 1H-pyrazole Cu2+ metallocage
Water has a great tendency to associate through hydrogen bonding with water molecules or other hydrogen bond donor or acceptor groups. Here the case of a water molecule encapsulated in the interior of a metallocage receptor is presented. The association of four copper(II) ions and two aza-macrocyclic receptors in which two 1H-pyrazole units are connected by cadaverine diamines leads to the inclusion of a water molecule into the cage, as proved by X-ray analysis and infrared spectroscopy. The included water molecule shows no hydrogen bonding with any component of the cage presenting only a weak hydrogen bond with an oxygen atom of a perchlorate counter-anion. The IR stretching vibrations pre…
Exceedingly Fast Oxygen Atom Transfer to Olefins via a Catalytically Competent Nonheme Iron Species
El mateix article està publicat en alemany a l'edició alemanya d' 'Angewandte Chemie' (ISSN 0044-8249, EISSN 1521-3757), 2016, vol. 128, núm. 21, p.6418–6422. DOI http://dx.doi.org/10.1002/ange.201601396 The reaction of [Fe(CF3SO3)2(PyNMe3)] with excess peracetic acid at −40 °C leads to the accumulation of a metastable compound that exists as a pair of electromeric species, [FeIII(OOAc)(PyNMe3)]2+ and [FeV(O)(OAc)(PyNMe3)]2+, in fast equilibrium. Stopped-flow UV/Vis analysis confirmed that oxygen atom transfer (OAT) from these electromeric species to olefinic substrates is exceedingly fast, forming epoxides with stereoretention. The impact of the electronic and steric properties of the subs…
Receptors for Nucleotides
Recognition and activation of nucleotides by polyammonium receptors constitute an important target in supramolecular chemistry since the very beginning of this field. Nucleotides have three components: (i) the polyphosphate chain, (ii) the sugar moiety, and (iii) the nucleobase, which permit their multipoint binding through attractions between opposite charges, hydrogen bonding, π-stacking, CH–π interactions, and so on. In this chapter, different receptors for nucleotides, most but not all of them consisting polyamines, are examined, focusing on their molecular structure that enables different binding modes to be operated. Also, a number of examples of nucleotide binding through metal compl…
Luminescent supramolecular heterometallic macrocycles and their encapsulation on cholate gels
The metal complex formed by coordination of Zn(II) to 1,7-bis(4-methylpyridine)-4-(2- naphthylmethyl)-1,4,7-triazaheptane (ZnL2+) was reacted in aqueous solution with [Pd(NO3)2(en)] and [Pt(NO3)2(en)] salts to form the self-assembled heterometallic macrocycles [Zn2L2Pd2(en)2]8+ and [Zn2L2Pt2(en)2]8+, respectively. Pd(II) and Pt(II)- coordination modulates the original emission of ZnL2+ arising from the presence of the naphthalene chromophore and the formation of the macrocycles can be monitored due to the PET process occurring with coordination of Pd(II) and Pt(II) to the pyridine units of ZnL2+. Additionally, several studies reveal that these heteromacrocycles can be encapsulated in Zn(II)…
Zn(II)-coordination and fluorescence studies of a new polyazamacrocycle incorporating 1H-pyrazole and naphthalene units.
The synthesis and Zn(2+) coordination properties of a new macrocycle (L1) obtained by dipodal (2 + 2) condensation of the polyamine 3-(naphthalen-2-ylmethyl)pentane-1,5-diamine with 1H-pyrazole-3,5-dicarbaldehyde are reported. pH-metric studies show that L1 bears five measurable protonation steps in the 2.0-11.0 pH range. Fluorescence emission studies indicate that the removal of the first proton from the H(5)L1(5+) species leads to a significant decrease in the emission due to a photoinduced electron transfer process. Addition of Zn(2+) promotes a boat-like conformation that approaches both fluorophores and facilitates the formation of an excimer which reaches its highest emission for a 1 …
Synthesis, Protonation and Cu II Complexes of Two Novel Isomeric Pentaazacyclophane Ligands: Potentiometric, DFT, Kinetic and AMP Recognition Studies
The synthesis and coordination chemistry of two novel ligands, 2,6,9,12,16-pentaaza[17]metacyclophane (L1) and 2,6,9,12,16-pentaaza[17]paracyclophane (L2), is described. Potentiometric studies indicate that L1 and L2 form a variety of mononuclear complexes the stability constants of which reveal a change in the denticity of the ligand when moving from L1 to L2, a behaviour that can be qualitatively explained by the inability of the paracyclophanes to simultaneously use both benzylic nitrogen atoms for coordination to a single metal centre. In contrast, the formation of dinuclear hydroxylated complexes is more favoured for the paraL2 ligand. DFT calculations have been carried out to compare …
Tritopic phenanthroline and pyridine tail-tied aza-scorpiands
The synthesis of two new tritopic double-scorpiand receptors in which two equivalent 5-(2-aminoethyl)-2,5,8-triaza[9]-(2,6)-pyridinophane moieties have been linked with 2,6-dimethylpyridine (L1) or 2,9-dimethylphenanthroline (L2) units is reported for the first time. Their acid-base behaviour and Zn(2+) coordination chemistry have been studied by pH-metric titrations, molecular dynamic calculations, NMR, UV-Vis and steady-state fluorescence techniques. L1 and L2 behave, respectively, as hexaprotic and heptaprotic bases in the experimental conditions used (298.1 +/- 0.1 K, 0.15 mol dm(-3) NaCl, pH range under study 2.0-11.0). These ligands are able to form mono-, bi- and trinuclear Zn(2+) co…
From isolated 1H-pyrazole cryptand anion receptors to hybrid inorganic-organic 1D helical polymeric anion receptors
We report a novel 1-D helical coordination polymer formed by protonated polyamine 1H-pyrazole cryptands interconnected by Cu2+ metal ions that are able to encapsulate anionic species behaving as a multianion receptor. Switching from a monomeric receptor to a polymeric receptor is activated by metal ions and pH.
