Reaction Of Ln Research Articles

Two rhombic-shaped Ln4 clusters for efficiently catalyzing CO2 cycloaddition and knoevenagel condensation

Two Ln4 clusters with the formula of [Ln4(acac)4(µ3OH)2(L)6]·xCH3CN (Ln=Sm (1), Yb (2)) were synthesized through the reaction of Ln(acac)3·2H2O (Hacac = acetylacetone) with the bidentate flexible ligand 5-benzylidene-1,5-dihydroquinolin-8-ol. X-ray diffraction studies indicate that clusters 1 and 2 are isostructural and processes a rhombic-shaped Ln4 core. The coordination geometry of each Ln(III) ion is characterized as a distorted square antiprism. Notably, clusters 1 and 2 exhibit outstanding catalytic performance for the cycloaddition of CO2 with epoxides and for Knoevenagel condensation under mild conditions.

Synthesis and Characterization of Diacylthiourea and Diacylthioureato Cu(I) Complexes

A series of six disubstituted diacylthioureas 1,3‐ and 1,4‐C6H4[C(O)NHC(S)NR1R2]2 (L1‐6) were synthesized with varied Rn substituents (R1 = R2 = Et for L1‐2; R1 = R2 = Bn for L3‐4; R1 = iPr and R2 = Ph for L5 (1) and L6 (2)). Treatment of Ln with Cu(I) halide precursors CuX(PPh3)3 (X = Cl, Br, I) produced the discrete binuclear adducts Ln[CuX(PPh3)2]2 (3‐11 and 14‐16; n = 1‐3 and 6) by binding to Cu(I) centres via the monodentate‐S mode. In contrast, L4 and L5 yielded only the chloride products of binuclear L4[CuCl(PPh3)2]2 (12) and mononuclear L5CuCl(PPh3)2 (13), respectively, with one S arm in the latter remaining dangling, while bromide or iodide analogues were not available for L4 and L5, possibly due to the steric hindrance imposed by larger halide anions or bulky isopropyl substituents. The reactions of Ln with nitrate [Cu(NO3)(PPh3)2]led to the double‐deprotonation of ligand protons to generate dianions Ln' (1,3‐/1,4‐C6H4[C(O)NC(S)NR1R2]22‐) and led to the consequent formation of binuclear diacylthioureato Cu(I) complexes Ln'[Cu(PPh3)2]2 (n=1 (17), 2 (18), 4 (19)) via the κ‐O,S‐bidentate mode. The obtained ligands and complexes were spectroscopically and structurally characterized. These Cu(I) products (3‐19) were experimentally used as catalysts for the oxidation of 1‐phenylethanol.

Syntheses and properties of seven 3,4-dichlorobenzoate-based zinc-rare earth heterometallic complexes containing a field-induced Zn(II)-Dy(III)-Dy(III)-Zn(II) single-molecule magnet

Under solvothermal conditions of CH3CH2OH and H2O, a series of 3d-4f heterometallic complexes [Ln2Zn2(3,4-DCB)10(2,2′-bpy)2] [Ln = Sm (1), Eu (2), Gd (3), Tb (4), Dy (5), Er (6) and Yb (7), 3,4-DCB = 3,4-dichlorobenzoic acid, 2,2′-bpy = 2,2′-bipyridine] were synthesized by the reactions of Ln(NO3)3·6H2O, Zn(NO3)2·6H2O, 3,4-HDCB, 2,2′-bpy and NaOH. These complexes were characterized by single crystal X-ray diffraction, powder X-ray diffraction (PXRD), Fourier transform infrared (FT-IR) spectroscopy and thermogravimetric analysis (TGA) and differential thermo analysis (DTA). Complexes 1–7 show two types of different zero-dimensional (0D) structures although they have the same molecular formula. Complexes 1–5 are isomorphic, and complexes 6 and 7 are isomorphic. In 1–7, linear tetranuclear clusters are formed from 3,4-DCB connecting Ln(III) and Zn(II). They can be expanded into one-dimensional (1D) supramolecular chains or two-dimensional (2D) supramolecular layers by the intermolecular π–π interactions. The photoluminescent properties of 1, 2, 4 and 5 and the magnetic properties of 3–7 were studied in detail. Complex 5 exhibits an obvious field-induced single-molecule magnet behavior with a Ueff value of approximately 24 K.

