Synthesis and characterization of polypropylene-graft-poly(l-lactide) copolymers by CuAAC click chemistry

The syntheses of polypropylene-graft-poly(l -lactide) copolymers (PP-g-PLAs) via copper (I)-catalyzed azide-alkyne cycloaddition “click” reaction (CuAAC) using azide side-chain functionalized polypropylene (PP-N₃) and alkyne end-functionalized poly(l -lactide) (PLA-Alkyne) were reported. The CuAAC was then applied to azide and different feeding ratios of alkyne functional polymers to give PP-g-PLAs that were characterized by FTIR, ¹H-NMR, GPC, DSC, and WCA measurements. The CuAAC click reaction was achieved by two different feeding ratio (PP-N₃:PLA-Alkyne = 1:5 and 1:10) and thermal, biodegradable, and surface properties of obtained graft copolymers were investigated. The molar ratio of PLA were calculated as 72.7 (PP-g-PLA-1) and 78.4% (PP-g-PLA-2) by ¹H-NMR spectroscopy. The water contact angle (WCA) values of PP-g-PLA-1 (81^o ± 1.3) and PP-g-PLA-2 (75^o ± 1.6) copolymers were compared with commercial chlorinated polypropylene (PP-Cl) (90^o ± 1.0), suggesting a more hydrophilic nature of desired graft copolymers produced. Conversely, the enzymatic biodegradation studies revealed that the weight losses of graft copolymers were determined as 13.6 and 22.1%, which is about 4% for commercial PP-Cl sample. Thus, it was clear that this simple and facile method was effective in promoting biodegradation of commercial polypropylene and attractive particularly for worldwide environmental remediation goals. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 2595–2601     

Synthesis, characterizations and luminescent properties of three novel aryl amide type ligands and their lanthanide complexes

Three new aryl amide type ligands, N-(phenyl)-2-(quinolin-8-yloxy)acetamide (L(1)), N-(benzyl)-2-(quinolin-8-yloxy)acetamide (L(2)) and N-(naphthalene-1-yl)-2-(quinolin-8-yloxy)acetamide (L(3)) were synthesized. With these ligands, three series of lanthanide(III) complexes were prepared: [Ln(L(1))(2)(NO(3))(2)]NO(3), [Ln(L(2))(2)(NO(3))(2)(H(2)O)(2)]NO(3).H(2)O and [Ln(L(3))(2)(NO(3))(2)(H(2)O)(2)]NO(3).H(2)O (Ln=La, Sm, Eu, Gd). The complexes were characterized by the elemental analyses, molar conductivity, (1)H NMR spectra, IR spectra and TG-DTA. The fluorescence properties of complexes in the solid state and the triplet state energies of the ligands were studied in detail, respectively. It was found that the Eu(III) complexes have bright red fluorescence in solid state. The energies of excited triplet state for the three ligands are 20325 cm(-1) (L(3)), 21053 cm(-1) (L(2)) and 22831 cm(-1) (L(1)), respectively. All the three ligands sensitize Eu(III) strongly and the order of the emission intensity for the Eu(III) complexes with the three ligands is L(3)>L(2)>L(1). It can be explained by the relative energy gap between the lowest triplet energy level of the ligand (T) and (5)D(1) of Eu(III). This means that the triplet energy level of the ligand is the chief factor, which dominates Eu(III) complexes luminescence.     

Synthesis of new copper(I)-complexed rotaxanes via click chemistry

The Cu(I)-catalyzed dipolar cycloaddition of azides and terminal alkynes (‘click’ chemistry) has been used as a mild and efficient stoppering reaction for the preparation of new copper(I)-complexed rotaxanes.     

Synthesis, structures, and luminescence properties of lanthanide complexes with structurally related new tetrapodal ligands featuring salicylamide pendant arms

To explore the relationships between the structures of ligands and their complexes, we have synthesized and characterized a series of lanthanide complexes with two structurally related ligands, 1,1,1,1-tetrakis{[(2'-(2-benzylaminoformyl))phenoxyl]methyl}methane (L(I)) and 1,1,1,1-tetrakis{[(2'-(2-picolyaminoformyl))phenoxyl]methyl}methane (L(II)). A series of zero- to three-dimensional lanthanide coordination complexes have been obtained by changing the substituents on the Pentaerythritol. Our results revealed that, complexes of the L(I) ligand, {Ln(4)L(I)(3)(NO(3))(12).nC(4)H(10)O}(infinity) (Ln = Nd, Eu, Tb, Er, n = 3 or 6)] show the binodal 3,4-connected three-dimensional interpenetration coordination polymers with topology of a (8(3))(4)(8(6))(3) notation. Compared to L(I), complexes of L(II) present a cage-like homodinuclear [Ln(2)L(II)(2)(NO(3))(6).2H(2)O].nH(2)O (Ln = Nd, Tb, Dy, n = 0 or 1) or a helical one-dimensional coordination {[ErL(II)(NO(3))(3).H(2)O].H(2)O}(infinity) polymer. The luminescence properties of the resulting complexes formed with ions used in fluoroimmunoassays (Ln = Eu, Tb) are also studied in detail. It is noteworthy that subtle variation of the terminal group from benzene to pyridine not only sensibly affects the overall molecular structures but also the luminescence properties as well.     

