Boron‐Substituted Coronene: Intriguing Geometric and Electronic Properties, and Large Nonlinear Optical Response

Abstract

By substituting boron atoms for selected carbon atoms of a graphene quantum dot (GQD) model, namely a coronene molecule, the substituent effect on its geometric and electronic structure, as well as nonlinear optical response has been systemically investigated in theory. Our computations reveal that the boron substitution leads to a similar noncentrosymmetric apophysis structure for the boron-substituted coronene in singlet and triplet states. Noticeably, due to the small energy difference of 2.5 kcal mol between the singlet and triplet states, the boron-substituted molecule can easily be switched between the antiferromagnetic (singlet state) and ferromagnetic (triplet state) state by slightly changing the external conditions. Notably, the boron-substituted coronene exhibits a considerably large first hyperpolarizability of 36241 au, because boron substitution yields a raised structure with an intermediate singlet diradical character. Hence, it is expected that this study not only provides new insights for the boron-substituent effect on the structure and properties of graphene but also may promote practical applications of GQDs in the fields of spintronics and nonlinear optics.

Remarkable static and dynamic NLO response of alkali and superalkali doped macrocyclic [hexa-]thiophene complexes; a DFT approach

“…27 In another similar study, the reported b o of lithium doped cyclic conjugated ring system was 7.3 Â 10 3 au 33 and 3 Â 10 4 au. 34 In this study, we found that the NLO responses of alkali and superalkalis doped 6CT complexes have shown good agreement with the previously reported similar systems. 35,36 Two level model is performed to interpret the effects of change in dipole moment (Dm), oscillator strength (f o ) and crucial excited Fig.…”

“…It is postulated that NLO active material should be transparent in the interested region of EMR spectrum. 34 In order to find the adsorption wavelength of 6CT before and after doping, the UV-vis analysis is performed at TD/M05-2X/6-31+G(d,p). It is cleared from the results ( Table 3 & Fig.…”

“…It is postulated that NLO active material should be transparent in the interested region of EMR spectrum. 34 In order to nd the Fig. 2 HOMO and LUMO orbitals of 6CT, AA@6CT and SA@6CT complexes.…”

Lithiated Graphene Quantum Dot and its Nonlinear Optical Properties Modulated by a Single Alkali Atom: A Theoretical Perspective

“…Graphene (G) has a symmetric six-membered ring center and, hence, its second hyperpolarizability is quite small. The substitution of heteroatom such as boron on this central ring, however, enhances the first hyperpolarizability remarkably . Further, it was reported that the second hyperpolarizability of hexalithiobenzene (C 6 Li 6 ) is significantly large .…”

“…The substitution of heteroatom such as boron on this central ring, however, enhances the first hyperpolarizability remarkably. 25 Further, it was reported that the second hyperpolarizability of hexalithiobenzene (C 6 Li 6 ) is significantly large. 26 To increase the first hyperpolarizability, we recently studied the complexes of C 6 Li 6 with an alkali atom (M) and noticed a remarkable increase in the first static hyperpolarizability for M = Li, Na, and K. 27 This motivated us to perform an in-depth study on lithiated graphene (LiG) and investigate the effect of a single alkali atom.…”