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Boron/Nitrogen Substitution of the Central Carbon Atoms of the Biphenalenyl Diradical π Dimer: A Novel 2e–12c Bond and Large NLO Responses
Author(s) -
Zhong RongLin,
Zhang Ji,
Muhammad Shabbir,
Hu YangYang,
Xu HongLiang,
Su ZhongMin
Publication year - 2011
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201101430
Subject(s) - diradical , chemistry , excited state , boron , atom (system on chip) , crystallography , dimer , dipole , bond length , nitrogen , single bond , ground state , atomic physics , organic chemistry , physics , crystal structure , singlet state , group (periodic table) , computer science , embedded system
On the basis of the famous staggered biphenalenyl diradical π dimer 1 , the eclipsed biphenalenyl ( 1 a ), with no centrosymmetry, was obtained by rotating a layer of 1 by 60° around its central axis. Furthermore, the central carbon atoms of 1 and 1 a were substituted by boron and nitrogen atoms to form 2 and 2 a with a novel 2e–12c bond. We found that the novel 2e–12c bond is formed by the electron pair of the occupied orbital of the phenalenyl monomer substituted by the nitrogen atom and the unoccupied orbital of the phenalenyl monomer substituted by the boron atom. As a result of the novel 2e–12c bond, 2 and 2 a exhibit a fascinating interlayer charge‐transfer transition character, which results in a significant difference in the dipole moments (Δ μ ) between the ground state and the crucial excited state. The values of Δ μ for 2 and 2 a are 6.4315 and 6.9253 Debye, clearly larger than the values of 0 and 0.0015 Debye for 1 and 1 a . Significantly, the boron/nitrogen substitution effect can greatly enhance the first hyperpolarizabilities ( β 0 ) of 2 and 2 a with a novel 2e–12c bond compared with 1 and 1 a with a traditional 2e–12c bond: 0 and 19 a.u. for 1 and 1 a are much lower than 3516 and 12272 a.u. for 2 and 2 a . Furthermore, the interaction energies ( E int )of 2 and 2 a are larger than those of 1 and 1 a , which could be considered as a signature of reliability for the newly designed dimers. Our present work will be beneficial for further theoretical and experimental studies on the properties of molecules with the novel 2e–12c bond.