Synthesis, structure, photoluminescence and magnetism of a series of cobalt‐lanthanide heterometallic complexes originated from 2,3‐dichlorobenzoate and 1,10‐phenanthroline

AbstractA series of 3d–4f heterometallic complexes, namely [Ln2Co2(2,3‐DCB)10(phen)2] [Ln=Nd (1), Sm (2), Eu (3), Gd (4), Tb (5), Dy (6), Er (7)], were obtained through the self‐assembly reactions of Ln(NO3)3 ⋅ nH2O, Co(NO3)2 ⋅ 6H2O, 2,3‐dichlorobenzoic acid (2,3‐HDCB), NaOH and 1,10‐phenanthroline (phen) under solvothermal conditions. Their crystal structures were determined by single‐crystal X‐ray diffraction. They were also characterized by elemental analysis, FT‐IR, powder X‐ray diffraction (PXRD) and thermogravimetric analysis (TGA) and differential thermoanalysis (DTA). These seven complexes have the same molecular formula but different crystal structures. Complexes 1–3, 4 and 5 as well as 6 and 7 are crystallographically isomorphous, respectively. They all exhibit zero‐dimensional (0D) linear tetranuclear cluster structures. These 0D linear tetranuclear clusters can be further connected into a two‐dimensional (2D) supramolecular network via the extensive intermolecular π–π interactions between 2,3‐DCB and phen. The photoluminescent properties of 3, 5 and 6 and the magnetic properties of 1–2 and 4–7 were investigated. Complex 6 shows a slow magnetic relaxation behavior.

Interesting chemical and physical features of the products of the reactions between trivalent lanthanoids and a tetradentate Schiff base derived from cyclohexane-1,2-diamine.

The initial use of a tetradentate Schiff base (LH2) derived from the 2 : 1 condensation between 2-hydroxyacetophenone and cyclohexane-1,2-diamine in 4f-metal chemistry is described. The 1 : 2 reaction of Ln(NO3)3·xH2O (Ln = lanthanoid or yttrium) and LH2 in MeOH/CH2Cl2 has provided access to isostructural complexes [Ln(NO3)3(L'H2)(MeOH)] in moderate to good yields. Surprisingly, the products contain the corresponding Schiff base ligand L'H2 possessing six aliphatic -CH2- groups instead of the -CH-(CH2)4-CH- unit of the cyclohexane ring, i.e. an unusual ring-opening of the latter has occurred. A mechanism for this LnIII-assisted/promoted LH2 → L'H2 transformation has been proposed assuming transient LnII species and a second LH2 molecule as the H2 source for the reduction of the cyclohexane moiety. DFT calculations provide strong evidence for the great thermodynamic stability of the products in comparison with analogous complexes containing the original intact ligand. The structures of the PrIII, SmIII, GdIII, TbIII, and HoIII complexes have been determined by single-crystal X-ray crystallography. The 9-coordinate LnIII centre in the molecules is bound to six oxygen atoms from the three bidentate chelating nitrato groups, two oxygen atoms that belong to the bidentate chelating organic ligand, and one oxygen atom from the coordinated MeOH group. In the overall neutral bis(zwitterionic) L'H2 ligand, the acidic H atoms are clearly located on the imino nitrogen atoms and this results in the formation of an unusual 16-membered chelating ring. The coordination polyhedra defined by the nine donor atoms around the 4f-metal-ion centres can be best described as distorted, spherical capped square antiprisms. The EuIII, TbIII, and DyIII complexes exhibit LnIII-based luminescence in the visible region, with the coordinated L'H2 molecule acting as the antenna. Ac magnetometry experiments show that the DyIII member of the family behaves as an SIM at zero field and under external dc fields of 0.1 and 0.2 T without the enhancement of the peaks' maxima, suggesting that QTM is not the relaxation path. The GdIII complex behaves, rather unexpectedly, as a SIM with two different magnetic relaxation paths occurring at very close temperatures; this behaviour is tentatively attributed to a very small axial zero-field splitting (D ∼ 0.1 cm-1), which cannot be detected by magnetization or susceptibility experiments. The prospects of the present, first results in the lanthanoid(III)-LH2 chemistry are discussed.

Luminescence, CPL and magnetic properties of 1D enantiopure Ln3+ complexes with (S-) and (R-) α-methoxyphenylacetate ligand.