Synthesis and coordination properties of an azamacrocyclic Zn(II) chemosensor containing pendent methylnaphthyl groups
The synthesis of a polyazamacrocycle constituted by two diethylenetriamine bridges functionalized at their central nitrogen with naphth-2-ylmethyl units and interconnected through 2,6-dimethylpyridine spacers (L1) is reported. The protonation behaviour of the new macrocycle in water and in water-ethanol 70/30 v/v mixed solvent has been examined by means of pH-metric, UV-Vis and steady-state fluorescence techniques. The fluorescence emission is slightly quenched following the deprotonation of the central tertiary amines and more deeply quenched upon deprotonation of the secondary amino groups. pH-Metric titrations show that in water-ethanol 70/30 v/v L1 forms stable mononuclear complexes wit…
>3 + 1 = 6 + 2> In Cu(ii) coordination chemistry of 1H-pyrazole aza cryptands
A polyazamacrocycle formed from two tris(2-aminoethyl)amine units connected by 1H-pyrazole units shows unique hexanuclear Cu(ii) complexes by combination of two binuclear Cu(ii) cryptand complexes through pyrazolate moieties belonging to both cryptands. The formation of these dimeric entities has been proven both in solution by potentiometric studies and mass spectroscopy and in the solid state by X-ray diffraction of crystals of three different batches of formulae [Cu6(H-3L)2(H2O)2](TsO)6·22H2O (2), [Cu6(H-3L)2(NO3)2](NO3)4·2H2O (3) and [Cu6(H-3L)2Cl2]Cl4·(C4H5N3O2)2·14.35H2O (4). The hexanuclear unit in 2 and 4 can be viewed like three magnetically independent binuclear complexes with J =…
Hybrid GMP–polyamine hydrogels as new biocompatible materials for drug encapsulation
Here we present the preparation and characterization of new biocompatible materials for drug encapsulation. These new gels are based on positively charged [1+1] 1H-pyrazole-based azamacrocycles which minimise the electrostatic repulsions between the negatively charged GMP molecules. Rheological measurements confirm the electroneutral hydrogel structure as the most stable for all the GMP-polyamine systems. Nuclear magnetic resonance (NMR) was employed to investigate the kinetics of the hydrogel formation and cryo-scanning electron microscopy (cryo-SEM) was used to obtain information about the hydrogel morphology, which exhibited a non-homogeneous structure with a high degree of cross-linking…
CCDC 1431346: Experimental Crystal Structure Determination
Related Article: Alexander Ganß, Raquel Belda, Javier Pitarch, Richard Goddard, Enrique García-España, and Stefan Kubik|2015|Org.Lett.|17|5850|doi:10.1021/acs.orglett.5b03027
CCDC 973978: Experimental Crystal Structure Determination
Related Article: Raquel Belda, Javier Pitarch-Jarque, Conxa Soriano, José M. Llinares, Salvador Blasco, Jesús Ferrando-Soria, and Enrique García-España|2013|Inorg.Chem.|52|10795|doi:10.1021/ic400645t
CCDC 973974: Experimental Crystal Structure Determination
Related Article: Raquel Belda, Javier Pitarch-Jarque, Conxa Soriano, José M. Llinares, Salvador Blasco, Jesús Ferrando-Soria, and Enrique García-España|2013|Inorg.Chem.|52|10795|doi:10.1021/ic400645t
CCDC 1468808: Experimental Crystal Structure Determination
Related Article: Javier Pitarch-Jarque, Raquel Belda, Salvador Blasco, Pilar Navarro, Roberto Tejero, José Miguel Junquera-Hernández, Vicente Pérez-Mondéjar, Enrique García-España|2016|New J.Chem.|40|5670|doi:10.1039/C5NJ03234B
CCDC 934155: Experimental Crystal Structure Determination
Related Article: Raquel Belda,Salvador Blasco,Begona Verdejo,Hermas R. Jimenez,Antonio Domenech-Carbo,Conxa Soriano,Julio Latorre,Carmen Terencio,Enrique Garcia-Espana|2013|Dalton Trans.|42|11194|doi:10.1039/C3DT51012C
CCDC 973976: Experimental Crystal Structure Determination
