First 24-Membered Macrocyclic 1,10-Phenanthroline-2,9-Diamides-An Efficient Switch from Acidic to Alkaline Extraction of f-Elements.

A reaction of acyl chlorides derived from 1,10-phenanthroline-2,9-dicarboxylic acids with piperazine allows the preparation of the corresponding 24-membered macrocycles in good yield. The structural and spectral properties of these new macrocyclic ligands were thoroughly investigated, revealing promising coordination properties towards f-elements (Am, Eu). It was shown that the prepared ligands can be used for selective extraction of Am(III) from alkaline-carbonate media in presence of Eu(III) with an SFAm/Eu up to 40. Their extraction efficiency is higher than calixarene-type extraction of the Am(III) and Eu(III) pair. Composition of macrocycle-metal complex with Eu(III) was investigated by luminescence and UV-vis spectroscopy. The possibility of such ligands to form complexes of L:Eu = 1:2 stoichiometry is revealed.

Pyrrolidine-Derived Phenanthroline Diamides: An Influence of Fluorine Atoms on the Coordination of Lu(III) and Some Other f-Elements and Their Solvent Extraction.

Three pyrrolidine-derived phenanthroline diamides were studied as ligands for lutetium trinitrate. The structural features of the complexes have been studied using various spectral methods and X-ray. The presence of halogen atoms in the structure of phenanthroline ligands has a significant impact on both the coordination number of lutetium and the number of solvate water molecules in the internal coordination sphere. The stability constants of complexes with La(NO3)3, Nd(NO3)3, Eu(NO3)3, and Lu(NO3)3 were measured to demonstrate higher efficiency of fluorinated ligands. NMR titration was performed for this ligand, and it was found that complexation with lutetium leads to an approximately 13 ppm shift of the corresponding signal in the 19F NMR spectrum. The possibility of formation of a polymeric oxo-complex of this ligand with lutetium nitrate was demonstrated. Experiments on the liquid-liquid extraction of Am(III) and Ln(III) nitrates were carried out to demonstrate advantageous features of chlorinated and fluorinated pyrrolidine diamides.

A Promising 1,3,5-Triazine-Based Anion Exchanger for Perrhenate Binding: Crystal Structures of Its Chloride, Nitrate and Perrhenate Salts.

The reaction of pyridine with cyanuric chloride was studied under microwave activation as well as in the presence of silver nitrate. The product of hydrolysis containing two pyridinium rings and chloride anion was isolated. The structures of these anion exchanger salts with chloride, nitrate and perrhenate anions are discussed.

Competing Routes in the Extraction of Lanthanide Nitrates by 1,10-Phenanthroline-2,9-diamides: An Impact of Structure of Complexes on the Extraction.

The fact of the fracture of the extraction curve of lanthanides by 1,10-phenanthroline-2,9-diamides is explained in terms of the structure of complexes, solvent extraction data and quantum chemical calculations. The solvent extraction proceeds in two competing directions: in the form of neutral complexes LLn(NO3)3 and in the form of tight ion pairs {[LLn(NO3)2 H2O]+ (NO3-).

Synthesis and crystal structure of a new Cu3Au-type ternary phase in the Au-In-Pd system: distribution of atoms over crystallographic positions.

A new Cu3Au-type ternary phase (τ phase) is found in the AuPd-rich part of the Au-In-Pd system. It has a broad homogeneity range based on extensive (Pd,Au) and (In,Au) replacement, with the composition varying between Au17.7In25.3Pd57.0 and Au50.8In16.2Pd33.0. The occupancies of the crystallographic positions were studied by single-crystal X-ray diffraction for three samples of different composition. The sites with m-3m symmetry are occupied by atoms with a smaller scattering power than the atoms located on 4/mmm sites. Two extreme structure models were refined. Within the first, the occupation type changes from (Au,In,Pd)3(Pd,In) to (Au,Pd)3(In,Pd,Au) with an increase in the Au gross content. For the second model, the occupation type (Au,In,Pd)3(Pd,Au) remains essentially unchanged for all Au concentrations. Although the diffraction data do not allow the choice of one of these models, the latter model, where Au substitutes In on 4/mmm sites, seems to be preferable, since it agrees with the fact that the homogeneity range of the τ phase is inclined to the Au corner and provides the same occupation type for all the studied samples of different compositions.

Carboxylate-phenolate tautomerism in 5-[(nitrophenyl)diazenyl]salicylate anions.

Aryldiazenyl derivatives of salicylic acid and their salts are used as dyes. In these structures, the carboxylate groups are engaged in short contacts with the cations and in hydrogen bonds with water molecules, if present. If both O atoms of the carboxylate group take part in such interactions, the negative charge is delocalized over the two atoms. In the absence of hydrogen bonds and contacts with cations, the negative charge is localized on one of the O atoms. In the crystal structures of tetramethylammonium 2-hydroxy-5-[(E)-(4-nitrophenyl)diazenyl]benzoate and tetramethylammonium 2-hydroxy-5-[(E)-(2-nitrophenyl)diazenyl]benzoate, both C4H12N(+)·C13H8N3O5(-), all the interactions between the cations and anions are weak, and their effect on the geometry of the anions is negligible. Under these conditions, the 2-nitro-substituted anion is an almost pure phenol-carboxylate tautomer, whereas in the 4-nitro-substituted anion, the phenolic H atom is shifted towards the carboxylate group, and thus the structure of this anion is intermediate between the phenol-carboxylate and phenolate-carboxylic acid tautomeric forms. The probable formation of such an intermediate form is supported by quantum chemical calculations. Being the characteristic feature of this form, a short distance between the phenolic and carboxylate O atoms is observed in the 4-nitro-substituted anion, as well as in the structures of some 3,5-dinitrosalicylates reported in the literature.

syn and anti conformations in 2-hydroxy-5-[(E)-(4-nitrophenyl)diazenyl]benzoic acid and two related salts.

