Composition and sequence-controlled conductance of crystalline unimolecular monolayers

Abstract

Understanding how the charge travels through sequence-controlled molecules has been a formidable challenge because of simultaneous requirements in well-controlled synthesis and well-manipulated orientation. Here, we report electrically driven simultaneous synthesis and crystallization as a general strategy to study the conductance of composition and sequence-controlled unioligomer and unipolymer monolayers. The structural disorder of molecules and conductance variations on random positions can be extremely minimized, by uniform synthesis of monolayers unidirectionally sandwiched between electrodes, as an important prerequisite for the reproducible measurement on the micrometer scale. These monolayers show tunable current density and on/off ratios in four orders of magnitude with controlled multistate and massive negative differential resistance (NDR) effects. The conductance of monolayer mainly depends on the metal species in homo-metal monolayers, while the sequence becomes a matter in hetero-metal monolayers. Our work demonstrates a promising way to release an ultra-rich variety of electrical parameters and optimize the functions and performances of multilevel resistive devices.

Solid-Phase Electrosynthesis

“…Electrochemically monitoring the sequence-controlled synthesis of binary and ternary metallopolymers based on a pair of redox reactions including carbazole oxidation and vinyl reduction on terpyridine-based Os, Fe, and Ru complexes in Figure . Data from reference .…”

“…In order to achieve the precise synthesis of optoelectric polymers, the first task is overcoming reaction kinetics and statistics. As shown in Figure , we have developed solid-phase electrosynthesis. − ,, In particular, electrosynthesis accelerates the reaction kinetics at the solid–liquid interface. The similar width of self-assembled molecules and iterative monomers is favored for dynamically allowing the top-down addition during iterative reactions.…”

“…The thickness reduces and the roughness of polymer monolayer increases as a function of the densities of electroactive units on SAMs . In most cases, these metallopolymer monolayers exhibit diffraction peaks in XRD spectra, mostly corresponding to distance variations of 0.3–0.6 nm between the ligands of adjacent metallopolymers . These values are considered face-to-face and shoulder-to-shoulder distances of terpyridine or bipyridine ligands in polymer backbones.…”

“…(a–d) Length-dependence; (e) massive NDR effect; (f) rectification; (g, h, l) nonequilibrium states; (i–p) sequence-dependence; (o) memcapacitive state. Data from reference .…”

“…2023, 9, eadh0667. 4 We provided a general strategy to study the conductance of composition and sequence-controlled polymer monolayers, which showed the ultrarich variety of electrical parameters, f unctions, and performances of multilevel resistive devices.…”