Samarium Complexes Research Articles

A novel samarium complex with interesting photoluminescence and semiconductive properties

[Sm(H2O)4(NO3)3](4,4'-Hbipy)2(NO3)2 (1) (bipy = bipyridine) has been synthesized via hydrothermal reaction and characterized by X-ray diffraction. The title complex features an isolated structure, based on discrete 4,4'-Hbipy moieties, isolated nitrates and [Sm(H2O)4(NO3)3] species. The samarium ion is in a distorted bicapped square antiprism environment, coordinated by three bidentate nitrates and four coordination water molecules. The 4,4'-Hbipy moieties, isolated nitrates and [Sm(H2O)4(NO3)3] species are held together via hydrogen bonds and p…p interactions to form a 3-D supramolecular framework. Luminescent investigation reveals a strong emission in blue region. Optical absorption spectrum of 1 reveals the presence of an optical gap of 3.60 eV. KEY WORDS: Bipyridine, Crystal structure, Fluorescence, Hydrothermal reaction, Samarium Bull. Chem. Soc. Ethiop. 2017, 31(3), 435-444. DOI: http://dx.doi.org/10.4314/bcse.v31i3.7

Preparation, and Luminescence Properties of SiO2@Sm(MABA-Si)phen Core-Shell Structure Nanometer Composite

A novel ternary samarium complex was prepared using HOOCC6H4N(CONH(CH2)3Si- (OCH2CH3)3)2 (MABA-Si) as first ligand, and phen as second ligand. The corresponding SiO2@Sm(MABA-Si)phen core-shell structure nanometer composite was synthesized as well, and the silica spheres was the core, and the ternary samarium complex was the shell layer. The ternary samarium complex has been characterized by element analysis, molar conductivity and IR spectra. The results show that the chemical formula of the complex is Sm(MABA-Si)(phen)2(ClO4)3·2H2O. The fluorescent spectra illustrat that the luminescence properties of the samarium complex are superior. The core-shell structure of SiO2@Sm(MABA-Si)phen nanometer composite is characterized by SEM, TEM and IR spectra. The SiO2@Sm(MABA-Si)phen core-shell structure composites exhibit stronger emission intensity than the ternary samarium complex. The fluorescence lifetime of the complex and core-shell structure composite is measured as well.

Regulating structural dimensionality and emission colors by organic conjugation between SmIII at a fixed distance.

The conjugation of bridging bis(diphenylphosphine oxide) alkane or arene ligands was found to control the structural dimensionality and the emission color of complexes from reactions with SmIII(hfac)3(H2O)2 (hfac- = hexafluoroacetylacetonato) while retaining the SmSm distances. Bis(diphenylphosphine oxide)-1,4-butane (L1) affords a one-dimensional (1D) ribbon {Sm(hfac)3(L1)}∞ (1) that emits red color, while bis(diphenyl-phosphinoyl)-1,4-benzene (L2) results in a two-dimensional (2D) network {Sm(hfac)2(CF3COO)(L2)3}∞ (2) and near-white emission, but bis(diphenyl-phosphinoyl)-9,10-anthracene (L3) forms a zero-dimensional (0D) cyclic structure {Sm(hfac)3(L3)}2 (3) with strong ππ interactions that emit green color. Noticeably, the conjugation change is accompanied by a configurational change of coordination from trans for 1 and 2 to cis for 3. The color change is associated with the superposition of ligand and Sm based electronic band energies and their intensities. Such white light emission by a single compound having contributions from different building components is quite rare.

