Bing-Ping Yang

Explorations of new second-order nonlinear optical materials in the potassium vanadyl iodate system.

Four new potassium vanadyl iodates based on lone-pair-containing IO(3) and second-order Jahn-Teller distorted VO(5) or VO(6) asymmetric units, namely, α-KVO(2)(IO(3))(2)(H(2)O) (Pbca), β-KVO(2)(IO(3))(2)(H(2)O) (P2(1)2(1)2(1)), K(4)[(VO)(IO(3))(5)](2)(HIO(3))(H(2)O)(2)·H(2)O (P1), and K(VO)(2)O(2)(IO(3))(3) (Ima2) have been successfully synthesized by hydrothermal reactions. α-KVO(2)(IO(3))(2)(H(2)O) and β-KVO(2)(IO(3))(2)(H(2)O) exhibit two different types of 1D [VO(2)(IO(3))(2)](-) anionic chains. Neighboring VO(6) octahedra in the α-phase are corner-sharing into a 1D chain with the IO(3) groups attached on both sides of the chain in a uni- or bidentate bridging fashion, whereas those of VO(5) polyhedra in the β-phase are bridged by IO(3) groups into a right-handed helical chain with remaining IO(3) groups being grafted unidentately on both sides of the helical chain. The structure of K(4)[(VO)(IO(3))(5)](2)(HIO(3))(H(2)O)(2)·H(2)O contains novel isolated [(VO)(IO(3))(5)](2-) units composed of one VO(6) octahedron linked to five IO(3) groups and one terminal O(2-) anion. The structure of K(VO)(2)O(2)(IO(3))(3) exhibits a 1D [(VO)(2)O(2)(IO(3))(3)](-) chain in which neighboring VO(6) octahedra are interconnected by both oxo and bridging iodate anions. Most interestingly, three of four compounds are noncentrosymmetric (NCS), and K(VO)(2)O(2)(IO(3))(3) displays a very strong second-harmonic generation response of about 3.6 × KTP, which is phase matchable. It also has high thermal stability, a wide transparent region and moderate hardness as well as an excellent growth habit. Thermal analyses and optical and ferroelectric properties as well as theoretical calculations have also been performed.

Co[HO2C(CH2)3NH(CH2PO3H)2]2: a new canted antiferromagnet.

A new cobalt(II) carboxylate-phosphonate, namely, Co[HO2C(CH2)3NH(CH2PO3H)2]2, with a layered architecture has been synthesized by hydrothermal reactions. The Co(II) ion in the title compound is octahedrally coordinated by six phosphonate oxygen atoms from four carboxylate phosphonate ligands. Neighboring CoO6 octahedra are interconnected by phosphonate groups into a 2D layer with a 4,4-net topology. Adjacent layers are further cross-linked via hydrogen bonds between the noncoordinate carboxylate groups and noncoordinate phosphonate oxygens. The ac and dc magnetic susceptibility and magnetization measurements indicate that Co[HO2C(CH2) 3NH(CH2PO3H)2]2 is a canted antiferromagnet with T(c) = 8.75 K.

Zn2(VO4)(IO3): a novel polar zinc(II) vanadium(V) iodate with a large SHG response.

The synthesis, crystal and electronic structures, and optical properties of the first zinc(II) vanadium(V) iodate, namely, Zn2(VO4)(IO3), are reported. Zn2(VO4)(IO3) crystallizes in the noncentrosymmetric (NCS) and polar space group Pc (No. 7) with a = 5.2714(8) Å, b = 10.0402(11) Å, c = 5.5070(8) Å, β = 101.326(10)°, and Z = 2. It displays a novel three-dimensional (3D) network structure composed of ZnO5, ZnO6, VO4, and IO3 polyhedra. One-dimensional (1D) chains of edge-sharing ZnO5 polyhedra and 1D chains of corner-sharing ZnO6 octahedra along the c-axis are interconnected via corner-sharing into a two-dimensional (2D) zinc oxide layer, and such layers are bridged by both VO4 tetrahedra and IO3 groups into a 3D network. The polarity in the structure is imparted by the alignment of the stereochemically active lone pairs of the iodate anions along the c-axis. The second harmonics generation (SHG) measurements on powder samples of Zn2(VO4)(IO3) under 1064-nm laser radiation revealed a large response of ∼6 × KDP, which is Type I phase-matchable. Thermal stability and optical properties, as well as theoretical calculations based on DFT methods, were also performed.