The crystal structures of 2-hydroxy-5-[(E)-(4-nitrophenyl)diazenyl]benzoic acid, C13H9N3O5, (I), ammonium 2-hydroxy-5-[(E)-phenyldiazenyl]benzoate, NH4(+)·C13H9N2O3(-), (II), and sodium 2-hydroxy-5-[(E)-(4-nitrophenyl)diazenyl]benzoate trihydrate, Na(+)·C13H8N3O5(-)·3H2O, (III), have been determined using single-crystal X-ray diffraction. In (I) and (III), the phenyldiazenyl and carboxylic acid/carboxylate groups are in an anti orientation with respect to each other, which is in accord with the results of density functional theory (DFT) calculations, whereas in (II), the anion adopts a syn conformation. In (I), molecules form slanted stacks along the [100] direction. In (II), anions form bilayers parallel to (010), the inner part of the bilayers being formed by the benzene rings, with the -OH and -COO(-) substituents on the bilayer surface. The NH4(+) cations in (II) are located between the bilayers and are engaged in numerous N-H···O hydrogen bonds. In (III), anions form layers parallel to (001). Both Na(+) cations have a distorted octahedral environment, with four octahedra edge-shared by bridging water O atoms, forming [Na4(H2O)12](4+) units.

4-Chloro-2-[(E)-(4-nitro-phen-yl)diazenyl]phenol.

The title compound, C(12)H(8)ClN(3)O(3), in the crystalline state and in solution, exists in the azo form, as predicted by density functional theory (DFT) calculations. The mol-ecule is approximately planar [the dihedral angle between the rings is 1.83 (8)°], with the nitro group slightly twisted [13.4 (2)°] relative to the benzene ring. Translationally related mol-ecules form stacks along [010] with an inter-planar distance of 3.400 (2) Å. The hydroxy group forms an intramolecular hydrogen bond with the azo N atom.

4-[(E)-1-Naphthyl-diazen-yl]phenol.

The title compound (C. I. Solvent Yellow 8), C(16)H(12)N(2)O, crystallizes with two crystallographically independent mol-ecules in the asymmetric unit. The planarity of both mol-ecules is slightly distorted, the dihedral angles between the benzene ring and the naphthalene system being 9.04 (8) and 5.69 (3)°. In the crystal, O-H⋯N hydrogen bonds between the hydr-oxy groups and azo N atoms link the two symmetry-independent mol-ecules into a polymeric chain propagating in [001].

Structural characterization of prazosin hydrochloride and prazosin free base.

The three-dimensional solid-state structures of prazosin hydrochloride, C19H22N5O4+.Cl- (A), and prazosin free base, C19H21N5O4 (B), have been determined by synchrotron X-ray powder diffraction. A and B crystallize in triclinic P-1 and monoclinic Cc space groups, respectively, with one structural unit per asymmetric part. In A and B, the prazosin molecule adopts different conformations, which do not correspond to those obtained by DFT optimizations of protonated and free prazosin.

Protonation site and hydrogen bonding in anhydrous and hydrated crystalline forms of doxazosin mesylate from powder data.

The three-dimensional solid-state structures of two modifications of doxazosin mesylate (C23H26N5O5)+.(CH3SO3)-, 4-amino-2-[4-[(2,3-dihydro-1,4-benzodioxin-2-yl)carbonyl]piperazin-1-yl]-6,7-dimethoxyquinazoline methanesulfonate, a commonly used antihypertensive agent, have been determined by synchrotron X-ray powder diffraction. An anhydrous form (A) and a dihydrate form (dG) crystallize in monoclinic space groups. In both forms the doxazosin molecule is protonated at the N1 atom of the quinazoline bicycle. The N1 atom, and the amino H atoms and O atoms of the mesylate moieties are involved in three-dimensional hydrogen-bonding networks, while solvent water molecules and carboxamide O atoms are also incorporated in a hydrogen-bonding network in dG.

Molecular crystals: the crystal field effect on molecular electronic structure.

The effect of crystal packing on the electronic structure of organic molecules was modeled by incorporation of the external electrostatic potential into the semiempirical Hamiltonian of the molecule. An empirical correction procedure was devised in order to compensate for systematic errors in the charge distribution typical of semiempirical methods. The model was applied to 79 crystal structures belonging to various syngonies and space groups. The effect of the crystal field is subject to wide variations depending on the crystal packing motif. The difference between the effect of the crystal field on the molecular electronic structure and the solvent effect modeled with COSMO is highlighted. The effect of intermolecular hydrogen bonds on the molecular electronic structure and electronic spectra was modeled with this approach, and it does not predominate over the effect of long-range electrostatic interactions. INDO/S calculations employing the crystal electrostatic potential give an insight into the origin of crystallochromy, in particular, they properly predict color difference for several groups of polymorphs.