Transport properties of graphene functionalized with molecular switches

Abstract

We provide a theory of the electronic transport properties of a graphene layer functionalized with molecular switches. Our considerations are motivated by the spiropyran-merocyanine system which is non-polar in its ring-closed spiropyran form and zwitterionic in its ring-open merocyanine form. The reversible switching between these two isomers affects the carriers in graphene through the associated change in the molecular dipole moment, turning the graphene layer into a sensor of the molecular switching state. We present results for both the quasiclassical (Boltzmann) and the quantum coherent regimes of transport. Quite generally, we find a linear sensitivity of the conductance on the molecular dipole moment whenever quantum interference effects play an essential role which contrasts with a quadratic (and typically weaker) dependence when quantum interference is absent.

Interplay between TiO2 Surfaces and Organic Photochromes: A DFT Study of Adsorbed Azobenzenes and Diarylethenes

“…Numerous experimental studies have been carried out to functionalize solids with photochromes in an effort to achieve external control of the properties of the joint system; these investigations include the study of the cis−trans isomerization of ruthenium-based dyes on anatase (101) 9 and of benzylideneaniline on Au(111), 10 the rationalization of the photoexcitation of stilbenes adsorbed on TiO 2 nanoparticles, 11 as well as spyropyrans grafted on graphene substrates. 12,13 These investigations confirm that while it is possible for immobilized photochromes to retain their photochromic properties, ensuring photoisomerism is nontrivial because grafting affects the electronic, spectroscopic, and photochromic properties of the switch itself. 11,12,14 At the same time, the surface is capable of acting as a sensor of the molecular switch state, e.g., variation of the conductance or the open circuit potential of the system has been reported.…”

“…Recently, many studies have been directed toward concept devices that incorporate organic switches onto surfaces. − Because these hybrid systems are capable of exhibiting different behaviors depending upon the state of the molecular switch, they potentially lead to applications in molecular electronics and photoresponsive materials. − A particular class of molecular switches are photochromes, which are capable of undergoing light-induced isomerization. Numerous experimental studies have been carried out to functionalize solids with photochromes in an effort to achieve external control of the properties of the joint system; these investigations include the study of the cis–trans isomerization of ruthenium-based dyes on anatase (101) and of benzylideneaniline on Au(111), the rationalization of the photoexcitation of stilbenes adsorbed on TiO 2 nanoparticles, as well as spyropyrans grafted on graphene substrates. , These investigations confirm that while it is possible for immobilized photochromes to retain their photochromic properties, ensuring photoisomerism is nontrivial because grafting affects the electronic, spectroscopic, and photochromic properties of the switch itself. ,, At the same time, the surface is capable of acting as a sensor of the molecular switch state, e.g., variation of the conductance or the open circuit potential of the system has been reported. ,, …”

“…11,12,14 At the same time, the surface is capable of acting as a sensor of the molecular switch state, e.g., variation of the conductance or the open circuit potential of the system has been reported. 12,13,15 Among the variety of known photochromes, thermally reversible azobenzenes (AZBs) and light-reversible diary-lethenes have attracted substantial attention for their potential applications as building blocks of, for example, molecular motors, photochromic lenses, or nanoscale optical storage devices. 16,17 AZB (see Scheme 1) isomerizes about its azo bond between a trans and a cis configuration, with the trans isomer being well-conjugated and more stable and the cis being lessconjugated and more unstable by approximately 15 due to its twisted geometry and reduced electronic delocalization.…”

Спектрально-Кинетическое Исследование Фотохромных Систем На Основе Наноструктур Графена И Его Оксида

“…Фотохромные соединения из класса спиропиранов были использованы для ковалентной и нековалентной функционализации одностенных углеродных нанотрубок с целью создания устройств с фотоуправляемыми оптическими и электрическими свойствами [3][4][5][6][7][8][9][10]. Графен, модифицированный молекулами спиропирана с пиренсодержащим заместителем на длинном спейсере благодаря физическому π−π-взаимодействию оказался пригодным для создания оптических полевых транзисторов [11][12][13][14]. С целью использования в биологических исследованиях ОГ был модифицирован молекулами спиропирана, которые обеспечили люминесцентную визуализацию биологических объектов [15,16].…”