Affinity of the Highly Preorganized Ligand PDA (1,10-Phenanthroline-2,9-dicarboxylic acid) for Large Metal Ions of Higher Charge. A Crystallographic and Thermodynamic Study of PDA Complexes of Thorium(IV) and the Uranyl(VI) ion

[4-(2-Aminoethyl)morpholine-κ2N,N']di-bromidocadmium(II): synthesis, crystal structure and Hirshfeld surface analysis

The title compound, [CdBr2(C6H14N2O)], was synthesized upon complexation of 4-(2-aminoethyl)morpholine and cadmium(II) bromide tetra-hydrate at 303 K. It crystallizes as a centrosymmetric dimer, with one cadmium atom, two bromine atoms and one N,N'-bidentate 4-(2-aminoethyl)morpholine ligand in the asymmetric unit. The metal atom is six-coordinated and has a distorted octa-hedral geometry. In the crystal, O⋯Cd inter-actions link the dimers into a polymeric double chain and inter-molecular C-H⋯O hydrogen bonds form R 2 2(6) ring motifs. Further C-H⋯Br and N-H⋯Br hydrogen bonds link the components into a three-dimensional network. As the N-H⋯Br hydrogen bonds are shorter than the C-H⋯Br inter-actions, they have a larger effect on the packing. A Hirshfeld surface analysis reveals that the largest contributions to the packing are from H⋯H (46.1%) and Br⋯H/H⋯Br (38.9%) inter-actions with smaller contributions from the O⋯H/H⋯O (4.7%), Br⋯Cd/Cd⋯Br (4.4%), O⋯Cd/Cd⋯O (3.5%), Br⋯Br (1.1%), Cd⋯H/H⋯Cd (0.9%), Br⋯O/O⋯Br (0.3%) and O⋯N/N⋯O (0.1%) contacts.

Synthesis, crystal structure and Hirshfeld surface analysis of di-acetato-bis-[4-(2-amino-eth-yl)morpholine]cadmium tetra-hydrate

The title coordination compound, [Cd(C2H3O2)2(C6H14N2O)2]·4H2O, was synthesized by mixing 2 moles of 4-(2-amino-eth-yl)morpholine and 1 mole of cadmium acetate in double-distilled water. The Cd atom is octa-hedrally coord-inated by two N,N'-bidentate ligands [4-(2-amino-eth-yl)morpholine] and two trans-located acetate mol-ecules. The Cd atom is located on a center of inversion, whereas the 4-(2-amino-eth-yl)morpholine and four water mol-ecules are adjacent to the acetate mol-ecules. The chair conformation of the morpholine mol-ecules is confirmed. In the crystal, adjacent metal complexes and uncoord-inated water mol-ecules are linked via N-H⋯O and O-H⋯O hydrogen-bonding inter-actions, generating R 2 2(6), R 6 6(16), R 6 6(20) and S 1 1(6) motifs and forming a three-dimensional network. A Hirshfeld surface analysis indicated the contributions of various contacts: H⋯H (71.8%), O⋯H/H⋯O (27.1%), and C⋯H/H⋯C (1.0%).

Unusually Kinetically Inert Monocationic Neptunyl Complex with a Fluorescein-Modified 1,10-Phenanthroline-2,9-dicarboxylate Ligand: Specific Separation and Detection in Gel Electrophoresis

We found a singly charged Np(V)O₂⁺ complex with unprecedented kinetic inertness in aqueous solution, one million times slower than the widely accepted fast kinetics of neptunyl complexes. An inert NpO₂⁺ complex with a fluorescent 1,10-phenanthroline-2,9-dicarboxylate derivative was found by kinetic selection using polyacrylamide gel electrophoresis (PAGE) from a small chemical library. Autoreduction from Np(VI)O₂²⁺ to Np(V)O₂⁺ via complexation was observed. A remarkably small spontaneous dissociation rate constant of 8 × 10^-6 s^-1 (half-life of 23 h) was determined using PAGE. Selective detection of Np(V)O₂⁺ was achieved in PAGE with a detection limit of 68 pmol dm^-3 (17 fg). This system was successfully applied to simulated radioactive waste samples. Our finding that electron-rich NpO₂⁺ forms a uniquely inert complex with no strong electrostatic interaction reveals a new aspect of actinide chemistry for developing a novel separation system of real radioactive material samples.

