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The crystal structure determines the properties of compounds and materials, although one can find simple yet industrially relevant compounds such as potassium acetate (KOAc) and its hydrates for which the properties and even the composition still remain misunderstood, owing to the lack of structural data. In this study, the crystal structures of KOAc polymorphs and hydrates were determined for the first time. The water content in the crystal hydrates was reliably determined revealing two new phases 3KOAc·2H 2 O and KOAc· x H 2 O ( x = 0.38-0.44), instead of the "sesquihydrate" and "hemihydrate" that for a century were believed to be the main hydrated forms of KOAc at ambient temperature. The number and nature of phase transitions were clearly established, and the hydration-dehydration processes were studied in detail by variable-temperature X-ray diffraction and thermal analyses.

Two novel 1,10-phenanthroline-2,9-diamide ligands were constructed on the basis of 2-phenylpyrrolidine and obtained as pure diastereomers. These ligands demonstrated advanced properties in liquid-liquid extraction tests. They revealed high efficiency of americium(III) extraction alongside with the record values of selectivity in the separation of americium from light lanthanides from strongly acidic media. An abrupt increase of extraction efficiency when moving along the lanthanide series from lanthanum to lutetium was observed. The examination of the extraction behavior of pure diastereomeric forms revealed noticeable differences in their selectivity while maintaining the overall extraction trend. The explanation of the discovered patterns was elucidated by a comprehensive study of the ability of the ligands to bind lanthanide nitrates in solutions. All the data collected (UV-vis and NMR titration, X-ray analysis of resulting complexes, solvation numbers estimation) were supported by quantum chemical calculation. These data clearly indicated that in the case of light lanthanides the formation of 1 : 1 complexes is most preferable. At the same time, complexes with heavy lanthanides, such as ytterbium and lutetium, exist as ionic pairs which may consist of [L 2 M] z+ cations counterbalanced by metallate anions, which may result in the formation of the species of unusual composition like L 2 M 2 or even L 4 M 5 clusters., (© 2024 Wiley-VCH GmbH.)

In this work, the influence of protonation on the kinetics and thermodynamics of extraction of the Am/Eu pair using N-heterocyclic dicarboxylic acid diamide N , N '-diethyl- N , N '-bis(4-ethylphenyl)-[2,2'-bipyridine]-6,6'-dicarboxamide ( L ) was investigated. The extraction efficiency of the ligand did not decrease, even at a nitric acid concentration 4 times higher than that of the ligand in the organic phase. X-ray diffraction analysis established that protonation leads to the preorganization of the ligand due to the reversal of bipyridyl rings into the binding conformation when both nitrogen atoms are turned to one side. Also, the effect of protonation on the chemical shifts of the functional binding groups (bipyridyl and amide) in solution was demonstrated by NMR spectroscopy. However, the presaturation of the organic phase with nitric acid did not lead to significant changes in the surface activity of the ligand. For extraction kinetics, a mechanism was proposed in which protonation and preorganization of the ligand was the limiting stage.

Hybrid N,O-donor ligands based on 1,10-phenanthroline are a promising class of compounds for processing high-level waste. Here, we synthesized novel phenanthroline-based diphosphonates containing electron-withdrawing fluorine atoms in alkyl substituents. We studied their extraction properties for Am(III) and, for the first time, for the entire series of lanthanides(III). The extraction of nitric acid for these diphosphonates was also studied. It has been shown that replacing one hydrogen atom with a fluorine atom in the ethyl substituent of a diphosphonate leads to a decrease in the affinity of the ligands for metal cations. Replacing two hydrogen atoms leads to a decrease in the affinity of the ligands for both metal cations and protons. But such modifications led to a change in the nature of the extraction of Am(III) and Eu(III) from nitric acid solutions, and as a result, the diphosphonate with two substituted hydrogen atoms retains its extraction properties when extracted from 5 mol/L HNO 3 . The complexation in solution was studied by using ultraviolet-visible (UV-vis) titration for Nd(NO 3 ) 3 and Eu(NO 3 ) 3 . The study of complexation in solid form using SC-XRD revealed the formation of complexes of the composition LnL(NO 3 ) 3 P(O)Phen(O) 2 ,κ 4 -(RO) 2 P(O)Phen(O) 2 (OR))(NO 3 ) 2 ] 2 . Density functional theory (DFT) calculations were performed to gain more insight into coordination properties and describe experimental data. It was shown that introducing fluorine atoms decreases the charge modules for both N phen and O P═O and decreases the protonation energy.