The reaction of Ln(NO3)2·6H2O (Ln = Eu, Tb, Dy and Sm) with (R)-(-)-α-methoxyphenylacetic acid (R-HMPA) and 1,10-phenanthroline (phen) in EtOH/H2O allows the isolation of 1D chiral compounds of formula [Ln(μ-R-MPA)(R-MPA)2(phen)]n in which Ln = Eu (R-Eu), Tb (R-Tb), Dy (R-Dy) and Sm (R-Sm). The same synthesis by using (S)-(+)-α-methoxyphenylacetic acid (S-HMPA) instead of (R)-(-)-α-methoxyphenylacetic acid allows the isolation of the enantiomeric compounds with formula [Ln(μ-S-MPA)(S-MPA)2(phen)]n where Ln = Eu (S-Eu), Tb (S-Tb), Dy (S-Dy) and Sm (S-Sm). Single crystal X-Ray diffraction measurements were performed for compounds R/S-Eu, R/S-Tb, S-Dy and S-Sm. The luminescence and the circular dichroism measured in the solid state are reported. All compounds show sensitized luminescence, notably the Eu3+ and Tb3+ ones, whose emission color can be perceived by the naked eye. For the Eu3+ and Tb3+ derivatives the quantum yield and the circular polarized luminescence have been measured. For the magnetic allowed transition 5D0 → 7F1 of the Eu3+ compound, the anisotropy factor glum is ±0.013 (+for S-Eu). Also, magnetic properties of all compounds were studied with the Dy3+ analogue showing slow relaxation of the magnetization under a direct current magnetic field of 1000 Oe.

Six nickel-lanthanoid heterometallic complexes based on 2,5-dichlorobenzoate and phen: Syntheses, structures and magnetic properties

Six new zero-dimensional (0D) Ni(II)-Ln(III) heterometallic complexes, [Ln2Ni2(2,5-DCB)10(phen)2] [Ln = Nd (1), Sm (2), Eu (3), Gd (4), Tb (5) and Dy (6), 2,5-HDCB = 2,5‑dichlorobenzoic acid, phen = 1,10-phenanthroline], have been successfully synthesized by the reactions of Ln(NO3)3·6H2O, Ni(NO3)2·6H2O, 2,5‑dichlorobenzoic acid, NaOH and 1,10-phenanthroline under solvothermal conditions. All of these complexes have been characterized by single-crystal X-ray diffraction, elemental analysis, FT-IR spectroscopy, powder X-ray diffraction (PXRD) and thermogravimetric analysis (TGA) and differential thermoanalysis (DTA). Complexes 1–6 are isomorphous and have a linear tetranuclear cluster structure formed by the 2,5-DCB anions linking the Ni(II) and Ln(III) ions. The adjacent tetranuclear molecules are further extended into a two-dimensional (2D) supramolecular architecture by the π–π interactions. The magnetic properties of 1, 2 and 4–6 were investigated in detail. Complex 6 displays a field-induced single-molecule magnet (SMM) behavior with a Ueff value of 10 K.

Synthesis, Structure and Luminescence Characterizations of Pyramid-like Lanthanide-Titanium-Oxo Clusters EuTi9 and TbTi9

Two pyramid-like lanthanide − titanium − oxo clusters formulated as LnTi9(µ2-O)5(µ3-O)7(µ3-OH)2(OiPr)(acac)2(TCA)10(THF) (LnTi9, Ln = Eu / Tb, HTCA = 2-thiophenecarboxylic acid) were prepared through the reaction of Ln(acac)3, 2-thiophenecarboxylic acid (HTCA), Ti(OiPr)4 and THF. The 10-nuclearity-metal-core [LnTi9(µ2-O)5(µ3-O)7(µ3-OH)2]13+ is protected by four kinds of ligands. EuTi9 and TbTi9 exhibit characteristic emissions of Eu3+ / Tb3+ under ultraviolet excitation. The temperature-dependent luminescence results show EuTi9 shows a good linear relationship between the luminescence intensity and temperature range of 80–320 K, while TbTi9 has high temperature-sensitivity in different temperature ranges.

