Search results for "Molecular chemistry"

Azacoronands and Azacyclophanes

2012

Azacycloalkanes and azacyclophanes are among the first macrocyclic ligands developed in the field of supramolecular chemistry. Since they are polyamines, they show dual nature in the coordination of both metal cations, when they are in the free-base form, and anionic species, when they are protonated. As a matter of fact, they played a key role in the birth of macrocyclic chemistry of transition metal complexes and anion coordination chemistry. Furthermore, azacyclophanes fostered also the birth of apolar complexation in aqueous solution, since their aromatic units act as binding sites for apolar substrates. Keywords: azacycloalkanes; azacyclophanes; metal complexes; anion complexes; apolar…

Supramolecular assemblies of phenyl-pyridyl-triazolopyridine and β-cyclodextrin as sensor of divalent cations in aqueous solution

2014

The chemosensor 3-phenyl-7-(pyrid-2-yl)-[1,2,3]triazolo[1,5-a]pyridine (PhPTP) used in combination with two different cyclodextrins, enable its solubilization and stabilization in aqueous solution. The behavior of the inclusion complex, and its binding ability in both cyclodextrins were investigated by means of absorption and fluorescence spectroscopy. The best results were obtained for PhPTP-DMβCD assembly, and its orientation in the DMβCD nano cavity was obtained by 2D-NMR. This inclusion geometry was confirmed by docking studies. The binary complex was proved as chemosensor upon the presence of different divalent cations in aqueous solutions. The PhPTP-DMβCD system, displays a high sensi…

New phenolics, cytotoxicity and chemosystematic significance of Atriplex semibaccata

2019

Abstract The chemical characterization of the 70% hydromethanolic extract of Atriplex semibaccata (family: Chenopodiaceae) afforded a new methoxylated flavonol triglycoside, atrisemibaccatoside A (1), and a new lignanamide, (N-[(E)-m-hydroxycinnamoyl]tyramine (7), as well as, five known flavonols (2–6) and two lignanamides (8–9). The structures of the isolated compounds were established depending upon LR&HR-FAB-MS, 1D and 2D NMR spectroscopic analyses. The cytotoxic activity of the isolated compounds (1–4, and 7–9) was investigated. Compounds 7, 8 and 9 weakly inhibited the proliferation of leukemia CCRF-CEM cells with IC50 values of 78.5, 46.3, and 71.2 μg/ml, respectively, and exhibited n…

ChemInform Abstract: Cryptand-Like Anion Receptors

2010

The design of supramolecular hosts for anions began with simple diaza bicycles, named katapinands, and has evolved over the last 40 years to a number of elegantly designed receptors capable of binding many different anions. About the same time the term cryptand appeared in reference to another bicyclic compound that was selective for alkaline-earth ions. Since the first report these simple bicycles, a vast arena of hosts has appeared, including acyclic, monocyclic, and other multicyclic supramolecular receptors. Studies of these systems have revealed considerable information about anion coordination chemistry, including the fact that many of these complexes mimic their transition-metal coro…

Cryptand-like anion receptors

2010

The design of supramolecular hosts for anions began with simple diaza bicycles, named katapinands, and has evolved over the last 40 years to a number of elegantly designed receptors capable of binding many different anions. About the same time the term cryptand appeared in reference to another bicyclic compound that was selective for alkaline-earth ions. Since the first report these simple bicycles, a vast arena of hosts has appeared, including acyclic, monocyclic, and other multicyclic supramolecular receptors. Studies of these systems have revealed considerable information about anion coordination chemistry, including the fact that many of these complexes mimic their transition-metal coro…

ChemInform Abstract: Electrical Conductive Coordination Polymers

2012

Coordination polymers are currently one of the hottest topics in Inorganic and Supramolecular Chemistry. This critical review summarizes the current state-of-the-art on electrical conductive coordination polymers (CPs), also named metal–organic frameworks (MOFs). The data were collected following two sort criteria of the CPs structure: dimensionality and bridging ligands (151 references).

Triterpene saponins from the roots of Bupleurum spinosum Gouan

2020

Abstract Three previously undescribed triterpene saponins, and four known ones, were isolated from the EtOH/H2O extract of the roots of Bupleurum spinosum. Their structures were characterized using spectroscopic techniques including 1D and 2D NMR (1H, 13C, COSY, TOCSY, ROESY, HSQC, and HMBC) experiments and mass spectrometry as 3-O-β-D-glucopyranosyl-(1→6)-[β-D-glucopyranosyl-(1→2)]-[α-L-rhamnopyranosyl-(1→4)]-β-D-glucopyranosyl-3β,16β,23,28-tetrahydroxyolean-12-ene, 3-O-β-D-glucopyranosyl-(1→6)-[β-D-glucopyranosyl-(1→2)]-[α-L-rhamnopyranosyl-(1→4)]-β-D-glucopyranosyl-3β,16β,28-trihydroxy-23-oxoolean-12-ene, 3-O-β-D-glucopyranosyl-(1→6)-[α-L-rhamnopyranosyl(1→4)]-β-D-glucopyranosyl-3β,16β,2…

Makrobicyclische Endorezeptoren: Synthese, Kristallstruktur und Einschluß organischer Gastmoleküle

1992

Macrobicyclic Endoreceptors: Synthesis, Crystal Structure, and Inclusion of Organic Guests The macrobicyclic ligand 2 is synthesized in a one-step cyclization procedure. According to an X-ray structure analysis three dichloromethane guest molecules are included inside the cavity, whereas water and methanol are found outside the cavity. The rigid endo preorganization of the nitrogen donors allows the complexation of three 2,9-disubstituted 1,10-phenanthrolines inside the cavity.

Cover Feature: Mannose-Decorated Multicomponent Supramolecular Polymers Trigger Effective Uptake into Antigen-Presenting Cells (ChemBioChem 9/2018)

2018

Understanding Noncovalent Interactions of Small Molecules with Carbon Nanotubes

2017

We combine experimental methods, density functional theory (DFT) calculations, and molecular dynamics (MD) simulations in the quantitative analysis of noncovalent interactions between (6,5)-enriched single-walled carbon nanotubes (SWNTs), as hosts, and a set of pyrene derivatives with different electronic properties and surface areas, as guests. The experiments and calculations were carried out in two solvents with markedly different polarities, namely 1,1',2,2'-tetrachloroethane (TCE) and N,N-dimethylformamide (DMF). Our results show that dispersion forces govern the supramolecular association of small molecules with (6,5)-SWNTs, with negligible contributions from ground-state charge-trans…