A systematic study of extraction systems for the separation of f -elements using the tetradentate N,O-donor diamide of 1,10-phenanthroline-2,9-dicarboxylic acid ( L ) in various molecular and ionic solvents was performed. It was demonstrated that the nature of a diluent has a significant impact on solvent extraction of Am(III) and Ln(III) and the stoichiometry of formed complexes with f -elements. The mechanism of complexation and forms of complexes in different diluents were investigated by radiometric methods, UV-vis titration, and XRD.

In this work, we studied the extraction systems for the separation f -elements based on the tetradentate N,O-donor ligand di( N -ethyl-4-ethylanilide) 2,2'-dipyridyl-6,6'-dicarboxylic acid ( L ). The organic phase of these systems was perspective fluorine-containing organic solvents-metanitrobenzotrifluoride ( F-3 ), ionic liquid C 4 mimNTf 2 ( IL ), and their mixture. The increase of Am(III) selectivity in the presence of Ln(III) in cases of the diluent mixture was shown. The mechanism of the f -element complexation leading to the improved properties of the extraction systems was studied by UV-visible, Raman-spectroscopy, XRD-study, and density functional theory calculations.

A variant of microfluidic setup design for the study of extraction kinetics has been proposed. Mass transfer constants for Am(III) and Eu(III) and observed rate constants were obtained for N-,O-donor ligands featuring phenanthroline and bipyridyl cores. The possibility of determining rate constants for cations independently of each other makes it possible to observe the kinetic effect of separation. The extraction rate was found to be lower for the bipyridyl ligand, compared to phenanthroline. The values of the rotation barriers for the ligands were calculated using the DFT method. The values correlate with the obtained low extraction rate for the bipyridyl ligand. Also, crystallographic data showing anti-conformation for the bipyridyl ligand align with the kinetic data. Surface tension was also determined for the systems with the studied ligands. It is shown that at equal ligand concentrations, the value of surface tension agrees with the extraction rate. Furthermore, it is shown that for the bipyridyl ligand, prior contact of the organic phase with nitric acid significantly affects the surface tension.

The search for new effective extractants is an important task for the management of high-level liquid waste (HLW) generated during the reprocessing of spent nuclear fuel. Here, we synthesized a series of diglycolamides with cyclic substituents for the first time. We disclosed their coordination with f-element nitrates [La(NO 3 ) 3 and UO 2 (NO 3 ) 2 ] by SC-XRD study and complexation properties toward Am(III), Ln(III), and U(VI) during solvent extraction from nitric acid solutions. Using dynamic nuclear magnetic resonance (NMR) and density functional theory (DFT) calculations, the importance of tautomerism in the extraction properties of diglycolamides was shown.

In this study, pyridine and phenanthroline diphosphonate ligands were investigated for the first time from the context of solvent extraction and potentiometric sensing of Co(II), Ni(II), Cu(II), Zn(II), Cd(II), and Pb(II) cations. The extraction efficiency under the same conditions for phenanthroline-diphosphonates is considerably higher than that for pyridine ligands. At the same time, the pyridine-diphosphonates show pronounced selectivity towards lead in this metal series. The extraction systems with phenanthroline diphosphonates provided the most efficient extraction of Cd(II) and Pb(II) cations ( D > 90). The newly developed pyridine and phenanthroline diphosphonate ligands have proven to be highly effective components in plasticized polymeric membranes. These ligands can be utilized to construct potentiometric ion sensors that exhibit a notable response specifically towards Pb(II) cations. Among the previously reported tetradentate ligands, the phenanthroline diphosphonate ligand, when incorporated into plasticized polymeric membranes, demonstrated the highest sensitivity towards d-metals and Pb(II). The structure of the single crystal complex of Pb(II) and Cd(II) with pyridine-diphosphonates was studied by X-ray diffraction analysis (XRD). The geometry of Cu(II), Zn(II), Cd(II) and Pb(II) complexes and the energy effect of the complex formation, including pseudo-oligomerization reactions, were determined by DFT calculations. The high sensing and extraction efficiency of diphosphonates with respect to Pb(II) is consistent with the minimum values of complex formation energies. The variation in sensory and extraction properties observed among the studied diphosphonate ligands is influenced by the ability to form polynuclear complexes with Pb(II) cations, whereas such properties are absent in the case of Cd(II) cations.