A new lanthanide–Schiff base ligand complex: structural characterization and biological effect on children nosocomial infection

In the present study, a new lanthanide–Schiff base ligand complex with the chemical formula of [Pr2(dbm)4L2(CH3OH)2]·2CH3OH (1, H2L = N'-[(1E)-[5-(hydroxymethyl)furan-2-yl]methylidene]pyrazine-2-carbohydrazide, Hdbm = 1,3-diphenylpropane-1,3-dione) has been successfully prepared via reaction of Ln(dbm)3·2H2O with the H2L ligand under the solvothermal reaction condition. The biological activity of the new compound on the children nosocomial infection was determined and the mechanism was explored at the same time. Firstly, the content of the inflammatory cytokines released into the plasma during nosocomial infection was measured with enzyme linked immunosorbent assay (ELISA) detection kit. In addition to this, the relative expression of the survival genes in the Staphylococcus aureus was determined with real time reverse transcription-polymerase chain reaction (RT-PCR).

Heteroleptic lanthanide(III) complexes: synthetic utility and versatility of the unsubstituted bis-scorpionate ligand framework

The unsubstituted bis-hydrotris(1-pyrazolyl)borate) (Tp) ligand framework has been used to synthesise a range of heteroleptic Ln(III) coordination complexes [Ln(Tp)2(X)]. The precursor complexes [Ln(Tp)2(OTf)] 1-Ln (Ln = Y, Eu, Gd, Yb; OTf = triflate) were synthesised by reaction of Ln(OTf)3 with two equivalents of K(Tp). The 8-coordinate β-diketonate complexes [Ln(Tp)2(hfac)] 2-Ln (Ln = Y, Eu, Yb; hfac = hexafluoroacetylacetonate) were synthesised from Ln(OTf)3 by reacting 1-Ln generated in situ with an equivalent of K(hfac). The 7-coordinate amide complexes [Ln(Tp)2(N″)] 3-Ln (Ln = Y, Yb; N″ = bis(trimethylsilyl)amide) were synthesised from 1-Ln by reaction with K(N″). Reactivity of 3-Ln towards protonolysis was demonstrated by the isolation of the hydroxide dimer [{Y(Tp)2(μ-OH)}2] 4-Y from adventitious reaction with water and the aryloxide complex [Ln(Tp)2(OAr)] 5-Ln (Ln = Y, Yb; OAr = 2,6-tBu2-4-Me-phenoxide) from reaction with H(OAr). Full characterisation data are presented for all complexes, including solid-state molecular structure determination by single-crystal X-ray diffraction.

Nitrile formation via dichlorocarbene insertion into the Si-N bond of Ln(III) bis(trimethylsilyl)amide complexes.

The reactions of Ln[N(SiMe3)2]3 (Ln = Eu, Sm, Yb) with chloroform yield the [Ln{N(SiMe3)2}2(μ-Cl)(NCSiMe3)]2 (Ln = Eu(1), Sm(2)) and Yb[N(SiMe3)2]3(NCSiMe3)2 (3) complexes, all of which contain two neutral Me3SiCN ligands. The unexpected formation of the Me3SiCN ligand represents a rare example of nitrile formation through the insertion of dichlorocarbene into the Si-N bond.

Magneto-thermal and magnetization relaxation dynamics of a family of di-nuclear lanthanide complexes

The reaction of Ln(NO3)3·nH2O (where Ln = Gd, Tb, Dy or Yb) in the presence of sodium acetate led us to isolate a family of structurally analogous dinuclear lanthanide complexes with the general molecular formula of [Ln2(CH3COO)4(NO3)2(H2O)4]. 2H2O (where Ln = Gd (1) or Tb (2) or Dy (3) or Yb (4)), which are characterized by single-crystal X-ray diffraction. The dc magnetic susceptibility measurements were performed on 1 reveal the presence of a weak ferromagnetic exchange between the Gd(III) center (J = +0.01 cm−1; −2JS1.S2 Hamiltonian). This weak exchange interaction in 1 is presumably overcome by the external magnetic field, and therefore, the X-band EPR spectral features of 1 were simulated by considering the single-ion spin Hamiltonian parameter (g = 1.98, D = 0.03 cm−1, and ∣E/D∣= 0.004). In contrast to 1, complexes 2–4 exhibit a weak antiferromagnetic exchange between the Ln(III) centers. The magnetization relaxation dynamics studies performed on the anisotropic complexes (2–4) show slow relaxation of magnetization in the presence of an optimum external magnetic field. The spin–lattice relaxation predominantly follows the Direct and Raman mechanism exclusively, and the Orbach process was found to be non-existent. By employing ab initio calculations, the electronic structure and the mechanism of magnetization relaxation dynamics of 2–4 have been investigated. The magnetocaloric effect parameter for 1 shows a change in magnetic entropy (−ΔSm) value of 39 J Kg−1 K−1 at 2.0 K (ΔH = 70 kOe), which is one of the largest −ΔSm value registered among the various discrete molecular coolants reported in the literature..

