Mixed superalkalis are a better choice than pure superalkalis for B12N12 nanocages to design high-performance nonlinear optical materials

Rehana Bano; Khurshid Ayub; Tariq Mahmood; Muhammad Arshad; Ahsan Sharif; Sobia Tabassum; Mazhar Amjad Gilani

doi:10.1039/d2dt00321j

Mixed superalkalis are a better choice than pure superalkalis for B₁₂N₁₂ nanocages to design high-performance nonlinear optical materials

Dalton Trans. 2022 May 31;51(21):8437-8453. doi: 10.1039/d2dt00321j.

Authors

Rehana Bano¹, Khurshid Ayub², Tariq Mahmood^{2

3}, Muhammad Arshad⁴, Ahsan Sharif¹, Sobia Tabassum⁵, Mazhar Amjad Gilani⁶

Affiliations

¹ School of Chemistry, University of the Punjab, Lahore-54590, Pakistan.
² Department of Chemistry, COMSATS University Islamabad, Abbottabad Campus, Abbottabad-22060, Pakistan.
³ Department of Chemistry, College of Science, University of Bahrain, P.O. Box 32038, Bahrain.
⁴ Institute of Chemistry, The Islamia University of the Bahawalpur, Bahawalpur-63100, Pakistan.
⁵ Interdisciplinary Research Centre in Biomedical Materials (IRCBM), COMSATS University Islamabad, Lahore Campus, Lahore-54600, Pakistan.
⁶ Department of Chemistry, COMSATS University Islamabad, Lahore Campus, Lahore-54600, Pakistan. mazhargilani@cuilahore.edu.pk.

PMID: 35593348
DOI: 10.1039/d2dt00321j

Abstract

Mixed superalkali clusters are a source of excess electrons, as their vertical ionization energies (2.81-3.36 eV) are much lower than those of alkali metals (even cesium (∼3.85 eV)) and the superalkali Li₃O (3.42 eV). In the present work, the geometric, electronic, and nonlinear optical (NLO) properties of mixed superalkali cluster-doped B₁₂N₁₂ nanocages are studied theoretically. All complexes, A-G, have very high interaction energies (-98.02 to -123.13 kcal mol^-1) and are thermodynamically stable when compared to previously reported Li₃O@B₁₂N₁₂ (-92.71 kcal mol^-1). The designed complexes have smaller HOMO-LUMO energy gaps (3.36-4.27 eV) than pristine B₁₂N₁₂ (11.13 eV). Charge transfer in the complexes is studied through natural population analysis and non-bonding interactions are evaluated through quantum theory of atoms in molecules (QTAIM) and non-covalent interaction analyses. These complexes have absorption maxima (1076-1486 nm) in the near-infrared region (NIR) and they are transparent in the UV region. The first hyperpolarizability of complex C is 1.7 × 10⁷ au, which is much higher than the value of 3.7 × 10⁴ au for a pure Li₃O superalkali-doped B₁₂N₁₂ complex calculated at the same level of theory, as reported by Sun et al. (Dalton Trans., 2016, 45, 7500-7509). The large second hyperpolarizability values also reflect the enhanced nonlinear optical response. The best computed values for the electro-optical Pockels effect, second harmonic generation, and hyper-Rayleigh scattering are 3.29 × 10¹⁰ au, 1.17 × 10¹⁰ au, and 6.71 × 10⁶ au, respectively. Furthermore, the electro-optic dc-Kerr effect and electric-field-induced second harmonic generation have maximum values of 3.96 × 10¹¹ au and 3.46 × 10¹⁰ au at 1064 nm. There are enhancements in the quadratic nonlinear refractive index (n₂) values for complexes A-G, with a highest n₂ value of 3.35 × 10^-8 cm² W^-1 at 1064 nm. These results suggest that mixed-superalkali-doped B₁₂N₁₂ nanoclusters are potential candidates when designing high-performance NLO materials.