Theoretical insights into selective extraction of uranium from seawater with tetradentate N,O-mixed donor ligands

The competition of uranium and vanadium ions is a major challenge in extracting uranium from seawater. In-depth exploration of the complexation of uranium and vanadium ions with promising ligands is essential to design highly efficient ligands for selective recovery of uranium. In this work, we systematically explored the uranyl and vanadium extraction complexes with three tetradentate N,O-mixed donor analogues including the rigid backbone ligands 1,10-phenanthroline-2,9-dicarboxylic acid (PDA, L¹) and 5H-cyclopenta[2,1-b:3,4-b']dipyridine-2,8-dicarboxylate acid (L³), as well as the flexible ligand [2,2'-bipyridine]-6,6'-dicarboxylate acid (L²) using density functional theory (DFT). These ligands coordinate to the uranyl cation in a tetradentate fashion, while L¹ and L³ act as tridentate ligands toward VO₂⁺ due to the smaller ionic radius of VO₂⁺ and larger cleft sizes of L¹ and L³. Bonding analyses show that the metal-ligand bonding orbitals of the uranyl complexes [UO₂L(CO₃)]^2-, [UO₂L(OH)]^-, and [UO₂L(H₂O)] mainly arise from the interactions of the U 5f, 6d orbitals and N, O 2p orbitals. Because of the rigid structure and more suitable chelate ring size, the L¹ ligand possesses a stronger complexing ability for uranyl ions than other ligands, while the L³ ligand has weaker binding affinity than L¹ and L². All these ligands prefer to coordinate with the uranyl cation rather than vanadium ion, indicating the selectivity of these ligands to [UO₂(CO₃)₃]^4- over H₂VO₄^- and HVO₄^2- in seawater. This is mainly attributed to the metal ion size-based selectivity and structural preorganization of the ligands. These results demonstrate that the backbone of these ligands affect their extraction behaviors. It is expected that this work might prove useful in designing efficient ligands for uranium extraction from seawater.

Two Ligands of Interest in Recovering Uranium from the Oceans: The Correct Formation Constants of the Uranyl(VI) Cation with 2,2'-Bipyridyl-6,6'-dicarboxylic Acid and 1,10-Phenanthroline-2,9-dicarboxylic Acid

The ligands BDA (2,2'-bipyridyl-6,6'-dicarboxylic acid) and PDA (1,10-phenanthroline-2,9-dicarboxylic acid) are of interest as functional group types for ion-exchange materials for extracting uranium from the oceans, reported in a previous paper for PDA Lashley, M. A. ( Inorg. Chem. 2016 55 10818 10829). Yang, Y. ( Inorg. Chem. 2019, 58, 6064 6074) have published what they claim to be a more accurate result for the formation of the UO₂²⁺/PDA complex of log K₁ = 22.84 compared with our reported value of log K₁ = 16.5, as well as log K₁ = 21.52 for the BDA complex. The determination of log K₁ for the PDA and BDA complexes with the UO₂²⁺ cation was carried out by Yang et al. using a competition reaction between DTPA (diethylenetriamine pentaacetic acid) and BDA or PDA, monitoring the absorbance due to the BDA and PDA ligands. This competition method using absorbance versus pH titrations was developed for determining the formation constants of the complexes of several polypyridyl ligands plus PDA complexes of metal ions, which were too stable for log K determination by competition with protons. A key feature of such titrations is that in the competition reaction, the displacement of the pyridyl donor ligand (e.g., PDA) by the competing ligand (e.g., DTPA), the absorbance spectrum of the displaced pyridyl donor ligand should be observed. Competing ligands used to date have been EDTA (ethylenediamine tetraacetic acid), DTPA, or the hydroxide ion. In the study of Yang et al., no such displaced PDA or BDA was apparent in the absorbance spectra in their titrations so that their reported log K₁ values have no validity. Their log K₁ values are so much higher than log K₁ for the uranyl DTPA complex (∼13.6) that DTPA could not possibly displace BDA or PDA from the uranyl cation, and a competition reaction could not possibly occur. We report the correct value of log K₁ = 15.4 (ionic strength = zero) for the uranyl BDA complex, to illustrate the correct determination of such a constant by a competition reaction between BDA and hydroxide, showing how the characteristic absorbance spectrum for a BDA complex, here the UO₂²⁺ complex, disappears, and the distinctive absorbance spectrum of the free nonprotonated BDA ligand appears as the pH is increased, and BDA is displaced by the hydroxide ion.