Syntheses and magnetic properties of a series of discrete Ni(II)-Ln(III) heterometallic complexes based on 2,3-dichlorobenzoate and 2,2′-bipyridine

Herein, a series of zero-dimensional (0D) heterometallic complexes, [Ln2Ni2(2,3-DCB)10(2,2′-bpy)2] [Ln = Nd (1), Sm (2), Eu (3), Gd (4), Tb (5), Dy (6), Er (7) and Yb (8)], were obtained by the reactions of Ln(NO3)3·nH2O, Ni(NO3)2·6H2O, 2,3-dichlorobenzoic acid (2,3-HDCB), NaOH and 2,2′-bipyridine (2,2′-bpy) under solvothermal conditions. The structures of complexes 1–8 were determined by single-crystal X-ray diffraction and further characterized by elemental analysis, FT-IR, PXRD and TGA. Complexes 1–8 are isostructural, and display discrete linear tetranuclear cluster structures constructed from ten 2,3-DCB anions linking two Ln(III) and two Ni(II) ions by four types of coordination modes. Such linear tetranuclear molecules can be extended into a two-dimensional (2D) supramolecular network through π–π interactions between 2,3-DCB and 2,2′-bpy. The magnetic properties of complexes 1–8 were also studied.

Dinuclear Lanthanide(III) Complexes from the Use of Methyl 2-Pyridyl Ketoxime: Synthetic, Structural, and Physical Studies.

The first use of methyl 2-pyridyl ketoxime (mepaoH) in homometallic lanthanide(III) [Ln(III)] chemistry is described. The 1:2 reactions of Ln(NO3)3·nH2O (Ln = Nd, Eu, Gd, Tb, Dy; n = 5, 6) and mepaoH in MeCN have provided access to complexes [Ln2(O2CMe)4(NO3)2(mepaoH)2] (Ln = Nd, 1; Ln = Eu, 2; Ln = Gd, 3; Ln = Tb, 4; Ln = Dy, 5); the acetato ligands derive from the LnIII—mediated hydrolysis of MeCN. The 1:1 and 1:2 reactions between Dy(O2CMe)3·4H2O and mepaoH in MeOH/MeCN led to the all-acetato complex [Dy2(O2CMe)6(mepaoH)2] (6). Treatment of 6 with one equivalent of HNO3 gave 5. The structures of 1, 5, and 6 were solved by single-crystal X-ray crystallography. Elemental analyses and IR spectroscopy provide strong evidence that 2–4 display similar structural characteristics with 1 and 5. The structures of 1–5 consist of dinuclear molecules in which the two LnIII centers are bridged by two bidentate bridging (η1:η1:μ2) and two chelating-bridging (η1:η2:μ2) acetate groups. The LnIII atoms are each chelated by a N,N’-bidentate mepaoH ligand and a near-symmetrical bidentate nitrato group. The molecular structure of 6 is similar to that of 5, the main difference being the presence of two chelating acetato groups in the former instead of the two chelating nitrato groups in the latter. The geometry of the 9-coordinate LnIII centers in 1, 5 and 6 can be best described as a muffin-type (MFF-9). The 3D lattices of the isomorphous 1 and 5 are built through H-bonding, π⋯π stacking and C-H⋯π interactions, while the 3D architecture of 6 is stabilized by H bonds. The IR spectra of the complexes are discussed in terms of the coordination modes of the organic and inorganic ligands involved. The Eu(III) complex 2 displays a red, metal-ion centered emission in the solid state; the TbIII atom in solid 4 emits light in the same region with the ligand. Magnetic susceptibility studies in the 2.0–300 K range reveal weak antiferromagnetic intramolecular GdIII…GdIII exchange interactions in 3; the J value is −0.09(1) cm−1 based on the spin Hamiltonian Ĥ = −J(ŜGd1·ŜGd2).

