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Published on: July 20, 2022
Reaching optimal light-induced intramolecular spin alignment within photomagnetic molecular device prototypes
Ilaria Ciofini1, Carlo Adamo, Yoshio Teki
1Laboratoire d'Electrochimie et Chimie Analytique (CNRS UMR-7575), Ecole Nationale Supérieure de Chimie de Paris, 11, rue Pierre et Marie Curie, 75231 Paris Cedex 05, France.
Chemistry (Weinheim an Der Bergstrasse, Germany)
|November 20, 2008
Summary
Novel photomagnetic molecular devices (PMMDs) with pyrimidinyl bridges show enhanced ferromagnetic spin alignment in excited states. This improvement is due to specific molecular designs and structural distortions, paving the way for efficient molecular magnetism.
Area of Science:
- Molecular magnetism
- Organic electronics
- Computational chemistry
Background:
- Photomagnetic molecular devices (PMMDs) are crucial for advanced magnetic applications.
- Organic PMMDs utilize photosensitizers and radical spin carriers for light-induced magnetism.
- Optimizing intramolecular spin coupling is key to enhancing PMMD efficiency.
Purpose of the Study:
- Investigate ground-state (GS) and excited-state (ES) properties of novel PMMDs.
- Enhance ferromagnetic spin alignment in the lowest ES of organic PMMDs.
- Explore the role of 2-pyrimidinyl (pm) bridges in improving spin coupling.
Main Methods:
- Density functional theory (DFT) calculations were employed.
- Investigated PMMDs comprising anthracene (An) photosensitizers and imino-nitroxyl (IN) or oxoverdazyl (OV) radicals.
- Analyzed the impact of p-phenylene (ph) vs. 2-pyrimidinyl (pm) bridges on spin coupling.
Main Results:
- The use of pm bridges significantly improved the excited-state intramolecular exchange coupling (J(ES)/k(B)) by over twofold compared to ph analogues.
- Internal regio-isomers with pm bridges achieved J(ES)/k(B) values greater than +400 K.
- An optimal J(ES)/k(B) of approximately +600 K was observed, linked to a saddle-shaped structural distortion in the ES.
Conclusions:
- The [(SC)-pm-An-pm](int) pattern shows significant potential for photomagnetic applications.
- Structural distortions and electronic factors in the ES play a critical role in achieving strong spin alignment.
- These findings offer a pathway for designing more efficient organic photomagnetic materials.
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