Spectroscopic evaluation of UVI-cement mineral interactions: ettringite and hydrotalcite

Portland cement based grouts used for radioactive waste immobilization contain high replacement levels of supplementary cementitious materials, including blast-furnace slag and fly ash. The minerals formed upon hydration of these cements may have capacity for binding actinide elements present in radioactive waste. In this work, the minerals ettringite (Ca6Al2(SO4)3(OH)12·26H2O) and hydrotalcite (Mg6Al2(OH)16CO3·4H2O) were selected to investigate the importance of minor cement hydrate phases in sequestering and immobilizing UVI from radioactive waste streams. U LIII-edge X-ray absorption spectroscopy (XAS) was used to probe the UVI coordination environment in contact with these minerals. For the first time, solid-state 27Al magic angle spinning nuclear magnetic resonance (MAS-NMR) spectroscopy was applied to probe the Al coordination environment in these UVI-contacted minerals and make inferences on the UVI coordination, in conjunction with the X-ray spectroscopy analyses. The U LIII-edge XAS analysis of the UVI-contacted ettringite phases found them to be similar (>∼70%) to the uranyl oxyhydroxides present in a mixed becquerelite/metaschoepite mineral. Fitting of the EXAFS region, in combination with 27Al NMR analysis, indicated that a disordered Ca- or Al-bearing UVI secondary phase also formed. For the UVI-contacted hydrotalcite phases, the XAS and 27Al NMR data were interpreted as being similar to uranyl carbonate, that was likely Mg-containing.

[nat/89Zr][Zr(pypa)]: Thermodynamically Stable and Kinetically Inert Binary Nonadentate Complex for Radiopharmaceutical Applications

H₄pypa is a nonadentate nonmacrocyclic chelator, which previously demonstrated high affinity for scandium-44, lutetium-177, and indium-111. Herein, we report the highly stable binary [Zr(pypa)] complex; the nonradioactive complex was synthesized and characterized in detail using high-resolution electrospray-ionization mass spectroscopy (HR-ESI-MS) and various nuclear magnetic resonance spectroscopies (NMR), which revealed C_2v symmetry of the complex. The geometry of [Zr(pypa)] was further detailed via X-ray crystallography and compared with the structure of [Fe(Hpypa)]. Despite a slow complexation rate with an association half-life of 31.4 h at pH 2 and room temperature, the [Zr(pypa)] complex is thermodynamically stable (log K_ML = 38.92, pZr = 39.4). Radiochemical studies demonstrated quantitative radiolabeling achieved at 10 μM chelator concentration within 2 h at 40 °C and pH = 7, antibody-compatible conditions. Of the utmost importance, [⁸⁹Zr][Zr(pypa)] is highly kinetically inert upon challenge with excess EDTA and DFO ligands, superior to [⁸⁹Zr][Zr(DFO)]⁺, and maintains inertness toward human serum.

Complexes of Th(IV) with neutral O-N-N-O hybrid ligands: a thermodynamic and crystallographic study

The thermodynamics of Th(iv) complexes with N,N,N',N'-tetramethyl-2,2'-bipyridine-6,6'-dicarboxamide (TMBiPDA) and N,N,N',N'-tetramethyl-1,10-phenanthroline-2,9-dicarboxamide (TMPhenDA) in CH3OH/10%(v)H2O (CH3OH : H2O = 9 : 1 by volume) were determined by spectrophotometry and calorimetry. The ligand TMBiPDA/TMPhenDA coordinates with the central Th atom by the tetradentate (O-N-N-O) mode, which is validated by 1H NMR in solution and crystallography in the solid. The single crystal X-ray diffraction data show that ten-coordinated thorium coordinates with two ligand molecules and two solvent molecules (water or methanol). Both ThL and ThL2 complexes (L = TMPhenDA or TMBiPDA) were detected in solution. In thermodynamics, the formation of all complexes is driven by both enthalpy and entropy. In a comparison, enthalpy is more favorable to the formation of TMBiPDA complexes, while entropy is more favorable to the formation of TMPhenDA complexes; the entropy advantages of the TMPhenDA complexes override the enthalpy advantages of the corresponding TMBiPDA complexes, giving the TMPhenDA complexes higher stability constants than the TMBiPDA complexes. In crystallography, ligand distortions occur in ThL2 complexes, and TMBiDA distorts more than TMPhenDA does; the Th-O and Th-N bonds involving TMBiPDA are slightly shorter than those involving TMPhenDA.

