Polymerization of 4—Vinylpyridine by Lanthanide Coordination Catalyst

Polyvinylpyridines are an important class of polymers that exhibit interesting properties due to the presence of the nitrogen atom in the pyridine ring. The weakly basic nitrogen atom makes possible a variety of reactions on vinylpyridine polymers, e.g. reaction with acids, quaternization and complexation of metals. In addition, these polymers are mainly attractive in applications as polyelectrolytes, polymeric reagents etc. Few papers about polymerization of 4-vinylpyridine (4-Vpy) with co…     

Ring-opening Polymerization of ε-Caprolactone Using Lanthanide Tris（4-tert-butylphenolate）s as a Single-component Initiator

The ring-opening polymerization of ε-caprolactone (CL) initiated by novel singlelanthanide tris(4-tert-butylphenolate)s [Ln(OTBP)3] is reported. Single-component La(OTBP)3can effectively prepare polycaprolactone (PCL) with over 90% yield and viscosity averagemolecular weight about 60 × 103 under quite mild conditions: molar ratio of CL to initiator is 1000,60 ℃, 2 h in toluene. Mechanism study indicates that the monomer inserts into the growing chainvia the break of acyl-oxygen bond of CL.     

Syntheses and Properties of Lanthanide Hydroxy-meso-tetra（p-chlorophenyl） porphyrin Complexes

The syntheses and characterization of porphyrins and metalloporphyrins have been studied extensively. Hemoglobin, myoglobin or cytochrome P450, has been applied as a model compound. Wong C. P. et al. synthesized the first lanthanide porphyrin, acetylacetonate tetraphenylporphyrin europium, in 1974. Since then the study of porphyrin complexes, as a new field, has devel-     

Synthesis of 4-Aminosalicylglycine

To search for a better prodrug of 4-aminosalicylic acid that is expected to deliver stably parent drug to colon against the inflammatory bowel disease, a novel 4-aminosalicylic acid derivative was designed and synthesized from 4-aminosalicylic acid. 4-Aminosalicylglycine was prepared from 4-aminosalicylic acid by protecting amino and hydroxyl groups with benzyloxycarbonyl and acetyl, respectively, then the carboxylic acid was converted to acyl chloride which was treated with glycine. After removing the protection groups, 4-aminosalicylglycine wasobtained. All the compounds were characterized by FT-IR, ^1H-NMR, ^13C-NMR spectra. In vivo experiment on rats suggested that the curative effect of 4-aminosalicylglycine was more effective than that of 4-aminosalicylic acid.     

Lanthanide Complexes for Oligomerization of Phenyl Isocyanate

IntroductionThestudyonthereactivitiesoflanthanidecomplexesto wardisocyanateshasattractedmuchattention .Ithasbeenre portedthatlanthanidealkoxides,1anddivalentdiaza pentadi enyllanthanidecomplexes2 canbeusedasthesinglecompo nentinitiatorsforisocyanatespolymerization .Recentlyourre searchgrouphasalsofoundthatlanthanoceneamide ,3diva lentaryloxideofsamarium4 ,5anddivalentsamarocene6 areallactivefortheoligomerizationofphenylisocyanate,andtheactivespeciesforthesethreesystemswereallsuccessfullyisolat…     

Synthesis of Lanthanide Coordination Polymers with Benzophenone-4,4-dicarboxylate: Effect of Lanthanide Contraction on Structures

Introduction Recently, the coordination polymers based on dicar-boxylic acid have been studied extensively for their importance as promising materials.1-7 So the rational design and synthesis of novel coordination polymers with useful functions attract considerable attention. As well known, the design of extended structure with po-tential applications can be realized by starting with connecting ligands capable of binding metal centers strongly and predictably to afford the structures with expe…     

Cleavage of Nucleotides by Lanthanide Metal Complexes

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Ring-opening Polymerization of 6-Caprolactone by Lanthanide Tris（ 2,6- dimethylphenolate ） s

Lanthanide tris ( 2,6-dimethylphenolate ) s [ Ln ( ODMP)3 ] were used as iniliators for ring-opening polymerization of e-caprolac-tone (CL) for the first time. The influence of different rare earth elements and solvents was investigated. ^1H NMR spectral data of polycaprolactone (PCL) obtained showed that the poly-merization mechanism is in agreement with the coordination-in-sertion mechanism and the selective cleavage of the acyl-oxygen bond of CL.     

