Induced chirality at the surface: fixation of a dynamic M/P invertible helical Co3 complex on SiO2

Dynamic M/P invertible helicity was successfully induced at a SiO2 surface immobilized with a dynamic helical trinuclear cobalt complex, [LCo3(NHMe2)6](OTf)3, using chiral ((R) or (S))-1-phenylethylamine. Solid-state CD spectra and theoretical calculations suggested that the fixation of the M/P helical complex on the surface via coordination interactions was the key factor of the induced chirality at the surface.

Synthesis and applications of helical polymers with dynamic and static memories of helicity

This review mainly highlights our studies on the synthesis of one-handed helical polymers with a static memory of helicity based on the noncovalent helicity induction with a helical-sense bias and subsequent memory of the helicity approach that we developed during the past decade. Apart from the previous approaches, an excess one-handed helical conformation, once induced by nonracemic molecules, is immediately retained ("memorized") after the complete removal of the nonracemic molecules, accompanied by a significant amplification of the asymmetry, providing novel switchable chiral materials for chromatographic enantioseparation and asymmetric catalysis as well as a highly sensitive colorimetric and fluorescence chiral sensor. A conceptually new one-handed helix formation in a racemic helical polymer composed of racemic repeating units through the deracemization of the pendants is described.

Triggering the Vapochromic Behavior in C60 via the Supramolecular Wrapping of st-PMMA

Understanding the physicochemical modulation of functional molecules is the primary step in exploring novel stimuli-responsive materials, and preventing the π-π stacking configuration of π-conjugated molecules has been an effective strategy of vapochromic material development, such as of nanoporous frameworks. Nevertheless, the more complicated synthetic strategy should in fact be applied in many circumstances. In this study, we explore a facile supramolecular strategy where the commodity plastic, syndiotactic-poly(methyl methacrylate) (st-PMMA), is utilized to wrap C₆₀ to form the inclusion complex. The structural characterization revealed that C₆₀s in the st-PMMA supramolecular helix had a lower coordination number (CN = 2) compared to the face-centered-cubic packing of pure C₆₀s (CN = 12). Since the st-PMMA/C₆₀ helical complex has structural flexibility, the π-π stacking structure of C₆₀ was further interrupted by the intercalation of toluene vapors, and the complete isolation of C₆₀ in the complex induced the desired vapochromic behavior. Furthermore, the aromatic interaction between C₆₀ and aromatic solvent vapors enabled the st-PMMA/C₆₀ inclusion complex to selectively encapsulate chlorobenzene, toluene, etc., and induce the color change. The st-PMMA/C₆₀ inclusion complex exhibited a transparent film of sufficient structural integrity such that it can still induce a reversible color change after several cycles. As a result, a new strategy has been discovered for the development of novel vapochromic materials via host-guest chemistry.

Selective formation of spiroborate-based double-stranded hetero-helicates assisted by donor–acceptor interactions

A novel spiroborate-based double-stranded hetero-helicate is selectively formed through donor–acceptor interactions between the central electron-rich porphyrin and electron-deficient naphthalene diimide units.