Studies on a new solid–liquid Cs separation using the ionic liquid extraction system in comparison with the conventional adsorption

The process characteristics of a new solid–liquid Cs⁺ separation from the radioactive liquid waste using a crown ether dicyclohexano-18-crown-6 as an extractant and an ionic liquid of 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide were studied. The physicochemical properties of the precipitate containing Cs⁺ which is an solid–liquid extraction product were investigated to identify the solid–liquid phase separability and Cs⁺ loading. The Cs⁺ separation process performances were compared experimentally with those of the conventional adsorption system for pretreatment requirement and the amount of Cs⁺ waste. It was observed that the solid–liquid separation method using ILs has high Cs⁺ separation performance especially in the low Cs⁺ concentration.

     

Influence of the nature of the substituent in 3-(2-pyridyl)-1,2,4-triazole for complexation with Pd<Superscript>2+</Superscript>

The structure of four new palladium complexes [Pd(HL ² )Cl ₂ and Pd(L ^1–3 ) ₂ ] with 3-(2-pyridyl)-5-R-1,2,4-triazoles (R=H, CH₃, Ph respectively HL ¹ , HL ² , HL ³ ) was proposed based on IR, NMR, UV spectroscopy and MALDI mass spectrometry data analysis. It is found that the complexation of HL ² and HL ³ with Pd²⁺ ions results in a decrease of their fluorescence intensity and it is vice versa in case of HL ¹ . Furthermore, the influence of the substituent (R) in the 3-(2-pirydyl)-5-R-1,2,4-triazoles on the fluorescent and protolytic properties of HL ^1–3 was investigated.     

Synthesis,scope, <Superscript>1</Superscript>H and <Superscript>13</Superscript>C spectral assignments of isomeric dibenzofuran carboxaldehydes

Two isomeric dibenzofuran carboxaldehydes, namely 2-methoxydibenzo[b,d]furan-1-carbaldehyde (4) and 2-methoxydibenzo[b,d]furan-3-carbaldehyde (5), were synthesized. Formylation of 2-methoxydibenzo[b,d]furan (3) with α,α-dichloromethyl methyl ether and tin(IV) chloride gave a mixture of aldehydes 4 and 5 in 95 % yield and in a 35:65 ratio. Their ¹H and ¹³C NMR spectral signals were not sufficiently resolved in CDCl₃ solution to achieve their complete assignment, but this was possible in DMSO-d ₆ with the help of 2D-NMR techniques: NOESY for ¹H–¹H interactions and HSQC and HMQC experiments for ¹H–¹³C correlations. These aldehydes were used in the synthesis of novel β-phenylethylamines and NBOMe derivatives, which are undergoing biological evaluation.     

Synthesis,Structure, and Magnetic Properties of a Twist Linear Tetranuclear Co<Stack><Subscript>2</Subscript><Superscript>III</Superscript></Stack>Ln<Stack><Subscript>2</Subscript><Superscript>III</Superscript></Stack> Complexes

A series of twist linear tetranuclear 3d–4f Co ₂ ^III Ln ₂ ^III [Ln = Gd (1), Tb (2), Dy (3), Ho (4), Er (5)] complexes have been prepared under solvothermal conditions and structurally characterized with Schiff-base ligand 2-(((2-hydroxy-3-methoxyphenyl)methylene)amino)-2-(hydroxymethyl)-1,3-propanediol (H₄L). The two central Co ions are linked by two alkoxyl oxygen atoms, and one Ln ion lying above and the other below the Co–Co dimer, form a twist linear array. The magnetic susceptibility studies reveal antiferromagnetic or ferromagnetic behaviour, whilst dynamic magnetic studies indicate no slow magnetic relaxation for these complexes.     

