Search results for "Solid"
showing 10 items of 3575 documents
Recognition of Li+ by a Salophen−UO2 Homodimeric Complex
2009
Self-assembly via mutual U-coordination of the salophen-UO(2) complex 1 creates a dimeric species which is shown to be useful for metal binding. Indeed, the 1 dimer has affinity for alkali metal cations and, interestingly, a marked selectivity for Li(+), determined by electrospray ionization mass spectrometry and (1)H NMR techniques. X-ray diffraction helped in the elucidation of the dimeric complex structure, which presents a crown-ether-type coordination site, in analogy to the more familiar 12-crown-4, responsible for the metal interaction. Comparison with isomer 2, and the salen derivative 3, increases the understanding of the behavior of such systems in solution and in the solid state.
Synthesis and crystal structure of {Rh2(O2CCH3)4·P(o-CH3OH6H4)Ph2}2. A novel dirhodium(II) monoadduct with intermolecular μ-oxo interactions
1997
Abstract We have investigated the reaction of dirhodium tetraacetate with the phosphine P( o -CH 3 OH 6 H 4 )Ph 2 (P) under different experimental conditions. From these reactions we have been able to isolate the dirhodium tetraacetate phosphine mono-adduct. The crystal structure shows that in the solid state this compound forms a centrosymmetric dimer of the dimer, {Rh 2 (O 2 CCH 3 ) 4 ·P(0-CH 3 OC 6 H 4 )Ph 2 } 2 , in which we oxygen atom from one acetate group in one Rh 2 (O 2 CCH 3 ) 4 ·P unit is axially coordinating one Rh atom on another Rh 2 (O 2 CCH 3 ) 4 · P unit (Rh⋯) 2.347(3) A intermolecular versus Rh⋯O 2.455(3) A intermolecular), and vice versa. The RhRh bond distance is 2.414…
Folding Patterns in a Family of Oligoamide Foldamers
2015
A series of small, unsymmetrical pyridine-2,6-dicarboxylamide oligoamide foldamers with varying lengths and substituents at the end groups were synthetized to study their conformational properties and folding patterns. The @-type folding pattern resembled the oxyanion-hole motifs of enzymes, but several alternative folding patterns could also be characterized. Computational studies revealed several alternative conformers of nearly equal stability. These folding patterns differed from each other in their intramolecular hydrogen-bonding patterns and aryl-aryl interactions. In the solid state, the foldamers adopted either the globular @-type fold or the more extended S-type conformers, which w…
Synthesis of a technetium-99m labelledL-tyrosine derivative with thefac-99mTc(I)(CO)3-core using a simple kit-procedure
2004
Summary The synthesis of a novel technetium-99m labelled derivative of l-tyrosine as a potential tumour imaging agent for nuclear medicine diagnosis is reported. The synthesis involved the labelling precursor fac-[ 99m Tc(OH2)(CO)3] + which was synthesized using the commercially available Isolink 1 -labelling kit and the tyrosine derivative O-(N,Nbis(carboxymethyl)aminoethyl)-l-tyrosine trifluoroacetate. The labelled compound O( 99m Tc(I)-tricarbonyl-N,N-bis(carboxymethyl)aminoethyl)-l-tyrosine was obtained in a radiochemical yield of 70–80% within 60 min with a radiochemical purity greater than 98% without any HPLC purification step. Purification was achieved merely by solid phase extracti…
Investigations on organotin, organolead, lead(IV), and lead(II) dithiolates
1985
Abstract Bis(triorganometal) 1,2-dithiolates (R3M)2S2R′ [(HS)2R′ = C7H8S2 for toluene-dithiol-3,4 (H2TDT); M = Sn, Pb; R = Ph; or (HS)2R′ = C10H14S2 for 1,2-dimethyl-4,5-bis(mercaptomethyl)benzene (H2DBB); M = Sn, R = CH3, C6H5; M = Pb, R = C6H5], diorganometal 1,2-dithiolates R2MS2R′ [(HS)2R′ = C6H6S2 for 1,2-dimercaptobenzene (H2DMB); M = Pb, R = CH3, C2H5, C6H5; or (HS)2R′ = H2TDT; M = Sn, R = CH3, C6H5; M = Pb, R = C6H5; or (HS)2R′ = H2DBB; M = Sn, R = CH3, C6H5; M = Pb, R = CH3, C2H2, C6H5; or (HS)2R′ = C8H6N2S2 for 2,3-dimercaptoquinoxaline (H2QDT); M = Pb, R = C6H5] and some lead(IV) and lead(II) dithiolates Pb(S2R′)n [(HS)2R′ = H2DMB, n = 2; (HS)2R′ = H2TDT, n = 2; (HS)2R′ = H2DBB, …
Effects of side chains of oxatub[4]arene on its conformational interconversion, molecular recognition and macroscopic self-assembly.