tBu4octapa-alkyl-NHS for metalloradiopeptide preparation

The peptide is an important class of biological targeting molecule; herein, a new bifunctional octadentate non-macrocyclic H4octapa, tBu4octapa-alkyl-NHS, which is compatible with solid-phase peptide synthesis and thus useful for radiopeptide preparation, has been synthesized. To preserve denticity, the alkyl-N-hydroxylsuccinimide linker was covalently attached to the methylene-carbon on one of the acetate arms, yielding a chiral carbon center. According to density-functional theory (DFT) calculations using [Lu(octapa-alkyl-benzyl-ester)]- as a simulation model, the chirality has minimal effects on the complex geometry; regardless of the S-/R-stereochemistry, DFT calculations revealed two possible geometric isomers, distorted bicapped trigonal antiprism (DBTA) and distorted square antiprism (DSA), due to the asymmetry in the chelator. To evaluate the biological behavior of the new bifunctionalization, two well-studied PSMA (prostate-specific membrane antigen)-targeting peptidomimetics of varying hydrophobicity were chosen as proof-of-principle targeting vector molecules. Radiolabeling both bioconjugates with lutetium-177 was highly efficient at room temperature in 15 min at micromolar chelator concentration pH = 7. Both the in vitro serum challenge and the lanthanum(iii) challenge studies revealed complex lability, and notably, progressive bone accumulation was only observed with the more hydrophobic linker (i.e. H4octapa-alkyl-PSMA617). This in vivo result informs potential alterations exerted by the linker on the complex geometry and stability, with an appropriate biological targeting vector adopted for such evaluations.

Targeted cell imaging properties of a deep red luminescent iridium(iii) complex conjugated with a c-Myc signal peptide

A nuclear localisation sequence (NLS) peptide, PAAKRVKLD, derived from the human c-Myc regulator gene, has been functionalised with a long wavelength (λ ex = 550 nm; λ em = 677 nm) cyclometalated organometallic iridium(iii) complex to give the conjugate Ir-CMYC. Confocal fluorescence microscopy studies on human fibroblast cells imaged after 18-24 h incubation show that Ir-CMYC concentrations of 80-100 μM promote good cell uptake and nuclear localisation, which was confirmed though co-localisation studies using Hoechst 33342. In comparison, a structurally related, photophysically analogous iridium(iii) complex lacking the peptide sequence, Ir-PYR, showed very different biological behaviour, with no evidence of nuclear, lysosomal or autophagic vesicle localisation and significantly increased toxicity to the cells at concentrations >10 μM that induced mitochondrial dysfunction. Supporting UV-visible and circular dichroism spectroscopic studies show that Ir-PYR and Ir-CMYC display similarly low affinities for DNA (ca. 103 M-1), consistent with electrostatic binding. Therefore the translocation and nuclear uptake properties of Ir-CMYC are attributed to the presence of the PAAKRVKLD nuclear localisation sequence in this complex.

Effects of Diluents on the Separation of Minor Actinides from Lanthanides with Tetradodecyl-1,10-phenanthroline-2,9-diamide from Nitric Acid Medium

To investigate the effective separation of actinides (Ans) from lanthanides (Lns), single-stage batch extraction experiments were performed with a novel extractant, tetradodecyl-1,10-phenanthroline-2,9-diamide (TDdPTDA) with various diluents such as 3-nitrobenzotrifluoride (F-3), nitrobenzene, and n-dodecane for Am, Cm, and Lns. The extraction kinetics with TDdPTDA was rapid enough to perform continuous extraction experiments using mixer-settler extractors. The slopes of the distribution ratio versus the TDdPTDA concentration and the distribution ratio versus the nitric acid concentration were similar for F-3 and nitrobenzene systems, but different from the n-dodecane system. These differences were attributed to the characteristics of the diluents. This study revealed high distribution ratios of Am (DAm) and Cm (DCm) for TDdPTDA, with the high separation factors (SFs) of Am from Lns enough for their separation.

Oxygen and peroxide bridged uranyl(vi) dimers bearing tetradentate hybrid ligands: supramolecular self-assembly and generation pathway

Crystals of U(vi) complexes with N,N,N′,N′-tetramethyl-2,2′-bipyridine-6,6′-dicarboxamide and N,N,N′,N′-tetramethyl-1,10-phenanthroline-2,9-dicarboxamide were obtained under variable reaction conditions, and the structures were determined by single-crystal X-ray diffraction.

The impact of alicyclic substituents on the extraction ability of new family of 1,10-phenanthroline-2,9-diamides

Some unexpected “structure–extraction properties” patterns were found for new family of 1,10-phenanthroline-2,9-diamide derived ligands.