Study and Application of Polarographic Catalytic Wave of Chlordiazepoxide in the Presence of Persulfate

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Syntheses and Photo-electronic Properties of Lanthanide Acetylacetonate Benzoporphyrins

Metalloporphyrin compounds have been extensively studied in many functional chemistry fields, such as photo-physics and liquid crystal quality studies^[1-5]. But the studies of lanthanide acetylacetonate benzoporphyrin complexes with meso-tetra-alkyl substituents in the ligand [Ln(TATBP)acac] have not been reported yet.     

Supramolecular Assembly of Double‐Stranded Chains,Helical Chains and Catenane‐like Layers with Flexible Ligands

Four new transition metal coordination polymers, [Co(bpndc)(phen)(H₂O)]_n ( 1 ), [Co₃(bpndc)₃(2,2′‐bpy)₂]_n·0.5n(i‐C₃H₇OH) ( 2 ), and [M(bpndc)(2,2′‐bpy)₂]_n (M = Zn, 3 ; Cu, 4 ; H₂bpndc = benzophenone ‐4,4′‐dicarboxylic acid; phen = 1,10‐phenanthroline; 2,2′‐bpy = 2,2′‐bipyridine) have been synthesized by the hydrothermal reactions and characterized by single crystal X‐ray diffraction, elemental analysis, and IR spectrum. Because of the introduction of different terminal auxiliary ligands, bpndc ligands in complexes 1 and 2 adopt different coordination modes. In complex 1 , bpndc ligands act as tridentate ligand and bridge Co^II ions into 1D double‐stranded chains; while complex 2 possesses 2D (4,4) grids, where bpndc ligands adopt tetradente and pentadentate modes. Two such grids interpenetrate to form a novel catenane‐like layer. Complexes 3 and 4 are isostructural. Bpndc ligands adopt tetradentate mode and bridge metal ions forming 1D helical chains.     

Poly[aqua(μ3‐benzene‐1,2‐dicarboxylato)bis(μ3‐hydroxido)bis(μ2‐isonicotinato)dierbium(III) monohydrate] and the thulium analogue

The two isomorphous lanthanide coordination polymers, {[Ln₂(C₆H₄NO₂)₂(C₈H₄O₄)(OH)₂(H₂O)]·H₂O}_n (Ln = Er and Tm), contain two crystallographically independent Ln ions which are both eight‐coordinated by O atoms, but with quite different coordination environments. In both crystal structures, adjacent Ln atoms are bridged by μ₃‐OH groups and carboxylate groups of isonicotinate and benzene‐1,2‐dicarboxylate ligands, forming infinite chains in which the Er...Er and Tm...Tm distances are in the ranges 3.622 (3)–3.894 (4) and 3.599 (7)–3.873 (1) Å, respectively. Adjacent chains are further connected through hydrogen bonds and π–π interactions into a three‐dimensional supramolecular framework.     

Stable 8-hydroxyquinolinate-based podates as efficient sensitizers of lanthanide near-infrared luminescence

New polydentate ligands (e.g., Tsox and TsoxMe) have been synthesized to take advantage of the chelating effect of bidentate 8-hydroxyquinolinate subunits connected to a N,N,N',N'-tetraaminopropyl-1,2-ethylenediamine framework and with the aim of sensitizing the NIR luminescence of Nd(III) and Yb(III) ions. Ten pK(a)'s have been determined and the interaction between the ligands and Ln(III) ions in dilute aqueous solution has been probed both by potentiometric and spectrophotometric titrations. These studies have been mostly performed with the Eu(III) ion, which is in the middle of the lanthanide series, and extended to other ions (La(III), Er(III), Lu(IIII)). Stable complexes with Ln(III) ions are formed (pLn in the range of 14-16), the four chromophoric units being coordinated to the metal center, exploiting the entropic effect generated by the anchor. The monometallic complexes [Ln(H(2)L)](3)(-) exist as the major species at physiological pH regardless of the lanthanide used. Lifetime determinations of the Nd((4)F(3/2)) and Yb((2)F(5/2)) excited levels in both H(2)O and D(2)O at buffered pH point to the absence of water molecules bound in the inner coordination sphere of the Ln(III). Photophysical properties of the free ligands and of their lanthanide complexes have been investigated in buffered aqueous solutions both at room temperature and 77 K. The low-energy triplet state makes energy transfers from the ligand to the metal ions possible; this leads to a sizable sensitization of the Nd(III)- or Yb(III)-centered luminescence ( = 0.02% and = 0.18%) for Tsox chelates. Methylation of the amide functions removes the quenching mechanism induced by the proximate N-H vibrations and increases both the lifetimes and quantum yields of the TsoxMe chelates ( = 0.04% and = 0.37%). In fact, TsoxMe yields one of the most luminescent Yb(III) compounds known in water, and this ligand appears to be suitable for the development of NIR probes for bioanalyses.     