Friedlander synthesis of highly functionalized isoxazolyl quinoline libraries via addition of C(sp3)–H bond to aldehydes

A novel protocol for ionic liquid (IL)-mediated C(sp³)–H bond functionalization of 3,5-dimethyl-4-nitroisoxazoles 4 to substituted o-amino benzaldehydes 5 was developed in excellent yields. Isoxazolyl aryl ethanones 7 have been synthesized from isoxazolyl aryl ethanol synthon 6. Furthermore, utilizing the later as synthons for IL promoted Friedlander synthesis of highly functionalized isoxazole substituted quinoline libraries 9. The merit of this synthesis is easily available and economical starting materials, effective utilization of all the reactants, and simple workup procedure. It is noteworthy that ionic liquid used in C(sp³)–H bond functionalization and Friedlander synthesis reactions can be recycled and reused five times without significant decrease in activity.     

Complexation of the cesium cation with 1,3-alternate-25,27-bis(1-octyloxy)calix[4]arene-crown-6

From extraction experiments and γ-activity measurements, the extraction constant corresponding to the equilibrium Cs⁺(aq) + I^?(aq) + 1(nb) ? 1·Cs⁺(nb) + I^?(nb) taking place in the two–phase water–nitrobenzene system (1 = 1,3-alternate-25,27-bis(1-octyloxy)calix[4]arene-crown-6; aq = aqueous phase, nb = nitrobenzene phase) was evaluated as log K _ex (1·Cs⁺, I^?) = 2.9 ± 0.1. Further, the stability constant of the 1·Cs⁺ complex in nitrobenzene saturated with water was calculated for a temperature of 25 °C: log β_nb (1·Cs⁺) = 8.8 ± 0.1. Finally, by using quantum–mechanical DFT calculations, the most probable structure of the resulting cationic complex species 1·Cs⁺ was derived.     

Exchange of halogens in the 3a,6a-diaza-1,4-diphosphapentalene derivatives: Crystal structures of iodides

1,4-Dichloro-3a,6a-diaza-1,4-diphosphapentalene (II) easily exchanges halogen with methyl iodide to form the corresponding 1,4-diiodo derivative (V) in a quantitative yield. The reaction of compound II with diiodine (1 equiv) affords compound III, the crystal structure of which contains 55% II and 45% V. Under the conditions of iodine excess (1 : 3), a ionic compound (IV) is formed, the crystal of which contains alternating layers consisting of planar networks [I₂I₃]? and heterocyclic cations [DDP–Cl]⁺. For the crystallographic information for compounds III–V, see CIF files CCDC no. 1560 410 (V), 1560 411 (III), and 1560 412 (IV).     

Complexation of the cesium cation with nonactin: extraction and DFT study

From extraction experiments and γ-activity measurements, the extraction constant corresponding to the equilibrium Cs⁺(aq) + A^?(aq) + 1(nb) ? 1·Cs⁺(nb) + A^?(nb) taking place in the two-phase water–nitrobenzene system (A^? = picrate, 1 = nonactin; aq = aqueous phase, nb = nitrobenzene phase) was evaluated as log K _ex (1·Cs⁺,A^?) = 2.8 ± 0.1. Further, the stability constant of the 1·Cs⁺ complex in nitrobenzene saturated with water was calculated for a temperature of 25 °C: log β _nb (1·Cs⁺) = 4.7 ± 0.1. Finally, by using quantum–mechanical DFT calculations, the most probable structure of the resulting cationic complex species 1·Cs⁺ was derived.     

Structure of binuclear platinum(III) acetamidate complexes in solutions as probed by <Superscript>195</Superscript>Pt, <Superscript>13</Superscript>C,and <Superscript>1</Superscript>H NMR spectroscopy

