Preparation and structure of [iiii] tetraphosphonatocavitands bearing long chain functionality at the lower rim: Metal picrates extraction studies

The stereoselective synthesis of the iiii stereoisomer of novel tetraphosphonato-cavitands derived from resorc [4]arene is reported. o-Nitrophenyl-n-octyl ether and n-undecyl-n-decanyl thioether functionalities were introduced in the lower rim of 1 and 2, respectively, to develop new molecular devices. The crystal structure of the solvated cavitand 1.6CH(3)CN was elucidated by X-ray crystallography. C104H104O24N4P4.6CH(3)CN crystallizes in the monoclinic space group P2(1)/c, a = 20.574(4), b = 16.591(4), c = 33.973(7) Angstrom, beta = 92.09(2)degrees, V = 11589(4) Angstrom(3), Z = 4, R = 0.065. The host molecule has the iiii configuration with the four P=O bonds oriented towards the molecular cavity. The affinity of molecules 1 and 2 for metal cations was investigated by the liquid-liquid extraction method: among the investigated metal picrates, Ag+, Ba2+ and Eu3+ were the best-extracted cations

Synthesis, molecular structure, and binding properties of a hemispherand incorporating a phosphoryl hard donor group

Phosphahemispherand 3 was synthesized in 63 % yield from its macrocyclic precursor 2 and 1,3-propanediol ditosylate in the presence of NaH in THF. Host 3 exhibited temperature-dependent H-1, Cl-13 and P-31 NMR spectra owing to conformational exchange throughout the molecular framework. Exo and endo conformers are in equilibrium in solution, and the energy barrier between the two forms is 61 kJ mol(-1). Two exo conformers, with the P=O bond directed away from the macrocyclic cavity, were predominant at low temperature. The major form was assigned to the C-s symmetry exo conformation, The minor exo form was assigned to the asymmetric conformation that has one methoxy group on each face of the macroring. The energy barrier for interconversion between the two exo forms is 56 kJ mol(-1). The binding energies of alkali metal and ammonium cations to 2 and 3 wore measured by the picrate extraction technique, The highest K-a values were obtained for the complexes of 3 with K+ and Rb+. The conformational changes observed upon complexation were examined by NMR spectroscopy and X-ray analysis and are discussed in terms of pre organization, The formation of 1:1 complexes was only observed with the endo conformer

A new supramolecular assembly obtained from the combination of silver(I) cations with a thiophosphorylated cavitand

The new tetra-thiophosphonatocavitand 1 in its iiii configuration extracts quantitatively Ag+ ions from aqueous solutions; the tetranuclear complex [1(2).Ag(4)Pic(4)] was selectively formed and characterized in the solid state by X-ray diffraction which revealed the formation of a new dimeric assembly through Ag+ coordination

Formation and X-ray structural characterization of the chiral and racemic forms of a bis-macrocyclic phosphoramide

The 1,3,2,4-diazadiphosphetidine ring 1, bearing two macrocyclic units, reacts with ethanol to form the chiral bis-macrocycle 2, including an asymmetric phosphorus center. 2 has been isolated as its chiral and racemic crystalline forms; both were structurally characterized using X-ray crystallography. The bis-macrocyclic molecule has a similar shape in the two crystal forms. A water molecule is complexed in one of the macrocylic units, inducing strong conformational changes respectively to the uncomplexed one

A Macrobicyclic Thiophosphonamide Polyether Ligand

Two crystal structures of a macrobicyclic oligoether compound, 31-phenyl-8,11,14,17,20-pentoxa-1,27-diaza-31-phosphatetracyclo[25.3.1.0(2,7).0(21,26)]henitriaconta-2,4,6,21,23,25-hexaene 31-sulfide, C29H35N2O5PS, (1), containing a thiophosphonamide group, are described. The molecules in the two crystals, (I) and (II), exhibit very similar conformations except for a disordered part in crystal form (II). A macrocyclic cavity appears in both conformations, although some O atoms of the O(CH2CH2O)(4) bridge are turned outwards. The propyl bridge and the phenyl group of the diazaphosphorinane moiety lie close to the sides of the macrocycle. The thiophosphoryl group is directed outwards

On the quantitative measure of a sonochemical effect in heterogeneous sonochemistry

The measurement of a sonochemical effect (SE) requires the definition of the reference conditions for the so-called “silent reaction”. It is shown that it is impossible to define SE correctly in the case of heterogeneous reactions, due to the dramatic effect of the agitation on reaction rates. This is true not only from the quantitative point of view (effect of ultrasound on reaction rates) but also from the qualitative perspective (change of reaction pathway when ultrasound is applied). The first, and most dramatic, example of chemical switching described in the literature, and claimed to be due to ultrasound, is proven also to be observable under efficient agitation conditions.FLWINinfo:eu-repo/semantics/publishe