Communication Cite This: J. Am. Chem. Soc. 2018, 140, 1592−1595
pubs.acs.org/JACS
Non-Centrosymmetric RbNaMgP2O7 with Unprecedented ThermoInduced Enhancement of Second Harmonic Generation Sangen Zhao,† Xiaoyan Yang,‡ Yi Yang,§ Xiaojun Kuang,*,‡ Fengqi Lu,‡ Pai Shan,† Zhihua Sun,† Zheshuai Lin,*,§ Maochun Hong,† and Junhua Luo*,† †
State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002, China ‡ Guangxi Ministry-Province Jointly-Constructed Cultivation Base for State Key Laboratory of Processing for Nonferrous Metal and Featured Materials, Guangxi Universities Key Laboratory of Non-ferrous Metal Oxide Electronic Functional Materials and Devices, College of Materials Science and Engineering, Guilin University of Technology, Guilin 541004, China § Beijing Center for Crystal R&D, Key Lab of Functional Crystals and Laser Technology of Chinese Academy of Sciences, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, China S Supporting Information *
(BO3)3,3c Pb2BO3Cl,4d CsPbCO3F,4e BiFSeO3,4f as well as BaHgSe25a and LiAsS2.5b Unfortunately, the aforementioned strategy is prone to cause the optical transparency window of the resultant materials evidently narrow. For instance, as compared with the structural analogues ABCO3F (A = K, Rb, Cs; B = Ca, Sr, Ba),7 CsPbCO3F4e exhibits an enhanced SHG response owing to the introduction of stereoactive lone-pair Pb2+, but its optical absorption edge (∼300 nm) is markedly red-shift as compared with those of ABCO3F (below 200 nm, located at deep-UV region). On the other hand, deep-UV NLO materials play a unique and crucial role in a number of unprecedented scientific instruments;8 The wavelengths in deep-UV region almost approach the theoretical transparency limit of NLO materials.9 Therefore, it remains urgent but challenging to develop new strategies to enhance the SHG responses of deep-UV NLO materials. In recent years, scientists put forth a variety of new strategies to chemically design and synthesize SHG-enhanced deep-UV NLO materials,10 such as inducing F-directed polar displacements11 or new π-conjugated groups,7,12 combing borate and phosphate/silicate anionic groups,13 constructing compact layered structures,14 aligning nonbonding O-2p orbitals,15 as well as condensing P−O groups.16 On the other hand, researchers have put forth a series of physical processing routes, such as poling using thermal, optical and electron beam irradiation, to induce/enhance SHG responses in glassy fibers since 1981.17 Nevertheless, there are still lack of physical strategies on how to induce SHG enhancement in NLO crystalline materials. Herein, we report a new NCS crystal RbNaMgP2O7 (Ι), which is deep-UV transparent and exhibits evident SHG enhancement under physical stimuli of heat. This work highlights thermo-induced phase transition as an effective routine to enhance SHG response of a deep-UV NLO crystal. Phase pure Ι powders were synthesized by high-temperature solid-state reaction techniques with raw reagents in the stoichiometric molar ratio. Single crystals of Ι were grown by
ABSTRACT: It is of great difficulty to obtain deep-UV transparent materials with enhanced second harmonic generation (SHG), mainly limited by the theoretically poor transparency of these materials in the deep-UV spectral region. Here we report a new noncentrosymmetric, deep-UV transparent phosphate RbNaMgP2O7, which undergoes a thermo-induced reversible phase transition (at a high temperature of 723 K) and correspondingly an evident SHG enhancement up to ∼1.5 times. The phase transition is aroused by the twist of [P2O7]4− dimers with deviation from the P−O−P equilibrium positions. Theoretical analyses reveal that the enhanced SHG can be ascribed to the thermo-induced collective alignment of SHG-active [P2O7]4− dimers along the polar axis of high-temperature phase. This work provides an unprecedented physical routine (to SHGenhanced materials) that is distinguished from the traditional one by chemical design and synthesis.
