Hard Donor Research Articles

Slow Magnetic Relaxation in a Dysprosium Metallocene Complex Bearing Equatorial DyIII−P Bonds

AbstractSingle molecule magnets (SMMs) containing dysprosium‐phosphorus bonding are rare due to great challenges in constructing the bonding between hard lanthanide ions and soft phosphorus donors. Here we successfully isolated a novel mononuclear bis‐Cp* dysprosium compound, Cp*2Dy[η‐CH(PPh2)2]⋅C7H8 (1‐Dy), via the salt metathesis reactions of Cp*2Dy(BPh4) and K[(PPh2)2CH] in THF (Cp*=pentamethylcyclopentadienyl). The magnetic investigations indicate its strong SMM behavior evidenced by the open magnetic hysteresis loops below 6 K and the high effective barrier of 300 cm−1. This could be ascribed to weak dative DyIII−P bonds at equatorial sites in such [Cp2DyX]‐type (X=auxiliary donors) complexes.

Chemistry of Antimony in Radiopharmaceutical Development: Unlocking the Theranostic Potential of Sb Isotopes.

Antimony-119 (119Sb) holds promise for radiopharmaceutical therapy (RPT), emitting short-range Auger and conversion electrons that can deliver cytotoxic radiation on a cellular level. While it has high promise theoretically, experimental validation is necessary for 119Sb in vivo applications. Current 119Sb production and separation methods face robustness and compatibility challenges in radiopharmaceutical synthesis. Limited progress in chelator development hampers targeted experiments with 119Sb. This review compiles literature on the toxicological, biodistribution and redox properties of Sb, along with existing Sb complexes, evaluating their suitability for radiopharmaceuticals. Sb(III) is suggested as the preferred oxidation state for radiopharmaceutical elaboration due to its stability in vivo and lack of skeletal uptake. While Sb complexes with both hard and soft donor atoms can be achieved, Sb thiol complexes offer enhanced stability and compatibility with the desired Sb(III) oxidation state. For 119Sb to find application in RPT, scientists need to make discoveries and advancements in the areas of isotope production, and radiometal chelation. This review aims to guide future research towards harnessing the therapeutic potential of 119Sb in RPT.

2,6-Bis(5-(tert-butyl)-1H-pyrazol-3-yl)pyridine: Effects of the Peripheral Aliphatic Side Chain on the Coordination of Actinides(III) and Lanthanides(III).

To improve our understanding of the interaction mechanism in trivalent lanthanide and actinide complexes, studies with structurally different hard and soft donor ligands are of great interest. For that reason, the coordination chemistry of An(III) and Ln(III) with 2,6-bis(5-(tert-butyl)-1H-pyrazol-3-yl)pyridine (C4-BPP) has been explored. Time-resolved laser fluorescence spectroscopy (TRLFS) studies have revealed the formation of [Cm(C4-BPP)n]3+ (n = 1-3) (log β1' = 7.2 ± 0.4, log β2' = 10.1 ± 0.5, and log β3' = 11.8 ± 0.6) and [Eu(C4-BPP)m]3+ (m = 1-2) (log β1' = 4.9 ± 0.2 and log β2' = 8.0 ± 0.4). The absence of the [Eu(C4-BPP)3]3+ complex shows a more favorable complexation of Cm(III) over that of Eu(III). Additionally, complementary NMR measurements have been conducted to examine the M(III)-N bond in Ln(III) and Am(III) C4-BPP complexes. 15N NMR data have revealed notable differences in the chemical shifts of the coordinating nitrogen atoms between the Am(III) and Ln(III) complexes. In the Am(III) complex, the coordinating nitrogen atoms have shown a shift by 260 ppm, indicating a higher fraction of covalent bonding in the Am(III)-N bond compared with the Ln(III)-N bond. This observation aligns excellently with the differences in the stability constants obtained from TRLFS studies.

