Assembly of Surface-Confined Homochiral Helicates: Chiral Discrimination of DOPA and Unidirectional Charge Transfer

Abstract

Surface-confined double-helical polymers are generated by dynamic covalent assembly with preservation of chirality, metal coordination environment, and oxidation state of the precursor complexes. This one-step procedure involves both in solution and solution-to-surface assembly and resulted in chiral interfaces where pairs of ligands are wrapped around arrays of metal ions. In-plane XRD experiments revealed the formation of a highly ordered structure along the substrate surface. The chirality of the surfaces is expressed by the selective recognition of 3,4-dihydroxyphenylalanine (DOPA). The CD measurements show a response of the Δ-polymer-modified quartz substrates toward D-DOPA, whereas no change was observed after treatment with L-DOPA. These coordination-based interfaces assembled on metal-oxide substrates in combination with a redox-probe, [Os(bpy)3](PF6)2, in solution can resemble the behavior of a rectifier.

Chirality Control of Quadruple Helixes of Metal Strings by Peripheral Chiral Ligands

“…The control of the helical handedness, which is the D (P) or L (M) form, [1] has been rapidly developed in various fields recently, such as aromatic oligoamides, [2] polyureas [3] and coordination complexes. [4] It had been showing that the utilization of chiral groups bound at the terminal of the helical chains [5] can manipulate the chirality of these compounds, such as a camphanic group attached to the oligoamides, [6] and a chiral ferrocene bonded to the oligobenzamides. [7] In the research of EMACs (extended metal atom chains), the metal backbone is helically wrapped by four oligo-pyridylamino lignads, exhibiting either D (P) or L (M) form ( Figure 1).…”

“…The energy difference is extremely large between the D and L form of chiral EMACs with the same ligand, but is small for the racemic EMAC with achiral ligand. Furthermore, in comparison with [Ni 5 A C H T U N G T R E N N U N G (bna) 4 Cl 2 ] 2 + , the electronic delocalization of two external mixed valence [Ni 2 ] 3 + are also slightly tuned because of the partially coordinated SO 2 group. This modification of the metal-metal interaction is found by magnetism and electrochemistry.…”

Enhanced Circularly Polarized Luminescence in Emissive Charge‐Transfer Complexes

“…Gelation of functional π systems by CT interactions have been widely reported. In most cases, the gel formation required the synergistic interaction between CT interaction and some other strong interactions such as hydrogen bonding ,. In this work, CT interaction and π–π stacking could be regarded as the main driving force for the gel formation, which has rarely been reported.…”

Rerouting Electron Transfer in Molecular Assemblies by Redox‐Pair Matching

“…[10,11] Restriction of ET to one direction has been observed with redox polymers and electrodeposited films. [12][13][14][15] Electrochemical rectification using redox mediators,i ns olution or surface-adhered, has been recognized and demonstrated by Murray,B ard, and Wrighton, and their respective co-workers. [12,13,[16][17][18][19] In addition, rectification with monolayer-based transistors has been reported recently.…”