Lanthanide(III) Complexes of 4,10‐Bis(phosphonomethyl)‐1,4,7,10‐tetraazacyclododecane‐1,7‐diacetic acid (trans‐H6do2a2p) in Solution and in the Solid State: Structural Studies Along the Series

Complexes of 4,10‐bis(phosphonomethyl)‐1,4,7,10‐tetraazacyclododecane‐1,7‐diacetic acid (trans‐H₆do2a2p, H₆ L ) with transition metal and lanthanide(III) ions were investigated. The stability constant values of the divalent and trivalent metal‐ion complexes are between the corresponding values of H₄dota and H₈dotp complexes, as a consequence of the ligand basicity. The solid‐state structures of the ligand and of nine lanthanide(III) complexes were determined by X‐ray diffraction. All the complexes are present as twisted‐square‐antiprismatic isomers and their structures can be divided into two series. The first one involves nona‐coordinated complexes of the large lanthanide(III) ions (Ce, Nd, Sm) with a coordinated water molecule. In the series of Sm, Eu, Tb, Dy, Er, Yb, the complexes are octa‐coordinated only by the ligand donor atoms and their coordination cages are more irregular. The formation kinetics and the acid‐assisted dissociation of several Ln^III–H₆ L complexes were investigated at different temperatures and compared with analogous data for complexes of other dota‐like ligands. The [Ce( L )(H₂O)]^3? complex is the most kinetically inert among complexes of the investigated lanthanide(III) ions (Ce, Eu, Gd, Yb). Among mixed phosphonate–acetate dota analogues, kinetic inertness of the cerium(III) complexes is increased with a higher number of phosphonate arms in the ligand, whereas the opposite is true for europium(III) complexes. According to the ¹H NMR spectroscopic pseudo‐contact shifts for the Ce–Eu and Tb–Yb series, the solution structures of the complexes reflect the structures of the [Ce(H L )(H₂O)]^2? and [Yb(H L )]^2? anions, respectively, found in the solid state. However, these solution NMR spectroscopic studies showed that there is no unambiguous relation between ³¹P/¹H lanthanide‐induced shift (LIS) values and coordination of water in the complexes; the values rather express a relative position of the central ions between the N₄ and O₄ planes.     

Hydrothermal syntheses and characterization of four 2-D lanthanide coordination polymers with glutarate and 1,10-phenanthroline

Four 2-D coordination polymers Ln₂(phen)₂(C₅H₆O₄)₃ [Ln?=?Pr(1), Eu(2), Er(3), Yb(4), phen?=?1,10-phenanthroline] were obtained via hydrothermal reactions and determined by X-ray diffraction analysis. The crystal structure data reveal that these complexes are isostructural. In the asymmetric unit, the two Ln(III) ions are nine-coordinate and have similar coordination environments. The Ln(III) ions are built into 2-D layers by three different coordination modes of glutarate. The resulting 2-D layer forms 3-D supramolecular architecture by two types of π···π stacking interactions. All the complexes were characterized by IR spectra and thermogravimetric analysis, and the emission spectrum shows that Eu₂(phen)₂(C₅H₆O₄)₃ possesses strong luminescence.     

