Juan-Carlos Rodríguez-Ubis

Lanthanide complexes of polycarboxylate-bearing dipyrazolylpyridine ligands with near-unity luminescence quantum yields: the effect of pyridine substitution.

The title complexes displayed a marked dependence of their luminescence properties upon pyridine substitution. The ligand with the 4-carbamoyl-substituted pyridine showed a long-lived luminescence of near-unity quantum yield for Tb3- and quite reasonable values for Eu3+, Sm3+ and Dy3-, thus making it an excellent candidate for a luminescent probe to be attached to biomolecules by a peptide-like linkage.

Synthesis and photochemical properties of new coumarin-derived ionophores and their alkaline-earth and lanthanide complexes

Several new ionophores derived from crown ethers and iminodiacetic subunits attached to 3-aroylcoumarins have been synthesized and fully characterized. The alkaline-earth complexes of these new ligands were studied from their UV–visible and fluorescence data. Some systems displayed strong bathochromic shifts upon complexation with Mg 2+ that may make them useful signaling devices of this cation. The corresponding Eu 3+ and Tb 3+ chelates were easily formed and their photophysical properties were measured. In all the cases, lanthanide emission lifetimes were in the range of milliseconds albeit quantum yields were low. Possible energy-transfer mechanisms are discussed.

Palladium(II) coordination and cyclometallated complexes derived from 3- and 5-aryl-substituted pyrazoles

Palladium(II) coordination complexes of nine 3- or 5-arylpyrazoles (phenyl, 2-bromophenyl, or 3-methoxyphenyl), as well as of 3,5-diphenylpyrazole, are reported. A cis-trans mixture of [PdL2Cl2] isomers is found in the case of 3-aryl-1-methylpyrazoles, the cis-isomers being transformed into trans by heating. Only trans isomers are isolated with the other ligands. Cyclopalladation of 3-ary]-1-methylpyrazoles can be performed with palladium(II) acetate, and the resultant μ-acetate bridged dimers can be transformed into μ-chloro bridged dimers or acetylacetonate monomers. The structures of the complexes have been characterized by 1H- and 13C-NMR spectroscopy.

Magnesium optical one-shot sensor based on a coumarin chromoionophore

The characterization of a new irreversible optical absorption-based one-shot sensor for magnesium is described. The magnesium photoactive probe is 7-diethylamino-3-(3,4-ethylendioxybenzoyl)coumarin immobilized in a plasticized polymeric membrane. The magnesium selectivity can be explained in terms of size and charge density of magnesium and charge-separated resonance forms contribution in the excited state of coumarin. The selectivity obtained for magnesium over a variety of naturally occurring species in natural waters meets the requirements for the determination of this ion in water. The one-shot sensor responds between 0.14 and 14mgL(-1) with a sensor-to-sensor reproducibility of 1.3% as [Formula: see text] , at the medium level of the range. The performance of the optical one-shot sensor was tested in the analysis of magnesium in different types of natural waters and soft drinks validating results against a reference procedure.

Palladium(II) coordination and cyclometallated complexes derived from 1-tert-butylpyrazole

The synthesis and characterization of a number of new coordination compounds of PdII with the nitrogen donor 1-tert-butylpyrazole (tBuPzH) are described. Compounds are trans-[Pd(tBuPzH)2Cl2] and the cyclometallated structures [Pd2(tBuPz)2(AcO)2] and [Pd3(tBuPz)2(AcO)4]. All these complexes are mixtures of syn and anti isomers. Also, the chloro-bridged complex [Pd2(tBuPz)2Cl2] has been isolated as an equilibrium mixture of cis and trans isomers. The compounds have been studied by variable temperature 1H- and 13C-NMR spectroscopy.

Synthesis of macrobicyclic ligands containing pyrazole subunits: the N,N′-bipyrazolyl cryptand

The pyrazolyl cryptands [bpz.bpz.bpz](1) and [2.2.bpz](2) have been obtained in a one-step, non high-dilution macrobicyclization reaction, from a 1,1′-bipyrazole derivative; similarly, tripodal ligands (7)–(9) with pyrazole structure are described.

The use of laminar inorganic salts to make organic molecules display new properties at the supramolecular level in the solid state

The design of porous solids of controlled molecular geometry for umpteen applications is a challenge of enormous technological and scientific importance. The placing of organic molecules between the layers of certain inorganic salts leads to enduring solid materials where the confinement makes the organic molecules change their properties or even display new ones at the supramolecular level. Past and ongoing results of our research group concerning the chemistry of metal phosphates/phosphonates are reviewed in relation with recognition, chemically-driven porosity changes, chiral memory and supramolecular chirality, luminescence signaling, photoinduced electron-transfer, gas storage and drug confinement.