¹⁹⁵Pt, ¹H, and ¹³C NMR spectroscopy was used to study the structure of binuclear platinum(III) acetamidate complexes with 1,10-phenanthroline and 2,2′-bipyridine ligands [Pt₂(phen)₂(acam)₄](NO₃)₂ (1) and [Pt₂(bipy)₂(acam)₄](NO₃)₂ (2) in aqueous solutions. The ¹⁹⁵Pt NMR spectra of solutions of complexes 1 and 2 in D₂O exhibit two signals with satellites due to the ¹⁹⁵Pt–¹⁹⁵Pt spin-spin coupling (¹ J(Pt–Pt) ≈ 6345 Hz), whereas their ¹H and ¹³C NMR spectra contain four sets of signals for the protons and the carbon atoms of the heterocyclic and acetamidate ligands. The signals were assigned using the COSY, NOESY, and HSQC/ HMBC experiments and comparing the coordination shifts of the signals for the protons of heterocycles. These data allowed us to draw a conclusion that binuclear complexes 1 and 2 in solution have a head-to-head structure with nonequivalent platinum(III) atoms (coordination cores PtN₅ and PtN₃O₂), the axial-equatorial coordination of the bidentate heterocyclic molecules, and two bridging and two terminal acetamidate ligands.     

Features of self-organization of highly dilute solutions of (<Emphasis Type="Italic">S</Emphasis>)-, (<Emphasis Type="Italic">R</Emphasis>)-, and (<Emphasis Type="Italic">SR</Emphasis>)-methionines and related carbamides and glycolurils

Aqueous solutions of (S)-, (R)-, and (SR)-methionines (1–3); carbamide (4); (S)-, (R)-, and (SR)-N-carbamoylmethionines (5–7); glycoluril (8); and glycolurils containing (S)and (R)-methionine moieties (9 and 10) kept under natural and hypoelectromagnetic conditions were studied in comparison by a complex of physicochemical methods (dynamic and electrophoretic light scattering, conductometry, pH-metry, and dielcometry). The process of selforganization and the properties of dilute solutions (1.0?10^–15–10^–1 mol L^–1) of compounds 1–10 was shown for the first time to depend substantially on the structure of the solute and configuration of methionine (Met) enantiomers. In the series 1–3, the greatest ability to self-organization is observed for solutions of (SR)-Met in which supramolecular domains (1.0?10^–5–1.0?10^–1 mol L^–1) and nanoassociates (1.0?10^–11–1.0?10^–8 mol L^–1) are formed. The formation of nanoassociates in a concentration range of 1.0?10^–12–1.0?10^–6 mol L^–1 can be responsible for the appearance of nonmonotonic concentration dependences of the physicochemical properties of solutions of N-carbamoylmethionines 5–7, whereas the physicochemical properties are more pronounced in solution of (S)-N-carbamoylmethionine 5 than in solutions of 6 and 7. The strongest influence of the configuration of the Met enantiomer on the ability of solution to self-organization was revealed in a series of glycolurils 9, 10: solutions of 9 with the (S)-Met moiety are disperse systems in which nanoassociates are formed in a range of 1.0?10^–15–1.0?10^–5 mol L^–1, whereas in solutions of 10 with the (R)-Met fragment the ability to self-organization in the low-concentration range is absent.     

Complexation of the cesium cation with lithium ionophore VIII: extraction and DFT study

From extraction experiments and γ-activity measurements, the extraction constant corresponding to the equilibrium Cs⁺(aq) + 1·Na ⁺ (nb) = 1·Cs⁺(nb) + Na⁺(aq) taking place in the two-phase water-nitrobenzene system (1 = lithium ionophore VIII; aq = aqueous phase, nb = nitrobenzene phase) was evaluated as log K _ex (Cs⁺, 1·Na⁺) = ?0.5 ± 0.1. Further, the stability constant of the 1·Cs⁺ complex in nitrobenzene saturated with water was calculated for a temperature of 25 °C: log β _nb (1·Cs⁺) = 4.8 ± 0.2. Finally, by using quantum mechanical DFT calculations, the most probable structure of the cationic complex species 1·Cs⁺ was derived. In the resulting complex, the “central” cation Cs⁺ is bound by six bond interactions to the corresponding six oxygen atoms of the parent ligand 1.     