Crystal structures of lanthanide(III) complexes with cyclen derivative bearing three acetate and one methylphosphonate pendants

A series of lanthanide(III) complexes formulated as M[Ln(Hdo3ap)].xH(2)O (M = Li or H and Ln = Tb, Dy, Er, Lu, and Y) with the monophosphonate analogue of H(4)dota, 1,4,7,10-tetraazacyclododecane-1,4,7-triacetic-10-methylphosphonic acid (H(5)do3ap), was prepared in the solid state and studied using X-ray crystallography. All of the structures show that the (Hdo3ap)(4-) anion is octadentate coordinated to a lanthanide(III) ion similarly to the other H(4)dota-like ligands, i.e., forming O(4) and N(4) planes that are parallel and have mutual angle smaller than 3 degrees . The lanthanide(III) ions lie between these planes, closer to the O(4) base than to the N(4) plane. All of the structures present the lanthanide(III) complexes in their twisted-square-antiprismatic (TSA) configuration. Twist angles of the pendants vary in the range between -24 and -30 degrees, and for each complex, they lie in a very narrow region of 1 degree. The coordinated phosphonate oxygen is located slightly above (0.02-0.19 Angstroms) the O(3) plane formed with the coordinated acetates. A water molecule was found to be coordinated only in the terbium(III) and neodymium(III) complexes. The bond distance Tb-O(w) is unusually long (2.678 Angstroms). The O-Ln-O angles decrease from 140 degrees [Nd(III)] to 121 degrees [Lu(III)], thus confirming the increasing steric crowding around the water binding site. A comparison of a number of structures of Ln(III) complexes with DOTA-like ligands shows that the TSA arrangement is flexible. On the other hand, the SA arrangement is rigid, and the derived structural parameters are almost identical for different ligands and lanthanide(III) ions.     

Self-assembly of luminescent ternary complexes between seven-coordinate lanthanide(III) complexes and chromophore bearing carboxylates and phosphonates

Luminescent lanthanide complexes have been prepared by exploiting the interaction between lanthanide DO3A complexes and chromophore bearing carboxylates or phosphonates. This interaction can be utilised to probe the choice of sensitising chromophore suited to a given lanthanide. Furthermore, ternary complexes obtained from chromophore appended carboxylates dissociate in the presence of phosphate, while those obtained from phosphonates do not.     

New chiral lanthanide amide ate complexes for the catalysed synthesis of scalemic nitrogen-containing heterocycles

New chiral binaphthylamido yttrium and ytterbium ate complexes with lithium and potassium counterions have been synthesised and characterised. X-ray structures have been obtained for [Li(thf)4][Ln{(R)-C20H12(NC5H9)2}2] (Ln=Yb, Y) and [K(thf)5][Yb{(R)-C20H12(NCH2CMe3)2}2] as isostructural complexes. The efficiency of these complexes for the enantioselective intramolecular hydroamination was examined. [Li(thf)4][Yb{(R)-C20H12(NC5H9)2}2] afforded the highest enantiomeric excess (up to 87 %) for the synthesis of a spiropyrrolidine, while [Li(thf)4][Y{(R)-C20H12(NC5H9)2}2] proved to be slightly more active. The role of the counter cation in the active catalytic species was evidenced by the comparison between lithium and potassium ate complexes. The most active catalyst of this series, [Li(thf)4][Yb{(R)-C20H12(NCH2CMe3)2}2], was successfully used for the cyclisation of aminopentenes with internal double bonds.     

