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Reversible Switching of Spiropyran Molecules in Direct Contact With a Bi(111) Single Crystal Surface
Author(s) -
Nickel Fabian,
Bernien Matthias,
Kraffert Kai,
Krüger Dennis,
Arruda Lucas M.,
Kipgen Lalminthang,
Kuch Wolfgang
Publication year - 2017
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.201702280
Subject(s) - merocyanine , photochromism , spiropyran , materials science , molecule , molecular switch , photochemistry , van der waals force , excitation , chemical physics , ring (chemistry) , ultraviolet , crystallography , optoelectronics , nanotechnology , chemistry , organic chemistry , physics , quantum mechanics
Photochromic molecular switches immobilized by direct contact with surfaces typically show only weak response to optical excitation, which often is not reversible. In contrast, here, it is shown that a complete and reversible ring‐opening and ring‐closing reaction of submonolayers of spironaphthopyran on the Bi(111) surface is possible. The ring opening to the merocyanine isomer is initiated by ultraviolet light. Switching occurs in a two‐step process, in which after optical excitation, an energy barrier needs to be overcome to convert to the merocyanine form. This leads to a strong temperature dependence of the conversion efficiency. Switching of the merocyanine isomer back to the closed form is achieved by a temperature increase. Thus, the process can be repeated in a fully reversible manner, in contrast to previously studied nitrospiropyran molecules on surfaces. This is attributed to the destabilization of the merocyanine isomer by the electron‐donating nature of the naphtho group and the reduced van der Waals interaction of the Bi(111) surface. The result shows that molecules designed for switching in solutions need to be modified to function in direct contact with a surface.