Synthesis and Photoswitching Studies of Difurylperfluorocyclopentenes with Extended π‐Systems

Abstract

In an attempt to design molecular optoelectronic switches functioning in molecular junctions between two metal tips, we synthesized a set of photochromic compounds by extending the π-system of 1,2-bis-(2-methyl-5-formylfuran-3-yl)perfluorocyclopentene through suitable coupling reactions involving the formyl functions, thereby also introducing terminal groups with a binding capacity to gold. Avoiding the presence of gold-binding sulphur atoms in the photoreactive centre, as they are present in the frequently used analogous thienyl compounds, the newly synthesized compounds should be more suitable for the purpose indicated. The kinetics of reversible photoswitching of the new compounds by UV and visible light was quantitatively investigated in solution. The role of conformational flexibility of the π-system for the width of the UV/Vis spectra was clarified by using quantum chemical calculations with time-dependent (TD)-DFT. As a preliminary test of the potential of the new compounds to serve as optoelectronic molecular switches, monolayer formation and photochemical switching on gold surfaces was observed by using surface plasmon resonance.

Picosecond cyclization reaction dynamics of furan-based diarylethene with thiosemicarbazone side-chain groups

“…Taking into account that the determined cyclization time of СF5-TSC is close to all CF5-based DAEs studied by pump-probe spectroscopy [10,12,16] and the relaxation profile has a similar shape [9,11,13], we conclude that the exchange of thiophene against furan apparently has no impact on the ring-closing dynamics of the resulting DAE. Hence, for an application of СF5-based DAE in a combination with gold electrodes, the use of furan-based DAE will be a technical benefit, since oxygen atoms are chemically inert towards gold when compared with sulfur [25].…”

“…Both CF and OF are thermally stable, reversibly switchable and have appropriate optical properties (photoconversion quantum yields: cyclization -0.28, cycloreversion -4.910 -3 ) [25], This makes molecules attractive candidates for further applications in the molecularscaled flexible devices with optically modulated properties [4]. However, to use them in a construction of devices with a rapid optical response the dynamics of ring-closing and opening reactions have to be studied.…”

“…The thiosemicarbazone (TSC) side-chain [25] was used to connect the molecule successfully with gold electrodes [26]. Figure 1a represents photoinduced ring-closing and ring-opening (a) of CF5-TSC under consecutive UV/vis light irradiation.…”

Optical properties of gold nanoparticles decorated with furan-based diarylethene photochromic molecules

“…[24-25, 27, 31] In one previous study we focused on the synthesis of new sulphur-free photochromic molecules based on the bisfuryl-perfluorocyclopentene core connected to different anchoring groups via -extended wires. [33] The influence of the anchoring group on the electrical conductance through a single-molecule junction and the alignment of the MOs to the Fermi energy level of gold electrodes were systematically studied in a gold-break junction setup. [34][35] From this data it was concluded that for rather short molecules the nature of the anchoring group and side chain (i.e.…”

A comparative study of the fluorescence and photostability of common photoswitches in microstructured optical fibre

“…Of particular interest in this context is the use of an organic photochromic dye that can be attached to a solid support such as polymer, nanoparticles, or bulk surfaces; providing materials where surface properties such as hydrophobicity, charge, conductivity, colour, molecular recognition, and material size can be easily controlled. Such photoswitchable materials have been proposed for many applications; for example in data storage, [5] nanoelectronics, [6,7] switchable polymers, [8,9] nano-machines, [10,11] gas storage, [12] drugs, [13,14] and sensor devices [15][16][17].…”