Two novel coordination polymers: Synthesis,structure, luminescent properties,and selective sensing of Cu<Superscript>2+</Superscript> and Mn<Superscript>2+</Superscript> ions

Two novel coordination polymers, namely {[Co(Ttac)_0.5(1,4-Bib)(H₂O)] · H₂O}_n (I) and {[La(HTtac)₂(2H₂O)] · H₂O}n (II) (H4Ttac = 4,5-di(3'-carboxylphenyl)-phthalic acid, 1,4-Bib = 1,4-bis(1-imidazoly) benzene), have been designed and successfully prepared via hydrothermal process, and characterized by elemental analyses, IR spectroscopy, and single crystal X-ray diffraction (CIF files CCDC nos. 1039298 (I), 1039300 (II)). Structural analysis reveals that the H₄Ttac ligands adopt different coordination modes in the as-synthesized I and II, and thus give rise to the targeted coordination polymers with different configurations. It is worth mentioning that, coordination polymer I is assembled from low-dimensional structures into three-dimensional (3D) via π···π stacking interactions, while three-dimensional coordination polymer II is formed by covalent bonds. Luminescent properties of coordination polymer II have been studied at ambient temperature. Significantly, luminescent measurement indicates that coordination polymer II may be acted as potential luminescent recognition sensors towards Cu²⁺ and Mn²⁺ ions.     

Paramagnetic Cu<Superscript>II</Superscript> complexes with 1-(hetarylmethyl)silatranes

The structures of paramagnetic complexes CuCl₂?L with L = HetCH₂Si(OCH₂CH₂)₃N [Het = pyrrol-1-yl (1), indol-1-yl (2), carbazol-9-yl (3), imidazole-1-yl (4), 3,5-dimethylpyrazol-1-yl (5), 1,2,4-triazol-1-yl (6), benzimidazol-1-yl (7), and 1,2,3-benzotriazol-1-yl (8)] were studied by the ESR and quantum chemical methods in terms of the density functional theory (DFT) approximation. The difference in structures of complexes CuCl₂?1—CuCl₂?8 is mainly determined by the nature of the five-membered heterocycle. The ESR spectra at room temperature are typical of the mononuclear complexes of Cu^II of axial symmetry with various types of distortions. In complexes CuCl₂?1—CuCl₂?3, narrow symmetric signals of zero-valent copper are recorded. These signals remain in the spectra for at least six months, which can characterize them as efficient stabilizing matrices of nanoparticles.     

Theoretical study on the ion–molecule reaction of HCN<Superscript>+</Superscript> with NH<Subscript>3</Subscript>

A detailed theoretical study is carried out at the B3LYP/6-311G(d,p) and CCSD(T)/6-311++G(3df,2pd) (single-point) levels as an attempt to investigate the mechanism of the little understand ion–molecule reaction between HCN⁺ and NH₃. Various possible reaction pathways are considered. It is shown that six dissociation products P ₁ (NH₃ ⁺ + HCN), P ₂ (NH₄ ⁺ + CN), P ₃ (NH₃ ⁺ + HNC), P ₉ (HCNH⁺ + NH₂) P ₁₀ (NCNH₃ ⁺ + H), and P ₁₂ (HNCNH₂ ⁺ + H) are both thermodynamically and kinetically feasible. Among these products, P ₁ is the most competitive product with predominant abundance. P ₃ and P ₉ may be the second feasible products with comparable yields. P ₁₂ may be the least possible product followed by the almost negligible P ₂ and P ₁₀ . Because the isomers and transition states involved in the HCN⁺ + NH₃ reaction all lie below the reactant, the title reaction is expected to be rapid, which is consistent with the measured large rate constant in experiment. The title reaction may have a potential relevance in Titan’s atmosphere, where the temperature is very low. Furthermore, our calculated results are compared with the previous experimental findings.     

