Tactical response: High heterotactic stereocontrol was observed from the ring-opening polymerization of rac-lactide on using a series bis(phenolato)scandium complexes (see scheme). This appears to involve dynamic monomer-recognition process as result interconversion configuration Λ into Δ.

The ring-opening polymerization of l-lactide initiated by rare earth metal silylamido complexes [Ln(OSSO){N(SiHMe2)2}(THF)] (1−3: Ln = Y, Lu; OSSO 1, ω-dithiaalkanediyl-bridged bisphenolato) was studied. MALDI-TOF mass spectrometry and 1H NMR spectroscopy suggested that the proceeded via a conventional coordination−insertion mechanism involving silylamide ligand as initiating group cleavage acyl−oxygen bond monomer. A two-stage linear relationship between ln([LA]0/[LA]t) time observed for...

Monomeric yttrium and lutetium bis(phenolato) complexes [Ln(OSSO){N(SiHMe 2) 2}(THF)] (Ln = Y, Lu) were prepared from the reaction of silylamido [Ln{N(SiHMe 2} 3(THF) 2] with 1 equiv tetradentate 1,omega-dithiaalkanediyl-bridged bis(phenol) (OSSO)H 2 1- 9 in moderate to high yields. In contrast rigid configuration scandium analogues, 2b 3b complex 3c that contain a C bridge between two sulfur donors ligand are symmetric solution. The monomeric nature these was indicated by an X-ray...

ADVERTISEMENT RETURN TO ISSUEPREVCommunication to the...Communication the EditorNEXTHighly Active Magnesium Initiators for Ring-Opening Polymerization of rac-LactideLiying Wang and Haiyan Ma*View Author Information Laboratory Organometallic Chemistry, East China University Science Technology, 130 Meilong Road, P.O. Box 310, Shanghai 200237, P. R. China*To whom correspondence should be addressed: Fax +86 21 64253519; e-mail [email protected]Cite this: Macromolecules 2010, 43, 16,...

By combining the influence of excess alcohol, temperature and monomer-to-initiator ratios in feed, dinuclear salan aluminum complexes LRAl2Me4 exhibited a high degree control towards copolymerization L-LA ε-CL, producing blocky, gradient, tapered random copolymers.

An enantiopure zinc complex supported by an aminophenolate ligand with multiple stereogenic centers has been diastereoselectively synthesized via the variation of ortho-substituent a phenoxy moiety and N-alkyl group chiral pyrrolidinyl ring in framework, which displays high isoselectivity polymerization rac-lactide.

The preparation and characterization of several zinc magnesium complexes bearing chiral aminophenolate ligands, [(S)- or (R)-L]ZnN(SiMe3)2 (1, 2), (R)-L]ZnOtBu (3, 4) (R)-L]MgN(SiMe3)2 (5, 6) ((S)- (R)-L = (S)- (R)-2-{N-benzyl-N-[(1-nbutyl-2-pyrrolidinyl)methyl]}aminomethyl-4-methyl-6-tritylphenolate), have been reported. While the X-ray diffraction studies as well NMR spectroscopic data revealed that silylamido possess similar structures both in solid state solution, their catalytic...

Monomeric rare earth metal bis(phenolato) complexes [(Ls,s)Ln{N(SiHMe2)2}(THF)] (1a–4c) were isolated from the reaction of silylamido [Ln{N(SiHMe2)2}3(THF)x] (Ln = Sc, x 1; Ln Y, Lu, 2) and one equivalent tetradentate 1,ω-dithiaalkanediyl-bridged bis(phenol)s etbmpH2, ptbmpH2, edtbpH2 pdtbpH2 in moderate to high yields. In contrast unsymmetrical scandium 1a 3a, complex 2a, yttrium 1b 4b as well lutetium 1c–4c show Cs or C2 symmetry due relatively fast dissociation THF on NMR time scale at...

A series of aluminium alkyl complexes (BDI)AlEt2 (3a–m) bearing symmetrical or unsymmetrical β-diketiminate ligand (BDI) frameworks were obtained from the reaction triethyl and corresponding β-diketimine. The monomeric structure complex 3k was confirmed by an X-ray diffraction study, which shows that center is coordinated both nitrogen donors chelating diketiminate two ethyl groups in a distorted tetrahedral geometry. Attempt to synthesize alkoxide reactions monochloride "(BDI-2a)AlMeCl" (4)...

A series of zinc silylamido complexes bearing claw-type multidentate aminophenolate ligands, [LZnN(SiMe3)2] (L = –OAr1-CH2N[(CH2)nNR2]CH2Ar2, n 2 or 3; R Me Et (1a–3a, 5a, 7a and 8a); L –OC6H2-4,6-tBu2-2-CH2N[(CH2)2OMe]2 (9a)), have been synthesized via the reaction Zn[N(SiMe3)2]2 1 equiv. corresponding aminophenol. The with proligand L6H (2-{N-(2-methoxybenzyl)-N-[3-(N′,N′-dimethylamino)propyl]aminomethyl}-4-methyl-6-tritylphenol) resulted in formation bisphenolate complex 6 regardless...

