Search results for "Molecular chemistry"

Nano-sized I12L6 Molecular Capsules Based on the [N⋅⋅⋅I+⋅⋅⋅N] Halogen Bond

2017

Summary Self-assembly of pre-organized subunits with a concave overall shape is an effective strategy for the synthesis of supramolecular capsules. We report the synthesis of a cavitand-based hexameric capsule held together solely by 12 robust [N⋅⋅⋅I + ⋅⋅⋅N] halogen bonds and its characterization in solution and in the gas phase via 1 H NMR spectroscopy, diffusion-ordered nuclear magnetic resonance spectroscopy (DOSY), and electrospray ionization mass spectrometry. The [N⋅⋅⋅I + ⋅⋅⋅N] halogen-bonded hexameric capsule was efficiently synthesized from the isolobal metallosupramolecular Ag + capsule by application of the [N⋅⋅⋅Ag + ⋅⋅⋅N] → [N⋅⋅⋅I + ⋅⋅⋅N] cation-exchange reaction.

Surprising solvent-induced structural rearrangements in large [N⋯I+⋯N] halogen-bonded supramolecular capsules

2018

Coordinative halogen bonds have recently gained interest for the assembly of supramolecular capsules. Ion mobility-mass spectrometry and theoretical calculations now reveal the well-defined gas-phase structures of dimeric and hexameric [N...I+...N] halogen-bonded capsules with counterions located inside their cavities as guests. The solution reactivity of the large hexameric capsule shows the intriguing solvent-dependent equilibrium between the hexamer and an unprecedented pentameric [N...I+...N] halogen-bonded capsule, when the solvent is changed from chloroform to dichloromethane. The intrinsic flexibility of the cavitands enables this novel structure to adopt a pseudo-trigonal bipyramida…

Novel supramolecular affinity materials based on (−)-isosteviol as molecular templates

2013

The readily available ex-chiral-pool building block (−)-isosteviol was combined with the C3-symmetric platforms hexahydroxytriphenylene and hexaaminotriptycene providing large and rigid molecular architectures. Because of the persistent cavities these scaffolds are very potent supramolecular affinity materials for head space analysis by quartz crystal microbalances. The scaffolds serve in particular as templates for tracing air-borne arenes at low concentration. The affinities of the synthesized materials towards different air-borne arenes were determined by 200 MHz quartz crystal microbalances.

The effect of the cation p-surface area on the 3D organization and catalytic ability of imidazolium-based ionic liquids

2011

The dichotomic nature of ionic liquids (ILs, simple solvents or supramolecular fluids) induced us to carry out a structural investigation of some mono-and dicationic ionic liquids using 1D and 2D NMR, resonance light scattering, and UV/Vis spectroscopy. Ionic liquids with different cation π-surface areas were used, namely [bmim][NTf2], [Bzmim][NTf 2], [Bzbim][NTf2], [p-Xyl-(bim)2][NTf 2]2, and [m-Xyl-(bim)2][NTf2] 2 [bmim = 1-butyl-3-methylimidazolium, Bzmim = 1-benzyl-3- methylimidazolium, Bzbim = 1-benzyl-3-butylimidazolium, NTf2 = bis(trifluoromethansulfonyl)imide]. In order to verify to what extent the structural investigation, coupled with the determination of solvent parameters, could…

Ion pair recognition by ditopic crown ether based bis-urea and uranyl salophen receptors

2016

N-Cinnamoyltetraketide Derivatives from the Leaves of Toussaintia orientalis

2015

Seven N-cinnamoyltetraketides (1−7), including the new Ztoussaintine E (2), toussaintine F (6), and toussaintine G (7), were isolated from the methanol extract of the leaves of Toussaintia orientalis using column chromatography and HPLC. The configurations of E-toussaintine E (1) and toussaintines A (3) and D (5) are revised based on single-crystal X-ray diffraction data from racemic crystals. Both the crude methanol extract and the isolated constituents exhibit antimycobacterial activities (MIC 83.3−107.7 μM) against the H37Rv strain of Mycobacterium tuberculosis. Compounds 1, 3, 4, and 5 are cytotoxic (ED50 15.3−105.7 μM) against the MDA-MB-231 triple negative aggressive breast cancer cel…

Anion Responsive Molecular Switch Based on a Doubly‐Strapped Calix[4]pyrrole

2022

A calix[4]pyrrole receptor bearing two proximally meso - meso linking isophthaloyl straps displays open and closed states depending on the calix[4]pyrrole conformation. In the crystal structures and in non-polar solvent, the calix[4]pyrrole adopts open 1,3-alternate conformation with straps on the sides. Anion binding triggers a closed state of the receptor providing two types of interactions with an aromatic benzoate guest: hydrogen bonds from the pyrrolic groups and π ··· π interactions from the phenyl groups of the straps. Slow exchange dynamics was observed on the NMR timescale indicating that benzoate, acetate and chloride anions, which bind with relatively low affinity get kinetically…

In Vitro Modulation of P-Glycoprotein Activity by Euphorbia intisy Essential Oil on Acute Myeloid Leukemia Cell Line HL-60R

2021

Euphorbia species have a large spectrum of traditional medicinal uses. We tested the biological activities of the essential oil (EO) of Euphorbia intisy Drake in an acquired multidrug resistance leukemia model to assess whether the EO obtained by hydrodistillation of stems was able to reverse the resistant phenotype. HL-60R cell lines are characterized by the overexpression of P-glycoprotein (P-gp), inhibitors of apoptosis proteins (IAPs) and constitutive expression of NF-κB. EO chemical composition was determined by GC/MS analysis

Ruta chalepensis L. (Rutaceae) leaf extract: chemical composition, antioxidant and hypoglicaemic activities.

2017

Ruta chalepensis L. (Rutaceae) leaf extract was investigated for its chemical profile and antioxidant and hypoglycaemic properties. The antioxidant effects were investigated by 2,2-diphenyl-1-picrylhydrazyl (DPPH), Chi-carotene bleaching, and metal chelating activity assays. The carbohydrate-hydrolysing enzymes inhibition assay was used to test the hypoglycaemic potential. R. chalepensis showed a high content of hesperidin and rutin with values of 591.9 and 266.7 mg/g dry extract, respectively. The extract exhibited a promising protection of lipid peroxidation (IC50 value of 16.9 mu g/mL) and inhibited both alpha-amylase and alpha-glucosidase enzymes in a concentration-dependent manner. The…

Comparative chemical composition and bioactivity of leaves essential oils from nine Sicilian accessions of Myrtus communis L.

2019

In this study, the essential oils obtained from the leaves of Myrtus communis L. stored in a collection orchard located at the experimental station ‘Orleans’ of the Department of Agricultural and Forest Sciences of the University of Palermo (Italy) were investigated. The essential oils, analysed by gas chromatography–mass spectrometry, revealed the presence of α-pinene, 1,8-cineole, linalool, limonene and myrtenyl acetate as dominant constituents. The neuroprotective effects of M. communis essential oils were investigated by analysing the antioxidant properties and cholinesterases (acetylcholinesterase, AChE, and butyrylcholinesterase, BChE) inhibitory activity. Essential oils from Scopello…