Ya-Lan Deng (20284244)Chun-Li Hu (1397947)Jiang-Gao Mao (1397944)
The π-conjugated [C<sub>3</sub>H<sub>6+<i>x</i></sub>N<sub>6</sub>]<sup><i>x</i>+</sup> (<i>x</i> = 0–3) cations are good functional\ngroups, which\nare widely\nemployed in the preparations of nonlinear optical (NLO) and birefringent\nmaterials due to their high hyperpolarizability and optical anisotropy.\nIn this paper, the first melamine hydroxyborate [C<sub>3</sub>H<sub>7</sub>N<sub>6</sub>]<sub>3</sub>[B<sub>3</sub>O<sub>5</sub>(OH)<sub>2</sub>] (<b>MelBO-I</b>) was synthesized by the boric acid\nmelting method under the molar ratio of H<sub>3</sub>BO<sub>3</sub>:C<sub>3</sub>H<sub>6</sub>N<sub>6</sub> = 1:1. <b>MelBO-I</b> (<i>P</i>2<sub>1</sub>/<i>c</i>) exhibits a\ntwo-dimensional (2D) {[C<sub>3</sub>H<sub>7</sub>N<sub>6</sub>]<sub>3</sub>[B<sub>3</sub>O<sub>5</sub>(OH)<sub>2</sub>]}<sub>∞</sub> layer composed of [C<sub>3</sub>H<sub>7</sub>N<sub>6</sub>]<sup>+</sup> cations and [B<sub>3</sub>O<sub>5</sub>(OH)<sub>2</sub>]<sup>3–</sup> anions interconnected via hydrogen bonds. <b>MelBO-I</b> exhibits significant birefringence (Δ<i>n</i> =\n0.286@546 nm). Under the molar ratio of H<sub>3</sub>BO<sub>3</sub>/C<sub>3</sub>H<sub>6</sub>N<sub>6</sub> = 3:1, [C<sub>3</sub>H<sub>8</sub>N<sub>6</sub>]<sub>4</sub>[B<sub>12</sub>O<sub>19</sub>(OH)<sub>6</sub>] (<b>MelBO-II</b>) was isolated. In <b>MelBO-II</b> (<i>P</i>2<sub>1</sub>), highly polymerized [B<sub>12</sub>O<sub>19</sub>(OH)<sub>6</sub>]<sup>8–</sup> groups form a\n3D network through hydrogen bonding, featuring 1D tunnels of 8-membered\nand 16-membered rings filled by [C<sub>3</sub>H<sub>8</sub>N<sub>6</sub>]<sup>2+</sup> cations. <b>MelBO-II</b> is the first noncentrosymmetric\n(NCS) bifunctional melamine borate with a moderate SHG response (0.4\n× KDP) and large birefringence (Δ<i>n</i> = 0.285@546\nnm). The results indicate that incorporating [C<sub>3</sub>H<sub>6+<i>x</i></sub>N<sub>6</sub>]<sup><i>x</i>+</sup> (<i>x</i> = 0–3) cations into borate can effectively induce\nbirefringence. A high concentration of boric acid promotes the formation\nof large boric acid cluster anions and facilitates the transformation\nfrom the CS to NCS structure.
Junghwan Do (2102317)Ranko P. Bontchev (2425492)Allan J. Jacobson (1644922)
Yunling Liu (1420054)Zhan Shi (704217)Yunlong Fu (1536427)Wei Chen (23863)Baozong Li (1621120)Jia Hua (410225)Wuyang Liu (2953659)Feng Deng (553812)Wenqin Pang (2537944)
Yucheng Hao (3129726)Jian Deng (681236)Changlin Chen (18139096)Yuan Lin (79040)Haijian Li (5048213)Guangchao Qin (18523344)Kunhong Hu (2920218)
Yang Zhang (30734)Ruizhi Wang (508892)Yezhou Li (1428364)Zeyang Wang (3873793)Shu Hu (267877)Xiaoliang Yan (1945372)Yaxin Zhai (2562517)Chuang Zhang (2199421)ChuanXiang Sheng (6101819)
Ga-Lai Law (1616419)Ka-Leung Wong (2054269)Xianju Zhou (193009)Wing-Tak Wong (1616416)Peter A. Tanner (1897672)