Chromene-chromene Schiff base as a fluorescent chemosensor for Th4+ and its application in bioimaging of Caenorhabditis elegans

The manuscript presents the synthesis of a new di-chromene Schiff base (COM-CH) by combining 7-(diethylamino)-2-oxo-2H-chromene-3-carbohydrazide and 4-oxo-4H-chromene-3-carbaldehyde, and its characterization using various analytical techniques. The probe COM-CH functional group contains a hard donor atom that selectively complexes with Th4+ ions. This report investigated COM-CH's sensing ability towards Th4+ chromogenic and fluorogenic methods in ACN: H2O (8:2, v/v) with Th4+ ions. The COM-CH-Th4+ complex was excited at 430 nm, resulting in a bright emission band at 475 nm with a 45 nm Stokes shift. The COM-CH probe demonstrated the highest performance at pH 4.0 to 8.0, with a sensitivity of 18.7 nM. The complex formation of COM-CH with Th4+ was investigated using NMR, FTIR spectrometry, and density functional theory calculations. The COM-CH and Th4+ are bound with 2:1 stoichiometry and an association constant of 1.92 × 108 M−2. The probe's performance enabled the analysis of monazite sand and water samples for Th4+ content. The probe successfully detected Th4+ content in Caenorhabditis elegans, marking the first Th4+ detection in animal models.

Theoretical investigation on the N, O-hybrid donor ligands formed by pyridine rings and ester groups for extraction separation of actinides (III)

The reprocessing of spent nuclear fuel (SNF) is crucial for sustainable nuclear energy development. Efficient extraction and separation of actinides from SNF have garnered significant attention in nuclear research. Mixed extractants, such as Et-Tol-DAPhen, which combine soft and hard donors, exhibit selectivity in extracting transuranium elements. In this study, we investigated three N, O-hybrid donor ligands: L1 (dimethyl pyridine-2,6-dicarboxylate), L2 (dimethyl 1,10-phenanthroline −2,9-dicarboxylate), and L3 (dimethyl [2,2′,6′,2″-terpyridine] −6,6″-dicarboxylate). We systematically compared their bonding ability and separation efficiency with Np(III), Pu(III), Am(III) and Cm(III) using the DFT method. Molecular orbital and electrostatic potential analyses revealed that L2 exhibited strong coordination ability than L1 and L3. Bonding analysis indicated decreased covalency of metal–ligand bonds from Np to Cm, attributed to diminishing involvement of 5f orbitals. Thermodynamic analysis demonstrated that these ligands exhibited good extraction effects and successfully separated Cm from Am and Pu. These findings provide valuable guidance for developing efficient extractants.

Tuning the Alkyl Chain of Nitrilotriacetamide for Selectively Extracting Trivalent Am over Eu Ions.

The successful management and safe disposal of high-level nuclear waste necessitate the efficient separation of actinides (An) from lanthanides (Ln), which has emerged as a crucial prerequisite. Mixed donor ligands incorporating both soft and hard donor atoms have garnered interest in the field of An/Ln separation and purification. One such example is nitrilotriacetamide (NTAamide) derivatives, which have demonstrated selectivity in extracting minor actinide Am(III) ions over Eu(III) ions. Nevertheless, the Am/Eu complexation behavior and selectivity remain underexplored. In the work, a comprehensive and systematic investigation has been conducted for [M(RL)(NO3)3] complexes (M = Am and Eu) utilizing relativistic density functional theory. The NTAamide ligand (RL) is substituted with various alkyl groups, namely, methyl, ethyl, propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl, and n-octyl. Thermodynamic calculations show that the alkyl chain length in NTAamide is capable of tuning the separation selectivity of Am and Eu. Moreover, the differences in calculated free energies between Am and Eu complexes are more negative for R = Bu-Oct than Me-Pr. This indicates that elongation of the alkyl chain can increase the efficiency of selective separation of Am(III) from Eu(III). Based on the quantum theory of atoms in molecules and charge decomposition analyses, it has been observed that the strength of Am-RL bonds is higher than that of Eu-RL bonds. This disparity is attributed to a greater degree of covalency in Am-RL bonds and a higher level of charge transfer from ligands to Am within complexes containing these bonds. Energies of occupied orbitals with the central N character are recognized overall lower for [Am(OctL)(NO3)3] than for [Eu(OctL)(NO3)3], indicative of stronger complexation stability of the former. These results offer valuable insights into the separation mechanism of NTAamide ligands, which can help guide the development of more powerful agents for An/Ln separation in future applications.