Synthesis and Characterization of New Os<Subscript>2</Subscript><Superscript>5+</Superscript> and Os<Subscript>2</Subscript><Superscript>6+</Superscript> Azido Complexes

Reaction of Os₂(OAc)₄Cl₂ with an excess of HDPhF (HDPhF = N,N′-diphenylformamidine) gives a high yield of Os₂(DPhF)₄Cl₂ (1), which can be converted to its azido analog, Os₂(DPhF)₄(N₃)₂ (3), by treatment with NaN₃. We report a major improvement on the preparation of Os₂(chp)₄Cl (2; Hchp = 2-chloro-6-hydroxypyridine) by synthesizing the compound in the reducing solvent ethanol. Reaction of 2 with NaN₃ affords the azido complex Os₂(chp)₄N₃ (4). Compound 3 has been examined by X-ray crystallography, and has an Os–Os bond distance of 2.45 Å, suggesting a (π*)² ground state for the molecule.     

Synthesis,characterization and extraction properties of calix[4]crown with amine units and study of its complexes with Cu(II)

In this work, we have focused on the synthesis of p-tert-butyl calix[4]crown with amine units (H ₃ L) as a class of selective receptors for metal ions. The macrocyclic ligand (H ₃ L) with N₂O₇ donors was synthesized via condensation between 1,3-diaminocalix[4]arene and 2-[3-(2-formylphenoxy)-2-hydroxypropoxy] benzaldehyde, followed by reduction of the Schiff base product in situ with sodium borohydride, then it was characterized by FT-IR, ¹H NMR and X-ray crystallography. Two Cu(II) complexes were prepared from the reaction of H ₃ L with Cu(II) salts (CuX₂, X = ClO₄ ^? and Cl^?). FT-IR, UV–Vis, elemental analysis, molar conductivity and cyclic voltammetry techniques were used for study and characterization of these complexes. On the basis of liquid–liquid extraction experiments, ligand H ₃ L indicated good affinity toward Pb²⁺ and Cu²⁺.     

Importance of halide involving interactions at Hoogsteen sites in supramolecular architectures of some coordination metal complexes of N<Superscript>6</Superscript>-benzyl/furfuryl adenine

Background

Most of the benzyladenine and furfuryladenine derivatives inhibit tumor/cancer cell growth; their toxicity is lesser than the compounds used for the treatment of cancer now-a-days. Many cytokinin derivatives are tested for anticancer activity.

Results

A series of transition metal complexes containing N⁶-benzyl/furfuryl aminopurines of formula [Mn(FAH)₂(H₂O)(Cl₃)]₂.Cl₂(1), [Co(FAH)2(H₂O)(Cl₃)]₂.Cl₂(2), [Co(FAH)₂(Cl₄)]_{2 .}[Co(FAH)₂(H₃O)(Cl₃)].Cl₂(3), [Ni(FAH)₂(H₂O)(Cl₃)]₂.Cl_2. (H2O) (4), [Zn(BAH)Br₃] (5) and [Cd₂(BAH)₂(μ-Br)₄Br₂]_n(6) (where BAH and FAH benzyladeninium and furfuryladeninium cations respectively) have been synthesized and characterized. Crystal structures of (1-4) have similar distorted octahedral coordination geometry, while (5) and (6) have distorted tetrahedral geometry and octahedral geometries respectively. In (1-4) two halide ions and two cytokinin cations (BAH⁺/FAH⁺) are laterally coordinated to the metal ion. A water molecule and a halide ion are axially coordinated. But the coordination sphere of (5) consists of N7 coordinated benzyladeninium ion and three halide ions. The complex (6) is a coordination polymer bridged by bromide anions. A common notable feature in (1-4) is the presence of one or more lattice chloride anions. They help in a chain formation by N-H…Cl halide involving hydrogen bonding interactions in between the Hoogsteen site hydrogen.

Conclusions

The observed crystal structures emphasize the role of the halide ions in developing the supramolecular architectures by halide involving hydrogen bonding interactions. Also most of the reported cobalt cytokinin complexes possess tetrahedral coordination geometry, but some cobalt complexes have distorted octahedral coordination geometry, which are discussed and compared.

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Graphical Abstract Supramolecular architectures of some coordination metal complexes of N6-benzyl/furfuryl adenine.

