Role of H in Solvent Extraction of Am(III) and Eu(III) Using a Polydentate Bipyridine N-,O-Donor Ligand: Chemical Equilibrium States and Kinetic Aspects.

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 ,'-diethyl-,'-bis(4-ethylphenyl)-[2,2'-bipyridine]-6,6'-dicarboxamide () 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.

Coordination of Fluorine-Substituted 1,10-Phenanthroline Diphosphonates with Americium(III) and Lanthanides(III): Solvent Extraction, Complexation, XRD, and Theoretical Study.

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).

Bipyridyldicarboxamides and f-metals: the influence of electron effects on the structure, stability, separation, and photophysical properties of their complexes.

In this work, three isomeric fluorinated bipyridyldicarboxamides were studied to evaluate the impact of the fluorine atom position on the structure, stability, Am(III)/Ln(III) separation, and photophysical properties of their complexes. The complexes of the fluorinated amides have a metal-to-ligand composition of 1 : 1, which is independent of the fluorine atom position or lanthanide metal. The bipyridyl fragments in the fluorinated complexes are flattened compared with those in unsubstituted ones.

Pyridine Diphosphonate Ligand for Stabilization of Tetravalent Uranium and Neptunium in Aqueous Medium under Aerobic Conditions.

Though uranium is usually present in its +6 oxidation state (as uranyl ion) in aqueous solutions, its conversion to oxidation states such as +4 or +5 is a challenging task. Electrochemical reduction and axial oxo activation are the preferred methods to get stable unusual oxidation states of uranium in an aqueous medium. In previous studies, dicarboxylic acid has been used to stabilize UO in aqueous alkaline solutions.

Kinetic features of solvent extraction by N,O-donor ligands of f-elements: a comparative study of diamides based on 1,10-phenanthroline and 2,2'-bipyridine.

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.

Small Cyclic Diglycolamides: Tautomerism, Solvent Extraction and Coordination with -Elements: One Strain to Rule Them All.

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) and UO(NO)] by SC-XRD study and complexation properties toward Am(III), Ln(III), and U(VI) during solvent extraction from nitric acid solutions.

Sensing and extraction of hazardous metals by di-phosphonates of heterocycles: a combined experimental and theoretical study.

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.

Intramolecular Re···O Nonvalent Interactions as a Stabilizer of the Polyoxorhenate(VII).

The first polyoxorhenate(VII) compound, pyrazolium polyoxorhenate ((CNH)ReO), and two new rhenium(VII) and technetium(VII) salts have been synthesized and studied. The structure of TcO has been reinvestigated. The [ReO] polyoxoanion contains four Re(VII) atoms: one with an octahedral environment and three with a tetrahedral environment.

Solvent Extraction and Conformation Rigidity: Actinide(IV) and Actinide(VI) Come Together.

The first comprehensive structural and extraction study of a 2,2'-bipyridine-6,6'-dicarboxamide ( diamide) extractant for U, Np, Pu, Th, Am, and Eu ions showed great potential for actinide separation due to steric hindrance of the amidic side phenyl ring of the given compound. The study of the complexes of An(VI) and Th(IV) with 2,2'-bipyridyldicarboxamide-type extractants demonstrated the structure of the extraction species for the first time. Investigation of the extraction properties with the radiometric and millimolar quantities of actinides showed similar extraction trends.

Pyridine-di-phosphonates as chelators for trivalent f-elements: kinetics, thermodynamic and interfacial study of Am(III)/Eu(III) solvent extraction.

The fractionation of high-level radioactive waste from nuclear power plants simplifies the handling of its components, and facilitates the reduction of radiotoxic effects on the environment. The search and study of new ligands for solvent extraction, as one of the methods in fractionation, remains a complex and important research task. In this work, four pyridine diphosphonate ligands were synthesized.

Novel cis-Pt(II) Complexes with Alkylpyrazole Ligands: Synthesis, Characterization, and Unusual Mode of Anticancer Action.

One concept of improving anticancer effects of conventional platinum-based antitumor drugs consists of conjugating these compounds with other biologically (antitumor) active agents, acting by a different mechanism. Here, we present synthesis, physicochemical characterization, biological effects, and mechanisms of action of four new analogs of conventional cisplatin, namely, cis-Pt(II) complexes containing either methyl or ethyl pyrazole N-donor ligands and chlorido or iodido ligands. It is noteworthy that while chlorido complexes display activity in a variety of cancer cell lines comparable to cisplatin, iodido complexes are considerably more potent due to their enhanced hydrophobicity and consequently enhanced cellular accumulation.

Way to Enforce Selectivity via Steric Hindrance: Improvement of Am(III)/Eu(III) Solvent Extraction by Loaded Diphosphonic Acid Esters.

