Multilithiation Effect on the First Hyperpolarizability of Carbon–Boron

Article pubs.acs.org/JPCC

Multilithiation Effect on the First Hyperpolarizability of Carbon− Boron−Nitride Heteronanotubes: Activating Segment versus Connecting Pattern Rong-Lin Zhong, Shi-Ling Sun, Hong-Liang Xu,* Yong-Qing Qiu,* and Zhong-Min Su Institute of Functional Material Chemistry, Faculty of Chemistry, Northeast Normal University, Changchun, 130024 Jilin, People’s Republic of China S Supporting Information *

ABSTRACT: Recently, the N-connecting pattern of the BN-segment has been shown as a suitable strategy to enhance the static first hyperpolarizability (β0) of carbon−boron− nitride heterojunction nanotubes (J. Phys. Chem. C 2013, 117, 10039−10044). In this work, we report a quantum chemical investigation on the lithiation effect to further reveal the mechanism of modification. Interestingly, the lithiation effect is significantly dependent on the activating segment of the heterojunction nanotubes. For lithiation on the BN-segment, the β0 (3.22 × 104 au) of Li5−BN-1a is larger than that (1.42 × 104 au) of Li5−BN-2a, which shows that the N-connecting pattern of the BN-segment linking to the C-segment is an efficient way to enhance the β0 of heterojunction nanotubes. However, for lithiation on the C-segment, the β0 (6.03 × 104 au) of Li5−BN-1b is even slightly smaller than that (6.97 × 104 au) of Li5−BN-2b. Besides, results show that activating the C-segment is a more effective strategy than activating the BN-segment for enhancing the β0 of carbon− boron−nitride heterojunction nanotubes by lithiation. The new knowledge about heterojunction nanotubes might provide important information for designing nonlinear optical molecules by rationally introducing lithium atoms on carbon−boron−nitride heterojunction nanotubes.

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Scheme 1. Structure of Heterojunction Nanotube Fragements BN-1 and BN-2

INTRODUCTION In the past few years, carbon−boron−nitride heterojunction nanotubes1−6 have attracted an increasing number of scientists to exploit and develop the fascinating properties of the novel nanostructures. Generally, carbon−boron−nitride heterojunction nanotubes are known as doping BN-segments into C-segments with different formation proportions and connecting patterns.7 Recently, a large number of investigations8−13 on BN-segments doped carbon nanotubes14,15 (CNTs) show that their electronic properties obviously depend on the arrangement and relative concentration of BN over C atoms. In particular, Turner and co-worker16 show that the highest occupied molecular orbital−lowest unoccupied molecular orbital (HOMO−LUMO) energy gap of the heterojunction nanotubes could be tuned by modifying the C/BN combinations. Correspondingly, our recent study17 indicates that for the circularly doped mode the N-connecting pattern of the BN-segment linking to the C-segment (BN-1 in Scheme 1) is an efficient way to decrease the transition energy which might be a suitable strategy to enhance the nonlinear optical (NLO) response of heterojunction nanotubes. Up to now, great efforts have been devoted to design and synthesize high-performance NLO molecules due to their potential applications in laser devices.18−34 It is worthy of note that the static first hyperpolarizability (β0) is the microscopic parameter of the macroscopic second NLO response of materials, which could be effectively adjusted by many strategies.25,32 For example, the reported strategies to enhance © 2014 American Chemical Society

β0 include the use of molecules with abundant π-electrons,35−37 the introduction of donor/acceptor groups,38−40 and incorporation of a transition metal atom with organic compounds,23,41,42 etc. Recently, the lithiation effect on the β0 of the acene system43 and supershort single-walled carbon nanotubes44 has been Received: April 2, 2014 Revised: June 1, 2014 Published: June 4, 2014 14185

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Figure 1. Optimized structures of Li5−BN-1a, Li5−BN-2a, Li5−BN-1b, and Li5−BN-2b.