Hydrothermal syntheses, characterizations and crystal structures of three new cadmium (II) amino-diphosphonates: effects of substitute groups on the structures of metal phosphonates

Abstract Hydrothermal reactions of cadmium(II) chloride with three amino-diphosphonic acids, C6H5CH2N(CH2PO3H2)2 (H4L1), C6H5CH2CH2N(CH2PO3H2)2 (H4L2) and 4-CH3–C6H4CH2N (CH2PO3H2)2) (H4L3) resulted in three new metal amino-diphosphonates, namely, Cd(H3L1)2, 1 Cd(H3L2)2·2H2O 2 and Cd(H3L3)2 3. In all three complexes, the Cd(II) ion is octahedrally coordinated by six phosphonate oxygen atoms from six ligands. Complexes 1 and 3 have a similar structure in which the CdO6 octahedra are cross-linked by bridging ligands into a double chain along the c-axis, such double chains are further interlinked via hydrogen bonds between non-coordinated phosphonate oxygen atoms to form 〈100〉 and 〈200〉 layers with the phenyl groups of the ligands orientated toward the interlayer space. The structure of complex 2 features a 〈100〉 cadmium(II) diphosphonate layer. The effects of the substitute groups attached to the amine groups on the structures of the metal phosphonates are also discussed.

Explorations of New Second-Order Nonlinear Optical Materials in the Ternary Rubidium Iodate System: Noncentrosymmetric β-RbIO3(HIO3)2 and Centrosymmetric Rb3(IO3)3(I2O5)(HIO3)4(H2O)

Two new rubidium iodates, namely, β-RbIO3(HIO3)2 (1, P1) and Rb3(IO3)3(I2O5)(HIO3)4(H2O) (2, P21/c), have been synthesized by hydrothermal reaction and their structures determined by single-crystal X-ray diffraction. Compound 1 exhibits IO3(-) anions and neutral HIO3 molecules which are interconnected by Rb(+) cations into three-dimensional structure. Compound 2 features a two-dimensional layered structure formed by IO3(-) anions and neutral HIO3 and dimeric I2O5 molecules interconnected by Rb(+) cations. Large bulk crystal of 1 with dimensions of several millimeters has been grown. UV-vis-NIR transmission spectroscopy measurements on a slab of a polished crystal of 1 indicated that the crystal possesses a short-wavelength absorption edge onset at 305 nm. Powder second-harmonic generation (SHG) measurements on sieved crystals revealed that 1 is a type I phase-matchable material with an SHG response about 1.5 times that of KH2PO4. The Vickers hardness of crystal of 1 has been measured to be 110 HV, and the laser-induced damage threshold has been confirmed to be 18.26 J/cm(2) with a laser wavelength of 1064 nm and a pulse duration of 10 ns. Moreover, thermal stabilities and vibrational spectra for both 1 and 2 have also been studied.

Second-Order Nonlinear Optical Materials Based on Metal Iodates, Selenites, and Tellurites

In this chapter, the syntheses, structures, and Second Harmonic Generation (SHG) properties of metal iodates, selenites, and tellurites all of which contain a lone pair cation in an asymmetric coordination geometry were reviewed. A second asymmetric building unit such as distorted octahedra of the d0 transition-metal (TM) cations such as V5+, Mo6+, other cations with a stereochemically active lone pair such as Pb2+ and Bi3+, and tetrahedral groups such as BO 4 5− and PO 4 3− , can be introduced into metal iodates, selenites, and tellurites. The combination of d0 transition-metal cations with the iodate groups afforded a large number of new metal iodates, a number of which display excellent SHG properties due to the additive effects of polarizations from both types of the asymmetric units. Introducing other lone-pair cations such as Pb2+ and Bi3+ into the metal iodates is also an effective strategy to design new SHG materials. With respect to the metal selenite or tellurite systems, many compounds in the alkali or alkaline earth-d0 TM–Se(IV)/Te(IV)–O systems can also exhibit excellent SHG properties due to the additive effects of polarizations from both types of asymmetric units. Lanthanide or posttransition metal main group element-d0 TM–Se(IV)/Te(IV)–O compounds are usually structurally centrosymmetric and not SHG active, but they can also display abundant structural diversities and interesting magnetic or luminescent properties. Metal tellurites and selenites containing tetrahedral groups of the main group elements such as BO4 and PO4 may also form NCS structures with excellent SHG properties.

Explorations of a series of second order nonlinear optical materials based on monovalent metal gold(III) iodates.