N
onlinear optical (NLO) materials can efficiently expand the fixed (or limited) wavelengths of laser sources to much wider spectral regions, thereby playing a significant role in modern laser science and technology.1 The prerequisite of a NLO crystal is that it should be crystallographically noncentrosymmetric (NCS), but NCS alone is inadequate for practical NLO applications. From the viewpoint of optics, the crystal should also have a wide optical transparency window, a large second harmonic generation (SHG) response, and phasematching capability.1 Over the past decades, great efforts have been made on chemical design and synthesis of NLO materials with enhanced SHG responses.2 A widely used and effective strategy is to introduce/combine various NLO-active structural units,3 which include second-order Jahn−Teller distorted octahedra of d0 cation centers or stereoactive lone-pair cations,4 polar chalcogenide units,5 as well as d10 cation centered polyhedra with large polar displacement.6 A number of strongly SHG-active materials were thus discovered, such as BaTeMo2O9,3a Pb2B5O9I,3b NaI3O8,4c Pb2Ba3(BO3)3Cl,4a Cd4BiO© 2018 American Chemical Society
Received: November 27, 2017 Published: January 18, 2018 1592
DOI: 10.1021/jacs.7b12518 J. Am. Chem. Soc. 2018, 140, 1592−1595
Communication
Journal of the American Chemical Society the top-seeded solution growth method using Rb2O−P2O5 flux. The as-grown Ι crystal is shown in Figure S1 in the Supporting Information. As shown in Figure 1a, the differential scanning
Figure 1. DSC and thermogravimetric curves for Ι measured (a) from 500 to 1123 K and (b) from 600 to 800 K. The green dashed box in panel a indicates where the DSC peaks appear.
calorimetric (DSC) curves indicate that Ι is a congruently melting compound with a melting point around 1059 K. Interestingly, a tiny peak at 714 K appears in the heating curve and another tiny peak appears at 711 K in the cooling curve (Figure 1b). In addition, there is no evident weight loss during the process of DSC measurement according to the thermogravimetric analysis. These results imply that Ι is likely to undergo a reversible thermo-induced phase transition at the vicinity of Tc = 714 K. The thermal hysteresis of about 3 K between the two peaks indicates that the phase transition of I is discontinuous. We also carried out additional cycles of DSC analyses. It was found that the DSC curves are reproducible, demonstrating that the phase transition of I is reversible. For convenience, we denote the phase above/below Tc as hightemperature phase (HTP)/low-temperature phase (LTP). To further verify the phase transition of I, we determined the crystal structure of LTP by single-crystal XRD analysis at room temperature, and then performed variable-temperature powder XRD analyses from room temperature to 873 K. Subsequently, the XRD data were analyzed by the Rietveld method18 and the crystal structure of HTP was deduced based on the room temperature cell. The calculated and experimental XRD patterns match each other very well for LTP (see Figure S2). Profile fit to the powder XRD pattern of HTP is shown in Figure S3. Figure S4 displays the selected variable-temperature XRD patterns for I powders obtained by crashing the single crystals of I. Figure S5 shows the variable-temperature cell parameters. Both Figures S4 and S5 are consistent with the phase transition of I. Detailed crystallographic information is listed in Tables S1−S4. Both the LTP and HTP of Ι are NCS and polar. They crystallize in space groups of Pna21 (No. 33) and Ccm21 (No. 36), respectively. Both structures exhibit very close lattice parameters and HTP can be considered as a slight deformation from LTP. They feature layered structures composed of undulating [MgP2O7]∞ sheets stacking along the a axis (Figure 2a,b). Rb+ and Na+ cations reside in the gaps of [MgP2O7]∞ sheets to maintain charge balance. In the [MgP2O7]∞ sheets, each MgO5 polyhedron is linked to two neighboring [P2O7]4− dimers via edge-sharing and another [P2O7]4− dimer via cornersharing, and further extends to a alveolate structure in a [3, 3] connection mode (see Figure 2c,d). The O−P−O angles and P−O distances (Table S3) for LTP and HTP of Ι are normal as compared with those in other phosphates.8b,c,15,16 The crystal structures of LTP and HTP are compared to disclose the microscopic structural origin of phase transition. In the LTP, [P2O7]4− dimers adopt a slightly twisted con-
Figure 2. Variable-temperature crystal structures of Ι. (a) LTP structure. (b) HTP structure. (c) [MgP2O7]∞ sheet of LTP. (d) [MgP2O7]∞ sheet of HTP. (e) [P2O7]4− dimer of LTP. (f) [P2O7]4− dimer of HTP. [MgP2O7]∞ sheets (in dashed red border) are stacked along the a axis in panels a and b. Green polyhedra represent MgO5 polyhedra in panels c and d. The dashed green lines indicate the position of P−O−P plane in panels e and f.