investigated by our group. Results show that the lithiation effect plays an important role in enhancing the β0 of acenes43 and supershort single carbon nanotubes.44 However, the lithiation effect on corresponding properties of heterojunction nanotubes is rarely reported though they have caught an increasing amount of attention.11,17,45,46 Paying further attention to the lithiation effect on the β0 of heterojunction nanotubes might open new perspectives to develop their further applications in nanotechnology.17 In this paper, we report a quantum chemical investigation on the lithiation effect of heterojunction nanotubes to reveal the mechanism of modification. As shown in Figure 1, Li5−BN-1a/ Li5−BN-2a is constructed by activating the BN segment (substituting the five hydrogen atoms with lithium atoms) in BN-1/BN-2.17 On the other hand, Li5−BN-1b/Li5−BN-2b is obtained by activating the C segment in BN-1/BN-2. Results show that for lithiation on the BN-segment the β0 of Li5−BN-1a is larger than that of Li5−BN-2a. However, for lithiation on the C-segment, the β0 of Li5−BN-1b is 6.03 × 104 au, which is slightly smaller than that (6.97 × 104 au) of Li5−BN-2b. Besides, activating the C-segment is more effective than activating the BN-segment for enhancing the β0 of carbon−boron−nitride heterojunction nanotubes by lithiation. The new knowledge about the lithiation effect might provide important information for designing NLO molecules by introducing lithium atoms into carbon−boron−nitride heterojunction nanotubes rationally.

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Table 1. First Hyperpolarizabilities (β0) Calculated by Different Density Functionals CAM-B3LYP BHandHLYP M06 M06-2X B3LYP PBE0

Li5−BN-1a

Li5−BN-2a

Li5−BN-1b

Li5−BN-2b

3.22 × 104 3.76 × 104 4.07 × 104 3.11 × 104 4.67 × 104 3.92 × 104

1.42 × 104 1.83 × 104 3.76 × 104 1.58 × 104 3.39 × 104 2.13 × 104

6.03 × 104 4.46 × 104 1.22 × 105 2.30 × 104 2.02 × 104 1.59 × 104

6.97 × 104 1.04 × 105 1.36 × 105 5.28 × 104 7.01 × 104 4.78 × 104

contrastive study. The test calculation (Table 1) shows that the β0 of Li5−BN-2b is the largest among the four structures, which is independent of the selected functionals. According to the test results and our previous work,17 the CAM-B3LYP is adequate for our purpose, considering computational cost and accuracy. For the basis set, the multiple-split valence basis set is capable of showing the expansion and contraction of valence atom orbitals in the molecular environment and is suitable for calculation of the (hyper)polarizability.59−62 Furthermore, the test calculations for basis set effect are also shown. As listed in Table S1 in the SI, the basis set effects59 on the trend of the β0 are small. For example, the β0 of Li5−BN-1a is larger than that of Li5−BN-2a, which is independent of the selected basis sets. Therefore, the first hyperpolarizability is evaluated at the CAM-B3LYP/6-31G(d) level for discussion together with other electronic properties. The polarizability (α0) is defined as follows 1 α0 = (αxx + αyy + αzz) (1) 3

COMPUTATIONAL DETAILS

For theoretical investigations, selecting a suitable model is important to understand the relationship between the calculated results and physical properties.29,47−50 In this work, the carbon− boron−nitride heterojunction nanotube fragment (5, 0) with a suitable length (9 Å) is chosen as the basic structure (tests for longer CNT fragments are also shown in the Supporting Information, SI). The geometry structures were optimized at the density functional theory (DFT) B3LYP51−53/6-31G(d) level. For the calculation of the (hyper)polarizabilities, some deficiencies of traditional DFT methods (such as B3LYP) might limit them to describe the electronic properties of such large systems.38,54,55 In 2004, a Coulomb-attenuated hybrid exchange-correlation density functional (CAM-B3LYP56,57) was developed to overcome these limitations. It is suitable to predict the molecular NLO properties of similar systems, for example, the fullerene-dimers58 and corresponding BNNT drivatives.17,28 In this work, we have selected a series of DFT methods for a

The static first hyperpolarizability (β0) is noted as β0 = (βx2 + βy2 + βz2)1/2

(2)

where βi =

3 (β + βijj + βikk ), 5 iii

i, j, k = x, y, z

(3)

All of the calculations were performed with the Gaussian 09 program package.63

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RESULTS AND DISCUSSIONS The optimized structures of the four isoelectronic models are exhibited in Figure 1, and the main bond lengths are listed in Table 2. The C−N bond length in connecting area of Li5−BN-1a is close to that of Li5−BN-1b (about 1.37 Å). Similarly, the C−B 14186

