Xianggao Meng

Rb2CdBr2I2: a new IR nonlinear optical material with a large laser damage threshold.

This paper describes the synthesis, crystal structure, and photophysical properties of a new compound Rb2CdBr2I2. It crystallizes in the noncentrosymmetric space group Ama2. In the crystal, all the distorted tetrahedron [CdBr2I2](2-) groups are arranged in a way such that all the Cd-I bonds are located in the same side of the Cd atoms resulting in a net polarization. Rb2CdBr2I2 showed a powder second harmonic generation (SHG) response 4 times that of KH2PO4 (KDP). The preliminary measurement indicated that it exhibits a large laser-induced damage threshold (LDT) of 190 MW/cm(2) which is 6 times that of AgGaS2. It also exhibits a wide transparent region (0.37-14 μm) with a relatively high (up to 490 °C) thermal stability. All these indicate that Rb2CdBr2I2 is a new promising candidate for NLO materials in the IR region.

Rational assembly and luminescence properties of 2 and 3D organometallic networks using silver(I) 4-pyridylethynide and 5-pyrimidylethynide complexes as building units

4-Ethynylpyridine and 5-ethynylpyrimidine were utilized as ligands to synthesize three novel silver–ethynide complexes [(4-Py-C2Ag)3·6CF3CO2Ag·2H2O] (1), [(4-Py-C2Ag)2·4AgNO3] (2) and [(5-Pyrim-C2Ag)·3AgNO3·H2O] (3). In both 1 and 2, the [4-C5H4N(CC)Ag4]3+ units aggregate to generate linear silver chains through silver–ethynide and argentophilic interactions, which are further connected through Ag–N(pyridyl) coordination bonds to afford 2D grids, and finally linked by trifluoroacetate or nitrate groups to form a rigid 3D coordination network. However in 3, each [5-C4H3N2(CC)Ag4]3+ unit interacts with two other units through Ag–N(pyrimidyl) bonds to construct 2D honeycomb-like networks, and are also further connected by nitrate groups to generate a 3D network. It is demonstrated that the coordination modes of organic ligands play a key role in controlling the structures of the organometallic networks based on silver–ethynide complexes.

A2BiI5O15 (A = K+ or Rb+): two new promising nonlinear optical materials containing [I3O9]3− bridging anionic groups

Two new alkali metal bismuth iodates, K2BiI5O15 and Rb2BiI5O15, have been synthesized by a hydrothermal method. They are isostructural with the same noncentrosymmetric (NCS) orthorhombic space group Abm2 and contain a unique [I3O9]3− bridging anionic group. Their powders showed phase-matchable second-harmonic generation (SHG) effects 3 times that of KH2PO4 (KDP) and the laser-induced damage threshold values of 84 and 72 MW cm−2, respectively. They also exhibit a wide transparent range (up to 12 μm) and good thermal stability (450 °C).

A promising nonlinear optical material in the Mid-IR region: new results on synthesis, crystal structure and properties of noncentrosymmetric β-HgBrCl

This paper reports, for the first time, the nonlinear optical property of β-HgBrCl, which was synthesized by a reaction of Hg2Cl2 and Br2 in EtOH. This reaction also gave α-HgBrCl. And the single crystal structures of both α- and β-HgBrCl are presented and compared. β-HgBrCl shows phase-matchable powder second harmonic generation (SHG) effect of about 2 times that of KH2PO4 (KDP). Its absorption edge in UV-vis spectrum locates at 366 nm, implying a wide band gap and therefore higher laser damage threshold. It also exhibits a relatively wide transparent window (from 0.4 to 20 μm) and relatively good thermal stability.

In situ reduction from CuX2 (X = Br, Cl) to Cu(I) halide clusters based on ligand bis(2-methylimidazo-1-yl)methane

Two new coordination polymers based on copper(I) halide clusters, [Cu2(2-mBIM)Cl2]n (1) and [Cu(2-mBIM)Br]n (2) [2-mBIM = bis(2-methylimidazo-1-yl)methane], have been synthesized from an in situ reduction reaction of CuX2 (X = Cl, Br) and ligand 2-mBIM under solvothermal conditions.