Regulating Spin Dynamics of Nitronyl Nitroxide Biradical Lanthanide Complexes through Introducing Different Transition Metals.

Four biradical-Ln complexes with different transition metal ions, namely [LnM(hfac)5 (NITPh-PyPzbis)] (MII =MnII and LnIII =Gd 1, Dy 2; MII =NiII and LnIII =Tb 3, Dy 4), were prepared by the reaction of Ln(hfac)3 ⋅ 2H2 O, Mn(hfac)2 ⋅ 2H2 O or Ni(hfac)2 ⋅ 2H2 O with NITPh-PyPzbis biradical (hfac=hexafluoroacetylacetonate, NITPh-PyPzbis=5-(3-(2-pyridinyl)-1H-pyrazol-1-yl)-1,3-bis(1'-oxyl-3'-oxido- 4',4',5',5'-tetramethyl-4,5-hydro-1H-imidazol-2-yl)benzene). In complexes 1-4, the NITPh-PyPzbis biradical chelates one LnIII ion by means of its aminoxyl moieties and the transition metal ion is introduced through the two N donors from the pyridyl pyrazolyl moiety. Magnetic investigations indicate that complex 4 displays visible maxima in frequency/temperature-dependent χ'' signals with two-step relaxation processes, but complex 2 exhibits no slow magnetization relaxation. The comparison of structure parameters of both Dy complexes indicates that the symmetries of coordination spheres of two Dy ions are D2d for 2 and C2v for 4, which thus probably results in different magnetic relaxation behaviors. This work provides new insight for improving properties of Ln-biradical based SMMs.

2D Near‐Infrared Luminescence Ln–Coordination‐Polymers as an Assistor for Biomedicine

AbstractConstructing Near‐Infrared (NIR) lanthanide coordination polymers (Ln‐CPs) is of great importance for biomedicial application, due to low toxicity and high‐resolution transparency of biological tissues. Yb3+ coordination polymer is researched widely because of its sharp emission at 980 nm could being identified and penetrate tissue easily. In our work, a rigid and highly symmetrical carboxylic acid H3L (2,2′‐((5‐carboxy‐1,3‐phenylene)bis(oxy))diacetic acid) was synthesised to build Ln‐CPs. The two‐dimensional (2D) lanthanide coordination polymers (Ln‐CPs)[Ln(L)(Dimethylacetamide)⋅H2O]n (Ln=Er, Yb) were obtained by the reaction of Ln(NO3)3 ⋅ 6H2O and H3L under 140 °C. Single Crystal X‐ray Diffraction (SCXRD) analysis indicates that all the Ln‐CPs present a 2D layer structure formed by lanthanide ions and linkers COO−. The structure of bulk samples were characterized by Powder X‐ray Diffraction (PXRD). The patterns indicate that Yb‐CP and Er‐CP are of excellent phase purity. We also explored the near‐infrared luminescence properties of these coordination polymers at solid‐state. Yb‐CP shows NIR emission at around 980 nm, which can be assigned to the 2F5/2→2F7/2 transition of the Yb3+ ion.

Some novel rare earth metal ions complexes: Synthesis, characterization, luminescence and biocidal efficiency

New lanthanide complexes (1–3) of the general formulae [Ln(L)(NO3)(H2O)] have been synthesized by reaction of Ln(NO3)3 {Ln = La (1), Sm (2) and Yb (3)} with 2,2'-(((1E,1′E)-thiophene-2,5-diylbis(methaneylylidene))bis(azaneylylidene))diphenol (H2L). Based on elemental analysis, spectroscopic studies (UV–Vis., FT-IR, ESI-MS, 1H/13C NMR), molar conductance and thermogravimetric analysis, the Schiff base ligand was suggested to coordinate Ln(III) ions through the azomethine nitrogens, deprotonated hydroxyl groups, and thiophene sulphur atom. The interaction of the synthetic compounds with CT-DNA has been studied by the electronic spectroscopy, fluorometric competition studies with ethidium bromide and DNA viscosity measurements. Furthermore, due to the ligand and its Ln(III) complexes exhibit good DNA binding affinity, it is considered worthwhile to investigate their antioxidant activity. The data have shown that, the complexes are more effective inhibitors towards reactive oxygen species (ROS), such as superoxide anion and hydroxyl radical. The activity of test compounds in ascending order (1) > (2) > (3) > H2L in terms of IC50 value. The anticancer activities of the complexes have also been studied towards human colon carcinoma cancer (HCT-116) and human breast cancer (MCF-7) cell lines.