A Rigid Linker for Site-Selective Coordination of Transition Metal Cations: Combining an Acetylacetone with a Caged Phosphine

The combination of a soft phosphorus and a hard oxygen donor in the new ligand HacacTRIP leads to excellent site selectivity for the coordination of two different metal cations of matching Pearson character. The deprotonation step required for coordinating the acetylacetone oxygen donor further increases the selectivity. In contrast to most phosphines, the use of the caged phosphatriptycene motif enables a rigid and directional orientation of the phosphorus binding site which is required to form stable coordination network structures. In addition to the synthesis of HacacTRIP, we present its selective coordination. The deprotonated acetylacetone was selectively bound to CuII and FeIII. The solid state structure of the former displays a rare axial coordination of chloroform molecules. The phosphorus donor was selectively coordinated to the monovalent coinage metal cations CuI, AgI, and AuI. The CuI and AgI complexes represent the first examples in which a phosphatriptycene is bound to these metal cations. Heterometallic coordination compounds were characterized with combinations of these two groups. They comprise an oligonuclear CuI/CuII mixed-valence compound in which iodide binds to both CuI and CuII cations and a complex in which acacTRIP- bridges CuII and AuI. In addition to these discrete aggregates, the ligand has been used to link FeIII and AgI into a 2D coordination polymer with unprecedented trigonal planar coordination of three bulky phosphatriptycenes to a cation and resulting honeycomb topology. Its almost regular hexagons underline the desired rigidity of the ditopic acacTRIP- ligand.

Experimental and computational investigation of heteroatom substitution in nucleolytic Cu(II) cyclen complexes for balancing stability and redox activity.

Cu(II) complexes of cyclen-based ligands CuL1-CuL6 were synthesized and characterized. The corresponding ligands L1-L6 comprise different donor sets including S and O atoms. Whereas cyclen (L1) is commercially available, L2-L6 were synthesized according to protocols available in the literature. Cleavage activity of the complexes towards plasmid DNA was tested in the presence and absence of ascorbate as a reducing agent (oxidative vs. hydrolytic cleavage). As previously shown, the substitution of N donor atoms with hard donor O atoms leads to efficient oxidative nucleases, but dissociation of the complex upon reduction. We thus opted for S substitution (soft donors) to stabilize the reduced Cu(I) species. Increasing the S content, however, leads to species that are difficult to reoxidize in order to ensure efficient oxidative DNA cleavage. We are showing by experimental (cyclic voltammetry) and computational means (DFT) that the rational combination of O and S atoms next to two nitrogen donors within the macrocycle (oxathiacyclen complex CuL6) leads to the stabilization of both redox states. The complex thus exhibits the highest oxidative DNA cleavage activity within this family of cyclen-based Cu(II) complexes - without leaching of the metal ion during reduction.

Crystallographic elucidation of an aluminium-bound amido Schiff base chemosensor: a selective turn-on fluorescent chemosensor for Al3+ ions.

We have synthesized a biphenyl-derived two arm-containing amido Schiff base, bis((2-hydroxynaphthalen-1-yl) methylene)-[1,1'-biphenyl]-2,2'-dicarbohydrazide (sensor 1), having hard donors to facilitate chelation with hard metal centers. The crystal structure of sensor 1 reveals that it crystallizes in the monoclinic system with the space group I2/a and shows several types of intra/inter-molecular H-bond interactions, which stabilized the crystal lattice. The sensing property of sensor 1 towards different metal ions has been demonstrated using different analytical techniques. In fact, sensor 1 shows high fluorescence selectivity and sensitivity towards Al3+ ions in aqueous DMF media. Importantly, we have reported the first structurally characterized six-coordinate dinuclear Al3+ complex ([Na(Al2L2)·2H2O·4DMF], complex 1 (where ligand, L = sensor 1). Complex 1 crystallizes in the space group P1̄. X-ray single crystal diffraction studies for complex 1 reveal that each Al3+ ion is hexa-coordinated by four oxygen and two nitrogen atoms from each arm of the two ligands. The sodium ion has penta-coordination in a highly distorted trigonal bipyramidal geometry, surrounded by two μ-bridging naphtholate oxygen atoms and three solvent DMF oxygen atoms. Upon addition of Na2EDTA to complex 1, no spectral change or naked-eye colour change was observed. Furthermore, "test kits" coated with sensor 1 showed successful selective detection of Al3+ ions under UV light.

