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Theoretical Perspective on Two-State "ON-OFF" NLO Switch of Rh(III)-Azobenzene Complex with Considerable First
Huiying Wang1,2, Feiwu Chen1,2
1Department of Chemistry and Chemical Engineering, School of Chemistry and Biological Engineering, University of Science and Technology Beijing, Beijing 100083, China.
The Journal of Physical Chemistry. A
|June 5, 2023
Summary
This study analyzes Rh(III)-azobenzene complexes, finding that the trans-form shows enhanced charge separation and π-conjugation. These complexes exhibit significant nonlinear optical (NLO) properties, suggesting potential optoelectronic applications.
Area of Science:
- Computational Chemistry
- Materials Science
- Optoelectronics
Background:
- Azobenzene complexes are known for their photoisomerization capabilities.
- Rh(III) complexes offer unique electronic and geometric properties.
- Understanding structure-property relationships is crucial for designing advanced materials.
Purpose of the Study:
- To investigate the geometrical and electronic structure of light-induced Rh(III)-azobenzene complexes in cis- and trans-conformations.
- To analyze the linear and second-order nonlinear optical (NLO) properties.
- To explore their UV-vis absorption spectra for potential optoelectronic applications.
Main Methods:
- Density Functional Theory (DFT) calculations were employed.
- Analysis of geometrical and electronic structure.
- Calculation of NLO properties (first hyperpolarizability, βtot) and UV-vis absorption spectra.
Main Results:
- Trans-Rh conformation exhibits superior charge separation and π-conjugation compared to cis-Rh.
- Both cis- and trans-Rh conformations display unusually small energy gaps (0.28-0.36 eV), facilitating electronic transitions.
- Considerable second-order NLO responses were observed, with βtot values up to 8.5 × 10⁴ a.u. for trans-Rh (ON state).
- A switchable ratio of 1.2 for βtot indicates clear switching characteristics.
- UV-vis spectra show distinct absorption peaks in UV (cis-Rh, 301 nm) and visible (trans-Rh, 446 nm) regions, allowing for tunable absorption.
Conclusions:
- The studied Rh(III)-azobenzene complexes possess significant NLO properties due to their electronic structure and small energy gaps.
- The distinct absorption profiles of cis- and trans-forms enable tunable optical responses.
- These findings highlight the potential of Rh(III)-azo complexes for optoelectronic devices.
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