The syntheses, crystal structures, and characterizations of a series of monovalent metal gold(III) iodates, namely, α-NaAu(IO3)4, β-NaAu(IO3)4, RbAu(IO3)4, α-CsAu(IO3)4, β-CsAu(IO3)4, and AgAu(IO3)4 are reported. Their structures feature Au(IO3)4(-) anions that are separated by alkali metal ions or silver(I) ions. The Au(IO3)4(-) anions in the polar α-NaAu(IO3)4, RbAu(IO3)4, and α-CsAu(IO3)4 are polar with all four iodate groups being located only above (or below) the AuO4 square plane (cis- configuration). α-NaAu(IO3)4, RbAu(IO3)4, and α-CsAu(IO3)4 display moderate strong Second-Hamonic Generation (SHG) responses of 1.17 ×, 1.33 ×, and 1.17 × KTP (KTiOPO4), respectively, and all three materials are type-I phase-matchable. The Au(IO3)4(-) anions in centrysymmetric β-NaAu(IO3)4, β-CsAu(IO3)4, and AgAu(IO3)4 are nonpolar with the four iodate groups of the Au(IO3)4(-) anion being located both above and below the AuO4 square plane (trans- configuration). IR and UV spectra, luminescent and ferroelectric properties have also been measured. Theoretical calculations of their optical properties based on density functional theory (DFT) methods were performed by using the CASTEP total-energy code.

New strategy for the in situ synthesis of single-crystalline MnWO4/TiO2 photocatalysts for efficient and cyclic photodegradation of organic pollutants

MnWO4 nano photocatalysts with plate shapes and in high yields are in situ synthesized on the surface of a porous TiO2 film by the conventional plasma electrolytic oxidation (PEO) method combined with a subsequent ambient annealing process. Transmission electron microscopy (TEM) analysis shows that the MnWO4 nano photocatalysts are single crystals free of structural defects and scanning electron microscopy (SEM) observation on the cross-section reveals that these MnWO4 nano photocatalysts are in situ grown on the porous TiO2 film surface with strong adhesion. The morphology and dimension size can be selectively tailored through controlling the reaction time, showing the simplicity and versatility of the proposed method. In addition, the photodegradation of methylene blue (MB) solution using the MnWO4/TiO2 photocatalysts demonstrated the superior photocatalytic performance with high efficiency and excellent photostability. A high photodegradation rate of MB solution of over 90% in 60 min has been achieved and a superior cyclic capability is also obtained. The superior photocatalytic performance of MnWO4/TiO2 photocatalysts can be mainly attributed to the good crystallinity, all-surface covering and strong mechanical properties of the MnWO4 nanostructures with TiO2 film. The prevailing advantage of the PEO method in combination with the ambient annealing process will open up more opportunity for the rational synthesis of a wide range of oxide photocatalysts ranging from tungstate to titanate, molybdate and vanadate for promising catalytic applications in diverse fields.

New Series of Polar and Nonpolar Platinum Iodates A2Pt(IO3)6 (A = H3O, Na, K, Rb, Cs)

A new series of platinum iodates, namely, α-(H3O)2Pt(IO3)6, β-(H3O)2Pt(IO3)6, and A2Pt(IO3)6 (A = Na, K, Rb, Cs), have been synthesized. Interestingly, among these six stoichiometrically identical compounds, α-(H3O)2Pt(IO3)6 is polar, whereas other compounds are nonpolar and centrosymmetric. They all consist of zero-dimensional [Pt(IO3)6](2-) molecular units separated by H3O(+) or A(+) cations. All of the lone electron pairs of the IO3(-) groups are aligned and almost point to one direction for α-(H3O)2Pt(IO3)6, whereas IO3(-) groups are located trans to each other in other compounds. The material, α-(H3O)2Pt(IO3)6, exhibits very strong second harmonic generation (SHG) effects, approximately 1.2 × KTiOPO4 (KTP), and is phase-matchable. Thermogravimetric analysis, elemental analysis, infrared spectra, UV-vis spectra, nonlinear optical properties, and theoretical calculations are also reported.

Three new binuclear copper(II) complexes with isonicotinic acid N-oxide: syntheses, crystal structures and properties

Three new copper(II) complexes with isonicotinic acid N-oxide (HL) and 1,10-phenanthroline (phen) as ligands, [Cu(L)(phen)(H2O)]2(NO3)2···2H2O (1), [Cu(L)(phen)(H2O)]2(ClO4)2···2H2O (2), and [Cu(L)(phen)Br]2- [Cu(L)(phen)(H2O)]2Br2···6H2O (3) have been synthesized and structurally characterized. The structures of all three complexes feature a Cu2 dimer formed by two Cu(II) ions interconnected by two bridging ligands. Each copper(II) ion has a distorted square pyramidal coordination geometry with elongated axial coordination by an aqua ligand or halogen anion. The isonicotinic acid N-oxide anion is bidentate, being coordinated to two Cu(II) ions through its N-O oxygen and one of its carboxylate oxygen atoms. Magnetic susceptibility measurements show a Curie–Weiss paramagnetic behavior characteristic of one unpaired electron for a copper(II) ion for all three complexes.