1,3-C-H bond activation on a transient gallium(I)/isocyanate adduct.

Reaction of NacNacGa with phenylisocyante generates a transient species amenable to unusual 1,3-C-H bond addition of unactivated sp3 C-H and sp2 C-H bonds of substrates featuring a hard donor atom. This reaction proceeds for pyridine oxide, dimethylsulfoxide, and dimethylacetamide, but not for pyridine, cyclohexanone, and ethyl acetate. C-H activation was also not observed for reactions with triethylphosphine oxide but, interestingly, in the presence of this compound isocyanate undergoes self-coupling on Ga(I) with a regioselectivity that is different when carried out in the absence of Et3PO.

Assessing sustainable Lutetium(III) ions adsorption and recovery using novel composite hybrid nanomaterials

Organic ligand-based sustainable composite hybrid material (CMHs) was prepared for the sensitive and selective adsorption of Lutetium (Lu(III)) from waste samples. The hard and soft donor organic ligand of (3-(3-(methoxycarbonyl)benzylidene) hydrazinyl)benzoic acid (MBHB) was immobilized according to the direct approach. The carrier silica and ligand-embedded CMHs were characterized systematically. The adsorption of Lu(III) ion was significantly influenced by the solution pH due to the protonation form of the synthesized organic ligand. However, the slightly acidic pH (4.0) was chosen for sensitive and selective separation and adsorption of Lu(III) ions. The co-existing diverse metal ions were not interfered with during the adsorption of the Lu(III) ion because of the high affinity of the Lu(III) ion to CMHs at the optimum experimental protocol. It was expected that the bond distance between Lu-O was shorter than the other bond length of Lu-N atoms of the organic ligand. The Langmuir adsorption isotherm model was defined according to the morphology of the material and implemented to validate the adsorption isotherms according to the homogeneous ordered structures. The adsorption capacity was 171.76 mg/g as expected due to the high surface area of the CMHs. The adsorbed Lu(III) ion was completely eluted from the CHMs with the eluent of 0.35 M HNO3 and the regenerated material was used in several cycles without significant loss in its original performances. Therefore, it is expected that the ligand-based CMHs may hold huge potential in applications and may be scaled up for commercial applications, including specific separation, adsorption, and recovery of Lu(III) ions from waste samples.

Simpler is better: A heterometallic (Mn-Na) metal organic framework (MOF) with a rare myc topology synthesized from bench chemicals for selective adsorption and separation of organic dyes