Relationship between the ligand structure and the luminescent properties of water-soluble lanthanide complexes containing bis(bipyridine) anionic arms

A series of six new ligands (L(1)-L(6)) suitable for the formation of luminescent lanthanide complexes in water is described. Ligands L(1)-L(4) are constructed from two 6'-carboxy-6-methylene-2,2'-bipyridine chromophoric arms bonded to the amino function of a 2-aminomethylene-6-carboxy-pyridine (L(1)), an N,N-diacetate-ethylene diamine (L(2)), a serine (L(3)), or an aminomalonic acid (L(4)). For ligands L(5) and L(6), the linking amino function is provided by a glutamic acid, and the anionic functions at the 6'-position of the bipyridyl arms are made of the sodium salts of monoethylphosphonic ester (L(5)) and phosphonic acid (L(6)). The synthesis and characterisation of the ligands are described, together with the study of the formation of lanthanide complexes with europium and terbium. In the case of L(3), the europium complex obtained in acidic conditions was crystallised and the X-ray crystal structure is depicted. Photophysical properties of the complexes were studied by means of UV-visible absorption, and steady-state and time-resolved luminescence spectroscopy. Excited-state luminescence lifetimes of the complexes were determined in water and deuterated water to gain insight into the number of water molecules directly coordinated in the first coordination sphere of the complexes. The coordination behaviour of the series of ligands is questioned in the light of the spectroscopic data and discussed in terms of protection of the cation towards water molecules and their impact on the luminescence efficiency.     

Synthesis of cyclopentadienyl ruthenium complexes bearing pendant chelating picolinates through an electrophilic precursor

This note reports the facile synthesis of two ruthenium cyclopentadienyl half-sandwich complexes functionalized with coordinating α-picolinates. The synthetic approach involves the (η⁵-chloromethylcyclopentadienyl)(η⁶-benzene)ruthenium(II) cation as a useful common building block for cyclopentadienyl complexes bearing anchored ligands.     

CuAAC macrocyclization: high intramolecular selectivity through the use of copper-tris(triazole) ligand complexes

A range of multivalent heteroaryl ligands, copper sources, and solvent systems have been investigated for use in CuAAC-mediated macrocyclization reactions. These studies have revealed the key factors governing selectivity for macrocyclization versus dimerization and identified a simple but specific set of reaction conditions capable of efficiently generating a diverse series of drug-like macrocycles at modest dilution in up to 95% yield.     

Synthesis and structural chemistry of oxazolinyl-carbene copper(I) complexes

Reaction of a series of directly connected oxazoline–imidazolium salts with potassium tert-butoxide and in the presence of CuBr · SMe₂ at −78 °C cleanly gave the corresponding 2-oxazolinyl-(N-mesityl)imidazolidenecopper(I) complexes which are monomeric in solution but aggregate in the solid state. X-ray diffraction studies established a dimeric structure for [{2-(4,4-dimethyl)-oxazolinyl-(N-mesityl)imidazolidene}(bromo)copper(I)]₂ (2a) whereas the chiral derivative [{2-(4-S-isopropyl)-oxazolinyl-(N-mesityl)imidazolidene}(bromo)-copper(I)]_∝ (2b) forms infinite chains of a coordination polymer.     

1,3-Dimethyl-2-phenyl-1,3-diazaphospholidine-2-oxide as ligand for the preparation of luminescent lanthanide complexes

Abstract

Europium(III) coordination compounds having general formula [Eu(β-dike)₃L₂] (β-dike?=?dibenzoylmethanate, tenoyltrifluoroacetonate; L?=?1,3-dimethyl-2-phenyl-1,3-diazaphospholidine-2-oxide) were isolated and characterized. The complexes exhibited bright red emission associated to the ⁵D₀→⁷F_J transitions of the metal center upon excitation with near-UV light, with intrinsic quantum yields around 51% and 65%, respectively, for the dibenzoylmethanate and tenoyltrifluoroacetonate derivatives. More information about the behavior of 1,3-dimethyl-2-phenyl-1,3-diazaphospholidine-2-oxide as an antenna-ligand towards trivalent lanthanide ions was obtained by its coordination to [Ln(NO₃)₃] (Ln?=?Eu, Gd, Tb) metal fragments.     

Synthesis, crystal structure, and luminescent properties of 2-(2,2,2-trifluoroethyl)-1-indone lanthanide complexes

A new β-diketone, 2-(2,2,2-trifluoroethyl)-1-indone (TFI), which contains a trifluorinated alkyl group and a rigid indone group, has been designed and employed for the synthesis of two series of new TFI lanthanide complexes with a general formula [Ln(TFI)(3)L] [Ln = Eu, L = (H(2)O)(2) (1), bpy (2), and phen (3); Ln = Sm, L = (H(2)O)(2) (4), bpy (5), and phen (6); bpy = 2,2'-bipyridine, phen = 1,10-phenanthroline]. X-ray crystallographic analysis reveals that complexes 1-6 are mononuclear, with the central Ln(3+) ion eight-coordinated by six oxygen atoms furnished by three TFI ligands and two O/N atoms from ancillary ligand(s). The room-temperature photoluminescence (PL) spectra of complexes 1-6 show strong characteristic emissions of the corresponding Eu(3+) and Sm(3+) ions, and the substitution of the solvent molecules by bidentate nitrogen ligands essentially enhances the luminescence quantum yields and lifetimes of the complexes.     