formation with torsion angles of O5−P2−O1−P1 = 8.202(232)° and P2−O1−P1−O3 = 8.609 (217)° (Figure 2e). The O5 and O3 atoms obviously deviate from the P2− O1−P1 plane with distances of 0.2045 and 0.2181 Å, respectively. In comparison, the torsion angles of O4−P2− O1−P1 and P2−O1−P1−O3 in HTP are zero, as there is a mirror symmetric plane inside the [P2O7]4− dimer of HTP (Figure 2f). The twist of [P2O7]4− dimers in LTP should be originating from thermal vibrations of the chain-like skeleton around the P−O−P equilibrium positions. When temperature decreases below Tc, thermal vibrations of skeleton are restricted, and thereby showing deviation from the P−O−P equilibrium positions. Therefore, the lowering symmetry from HTP to LTP is aroused by the thermo-induced twist of [P2O7]4− dimers from the P−O−P equilibrium positions, despite that the twist is so small that it has almost negligible influence on the cell parameters. Optical transmittance spectrum was collected at room temperature on a Lambda 900 UV/vis/NIR Spectrometer from 180 to 400 nm. A transparent I crystal with a thickness of about 1 mm was used for the measurement without polishing. As shown in Figure 3a, I has a deep-UV absorption edge at 185 nm (corresponding to a wide bandgap of 6.70 eV), which is comparable to those of other notable NLO phosphates, such as Ba3P3O10Cl (180 nm),8b RbBa2(PO3)5 (164 nm),16 and Ba5P6O20 (167 nm).8c This deep-UV transparency indicates that I may find applications in the deep-UV spectral region. Because both the LTP and HTP are NCS, they are expected to be NLO-active. First, we carried out powder SHG tests by the Kurtz−Perry method19 with a Q-switched Nd:YAGlaser of λ = 1064 nm at room temperature and 750 K. Polycrystalline 1593
DOI: 10.1021/jacs.7b12518 J. Am. Chem. Soc. 2018, 140, 1592−1595
Communication
Journal of the American Chemical Society
density of states and partial density of states projected on the constitutional atoms. It can be deduced that for both LTP and HTP of I the P−O groups (namely, [P2O7]4− dimers) make the dominant contributions to the SHG coefficients, whereas the contributions of the cations (Rb+, Na+ and Mg2+) are negligibly small. In order to better understand the structural mechanism of SHG enhancement, we further calculated the dipole moments in the unit cell of LTP and HTP with a simple bond-valence approach proposed by Poeppelmeier et al.26 According to the above-mentioned calculations, [P2O7]4− dimers are the dominant NLO-active anionic groups for I, so only their dipole moments are quantified. Detailed calculation results are given in the Supporting Information. Vector summation over the [P2O7]4− geometry gave a dipole moment of 3.43 D for HTP, whereas it gave a half