A low cost heterometallic (Mn-Na) coordination polymer with rare myc topology is designed and exploited for cationic dye adsorption selectivity and separation. • A low cost new heterometallic ( Mn-Na ) metal organic framework (MOF) is synthesized. • The crystallography reveals presence of two metal ions in the asymmetric unit i.e, Mn and Na. • Topological analysis shows a rare myc topology of the MOF which is very uncommon among the coordination polymers. • The resulting Mn-Na shows excellent selectivity, in the aqueous phase, for adsorption and separation of cationic dye, methylene blue (MB) with adsorption capacity to be 46.22 mg g −1 . • The present material showed excellent structural stability and recyclability with pseudo-second-order kinetics for adsorption. • The plausible mechanism suggests that HSAB concept is responsible for the adsorption process. The present work summarizes the design of a new heterometallic ( Mn-Na ) metal organic framework (MOF) synthesized under solvothermal conditions. The single crystal X-Ray analysis uncovers its composition as [MnNa(HCOO) 3 ] n . The crystallography reveals the presence of two metal ions in the asymmetric unit i.e., Mn and Na which are connected through a bridging formate ligand. Both Mn(II) and Na(I) are coordinated by six oxygen atoms thus forming a distorted octahedral geometry around each metal ion. The HCOO - ligand acts as a bridge to propagate the structure along the three axis resulting in a 3D MOF. Each oxygen of the formate is coordinated to both Mn and Na. Topological analysis shows a rare myc topology of the MOF which is very uncommon among the coordination polymers reported so far. The resulting Mn-Na shows excellent selectivity, in the aqueous phase, for adsorption and separation of cationic dye, methylene blue (MB) with an adsorption capacity to be 46.22 mg g −1 . Moreover, this adsorbent material showed excellent structural stability and recyclability; and the pseudo-second-order kinetics for adsorption. The plausible mechanism suggests that the HSAB concept is responsible for the adsorption process. Hard donors of dye molecules build strong interactions with hard Na + ions embedded in MOF. Thus, the designed MOF is the first example in heterometallic MOF chemistry to show dye adsorption and is established as a simple, easy to prepare and low-cost polymer for environmental protection for future endeavours.

A molecular rotor based ratiometric detection scheme for aluminium ions in water

Aluminium ions play an important role in various biological processes and in the development of methods for its detection has received significant attention recently. Among the reported analytical methods for aluminium ions, fluorescence based detection is considered very advantageous because of its extreme sensitivity and simplicity. However, a large majority of these reported sensor systems for aluminium detection are either based on synthetically involved fluoregenic probes or perform sensing operation via single wavelength based response which makes them susceptible to error due to minute variations in analyte-independent experimental variables. Thus, in the present contribution, we describe a fluorescence ratiometric sensor for the sensitive and selective detection of Al3+ which is based on Al3+ ion dependent modulation of aggregate-monomer equilibrium of Thioflavin-T-Polyacrylic acid system. The molecular rotor dye, Thioflavin-T (ThT), undergoes efficient aggregation, with a distinct emission band, in the presence of a carboxyl laced polyelectrolyte, poly (acrylic acid), PAA. This ThT-PAA monomer-aggregate system undergoes significant modulation in the presence of Al3+ ion due to selective interaction of hard Al3+ ions with hard donors like oxygen containing carboxylate groups. This modulation provides a fluorescence ratiometric response for Al3+ originating from distinct spectroscopic features of ThT monomers and aggregates. Overall, the sensor system provides a selective and sensitive response towards detection of Al3+ with a LOD of 0.9 μM. Importantly, the sensor system is composed of commercially available components and provides freedom from the reliance on time-consuming and tedious protocols required for producing the probe molecules. The ratiometric response provides a robustness to the analytical performance as compared to the system that operates through single wavelength based measurements. We have also demonstrated the sensor system response in real water samples from tap water.

Coordination of a Pyrazole Functionalized Acetylacetone to the Coinage Metal Cations: An Unexpected Packing Similarity and a Trinuclear CuII/AuI Complex

The heteroditopic molecule HacacMePz combines a Pearson hard acetylacetone donor site with a softer trimethylpyrazole and shows site selectivity towards the coinage metal cations. The coordination of the N donor function was achieved towards AgI and AuI, leading to the salt [Ag(HacacMePz)2]PF6 (1) and the neutral complex [AuCl(HacacMePz)] (2). In either case, linear coordination about the coinage metal cation is observed. Interestingly, both complexes crystallize in space group Pbca with similar cell parameters. The two solids do not qualify as isostructural, albeit being closely related in real and reciprocal space. To probe the ligand’s ability for the envisaged synthesis of bimetallic coordination polymers, the mixed-metal CuII/AuI complex [Cu(acacMePzAuCl)2] (3) was obtained. In this mixed-metal oligomer, the central CuII cation adopts a square planar coordination environment with two O,O′-coordinated acacMePz− ligands, whose softer N donor sites are saturated with a AuCl moiety.