Synthesis and Luminescence Properties of the Binary/Ternary Complex of Samarium Ion with Phenacylmethyl P-Tolyl Sulfoxide and Benzoic Acid

A new ligand phenacylmethyl p-tolyl sulfoxide (denoted as L1) has been synthesized by an asymmetric synthesis method. Its novel binary complex Sm(L1)7·(ClO4)3·6H2O, and ternary complex Sm(L1)6·(L2)·(ClO4)2·6H2O (benzoic acid denoted as L2) have been synthesized. The structure and composition of the samarium complexes characterized by elemental analysis, molar conductivity, IR, UV, and 1HNMR. Additionally, fluorescence spectra measurements shows that the complexes display stronger fluorescence intensity in solid state, indicating the ligands could efficiently transfer the energy to Sm3+ ions in the complexes. The ternary complex has stronger fluorescence intensity than the binary complex.

Synthesis and Structure of Unprecedented Samarium Complex with Bulky Bis‐iminopyrrolyl Ligand via Intramolecular C=N Bond Activation

An unprecedentate samarium complex of the molecular composition [{κ3‐{(Ph2CH)N=CH}2C4H2N)}{κ3‐{(Ph2CHN=CH)(Ph2CHNCH)C4H2N}Sm}2] (2), which was isolated by the reaction of a potassium salt of 2,5‐bis{N‐(diphenylmethyl)‐iminomethyl}pyrrolyl ligand [K(THF)2{(Ph2CH)N=CH}2C4H2N)] (1) with anhydrous samarium diiodide in THF at 60 °C through the in situ reduction of imine bond is presented. The homoleptic samarium complex [[κ3‐{(Ph2CH)–N=CH}2C4H2N)]3Sm] (3) can also be obtained from the reaction of compound 1 with anhydrous samarium triiodide (SmI3) in THF at 60 °C. The molecular structures of complexes 2 and 3 were established by single‐crystal X‐ray diffraction analysis. The molecular structure of complex 2 reveals the formation of a C–C bond in the 2,5‐bis{N‐(diphenylmethyl)iminomethyl}pyrrole ligand moiety (Ph2Py–). However, complex 3 is a homoleptic samarium complex of three bis‐iminopyrrolyl ligands. In complex 2, the samarium ion adopts an octahedral arrangement, whereas in complex 3, a distorted three face‐centered trigonal prismatic mode of nine coordination is observed around the metal ion.

Reductive Disproportionation of CO2 with Bulky Divalent Samarium Complexes

The base-free divalent samarium complex Cptt2Sm (1; Cptt = 1,3-(tBu)2(C5H3)) has been synthesized in diethyl ether by salt metathesis of SmI2. Crystals of 1 suitable for X-ray study have been obtained by sublimation at 116 °C under reduced pressure. The dissolution of 1 in thf and pyridine solution leads to the solvent adducts Cptt2Sm(thf)2 (3) and Cptt2Sm(py) (4), respectively, while drying 3 under reduced pressure yields CpttSm(thf) (5). The reaction of CO2 with the base-free divalent samarium complexes Cptt2Sm (1) and Cpttt2Sm (2; Cpttt =1,2,4-(tBu)3(C5H2)) leads to the clean formation of bridged carbonate samarium dimers [Cpttt2Sm]2(μ-CO3) (7) and [Cptt2Sm]2(μ-CO3) (8). This is indicative of the reductive disproportionation of CO2 in both cases with release of CO. This contrasts with the formation of the oxalate-bridged samarium dimer reported from the reaction of CO2 with the Cp*2Sm(thf)2 complex. Otherwise, the reaction with CO does not proceed with the bulky complexes, while traces of O2 have led t...

Actividad catalítica de complejos p-R-cinamato de Ce(III), Nd(III) y Sm(III) en la oxidación de β-pineno y canfeno

Se realizó la síntesis de nueve complejos lantánidos de cerio, neodimio y samario con ligandos trans-cinamato (L1), trans-p-clorocinamato (L2) y trans-p-metoxicinamato (L3). La caracterización se realizó mediante espectroscopia FT-IR, análisis térmicos (TGA y DSC) y análisis elemental. Los compuestos obtenidos se utilizaron como catalizadores para la oxidación de canfeno y β-pineno, usando peróxido de hidrógeno (30 %) y ácido peracético (12 %) como agentes oxidantes. En la oxidación de canfeno, el complejo [Nd(L2)3] presentó la conversión más alta (97.99 %) con una selectividad del 84.05 % hacia el ácido 3-canfenilocarboxílico, mientras que en la oxidación de β-pineno, el complejo [Ce(L3)3 . 2H2O] presentó la conversión más alta (82.62 %) con una selectividad hacia la nopinona del 70.52 %.