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effective strategy than activating the BN-segment for enhancing the β0 of carbon−boron−nitride heterojunction nanotubes by lithiation. We are interested in the origin of the results, and the details are discussed as follows. According to an approximately two-level expression proposed by Oudar,64 the β0 value is proportional to the oscillator strength ( f 0) and the difference of dipole moment between ground state and crucial excited state (Δμ) and inversely proportional to the third power of transition energy (ΔE3). In this work, the ΔE of the four models was estimated by TD-CAM-B3LYP, and the results are listed in Table 3. The ΔE value of Li5−BN-1a/Li5− BN-1b is lower than that of the corresponding Li5−BN-2a/Li5− BN-2b, respectively. It confirms that the N-connecting pattern of the BN-segment linking to the conjugated C-segment decreases the transition energy.17 Therefore, the β0 value of Li5−BN-1b and Li5−BN-2b is not mainly dependent on the ΔE3 in this work. Significantly, the Δμ (12.95 D) of Li5−BN-2b is dramatically larger than that (0.98−4.98 D) of the other three analogues. In this context, the larger Δμ of Li5−BN-2b is the key factor why its β0 value is larger than that of Li5−BN-1b. Furthermore, we focused on analyzing the molecular orbitals of the important transition states of the four multilithium salts to understand the origin of these properties. As shown in Figure 2, for Li5−BN-2a, the transition state orbitals are mainly contributed by the C-segment, while the lithium atoms contribute little. On the other hand, both the ground state orbital and excited state orbital of Li5−BN-1b are contributed by the Csegment and lithium atoms. Therefore, the charge transfer of the two multilithium salts is small so that the corresponding Δμ is small. However, the ground state orbital of Li5−BN-2b is contributed by the C-segment, while the excited state orbital is contributed by the lithium atoms, which is similar to our previous investigation on the CNT multilithium salts. Namely, the charge transfer is from the C-segment to the lithium atoms. Therefore, the large Δμ of Li5−BN-2b originates from its larger charge transfer from the ground state to the crucial transition state. To get insight into the charge transfer properties, we consider Ciofini’s scheme65 to analyze corresponding parameters in detail by the Multiwfn procedure66 (the computational details are shown in SI). According to Table 3, the transferred charge (qCT) of Li5−BN-2b is 0.85, which is significantly larger than that (0.27) of Li5−BN-1b. On the other hand, the distance of charge transfer (DCT) of Li5−BN-2b is 2.92 Å, which is longer than 1.13 Å of Li5−BN-1b. The larger DCT and qCT of Li5−BN-2b are beneficial to the distortion of the electron cloud, which is the essential reason that the Δμ value of Li5−BN-2b is larger. On the other hand, the total density of states (TDOS) and projected

Table 2. Main Bond Lengths (Å) of the Four Isoelectronic Models Optimized at the B3LYP/6-31G(d) Level and the Relative Energy (kcal/mol) Li5−BN-1a C−Li B/N−Li C−H B/N−H B/N−C Li−Li relative energy a

Li5−BN-2a

2.136 1.087

1.891 1.087

1.371 3.138 0a

1.561 2.823 −144.33

Li5−BN-1b

Li5−BN-2b

2.034

1.988

1.189 1.366 2.816 −62.75

1.016 1.539 3.020 −106.68

Relative energy in this line is the energy difference between Li5−BN-1a.

bond length in connecting area of Li5−BN-2a is also close to that of Li5−BN-2b (about 1.56 Å), which indicates the structure of the connecting area is slightly influenced by the different edge environment. It is worthy of note that the maximal difference of Li−Li bond length is 0.32 Å. It shows that the Li−Li bond length might be significantly influenced by the different chemical environment. On the other hand, the maximal difference of relative energy is about 144.33 kcal mol−1, indicating that the electronic structures might be quite different even though the geometrical structure is similar. The electronic properties of the four structures are interesting. As listed in Table 3, the α0 of Li5−BN-1a is 7.05 × 102 au, which is larger than that (5.94 × 102 au) of Li5−BN-2a. It is in line with our previous investigation on the pristine heterojunction nanotubes (BN-1 and BN-2), which shows the N-connecting pattern of the BN-segment linking to the C-segment effectively enhanced the α0 of heterojunction nanotubes.17 Correspondingly, the α0 (1.42 × 103 au) of Li5−BN-1b is also larger than that (6.99 × 102 au) of Li5−BN-2a. However, the variation trend of β0 values of the four multilithium salt compounds is dramatic. Results show that the lithiation effect significantly enhances β0 value. For example, the β0 of Li5−BN-1a (3.22 × 104 au) and Li5−BN-1b (6.03 × 104 au) is larger than that of BN-1 (1.80 × 104 au). It is worthy of note that the difference of β0 between Li5−BN-1b and Li5−BN-2b (6.97 × 104 au) is small, though the β0 of Li5−BN-1a is obviously larger than that (1.42 × 104 au) of Li5−BN-2a. To confirm the results, we consider other functionals to calculate corresponding electronic properties of the four compounds. As shown in Table 1, the β0 of Li5−BN-1b is smaller than that of Li5−BN-2b, which is independent of the calculated methods. It reveals that for the β0 of multilithium salts obtained by activating the C-segment the B-connecting pattern could not be negligible. In this context, activating the C-segment is a more

