Construction of Helically Stacked π‐Electron Systems in Poly(quinolylene‐2,3‐methylene) Stabilized by Intramolecular Hydrogen Bonds

Abstract

π‐Stacked polymers, which consist of layered π‐electron systems in a polymer, can be expected to be used in molecular electronic devices. However, the construction of a stable π‐stacked structure in a polymer is considerably challenging because it requires sophisticated designs and precise synthetic methods. Herein, we present a novel π‐stacked architecture based on poly(quinolylene‐2,3‐methylene) bearing alanine derivatives as the side chain, obtained through the living cyclo‐copolymerization of an o‐allenylaryl isocyanide. In the resulting polymer, the neighboring quinoline rings of the main chain form a layered structure with π–π interactions, which is stabilized by intramolecular hydrogen bonds. The vicinal quinoline units form two independent helices and the whole molecule is a twisted‐tape structure. This structure is established on the basis of UV/CD spectra, theoretical calculations, and atomic‐force microscopy.

Chiroptical Properties in Thin Films of π-Conjugated Systems

“…This simplification does not necessarily imply poor accuracy: good to excellent agreement between calculated and experimental aggregate ECD spectra may be observed (Figure ), which is a necessary condition to make these full-QM approaches useful for a wide scope. Possible applications are multiple: accurate determination of helical handedness, including validation of exciton-based qualitative approaches; − structural assessments by employing multiple geometries, obtained by systematic variations or MD sampling; ,− interpretation of aggregate ECD spectra, for example, disentangling intrachain vs interchain mechanisms ,, or monomer chirality vs supramolecular chirality; role of short-range vs long-range couplings; , visualization of electron–hole pair densities . Furthermore, full QM calculations of vibronic spectra are feasible with the inclusion of multiple vibrational modes. ,, Finally, and very importantly, the effect of environment may be modeled accurately …”

Molecular Engineering of Water-Soluble Oligomers to Elucidate Radical π–Anion Interactions in n-Doped Nanoscale Objects

“…Similar to supramolecular polymers, noncovalent interactions among π-conjugated units embedded in the flexible backbones of oligomer scaffolds can be exploited to tune the electronic properties of nanoscale objects. − This principle has been used to engineer, for example, foldamers whose optical functions are regulated by the structural properties of the flexible chains linking the more rigid, redox-active units. − Solvent polarity and temperature are the two primary experimental handles used to parameterize noncovalent interactions between the π-conjugated units. Seminal work by Iverson and others has shown the emergence of photophysical properties unique to folding states in oligomers built from naphthalene diimide (NDI) electron-acceptor and pyrene electron donor units. − In contrast, only a few studies have explored the extent to which chemical linkages modulate the redox properties of flexible oligomers .…”

Achieving UV and X-ray Dual Photochromism in a Metal–Organic Hybrid via Structural Modulation

“…These outstanding chemical, and thermal stabilities could be associated with the π−π interactions between the conjugated TPC. 60 TmTPC-1@PVDF Membrane Fabrication. The bulk powder form of TmTPC-1 is not desirable for real-world applications, for example, radiation dosimetry and medical imaging, which require the materials to be processed into certain shapes.…”

“…In addition, PXRD studies further revealed that the structure of TmTPC-1 remains intact under different relative humidity conditions (35%, 55%, 75%, and 95%) and temperatures (100, 200, and 300 °C) (Figures S8 and S9). These outstanding chemical, radiolytic, and thermal stabilities could be associated with the π–π interactions between the conjugated TPC …”