Hydrothermal syntheses,crystal structures and luminescence properties of two lanthanide dinuclear complexes with hexafluoroglutarate

Two complexes [Ln₂(hfga)₂(phen)₄(H₂O)₆] · hfga · 2H₂O (H₂hfga = hexafluoroglutaric acid, phen = 1, 10-phenanthroline, Ln=Tb, 1; Eu, 2) were synthesized under hydrothermal conditions and their structures determined by X-ray crystallography. The complexes consist of dinuclear units with an inversion center. Each Ln(III) is nine-coordinate with two carboxylate oxygens from two hfga ligands, three oxygens from water and four nitrogens from two phen molecules. Two carboxylate groups of one hfga adopt monodentate coordination to Ln(III) as a long bidentate bridge linking two Ln(III) ions to form a dimer. Ln(III) ··· Ln(III) distances of 9.027(3) Å for 1 and 9.043(3) Å for 2 were observed. Both complexes emit strong fluorescence and show characteristic emission of Tb(III) and Eu(III) ions, respectively.     

2D l‐Di‐toluoyl‐tartaric acid Lanthanide Coordination Polymers: Toward Single‐component White‐Light and NIR Luminescent Materials

A series of five l ‐di‐p‐toluoyl‐tartaric acid (l ‐DTTA) lanthanide coordination polymers, namely {[Ln₄K⁴ L₆(H₂O)_x]?yH₂O}_n, [Ln=Dy ( 1 ), x=24, y=12; Ln=Ho ( 2 ), x=23, y=12; Ln=Er ( 3 ), x=24, y=12; Ln=Yb ( 4 ), x=24, y=11; Ln=Lu ( 5 ), x=24, y=12] have been isolated by simple reactions of H₂L (H₂L= L ‐DTTA) with LnCl₃?6 H₂O at ambient temperature. X‐ray crystallographic analysis reveals that complexes 1 – 5 feature two‐dimensional (2D) network structures in which the Ln³⁺ ions are bridged by carboxylate groups of ligands in two unique coordinated modes. Luminescent spectra demonstrate that complex 1 realizes single‐component white‐light emission, while complexes 2 – 4 exhibit a characteristic near‐infrared (NIR) luminescence in the solid state at room temperature.     

Rational design of 0D, 1D, and 3D open frameworks based on tetranuclear lanthanide(III) sulfonate-phosphonate clusters

Hydrothermal reactions of lanthanide(III) salts with m-sulfophenylphosphonic acid (H3L1) and 1,10-phenanthroline (phen) or N,N'-piperazinebis(methylenephosphonic acid) (H4L2) afforded six novel lanthanide(III) sulfonate-phosphonates based on tetranuclear clusters, namely, [La(2)(L1)2(phen)4(H2O)].4.5H2O (1), [Ln2(L1)2(phen)2(H2O)5].3H2O (Ln = Nd, 2; Eu, 3; Er, 4), and [Ln2(HL1)(H2L2)2(H2O)4].8H2O (Ln = La, 5; Nd, 6). Compounds 2-4 contain discrete tetranuclear lanthanide(III) cluster units in which four lanthanide(III) ions are bridged by two tridentate and two tetradentate phosphonate groups. In compound 1, the tetranuclear clusters are further interconnected into a 1D chain through the coordination of the sulfonate groups. The structures of compounds 5 and 6 can be viewed as a 3D architecture based on a different types of tetranuclear cluster units that are interconnected by bridging H2L2 anions. In the tetranuclear clusters of compounds 5 and 6, the four lanthanide(III) centers are interconnected by only two HL1 ligands. Compound 2 is a luminescent material in the near-IR region, whereas compound 3 displays a strong luminescent emission band in the red-light region. Magnetic property measurements of compounds 2-4 and 6 indicate that there are strong antiferromagetic interactions between magnetic centers within the cluster units.     

Hydrothermal synthesis and structural characterization of three lanthanide coordination polymers with adipic acid and 1,10-phenanthroline

Three new lanthanide coordination polymers, [Ln(Ad)_3/2(Phen)] _n ·2nH₂O (Ln = Eu, 1; Pr, 2; Ad = adipate; Phen = 1,10-phenanthroline) and [Yb(Ad)_3/2(Phen)] _n ·nH₂O 3, were prepared by hydrothermal reactions. The structures of 1, 2 and 3 are reported. In compound 1, Eu(III) ions are bridged by adipate ligands in two modes into 2-D polymeric layers. Adjacent layers are assembled by hydrogen bonding and π–π stacking between 1,10-phenanthrolines into a 3-D supramolecular structure. Compound 2 is isostructural with 1. In compound 3, the Yb(III) ions are connected by adipate ligands in three modes into a 3-D network.