Table 3. Polarizability α0 (au) and First Hyperpolarizability β0 (au) at the CAM-B3LYP/6-31G(d) Level, the Oscillator Strength f 0, the Transition Energy ΔE (eV), and the Difference of Dipole Moment between the Ground State and Crucial Excited State (Δμ) at the TD-CAM-B3LYP/6-31G(d), Transferred Charge qCT (au), and the Distance of Charge Transfer DCT (Å) BN-1 βx βy βz β0 α0 f0 ΔE Δμ qCT DCT

Li5−BN-1a

BN-2

−1.05 × 10 −7.66 −2.00 1.05 × 104 6.21 × 102 0.25 1.79 1.96 0.46 1.13 4

−3.51 × 10 2.60 × 102 −2.60 × 101 4.37 × 102 5.59 × 102 0.10 2.28 0.83 0.73 0.22 2

−3.22 × 10 −6.64 × 102 −19 3.22 × 104 7.05 × 102 0.20 1.73 4.98 0.56 1.80 4

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Li5−BN-2a

Li5−BN-1b

−1.42 × 10 −2.94 × 102 11 1.42 × 104 5.94 × 102 0.08 2.33 0.98 0.31 0.61

−6.03 × 10 −34 −22 6.03 × 104 1.42 × 103 0.33 0.64 1.42 0.27 1.13

4

Li5−BN-2b 4

6.96 × 104 9.80 × 102 −50 6.97 × 104 6.99 × 102 0.07 1.02 12.95 0.85 2.92

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Figure 2. Crucial transitions and corresponding orbital energy (eV) of Li5−BN-1a, Li5−BN-2a, Li5−BN-1b, and Li5−BN-2b.

Figure 3. Total and partial (the BN segment and C segment) density of states (TDOS and PDOS) around the HOMO−LUMO gap.

Li5−BN-2b is mainly contributed by the five lithium atoms (86.38%), while the HOMO is mainly contributed by C segment

partial density of states (PDOS) have also been analyzed by using the Aomix program.67,68 As plotted in Figure 3, the LUMO of 14188

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(83.03%). Obviously, the charge transfer from the C segment to lithium atoms in Li5−BN-2b is significantly larger that in Li5−BN-1b. On the other hand, the HOMO−4 and LUMO+1 of Li5−BN-2a are almost contributed by the C segment (94.16% and 92.48%), so that the Δμ of Li5−BN-2a is very small (0.98). This qualitatively explains why the Δμ of Li5−BN-2b is larger than that of the other three isoelectronic models. Furthermore, we compared the first hyperpolarizability of Li5−BN-2b to values reported for other lithium-doped systems. The β0 value of Li5−BN-2b is much larger than that of the known electrides (HCN)nLi and Li@calix[4]pyrrole22 (the range of the β0 values is 3.38 × 103−1.57 × 104 au) as well as close to that of the Li−Li5[5]cyclacene44 (3.54 × 104 au). Therfore, the transition nature of carbon−boron−nitride heterojunction nanotubes is significantly dependent on the activating segment of lithiation.

CONCLUSIONS In summary, four isoelectronic models were systematically investigated to explore the lithiation effect on the β0 of the carbon−boron−nitride heterojunction nanotubes with differently connecting patterns. Interestingly, for lithiation on the BN-segment, the β0 (3.22 × 104 au) of Li5−BN-1a is larger than that (1.42 × 104 au) of corresponding Li5−BN-2a, which is in accordance with our previous investigation on pristine heterojunction nanotubes. However, for lithiation on the C-segment, the β0 of Li5−BN-1b is 6.03 × 104 au, which is slightly smaller than that (6.97 × 104 au) of Li5−BN-2b. In this context, activating the C-segment is a more effective strategy than activating the BN-segment for enhancing the β0 of carbon− boron−nitride heterojunction nanotubes by lithiation. Correspondingly, the transferred charge and distance of charge transfer of Li5−BN-2b are obviously larger than those of Li5−BN-1b. As a result, the Δμ (12.95 D) of Li5−BN-2b is significantly larger than that (0.98−4.98 D) of the other three analogues, which originates from the large charge transfer from the C-segment to lithium atoms. Therefore, our studies indicate that the large charge transfer from the C-segment to lithium atoms in Li5−BN-2b induces a large Δμ, which significantly enhances the static first hyperpolarizabilities of heterojunction nanotubes. ASSOCIATED CONTENT

S Supporting Information *

The test for functionals, test for longer CNT segments, and computational details of Ciofini’s scheme. This material is available free of charge via the Internet at http://pubs.acs.org.

