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Polymorphs of ZnHPO3·2H2O with centrosymmetry (Cmcm) and noncentrosymmetry (C2) structures were prepared by modified solution evaporation and seed-crystal-induced secondary nucleation methods. In Cmcm-ZnHPO3·2H2O, the zinc atoms are only octahedrally coordinated, while in C2-ZnHPO3·2H2O, they feature both tetrahedral and octahedral coordination. As a result, Cmcm-ZnHPO3·2H2O features a 2D layered structure with lattice water molecules located in the interlayer space, while C2-ZnHPO3·2H2O features a 3D electroneutral framework of tfa topology connected by Zn(1)O4, Zn(2)O6, and HPO3 units. The UV-visible diffuse reflectance spectra associated with Tauc's analyses give a direct bandgap of 4.24 and 4.33 eV for Cmcm-ZnHPO3·2H2O and C2-ZnHPO3·2H2O, respectively. Moreover, C2-ZnHPO3·2H2O exhibits a weak second harmonic generation (SHG) response and a moderate birefringence for phase matching, indicating its potential as a nonlinear optical material. Detailed dipole moment calculation and analysis confirmed that the SHG response mainly derived from the HPO3 pseudo-tetrahedra.
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Two new boroantimonates, namely, KSbB2O6 and BaSb2B4O12, have been successfully synthesized through high-temperature solid state reactions. Their structures feature two types of novel anionic 3D frameworks composed of 1D chains of corner-sharing SbO6 octahedra that are interconnected by B2O5 groups. The 1D chains of corner-sharing SbO6 octahedra in polar KSbB2O6 (space group Cc) are extended along the c-axis, whereas those in the centrosymmetric BaSb2B4O12 (space group C2/c) are propagated along the [101] direction. The K(+) ions are located at the 1D tunnels of the anionic frameworks along both b- and c-axis, whereas Ba(2+) ions are located at the 1D tunnels of the anionic frameworks along both the a- and c-axis. KSbB2O6 is a polar material that displays weak SHG response, whereas BaSb2B4O12 is centrosymmetric and not SHG active. Studies on their optical properties, thermal stability, and band structure calculations based on DFT methods have been also performed.
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Cu2CdSnS4 and α/ß-Cu2ZnSiS4 meet several criteria for promising nonlinear optical materials for use in the infrared (IR) region. Both are air-stable, crystallize in noncentrosymmetric space groups, and possess high thermal stabilities. Cu2CdSnS4 and α/ß-Cu2ZnSiS4 display wide ranges of optical transparency, 1.4-25 and 0.7-25 µm, respectively, and have relatively large second-order nonlinearity as well as phase matchability for wide regions in the IR. The laser-damage threshold (LDT) for Cu2CdSnS4 is 0.2 GW/cm(2), whereas α/ß-Cu2ZnSiS4 has a LDT of 2.0 GW/cm(2) for picosecond near-IR excitation. Both compounds also exhibit efficient third-order nonlinearity. Electronic structure calculations provide insight into the variation in properties.
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In response to the prevalent issue of thiram as a common pesticide residue on the surface of fruits and vegetables, our research team employed an acidic hydrated metal salt low co-fusion solvent to dissolve cellulose lysis slurry. Subsequently, a regenerated cellulose membrane (RCM) was successfully prepared via sol-gel method. Uniformly sized Ag nanoparticles (NPs) were deposited on RCM utilizing the continuous ion layer adsorption and reaction (SILAR) technique. The resulting Ag NPs/RCM flexible surface-enhanced Raman spectroscopy (SERS) substrates exhibited a minimum detection limit of 5 × 10-9 M for Rhodamine 6G (R6G), demonstrating good uniformity (RSD = 4.86 %) and reproducibility (RSD = 3.07 %). Moreover, the substrate displayed a remarkable sensitivity of 10-10 M toward thiram standard solution. Given its inherent flexibility, the substrate proves advantageous for the detection of three-dimensional environments such as fruit and vegetable surfaces, and its practicality has been confirmed in the detection of thiram residue on apples, tomatoes, pears, and other fruits and vegetables.
