Magnetoelectric (ME) materials combine magnetic and electric polarizabilities in the same phase, offering a basis for developing high-density data storage and spintronic or low-consumption devices owing to the possibility of triggering one property with the other. Such applications require strong interaction between the constitutive properties, a criterion that is rarely met in classical inorganic ME materials at room temperature. We provide evidence of a strong ME coupling in a paramagnetic ferroelectric lanthanide coordination complex with magnetostrictive phenomenon. The properties of this molecular material suggest that it may be competitive with inorganic magnetoelectrics.

The molecular structure, vibrational spectra and photochemistry of 5-methylhydantoin (CHNO; 5-MH) were studied by matrix isolation infrared spectroscopy and theoretical calculations at the DFT(B3LYP)/6-311++G(d,p) theory level. The natural bond orbital (NBO) analysis approach was used to study in detail the electronic structure of the minimum energy structure of 5-MH, namely the specific characteristics of the σ and π electronic systems of the molecule and the stabilizing orbital interactions. UV irradiation of 5-MH isolated in argon matrix resulted in its photofragmentation through a single photochemical pathway, yielding isocyanic acid, ethanimine, and carbon monoxide, thus following a pattern already observed before for the parent hydantoin and 1-methylhydantoin molecules. The investigation of the thermal properties of 5-MH was undertaken by differential scanning calorimetry (DSC), polarized light thermal microscopy (PLTM) and Raman spectroscopy. Four different polymorphs of 5-MH were identified. The crystal structure of one of the polymorphs, for which it was possible to grow up suitable crystals, was determined by X-ray diffraction (XRD). Two of the additional polymorphs were characterized by powder XRD, which confirmed the molecules pack in different crystallographic arrangements.

The molecular structure and photochemistry of 5-thiosaccharyl-1-methyltetrazole (TSMT) were studied by means of matrix-isolation FTIR spectroscopy, X-ray crystallography, and theoretical calculations. The calculations predicted two conformers of TSMT that differ in energy by more than 15 kJ mol(-1). The infrared spectrum of TSMT isolated in solid argon was fully assigned on the basis of the spectrum calculated (O3LYP/6-311++G(3df,3pd)) for the most stable conformer. In the crystal, TSMT molecules were found to assume the same conformation as for the isolated molecule, with each molecule forming four hydrogen bonds with three neighboring molecules, leading to a network of TSMT oligomers. Upon UV (λ = 265 nm) irradiation of the matrix-isolated TSMT, two photodegradation pathways were observed, both arising from cleavage of the tetrazolyl ring. Pathway a involves cleavage of the N1-N2 and N3-N4 bonds with extrusion of N2, leading to photostable diazirine and thiocarbodiimide derivatives. The photostability of the photoproduced diazirine under the conditions used precluded its rearrangement to the nitrile imine, as reported for 5-phenyltetrazole by Bégué et al. ( J. Am. Chem. Soc. 2012 , 134 , 5339 ). Pathway b involves cleavage of the C5-N1 and N4-N3 bonds, leading to a thiocyanate and methyl azide, the latter undergoing subsequent fragmentation to give CNH.

Recent publications report in vitro activity of quinolone 3-esters against the bc1 protein complex of Plasmodium falciparum and the parasite. Docking studies performed in silico at the yeast Qo site established a key role for the 4-oxo and N-H groups in drug-target interactions. Thus, the possibility of 4-oxoquinoline/4-hydroxyquinoline tautomerism may impact in pharmacologic profiles and should be investigated. We describe the synthesis, structure, photochemistry, and activity against multidrug-resistant P. falciparum strain Dd2 of ethyl 4-oxo-7-methylquinoline-3-carboxylate (7Me-OQE) and ethyl 4-hydroxy-5-methylquinoline-3-carboxylate (5Me-HQE), obtained from diethyl 2-[((3-methylphenyl)amino)methylene]malonate. Theoretically (B3LYP/6-311++G(d,p)), 5Me-HQE and 7Me-OQE show clear preference for the hydroxyquinoline form. The difference between the lowest energy hydroxyquinoline and quinolone forms is 27 and 38 kJ mol(-1), for 5Me-HQE and 7Me-OQE, respectively. Calculations of aromaticity indexes show that in 5Me-HQE both rings are aromatic, while in the corresponding oxo tautomers the nitrogen-containing ring is essentially non-aromatic. The structure of monomeric 5Me-HQE was studied using matrix isolation coupled to FTIR spectroscopy. No traces of 4-oxoquinoline tautomers were found in the experimental IR spectra, revealing that the species present in the crystal, 5Me-HQE·HCl, was lost HCl upon sublimation but did not tautomerize. Continuous broadband irradiation (λ > 220 nm; 130 min) of the matrix led to only partial photodecomposition of 5Me-HQE (ca. 1/3).

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The conformational space of 5-acetic acid hydantoin {5AAH; [2-(2,5dioxoimidazolidin-4-yl)acetic acid]} was investigated by quantum chemical calculations performed at the DFT(B3LYP)/6-311++G(d,p) level of theory. A total of 13 conformers were located in the potential energy surface of the molecule, 6 of them bearing the carboxylic group in the cis arrangement (O=C-O-H dihedral equal to ~0º) and the other 7 possessing this group in the trans configuration (O=C-O-H dihedral equal to ~180º). The most stable conformer (cis-I) was trapped from the gas phase into a low temperature argon matrix (10 K), and its infrared spectrum was fully assigned, also with help of results of normal coordinates' analysis based on the DFT computed vibrational data. The electronic structure of this conformer was analyzed by using the Natural Bond Orbital (NBO) method.The investigation of the thermal properties of 5-AAH was undertaken by differential scanning calorimetry (DSC), polarized light thermal microscopy (PLTM) and Raman spectroscopy, allowing identification of five different polymorphs. Very interestingly, in the room temperature stable polymorph the molecular units of 5-AAH assume the geometry of the highest-energy conformer predicted by the calculations for the isolated molecule.

Saccharinate-tetrazolesTSand2MTSbind selectively to copper(ii). The resulting copper complexes have shown a huge increase in thein vitrocytotoxicity against hepatic carcinoma cells (HepG2) compared to the corresponding nontoxic free ligands.

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