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REFERENCES

(1) Ivanovskaya, V. V.; Zobelli, A.; Stéphan, O.; Briddon, P. R.; Colliex, C. BN Domains Included into Carbon Nanotubes: Role of Interface. J. Phys. Chem. C 2009, 113, 16603−16609. (2) Choi, J.; Kim, Y.-H.; Chang, K. J.; Tománek, D. Itinerant Ferromagnetism in Heterostructured C/BN Nanotubes. Phys. Rev. B 2003, 67, 125421. (3) Enouz, S.; Stéphan, O.; Cochon, J.-L.; Colliex, C.; Loiseau, A. C− BN Patterned Single-Walled Nanotubes Synthesized by Laser Vaporization. Nano Lett. 2007, 7, 1856−1862. (4) Du, A.; Chen, Y.; Zhu, Z.; Lu, G.; Smith, S. C. C-BN Single-Walled Nanotubes from Hybrid Connection of BN/C Nanoribbons: Prediction by ab initio Density Functional Calculations. J. Am. Chem. Soc. 2009, 131, 1682−1683. (5) Guo, J. D.; Zhi, C. Y.; Bai, X. D.; Wang, E. G. Boron Carbonitride Nanojunctions. Appl. Phys. Lett. 2002, 80, 124−126. (6) Zhi, C.; Bando, Y.; Tang, C.; Golberg, D. Engineering of Electronic Structure of Boron-Nitride Nanotubes by Covalent Functionalization. Phys. Rev. B 2006, 74, 153413. (7) Zhang, Z.-Y.; Zhang, Z.; Guo, W. Stability and Electronic Properties of a Novel C-BN Heteronanotube from First-Principles Calculations. J. Phys. Chem. C 2009, 113, 13108−13114. (8) Huang, B.; Si, C.; Lee, H.; Zhao, L.; Wu, J.; Gu, B.-L.; Duan, W. Intrinsic Half-Metallic BN-C Nanotubes. Appl. Phys. Lett. 2010, 97, 043115−043113. (9) Machado, M.; Kar, T.; Piquini, P. The Influence of the Stacking Orientation of C and BN Stripes in the Structure, Energetics, and Electronic Properties of BC2N Nanotubes. Nanotechnology 2011, 22, 205706−205706. (10) Wu, M. M.; Zhong, X.; Wang, Q.; Sun, Q.; Pandey, R.; Jena, P. Anisotropy and Transport Properties of Tubular C-BN Janus Nanostructures. J. Phys. Chem. C 2011, 115, 23978−23983. (11) Pruneda, J. M. Native Defects in Hybrid C/BN Nanostructures by Density Functional Theory Calculations. Phys. Rev. B 2012, 85, 045422. (12) EI-Barbary, A. A.; Eid, K. M.; Kamel, M. A.; Hassan, M. M. Band Gap Engineering in Short Heteronanotube Segments via Monovacancy Defects. Comput. Mater. Sci. 2013, 69, 87−94. (13) Esrafili, M.; Behzadi, H. A DFT Study on Carbon-Doping at Different Sites of (8, 0) Boron Nitride Nanotube. Struct. Chem. 2013, 24, 573−581. (14) Iijima, S. Helical Microtubules of Graphitic Carbon. Nature 1991, 354, 56−58. (15) Chopra, N. G.; Luyken, R. J.; Cherrey, K.; Crespi, V. H.; Cohen, M. L.; Louie, S. G.; Zettl, A. Boron Nitride Nanotubes. Science 1995, 269, 966−967. (16) An, W.; Turner, C. H. Linking Carbon and Boron-Nitride Nanotubes: Heterojunction Energetics and Band Gap Tuning. J. Phys. Chem. Lett. 2010, 1, 2269−2273. (17) Zhong, R.-L.; Sun, S.-L.; Xu, H.-L.; Qiu, Y.-Q.; Su, Z.-M. BN Segment Doped Effect on the First Hyperpolarizibility of Heteronanotubes: Focused on an Effective Connecting Pattern. J. Phys. Chem. C 2013, 117, 10039−10044. (18) Zhong, R.-L.; Zhang, J.; Muhammad, S.; Hu, Y.-Y.; Xu, H.-L.; Su, Z.-M. Boron/Nitrogen Substitution of the Central Carbon Atoms of the Biphenalenyl Diradical π Dimer: A Novel 2e−12c Bond and Large NLO Responses. Chem.Eur. J. 2011, 17, 11773−11779. (19) Shen, Y. R. The Principles of Nonlinear Optics; Wiley: NewYork, 1984. (20) Eaton, D. F. Nonlinear Optical Materials. Science 1991, 253, 281− 287. (21) Kanis, D. R.; Ratner, M. A.; Marks, T. J. Design and Construction of Molecular Assemblies with Large Second-Order Optical Nonlinearities. Quantum Chemical Aspects. Chem. Rev. 1994, 94, 195−242. (22) Chen, W.; Li, Z.-R.; Wu, D.; Li, Y.; Sun, C.-C.; Gu, F. L. The Structure and the Large Nonlinear Optical Properties of Li@ calix[4]pyrrole. J. Am. Chem. Soc. 2005, 127, 10977−10981. (23) Coe, B. J. Switchable Nonlinear Optical Metallochromophores with Pyridinium Electron Acceptor Groups. Acc. Chem. Res. 2006, 39, 383−393.

