Functionalized Trifluoromethyl-Containing Lithium β-Diketonate in the Synthesis of Homo- and Heteronuclear Complexes of Rare-Earth Metals

Russian Journal of Coordination Chemistry - The reactions of functionalized lithium CF3-β-diketonate (LiL) with trivalent rare-earth metal salts in methanol afford homobinuclear and...     

Synthesis and Fluorescence Properties of Thiazole-Boron Complexes Bearing a β-Ketoiminate Ligand

Novel fluorescent dyes, thiazole-boron complexes bearing β-ketoiminate ligands, have been synthesized, and their fluorescence properties were investigated. The BF(2) complexes showed a pronounced aggregation-induced emission enhancement effect because of the restriction of C-Ph intramolecular rotation. The BPh(2) complexes showed higher fluorescence quantum yields than the corresponding BF(2) complexes, both in solution and in the solid state.     

Synthesis and Structural Characterization of Lanthanide Amides Stabilized by an N-Aryloxo Functionalized β-Ketoiminate Ligand

The synthesis and characterization of dimeric lanthanide amides stabilized by a dianionic N‐aryloxo functionalized β‐ketoiminate ligand are described in this paper. Reactions of 4‐(2‐hydroxy‐5‐tert‐butyl‐phenyl)imino‐2‐pentanone (LH₂) with Ln[N(SiMe₃)₂]₃(µ‐Cl)Li(THF)₃ in a 1:1 molar ratio in THF gave the dimeric lanthanide amido complexes [LLn{N(SiMe₃)₂}(THF)]₂ [Ln=Nd ( 1 ), Sm ( 2 ), Yb ( 3 ), Y ( 4 )] in good isolated yields. These complexes were characterized by IR spectroscopy, elemental analysis, and ¹H NMR spectroscopy in the case of complex 4 . The definitive molecular structures of complexes 1 , 3 , and 4 were determined. It was found that complexes 1 to 4 can initiate the ring‐opening polymerization of L‐lactide.     

Synthesis of Two Blue-light-emitting Complexes with Schiff Base Calixarene as the Ligand

Two new blue luminescent zinc and beryllium complexes with Schiff base calixarene derivative as the ligand were prepared.Their luminescent properties were determined,which indicated that they had strong blue fluorescent properties.They also had good solubility and film formation.These new complexes can be used as blue organic electroluminescent materials (OELMs) in organic electroluminescent devices.     

Synthesis of β-Cyclodextrin Bonded Metal Porphyrins

InrecentyearsstUdyondevelopingnovelmimicenZymemodelsthathavebothoNOO-decomPositionandO,'(or.OH)dismutaseabilityisaveryactiveresearchfield1'2.Thesemodelsshowverytwrtanteffectinprovidingprotectionfromtissuedamageassociatedwithvariousmpesofinfiammatorydiseases.MetallopoIPhyrinsassuPeroxidedismutase(SOD)mimicshaveshowedtheabilitytocatalysttheseharmfulradicals.Groveandco-workersrePorted[Mn(III)TMPyP]and[Fe(III)TMPyP]whichhaveshowedveryefficientbehaviorasperoxynitritereductaseandcandep…     

A Convenient Procedure for the Synthesis of 6-O-Mono-Phosphate β-Cyclodextrins

Abstract

The synthesis of β-cyclodextrin derivatives bearing one phosphate group on the primary rim is reported. These compounds were prepared in good to excellent yields, by reacting β-cyclodextrin with dialkyl chlorophosphates in the presence of 4-dimethyl amino pyridine (DMAP) catalyst and dimethylformamide (DMF) as solvent. The methodology described is highly selective and the purification of the title compounds is simple, because difficulties due to phosphate regioisomers mixture are avoided.     

Retro-Claisen Cleavage of the β-Dicarbonyl Ligand in Alcoholysis of Group IVB Metal Chelates

Chelates of titanium, zirconium, and hafnium with -dicarbonyl compounds react with butyl, amyl, and octyl alcohols to give metal alkoxides. The reaction is accompanied by retro-Claisen cleavage of the ligand. The reactivity of the chelates was studied in relation to the ligand structure, nature of the metal, and reaction temperature. The reaction mechanism is discussed.     

Continuous Flow Synthesis of Metal–NHC Complexes**

The use of weak bases and mild conditions is currently the most sustainable and attractive synthetic approach for the preparation of late-transition metal complexes, some of which are widely used in catalysis, medicinal chemistry and materials science. Herein, the use of cuprate, aurate or palladate species for a continuous flow preparation of Cu^I, Au^I and Pd^II-NHC complexes is reported. All reactions examined proceed under extremely mild conditions and make use of technical grade acetone as solvent. The scalability of the process was exemplified in a multigram-scale synthesis of [Cu(IPr)Cl].     

