Pb₂B₃O_5.5(OH)₂ and [Pb₃(B₃O₇)](NO₃): Facile Syntheses of New Lead(II) Borates by Simply Changing the pH Values of the Reaction Systems

Abstract

Using lead metaborate as starting material, by only adjusting pH values of the reaction systems, a series of lead(II) borates were obtained in high yields. The new polar material, namely, Pb2B3O5.5(OH)2 (1), crystallizes in the noncentrosymmetric space group Pnn2 of the orthorhombic system. Its structure features a novel three-dimensional (3D) anionic network with large 14 member rings (MRs) tunnels composed of unique one-dimensional (1D) chains and dimeric B2O7 fragments, both of which are built up from solely BO4 tetrahedra, and the Pb(2+) cations are located at the above 14-MRs tunnels. The synergistic effect of the stereoactive lone-pairs on Pb(2+) cations in 1 produces a strong SHG response of ∼3× KDP (KH2PO4) which is type I phase-matchable. The first example of lead(II) borate nitrate, namely, [Pb3(B3O7)](NO3) (2), crystallizes in space group Pnma, and its structures features a 3D lead(II) borate cationic network structure in which (B3O7)(5-) anions are bridged by lead(II) cations, the nitrate anions are isolated, and located at the small voids of the cationic network. Thermal stability and optical properties as well as theoretical calculations based on density functional theory (DFT) methods were also performed.

A Facile Synthetic Route to a New SHG Material with Two Types of Parallel π‐Conjugated Planar Triangular Units

“…Hence, LBNO is almost optically transparent in the range of 0.34-2.50 mm ( Figure S4). The strong IR absorption peaks observed at around 1380 cm À1 and in the frequency range of 1350-500 cm À1 confirmed the existence of NO 3 and BO 3 groups, [17,[24][25][26] which is in agreement with the results obtained from the single-crystal X-ray structural analysis ( Figure S5). LBNO is thermally stable up to about 480 8C based on TGA curves ( Figure S6); the DSC diagram of LBNO exhibits two endothermic peaks at 508 and 539 8C, hence the compound melts incongruently.…”

“…Besides, the introduction of triangular [NO 3 ] À unit into the system causes Pb 3 B 3 O 7 (NO 3 ) to become more structurally divers. [17] To the best of our knowledge, however, compounds containing borate and nitrate groups are still rare. [16b, 18, 19] 3 ] À units that are properly aligned could exhibit large SHG coefficient due to the synergistic polarizations from these SHG active groups.…”

New isoformula borates with similar structures and different properties – Acentric nonlinear optical KGd[B6O10(OH)2] and centrosymmetric KHo[B6O10(OH)2]

“…Syntheses of different borates by simple changing of pH values of reaction systems was previously detected [2] and no doubt this effect plays an important role in the present case.…”

“…In centrosymmetric K, Ho-phase, which also has disorder along c* axes and tripling of cell, K and B2-positions holds the inversion center symmetry. 2 ] is similar to two latter crystals thus enlarging their group and enriching crystal chemistry.…”

A Facile Synthetic Route to a New SHG Material with Two Types of Parallel π‐Conjugated Planar Triangular Units

“…16 Recently, we have successfully prepared a series of lead‐borates with different polyborate species by only adjusting the pH value of the reaction system. Besides, the introduction of triangular [NO 3 ] − unit into the system causes Pb 3 B 3 O 7 (NO 3 ) to become more structurally divers 17. To the best of our knowledge, however, compounds containing borate and nitrate groups are still rare 16b.…”