Juan J. Fiol

Bio: Juan J. Fiol is an academic researcher from University of the Balearic Islands. The author has contributed to research in topics: Ligand & Non-covalent interactions. The author has an hindex of 21, co-authored 69 publications receiving 1307 citations. Previous affiliations of Juan J. Fiol include Spanish National Research Council.

Crystal structures and DFT calculations of new chlorido-dimethylsulfoxide-M(III) (M = Ir, Ru, Rh) complexes with the N-pyrazolyl pyrimidine donor ligand: kinetic vs. thermodynamic isomers.

Abstract: New chlorido-dimethylsulfoxide-iridium(III), ruthenium(III) and rhodium(III) complexes with the 2-(1H-pyrazol-1-yl)-pyrimidine (pyrapyr) ligand (OC-6-N1)-[RhIIICl3(DMSO-κS)(pyrapyr)] (1a, N = 3 and 1b, N = 4); (OC-6-N1)-[RuIIICl3(DMSO-κS)(pyrapyr)] (2a, N = 3 and 2b, N = 4) and (OC-6-N1)-[IrIIICl3(DMSO-κS)(pyrapyr)] (3a, N = 3 and 3b, N = 4) have been synthesized and characterized by spectroscopic techniques and by single crystal X-ray diffraction studies (1a, 1b, 2a, 2b, a disordered crystal 3a/3b and a cocrystal 3a·3b). In all cases, the metal centers show octahedral geometry coordinated to three chloride ligands and one S coordinated dimethylsulfoxide (DMSO-κS). The coordination sphere of the metal is completed by the pyrapyr molecule. Two different coordination modes are observed: (i) the DMSO-κS is opposite to the pyrimidinic N atom (IUPAC nomenclature is OC-6-31 denoted herein as trans); (ii) DMSO-κS is opposite to the pyrazolic N atom (IUPAC nomenclature is OC-6-41 denoted as cis). For Rh(III) the kinetic product (cis) yields the thermodynamic (trans) upon heating a solution of the kinetic product and both isomers have been X-ray characterized. Conversely for Ru(III), both kinetic and thermodynamic complexes have been obtained by using different procedures. Both isomers have been characterized by X-ray crystallography and the kinetic product does not yield the thermodynamic upon heating a solution of the former. Furthermore, the Ir(III) behaves differently, since both isomers are energetically equivalent and both isomers co-crystallize in the solid state. The kinetic/thermodynamic mechanism that yields the different isomers has been studied by using theoretical DFT calculations for each metal. Finally, two Ru(II) complexes (OC-6-N1)-[RuIICl2(DMSO-κS)2(pyrapyr)] (4a, N = 3 and 4b, N = 4) are also described and X-ray characterized. They were obtained as minor products during the synthesis of 2a.

Crystal structures of N6-modified-amino acid nucleobase analogs(III): adenine–valeric acid, adenine–hexanoic acid and adenine–gabapentine