Calixthiacrown:A New Multidentate Ligand for Platinum Metal

CalixarenesareafamilyofcyclicoligmerspreparedfromfOrmaldehydeandpara-substitutedphenolsviacycliccondensationunderalkalineconditions.Itwassuggestedthatthecalixarenescanbecountedasthethirdhostmoleculeorthethirdgenerationofsupramolecules,aftercrownethersandcyclodextrinst,,,j.TbeycanbeusedaspIatformsorbuildingblockstoconstructaseriesofcompoundsbavingpreorganizedstructures.Whencalixareneswerebridgedbypolyoxyetbylenecbainintra-orintermolecularyly,cal-.ixcrownswereobtained.Someofthelatterexhibitedou…     

Synthesis of Metal‐Free Phthalocyanines in Functionalized Ammonium Ionic Liquids

A convenient, fast, efficient, and ecofriendly synthesis of metal‐free phthalocyanines from various substituted phthalonitriles in different hydroxyalkylammonium ionic liquids in the presence of 1,8‐diazabicyclo‐[5,4,0]‐undec‐7‐ene (DBU) is reported in moderate yields. The effect of concentration of DBU and temperature on the synthesis of phthalocyanine in N‐(2‐hydroxyethyl)‐N,N‐dimethylbutylammonium bromide ionic liquid has been examined, and the ionic liquid has been recovered and reused conveniently.     

Synthesis and Crystal Structure of the Novel Chiral o—Hydroxyphenyloxazoline Metal Complexes

1 INTRODUCTION Optically active oxazolines have been extensi- vely used as valuable chiral ligands for transition metals in asymmetric catalysis[1]. The design and syntheses of new chiral oxazoline ligands have inspired many scientists to work with great efforts during the recent years. Our interest has been focus- ed on the studies of enantioselective transition- metal catalysis of heterocyclic ligands. In the pre- sent work, we choose o-hydroxyphenyloxazoline ligand for it has a rigi…     

Dissociation of Multisubunit Protein–Ligand Complexes in the Gas Phase. Evidence for Ligand Migration

The results of collision-induced dissociation (CID) experiments performed on gaseous protonated and deprotonated ions of complexes of cholera toxin B subunit homopentamer (CTB₅) with the pentasaccharide (β-D-Galp-(1→3)-β-D-GalpNAc-(1→4)[α-D-Neu5Ac-(2→3)]-β-D-Galp-(1→4)-β-D-Glcp (GM1)) and corresponding glycosphingolipid (β-D-Galp-(1→3)-β-D-GalpNAc-(1→4)[α-D-Neu5Ac-(2→3)]-β-D-Galp-(1→4)-β-D-Glcp-Cer (GM1-Cer)) ligands, and the homotetramer streptavidin (S₄) with biotin (B) and 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine-N-(biotinyl) (Btl), are reported. The protonated (CTB₅ + 5GM1)ⁿ⁺ ions dissociated predominantly by the loss of a single subunit, with the concomitant migration of ligand to another subunit. The simultaneous loss of ligand and subunit was observed as a minor pathway. In contrast, the deprotonated (CTB₅ + 5GM1)^n- ions dissociated preferentially by the loss of deprotonated ligand; the loss of ligand-bound and ligand-free subunit were minor pathways. The presence of ceramide (Cer) promoted ligand migration and the loss of subunit. The main dissociation pathway for the protonated and deprotonated (S₄ + 4B)^n+/– ions, as well as for deprotonated (S₄ + 4Btl)^n– ions, was loss of the ligand. However, subunit loss from the (S₄ + 4B)ⁿ⁺ ions was observed as a minor pathway. The (S₄ + 4Btl)ⁿ⁺ ions dissociated predominantly by the loss of free and ligand-bound subunit. The charge state of the complex and the collision energy were found to have little effect on the relative contribution of the different dissociation channels. Thermally-driven ligand migration between subunits was captured in the results of molecular dynamics simulations performed on protonated (CTB₅ + 5GM1)¹⁵⁺ ions (with a range of charge configurations) at 800 K. Notably, the migration pathway was found to be highly dependent on the charge configuration of the ion. The main conclusion of this study is that the dissociation pathways of multisubunit protein–ligand complexes in the gas phase depend, not only on the native topology of the complex, but also on structural changes that occur upon collisional activation.

Metal Complexes of Donor-functionalized Fluorinated β-Ketoiminates – Synthesis,Structure, and CVD Application

Six alkali metal complexes of partly-fluorinated, donor-functionalized β-ketoiminate ligands [L¹Li ( 1 ), L¹Na ( 2 ), L¹K ( 3 ), L¹Cs ( 4 ), L¹ = OC(CF₃)CHC(CH₃)NCH₂CH₂OCH₃; L²Li ( 5 ), L²Na ( 6 ), L² = OC(CF₃)CHC(CH₃)NCH₂CH₂N(CH₃)₂] were prepared and structurally characterized. Reactions of L¹Li with PtCl₂ gave the homoleptic Pt complex L¹₂Pt ( 7 ), which was characterized spectroscopically and by single-crystal X-ray diffraction and whose promising application as CVD precursor (chemical vapor deposition) is shown. Polycrystalline, pure Pt films were grown at 500 °C on SiO₂@Si(100) substrates at 10^–3 mbar and characterized by XRD, SEM, AFM, EDX and XPS.     