     

New catecholate complexes of triphenylantimony(V) based on 6-iminomethyl-3,5-di-<Emphasis Type="Italic">tert</Emphasis>-butylpyrocatechols N-functionalized by the aniline or phenol group

The following new triphenylantimony(V) catecholate complexes bearing the protonated imine group are synthesized from the new sterically hindered 3,5-di-tert-butylpyrocatechols (6-(CH=N-o-(C₆H₄–NH₂))-3,5-Cat)H₂ (H₂L¹) and (6-(CH=N-o-(C₆H₄–OH))-3,5-Cat)H₂ (H₂L²) containing in position 6 the iminomethyl group bonded to the aniline or phenol substituent: (6-(CH=NH⁺-o-(C₆H₄–NH₂))-3,5-Cat)SbPh₃X (X = Br (I), OMe (III)) and (6-(CH=NH⁺-o-(C₆H₄–OH))-3,5-Cat)SbPh₃X (X = Br (II), OMe (IV)). The molecular structure of complex III · CH ₃ OH in the crystalline state is determined by X-ray diffraction analysis (CIF file CCDC no. 1554694). The electrochemical properties of complexes III and IV are studied by cyclic voltammetry.     

Kinetics and mechanisms of homogeneous catalytic reactions: Part 13. Regioselective reduction of quinoline catalysed by Rh(acac)(CO)[P(<Superscript>t</Superscript>Bu)(CH<Subscript>2</Subscript>CH=CH<Subscript>2</Subscript>)<Subscript>2</Subscript>]

The complex Rh(acac)(CO)[P(^tBu)(CH₂CH=CH₂)₂] (1) proved to be an efficient precatalyst for the regioselective hydrogenation of quinoline (Q) to 1,2,3,4-tetrahydroquinoline (THQ) under mild reaction conditions (125 °C and 4 atm H₂). A kinetic study of this reaction led to the rate law:

$$ r \, = \{ K_{1} k_{2} /(1 \, + \, K_{1} {\text{H}}_{ 2} )\} [{\text{Rh}}][{\text{H}}_{ 2} ]^{2} $$

which becomes

$$ r \, = \, K_{1} k_{2} [{\text{Rh}}][{\text{H}}_{ 2} ]^{2} $$

at hydrogen pressures below 4 atm. The active catalytic species is the cationic complex {Rh(Q)₂(CO)[P(^tBu)(CH₂CH=CH₂)₂]}⁺ (2). The mechanism involves the partial hydrogenation of one coordinated Q of (2) to yield a complex containing a 1,2-dihydroquinoline (DHQ) ligand, {Rh(DHQ)(Q)(CO)[P(^tBu)(CH₂CH=CH₂)₂]}⁺ (3), followed by hydrogenation of the DHQ ligand to give THQ and a coordinatively unsaturated species {Rh(Q)(CO)[P(^tBu)(CH₂CH=CH₂)₂]}⁺ (4); this reaction is considered to be the rate-determining step. Coordination of a new Q molecule to (4) regenerates the active species (2) and restarts the catalytic cycle.

     

Enhancing single-molecule magnet behavior of linear Co<Superscript>II</Superscript>-Dy<Superscript>III</Superscript>Co<Superscript>II</Superscript> complex by introducing bulky diamagnetic moiety

Single-molecule magnets (SMMs) are regarded as promising candidates for ultrahigh-density storage, quantum information processing and molecular spintronics. It is a crucial challenge for chemists to modulate magnetic dynamics of SMMs. Here, we successfully synthesized two 3d-4f polynuclear compounds [Co₂Dy(TTTT^Cl)₂(MeOH)]NO₃·3MeOH (1) and [Co₂Dy(TTTT^Cl)₂ (MeOH)][Co(HTTTT^Cl)](NO₃)₂·2.5MeOH·2H₂O (2), where H₃TTTT^Cl=2,2′,2′′-(((nitrilotris(ethane-2,1-diyl)) tris(azanediyl)) tris(methylene))tris-(4-chlorophenol). On applying the approach by co-crystallization of bulky diamagnetic moiety, the effective energy barrier enhances from 401 K (1) to 536 K (2), which are both among the highest d-f heterometallic SMMs.