Assembly of three-dimensional networks based upon silver–ethynide complexes bearing pyridyl and carboxylate groups

Two ligands with different geometries have been prepared to synthesize new silver-ethynide complexes bearing pyridyl and carboxylate groups. Reactions of 5-ethynylnicotinic acid (H(2)L1) and 5-ethynylpicolinic acid (H(2)L2) with silver nitrate afforded [Ag(2)(L1)·AgNO(3)](n) (1) and {[Ag(12)(L2)(6)·12AgNO(3)]·5H(2)O}(n) (2), respectively. Crystallographic studies revealed that in 1, the L1 ligands connect linear silver chains to form a 2D layer through silver-ethynide interactions and Ag-carboxylate coordination bonds, and subsequently the layers are further linked through Ag-N(pyridyl) coordination bonds to generate a 3D network; however in 2, the L2 ligand interacts with Ag(8) units through Ag-N, Ag-O coordination bonds, silver-ethynide interactions and π-π stacking directly to assemble a 3D network. In the solid state, both complexes are luminescent at room temperature, assigned as the intraligand n-π* and π-π* transitions.

A study on K2SbF2Cl3 as a new mid-IR nonlinear optical material: new synthesis and excellent properties

To search for a new nonlinear optical (NLO) material to be used in the mid-IR region with excellent comprehensive performance including high laser damage threshold (LDT), K2SbF2Cl3 has been synthesized by the hydrothermal method, and its potential as such a new material is evaluated for the first time. Its powder shows phase-matchable second harmonic generation (SHG) response of approximately 4 times as strong as that of KH2PO4 (KDP). Its optical band gap is 4.01 eV, which is much wider than the band gaps of the currently commercialised IR NLO crystals. This means that K2SbF2Cl3 will exhibit a much higher LDT. Its powder also exhibits excellent transparency in the range of 0.31–14 μm and good thermal stability. The relationship between the composition, crystal structure and properties is discussed. These results indicate that K2SbF2Cl3 is a promising candidate for IR NLO materials.

A promising new nonlinear optical crystal with high laser damage threshold for application in the IR region: synthesis, crystal structure and properties of noncentrosymmetric CsHgBr3

Searching for new IR nonlinear optical (NLO) crystals with high laser damage threshold (LDT) has become one of the great challenges in this field. This paper reports the synthesis, single crystal structure and properties of noncentrosymmetric CsHgBr3, which is a new crystalline phase and shows a high LDT of about 226 MW cm−2, together with good comprehensive performance. Its crystal can be obtained by reaction of CsBr and HgCl2 in acetone. It crystallizes in the trigonal space group P32 (no. 145). Its powders show a phase-matchable second harmonic generation as strong as that of KH2PO4 (KDP). It also displays excellent transparency in the range of 0.42–31 μm and is thermally stable up to 250 °C. All these behaviors make it a promising new NLO crystal in the mid-IR region.

Hg2Br3I: a new mixed halide nonlinear optical material in the infrared region

A new mixed halide, Hg2Br3I, has been synthesized in solution. It crystallizes in the noncentrosymmetric orthorhombic space group Cmc21 (no. 36). In its single crystal, the molecules are arranged in a shuttle-like mode. Its powders show a phase-matchable second harmonic generation (SHG) response of approximately 0.7 times as strong as that of KTiOPO4 (KTP). It also exhibits a wide transparent range (from 0.45 to 38 μm) and a good thermal stability. These results indicate that Hg2Br3I is a promising candidate for NLO materials in the IR region.

ABi2(IO3)2F5 (A=K, Rb, and Cs): A Combination of Halide and Oxide Anionic Units To Create a Large Second-Harmonic Generation Response with a Wide Bandgap

A family of nonlinear optical materials that contain the halide, oxide, and oxyhalide polar units simultaneously in a single structure, namely ABi2 (IO3 )2 F5 (A=K (1), Rb (2), and Cs (3)), have been designed and synthesized. They crystallize in the same polar space group (P21 ) with a two-dimensional double-layered framework constructed by [BiF5 ]2- and [BiO2 F4 ]5- units connected to each other by four F atoms, in which two [IO3 ]- groups are linked to [BiO2 F4 ]5- unit on the same side. A hanging Bi-F bond of [BiF5 ]2- unit is located on the other side via ionic interaction with the layer-inserted alkali metal ions to form three-dimensional structure. The well-ordered alignments of these polar units lead to a very strong second-harmonic generation response of 12 (1), 9.5 (2), and 7.5 (3) times larger than that of potassium dihydrogen phosphate under 1064u2005nm laser radiation. All of them exhibited a wide energy bandgap over 3.75u2005eV, suggesting that they will have a high laser damage threshold.