Novel Method for the Enantioselective Synthesis of β-Lactams

A novel method for the enantioselective synthesis of β-lactams is described in this study. 2,3-Dihydrobenzooxazin-4-one derived from salicylamide and L-menthone was used as the chiral auxiliary, which reacted with a-bromo-acyl bromides in the presence of pyridine to give carboximides 2. The stereo-controlled Reformatsky-type reactions of carboximides with imines yielded the corresponding trans β-lactams with high enantioselectivities（e.e. 75%-86%） and high chemical yields（63%-85%）, meanwhile, the chiral auxiliary dihydrobenzooxazin-4-one was released and recovered.     

Novel Method for the Enantioselective Synthesis of β-Lactams

A novel method for the enantioselective synthesis of β-lactams is described in this study.2,3-Dihydrobenzooxazin-4-one derived from salicylamide and L-menthone was used as the chiral auxiliary, which reacted with α-bromo-acyl bromides in the presence of pyridine to give carboximides 2. The stereo-controlled Reformatsky-type reactions of carboximides with imines yielded the corresponding trans β-lactams with high enantioselectivities(e.e. 75%-86%) and high chemical yields(63%-85%), meanwhile, the chiral auxiliary dihydrobenzooxazin-4-one was released and recovered.     

Synthesis of Some Polymer‐Metal Complexes and Elucidation of their Structures

In this study, the nine coordination polymers of Fe(III), Co(II) and Ni(II) salts have been synthesized using polyacrylamide (PAA), polt(ethylene glycol) (PEG) and poly(vinyl alcohol) (PVA) and their structures were characterized by magnetic and conductivity measurements, ultraviolet‐visible (UV‐VIS), FTIR spectroscopy and thermogravimetric analysis (TGA). The structures of Fe(III) complexes in the all coordination polymers were found as tetrahedral. The structures of PAA‐Co(II) coordination polymer was determined as octahedral geometry whereas PEG‐Co(II) and PVA‐Co(II) complexes showed as tetrahedral structure. PAA‐Ni(II) and PEG‐Ni(II) complexes have octahedral geometry, whereas PVA‐Ni(II) has a square planar structure. Besides, the stress‐strain experiments of PVA‐metal coordination polymers obtained rubber‐like structure were carried out and the value of breaking‐strain of PVA‐Ni(II) complex was found to be about 17% of vulcanized natural rubber. The conductivities of the resulting polymer‐metal complexes were measured by four‐probe technique and were found in the range 10^?5?10^?6 Scm^?1. Thus, it was suggested that they can be used in the field potential application of conducting polymers. TGA results revealed that among the complexes PEG‐Fe(III) and PVA‐Fe(III) complexes have the highest thermally stable.     

Pyrrole-Protected β-Aminoalkylzinc Reagents for the Enantioselective Synthesis of Amino-Derivatives

Chiral β-aminoalkylzinc halides were prepared starting from optically pure commercial β-amino-alcohols. These amino-alcohols were converted to the corresponding N-pyrrolyl-protected alkyl iodides which undergo a zinc insertion in the presence of LiCl (THF, 25 °C, 10–90 min). Subsequent Negishi cross-coupling or acylation reactions with acid chlorides produced amino-derivatives with retention of chirality. Diastereoselective CBS-reductions of some prepared N-pyrrolyl-ketones provided 1,3-subsituted N-pyrrolyl-alcohols with high diastereoselectivity. Additionally, a deprotection procedure involving an ozonolysis allowed the conversion of the pyrrole-ring into a formamide without loss of optical purity.     

Use of Crown Ether Functions as Secondary Coordination Spheres for the Manipulation of Ligand–Metal Intramolecular Electron Transfer in Copper–Guanidine Complexes

Intramolecular electron transfer (IET) between a redox-active organic ligand and a metal in a complex is of fundamental interest and used in a variety of applications. In this work it is demonstrated that secondary coordination sphere motifs can be applied to trigger a radical change in the electronic structure of copper complexes with a redox-active guanidine ligand through ligand–metal IET. Hence, crown ether functions attached to the ligand allow the manipulation of the degree of IET between the guanidine ligand and the copper atom through metal encapsulation.     

A Convenient Synthesis of β-Ketosulfoxides

β-Ketosulfoxideshaveattractedmanyorganicchemistsbecauseoftheirwideuseinsynthesisofketones,a-ketols,glyoxals,a-ketoacids,glycols,a-hydroxyacidsandsoculGenerally,6-ketosulfoxidescanbepreparedbythereactionofesterwithsulfoxidel',acylchloridewithsulfoxi...