Reductive Trapping of [(OC)5 W-W(CO)5 ]2- in a Mixed-Valent SmII/III Calix[4]pyrrolide Sandwich.

Reduction of tungsten hexacarbonyl by the divalent samarium(II) complex [Sm2 (N4 Et8 )(thf)4 ] ((N4 Et8 )4- =meso-octaethylcalix[4]pyrrolide) in toluene at ambient temperature gave the remarkable heteronuclear mixed-valent samarium(II/III)/tungsten complex [{(thf)2 SmII (N4 Et8 )SmIII (thf)}2 {(μ-OC)2 W2 (CO)8 }], which features the trapping of a rare [W2 (CO)10 ]2- anion with an unsupported W-W bond.

Reductive Trapping of [(OC)5W–W(CO)5]2− in a Mixed‐Valent SmII/III Calix[4]pyrrolide Sandwich

AbstractReduction of tungsten hexacarbonyl by the divalent samarium(II) complex [Sm2(N4Et8)(thf)4] ((N4Et8)4−=meso‐octaethylcalix[4]pyrrolide) in toluene at ambient temperature gave the remarkable heteronuclear mixed‐valent samarium(II/III)/tungsten complex [{(thf)2SmII(N4Et8)SmIII(thf)}2{(μ‐OC)2W2(CO)8}], which features the trapping of a rare [W2(CO)10]2− anion with an unsupported W−W bond.

Use of samarium(III)–amino acid complexes as initiators of ring-opening polymerization of cyclic esters

Poly(e-caprolactone) (PCL) and poly(l-lactide) (PLA) were prepared by ring-opening polymerization (ROP) using samarium(III) acetate (SmAc3) and amino acid complexes of samarium(III) as initiators. The catalytic behavior of samarium(III) acetate and their respective amino acid complexes, Sm(2,2′-bipyridine)(Ln)3 (L1 = l-aspartic acid; L2 = l-glutamic acid and L3 = glycine), was studied. It could be observed that the amino acid structure and chemical bond type have great influence on the catalytic activity. Polymerization reaction temperature was 125 °C and the effect of time reaction on the conversion of monomers to polymers and the molecular weight were studied. The results indicate that the initiators induce the polymerization of e-caprolactone (e-CL) and l-lactide (l-LA). Polymers were characterized by size exclusion chromatography (SEC) and nuclear magnetic resonance (1H-NMR) and size exclusion chromatography (SEC). Polyesters with average-number molar mass of 1.50 × 103 − 104 Da were obtained. Based on the 1H-NMR end group analysis of low molecular weight of polymers, a coordination–insertion mechanism is proposed for the polymerization of lactones. Kinetics study indicated a polymerization rate of first order with respect to monomer concentration. Differences in the rates of polymerization in the four initiators appeared to be governed by the different degrees of steric hindrance in the initiator structure and monomer.