Chemistry of tellurium containing macrocycles

Abstract The chemistry of Tellurium containing macrocycles has received great attraction and developed rapidly. Recently inorganic chemists are fascinated by ligands containing macrocycles having tellurium as soft donor and N and O as hard donor atoms. The tellurium atom is more electropositive than carbon due to its large size that resulted in polarisation of Te–C bond. So, tellurium containing macrocycles are explored due to their high reactivity and toxicity. Well-designed macrocycles containing different metals is an interesting field of chemistry as macrocycle with mixed donor atoms can bind two different metal atoms with different nature within the same cavity and thereby ion selectivity increases. Chemistry of macrocycles with tellurium as soft donor atoms also gives rise to very interesting coordination behaviour as addition of Tellurium in macrocycle adds an additional probe (125Te NMR help to monitor their structures in solutions). The chemistry of hard and soft donors in macrocyclic framework makes interesting coordination chemistry and need to be explore. The discussion includes different types of tellurium macrocycles and their chemistry.

Where is the unpaired electron density? A combined experimental and theoretical finding on the geometric and electronic structures of the Co(III) and Mn(IV) complexes of the unsymmetrical non-innocent pincer ONS ligand.

The tridentate pincer ligand [LONS]3- with the ONS donor set was generated in situ by cleaving the disulfane linkage of the pristine redox-active H4Sar(AP/AP) ligand during the complexation reaction with Co(II) and Mn(II) salts in the presence of air and Et3N. X-ray crystal structure analysis of the Co complex (1) and Mn complex (2) revealed that both the complexes were neutral in charge and six-coordinate with the meridional coordination of the two pincer [LONS]n- ligands. The Co ion was in the trivalent state, while the Mn ion was in the tetravalent state. Thus, the generated two pincer [LONS]3- ligands were non-innocent and cumulatively were in trinegative and tetranegative charges for the respective complexes. The intraligand bond distances of the coordinating ligands in each complex were similar, implying the same oxidation/electronic structure of the two ligating units. Variable-temperature magnetic susceptibility measurements revealed an S = 1/2 ground state for each complex. X-band EPR measurements unambiguously established the presence of a ligand-based unpaired electron in complex 1, and in complex 2, the unpaired electron was at the Mn centre. DFT-based theoretical calculations suggested the three-electron oxidation of the two ligating units in complex 1. Two iminosemiquinone radicals were of opposite spins (α-spin and β-spin) and a thiyl radical in either α-spin or β-spin was delocalized between two sulfur atoms. Thus, the antiferromagnetic coupling among the two opposite spins provided an S = 1/2 ground state and resulted in the radical-based EPR spectrum. In complex 2, each ligating pincer unit contained an iminosemiquinone radical that interacted antiferromagnetically with the Mn(IV)-based three unpaired electrons. This rendered a doublet ground state with the residual electron density located at the Mn center.

A bioinspired redox-modulating copper(II)-macrocyclic complex bearing non-steroidal anti-inflammatory drugs with anti-cancer stem cell activity.

Copper(II) coordination compounds have been investigated for their anticancer properties for decades, however, none have reached advanced human clinical trials. The poor translation of copper(II) complexes from in vitro studies to (pre)clinical studies can be attributed to their limited efficacy in animal models, which is largely associated with copper leaching and speciation (in biological fluids). Here we report a biologically stable copper(II) complex based on the active site of Type I Cu electron transport proteins. The copper(II) complex 1 comprises of dithiacyclam (with soft and hard donor atoms) and two diclofenac units, a nonsteriodial anti-inflammatory drug (NSAID). Extensive biophysical and electrochemical studies show that the solid state structure of 1 is preserved in solution and that it can access both copper(I) and copper(II) oxidation states without leaching copper or undergoing speciation (in the presence of a cellular reductant). Cell studies show that 1 kills bulk breast cancer cells and highly resistant breast cancer stem cells (CSCs) at micromolar concentrations, and is significantly less toxic towards a panel of non-cancerous cells. Clinically relevant spheroid studies show that 1 is able to inhibit breast CSC-enriched mammosphere formation to a similar extent as salinomycin, a gold standard anti-CSC agent. Mechanistic studies show that 1 evokes breast CSC death by elevating intracellular reactive oxygen species (ROS) and inhibiting cyclooxygenase-2 (COX-2) activity. The former leads to the activation of stress pathways (JNK and p38), which culminates in caspase-dependent apoptosis. This study reinforces the therapeutic potential of copper(II)-NSAID complexes and provides a bioinspired route to develop stable, ROS-generating copper-based anti-CSC drug candidates.

