Search results for "bonds"
showing 10 items of 155 documents
Anion Recognition by a Bioactive Diureidodecalin Anionophore: Solid-State, Solution, and Computational Studies
2018
Recent work has identified a bis-(p-nitrophenyl)ureidodecalin anion carrier as a promising candidate for biomedical applications, showing good activity for chloride transport in cells yet almost no cytotoxicity. To underpin further development of this and related compounds, a detailed structural and binding investigation is reported. Crystal structures of the transporter as five solvates confirm the diaxial positioning of urea groups while revealing a degree of conformational flexibility. Structures of complexes with Cl−, Br−, NO3 −, SO4 2− and AcO−, supported by computational studies, show how the binding site can adapt to accommodate these anions. 1H NMR binding studies revealed exception…
Structure of chloroantimonates(III) with an imidazolium cation: (C3H5N2)[SbCl4] and (C3H5N2)2[SbCl5]
2003
Abstract Two different chloroantimonates(III) with an imidazolium cation have been synthesized by the reaction of antimony trichloride and imidazole in an aqueous solution of hydrochloric acid. The crystals of (C3H5N2)[SbCl4] are monoclinic, space group C2/c, while (C3H5N2)2[SbCl5] crystallizes in the orthorhombic system, space group Pbcn. Both crystals are built of one dimensional zig-zag chains composed of [SbCl6]3− octahedra connected by edges and corners, respectively. The cavities between inorganic chains are filled by imidazolium cations. In both structures, one crystallographically independent imidazolium cation is rotationally disordered, and the positions of all atoms are split bet…
N-Alkyl Ammonium Resorcinarene Chloride Receptors for Guest Binding in Aqueous Environment
2016
Host systems with guest binding ability in water and/or biological fluids are a current challenge in supramolecular host–guest chemistry. Here we present the first syntheses of water-soluble N-ethanol ammonium resorcinarene chlorides (NARCls) with terminal hydroxyl groups at the upper rim. The NARCls possess deep cavities and are shown to bind a variety of guest molecules such as linear and cyclic alkanes, linear halogenated alkanes, and aromatic fluorophores (naphthalene, p-(phenylazo)phenol) in water through hydrophobic interactions, as well as 1,4-dioxane (a water soluble guest) via hydrogen bonds. The receptors are monomeric in aqueous media and form 1:1 host–guest complexes with bindin…
Orthorhombic polymorphs of twotrans-4-aminoazoxybenzenes
2002
The two isomeric compounds 4-amino-ONN-azoxybenzene [or 1-(4-aminophenyl)-2-phenyldiazene 2-oxide], i.e. the alpha isomer, and 4-amino-NNO-azoxybenzene [or 2-(4-aminophenyl)-1-phenyldiazene 2-oxide], i.e. the beta isomer, both C(12)H(11)N(3)O, crystallized from a polar solvent in orthorhombic space groups, and their crystal and molecular structures have been determined using X-ray diffraction. There are no significant differences in the bond lengths and valence angles in the two isomers, in comparison with their monoclinic polymorphs. However, the conformations of the molecules are different due to rotation along the Ar-N bonds. In the alpha isomer, the benzene rings are twisted by 31.5 (2)…
Halogen Bonded Analogues of Deep Cavity Cavitands
2014
The first examples of halogen bonded analogues of deep cavity cavitands with guest binding properties, formed between N-alkyl ammonium resorcinarene halides as acceptors and bromotrichloromethane as the donor, are reported in the solid state and in solution.
Analysis of the Legal and Regulatory Situation of Uncovered Corporate Bond Issuance in the Baltic States: is there a Common Framework Possible?
2021
While the development of the Baltic corporate bond market is based on the uncovered bond segment, the elaboration of the legislative base has a devoted emphasis on the covered bonds. The shift from a country-focused to the pan-Baltic-focused capital market has been publicly acknowledged by the governments (Ministry of Finance of the Republic of Latvia, 2018) and is in line with the ongoing Capital Markets Union initiative of the European Commission (The High Level Forum on the Capital Markets, 2020). Moreover, a pan-Baltic covered bond legal and regulatory framework has been initiated (Ministry of Finance of the Republic of Lithuania, 2019). The strong demand for the corporate bond segment …
Legal framework for secured corporate bonds in Latvia: proposal for a new regulation introducing the concept of a collateral agent
2019
Access to finance is considered as one of the key factors to successful financial market development. European companies face problems with corporate funding which is treated as one of the main barriers to corporate growth and innovation capacity. Corporate bonds represent an alternative source of funding, contributing to a reduction of dependency on more traditional bank financing. Despite the present growth of the corporate bond market in Latvia, the current legal environment for collateralization of the corporate bond in Latvia remains comparatively inflexible for the changes ongoing. The goal of this thesis is to provide a theoretical background for the procedure of issuance of secured …
Reversible, room-temperature C-C bond activation of benzene by an isolable metal complex
2019
The activation of C-C bonds is of fundamental interest in the construction of complex molecules from petrochemical feedstocks. In the case of the archetypal aromatic hydrocarbon benzene, C-C cleavage is thermodynamically disfavoured, and is brought about only by transient highly reactive species generated in situ. Here we show that the oxidative addition of the C-C bond in benzene by an isolated metal complex is not only possible, but occurs at room temperature and reversibly at a single aluminium centre in [(NON)Al]- (where NON = 4,5-bis(2,6-diisopropylanilido)-2,7-di-tert-butyl-9,9-dimethylxanthene). Selectivity over C-H bond activation is achieved kinetically and allows for the generatio…
Design of enzyme-mediated controlled release systems based on silica mesoporous supports capped with ester-glycol groups
2012
[EN] An ethylene glycol-capped hybrid material for the controlled release of molecules in the presence of esterase enzyme has been prepared. The final organic-inorganic hybrid solid S1 was synthesized by a two-step procedure. In the first step, the pores of an inorganic MCM-41 support (in the form of nanoparticles) were loaded with [Ru(bipy) 3]Cl 2 complex, and then, in the second step, the pore outlets were functionalized with ester glycol moieties that acted as molecular caps. In the absence of an enzyme, release of the complex from aqueous suspensions of S1 at pH 8.0 is inhibited due to the steric hindrance imposed by the bulky ester glycol moieties. Upon addition of esterase enzyme, del…
The chemical bonds in CuH, Cu2, NiH, and Ni2 studied with multiconfigurational second order perturbation theory
1994
The performance of multiconfigurational second order perturbation theory has been analyzed for the description of the bonding in CuH, Cu2, NiH, and Ni2. Large basis sets based on atomic natural orbitals (ANOS) were employed. The effects of enlarging the active space and including the core‐valence correlation contributions have also been analyzed. Spectroscopic constants have been computed for the corresponding ground state. The Ni2 molecule has been found to have a 0+g ground state with a computed dissociation energy of 2.10 eV, exp. 2.09 eV, and a bond distance of 2.23 Å. The dipole moments of NiH and CuH are computed to be 2.34 (exp. 2.4±0.1) and 2.66 D, respectively. pou@uv.es ; merchan@…