Chiral Quadridentate Ligands Derived from Amino Acids and Some Zinc Complexes Thereof

Synthesis, Structures, and Redox Properties of Copper Complexes with Chiral and Achiral Amino Acid Derived Ligands

“…In agreement with the similarity of the structures, there was no significant observed difference between the spectra of 4a , 4b , and 6 . They closely resembled that of the free ligand 2 ,17 except for a 20 nm red shift of the pyridine ring π‐π* transitions,21 which appeared at 282 nm. In comparison, the corresponding free ligand signal is at 262 nm with a similar positive Cotton effect.…”

“…In comparison, the corresponding free ligand signal is at 262 nm with a similar positive Cotton effect. Interestingly, the corresponding signal of [( 2 )(H 2 O)Zn](OTf) 2 17 exhibited a negative Cotton effect with a minimum at 270 nm. The chloro complexes 8a and 8b showed different behavior, exhibiting positive signals at ca.…”

“…The quest for synthetic metalloenzyme mimetics has stimulated much interest in the characterization of weak aromatic ring/cation interactions in small coordination complexes 11−16. We have recently reported trigonal‐bipyramidal zinc complexes of the amino acid derived ligands bpaAc‐Gly‐OEt ( 1 ) and bpaAc‐Phe‐OMe ( 2 ), shown in Scheme {bpaAc = [bis(2‐picolyl)amino]acyl; Gly‐OEt = glycine ethyl ester; Phe‐OMe = phenylalanine methyl ester} 17. Intriguing features of the phenylalanine derivatives are: (i) the relatively short distance of 4.5 Å between the zinc ion and the center of the phenyl ring, and (ii) a rigid conformation of the benzyl side chain in solution.…”

Alkylzinc Complexes with Achiral and Chiral Monoanionic N,N,O Heteroscorpionate Ligands

“…Since enzymes are chiral compounds there has been a major effort in bioinorganic chemistry to supply chiral models for the active sites of metalloenzymes. Alsfasser et al9 and Vahrenkamp et al10 achieved this by including amino acids in the ligand systems. Modification of hydrotris(pyrazol‐1‐yl)borate (Tp) ligands by chiral pyrazoles derived from the chiral pool is another way to form chiral N , N , N tripod ligands.…”

The Reactivity ofN-Coordinated Amides in Metallopeptide Frameworks: Molecular Events in Metal-Induced Pathogenic Pathways?

“…We have studied some of these aspects using the novel tertiary carboxamide ligand tert ‐butoxycarbonyl‐ L ‐alanine bispicolylamide (Boc‐Ala‐bpa, 1 ), shown in Scheme . This compound belongs to a family of chelating amino acid derivatives which has been developed in our research group 22, 23. Our ligands are designed to provide a well‐defined metal binding site in combination with a weakly or noncoordinating, peptide‐analogous periphery.…”