Selective coordination of coinage metals using orthogonal ligand scaffolds.

Group 11 metal complexes with their ability to form metallophilic interations are widely pursued to develop multifunctional luminescent materials. Heteronuclear coinage metal complexes are promising candidates to tune electronic and optical properties which are not readily accessed by their homometallic congeners. In this review, we present the concept of orthogonal ligands which are rationally designed to access heteronuclear coinage metal complexes and studied in terms of their photophysical properties. Bifunctional ligands containing soft and hard donor atoms have the potential of providing different coordination modes to selectively synthesise heterobimetallic complexes in a predictable manner. This review deals with ligand sets composed of pyridine, bipyridine- or iminopyridine-substituted NHCs featuring C-N coordination modes, phosphine-based N-heterocycles and amidinate ligand scaffolds comprising of P-N functionalities and mixed phosphine-phosphine oxide with P-O donor sites. Therefore, the scope of this perspective is the discussion of heteronuclear coinage metal complexes supported by recently developed bifunctional ligands in terms of their synthesis, coordination geometries and tunability of optical properties when compared to their homometallic analogues.

Facile C-H bond activation on a transient gallium imide.

Reaction of NacNacGa with azide N3SiMe3 results in the generation of a transient imide NacNacGa(NSiMe3) that can cleave unactivated sp3 C-H and sp2 C-H bonds of different substrates, affording gallium amides. Pyridine, cyclohexanone, ethyl acetate, DMSO, and triethylphosphine oxide were activated in this process producing corresponding gallium amides. All new compounds were characterised by multinuclear NMR and X-ray diffraction.

Selective Separation of Am(III)/Eu(III) by the QL-DAPhen Ligand under High Acidity: Extraction, Spectroscopy, and Theoretical Calculations.

Although 1,10-phenanthroline-based ligands have recently shown vast opportunities for the separation of trivalent actinides (Ans(III)) from lanthanides (Lns(III)), the optimization and design of the extractant structure based on the phenanthroline framework remain hotspots for further improving the separation. Following the strategy of hard and soft donor atom combination, for the first time, the quinoline group was attached to the 1,10-phenanthroline skeleton, giving a lipophilic ligand, 2,9-diacyl-bis((3,4-dihydroquinoline-1((2H)-yl)-1),10-phenanthroline (QL-DAPhen)), for Am(III)/Eu(III) separation. In the presence of sodium nitrate, the ligand can effectively extract Am(III) over Eu(III) in HNO3 solution, with the separation factor (SFAm/Eu) ranging from 29 to 44. The coordination chemistry of Eu(III) with QL-DAPhen was investigated by slope analysis, NMR titration, UV-vis titration, Fourier transform infrared spectroscopy, electrospray ionization-mass spectrometry, and theoretical calculations. The experimental results unanimously confirm that the ligand forms both 1:1 and 1:2 complexes with Eu(III), and the stability constants (log β) of each of the two complexes were obtained. Density functional theory calculations show that the Am-N bonds have more covalent characteristics than the Eu-N bonds in the complexes, which reveals the reason why the ligand preferentially bonds with Am(III). Meanwhile, the thermodynamic analysis reveals that the 1:1 complex is more thermodynamically stable than the 1:2 complex. The findings of this work have laid a solid theoretical foundation for the application of phenanthroline-based ligands in the separation of An(III) from practical systems.