smaller value (1.75 D) for LTP. Meanwhile, owing to the same mm2 point group for both HTP and LTP, the dipole moments of [P2O7]4− dimers cancel out themselves to zero along the a and b axes in the unit cell, whereas they are collective along the polar c axis in the unit cell. As a result, the overall polarity in the unit cell depends directly on the vector (of [P2O7]4− dimers) along the c axis. The more collective alignment of [P2O7]4− dimers in HTP gives rise to a net dipole moment of 11.08 D, which is significantly larger than that of LTP (2.16 D). According to the anionic group theory, the overall NLO response of a crystal is the geometrical superposition of microscopic second-order susceptibility of NLO-active anionic groups.27 It can be rationalized that the SHG enhancement from LTP to HTP is ascribed to the more collective alignment of [P2O7]4− dimers along the polar axis. Notably, this superior alignment is physically induced by heat, which is distinct from the traditional routine to SHG-enhanced materials, namely, chemical design and synthesis. In summary, a new NCS, deep-UV transparent phosphate RbNaMgP2O7 is synthesized. It undergoes a phase transition at a high temperature of 723 K, and correspondingly its SHG response becomes 1.5 times larger. This thermo-induced SHG enhancement can be attributable to a more collective alignment (of NLO-active [P2O7]4− dimers) in the unit cell of HTP. These findings highlight the thermo-induced phase transition as an unprecedented physical routine (to SHG-enhanced materials) distinct from the traditional chemical design and synthesis.
Figure 3. Optical properties of Ι. (a) Transmittance spectrum. (b) Variable-temperature SHG intensities.
KDP samples were used as the references. As shown in Figure S6, the SHG intensities as a function of particle sizes indicate that I is a phase-matchable NLO material at both room temperature and high temperature. The SHG intensities are about 0.9 and 1.4 times that of the KDP reference in the particle size range of 200−250 μm for RTP and HTP, respectively. Such SHG responses are moderate as compared with the other phosphates with [P2O7]4− dimers, including Rb2Ba3(P2O7)2 (0.3 × KDP),16 Cs2Ba3(P2O7)2 (weak),20 LiK3P2O7 (0.2 × KDP),21 LiNa3P2O7 (0.25 × KDP),21 K4Mg4(P2O7)3 (1.3 × KDP) and Rb4Mg4(P2O7)3 (1.4 × KDP),22 as well as CsLiCdP2O7 (1.5 × KDP).23 Subsequently, we measured the SHG signals on polycrystalline I at various temperatures. Interestingly, the SHG intensities jump evidently around Tc with the temperature increasing. There are a variety of compounds with NLO anomaly around the phase transition point and their structural symmetry always increases with the increasing temperature.24 Nevertheless, the