On the preferences of five-membered chelate rings in coordination chemistry: insights from the Cambridge Structural Database and theoretical calculations

The purpose of this review is to give an overview of three important N-bidentate ligands: 1,10-phenanthroline (phen), 2,2'-bipyridine (bpy), and ethylenediamine (en). We have not attempted to be comprehensive because of the huge amount of activity being done in coordination chemistry using these ligands. Instead we present a full structural and geometrical study by using the Cambridge Structural Database (CSD) combined with theoretical calculations that allow us to parameterize their coordinating properties and ability to coordinate to transition and non-transition metals. More importantly, we illustrate that upon coordination and formation of the five-membered chelate ring, these ligands are able to adapt themselves to the requirements of the different metals by changing the MN distances and NMN angles. Therefore, a redefinition of the preferences of these ligands to metals with large ionic radii is needed. Finally, we will present some facts about the participation of these ligands in inorganic-organic hybrids (IOHs) based on Keggin polyoxometalates (POMs).

Novel enterobactin analogues as potential therapeutic chelating agents: Synthesis, thermodynamic and antioxidant studies

A series of novel hexadentate enterobactin analogues, which contain three catechol chelating moieties attached to different molecular scaffolds with flexible alkyl chain lengths, were prepared. The solution thermodynamic stabilities of the complexes with uranyl, ferric(III), and zinc(II) ions were then investigated. The hexadentate ligands demonstrate effective binding ability to uranyl ion, and the average uranyl affinities are two orders of magnitude higher than 2,3-dihydroxy-N¹,N⁴-bis[(1,2-hydroxypyridinone-6-carboxamide)ethyl]terephthalamide [TMA(2Li-1,2-HOPO)₂] ligand with similar denticity. The high affinity of hexadentate ligands could be due to the presence of the flexible scaffold, which favors the geometric agreement between the ligand and the uranyl coordination preference. The hexadentate ligands also exhibit higher antiradical efficiency than butylated hydroxyanisole (BHA). These results provide a basis for further studies on the potential applications of hexadentate ligands as therapeutic chelating agents.

Molecular design of a novel ligand for Menshutkin complexation of Bi(iii) from aqueous acidic copper sulfate electrolyte solutions and experimental investigations

A novel silica functionalised phen–arene adsorbent exhibits reversible and highly selective adsorption of Bi(iii) over Cu(ii) ions by Menshutkin complexation from an aqueous acidic copper electrolyte solution.

A new linear bismuth coordination polymer based on 1,10-phenanthroline-2,9-dicarboxylic acid: ionothermal synthesis, crystal structure and fluorescence properties

A new linear bismuth(III) coordination polymer, catena-poly[[chloridobismuth(III)]-μ3-1,10-phenanthroline-2,9-dicarboxylato-κ(6)O(2):O(2),N(1),N(10),O(9):O(9)], [Bi(C14H6N2O4)Cl]n, has been obtained by an ionothermal method and characterized by elemental analysis, energy-dispersive X-ray spectroscopy, IR spectroscopy, thermal stability studies and single-crystal X-ray diffraction. The structure is constructed by Bi(C14H6N2O4)Cl fragments in which each Bi(III) centre is seven-coordinated by one Cl atom, four O atoms and two N atoms. The coordination geometry of the Bi(III) cation is distorted pentagonal-bipyramidal (BiO4N2Cl), with one bridging carboxylate O atom and one Cl atom located in the axial positions. The Bi(C14H6N2O4)Cl fragments are further extended into a one-dimensional linear polymeric structure via subsequent but different centres of symmetry (bridging carboxylate O atoms). Neighbouring linear chains are assembled via weak C-H···O and C-H···Cl hydrogen bonds, forming a three-dimensional supramolecular architecture. Intermolecular π-π stacking interactions are observed, with centroid-to-centroid distances of 3.678 (4) Å, which further stabilize the structure. In addition, the solid-state fluorescence properties of the title coordination polymer were investigated.