Hybrid donor extractants are a promising class of compounds for the separation of trivalent actinides and lanthanides. Here, we investigated a series of sterically loaded diphosphonate ligands based on bipyridine (BiPy-PO-iPr and BiPy-PO-cHex) and phenanthroline (Phen-PO-iPr and Phen-PO-cHex). We studied their complex formation with nitrates of trivalent f-elements in solvent extraction systems (Am and Eu) and homogeneous acetonitrile solutions (Nd, Eu, and Lu).

Influence of a N-Heterocyclic Core on the Binding Capability of N,O-Hybrid Diamide Ligands toward Trivalent Lanthanides and Actinides.

N,O-hybrid diamide ligands with N-heterocyclic skeletons are one of the promising extractants for the selective separation of actinides over lanthanides in a highly acidic HNO solution. In this work, three hard-soft donor mixed diamide ligands, pyridine-2,6-diylbis(pyrrolidin-1-ylmethanone) (Pyr-PyDA), 2,2'-bipyridine-6,6'-diylbis(pyr-rolidine-1-ylmethanone) (Pyr-BPyDA), and (1,10-phenanthroline-2,9-diyl)bis(pyrrolidin-1-ylmethanone) (Pyr-DAPhen), were synthesized and used to probe the influence of N-heterocyclic cores on the complexation and extraction behaviors with trivalent lanthanides and actinides. H NMR titration experiments demonstrated that 1:1 metal-to-ligand complexes were mainly formed between the three ligands and lanthanides, but 1:2 type complexes were also formed between tridentate Pyr-PyDA and Lu(III).

Comparative Investigation into the Complexation and Extraction Properties of Tridentate and Tetradentate Phosphine Oxide-Functionalized 1,10-Phenanthroline Ligands toward Lanthanides and Actinides.

Two new phosphine oxide-functionalized 1,10-phenanthroline ligands, tetradentate 2,9-bis(butylphenylphosphine oxide)-1,10-phenanthroline (BuPh-BPPhen, L ) and tridentate 2-(butylphenylphosphine oxide)-1,10-phenanthroline (BuPh-MPPhen, L ), were synthesized and studied comparatively for their coordination with trivalent actinides and lanthanides. The complexation mechanisms of these two ligands toward trivalent f-block elements were thoroughly elucidated by NMR spectroscopy, UV/vis spectrophotometry, fluorescence spectrometry, single-crystal X-ray diffraction, solvent extraction, and theoretical calculation methods. NMR titration results demonstrated that 1 : 1 and 1 : 2 (metal to ligand) lanthanides complexes formed for L , whereas 1 : 1, 1 : 2 and 1 : 3 lanthanide complexes formed for L in methanol.

Diamidophosphites from β-hydroxyamides: readily assembled ligands for Pd-catalyzed asymmetric allylic substitution.

Two groups of modular chiral diamidophosphite ligands were easily synthesised from accessible N-Boc-amino alcohols and pseudodipeptides. The reaction of these compounds with [Pd(allyl)Cl] in the presence of AgBF yielded complexes [Pd(allyl)(L)]BF. In addition, metallochelates [Pd(allyl)(L)]BF with (S)-methioninol-based P,S-bidentate ligands were prepared.

Effect of Heterocyclic Ring on Ln Coordination, Luminescence and Extraction of Diamides of 2,2'-Bipyridyl-6,6'-Dicarboxylic Acid.

We have synthesized and examined several complexes of lanthanides with diamides of 2,2'-bipyridyl-6,6'-dicarboxylic acid bearing various hetaryl-based side chains for the elucidation of the effect of the heterocycle on the structure and properties of the ligands. The multigram scale methods for the preparation of various -alkyl-hetaryls and their diamides were developed. The solid state structure of 6-methyl-2-pyridylamide of 2,2'-bipyridyl-6,6'-dicarboxylic acid possesses a flat structure where the conformation is completely different from that previously observed for -alkylated 2,2'-bipyridyl-6,6'-dicarboxamides and 2,6-pyridinedicarboxamides.

The Fischer-Tropsch reaction in the aqueous phase over rhodium catalysts: a promising route to selective synthesis and separation of oxygenates and hydrocarbons.

In the present communication, we uncovered the aqueous phase Fischer-Tropsch reaction over rhodium catalysts. The reaction results in the synthesis and consecutive separation of hydrocarbons and oxygenates into two phases. Use of a rhodium Schiff base complex as a precursor for catalyst preparation allows efficient control of the Rh metal nanoparticle size distribution and leads to higher alcohol selectivity.

Unfolding the complexation and extraction of Am and Eu using N-heterocyclic aromatic diphosphonic acids: a combined experimental and DFT study.

Phosphonate based ligands are well known for the extraction of 'f' block elements. Three N,O-donor N-heterocyclic aromatic diphosphonate ligands were evaluated in the present work for the extraction/separation studies of Am and Eu. Complexation studies in aqueous medium using luminescence titration indicated the formation of anionic complexes in the case of Eu.