symmetry of HTPs is usually so high that it is centrosymmetric or nonpolar. As a result, the HTPs are generally NLO-inert or of low NLOactivity. In this work, I undergoes transition from a polar NCS phase to another polar NCS phase that has a higher symmetry, accompanied by an evident SHG enhancement. To the best of our knowledge, I is the first deep-UV NLO material that undergoes thermo-induced SHG enhancement. In order to disclose the structure−property relationship for the thermo-induced SHG enhancement of I, we performed the first-principles calculations by the plane-wave pseudopotential method implemented in the CASTEP package.25 Figure S7 displays the electronic band structures, which indicate that both the LTP and HTP of I are direct-gap. Figure 4 shows the
■
ASSOCIATED CONTENT
* Supporting Information S
The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/jacs.7b12518. As-grown RbNaMgP2O7 crystal, XRD patterns, electronic band structures, and additional data. Deposition number CCDC 1436550 and 1587766 for LTP and HTP of RbNaMgP2O7, respectively (PDF) Crystallographic data for LTP RbNaMgP2O7 (CIF) Crystallographic data for HTP RbNaMgP2O7 (CIF)
■
AUTHOR INFORMATION
Corresponding Authors
*
[email protected] *
[email protected] *
[email protected] ORCID
Sangen Zhao: 0000-0002-1190-684X
Figure 4. Density of states of (a) LTP and (b) HTP. 1594
DOI: 10.1021/jacs.7b12518 J. Am. Chem. Soc. 2018, 140, 1592−1595
Communication
Journal of the American Chemical Society
Wang, Y.; Zhang, B. B.; Zhang, F. F.; Yang, Z. H.; Pan, S. L. Angew. Chem., Int. Ed. 2017, 56, 14119. (12) Tran, T. T.; Young, J. S.; Rondinelli, J. M.; Halasyamani, P. S. J. Am. Chem. Soc. 2017, 139, 1285. (13) (a) Yu, H.; Zhang, W.; Young, J.; Rondinelli, J. M.; Halasyamani, P. S. Adv. Mater. 2015, 27, 7380. (b) Wu, H. P.; Yu, H. W.; Pan, S. L.; Huang, Z. J.; Yang, Z. H.; Su, X.; Poeppelmeier, K. R. Angew. Chem., Int. Ed. 2013, 52, 3406. (14) (a) Wang, S. C.; Ye, N. J. Am. Chem. Soc. 2011, 133, 11458. (b) Huang, H. W.; Liu, L. J.; Jin, S. F.; Yao, W. J.; Zhang, Y. H.; Chen, C. T. J. Am. Chem. Soc. 2013, 135, 18319. (c) Zhao, S.; Gong, P.; Bai, L.; Xu, X.; Zhang, S.; Sun, Z.; Lin, Z.; Hong, M.; Chen, C.; Luo, J. Nat. Commun. 2014, 5, 4019. (d) Zhao, S. G.; Gong, P. F.; Luo, S. Y.; Liu, S. J.; Li, L. N.; Asghar, M. A.; Khan, T.; Hong, M. C.; Lin, Z. S.; Luo, J. H. J. Am. Chem. Soc. 2015, 137, 2207. (e) Zhao, S.; Kang, L.; Shen, Y.; Wang, X.; Asghar, M. A.; Lin, Z.; Xu, Y.; Zeng, S.; Hong, M.; Luo, J. J. Am. Chem. Soc. 2016, 138, 2961. (f) Tran, T. T.; Koocher, N. Z.; Rondinelli, J. M.; Halasyamani, P. S. Angew. Chem., Int. Ed. 2017, 56, 2969. (15) Li, L.; Wang, Y.; Lei, B. H.; Han, S. J.; Yang, Z. H.; Poeppelmeier, K. R.; Pan, S. L. J. Am. Chem. Soc. 2016, 138, 9101. (16) Zhao, S. G.; Gong, P. F.; Luo, S. Y.; Bai, L.; Lin, Z. S.; Ji, C. M.; Chen, T. L.; Hong, M. C.; Luo, J. H. J. Am. Chem. Soc. 2014, 136, 8560. (17) (a) Sasaki, Y.; Ohmori, Y. Appl. Phys. Lett. 1981, 39, 466. (b) Margulis, W.; Laurell, F.; Lesche, B. Nature 1995, 378, 699. (18) Rietveld, H. M. J. Appl. Crystallogr. 