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AUTHOR INFORMATION

Corresponding Authors

*E-mail: [email protected]. *E-mail: [email protected]. Notes

The authors declare no competing financial interest.

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ACKNOWLEDGMENTS The authors gratefully acknowledge financial support from NSFC (21003019 and 21173098), the Science and Technology Development Planning of Jilin Province (20100178, 201201062, and 20140101046JC), The Fundamental Research Funds for the Central Universities (12SSXT131), the Doctoral Fund of Ministry of Education of China (20100043120006), and Computing Center of Jilin Province for essential support, and Dr. Xu acknowledges support from Hong Kong Scholars Program. 14189

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Article

(24) Xu, H.-L.; Li, Z.-R.; Wu, D.; Wang, B.-Q.; Li, Y.; Gu, F. L.; Aoki, Y. Structures and Large NLO Responses of New Electrides: Li-Doped Fluorocarbon Chain. J. Am. Chem. Soc. 2007, 129, 2967−2970. (25) Champagne, B. Polarizabilities and Hyperpolarizabilities. Chem. Modell. 2009, 6, 17−62. (26) Muhammad, S.; Xu, H.; Liao, Y.; Kan, Y.; Su, Z. Quantum Mechanical Design and Structure of the Li@B10H14 Basket with a Remarkably Enhanced Electro-Optical Response. J. Am. Chem. Soc. 2009, 131, 11833−11840. (27) Nakano, M.; Minami, T.; Yoneda, K.; et al. Giant Enhancement of the Second Hyperpolarizabilities of Open-Shell Singlet Polyaromatic Diphenalenyl Diradicaloids by an External Electric Field and Donor− Acceptor Substitution. J. Phys. Chem. Lett. 2011, 2, 1094−1098. (28) Zhong, R.-L.; Xu, H.-L.; Muhammad, S.; Zhang, J.; Su, Z.-M. The Stability and Nonlinear Optical Properties: Encapsulation of an Excess Electron Compound LiCNLi within Boron Nitride Nanotubes. J. Mater. Chem. 2012, 22, 2196−2202. (29) Zhong, R.-L.; Xu, H.-L.; Sun, S.-L.; Qiu, Y.-Q.; Su, Z.-M. The Excess Electron in a Boron Nitride Nanotube: Pyramidal NBO Charge Distribution and Remarkable First Hyperpolarizability. Chem.Eur. J. 2012, 18, 11350−11355. (30) Muhammad, S.; Xu, H.; Su, Z. Capturing a Synergistic Effect of a Conical Push and an Inward Pull in Fluoro Derivatives of Li@B10H14 Basket: Toward a Higher Vertical Ionization Potential and Nonlinear Optical Response. J. Phys. Chem. A 2011, 115, 923−931. (31) Muhammad, S.; Minami, T.; Fukui, H.; Yoneda, K.; Kishi, R.; Shigeta, Y.; Nakano, M. Halide Ion Complexes of Decaborane (B10H14) and Their Derivatives: Noncovalent Charge Transfer Effect on Second-Order Nonlinear Optical Properties. J. Phys. Chem. A 2011, 116, 1417−1424. (32) Muhammad, S.; Xu, H.-L.; Zhong, R.-L.; Su, Z.-M.; Al-Sehemi, A. G.; Irfan, A. Quantum Chemical Design of Nonlinear Optical Materials by Sp2-Hybridized Carbon Nanomaterials: Issues and Opportunities. J. Mater. Chem. C 2013, 1, 5439−5449. (33) Muhammad, S.; Fukuda, K.; Minami, T.; Kishi, R.; Shigeta, Y.; Nakano, M. Interplay between the Diradical Character and Third-Order Nonlinear Optical Properties in Fullerene Systems. Chem.Eur. J. 2013, 19, 1677−1685. (34) Muhammad, S.; Minami, T.; Fukui, H.; Yoneda, K.; Minamide, S.; Kishi, R.; Shigeta, Y.; Nakano, M. Comparative Study of Diradical Characters and Third-Order Nonlinear Optical Properties of Linear/ Cyclic Acenes Versus Phenylenes. Int. J. Quantum Chem. 2013, 113, 592−598. (35) Xiao, D.; Bulat, F. A.; Yang, W.; Beratan, D. N. A Donor− Nanotube Paradigm for Nonlinear Optical Materials. Nano Lett. 2008, 8, 2814−2818. (36) Ma, F.; Zhou, Z.-J.; Li, Z.-R.; Wu, D.; Li, Y.; Li, Z.-S. Lithium Salt of End-Substituted Nanotube: Structure and Large Nonlinear Optical Property. Chem. Phys. Lett. 2010, 488, 182−186. (37) Wang, Y.-F.; Li, Z.; Li, Y.; Li, Z.-R.; Li, Z.-J.; Wu, D.; Ma, F.; Sun, C.-C. Mobius Basket Molecule: Structure and Properties. Phys. Chem. Chem. Phys. 2010, 12, 8847−8855. (38) Champagne, B.; Perpète, E. A.; Jacquemin, D.; van Gisbergen, S. J. A.; Baerends, E.-J.; Soubra-Ghaoui, C.; Robins, K. A.; Kirtman, B. Assessment of Conventional Density Functional Schemes for Computing the Dipole Moment and (Hyper)polarizabilities of Push− Pull π-Conjugated Systems. J. Phys. Chem. A 2000, 104, 4755−4763. (39) Zhong, R.-L.; Xu, H.-L.; Su, Z.-M.; Li, Z.-R.; Sun, S.-L.; Qiu, Y.-Q. Spiral Intramolecular Charge Transfer and Large First Hyperpolarizability in Möbius Cyclacenes: New Insight into the Localized π Electrons. ChemPhysChem 2012, 2349−2353. (40) Champagne, B.; Botek, E.; Nakano, M.; Nitta, T.; Yamaguchi, K. Basis Set and Electron Correlation Effects on the Polarizability and Second Hyperpolarizability of Model Open-Shell Pi-Conjugated Systems. J. Chem. Phys. 2005, 122, 114315. (41) Coe, B. J. Developing Iron and Ruthenium Complexes for Potential Nonlinear Optical Applications. Coord. Chem. Rev. 2013, 257, 1438−1458.

