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Flexible, biocompatible piezoelectric materials are of considerable research interest for a variety of applications, but many suffer from low response or high cost to manufacture. Herein, novel piezoelectric force and touch sensors based on self-assembled monolayers of oligopeptides are presented, which produce large piezoelectric voltage response and are easily manufactured without the need for electrical poling. While the devices generate modest piezoelectric charge constants (d 33 ) of up to 9.8 pC N -1 , they exhibit immense piezoelectric voltage constants (g 33 ) up to 2 V m N -1 . Furthermore, a flexible device prototype is demonstrated that produces open-circuit voltages of nearly 6 V under gentle bending motion. Improvements in peptide selection and device construction promise to further improve the already outstanding voltage response and open the door to numerous practical applications., (© 2021 Wiley-VCH GmbH.)

To investigate the sequence effect on donor-acceptor conjugated oligomers and polymers, the trimeric isomers PBP and BPP, comprising dialkoxy phenylene vinylene (P), benzothiadiazole vinylene (B), and alkyl endgroups with terminal olefins, are synthesized. Sequence effects are evident in the optical/electrochemical properties and thermal properties. Absorption maxima for PBP and BPP differ by 41 nm and the electrochemical band gaps by 0.1 V. The molar emission intensity is five times greater in PBP than BPP. Both trimers are crystalline and the melting points differ by 17 °C. The PBP and BPP trimers are used as macromonomers in an acyclic diene metathesis polymerization to give PolyPBP and PolyBPP. The optical and electrochemical properties are similar to those of their trimer precursors-sequence effects are still evident. These results suggest that sequence is a tunable variable for electronic materials and that the polymerization of oligomeric sequences is a useful approach to introducing sequence into polymers., (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Electron delocalization of new mixed-valent (MV) systems with the aid of lateral metal chelation is reported. 2,2'-Bipyridine (bpy) derivatives with one or two appended di-p-anisylamino groups on the 5,5'-positions and a coordinated [Ru(bpy)(2)] (bpy = 2,2'-bipyridine), [Re(CO)(3)Cl], or [Ir(ppy)(2)] (ppy = 2-phenylpyridine) component were prepared. The single-crystal molecular structure of the bis-amine ligand without metal chelation is presented. The electronic properties of these complexes were studied and compared by electrochemical and spectroscopic techniques and DFT/TDDFT calculations. Compounds with two di-p-anisylamino groups were oxidized by a chemical or electrochemical method and monitored by near-infrared (NIR) absorption spectral changes. Marcus-Hush analysis of the resulting intervalence charge-transfer transitions indicated that electron coupling of these mixed-valent systems is enhanced by metal chelation and that the iridium complex has the largest coupling. TDDFT calculations were employed to interpret the NIR transitions of these MV systems., (Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)