Search results for "Inclusion complexe"
showing 10 items of 12 documents
[2]Catenanes and inclusion complexes derived from self-assembled rectangular PdII and PtII metallocycles
2012
New inclusion complexes and [2]catenanes were self-assembled from a fluorescent diazapyrenium based ligand, a PdII or PtII complex, and cyclic or acyclic electron rich aromatic guests in aqueous and organic media. The molecular rectangles display a π-deficient cavity suitable to incorporate π-donor aromatic systems. The inclusion complexes between the metallocycles and phenylenic (2a,b) and naphthalenic (3a,b–5a,b) derivatives were studied by NMR, UV-vis and fluorescence spectroscopy. The crystal structure of (3b) ⊂ 1a·6PF(6) confirmed the insertion of the guest into the cavity of the metallocycle. Following the same self-assembly strategy, the use of polyethers 6,7 as π-donors resulted in …
Cascade complex formation by phosphate in the cobalt(II)/[30]aneN10 anaerobic system
1993
Abstract The interaction of phosphate with the mono- and binuclear cobalt(II) complexes of [30]aneN 10 (1,4,7,10,13,16,19,22,25,28-decaazacyclotriacontane) has been studied by potentiometry in 0.15 mol dm −3 NaClO 4 solution at 298.15 K under anaerobic conditions. The stable species [CoH 2 ([30]aneN 10 )PO 4 ] + , [CoH 4 ([30]aneN 10 )PO 4 ] 3+ , [Co 2 H([30]aneN 10 )PO 4 ] 2+ , [Co 2 H 2 ([30]aneN 10 )PO 4 ] 3+ and [Co 2 H 3 ([30]aneN 10 )PO 4 ] 4+ , where the phosphate anion is directly bound to the metal ions or acts as a second sphere ligand, are formed and their stability constants have been determined. The results obtained allowed for the selection of suitable conditions for the study…
Structural and physicochemical characterization of the inclusion complexes of cyclomaltooligosaccharides (cyclodextrins) with melatonin
2002
The stoichiometry, geometry, stability, and solubility of the inclusion complexes of melatonin (MLT) with native cyclomaltooligosaccharides (α-, β- or γ-cyclodextrins, CDs) are determined experimentally by high-resolution NMR spectroscopy, calorimetric and solubility measurements, and mass spectrometry. The observed differences are discussed in terms of molecular recognition expression of the host-guest (h-g) interactions within the hydrophobic CDs cavities of different size. The 1:1 h-g stoichiometry in water solution prevails at low CD concentrations; the trend to form higher order associations is observed at increasing CD concentrations. The stability order β-CD>γ-CD>α-CD for the c…
Conformational changes in Cmethyl-resorcinarene pyridine N -oxide inclusion complexes in the solid state
2016
Aromatic N-oxides interact with Cmethyl-resorcinarene resulting in marked changes in the conformation of the host resorcinarene. In the solid state, 2- and 3-methylpyridine N-oxides form pseudo-capsular 2 : 2 endo host-guest complexes with Cmethyl-resorcinarene stabilized by C-H⋯π interactions. The Cmethyl-resorcinarene·2-methylpyridine N-oxide complex has a C4v crown conformation, while the Cmethyl-resorcinarene·3-methylpyridine N-oxide complex has a slightly open C2v boat conformation. On the contrary, other para-substituted and benzo-fused pyridine N-oxides form only exo complexes with Cmethyl-resorcinarene. In the exo complexes, the asymmetry of the guest, conformational flexibility and…
Selective recognition of small hydrogen bond acceptors by a calix[6]arene-based molecular container
2019
Selective molecular recognition is of primary importance for applications such as sensing and separation of chemicals. This work describes the host-guest and crystallisation properties of a penta-carbamated calix[6]arene designed as a molecular container with a H-donating recognition group directed towards the heart of the cavity. As demonstrated by NMR spectroscopy and X-ray diffraction studies, this macrocyclic receptor can selectively recognise small H-bond acceptors through one or two hydrogen bonds, the guests nesting inside the polyaromatic cavity surrounded by eleven bulky tert-butyl groups.
