pH‐Switchable Inversion of the Metal‐Centered Chirality of Metallabenzenes: Opposite Stereodynamics in Reactions of Ruthenabenzene with L‐ and D‐Cysteine

Abstract

We report herein the first study on the chemical interaction between metallabenzenes and bioactive molecules. Due to its unique stereoelectronic activities, a phenanthroline-derived ruthenabenzene [Ru{CHC(PPh(3))CHC(PPh(3))CH}Cl(C(12)H(8)N(2))(PPh(3))]Cl(2) (1) selectively binds cysteine in aqueous solution at physiological pH and then undergoes a dynamic inversion of configuration at the Ru center. The structure of the L-cysteine-binding product of 1 has been determined by means of X-ray diffraction. The replacement of the L-cysteine with the D form results in an inverted stereodynamic effect. Furthermore, the inversion process of the Ru-centered configuration could be conveniently controlled by a simple pH adjustment. This is attributed to the significant influence of a special intramolecular electrostatic interaction on the dynamic epimerization process of the cysteine-binding product.

Inversion of the Supramolecular Chirality of Nanofibrous Structures through Co‐Assembly with Achiral Molecules

“…Furthermore,whereas LPF and BPy2 assembled into right-handed twisted nanoribbons (Figure 1c), the DPF-BPy2 nanofibers were formed as left-handed twisted nanoribbons ( Figure 1d). [11][12][13][14][15][16] These results were consistently obtained in several experiments. [11][12][13][14][15][16] These results were consistently obtained in several experiments.…”

“…These results suggest that nanoscale twists of opposite handedness could be generated from the same chiral molecule.T his chiral inversion was obviously triggered by achiral BPy1 and BPy2, which differs from previous approaches. [11][12][13][14][15][16] These results were consistently obtained in several experiments.…”

“…[7] On the other hand, it has remained challenging to tune the chiral conformation (right-handed, P;l eft-handed, M)o fn anostructures by achiral molecules,b ut it is very important to have an overall understanding of the assembly mechanisms of chiral nanostructures in materials science and biology. [10] Because of the non-covalent interactions,some chiral nanostructures are successfully controlled by external stimuli, such as light, [11] temperature, [12] solvent, [13] pH, [14] rotary stirring, [15] and chiral additives, [16] leading to as o-called helix-to-helix transition between P and M.H owever,i nt hese cases,c hiral guests or asymmetric factors are always present. [9] Thec hirality of supramolecular nanostructures is usually determined by the molecular chirality.…”

“…[9] Thec hirality of supramolecular nanostructures is usually determined by the molecular chirality. [10] Because of the non-covalent interactions,some chiral nanostructures are successfully controlled by external stimuli, such as light, [11] temperature, [12] solvent, [13] pH, [14] rotary stirring, [15] and chiral additives, [16] leading to as o-called helix-to-helix transition between P and M.H owever,i nt hese cases,c hiral guests or asymmetric factors are always present. In fact, chiral supramolecular structures usually do not exist alone in biological or self-assembled aggregates,b ut are closely dependent on the guests around them, which can be chiral, asymmetric, or achiral.…”

Recent Advances in Metallaaromatic Chemistry

“…[85][86][87] Metallabenzenes of one second row transition metal, ruthenium, are also known. [88][89][90][91][92][93][94] Although theoretically feasible, [16,18,95,96] the isolation of simple metallabenzenes containing other transition metals,p articularly those in the first row, has remained elusive.…”