Abstract: In this manuscript we report the synthesis and structural characterization of three amino acid adenine derivatives: N-(7H-purin-6-yl)-5-aminovaleric (N6-5AValAde) (1), N-(7H-purin-6-yl)-6-aminohexanoic (N6-6AHexAde) (2) and N-(7H-purin-6-yl)gabapentine (N6-GabapenAde) (4); and the hydrochloride form of 2, (3) In compound (1) with a neutral adenine ring and the chain arranged almost in an orthogonal position, the carboxylic groups interact with the N(7) and N(6)–H(6) of the neighbour molecule forming 1D supramolecular polymers It also establishes strong N(9)–H⋯N(3) interactions between the adenine rings leading to self-assembled dimers In the layered compound (2), the adenine also forms self-assembled dimers via double N(9)–H⋯N(3) interactions However, conversely to (1), the chain is arranged in the same plane of the ring facilitating the formation of coplanar self-assembled dimers via the Hoogsteen face In the hydrochloride form of N6-6AHexAde (compound 3) the adenine ring is protonated in N(1) which is hydrogen bonded to the chloride anion [N(1)–H⋯Cl = 2198 A] As with the neutral compound (1), the carboxylic group is bound to N(7) and the H–N(6) of a neighbour molecule and the double and strong [N(9)–H⋯N(3) = 2069 A] interaction between coplanar adenine rings is present A common feature of compounds (1)–(3) (linear amino acid), is the formation of adenine⋯carboxylic group interactions via the de Hoogsteen site of adenine, and also adenine⋯adenine self-association via N(9)–H⋯N(3) interactions In compound (4), that incorporates a gabapentine chain attached to the adenine ring, 3D packing is organized again with protonated carboxylate and N(7)/H–N(6) contacts: [O(19)–H⋯N(7) and O(18)⋯HN(6)] and a water molecule that holds 3 different molecules together by forming three O/N⋯H hydrogen bonds Again stacking interactions between the eclipsed pyrimidine rings in anti disposition [C(5)⋯C(2)/C(2)⋯C(5) of 3387 A] are observed Finally, we studied the noncovalent interactions observed in the solid state architecture using DFT calculations, and rationalized the interactions using molecular electrostatic potential surfaces and the quantum theory of “atoms-in-molecules” The aim of this study is to investigate the competition between homodimer formation by the Hoogsteen face of the adenine/adeninium, self-association of the carboxylic group, or the interaction of the carboxylic group with the adenine/adeninium cation

Metal removal from the secondary building unit of bio-MOF-1 by adenine N6-alkylation while retaining the overall 3D porous topology

Abstract: A novel approach to modify the SBU of the well-known bio-MOF-1 by reducing the nuclearity of the metal cluster while retaining the topology of the anionic 3D framework is reported. The resulting BioMOF is prone to accept H ions from the organic counterions providing a route to obtain neutral frameworks.

CH/π hydrogen bonds in crystals

Abstract: The nature and characteristics of the CH/π interaction are discussed by comparison with other weak molecular forces such as the CH/O and OH/π interaction. The CH/π interaction is a kind of hydrogen bond operating between a soft acid CH and a soft base π-system (double and triple bonds, C6 and C5 aromatic rings, heteroaromatics, convex surfaces of fullerenes and nanotubes). The consequences of CH/π hydrogen bonds in supramolecular chemistry are reviewed on grounds of recent crystallographic findings and database analyses. The topics include intramolecular interactions, crystal packing (organic and organometallic compounds), host/guest complexes (cavity-type inclusion compounds of cyclodextrins and synthetic macrocyclic hosts such as calixarenes, catenanes, rotaxanes and pseudorotaxanes), lattice-inclusion type clathrates (including liquid crystals, porphyrin derivatives, cyclopentadienyl compounds and C60 fullerenes), enantioselective clathrate formation, catalytic enantioface discriminating reactions and solid-state photoreaction. The implications of the CH/π concept for crystal engineering and drug design are evident.

Aromatic rings in chemical and biological recognition: energetics and structures.

Abstract: This review describes a multidimensional treatment of molecular recognition phenomena involving aromatic rings in chemical and biological systems. It summarizes new results reported since the appearance of an earlier review in 2003 in host-guest chemistry, biological affinity assays and biostructural analysis, data base mining in the Cambridge Structural Database (CSD) and the Protein Data Bank (PDB), and advanced computational studies. Topics addressed are arene-arene, perfluoroarene-arene, S⋅⋅⋅aromatic, cation-π, and anion-π interactions, as well as hydrogen bonding to π systems. The generated knowledge benefits, in particular, structure-based hit-to-lead development and lead optimization both in the pharmaceutical and in the crop protection industry. It equally facilitates the development of new advanced materials and supramolecular systems, and should inspire further utilization of interactions with aromatic rings to control the stereochemical outcome of synthetic transformations.

Anion receptor chemistry: highlights from 2010

Abstract: This critical review covers advances in anion complexation in the year 2010. The review covers both organic and inorganic systems and also highlights the applications to which anion receptors can be applied such as sensing, anion transport, control of molecular motion and gelation (179 references).