Inclusion complexes of cyclomaltooligosaccharides (cyclodextrins) with melatonin in solid phase
2005
Fourier transform infrared spectrometry (FT-IR) and X-Ray diffraction (XRD) investigations were carried out on MLT plus α-, β- and γ-CD physical mixtures and lyophilized or crystalline MLT/α-, β-, γ-CD complexes. Inclusion complexes formation between MLT and cyclodextrins in solid phase has been emphasized by the significant differences between IR and XRD spectra of physical mixtures with respect to those of the complexes. The structure of MLT CDs complexes in the solid state as well as the biochemical and pharmaceutical implications are discussed.
Cyclotriveratrylene-Containing Porphyrins
2016
International audience; The C-3-symmetric cyclotriveratrylene (CTV) was covalently bonded via click chemistry to 1, 2, 3, and 6 zinc(II) porphyrin units to various host for C-60. The binding constants, Ka, were measured from the quenching of the porphyrin fluorescence by C-60. These constants vary between 400 and 4000 M-1 and are considered weak. Computer modeling demonstrated that the zinc(II) porphyrin units, [Zn], exhibit a strong tendency to occupy the CTV cavity, hence blocking the access for C-60 to land on this site. Instead, the pincer of the type [Zn]-[Zn] and in one case [Zn]-CTV, were found to be the most probable geometry to promote host-guest associations in these systems.
Badanie właściwości inkluzyjnych p-tert-butylokaliksarenów metodą inwersyjnej chromatografii gazowej
2007
Metodą QSRR scharakteryzowano właściwości inkluzyjne p-tert-butylokaliksarenów o 4, 6 i 8 merach w cyklu oraz ich octanów, wykorzystując do tego celu inwersyjną chromatografię gazową. W badaniach zastosowano przy tym dwa szeregi homologiczne solutów - alkohole alifatyczne oraz benzen i jego homologi. Stwierdzono, że zdolności inkluzyjne w znacznym stopniu zależą od wymiarów luki molekularnej cyklomeru. Zamiana w kaliksarenach grup wodorotlenowych na octanowe nie wywiera natomiast istotnego wpływu na możliwości tworzenia kompleksów typu gość-gospodarz. Wyniki uzyskane metodą QSRR potwierdzono wyznaczonymi wartościami indeksów Kovátsa.
Badanie metodą inwersyjnej chromatografii gazowej wpływu wielkości podstawnika na właściwości inkluzyjne kaliksarenów
2009
Badano wpływ wielkości alifatycznego podstawnika na zdolności inkluzyjne kaliksarenów {kaliks[4]arenu(K4), p-izopropylokaliks[4]arenu (IPK4) i p-tert-butylokaliks[4]arenu (TBK4)}. Oceny wpływu dokonywano za pomocą metody QSRR przy użyciu inwersyjnej chromatografii gazowej. W charakterze solutów użyto szeregu alifatycznych alkoholi, homologów benzenu i homologów pirydyny. Na podstawie indeksów retencji Kovatsa i wykresów zależności właściwej objętości retencji od temperatury wrzenia [Vg=f(Tw)] stwierdzono, że tylko podstawione kaliksareny wykazują właściwości inkluzyjne w stosunku do niższych alkoholi.
Complexation of phosphine ligands with peracetylated β-cyclodextrin in supercritical carbon dioxide: Effect of temperature and cosolvent on the equil…
2009
Abstract The interaction between peracetylated-β-cyclodextrin and tert-butyl and adamantyl functionalized triphenylphosphine derivatives was studied in supercritical carbon dioxide (scCO 2 ) based solvent media by UV–vis spectroscopy. The equilibrium constant for a 1:1 complexation reaction was obtained from titration spectra both in pure carbon dioxide and in the presence of methanol as a cosolvent in the temperature range 308–323 K to estimate the internal energy and entropy of the inclusion equilibrium. The values of the equilibrium constants were found significantly smaller than those obtained in aqueous solution with analogous phosphines and substantially independent of the nature of t…