Search results for "Alix"
showing 10 items of 505 documents
Complexation of M3+Lanthanide Cations by Calix[4]arene-CMPO Ligands: A Molecular Dynamics Study in Methanol Solution and at a Water/Chloroform Interf…
2000
Abstract We report a molecular dynamics study on the 1:1 M3+ lanthanide (La3+, Eu3+ and Yb3+) inclusion complexes of an important extractant molecule L: a calix[4]arene-tetraalkyl ether substituted at the wide rim by four NH-C(O)-CH2-P(O)Ph2 arms. The M(NO3)3 and MCl3 complexes of L are compared in methanol solution and at a water / chloroform interface. In the different environments the coordination sphere of M3+ involves the four phosphoryl oxygens and three to four loosely bound carbonyl oxygens of the CMPO-like arms. Based on free energy simulations, we address the question of ion binding selectivity in pure liquid phases and at the liquid-liquid interface where L and the complexes are …
Honeybees affect floral microbiome composition in a central food source for wild pollinators in boreal ecosystems
2021
AbstractBasic knowledge on dispersal of microbes in pollinator networks is essential for plant, insect, and microbial ecology. Thorough understanding of the ecological consequences of honeybee farming on these complex plant–pollinator–microbe interactions is a prerequisite for sustainable honeybee keeping. Most research on plant–pollinator–microbe interactions have focused on temperate agricultural systems. Therefore, information on a wild plant that is a seasonal bottleneck for pollinators in cold climate such as Salix phylicifolia is of specific importance. We investigated how floral visitation by insects influences the community structure of bacteria and fungi in Salix phylicifolia inflo…
Calix[4]arene-functionalized naphthalene and perylene imide dyes.
2002
[reaction: see text] Calix[4]arenes bearing one, two, or four 1,8-naphthyl imide groups at the wide rim and bis-calix[4]arenes connected via perylene-bisimide dye spacers have been synthesized. The low-temperature NMR spectrum of the tetranaphthylimide suggests, in agreement with a crystal structure, a C2-symmetrical pinched cone conformation stabilized via face-to-face pi-pi interactions between opposite naphthylimide groups. UV-vis and fluorescence studies have been carried out for the perylene bis-calix[4]arene dyes.
Intraspecific Differences in Spectral Reflectance Curves as Indicators of Reduced Vitality in High-Arctic Plants
2017
Remote sensing is a suitable candidate for monitoring rapid changes in Polar regions, offering high-resolution spectral, spatial and radiometric data. This paper focuses on the spectral properties of dominant plant species acquired during the first week of August 2015. Twenty-eight plots were selected, which could easily be identified in the field as well as on RapidEye satellite imagery. Spectral measurements of individual species were acquired, and heavy metal contamination stress factors were measured contemporaneously. As a result, a unique spectral library of dominant plant species, heavy metal concentrations and damage ratios were achieved with an indication that species-specific chan…
Extraction of lanthanides and actinides by a magnetically assisted chemical separation technique based on CMPO-calix[4]arenes
2001
A novel particulate system carrying CMPO ligands pre-organised on a calixarene scaffold has been synthesised and demonstrated to extract Eu3+, Am3+ and Ce3+ at high efficiency from simulated nuclear waste streams.
Biogas production and saccharification of Salix pretreated at different steam explosion conditions.
2011
Abstract Different steam explosion conditions were applied to Salix chips and the effect of this pretreatment was evaluated by running both enzymatic hydrolysis and biogas tests. Total enzymatic release of glucose and xylose increased with pretreatment harshness, with maximum values being obtained after pretreatment for 10 min at 210 °C. Harsher pretreatment conditions did not increase glucose release, led to degradation of xylose and to formation of furfurals. Samples pretreated at 220 and 230 °C initially showed low production of biogas, probably because of inhibitors produced during the pretreatment, but the microbial community was able to adapt and showed high final biogas production. I…
Unexpected Conformational Behaviour of a Diphosphate Derived from a Spherand-Type Calixarene
2005
The spherand-type calixarene 2a, which consists of three diphenol units linked by methylene bridges, was treated with phosphorus pentachloride and then with water. A C1-symmetrical conformation was found for the resulting bisphosphate 7 in the crystalline state by X-ray analysis, with an anti orientation of the phosphoryl groups. MM3 calculations lead to a nearly identical conformation for the most stable isomer (RRS-twist), while a slightly higher energy was found for an RRS-crown isomer with a syn orientation of the phosporyl groups. Surprisingly, all NMR studies (1H, 13C and 31P) of 7 are in agreement with a dynamic C2 symmetry in solution. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Wein…
Resorcarenes in the Boat Conformation as Building Blocks for Hydrogen-Bonded Assemblies Including Two Ammonium Cations
2001
Crystal structures are reported for various co-crystals of rccc-resorcarenes with triethylammonium chloride. Usually, two molecules of a C2v-symmetric tetraester 2 in the boat conformation are linked through four hydrogen-bonded chloride anions to give dimeric assemblies. Two of the chloride anions may be replaced by four hydrogen-bonded ethanol molecules in an otherwise similar structure. These assemblies, which consist of six or eight components, posses voluminous, negatively charged chambers in which two triethylammionium cations, 3+, are included as guests by strong electrostatic and hydrogen-bonding interactions. The host-guest N-H...Cl hydrogen bonds were clearly detected at 173 K. Th…
Cyclodextrin‐Calixarene Nanosponges as Potential Platforms for pH‐Dependent Delivery of Tetracycline
2019
Four mixed cyclodextrin-calixarene nanosponges were tested as possible Drug Delivery Systems, using Tetracycline antibiotic as a suitable model drug. The selected nanosponges featured a different composition ratio between the two host co-monomer components, and the possible presence of ionisable amine or carboxyl groups deriving from chemical post-modification. The pH-dependent absorption and release abilities of the materials were verified; in particular release kinetics showed the occurrence of a simple first-order profile. The antibacterial activity of nanosponge-tetracycline composites suitably prepared under sterile conditions was assayed towards both Gram-positive and Gram-negative ty…
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.