2017
A series of oxatub[4]arenes with different alkyl side chains have been synthesized. The conformational interconversion, molecular recognition and macroscopic self-assembly behaviour of oxatub[4]arene derivatives were investigated. The difference in side chains slightly changes the binding affinities, but results in different self-assembly morphologies at the solid state.
Organoelement derivatives of steroids: Synthesis and structural features of organosilicon, -tin and -lead derivatives of cholesterol and desoxycholic…
1987
Some organo-Main-Group-IV-element compounds of steroids of the type R3M(COL), R2Sn(COL)2 and (R3M)2(HDCA) (where R = Me or Ph; M = Si, Sn and Pb; HCOL = cholest-5-en-3β-ol; H3DCA = 3α, 12α-dihydroxy-5β-cholan-24-oic acid), have been synthesized. The structures of these compounds have been investigated by vibrational, mass, NMR (1H, 13C, 29Si, 119Sn and 207Pb) and 119Sn Mossbauer spectroscopy. For Me3Sn(COL) both in solution and in the solid state an associated structure with distorted trigonal bipyramidal geometry around tin and three-coordinated oxygen atoms is postulated. Discrete tetrahedral geometries are assigned to Ph3M(COL) complexes and to R2Sn(COL)2 complexes in solution. The latte…
Inclusion complexes of Cethyl-2-methylresorcinarene and pyridine N-oxides: breaking the C–I⋯−O–N+ halogen bond by host–guest complexation
2016
C ethyl-2-Methylresorcinarene forms host–guest complexes with aromatic N-oxides through multiple intra- and intermolecular hydrogen bonds and C–H⋯π interactions. The host shows conformational flexibility to accommodate 3-methylpyridine N-oxide, while retaining a crown conformation for 2-methyl- and 4-methoxypyridine N-oxides highlighting the substituent effect of the guest. N-Methylmorpholine N-oxide, a 6-membered ring aliphatic N-oxide with a methyl at the N-oxide nitrogen, is bound by the equatorial −N–CH3 group located deep in the cavity. 2-Iodopyridine N-oxide is the only guest that manifests intermolecular N–O⋯I–C halogen bond interactions, which are broken down by the host resulting i…
Breaking Bonds and Forming Nanographene Diradicals with Pressure.
2017
New anthanthrone-based polycyclic scaffolds possessing peripheral crowed quinodimethanes have been prepared. While the compounds adopt a closed-shell butterfly shaped structure in the ground state, a concave-to-convex fluxional dynamic inversion is accessible with a low energy barrier through an open-shell diradicaloid transition-state. Mainly driven by the release of strainattributed to the steric hindrance at the peri position of the anthanthrone core, a low-lying open-shell diradical is accessible through planarization of the core, which can be achieved by thermal excitation in solution. Alternatively, planarization can be achieved by application of mild pressure in the solid state, in w…
Exploration of the Solid-State Sorption Properties of Shape-Persistent Macrocyclic Nanocarbons as Bulk Materials and Small Aggregates.
2020
Porous molecular materials combine benefits such as convenient processability and the possibility for atom-precise structural fine-tuning which makes them remarkable candidates for specialty applications in the areas of gas separation, catalysis, and sensing. In order to realize the full potential of these materials and guide future molecular design, knowledge of the transition from molecular properties into materials behavior is essential. In this work, the class of compounds termed cycloparaphenylenes (CPPs)-shape-persistent macrocycles with built-in cavities and radially oriented π-systems-was selected as a conceptually simple class of intrinsically porous nanocarbons to serve as a platf…