Ligand‐Field Asymmetry‐Controlled Luminescent Europium (III) and Samarium(III) Tris(β‐diketonate) Complexes of Diphenyl‐(2‐pyridyl‐N‐oxide)‐ Phosphine Oxide

AbstractEight new complexes of the type Ln(OO)3.2 L1, Ln(OO)3.L2 (where Ln=Eu, Sm; OO=thenoyl trifluroacetonate(TTA) and dibenzoylmethanate(DBM); L1=diphenyl, (2‐pyridyl) phosphine oxide (PON) and diphenyl‐(2‐pyridyl‐N‐oxide)phosphine oxide (PONO)) were synthesized for the first time. Complexes were characterized by FTIR, CHN analyses and Single crystal X‐ray diffraction techniques. Structures of samarium complexes show that the L1 behaves as a monodentate ligand and bonds through P=O group to metal centre, whereas L2 behaves as a bidentate ligand and bonds through P=O as well as N−O groups to metal centre. Photophysical properties of all the complexes were measured in solid as well as solution states. Due to increase in ligand field asymmetry around the metal centre (by changing ligand from L1 to L2), the asymmetry ratio REu in Europium(III) tris( diketonate)‐L2 complexes were increased. This leads to increase in intrinsic quantum yield complexes with ligand L2 as compared to that of complexes of ligand L1.

Enantiomeric NMR signal separation behavior and mechanism of samarium(III) and neodymium(III) complexes with (S,S)-ethylenediamine-N,N'-disuccinate.

Enantiomeric 1 H and 13 C NMR signal separation behaviors of various α-amino acids and DL-tartarate were investigated by using the samarium(III) and neodymium(III) complexes with (S,S)-ethylenediamine-N,N'-disuccinate as chiral shift reagents. A relatively smaller concentration ratio of the lanthanide(III) complex to substrates was suitable for the neodymium(III) complex compared with the samarium(III) one, striking a balance between relatively greater signal separation and broadening. To clarify the difference in the signal separation behavior, the chemical shifts of β-protons for fully bound D- and L-alanine (δb (D) and δb (L)) and their adduct formation constants (Ks) were obtained for both metal complexes. Preference for D-alanine was similarly observed for both complexes, while it was revealed that the difference between the δb (D) and δb (L) values is the significant factor to determine the enantiomeric signal separation. The neodymium(III) and samarium(III) complexes can be used complementarily for higher and smaller concentration ranges of substrates, respectively, because the neodymium(III) complex gives the larger difference between the δb (D) and δb (L) values with greater signal broadening compared to the samarium(III) complex.

Recyclable Single-Component Rare-Earth Metal Catalysts for Cycloaddition of CO2 and Epoxides at Atmospheric Pressure.

Ionic rare-earth metal complexes 1-4 bearing an imidazolium cation were synthesized, which, as single-component catalysts, showed good activity in catalyzing cyclic carbonate synthesis from epoxides and CO2. In the presence of 0.2 mol % catalyst, monosubstituted epoxides bearing different functional groups were converted into cyclic carbonates in 60-97% yields under atmospheric pressure. In addition, bulky/internal epoxides with low reactivity yielded cyclic carbonates in 40-95% yields. More importantly, the readily available samarium complex 2 was reused for six successive cycles without any significant loss in its catalytic activity. This is the first recyclable rare-earth metal-based catalyst in cyclic carbonate synthesis.

Photo and electroluminescence of a platinum porphyrin doping of complexes with two metal cores

In this paper, four new complexes with two metal cores [2Sm, 2Sn, 2Zn and 2Pb] were prepared and utilized as host material in in the electroluminescence (EL) devices. Devices with two metal cores and with the structure of ITO/PEDOT: PSS (60 nm)/PVK (55 nm)/[2Sm, 2Sn, 2Zn and 2Pb]: %8 [2,5PtTPP] (45 nm)/Al (200 nm) were fabricated, A blue–green photoluminescence (PL) emission with a blue shift compared to the 2,5PtTPP was observed. 2,5PtTPP doped in 2Sm and 2Sn showed more pure red color compared to 2Zn and 2Pb based devices. We believe that energy transfer occurring at 2,5PtTPP/[2Sm, 2Sn] molecules is responsible for the red color in the EL of the device. The electronic effect of two metal cores of complexes influenced the maximum current density, brightness, and luminous efficiency of the devices. Finally, we have demonstrated the samarium complex of 8-hydroxyquinoline is a promising host material for red OLEDs with high efficiency and has a simple device structure.

