Macrocyclic cis- and trans-bis(α-amino acids) and their intraannular Cu(II) complexes. Conformational in–out dichotomy and crystal packing

Novel Oxygen Chirality Induced by Asymmetric Coordination of an Ether Oxygen Atom to a Metal Center in a Series of Sugar-Pendant Dipicolylamine Copper(II) Complexes

“…Steric repulsion and an attractive force were properly used in this system. To the best of our knowledge, oxygen-atom chirality has never before been discussed explicitly, although a number of crystal structures of metal-coordinated asymmetric ethers (R−O−R‘), − including metal-bound oxygen-containing macrocycles (crown ethers or cryptands), − have been reported. In this article, controlling factors for the assembly of asymmetric oxygen atoms are discussed, including the effect of a sugar moiety, counterion, and solvent in a series of sugar-pendant dipicolylamine copper(II) complexes.…”

A Homologous Series of Persubstituted Cyclodextrin Amino Acids: The Quest for Tubular Self‐Assembly

“…Indeed, the two G4 glucose units (related by the C 2 axis) are completely submerged below the O4 mean plane, and the adjacent carboxyl groups protrude over the cyclodextrin cavity, thus closing it from one side. The two G1 glucose units are lifted above the plane, and their two ammonium groups point inside the cavity and form intramolecular hydrogen bonds with the two aforementioned proximal carboxyl groups 25…”

Synthesis, Ion Complexation Study, and 3D‐Structural Analysis of Peptides Based on Crown‐Carrier, Cα‐Methyl‐L‐DOPA Amino Acids

“…As for 3D-structural analyses, however, only two X-ray diffraction studies of single-crowned amino acids and doubly crowned 2,5-dioxopiperazines were performed. [33,34] Furthermore, these investigations, albeit of some interest, could not afford any valuable information on the preferred conformations of these residues due to the very short main-chain length of the compounds examined.…”

“…Therefore, only limited structural information on some of its peptide derivatives could be obtained. [31] Later on, other groups synthesized indane-based, [32] as well as C α -hydroxymethyl-serinebased, [33,34] achiral, C α -tetrasubstituted α-amino acid derivatives with various crown-ether side chains. As for 3D-structural analyses, however, only two X-ray diffraction studies of single-crowned amino acids and doubly crowned 2,5-dioxopiperazines were performed.…”