Jeroni Morey

Colorimetric detection of chemical warfare simulants

Two simple chromogenic indicators (4) and (5), containing different supernucleophilic moieties, have been synthesized. Upon phosphorylation with two chemical warfare agent (CWA) simulants, a hypsochromic shift of approximately 50 nm is observed in an NaOH–DMSO solution. The oximate supernucleophile was found to be a better supernucleophile than the hydrazone moiety. Two X-ray crystal structures were obtained from unexpected synthetic side products obtained in this study. These will also be discussed.

Squaramido-based receptors: Molecular recognition of carboxylate anions in highly competitive media

Abstract A new series of artificial receptors for binding carboxylates has been developed. The receptors are based on the hydrogen bonding abilities of secondary squaramides as binding subunits. The data reveal the formation of 1:1 complexes in highly competitive media. Using convenient spacers, receptors for di- and tri-carboxylates that incorporate two and three squaramide subunits have been prepared. The complexes are characterized by nmr and, when possible, by FAB spectral analysis.

Squaramide as a binding unit in molecular recognition

Abstract Urea and squaramide are used as building blocks of powerful hosts which are involved in the molecular recognition of quaternary ammonium guests. Complexes of urea and squaramide with ammonium cations were studied using both high level MP2/6-311+G** ab initio and molecular interaction potential with polarization and MEP calculations, in order to explore the physical nature of the interactions. The same procedure was applied to ammonium complexes with water and benzene as prototype models of crown ethers and calixarenes. Our findings reveal that either urea or squaramide are better binding units for the recognition of ammonium cations than water or benzene.

Thermodynamic characterization of the squaramide–carboxylate interaction in squaramide receptors

Abstract The thermodynamic characterization of squaramides is described. This fundamental information shows that the association in chloroform or DMSO is mainly exothermic. In contrast, in MeOH the equilibrium is endothermic and is entropically driven. The data shows the influence of a squaramide ring alone, modified or combined with tetraalkylammonium groups as the binding subunit for molecular recognition.

Binding of caffeine by a synthetic co-receptor

A new co-receptor macrobicyclophane for binding caffeine has been developed. The co-receptor binding sites are based on the hydrogen bonding abilities of secondary amides. 1H NMR titrations demonstrate recognition of caffeine by formation of a 2:1 complex in CDCl3.

Solid state redox chemistry of hydroquinones and quinones

Abstract Solid state ceric ammonium nitrate (CAN) oxidation of hydroquinones to the corresponding quinones, gives best results when operating with ultrasonic irradiation. Nitrogen dioxide plays a key role in these “solid-solid” oxidations. The oxidation of hydroquinones to quinones can also be achieved in a unique “solid-solid-solid” reaction, i.e., by using a limited amount of CAN in the presence of a full equivalent of a solid cooxidant such as KBrO3. Reduction of quinones with sodium dithionite in the solid state gives rise to the corresponding highly colored quinhydrones and, eventually, to hydroquinones.

Influence of remote intramolecular hydrogen bonds on the thermodynamics of molecular recognition of cis-1,3,5-cyclohexanetricar☐ylic acid

Abstract Variable temperature binding studies and isothermal titration microcalorimetry were used to probe the thermodynamics of molecular recognition of cis -1,3,5-cyclohexanetricar☐ylic acid by tripodal hosts. Remote intramolecular hydrogen bonds, used to restrict conformationally one of the hosts, exhibit a strong influence on the thermodynamic functions for the binding process ΔH and ΔS, with little effect on ΔG. This suggests that the conformational lock imposed by the intramolecular hydrogen bonds organizes the receptor in a conformation that is not optimal for the binding of the triacid.

Highly efficient coordination of Hg2+ and Pb2+ metals in water with squaramide-coated Fe3O4 nanoparticles

The synthesis and binding properties of squaramide-coated Fe3O4 nanoparticles upon coordination with heavy metals in water are described. The nanoparticles feature selective binding towards Hg2+ and Pb2+ cations in the presence of other interfering heavy metals. The binding affinity of the nanoparticles is especially high for mercury and lead cations. The mode of action of the squaramide-coated nanoparticles differs significantly from that of previously reported nanoparticles used as Hg2+ scavengers. The selective Hg2+ sequestering capabilities displayed by the squaramide-coated nanoparticles are related to the formation of organomercury compounds. The solid state structure of the organomercury complex obtained by treatment of a di-squaramide with Hg2+ salts is described, demonstrating the mercuriation of the aryl moiety of dopamine.

Antifolate-modified iron oxide nanoparticles for targeted cancer therapy: inclusion vs. covalent union

In this work four different iron oxide nanoparticles for the delivery of antitumoral drugs into cancer cells were synthesized and characterized. The antifolates raltitrexed, pemetrexed and methotrexate were bound to iron oxide nanoparticles by two different methods: covalent bonding or non-covalent interactions, such as electrostatic and H-bonding. For the covalent bonding of antifolates to the surface of nanoparticles an appropriate linker (3-aminopropyltriethoxysilane) was used, while the non-covalent interaction was achieved using nanoparticles functionalized in one step with squaramides and meso-2,3-dimercaptosuccinic acid. To evaluate the efficacy of the antifolate-derivatized nanoparticles, their cytotoxicity was assayed in A549 human lung adenocarcinoma cells. Only administration of the covalent antifolate-functionalized nanoparticles strongly inhibited the viability of these cancer cells, whereas the delivery of antifolates bound to nanoparticles through non-covalent interactions did not exhibit significant cytotoxic effects. The present results suggest that covalent antifolate-functionalized nanoparticles could be a potential delivery system for certain cancer cells.

The generation of C,O,O-trilithiated derivatives of dihydric phenols

Abstract Halogenated dihydric phenols (hydroquinones and resorcinols) undergo halogen metal exchange with nBuLi/TMEDA/THF or ether (inverse addition) under sonication, thereby generating a C,O,O-trilithiated species which can be trapped with electrophiles.