The chemo-and stereo-selective two-step transformation of aliphatic polyketones composed of 3,3-dimethylpentane-2,4-dione units was achieved to generate π-conjugated polyimines. Upon treatment with hydrazine, discrete oligoketones with 4−8 carbonyl groups afforded ethylene-bridged oligoisopyrazoles in 80−89% yields. These oligoisopyrazoles underwent stereoselective oxidation at the ethylene bridge to give fully π-conjugated oligo(isopyrazole-3,5-diyl-trans-vinylene)s in 73−87% yields. Oxidation of the oligoimines drastically changed their absorption and metal-coordination behaviors. Finally, this two-step transformation was applied to polydisperse polymers. Imine formation proceeded almost quantitatively, even for longer polyketones, including docosamer. Subsequent oxidation of the polyimines furnished a virtually insoluble material that showed broad and red-shifted solid-state absorption over the whole visible region resulting from extended π-conjugation.

While solid polymer electrolytes (SPEs) have great potential for use in future lithium-based batteries, they do, however, not display conductivity at a sufficient level as compared to liquid electrolytes. To reach the needed requirements of lithium batteries it is therefore necessary to explore new materials classes to serve as novel polymer hosts. In this work, SPEs based on the polyketone poly(3,3-dimethylpentane-2,4-dione) were investigated. Polyketones are structurally similar to several polycarbonate and polyester SPE hosts investigated before but have, due to the lack of additional oxygen atoms in the coordinating motif, even more electron-withdrawing carbonyl groups and could therefore display better properties for coordination to the salt cation. In electrolyte compositions comprising 25−40 wt% LiTFSI salt, it was observed that this polyketone indeed conducts lithium ions with a high cation transference number, but that the ionic conductivity is limited by the semi-crystallinity of the polymer matrix. The crystallinity decreases with increasing salt content, and a fully amorphous SPE can be produced at 40 wt% salt, accompanied by an ionic conductivity of 3 × 10−7 S cm−1 at 32 °C. This opens up for further exploration of polyketone systems for SPE-based batteries.

Research on solid polymer electrolytes (SPEs) is now moving beyond the realm of polyethers that have dominated the field for several decades. A promising alternative group of candidates for SPE host materials is carbonyl-containing polymers. In this work, SPE properties of three different types of carbonyl-coordinating polymers are compared: polycarbonates, polyesters, and polyketones. The investigated polymers were chosen to be as structurally similar as possible, with only the functional group being different, thereby giving direct insights into the role of the noncoordinating main-chain oxygens. As revealed by experimental measurements as well as molecular dynamics simulations, the polyketone possesses the lowest glass transition temperature, but the ion transport is limited by a high degree of crystallinity. The polycarbonate, on the other hand, displays a relatively low coordination strength but is instead limited by its low molecular flexibility. The polyester performs generally as an intermediate between the other two, which is reasonable when considering its structural relation to the alternatives. This work demonstrates that local changes in the coordinating environment of carbonyl-containing polymers can have a large effect on the overall ion conduction, thereby also showing that desired transport properties can be achieved by fine-tuning the polymer chemistry of carbonyl-containing systems.

Structural convergence of the self-assembly of flexible oligoisopyrazoles was controlled by stepwise palladium coordination and discrete complexes with structural diversity were selectively generated in a predictable fashion.

Calix[3]pyrrole and its furan derivatives exhibited bathochromically shifted lowest-energy electronic transition bands in their absorption spectra compared with their calix[4]- and calix[6]-pyrrole analogues, despite the repeating units being the same. We also observed fluorescence emission for calix[3]-type macrocycles. The Stokes shift of the furan/pyrrole hybrid macrocycles, calix[2]furan[1]-pyrrole, and calix[1]furan[2]pyrrole, substantially varied depending on the solvent polarity. Non-covalent interaction (NCI) analyses indicated enhanced interactions between neighboring aromatic rings in the calix[3]pyrrole macrocycle, whereas such interactions were weak in calix[4]pyrrole, in which the interchromophore distance is remarkably longer than in calix[3]pyrrole. Theoretical analyses indicated that the red-shifted, lowest-energy bands of calix[3]pyrrole correspond to HOMO–LUMO transitions, the energy gap of which was narrow compared with calix[4]pyrroles. The characteristic absorption bands for calix[3]pyrrole and its related macrocycles are useful as probes for distinguishing such macrocycles from higher calix[[Formula: see text]]pyrrole ([Formula: see text] 4) analogues that exhibit almost identical absorption spectra.