Building Nanoscale Molecular Wires Exploiting Electrocatalytic Interactions

Tuning Single‐Molecule Conductance in Metalloporphyrin‐Based Wires via Supramolecular Interactions

“…Although the latter results in a robust, straightforward method to wire oligo‐porphyrins between two electrodes, the inclusion of such anchoring Scheme precludes the exploitation of other sources of supramolecular interactions that might lead to the formation of more efficient electron pathways already exploited in the natural biomolecular homologous wire. We have recently reported a novel way to form highly conductive metalloporphyrin wires by coordinating axial positions of the metalloporphyrin ring allowing to orient the ring plane perpendicularly to the electron pathway (main junction axis) . This is possible thanks to the highly axial coordinative affinity of both metal center and porphyrin ring to strong Lewis bases.…”

“…In this contribution, we aim to rationalize the conductance landscape of a metalloporphyrin‐based supramolecular wire under mechanical stress by systematically introducing structural changes of both the axial coordinative ligands and the porphyrin chemical substitution. To this goal, we built single‐molecule junctions using an STM‐break junction approach of Co II ‐porphyrins (Figure ) with different phenyl substitutions; unsubstituted ( P ), 5,15‐diphenyl ( DDP ) and 5,15‐dibisphenyl ( DBP ) substituted metalloporphyrins, employing thiol‐functionalized electrodes with two different pyridine compounds as axial coordinative linkers; a pyridine‐4‐yl‐methanethiol ( PyrMT ) and a 4‐pyridinethiol ( PyrT ). We show that this slight structural change in the axial ligands (differing by one methyl group) results in pronounced changes in the dominant supramolecular interactions that lead to the final molecular wire geometry, and ultimately dictates its final transport properties.…”

Adsorption of Expanded Pyridinium Molecules at the Electrified Interface and Its Effect on the Electron-Transfer Process

“…In this paper we report on the adsorption properties of three expanded pyridinium molecules 1 – 3 (see Chart for their chemical structures) at the electrified metal/liquid interface in order to understand the effect of adsorption on the electron-transfer mechanism within the context of the possible use of such molecules as functional building blocks for molecular electronic systems. − Single-molecule conductance values of 1 – 3 in the metal–molecule–metal junction configuration have been reported elsewhere. , The effect of solvent on single-molecule conductance and molecular junction (MJ) length values was found to be most pronounced for 1 compared to the other molecules and was tentatively attributed to its strong adsorption properties . Interestingly, MJ formation probability for 1 was 15% in mesitylene solvent and 42% in mesitylene/ethanol mixture, whereas the most probable MJ length obtained experimentally was 0.62 nm in mesitylene and 1.15 nm in mesitylene/ethanol mixture.…”

Tuning Single‐Molecule Conductance in Metalloporphyrin‐Based Wires via Supramolecular Interactions

“…[13][14][15][16][17][18] Although the latter results in ar obust, straightforward method to wire oligo-porphyrins between two electrodes,t he inclusion of such anchoring Scheme precludes the exploitation of other sources of supramolecular interactions that might lead to the formation of more efficient electron pathways already exploited in the natural biomolecular homologous wire.W eh ave recently reported an ovel way to form highly conductive metalloporphyrin wires by coordinating axial positions of the metalloporphyrin ring allowing to orient the ring plane perpendicularly to the electron pathway (main junction axis). [19][20][21] This is possible thanks to the highly axial coordinative affinity of both metal center and porphyrin ring to strong Lewis bases.Such axial ligands act as anchoring groups or linkers, [22] mimicking the common natural schemes exploited in the chemistry of photosynthetic and transmembrane electron transport. [2,3,23] In this contribution, we aim to rationalize the conductance landscape of am etalloporphyrin-baseds upramolecular wire under mechanical stress by systematically introducing structural changes of both the axial coordinative ligands and the porphyrin chemical substitution.…”

“…[2,3,23] In this contribution, we aim to rationalize the conductance landscape of am etalloporphyrin-baseds upramolecular wire under mechanical stress by systematically introducing structural changes of both the axial coordinative ligands and the porphyrin chemical substitution. To this goal, we built singlemolecule junctions using an STM-break junction approach of Co II -porphyrins (Figure 1) with different phenyl substitutions;u nsubstituted (P), 5,15-diphenyl (DDP)a nd 5,15dibisphenyl (DBP)substituted metalloporphyrins,employing thiol-functionalized electrodes with two different pyridine compounds as axial coordinative linkers;ap yridine-4-ylmethanethiol (PyrMT) [19][20][21] and a4-pyridinethiol (PyrT). We show that this slight structural change in the axial ligands (differing by one methyl group) results in pronounced changes in the dominant supramolecular interactions that lead to the final molecular wire geometry,a nd ultimately dictates its final transport properties.W ep erform extensive DFT structural and charge transport simulations of the Coporphyrin supramolecular wire using the two axial ligands to help visualizing the most plausible junction configurations in each of the studied cases.…”