Synthesis and luminescent properties of novel lanthanide(III) beta-diketone complexes with nitrogen p,p'-disubstituted aromatic ligands

Tris-beta-diketonate lanthanide(III) complexes (Ln = Eu, Er, Yb, Tb), of general formula [Ln(acac)3 L(m)], with chelating ligands such as 4,7-disubstituted-1,10-phenanthrolines and 4,4'-disubstituted-2,2'-bipyridines, have been synthesized and fully characterized. The inductive effects of the para-substituents on the aromatic N-donor ligands have been investigated both in the solid and in the solution states. Single-crystal X-ray structures have been determined for the diethyl 1,10-phenanthroline-4,7-dicarboxylate europium and 4,4'-dimethoxy-2,2'-bipyridine erbium derivatives, revealing a distorted square antiprismatic geometry around the lanthanide atom in both cases. The influence exerted by the p,p'-substituents with respect to the nitrogen coordinating atoms on the Ln-N bond distances is discussed comparing the geometrical parameters with those found for the crystal structures containing the fragments [Ln(III)(phen)] and [Ln(III)(bipy)] obtained from the Cambridge Structural Database. The influence exerted by the electron-attracting groups on the coordination ability of the ligands, that in some cases becomes lack of coordination of the lanthanide ions, has been also detected in solution where the loss of the ligand has been followed by UV-vis spectroscopy. Moreover, the use of relatively long alkoxy chains as substituents on the 1,10-phenanthroline ligand led to the formation of a promesogenic lanthanide complex, whose thermal behavior is encouraging for the synthesis of new lanthanide liquid-crystalline species.     

Synthesis and spectral studies of copper(II) complexes with amide group ligands

Complexes of copper(II) with 2-(acetylamino)benzoic acid, 2-(benzoylamino) benzoic acid, 2-(aminocarbonyl)benzoic acid, 2-[(phenylamino)carbonyl]benzoic acid, 2-[(1-naphthalenylamino)carbonyl]benzoic acid, 2-[(2-aminophenylamino)carbonyl]benzoic acid, 2-aminobenzanilide, 2(aminobenzoyl)benzoic acid, maleanilic acid and malea-1-naphthalanilic acid have been prepared and characterized by chemical analyses, molar conductivity, magnetic susceptibility measurements, thermal data, IR, electronic and ESR spectra. The visible and ESR spectral studies of these complexes (except those of maleanilic acid and malea-1-naphthalanilic acid) indicate that they are monomeric having either square planar or distorted octahedral geometry around Cu(II). The Cu(II) complexes of maleanilic acid and malea-1-naphthalanilic acid have been tentatively assigned dimeric structures. From the ESR spectra of Cu(II) complexes various parameters have been calculated.     

Thermodynamic, kinetic and solid-state study of divalent metal complexes of 1,4,8,11-tetraazacyclotetradecane (cyclam) bearing two trans (1,8-)methylphosphonic acid pendant arms

Divalent metal complexes of macrocyclic ligand 1,4,8,11-tetraazacyclotetradecane-1,8-bis(methylphosphonic acid)) (1,8-H4te2p, H4L) were investigated in solution and in the solid state. The majority of transition-metal ions form thermodynamically very stable complexes as a consequence of high affinity for the nitrogen atoms of the ring. On the other hand, complexes with Mn2+, Pb2+ and alkaline earth ions interacting mainly with phosphonate oxygen atoms are much weaker than those of transition-metal ions and are formed only at higher pH. The same tendency is seen in the solid state. Zinc(II) ion in the octahedral trans-O,O-[Zn(H2L)] complex is fully encapsulated within the macrocycle (N4O2 coordination mode with protonated phosphonate oxygen atoms). The polymeric {[Pb(H2L)(H2O)2].6H2O}n complex has double-protonated secondary amino groups and the central atom is bound only to the phosphonate oxygen atoms. The phosphonate moieties bridge lead atoms creating a 3D-polymeric network. The [{(H2O)5Mn}2(micro-H2L)](H2L).21H2O complex contains two pentaaquamanganese(II) moieties bridged by a ligand molecule protonated on two nitrogen atoms. In the complex cation, oxygen atoms of the phosphonate groups on the opposite sites of the ring occupy one coordination site of each metal ion. The second ligand molecule is diprotonated and balances the positive charge of the complex cation. Complexation of zinc(II) and cadmium(II) by the ligand shows large differences in reactivity of differently protonated ligand species similarly to other cyclam-like complexes. Acid-assisted dissociations of metal(II) complexes occur predominantly through triprotonated species [M(H3L)]+ and take place at pH < 5 (Zn2+) and pH < 6 (Cd2+).     