1969, 2, 65. (19) Kurtz, S. K.; Perry, T. T. J. Appl. Phys. 1968, 39, 3798. (20) Li, L.; Han, S. J.; Lei, B. H.; Wang, Y.; Li, H. Y.; Yang, Z. H.; Pan, S. L. Dalton Trans. 2016, 45, 3936. (21) Shi, Y. J.; Wang, Y.; Pan, S. L.; Yang, Z. H.; Dong, X. Y.; Wu, H. P.; Zhang, M.; Cao, J.; Zhou, Z. X. J. Solid State Chem. 2013, 197, 128. (22) Yu, H. W.; Young, J.; Wu, H. P.; Zhang, W. G.; Rondinelli, J. M.; Halasyamani, P. S. Chem. Mater. 2017, 29, 1845. (23) Shen, Y. G.; Zhao, S. G.; Zhao, B. Q.; Ji, C. M.; Li, L. N.; Sun, Z. H.; Hong, M. C.; Luo, J. H. Inorg. Chem. 2016, 55, 11626. (24) (a) Zhang, Y.; Ye, H. Y.; Cai, H. L.; Fu, D. W.; Ye, Q.; Zhang, W.; Zhou, Q. H.; Wang, J. L.; Yuan, G. L.; Xiong, R. G. Adv. Mater. 2014, 26, 4515. (b) Xu, W. J.; He, C. T.; Ji, C. M.; Chen, S. L.; Huang, R. K.; Lin, R. B.; Xue, W.; Luo, J. H.; Zhang, W. X.; Chen, X. M. Adv. Mater. 2016, 28, 5886. (25) (a) Payne, M. C.; Teter, M. P.; Allan, D. C.; Arias, T. A.; Joannopoulos, J. D. Rev. Mod. Phys. 1992, 64, 1045. (b) Clark, S. J.; Segall, M. D.; Pickard, C. J.; Hasnip, P. J.; Probert, M. J.; Refson, K.; Payne, M. C. Z. Kristallogr. - Cryst. Mater. 2005, 220, 576. (26) Maggard, P. A.; Nault, T. S.; Stern, C. L.; Poeppelmeier, K. R. J. Solid State Chem. 2003, 175, 27. (27) Chen, C. T. Sci. Sin. 1979, 22, 756.
Xiaojun Kuang: 0000-0003-2975-9355 Zheshuai Lin: 0000-0002-9829-9893 Junhua Luo: 0000-0002-7673-7979 Notes
The authors declare no competing financial interest.
■
ACKNOWLEDGMENTS This work was supported by the NSFC (21525104, 21571178, 21622101, 51502288, 91622118, 21601188), the Strategic Priority Research Program of Chinese Academy of Sciences (XDB20000000), and the 863 Program of China (2015AA034203). S.Z. is grateful for the support from NSF for Distinguished Young Scholars of Fujian Province (2016J06012) and Youth Innovation Promotion of CAS (2016274).
■
REFERENCES
(1) Becker, P. Adv. Mater. 1998, 10, 979. (2) (a) Wu, L.; Patankar, S.; Morimoto, T.; Nair, N. L.; Thewalt, E.; Little, A.; Analytis, J. G.; Moore, J. E.; Orenstein, J. Nat. Phys. 2017, 13, 350. (b) Zhang, G.; Li, Y. J.; Jiang, K.; Zeng, H. Y.; Liu, T.; Chen, X. G.; Qin, J. G.; Lin, Z. S.; Fu, P. Z.; Wu, Y. C.; Chen, C. T. J. Am. Chem. Soc. 2012, 134, 14818. (c) Liu, H.; Wu, Q.; Jiang, X.; Lin, Z.; Meng, X.; Chen, X.; Qin, J. Angew. Chem., Int. Ed. 2017, 56, 9492. (d) Reshak, A. H.; Auluck, S.; Kityk, I. V. J. Solid