Two histidine-templated metal phosphate-oxalates: solvent-free synthesis, luminescence, and proton-conducting properties

Two new histidine-templated metal phosphate-oxalates (MPOs) were prepared under solvent-free conditions. Single-crystal X-ray diffraction analysis reveals that they have layered and chainlike structures, respectively. Under ultraviolet light irradiation, the two MPOs exhibit blue luminescence originating from histidine templates. Their proton-conducting properties were also investigated under different conditions.

Exploration of Structured Symmetric Cyclic Peptides as Ligands for Metal-Organic Frameworks

Despite remarkable advances in the assembly of highly structured coordination polymers and metal-organic frameworks, the rational design of such materials using more conformationally flexible organic ligands such as peptides remains challenging. In an effort to make the design of such materials fully programmable, we first developed a computational design method for generating metal-mediated 3D frameworks using rigid and symmetric peptide macrocycles with metal-coordinating sidechains. We solved the structures of six crystalline networks involving conformationally constrained 6 to 12 residue cyclic peptides with C2, C3, and S2 internal symmetry and three different types of metals (Zn2+, Co2+, or Cu2+) by single-crystal X-ray diffraction, which reveals how the peptide sequences, backbone symmetries, and metal coordination preferences drive the assembly of the resulting structures. In contrast to smaller ligands, these peptides associate through peptide-peptide interactions without full coordination of the metals, contrary to one of the assumptions underlying our computational design method. The cyclic peptides are the largest peptidic ligands reported to form crystalline coordination polymers with transition metals to date, and while more work is required to develop methods for fully programming their crystal structures, the combination of high chemical diversity with synthetic accessibility makes them attractive building blocks for engineering a broader set of new crystalline materials for use in applications such as sensing, asymmetric catalysis, and chiral separation.

Self-Assembly of Cyclic Dipeptides: Platforms for Functional Materials

Supramolecular self-assembled functional materials comprised of cyclic dipeptide building blocks have excellent prospects for biotechnology applications due to their exceptional structural rigidity, morphological flexibility, ease of preparation and modification. Although the pharmacological uses of many natural cyclic dipeptides have been studied in detail, relatively little is reported on the engineering of these supramolecular architectures for the fabrication of functional materials. In this review, we discuss the progress in the design, synthesis, and characterization of cyclic dipeptide supramolecular nanomaterials over the past few decades, highlighting applications in biotechnology and optoelectronics engineering.

From an organic ligand to a metal–organic coordination polymer, and to a metal–organic coordination polymer–cocrystal composite: a continuous promotion of the proton conductivity of crystalline materials

A new strategy was proposed to increase proton conductivities in metal–organic coordination polymers (MOCPs) commencing from organic ligands, i.e. coordination inducement and MOCP–cocrystal composite formation.

Cluster–oxalate frameworks with extra-large channels: solvent-free synthesis, chemical stability, and proton conduction

Two cluster–oxalate frameworks (denoted as SCU-62 and SCU-65) were prepared under solvent-free conditions.