Synthesis,structure, and luminescent properties of two novel polynuclear complexes of 1,3-di(pyridin-2-yl)propane-1,3-dione

Two complexes, {[Cd₆(o-dppd)₂(μ²-Cl)₆(μ³-Cl)₂(DMF)₂(H₂O)₂Cl₂]·DMF·CH₃OH} _n (I) (DMF = N,N-dimethylformamide; o-dppdH = 1,3-di(pyridin-2-yl)propane-1,3-dione) and [Cu₄(o-dppd)₂(OAc)₄(OH)₂]·4H₂O (II), were synthesised and characterised by single-crystal X-ray diffraction, elemental analysis, IR, solid fluorescence and TGA. The results showed that complex I had a rodshaped polynuclear chain with hexacoordinating Cd atoms bridged by oxygen, μ²-Cl and μ³-Cl; complex II was a tetranuclear oligomer. In general, supramolecular architectures are constructed through hydrogen-bonding and π-π stacking interactions. I shows luminescence.     

Synthesis,characterization and fluorescent properties of lanthanide complexes with two aryl amide ligands

Two aryl amide ligands, N-(p-tolyl)-2-(quinolin-8-yloxy)acetamide (L¹ ) and N-(4-chlorophenyl)-2-(quinolin-8-yloxy)acetamide (L² ), were synthesized. With these ligands, two series of lanthanide(III) complexes were prepared, Ln(L ⁿ )₂(NO₃)₃ (n = 1, 2; Ln = La, Sm, Eu, Gd, Dy), and characterized by the elemental analyses, molar conductivity, ¹H NMR spectra, IR spectra and TG-DTA. The fluorescence properties of the complexes and the triplet state energies of the ligands were studied in detail. In addition, the quantum yields of both Eu(III) complexes and Eu(L⁰)₂(NO₃)₃ [where L⁰ is N-(phenyl)-2-(quinolin-8-yloxy)acetamide] 1 Wu, WN, Yuan, WB, Tang, N, Yang, RD, Yan, L and Xu, ZH. 2006. Spectrochim. Acta A, 65: 912[Crossref], [Web of Science ®] , [Google Scholar] were calculated. The results indicate that among the lowest triplet energies (T) of the three ligands, that of L² is most suitable to the resonance level (⁵D₁) of Eu(III) ion. Furthermore, Eu(L²)₂(NO₃)₃ has the highest fluorescence intensity and quantum yield of the three Eu(III) complexes.     

Synthesis and characterization of neutral luminescent diphosphine pyrrole- and indole-aldimine copper(I) complexes

Heteroleptic copper(I) complexes of the types [Cu(N,N)(P,P)] and [Cu(N,O)(P,P)], where (P,P) = phosphine (PPh(3)) or diphosphine (dppb, DPEPHOS, XANTPHOS), (N,N) = pyrrole-2-phenylcarbaldimine, 2PyN: [Cu(2PyN)(PPh(3))(2)] (1), [Cu(2PyN) (dppb)] (2), [Cu(2PyN)(DPEPHOS)] (3), and [Cu(2PyN)(XANTPHOS)] (4), (N,N) = indole-2-phenylcarbaldimine, 2IndN: [Cu(2IndN)(DPEPHOS)] (8), and (N,O) = pyrrole-2-carboxaldehyde, 2PyO: [Cu(2PyO)(DPEPHOS)] (5), [Cu(2PyO)(XANTPHOS)] (6), or (N,O) = indole-2-carboxaldehyde, 2IndO: [Cu(2IndO)(DPEPHOS)] (7), were synthesized and characterized by multinuclear NMR spectroscopy, electronic absorption spectroscopy, fluorescence spectroscopy, and X-ray crystallography (1-3, 5-8). The complexes with aldimine ligands are thermally stable, and sublimation of 2-4 was possible at T = 230-250 °C under vacuum. All complexes exhibit long-lived emission in solution, in the solid state, and in frozen glasses. The excited states have been assigned as mixed intraligand and metal-to-ligand charge transfer (3)(MLCT + π-π*) transitions through analysis of the photophysical properties and DFT calculations on representative examples.