Bianthrone in a Single-Molecule Junction: Conductance Switching with a Bistable Molecule Facilitated by Image Charge Effects

Abstract

Bianthrone is a sterically hindered compound that exists in the form of two nonplanar isomers. Our experimental study of single-molecule junctions with bianthrone reveals persistent switching of electric conductance at low temperatures, which can be reasonably associated with molecular isomerization events. Temperature dependence of the switching rate allows for an estimate of the activation energy of the process, on the order of 120 ± 50 meV. Quantum-chemical calculations of the potential energy relief of neutral bianthrone and its anion, including identification of transition states, yields the isolated molecule isomerization barriers too high vs the previous estimate, though compatible with previous experimental studies in solution. Nevertheless, we show that the attraction of the anion in the vicinity of the metal surface by its image charge can change the energetic landscape, in particular, by significantly reducing the barrier to values compatible with the observed switching behavior.

Single-molecule electronics: from chemical design to functional devices

“…Following these experimental results, more complete theoretical modelling of charging effects on the molecular electronic spectrum has been made possible. 70,240,249,250 The effect of the solid-state environment on molecules is presented in a thorough review. 251 Recently, the effect of image charges has been confirmed in a porphyrin-type molecule using electrically gateable break junctions ( Fig.…”

A rule to distinguish diastereomeric bianthrones by 1H NMR

“…7,10,29 On the other hand, the ratios of III/IV for naturallyoccurring chrysophanol-physcion bianthrone (15), chrysophanol-isophyscion bianthrone (16), and physcion-emodin bianthrone (17) need to be conrmed by calculations (Table 1), which may be taken as valuable references for their analogues. As a result, the cis diastereomer originally assigned for 17 should be trans.…”

Dihydroazulene Photoswitch Operating in Sequential Tunneling Regime: Synthesis and Single‐Molecule Junction Studies

“…The experimental technique for fabricating the single‐molecule junction relies upon the evaporation of the molecule in ultra‐high vacuum onto a substrate with a prefabricated nanogap between silver electrodes. In addition to the recent studies on DHA 2a ,5 the technique has previously been employed successfully for studying oligo(phenylenevinylene)s15 and fullerene‐based16 and anthraquinone switches 17. The advantage of the technique is that no solution chemistry is involved during fabrication; the electrodes are deposited and the molecule is subsequently sublimed and trapped in the nanogap in the same vacuum cycle.…”