A series of monomeric zinc silylamido complexes bearing [NNNO]-type tetradentate aminophenolate ligands, LZnN(SiMe3)2 [L = {(2-R(1))ArCH2N[(CH2)2R(2)]CH2(4-R(4)-6-R(3))C6H2O-}, R(1) NMe2, R(2) N(i)Pr2, R(3) R(4) Cl (1), cumyl (3); NEt2, (2), CPh3, Me (4); (5); (S)-1-butylpyrrolidin-2-yl, (6), (7)], have been synthesized via reactions Zn[N(SiMe3)2]2 and 1 equiv the corresponding aminophenols. The nature versatile coordination patterns these in solid state were further confirmed by X-ray...

Highly isoselective and active ring-opening polymerization of rac-lactide to obtain stereocomplexed polylactide is a long-standing challenge. In this contribution, zinc catalysts with good isoselectivities high activities (Pm = 0.87, TOF 3312 h–1 at 25 °C; Pm 0.92, 117 −20 °C, toluene) for are reported. These coordinated by well-designed chiral oxazolinyl or achiral benzoxazolyl aminophenolate ligand. Both types complexes afforded multiblock isotactic PLAs, proving be formed via chain-end...

The most important challenge in ring-opening polymerization of rac-lactide today is to obtain isotactic PLAs with high molecular weights. goal our work address this by developing novel catalysts that enable precise control over stereoselectivity and produce weight at the same time. Here we report some rare examples isoselective magnesium complexes toward ROP rac-LA, which are supported chiral oxazolinyl aminophenolate ligands. Preliminary kinetic investigations confirmed could be achieved...

A series of mono- and dinuclear salen aluminum complexes could efficiently catalyze the ROP <italic>rac</italic>-LA, producing isotactic enriched atactic PLA, respectively. In solution, association/dissociation equilibrium carbonyl group was found in model <italic>O</italic>-lactate complexes.

A series of aluminium alkyl complexes {PhC(NR′)(NR′′)}AlR2 (4a–n, R′ = 2,6-iPr2C6H3, 2,6-Me2C6H3; R′′ aryl groups with various ortho-, para- or meta-substituents, tert-butyl; R methyl, ethyl) bearing non-symmetrically N-substituted benzamidinate ligands were synthesized via the reaction trialkylaluminium and corresponding benzamidine proligands. Complex 5 symmetric amidinate ligand was also obtained for comparison purposes. The X-ray diffraction studies 4b, 4c show in each case a distorted...

Monomeric zinc silylamido and ethyl complexes bearing tetradentate aminophenolato ligands [(DNNO)ZnR] (D = NMe2, OMe; R N(SiMe3)2 (1–5, 8), Et (6, 7, 9, 10)), were isolated from the reaction of Zn[N(SiMe3)2]2 or ZnEt2 one equivalent aminophenols {aryl-CH2N[(CH2)2NMe2]CH2-phenol} in moderate to high yields. The monomeric nature these was further confirmed by X-ray diffraction studies 1, 3 10. methoxy N,N-dimethylamino group aryl unit does not coordinate with metal center solid state, only...

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A series of racemic 2-[(2′-methoxybiphenyl-2-ylimino)methyl]-4-R2-6-R1-phenols (L1H-L8H) were reacted with {Mg[N(SiMe3)2]2}2 and Ca[N(SiMe3)2]2·2THF (THF = tetrahydrofuran), respectively, to provide nine heteroleptic magnesium complexes L1–8MgN(SiMe3)2 [R1 iPr, R2 H (1a); R1 tBu, Me (2a 2a·THF); tBu (3a); CMe2Ph (4a); CPh3, (5a); 1-piperidinylmethyl, (6a); Cl, (7a); Br, (8a)], two homoleptic calcium (L2,5)2Ca (2b 5b), one complex [(L4)CaN(SiMe3)2·THF] (4b), which have been fully...

A series of magnesium silylamido complexes bearing salan-like multidentate aminophenolate ligands, [(L1–4)MgN(SiMe3)2] (1–4) and [(L1)MgN(SiHMe2)2] (1′) (L1–4 = –OAr1N(Me)(CH2)nN(Me)Ar2, n 2 or 3), have been synthesized via the reaction Mg[N(SiMe3)2]2 Mg[N(SiHMe2)2] with 1 equiv. corresponding aminophenol. The monomeric nature 1, 2, 3 main stoichiometric structure 1′ in solid state were further confirmed by X-ray diffraction studies, where four donors ligand group coordinated center...

Mono- and dinuclear salen aluminum complexes bearing a racemic 6,6′-dimethyl-biphenyl bridge could efficiently catalyze the copolymerization of <sc>l</sc>-LA ε-CL in melt, producing practically random tapered copolymers, respectively.

No-end topology provides cyclic polyesters with potential abstracting applications, but more efficient and selective routes still need to be explored access high molecular weights tacticity control. We report here that a series of aminophenolate zinc chlorides display hyperstability hyper productivity toward the ring-opening polymerization technical grade rac-lactide (rac-LA) in cyclohexene oxide, capable converting up 20,000 equiv rac-LA (TONs 18,600) polymers narrow moderate distributions...

BACKGROUND Hepatocellular carcinoma ranks among the most prevalent malignant neoplasms. Surgical intervention constitutes a critical therapeutic approach for this condition. Nonetheless, postoperative recovery is frequently influenced by patient's nutritional status and quality of nursing care provided. AIM To examine comprehensive impact personalized support strategies on rehabilitation patients with liver cancer. METHODS In study, retrospective comparative analysis was conducted involving...