Search

Four new halogen-bonded cocrystals of biological methylxanthines, named caffeine, theophylline and theobromine, have been prepared with 1,4-diiodotetrafluorobenzene as a halogen bond donor by mechanochemical and solution processes. For theophylline, N⋯I and N⋯O interactions were observed, while for caffeine and theobromine, only N⋯I was detected. The solids were characterized by PXRD, SC-XRD, FTIR and thermal methods (TGA-DSC analyses). In addition, the solid-state photoluminescence properties of the methylxanthines and their respective cocrystals have been studied and quantum chemistry calculations have been performed to rationalise and understand the electronic and optical properties of all compounds. This work provides a triad of natural methylxanthines capable of forming halogen-bonded multicomponent systems that can give rise to a cocrystal-to-crystal transformation with off-on luminescence activation.

Chemical-based interventions are mostly used to control insects that are harmful to human health and agriculture or that simply cause a nuisance. An overreliance on these insecticides however raises concerns for the environment, human health, and the development of resistance, not only in the target species. As such, there is a critical need for the development of novel nonchemical technologies to control insects. Electrocution traps using UV light as an attractant are one classical nonchemical approach to insect control but lack the specificity necessary to target only pest insects and to avoid harmless or beneficial species. Here we review the fundamental physics behind electric fields (EFs) and place them in context with electromagnetic fields more broadly. We then focus on how novel uses of strong EFs, some of which are being piloted in the field and laboratory, have the potential to repel, capture, or kill (electrocute) insects without the negative side effects of other classical approaches. As EF-insect science remains in its infancy, we provide recommendations for future areas of research in EF-insect science.

The application of halogen bonding in pharmaceutical chemistry remains a challenge. In this work, novel halogen-bonded cocrystals based on azole antifungal active pharmaceutical ingredients (APIs) and the ditopic molecule 1,4-diiodotetrafluorobenzene are reported. Their crystal structural features, spectroscopic properties, and thermal stability were studied. The components are bound through I···N from the triazole moieties present in all of the compounds. The molecular electrostatic potential (MEP) surfaces and quantum theory of atoms in molecules (QTAIM) calculations are used to rationalize the presence of hydrogen and halogen bonds in the resulting structures and their energetic analysis. The relative halogen bond ability of the different groups of voriconazole, fluconazole, and itraconazole was analyzed using MEP surfaces, demonstrating this approach to be an interesting tool to predict halogen-bonding preferences.

A series of four novel heteroleptic Cu(I) complexes, bearing bis(1H-indazol-1-yl)methane analogues as N,N ligands and DPEPhos as the P,P ligand, were synthesised in high yields under mild conditions and characterised by spectroscopic and spectrometric techniques. In addition, the position of the carboxymethyl substituent in the complexes and its effect on the electrochemical and photophysical behaviour was evaluated. As expected, the homoleptic copper (I) complexes with the N,N ligands showed air instability. In contrast, the obtained heteroleptic complexes were air- and water-stable in solid and solution. All complexes displayed green-yellow luminescence in CH2Cl2 at room temperature due to ligand-centred (LC) phosphorescence in the case of the Cu(I) complex with an unsubstituted N,N ligand and metal-to-ligand charge transfer (MLCT) phosphorescence for the carboxymethyl-substituted complexes. Interestingly, proper substitution of the bis(1H-indazol-1-yl)methane ligand enabled the achievement of a remarkable luminescent yield (2.5%) in solution, showcasing the great potential of this novel class of copper(I) complexes for potential applications in luminescent devices and/or photocatalysis.

This contribution describes an updated synthetic route along with full characterization of [{CpFe}2-p-Ph’] with p-Ph’: p-Bis{2,3,4,5tetramethylcyclopentadienyl}benzene). The complex reported here was characterized by 1H and 13C NMR, elemental analysis, the X-ray crystal structure, and Mössbauer spectroscopy. From the crystallographic analysis, it was found that both {CpFe} fragments are coordinated to opposite sites of the p-Ph’ ligand. In addition, the analysis through of 1H and 13C NMR spectroscopy, confirm that the synthesis and yield of just one isomer of this compound.

Two novel organic-inorganic decavanadate materials with protonated amines were prepared from acidified aqueous solution and characterized by single crystal X-Ray diffraction, thermogravimetric analysis and IR spectroscopy. (C6N2H9)4[H2V10O28]·4H2O (I) and (C7H9NF)4[H2V10O28]·2H2O (II), were isolated in single-crystal form. For both compounds, the crystal packing is governed by the formation of various non-covalent intermolecular forces between decavanadate anions, organic cations and water molecules. For both compounds, Hirshfeld surface analysis and two-dimensional fingerprint plots indicate that the most important contributions to in the crystal packing for both compounds are from O⋅⋅⋅H/H⋅⋅⋅O and H⋅⋅⋅H bonds. Furthermore, topological study of weak non-covalent interactions properties was theoretically carried out using DFT. The determined HOMO and LUMO levels were to estimate the charge transfer within the structure. The photoluminescence properties and UV–Vis absorption spectra have also been investigated. Both (I) and (II) possess photoluminescence properties and produce blue and green emissions, respectively, upon irradiation with violet light.

Six new multicomponent solids of 9-ethyladenine and oxalic acid have been detected and characterized. The salt screening has been performed by mechanochemical and solvent crystallization processes. Single crystals of the anhydrous salts in 1:1 and 2:1 nucleobase:coformer molar ratio were obtained by solution crystallization and elucidated by single-crystal X-ray analysis. The supramolecular interactions observed in these solids have been studied using density functional theory (DFT) calculations and characterized by the quantum theory of “atoms in molecules” (QTAIM) and the noncovalent interaction plot (NCIPlot) index methods. The energies of the H-bonding networks observed in the solid state of the anhydrous salts in 1:1 and 2:1 nucleobase:coformer are reported, disclosing the strong nature of the charge assisted NH···O hydrogen bonds and also the relative importance of ancillary C–H··O H-bonds.