(42) Coe, B. J.; Foxon, S. P.; Helliwell, M.; et al. Heptametallic, Octupolar Nonlinear Optical Chromophores with Six Ferrocenyl Substituents. Chem.Eur. J. 2013, 19, 6613−6629. (43) Zhang, C.-C.; Xu, H.-L.; Hu, Y.-Y.; Sun, S.-L.; Su, Z.-M. Quantum Chemical Research on Structures, Linear and Nonlinear Optical Properties of the Li@n-Acenes Salt (n = 1, 2, 3, and 4). J. Phys. Chem. A 2011, 115, 2035−2040. (44) Xu, H.-L.; Zhong, R.-L.; Sun, S.-L.; Su, Z.-M. Widening or Lengthening? Enhancing the First Hyperpolarizability of Tubiform Multilithium Salts. J. Phys. Chem. C 2011, 115, 16340−16346. (45) Golberg, D.; Bando, Y.; Tang, C. C.; Zhi, C. Y. Boron Nitride Nanotubes. Adv. Mater. 2007, 19, 2413−2432. (46) Golberg, D.; Bando, Y.; Huang, Y.; Terao, T.; Mitome, M.; Tang, C.; Zhi, C. Boron Nitride Nanotubes and Nanosheets. ACS Nano 2010, 4, 2979−2993. (47) Maroulis, G. In Applications of Density Functional Theory to Chemical Reactivity; Putz, M. V., Mingos, D. M. P., Eds.; Structure and Bonding; Springer: Berlin Heidelberg, 2012; Vol. 149, pp 95−129. (48) Morita, Y.; Suzuki, S.; Sato, K.; Takui, T. Synthetic Organic Spin Chemistry for Structurally Well-Defined Open-Shell Graphene Fragments. Nat. Chem. 2011, 3, 197−204. (49) Pyykkö, P. The Physics behind Chemistry and the Periodic Table. Chem. Rev. 2011, 112, 371−384. (50) Maroulis, G. Evaluating the Performance of Correlated Methods in Molecular Property Calculations: Pattern Recognition and Clustering in Spaces of Theoretical Descriptions. Int. J. Quantum Chem. 1995, 55, 173−180. (51) Becke, A. D. Density-Functional Thermochemistry. III. The Role of Exact Exchange. J. Chem. Phys. 1993, 98, 5648−5652. (52) Becke, A. D. A New Mixing of Hartree–Fock and Local DensityFunctional Theories. J. Chem. Phys. 1993, 98, 1372−1377. (53) Stephens, P. J.; Devlin, F. J.; Chabalowski, C. F.; Frisch, M. J. Ab Initio Calculation of Vibrational Absorption and Circular Dichroism Spectra Using Density Functional Force Fields. J. Phys. Chem. 1994, 98, 11623−11627. (54) Zhao, Y.; Truhlar, D. G. Density Functionals with Broad Applicability in Chemistry. Acc. Chem. Res. 2008, 41, 157−167. (55) Waller, M. P.; Kruse, H.; Muck-Lichtenfeld, C.; Grimme, S. Investigating Inclusion Complexes using Quantum Chemical Methods. Chem. Soc. Rev. 2012, 41, 3119−3128. (56) Iikura, H.; Tsuneda, T.; Yanai, T.; Hirao, K. A Long-Range Correction Scheme for Generalized-Gradient-Approximation Exchange Functionals. J. Chem. Phys. 2001, 115, 3540−3544. (57) Yanai, T.; Tew, D. P.; Handy, N. C. A New Hybrid Exchange− Correlation Functional using the Coulomb-Attenuating Method (CAM-B3LYP). Chem. Phys. Lett. 2004, 393, 51−57. (58) Ma, F.; Li, Z.