Synthesis and photoluminescence properties of pink luminescent heteroleptic Sm(III) complexes; the role of DMSO in transforming the inner coordination sphere and on photophysical properties. Sparkle/RM1 calculation

Three new heteroleptic pink luminescent samarium complexes of the type [Sm(tfaa)3L] and [Sm(tfaa)3]2L′ were synthesized [where tfaa=1,1,1-trifluoro-2,4-pentanedione and L=2,2′-bipyridine (bpy) or 1,10-phenanthroline (phen) and L′=2,2′-bipyridimidine (bpm)] and characterized by elemental analysis, FT-IR, thermogravimetry and 1H NMR spectroscopy. The coordination geometries of the Sm(III) complexes were calculated by the Sparkle/RM1 model. The complexes have excellent thermal properties and melt at 197 [Sm(tfaa)3bpy], 198 [Sm(tfaa)3phen] and 186°C [Sm(tfaa)3]2bpm. The photophysical properties of the complexes were analyzed in chloroform (non-coordinating) and DMSO (coordinating). Pink luminescence is observed for all the complexes. Substitution of the water molecule from the coordination sphere of [Sm(tfaa)3H2O] by ancillary ligands leads to a 4.71 (phen and bpy) and 3.26 (bpm) fold increase in the luminescence lifetime. This enhancement originates mainly due to (i) better sensitization of the Sm(III) ion by the ancillary ligands and (ii) elimination of non-radiative deactivation pathways through the harmonics of the O–H vibration. The most interesting feature of the study is the similar spectral band shapes, intensities, lifetimes and quantum yields for the complexes in DMSO. The similar spectral shapes and lifetimes of the complexes in DMSO are due to the replacement of the ancillary ligands (i.e. bpy, phen and bpm) and water, and the transformation of the complexes into [Sm(tfaa)3(DMSO)2] species in solution.

Lanthanide(III) complexes with tridentate Schiff base ligand, antioxidant activity and X-ray crystal structures of the Nd(III) and Sm(III) complexes

The tridentate N4-type Schiff base was synthesized from the condensation reaction of 2-hydrazinopyridine and pyridine-2-carbaldehyde. Neodymium and Samarium complexes were isolated when the corresponding nitrate salt was added to the solution of the ligand. The isolated compounds were characterized by elemental analyses, IR study, room temperature magnetic measurements and single X-ray crystal diffraction of the two crystals. Both complexes crystallize in the monoclinic system with space group P21/c. The cell parameters of the Nd complex are a = 11.0927(8) A, b = 17.9926 (13) A, c=11.9395(9) A and β = 115.274(5) ° while the Sm complex shows parameters cell of a = 11.0477(8) A, b = 17.9254(13) A, c = 11.9149(8) A and β = 115.489(5) °. The X-ray study reveals isotopic Nd/Sm binuclear structures were each metal ion is nine-coordinated in the same fashion. Both metal centers have distorted tricapped trigonal prism geometry, with the Schiff base acting as tridentate ligand. The DPPH· radical scavenging effects of the Schiff base ligand and its Ln(III) complexes were screened. The Ln(III) complexes were significantly more efficient in quenching DPPH· than the free Schiff base ligand.

Half-Sandwich Alkyl, Amido, and Iodo Samarium(II) Complexes: Non-Conventional Sterically Governed Oxidation of (tBu4 Carb)2 Sm.

