Search results for "COPP"
showing 10 items of 3147 documents
Large Scale Synthesis of Mono- and Di-urethane Derivatives of Lysine.
1999
Orthogonally protected diurethane derivatives of lysine are valuable materials for peptide syntheses. An example is ZLys(Boc), which is exploited in the industrial production of certain well-established peptide drugs. 3,4) Another derivative is Fmoc-Lys(Boc), which is in common use in the laboratory synthesis of peptides. 5) The simplest route to these lysine derivatives seems to be using the copper complex for simultaneous protection of the a-amino and a-carboxyl function, N e -tert-butoxycarbonylation and then copper detachment. The obtained Lys(Boc) might be then subjected to N a -benzyloxycarbonylation.
Three-Dimensional Mixed-Ligand Coordination Polymers with Ferromagnetically Coupled Cyclic Tetranuclear Copper(II) Units Bonded by Weak Interactions
2011
The complexes {[Cu(HGLYO)(NO3)(bpy)]·H2O}4 (1), {[Cu(HGLYO)(NO3)(phen)]·H2O}4 (2), and [Cu(HLACO)(ClO4)(phen)]4 (3) (bpy is 2,2′-bipyridine, phen is 1,10-phenanthroline, HGLYO is monoanionic glycol...
Screening of ligands for the Ullmann synthesis of electron-rich diaryl ethers
2012
In the search for new ligands for the Ullmann diaryl ether synthesis, permitting the coupling of electron-rich aryl bromides at relatively low temperatures, 56 structurally diverse multidentate ligands were screened in a model system that uses copper iodide in acetonitrile with potassium phosphate as the base. The ligands differed largely in their performance, but no privileged structural class could be identified.
Copper complexes with dithiocarbamates derived from natural occurring amino acids. Crystal and molecular structure of [Cu(en)(EtOH)(H2O)3][Cu(dtc-pro…
2002
Abstract Reaction of Cu(II) salts with dithiocarbamates derived from the amino acids asparagine, glutamine, serine, threonine and tyrosine leads to reduction of the metallic cation and formation of Cu(I) complexes, whereas reaction with proline dithiocarbamate takes place without reduction, leading to formation of a Cu(II) coordination compound. Simultaneous reaction of proline dithiocarbamate and ethylenediamine with Cu(II) leads to the formation of the mixed complex [Cu(en)(EtOH)(H2O)3][Cu(dtc-pro)2]. In the anion, the Cu(II) centre possesses a D2h local symmetry, coordinated by two bidentate dithiocarbamate ligands, while the Cu(II) centre is in a distorted octahedral coordination in the…
Self-assembly of a chiral three-dimensional manganese(II)-copper(II) coordination polymer with a double helical architecture
2013
The use of the anionic dicopper(ii) complex, [CuII(mpba) 2]4- [mpba = N,N′-1,3-phenylenebis(oxamate)], as tetrakis(bidentate) metalloligand toward MnII ions in the presence of oxalate and the chiral (S)-trimethyl-(1-phenylethyl)ammonium cation affords the first example of a mixed oxalato/oxamato-based chiral 3D metal-organic polymer. © 2013 The Royal Society of Chemistry.
New dinuclear copper complexes incorporating bis(imidazolyl) based ligands and bidentate–monodentate oxalate bridges. Crystal structure and magnetic …
2016
Abstract This paper reports the synthesis, X-ray crystal structure and magnetic characterization of two novel copper(II) dinuclear compounds including bis(imidazolyl) ligands and oxalate anions, [Cu2(BIM)2(C2O4)2]·4H2O (1) (BIM = bis(2-imidazolyl)methane) and [Cu2(BIK)2(C2O4)2] (2) (BIK = bis(2-imidazolyl)ketone). The oxalate anion acts as bidentate–monodentate in both cases, although it exhibits different coordination bridging modes: whereas in compound 1 a μ1,1,2-oxalato is observed, a μ1,2,3-oxalato is found in compound 2. In both cases, the 3D framework is held together by a combination of H-bonding and aromatic-aromatic interactions provided by the convenient structural features of BIM…
Malonate-based copper(II) coordination compounds: Ferromagnetic coupling controlled by dicarboxylates
2003
Studies on structural and magnetic properties of polynuclear transition metal complexes, aimed at understanding the structural and chemical factors governing electronic exchange coupling mediated by multiatom bridging ligands, are of continuing interest to design new molecular materials exhibiting unusual magnetic, optical and electrical properties, bound to their molecular nature. Looking at potentially flexible bridging ligands, the malonate group seems a suitable candidate. The occurrence of two carboxylate groups in the 1,3 positions allows this ligand to adopt simultaneously chelating bidentate and different carboxylato bridging modes (syn–syn, anti–anti and syn–anti trough one or two …
Copper(II) complexes with 2,5-bis(2-pyridyl)pyrazine and oxalate and croconate: Synthesis, crystal structure and magnetic properties
2012
Abstract Two new copper(II) complexes of formula [Cu2(2,5-dpp)(C2O4)2(H2O)4] (1) and [Cu2(2,5-dpp)(C5O5)2(H2O)4]·3H2O (2) [2,5-dpp = 2,5-bis(2-pyridyl)pyrazine, C2O42− = oxalate and C5O52− = croconate (dianion of 4,5-dihydroxycyclopent-4-ene-1,2,3-trione)] have been prepared and their structures determined by X-ray crystallographic methods. Compounds 1 and 2 are dinuclear complexes where the 2,5-dpp molecule acts as a bis-bidentate bridge between the two copper(II) ions, the electroneutrality being achieved by the presence of bidentate oxalate (1) and croconate (2) ligands. Each copper(II) ion exhibits an elongated octahedral CuN2O4 environment with two nitrogen atoms from 2,5-dpp and two o…
Copper complexes modelling the interaction between benzolamide and Cu-substituted carbonic anhydrase. Crystal structure of Cu(bz)(NH3)4 complex
1998
New copper benzolamide (H 2 bz, 5-phenylsulfonamide-1,3,4-thiadiazole-2-sulfonamide) complexes with ammonia, diethylentriamine (dien) and dipropylentriamine (dipn) have been prepared. The complex [Cu(bz)(NH 3 ) 4 ] crystallises in the monoclinic space group P 2 1 / n with a = 7.621(3), b = 19.91(5), c = 11.291(3) A, β = 93.17(4)° and Z = 4. The Cu(II) is five-coordinated with an almost regular square pyramidal geometry. The dideprotonated sulfonamide behaves as monodentate ligand interacting with the metal ion through the N atom of the unsubstituted sulfonamide group. In the EPR spectrum, exchange coupling between Cu(II) polyhedra of different orientations in the unit cell is observed. The …
Modifying the reactivity of copper (II) by its encapsulation into polydimethylsiloxane: A selective sensor for ephedrine-like compounds
2018
This paper demonstrates that the reactivity of copper (II) can be modified through its entrappment in a polymeric matrix of polydimethylsiloxane (PDMS), which makes possible the reaction into the support instead of in solution. Amino-containing compounds such as amino acids, proteins and sugars, which react with Cu (II) in solution, do not react inside the polymer. As a prove of concept, a highly specific Cu (II) PDMS-based sensor for ephedrines has been developed in this work. When the sensors are put into contact with solutions of these drugs under basic conditions, a change in their color from pale green to purple is observed. This change enables the visual identification of ephedrine (E…