Related Article: Raquel Belda, Javier Pitarch-Jarque, Conxa Soriano, José M. Llinares, Salvador Blasco, Jesús Ferrando-Soria, and Enrique García-España|2013|Inorg.Chem.|52|10795|doi:10.1021/ic400645t
CCDC 892312: Experimental Crystal Structure Determination
Related Article: Javier Pitarch-Jarque, Raquel Belda, Salvador Blasco, Pilar Navarro, Roberto Tejero, José Miguel Junquera-Hernández, Vicente Pérez-Mondéjar, Enrique García-España|2016|New J.Chem.|40|5670|doi:10.1039/C5NJ03234B
CCDC 983275: Experimental Crystal Structure Determination
Related Article: Javier Pitarch-Jarque, Raquel Belda, Laura García-España, José M. Llinares, FangFang Pan, Kari Rissanen, Pilar Navarro, Enrique García-España|2015|Dalton Trans.|44|7761|doi:10.1039/C5DT00763A
CCDC 1429442: Experimental Crystal Structure Determination
Related Article: Alexander Ganß, Raquel Belda, Javier Pitarch, Richard Goddard, Enrique García-España, and Stefan Kubik|2015|Org.Lett.|17|5850|doi:10.1021/acs.orglett.5b03027
CCDC 1030676: Experimental Crystal Structure Determination
Related Article: Javier Pitarch-Jarque, Raquel Belda, Laura García-España, José M. Llinares, FangFang Pan, Kari Rissanen, Pilar Navarro, Enrique García-España|2015|Dalton Trans.|44|7761|doi:10.1039/C5DT00763A
CCDC 1468807: Experimental Crystal Structure Determination
Related Article: Javier Pitarch-Jarque, Raquel Belda, Salvador Blasco, Pilar Navarro, Roberto Tejero, José Miguel Junquera-Hernández, Vicente Pérez-Mondéjar, Enrique García-España|2016|New J.Chem.|40|5670|doi:10.1039/C5NJ03234B
CCDC 983272: Experimental Crystal Structure Determination
Related Article: Javier Pitarch-Jarque, Raquel Belda, Francesc Lloret, Jesús Ferrando-Soria, Pilar Navarro, Alberto Lopera, Enrique García-España|2015|Dalton Trans.|44|3378|doi:10.1039/C4DT03650F
CCDC 983271: Experimental Crystal Structure Determination
Related Article: Javier Pitarch-Jarque, Raquel Belda, Francesc Lloret, Jesús Ferrando-Soria, Pilar Navarro, Alberto Lopera, Enrique García-España|2015|Dalton Trans.|44|3378|doi:10.1039/C4DT03650F
CCDC 892315: Experimental Crystal Structure Determination
Related Article: Javier Pitarch-Jarque, Raquel Belda, Salvador Blasco, Pilar Navarro, Roberto Tejero, José Miguel Junquera-Hernández, Vicente Pérez-Mondéjar, Enrique García-España|2016|New J.Chem.|40|5670|doi:10.1039/C5NJ03234B
CCDC 1431345: Experimental Crystal Structure Determination
Related Article: Alexander Ganß, Raquel Belda, Javier Pitarch, Richard Goddard, Enrique García-España, and Stefan Kubik|2015|Org.Lett.|17|5850|doi:10.1021/acs.orglett.5b03027
CCDC 983274: Experimental Crystal Structure Determination
Related Article: Javier Pitarch-Jarque, Raquel Belda, Francesc Lloret, Jesús Ferrando-Soria, Pilar Navarro, Alberto Lopera, Enrique García-España|2015|Dalton Trans.|44|3378|doi:10.1039/C4DT03650F
CCDC 983273: Experimental Crystal Structure Determination
Related Article: Javier Pitarch-Jarque, Raquel Belda, Francesc Lloret, Jesús Ferrando-Soria, Pilar Navarro, Alberto Lopera, Enrique García-España|2015|Dalton Trans.|44|3378|doi:10.1039/C4DT03650F
CCDC 892316: Experimental Crystal Structure Determination
Related Article: Javier Pitarch-Jarque, Raquel Belda, Salvador Blasco, Pilar Navarro, Roberto Tejero, José Miguel Junquera-Hernández, Vicente Pérez-Mondéjar, Enrique García-España|2016|New J.Chem.|40|5670|doi:10.1039/C5NJ03234B
CCDC 973975: Experimental Crystal Structure Determination
Related Article: Raquel Belda, Javier Pitarch-Jarque, Conxa Soriano, José M. Llinares, Salvador Blasco, Jesús Ferrando-Soria, and Enrique García-España|2013|Inorg.Chem.|52|10795|doi:10.1021/ic400645t
CCDC 973977: Experimental Crystal Structure Determination
Related Article: Raquel Belda, Javier Pitarch-Jarque, Conxa Soriano, José M. Llinares, Salvador Blasco, Jesús Ferrando-Soria, and Enrique García-España|2013|Inorg.Chem.|52|10795|doi:10.1021/ic400645t