Highly distinguishable isomeric states of a tripodal arylazopyrazole derivative on graphite through electron/hole-induced switching at ambient conditions

Manipulating the energy barrier and extending the half-life of nonequilibrium states in photochromic switches presents viable solutions for applying them in molecular electronics. Typically, the half-life of the Z isomer of azobenzene (AB) is a few days. Arylazopyrazole-based molecular switches are...

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Main Authors: Himani Malik, Sudha Devi, Debapriya Gupta, Ankit Kumar Gaur, Sugumar Venkataramani, Thiruvancheril G. Gopakumar
Format: Article
Language:English
Published: Beilstein-Institut 2025-07-01
Series:Beilstein Journal of Organic Chemistry
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Online Access:https://doi.org/10.3762/bjoc.21.112
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author Himani Malik
Sudha Devi
Debapriya Gupta
Ankit Kumar Gaur
Sugumar Venkataramani
Thiruvancheril G. Gopakumar
author_facet Himani Malik
Sudha Devi
Debapriya Gupta
Ankit Kumar Gaur
Sugumar Venkataramani
Thiruvancheril G. Gopakumar
author_sort Himani Malik
collection DOAJ
description Manipulating the energy barrier and extending the half-life of nonequilibrium states in photochromic switches presents viable solutions for applying them in molecular electronics. Typically, the half-life of the Z isomer of azobenzene (AB) is a few days. Arylazopyrazole-based molecular switches are one of the profoundly explored systems in recent times due to their superior bidirectional photoswitching and long half-life (over a thousand days at room temperature) of Z isomers. Herein, we utilize an efficient solid-state photoswitchable fluorinated tripodal N-functionalized arylazo-3,5-dimethylpyrazole derivative (FNAAP) to envisage and access multiple metastable states on the surface. The tripodal molecule forms well-ordered, large crystalline domains on graphite through non-bonding interactions between the molecules. By injecting electron/hole pairs into the self-assembled molecules on a surface using a scanning tunneling microscope (STM) tip, they are switched between 8 states (EEE, EEZ, EZE, ZEE, EZZ, ZEZ, ZZE and ZZZ) in a tunneling junction at ambient conditions. Contrary to the degeneracy-controlled four states in solution phase, all the eight states are remarkably stable on the surface and are well distinguishable by the tunneling current passing through the molecule at the tunneling junction. The change in current upon switching between these states is approximately an order of magnitude. This is particularly notable at positive sample voltage compared to negative sample voltage. The exceptional stability of the states at ambient conditions provides an opportunity to use a single FNAAP molecule as an 8-bit operation unit, with a potential storage capacity of ≈200 Tbits per 1 cm2 area using an atomically precise write and read tool like an STM tip.
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spelling doaj-art-7e2cda55204c440bb3203f7fd3de4dba2025-08-20T03:18:54ZengBeilstein-InstitutBeilstein Journal of Organic Chemistry1860-53972025-07-012111496150710.3762/bjoc.21.1121860-5397-21-112Highly distinguishable isomeric states of a tripodal arylazopyrazole derivative on graphite through electron/hole-induced switching at ambient conditionsHimani Malik0Sudha Devi1Debapriya Gupta2Ankit Kumar Gaur3Sugumar Venkataramani4Thiruvancheril G. Gopakumar5Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur 208016, UP, India Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Sector 81, SAS Nagar, Knowledge City, Manauli, Punjab, India Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Sector 81, SAS Nagar, Knowledge City, Manauli, Punjab, India Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Sector 81, SAS Nagar, Knowledge City, Manauli, Punjab, India Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Sector 81, SAS Nagar, Knowledge City, Manauli, Punjab, India Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur 208016, UP, India Manipulating the energy barrier and extending the half-life of nonequilibrium states in photochromic switches presents viable solutions for applying them in molecular electronics. Typically, the half-life of the Z isomer of azobenzene (AB) is a few days. Arylazopyrazole-based molecular switches are one of the profoundly explored systems in recent times due to their superior bidirectional photoswitching and long half-life (over a thousand days at room temperature) of Z isomers. Herein, we utilize an efficient solid-state photoswitchable fluorinated tripodal N-functionalized arylazo-3,5-dimethylpyrazole derivative (FNAAP) to envisage and access multiple metastable states on the surface. The tripodal molecule forms well-ordered, large crystalline domains on graphite through non-bonding interactions between the molecules. By injecting electron/hole pairs into the self-assembled molecules on a surface using a scanning tunneling microscope (STM) tip, they are switched between 8 states (EEE, EEZ, EZE, ZEE, EZZ, ZEZ, ZZE and ZZZ) in a tunneling junction at ambient conditions. Contrary to the degeneracy-controlled four states in solution phase, all the eight states are remarkably stable on the surface and are well distinguishable by the tunneling current passing through the molecule at the tunneling junction. The change in current upon switching between these states is approximately an order of magnitude. This is particularly notable at positive sample voltage compared to negative sample voltage. The exceptional stability of the states at ambient conditions provides an opportunity to use a single FNAAP molecule as an 8-bit operation unit, with a potential storage capacity of ≈200 Tbits per 1 cm2 area using an atomically precise write and read tool like an STM tip.https://doi.org/10.3762/bjoc.21.112azo compoundselectron/hole-induced isomerizationisomerizationmolecular switchesswitching
spellingShingle Himani Malik
Sudha Devi
Debapriya Gupta
Ankit Kumar Gaur
Sugumar Venkataramani
Thiruvancheril G. Gopakumar
Highly distinguishable isomeric states of a tripodal arylazopyrazole derivative on graphite through electron/hole-induced switching at ambient conditions
Beilstein Journal of Organic Chemistry
azo compounds
electron/hole-induced isomerization
isomerization
molecular switches
switching
title Highly distinguishable isomeric states of a tripodal arylazopyrazole derivative on graphite through electron/hole-induced switching at ambient conditions
title_full Highly distinguishable isomeric states of a tripodal arylazopyrazole derivative on graphite through electron/hole-induced switching at ambient conditions
title_fullStr Highly distinguishable isomeric states of a tripodal arylazopyrazole derivative on graphite through electron/hole-induced switching at ambient conditions
title_full_unstemmed Highly distinguishable isomeric states of a tripodal arylazopyrazole derivative on graphite through electron/hole-induced switching at ambient conditions
title_short Highly distinguishable isomeric states of a tripodal arylazopyrazole derivative on graphite through electron/hole-induced switching at ambient conditions
title_sort highly distinguishable isomeric states of a tripodal arylazopyrazole derivative on graphite through electron hole induced switching at ambient conditions
topic azo compounds
electron/hole-induced isomerization
isomerization
molecular switches
switching
url https://doi.org/10.3762/bjoc.21.112
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