Though 2-arylperimidines have never been used in iridium(III) chemistry, the present study on structural, electronic and optical properties of N -unsubstituted and N -methylated 2-(2-thienyl)perimidines, supported by DFT/TDDFT calculations, has shown that these ligands are promising candidates for construction of light-harvesting iridium(III) complexes. In contrast to N -H perimidine, the N -methylated ligand gave the expected cyclometalated μ-chloro-bridged iridium(III) dimer which was readily converted to a cationic heteroleptic complex with 4,4'-dicarboxy-2,2'-bipyridine. The resulting iridium(III) dye exhibited panchromatic absorption up to 1000 nm and was tested in a dye-sensitized solar cell.

The title compounds, 2-(4-methylphenyl)-1 H -perimidine hemihydrate ( 1 , C 18 H 14 N 2 ·0.5H 2 O) and 1-methyl-2-(4-methylphenyl)-1 H -perimidine ( 2 , C 19 H 16 N 2 ), were prepared and characterized by 1 H NMR and single-crystal X-ray diffraction. The organic mol-ecule of the hemihydrate lies on a twofold rotation axis while the water mol-ecule lies on the inter-section of three twofold rotation axes (point group symmetry 222). As a consequence, the hydrogen atoms that are part of the N-H group and the water mol-ecule as well as the CH 3 group of the p -tolyl ring are disordered over two positions. In compound 1 , the perimidine and the 2-aryl rings are slightly twisted while its N -methyl-ated derivative 2 has a more distorted conformation because of the steric repulsion between the N -methyl group and the 2-aryl ring. In the crystal structures, mol-ecules of perimidine 2 are held together only by C-H⋯π contacts while the parent perimidine 1 does not exhibit this type of inter-action. Its crystal packing is established by inter-molecular N-H⋯O hydrogen bonds with the solvent water mol-ecules and additionally stabilized by π-π stacking., (© Kalle et al. 2022.)

Conventional cyclometalation of calix[4]arene bis(aryltriazoles) with iridium(III) chloride hydrate leads to unique meso architectures in which the Ir 2 Cl 2 core is cross-bound by two (C^N) 2 ligands, which allows further replacement of the chloride bridges with ancillary ligands while maintaining the dinuclear structures of the complexes having independent or coupled iridium pairs.

A series of bis-cyclometalated iridium(iii) complexes with 2-arylphenanthroimidazole "antenna" ligands containing electron-donor or withdrawing substituents and a more flexible ancillary aromatic β-diketone bearing the "anchoring" carboxymethyl function has been prepared. Thorough X-ray study of the complexes revealed significant structural strains caused by bulky cyclometalated 2-arylphenanthroimidazoles resulting in dramatic distortions of the iridium octahedron and even in twist of the phenanthrene fragment. The crystal data were corroborated by gas-phase DFT calculations whereby the geometry of the complexes was distorted in the same way. While redox potentials, absorption and emission maxima of the complexes displayed expected change upon the variation of the electron-donating ability of the cyclometalated ligands, the complexes readily exchanged the bidentate ancillary ligand in the presence of a negligible amount of protons that was inspected in solution by UV-Vis spectroscopy. Moreover, after hydrolysis of the carboxymethyl group the resulting complexes readily react with the surface of titanium dioxide giving unique binuclear structures in which the deprotonated carboxy group of the coordinated β-diketonate binds the second bis-cyclometalated unit by forming a four-membered metallacycle. Though the enhanced reactivity of the complexes is contrary to the common idea of the high inertness of iridium(iii) compounds it can be seen as a consequence of the interplay between the steric hindrance induced by the ligands and the strong preference of the iridium(iii) ion for octahedral geometry. This study demonstrates that the use of bulky ligands provides access to light-harvesting iridium(iii) complexes with required extent of lability which may be promising as photocatalysts and biologically active molecules.