The half-sandwich tetra-tert-butylcarbazol-9-yl iodo complex [(tBu4 Carb)Sm(μ-I)(THF)2 ]2 (1) was synthesized by the salt metathesis reaction of tBu4 CarbK and SmI2 (THF)2 in THF. Complex 1 along with metallic Cu was also isolated from the oxidation reaction of (tBu4 Carb)2 Sm by CuI. The formation of stable radical tBu4 Carb. was detected in this non-conventional process, indicating preferential oxidation of anion tBu4 Carb- vs. SmII . The treatment of 1 with two equivalents of dibenzo-18-crown-6 resulted in heterolytic dissociation of a η5 -bond Sm-tBu4 Carb and afforded an ionic compound [tBu4 carb- ][SmI(crown)(THF)2 ]+ (4). Alkylation of 1 with o-NMe2 C6 H4 CH2 K (1:2 molar ratio) in THF allowed for the synthesis of half-sandwich SmII alkyl complex (tBu4 Carb)SmCH2 (o-NMe2 C6 H4 CH2 )(THF)2 (5) in 55 % yield. The amido complex (tBu4 Carb)SmN(SiMe3 )2 (DME) (6) was obtained by the reaction of 1 with two molar equivalents of NaN(SiMe3 )2 in THF in 89 % yield.

Coordination compound of samarium(III) with acylhydrazone of N-(2-hydroxyphenyl)iminodiacetic acid and 5-hydroxy-3-methyl-1-phenyl-4-formylpyrazole

The structure of a samarium(III) complex with acylhydrazone of N-(2-hydroxyphenyl)iminodiacetic acid and 5-hydroxy-3-methyl-1-phenyl-4-formylpyrazole (Н5L) of the composition [Sm2(Н3L)3]·С2Н5ОН··10Н2О has been determined by single crystal X-ray diffraction. It has been found that in the dinuclear complex the coordination polyhedra have the geometry of a slightly distorted tri-capped trigonal prism and are linked with three iminodimethylene bridges arranged in a triple helix.

Poly complexes based unsaturated β-diketones and rare earth elements for optoelectronics

ABSTRACTThe complexes of samarium(III) with 2-methyl-5-phenylpenten-1-3,5-dione (mphpd) Sm(mphpd)3·2H2O and 2,6-dymethyl-heptene-1-3,5-dione (hdmhpd), Sm(hdmhpd)m were synthesized. The polycomplexes on their basis [Sm(mphpd)3]n, [Sm(hdmhpd)m]n and copolymers with styrene Sm(mphpd)3-co-styrene in ratio 5:95 were obtained by free-radical polymerization and the kinetics of polymerization was studied by dilatometric method at the first time. The method of dynamic light scattering and the results of electronic microscopy showed that the obtained polymer systems are nanoscale. The luminescent spectra of obtained metal complexes in solid state are investigated and analyzed. The electroluminescent spectra of organic planar heterostructure ITO/PEDOT:PSS/{[Sm(mphpd)3]n[Styrene]m}/Al are examined.

Side-on coordination mode of a pyrazolyl group in the structure of a divalent [Sm{B(3-Mepz)4}2] complex (3-Mepz is 3-methylpyrazol-1-yl).

The discovery of polypyrazolylborate ligands allowed the development of various chemical fields and these ligands are an alternative to cyclopentadienyl, because both ligands have the same charge and donate the same number of electrons, as well as adopting the same facial geometry. Easy control of the bulkiness of polypyrazolylborate ligands is possible by modification of the substituents in the 3- and 5-positions of the pyrazolyl rings. The title complex, bis[tetrakis(3-methyl-1H-pyrazol-1-yl)borato]samarium(II), [Sm(C16H20BN8)2], was synthesized from the reaction of SmI2 with potassium tetrakis(3-methyl-1H-pyrazol-1-yl)borate, denoted K[B(3-Mepz)4], in tetrahydrofuran. The X-ray structure analysis revealed an unusual side-on coordination mode of a 3-methylpyrazolyl group through an N=N group in the B(3-Mepz)4 ligand. The distortion is defined by the B-N-N-Sm torsion angle [85.5 (4)°]. This is in contrast to the structure of the similar divalent samarium complex [Sm(TpMe2 is tris(3,5-dimethylpyrazol-1-yl)borate], which displays normal κ3-bonding modes of the TpMe2 ligands.