Light-Induced Quantitative and Electrical-Field-Induced Barrierless Switching of Spiropyran Derivative on Graphite Surface

Abstract

A new class of pyridine-based spiropyran (SP) shows photoinduced reversible switching between the closed SP and ring-opened merocyanine (MC). We show that a condensed crystalline monolayer of SP on graphite can be quantitatively converted to MC upon UV irradiation. In solution only ∼10% of SP can be transformed to MC because of the establishment of a photostationary state. Using an electrical field applied by a scanning tunneling microscopy (STM) tip, single molecules are reversibly switched between SP and MC forms in their condensed phases without any threshold voltage at ambient conditions. The microscopic structure of submonolayer films of SP and MC are investigated using atomic force microscopy (AFM) and STM.

Tuning the Switching Probability of Azobenzene Derivatives on Graphite Surface through Chemical Functions

“…Unlike the expected smooth variation in the current as a function of voltage for the molecular layer, we observe several abrupt increases and decreases in the tunneling current (marked by up and down arrows). We attribute these abrupt changes in the current in the I – V curves to be originating due to reversible trans ↔ cis switching of the molecules, as reported earlier. , When conformation of the molecule changes at the tunneling junction (STM tip–molecule–graphite), the relative distance between the tip and the molecule changes and thus causes a change in the current. , To ensure that the observed jumps in current correspond to switching of molecules and not due to noise or random fluctuations, we record simultaneously I – V curves on pristine graphite surface near molecular islands. A typical I – V curve recorded on pristine graphite area is overlaid in Figure b–d (light gray curve) and show no abrupt fluctuations in tunneling current.…”

“…12,52 When conformation of the molecule changes at the tunneling junction (STM tip− molecule−graphite), the relative distance between the tip and the molecule changes and thus causes a change in the current. 15,53 To ensure that the observed jumps in current correspond to switching of molecules and not due to noise or random fluctuations, we record simultaneously I−V curves on pristine graphite surface near molecular islands. A typical I−V curve recorded on pristine graphite area is overlaid in Figure 1b−d (light gray curve) and show no abrupt fluctuations in tunneling current.…”

“…Such molecules have been demonstrated as a fundamental unit in designing electronic components such as optical memories and thin-film-based transistors . Molecular switches adsorbed on surfaces can be reversibly switched between two or more states in response to external triggers, such as light − ,electric field, − and by tunneling electrons/holes. ,− Molecular switches like azobenzene, , spiropyran, ,, and diarylethene have been well studied on the surface in their assembled layers or individually on surfaces. Among various types of molecular switches, AB and its derivatives have gained a lot of attention and can be switched between their trans and cis states in the bulk and on the surfaces. − ,− …”

Emerging Biosensors Based on Noble Metal Self‐Assembly for In Vitro Disease Diagnosis

“…Light‐induced self‐assembly is also attractive, due to the reversible assembling process. [ 56 ] To render photoresponsive self‐assembling, the key is to incorporate the metal building blocks with light‐switchable moieties (organic molecules such as spiropyran, [ 57 ] arylazopyrazoles, [ 58 ] azobenzene, [ 59 ] etc.). Functionalized on NPs through certain ligands (such as mercaptans), spiropyran, as common photoswitches, has relatively high conformational freedom, promoting the self‐assembly via covalent crosslinking upon exposure to the injected light.…”

Spiropyran-incorporated honeycomb porous films with reversible multistimuli-responsive properties

“…22 In addition to light, heat and pH, SPs can also respond to other stimuli, such as ions, solvent, electrical potential and mechanical forces. [23][24][25][26] More importantly, it was able to endow these materials with reversible coloration through physical or chemical incorporation. [27][28][29] Hence, the study of SP based stimuli-responsive materials has emerged as an exciting topic.…”