Lanthanide bis(borohydride) complexes coordinated by tetradentate phenoxide ligand: Synthesis, structure, and catalytic activity in ring-opening polymerization of rac-lactide and ε-caprolactone

New lanthanide bis(borohydride) complexes coordinated by monoanionic tetradentate phenoxide ligand [(C5H4NCH2)2NCH2(3,5-tBu2C6H2O)]Ln(BH4)2 [Ln = Y (1), Nd (2), Sm (3)] were synthesized by the reactions of Ln(BH4)3(THF)3 with an equimolar amount of the lithium phenoxide [(C5H4NCH2)2NCH2(3,5-tBu2C6H2O)Li] in THF at 60 °C. The complexes were isolated after recrystallization from toluene in 75, 64, and 69% yields, respectively. X-ray analysis revealed that in 1 the phenoxide ligand is tetradentate, while two borohydride groups are coordinated to the Y3+ ion in a κ3-fashion. Compounds 1–3 initiate ring-opening polymerization (ROP) of ɛ-caprolactone (ɛ-CL) and racemic lactide (rac-LA) in toluene at 25 °C. The obtained polylactides are characterized by atactic structures Pr = 0.54–0.58, and rather narrow polydispersities (Mw/Mn = 1.1–1.5). For ɛ-caprolactone polymerization, the resulting polymers have moderate polydispersities (Mw/Mn = 1.4–2.4) and molecular weights (6.2–54.1·103).

Samarium, Europium, and Gadolinium Complexes with 4-(2,1,3-Benzothiadiazol-4-ylamino)pent-3-en-2-onate

New lanthanide complexes with 4-(2,1,3-benzothiadiazol-4-ylamino)pent-3-en-2-onate (L–) [Ln(L)3] are synthesized using two methods: by the reaction of Ln(N(SiMe3)2)3 with the protonated form of the ligand LH (Ln = Sm, Gd) and by the reaction of LnCl3 (Ln = Eu) with LH in the presence of KN(SiMe3)2 as a base. According to the X-ray diffraction data, the synthesized complexes [Ln(L)3] · 0.5Solv (Solv = THF, C7H8) are isotypical (CIF files CCDC nos. 1826520, 1826521, and 1826522 for Sm, Eu, and Gd, respectively). A specific feature of the structures is the disordering of the metal atom and one of the ligands over two positions when the fragments of the ligands are arranged via the head-to-tail type occupying the same volume of the space. This probably leads to failure in the crystal lattice. The photoluminescence spectra of [Sm(L)3] · 0.5THF are recorded. A relationship between the coordination mode of the ligand and the position of the long-wavelength band of the electron transitions in the complexes with the L– ligand is revealed.

A series of dinuclear lanthanide complexes derived from a hydroxyl-rich ligand: {Dy2} exhibiting single-molecule magnet behaviour

Seven dinuclear lanthanide complexes of formulae Ln2L2 (Ln = Sm (1), Eu (2), Gd (3), Tb (4), Dy (5)), Ho2L2·MeCN (6) and Er2L2·MeCN (7) (H3L = 2-{[bis(2-hydroxy-3-ethoxybenzyl)(aminoethyl)amino]methyl}phenol) have been synthesized by the reactions of Ln(NO3)3∙6H2O with the hydroxyl-rich ligand H3L in MeCN/NEt3 solution. The structures of the isostructural complexes 1–7 were determined by single-crystal X-ray crystallography. X-ray crystallography analyses reveal that each compound is neutral and consists of two metal centers and two triply-deprotonated ligands. The two Ln(III) atoms in 1–7 are doubly bridged by two phenolato oxygen atoms of two L3− ligands. Each of the two lanthanide ions is seven-coordinated and possesses capped trigonal prism geometry. Dc magnetic susceptibility studies in the 2–300 K range reveal probably weak antiferromagnetic interaction for 3–7. Complex 5 exhibits frequency dependence of the ac-susceptibility typical of single-molecule magnets.