Sandwich double-decker Er(iii) and Yb(iii) complexes containing naphthalocyanine moiety: synthesis and investigation of the effect of a paramagnetic metal center.

Novel heteroleptic Er(iii) and Yb(iii) naphthalocyaninato-phthalocyaninates containing an octa-phenyl or octa-phenoxysubstituted naphthalocyanine deck were synthesised and identified by H NMR, EPR and high resolution MALDI-TOF/TOF mass spectrometry. Direct synthesis of novel homoleptic Yb(iii) bis (octa-phenylnaphthalocyaninate) was carried out. Downfield lanthanide induced shifts of the aromatic protons in target compounds were observed compared with the corresponding diamagnetic Lu(iii) complexes.

The lanthanide complexes of 2,2'-bipyridyl-6,6'-dicarboxylic dimethylanilides: the influence of a secondary coordination sphere on the stability, structure, luminescence and f-element extraction.

Four of the six possible isomeric 2,2'-bipyridyl-6,6'-dicarboxylic dimethylanilides were studied from the point of view of the impact of a secondary coordination sphere on the formation of complexes with lanthanides in solution, as well as the crystal structure and photophysical properties of the complexes. All ligands form complexes with a 1 : 1 metal-to-ligand ratio with an lg β1 in the range of 6.0-8.

Hard-and-soft phosphinoxide receptors for f-element binding: structure and photophysical properties of europium(iii) complexes.

New phosphinoyl-containing tetradentate heterocycles preorganised for metal ion binding were designed and prepared in high yields. The X-ray structures of two allied phosphinoyl-bearing 2,2'-bipyridyl and phenanthroline ligands, as well as closely related structures of 2,6-bis(diphenylphosphinoyl)pyridine and 9-(diphenylphosphinoyl)-1,10-phenanthroline-2-one, are reported. Complexes of nitrates of several lanthanides and trifluoroacetate of Eu(iii) with two phosphinoyl-bearing 2,2'-bipyridyl and phenanthroline ligands were isolated and characterised.

meso-Phenyltetrabenzotriazaporphyrin based double-decker lanthanide(III) complexes: synthesis, structure, spectral properties and electrochemistry.

A series of half-sandwich and sandwich-type lanthanide(III) complexes have been prepared using tetrabenzotriazaporphyrin ligands. Reaction of 27-phenyl-29H,31H-tetrabenzo[b,g,l,q][5,10,15]-triazaporphyrin (PhTBTAPH2, 1) with salts [LnX3]·nH2O (Ln = Eu (a), Lu (b); X = OAc, acac) afforded the single- and homoleptic double-deckers (PhTBTAP)LnOAc (2) and (PhTBTAP)2Ln (3) respectively. Heteroleptic double-decker compounds (PhTBTAP)LnPc (4a,b) were obtained upon interaction of 1 with the corresponding Ln mono(phthalocyaninates).

Heteroleptic naphthalo-phthalocyaninates of lutetium: synthesis and spectral and conductivity properties.

Novel heteroleptic naphthalo-phthalocyaninates of lutetium possessing a symmetrical substituted naphthalocyanine deck were synthesized on the basis of two preformed synthetic blocks: naphthalocyanine ligand and lutetium phthalocyaninates. The compounds obtained were characterized by (1)H NMR and high-resolution MALDI-TOF/TOF mass spectrometry. The correlation between the nature of the substituents and the spectral properties of the target complexes was determined by the introduction of electron-donating (aryl-, aryloxy-) or electron-withdrawing (chloro-) substituents into the phthalocyanine deck.

Novel near-IR absorbing phenyl-substituted phthalo- and naphthalocyanine complexes of lanthanide(III): synthesis and spectral and electrochemical properties.

A series of novel phenyl-substituted planar and sandwich-type complexes of Eu, Er and Lu with phthalo and naphthalocyanine ligands was obtained. A successful synthesis of dinaphthalocyanines from the ligand is described. A selective synthetic approach to the phenyl-substituted triphthalocyanine complexes from the ligand and acetylacetonate salts of lanthanides was developed.

Bis(tetrabenzotriazaporphyrinato) and (tetrabenzotriazaporphyrinato)(phthalocyaninato) lutetium(III) complexes--novel sandwich-type tetrapyrrolic ligand based NIR absorbing electrochromes.

The first sandwich-type complexes have been prepared for tetrabenzotriazaporphyrin ligands. The compounds reveal intrinsic UV-Vis/NIR absorption as well as peculiar electrochromic behavior. The heteroleptic (tetrabenzotriazaporphyrinato)(phthalocyaninato) lutetium derivative shows intermediate spectral and electrochemical properties with respect to homoleptic relatives.