Quantum chemistry study of uranium(VI), neptunium(V), and plutonium(IV,VI) complexes with preorganized tetradentate phenanthrolineamide ligands

The preorganized tetradentate 2,9-diamido-1,10-phenanthroline ligand with hard-soft donors combined in the same molecule has been found to possess high selectivity toward actinides in an acidic aqueous solution. In this work, density functional theory (DFT) coupled with the quasi-relativistic small-core pseudopotential method was used to investigate the structures, bonding nature, and thermodynamic behavior of uranium(VI), neptunium(V), and plutonium(IV,VI) with phenanthrolineamides. Theoretical optimization shows that Et-Tol-DAPhen and Et-Et-DAPhen ligands are both coordinated with actinides in a tetradentate chelating mode through two N donors of the phenanthroline moiety and two O donors of the amide moieties. It is found that [AnO2L(NO3)](n+) (An = U(VI), Np(V), Pu(VI); n = 0, 1) and PuL(NO3)4 are the main 1:1 complexes. With respect to 1:2 complexes, the reaction [Pu(H2O)9](4+)(aq) + 2L(org) + 2NO3(-)(aq) → [PuL2(NO3)2](2+)(org) + 9H2O(aq) might be another probable extraction mechanism for Pu(IV). From the viewpoint of energy, the phenanthrolineamides extract actinides in the order of Pu(IV) > U(VI) > Pu(VI) > Np(V), which agrees well with the experimental results. Additionally, all of the thermodynamic reactions are more energetically favorable for the Et-Tol-DAPhen ligand than the Et-Et-DAPhen ligand, indicating that substitution of one ethyl group with one tolyl group can enhance the complexation abilities toward actinide cations (anomalous aryl strengthening).

Specific chiral sensing of amino acids using induced circularly polarized luminescence of bis(diimine)dicarboxylic acid europium(III) complexes

The circularly polarized luminescence (CPL) from [Eu(pda)2](-) (pda = 1,10-phenanthroline-2,9-dicarboxylic acid) and [Eu(bda)2](-) (bda = 2,2'-bipyridine-6,6'-dicarboxylic acid) in aqueous solutions containing various amino acids was investigated. The europium(III) complexes exhibited bright-red luminescence assignable to the f-f transition of the Eu(III) ion when irradiated with UV light. Although the luminescence was not circularly polarized in the solid state or in aqueous solutions, in accordance with the achiral crystal structure, the complexes exhibited detectable induced CPL (iCPL) in aqueous solutions containing chiral amino acids. In the presence of L-pyrrolidonecarboxylic acid, both [Eu(pda)2](-) and [Eu(bda)2](-) showed similar iCPL intensity (glum ∼ 0.03 for the (5)D0 → (7)F1 transition at 1 mol·dm(-3) of the amino acid). On the other hand, in the presence of L-histidine or L-arginine, [Eu(pda)2](-) exhibited intense CPL (glum ∼ 0.08 for the (5)D0 → (7)F1 transition at 0.10 mol·dm(-3) of the amino acid), whereas quite weak CPL was observed for [Eu(bda)2](-) under the same conditions (glum < 0.01). On the basis of analysis of the iCPL intensities in the presence of 12 amino acids, [Eu(pda)2](-) was found to be a good chiral CPL probe with high sensitivity (about 10(-2) mol·dm(-3)) and high selectivity for L-histidine at pH 3 and for L-arginine at pH 7. The mechanism of iCPL was evaluated by analysis of the fine structures in the luminescence spectra and the amino acid concentration dependence of glum. For the [Eu(pda)2](-)-histidine/arginine systems, the europium(III) complexes possess coordination structures similar to that in the crystal with slight distortion to form a chiral structure due to specific interaction with two zwitterionic amino acids. This mechanism was in stark contrast to that of the europium(III) complex-pyrrolidonecarboxylic acid system in which one amino acid coordinates to the Eu(III) ion to yield an achiral coordination structure.

High selectivity towards small copper ions by a preorganized phenanthroline-derived tetradentate ligand and new insight into the complexation mechanism

A preorganized tetradentate phenanthroline-derived amide ligand was found to show high selectivity towards small copper ions.

Bis(ethanamidinium) (1,10-phen-an-thro-line-2,9-dicarboxyl-ato)manganate(II) hepta-hydrate

In the title complex, (C₂H₇N₂)₂[Mn(C₁₄H₆N₂O₄)₂]·7H₂O, the Mn^II atom is coordinated by four N atoms and four O atoms from two 1,10-phenanthroline-2,9-dicarboxyl­ate ligands in a distorted dodeca­hedral geometry. The double negative charge is balanced by two ethanamidinium cations. A three-dimensional supra­molecular structure is formed through N—H⋯O and O—H⋯O hydrogen bonds and π–π stacking inter­actions [centroid–centroid distance = 3.553 (2) Å].