The title compounds, 2-(pyridin-2-yl)-1 H -perimidine (C 16 H 11 N 3 ; 1 ), 1-methyl-2-(pyridin-2-yl)-1 H -perimidine (C 17 H 13 N 3 ; 2 ), and 1,3-dimethyl-2-(pyridin-2-yl)-1 H -perimidinium iodide (C 18 H 16 N 3 + ·I - ; 3 ) were synthesized under mild conditions and their structures were determined by 1 H NMR spectroscopy and single-crystal X-ray analysis. The N -methyl-ation of the nitro-gen atom( s ) at the perimidine moiety results in a significant increase of the inter-plane angle between the pyridin-2-yl ring and the perimidine system. The unsubstituted perimidine ( 1 ) forms a weak intra-molecular N-H⋯N bond that consolidates the mol-ecular conformation. In the crystal structures of 1 - 3 , the mol-ecular entities all are assembled through π-π and C-H⋯π inter-actions., (© Kalle et al. 2021.)

Cyclometalated Ru(ii) complexes with 2-arylbenzimidazole antenna ligands bearing electron-donor/withdrawing substituents and anchoring 4,4'-dimethoxycarbonyl-2,2'-bipyridine have been prepared and their structure, optical and electrochemical properties have been studied. The complexes possess enhanced light-harvesting characteristics compared to those of the standard N719 dye and absorb light up to 750 nm. In addition, they demonstrate reversible redox behavior with Ru3+/Ru2+ potentials being finely tuned by the change of the electron-donating ability of cyclometalated ligands. After a mild hydrolysis of dimethoxycarbonyl groups the excellent optical properties of the complexes remain unchanged and they show good efficiency when tested in dye-sensitized solar cells.

Currently, there is no imaging procedure for radionuclide therapy utilizing Erbium-169 (Er-169). We have recently published the first post-radiosynovectomy imaging of Er-169 citrate in a case report (Farahati et al., 2017). In this study, we performed in-vitro and in-vivo studies to evaluate the feasibility to assess the distribution of Er-169 citrate after radiosynovectomy in fourteen patients with seventeen affected joints treated for refractory chronic synovitis. Post-radiosynovectomy imaging revealed the feasibility of post-radiosynovectomy detection and distribution utilizing Er-169 citrate in all cases. However, additional in-vitro studies including in-vitro imaging, gamma spectrometry and analysis of half-life indicated that emitted gamma-rays of the Ytterbium-169 in the radiopharmaceutical together with bremsstrahlung induced by Er-169 are the imaging source of emitted counts. Post-radiosynovectomy imaging utilizing Er-169 citrate is feasible and should be implemented in the guidelines for theranostics for quality control, patient safety and therapy monitoring., (Copyright © 2019. Published by Elsevier Ltd.)

Iridium(III) is often considered to be one of the most inert octahedral metal ions. Herein we present a phenanthroimidazole-based bis-cyclometalated iridium(III) chloride undergoing a facile chloro ligand exchange with iodine, in a gas-solid reaction under ambient conditions. Monitoring the progress of the reaction by X-ray diffraction analysis reveals the crystal-packing-induced exceptional stereoselectivity of this topochemical transformation. The results provide excellent opportunities to modulate the geometry and kinetic properties of cyclometalated iridium(III) complexes that may be very promising in catalysis and design of anticancer agents., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Chimera states are complex spatio-temporal patterns that consist of coexisting domains of coherent and incoherent dynamics. We study chimera states in a network of non-locally coupled Stuart-Landau oscillators. We investigate the impact of initial conditions in combination with non-local coupling. Based on an analytical argument, we show how the coupling phase and the coupling strength are linked to the occurrence of chimera states, flipped profiles of the mean phase velocity, and the transition from a phase- to an amplitude-mediated chimera state.