-R.; Zhou, Z.-J.; Wu, D.; Li, Y.; Wang, Y.-F.; Li, Z.-S. Modulated Nonlinear Optical Responses and Charge Transfer Transition in Endohedral Fullerene Dimers Na@C60C60@F with nFold Covalent Bond (n = 1, 2, 5, and 6) and Long Range Ion Bond. J. Phys. Chem. C 2010, 114, 11242−11247. (59) Maroulis, G. Static Hyperpolarizability of the Water Dimer and the Interaction Hyperpolarizability of Two Water Molecules. J. Chem. Phys. 2000, 113, 1813−1820. (60) Maroulis, G. How Large is the Static Electric (Hyper)polarizability Anisotropy in HXeI? J. Chem. Phys. 2008, 129, 044314. (61) Maroulis, G. Electric Multipole Moments, Polarizability, and Hyperpolarizability of Xenon Dihydride (HXeH). Theor. Chem. Acc. 2011, 129, 437−445. (62) Maroulis, G.; Xenides, D.; Hohm, U.; Loose, A. Dipole, Dipole− Quadrupole, and Dipole−Octopole Polarizability of Adamantane, C10H16, From Refractive Index Measurements, Depolarized Collision-Induced Light Ccattering, Conventional Ab Initio and Density Functional Theory Calculations. J. Chem. Phys. 2001, 115, 7957−7967. (63) Frisch, M. J.; Trucks, G. W.; Schlegel, H. B. et al., Gaussian 09, revision A.02; Gaussian, Inc.: Wallingford, CT, 2009. (64) Oudar, J. L.; Chemla, D. S. Hyperpolarizabilities of the Nitroanilines and Their Relations to the Excited State Dipole Moment. J. Chem. Phys. 1977, 66, 2664−2668. 14190

dx.doi.org/10.1021/jp503281q | J. Phys. Chem. C 2014, 118, 14185−14191

The Journal of Physical Chemistry C

Article

(65) Le Bahers, T.; Adamo, C.; Ciofini, I. A Qualitative Index of Spatial Extent in Charge-Transfer Excitations. J. Chem. Theory Comput. 2011, 7, 2498−2506. (66) Lu, T.; Chen, F. Multiwfn: A Multifunctional Wavefunction Analyzer. J. Comput. Chem. 2012, 33, 580−592. (67) Gorelsky, S. I.; Lever, A. B. P. Electronic Structure and Spectra of Ruthenium Diimine Complexes by Density Functional Theory and INDO/S. Comparison of the Two Methods. J. Organomet. Chem. 2001, 635, 187−196. (68) Gorelsky, S. I. AOMix: Program for Molecular Orbital Analysis; University of Ottawa: Ontario, 2009.

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