State Chem. 2008, 181, 789. (3) (a) Ra, H. S.; Ok, K. M.; Halasyamani, P. S. J. Am. Chem. Soc. 2003, 125, 7764. (b) Huang, Y. Z.; Wu, L. M.; Wu, X. T.; Li, L. H.; Chen, L.; Zhang, Y. F. J. Am. Chem. Soc. 2010, 132, 12788. (c) Zhang, W. L.; Cheng, W. D.; Zhang, H.; Geng, L.; Lin, C. S.; He, Z. Z. J. Am. Chem. Soc. 2010, 132, 1508. (d) Zhao, S. G.; Yang, Y.; Shen, Y. G.; Zhao, B. Q.; Li, L.; Ji, C. M.; Wu, Z. Y.; Yuan, D. Q.; Lin, Z. S.; Hong, M. C.; Luo, J. H. Angew. Chem., Int. Ed. 2017, 56, 540. (4) (a) Dong, X. Y.; Jing, Q.; Shi, Y.; Yang, Z.; Pan, S.; Poeppelmeier, K. R.; Young, J.; Rondinelli, J. M. J. Am. Chem. Soc. 2015, 137, 9417. (b) Sykora, R. E.; Ok, K. M.; Halasyamani, P. S.; Albrecht-Schmitt, T. E. J. Am. Chem. Soc. 2002, 124, 1951. (c) Phanon, D.; Gautier-Luneau, I. Angew. Chem., Int. Ed. 2007, 46, 8488. (d) Zou, G.; Lin, C. S.; Jo, H.; Nam, G.; You, T. S.; Ok, K. M. Angew. Chem., Int. Ed. 2016, 55, 12078. (e) Zou, G. H.; Huang, L.; Ye, N.; Lin, C. S.; Cheng, W. D.; Huang, H. J. Am. Chem. Soc. 2013, 135, 18560. (f) Liang, M. L.; Hu, C. L.; Kong, F.; Mao, J. G. J. Am. Chem. Soc. 2016, 138, 9433. (5) (a) Li, C.; Yin, W.; Gong, P.; Li, X.; Zhou, M.; Mar, A.; Lin, Z.; Yao, J.; Wu, Y.; Chen, C. J. Am. Chem. Soc. 2016, 138, 6135. (b) Bera, T. K.; Jang, J. I.; Song, J. H.; Malliakas, C. D.; Freeman, A. J.; Ketterson, J. B.; Kanatzidis, M. G. J. Am. Chem. Soc. 2010, 132, 3484. (6) Inaguma, Y.; Yoshida, M.; Katsumata, T. J. Am. Chem. Soc. 2008, 130, 6704. (7) Zou, G.; Ye, N.; Huang, L.; Lin, X. J. Am. Chem. Soc. 2011, 133, 20001. (8) (a) Chen, C. T.; Wang, Y. B.; Wu, B. C.; Wu, K. C.; Zeng, W. L.; Yu, L. H. Nature 1995, 373, 322. (b) Yu, P.; Wu, L. M.; Zhou, L. J.; Chen, L. J. Am. Chem. Soc. 2014, 136, 480. (c) Zhao, S. G.; Gong, P. F.; Luo, S. Y.; Bai, L.; Lin, Z. S.; Tang, Y. Y.; Zhou, Y. L.; Hong, M. C.; Luo, J. H. Angew. Chem., Int. Ed. 2015, 54, 4217. (9) Yao, W. J.; He, R.; Wang, X. Y.; Lin, Z. S.; Chen, C. T. Adv. Opt. Mater. 2014, 2, 411. (10) (a) Tran, T. T.; Yu, H. W.; Rondinelli, J. M.; Poeppelmeier, K. R.; Halasyamani, P. S. Chem. Mater. 2016, 28, 5238. (b) Huang, H.; Yao, J.; Lin, Z.; Wang, X.; He, R.; Yao, W.; Zhai, N.; Chen, C. Angew. Chem., Int. Ed. 2011, 50, 9141. (11) (a) Wu, H. P.; Yu, H. W.; Yang, Z. H.; Hou, X. L.; Su, X.; Pan, S. L.; Poeppelmeier, K. R.; Rondinelli, J. M. J. Am. Chem. Soc. 2013, 135, 4215. (b) Shi, G. Q.; Wang, Y.; Zhan, F. F.; Zhang, B. B.; Yang, R. H.; Hou, X. L.; Pan, S. L.; Poeppelmeier, K. R. J. Am. Chem. Soc. 2017, 139, 10645. (c) Zhang, B. B.; Shi, G. Q.; Yang, Z. H.; Zhang, F. F.; Pan, S. L. Angew. Chem., Int. Ed. 2017, 56, 3916. (d) Wang, X. F.; 1595
DOI: 10.1021/jacs.7b12518 J. Am. Chem. Soc. 2018, 140, 1592−1595