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Nanopartículas Metálicas , Tiram , Tiram/análise , Verduras/química , Frutas/química , Nanopartículas Metálicas/química , Reprodutibilidade dos Testes , Prata/química , Análise Espectral Raman/métodos , Celulose/análiseRESUMO
A new alkali-metal borogermanate with noncentrosymmetric structure, namely, Cs2GeB4O9, has been discovered, and a large crystal with dimensions of 20 × 16 × 8 mm(3) has been grown by a high-temperature top-seeded solution method using Cs2O-B2O3 as a flux. The compound crystallizes in the tetragonal space group I4 with a = b = 6.8063(2) Å, c = 9.9523(7) Å, V = 461.05(4) Å(3), and Z = 2. It features a three-dimensional anionic open framework based on GeO4 tetrahedra and B4O9 clusters that are interconnected via corner-sharing, forming one-dimensional channels of nine-/ten-membered rings along the a and b axes, which are occupied by Cs(+) cations. Cs2GeB4O9 exhibits a very high thermal stability with a melting point of 849 °C, and it possesses a short-wavelength absorption edge onset at 198 nm determined by UV-vis transmission spectroscopy measurements on a slab of polished crystal. Powder second-harmonic generation (SHG) measurement on sieved crystals reveals that Cs2GeB4O9 is a type I phase-matchable material with a strong SHG response of about 2.8 × KH2PO4. The preliminary investigation indicates that Cs2GeB4O9 is a new promising second-order nonlinear-optical crystalline material.
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As a widely used industrial additive of plastic products, phthalate ester (PAE) plasticizers can easily migrate into food, threatening human health. In this work, we proposed a rapid, precise, and reliable method to detect PAE plasticizers in edible oils by using surface-enhanced Raman spectroscopy (SERS) technology. A two-dimensional (2D) silver plate synergizing with a nanosilver sol was prepared as a substrate for SERS to detect potassium hydrogen phthalate (PHP), a hydrolysate of a PAE plasticizer. Detection conditions, such as pH values, drying times, and hydrolysate interference, were optimized. The working curve was well fitted with a linear parameter R2 of 0.9994, and the minimum detection limit was evaluated as 10-9 mol/L. Furthermore, the detection accuracy was supported by five edible oil samples. Therefore, using SERS technology to detect PHP is expected to provide an avenue for PAE plasticizer detection in oils and fats, and it features promising potential applications in food safety.
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Nanopartículas Metálicas , Ácidos Ftálicos , Humanos , Plastificantes/química , Análise Espectral Raman/métodos , Óleos , Nanopartículas Metálicas/químicaRESUMO
Diarrheal shellfish toxins are considered one of the most lethal red tide algae toxins in the worldwide. In this work, we propose an Ag NPs-loaded bacterial cellulose membrane (BCM) surface-enhanced Raman scattering (SERS) sensor based on an aptamer (Apt) for the ultrasensitive detection of dinophysistoxin (DTX-1), a type of diarrheal shellfish toxin. During drying, Ag NPs can be further densified on "gel-like" BCM to form high-density SERS "hot spots". We developed the "Apt-SH@Ag NPs@BCM" SERS sensor and used the competition of DTX-1 and complementary base (Cob) in the process of base complementary pairing to achieve SERS detection of DTX-1, with a minimum detection limit of 9.5 × 10-10 mol/L. Sample assays showed DTX-1 recovery rates ranging from 95.8% and 108.2% and the detection results were comparable to those obtained by LC-MS. Therefore, this work holds great potential for detecting of toxic substances in shellfish products, especially for the oyster (portuguese oyster) and mussel (blue mussel).
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Celulose , Nanopartículas Metálicas , Humanos , Prata/química , Nanopartículas Metálicas/química , Toxinas Marinhas/toxicidade , Frutos do Mar/análise , Diarreia , Análise Espectral Raman/métodosRESUMO
Two novel alkaline-earth zincophosphites, namely CaZn(HPO3)2 and Ba2Zn(HPO3)3, were successfully synthesized under hydrothermal conditions. CaZn(HPO3)2 exhibits a three-dimensional (3D) anionic framework with a 6-connected uni-nodal pcu α-Po primitive cubic topology, constructed by unique Zn2O8 dimers and HPO3 pseudo-tetrahedra, while Ba2Zn(HPO3)3 displays one-dimensional (1D) [Zn(HPO3)3]4- anionic chains. It is worth mentioning that CaZn(HPO3)2 represents the first example of an alkaline-earth zincophosphite compound with a 3D framework structure. Our research also revealed the importance of both alkaline earth cation sizes and Zn/P ratios in anionic open-framework formation. The crystal structures of both compounds were further verified by energy dispersive spectroscopy, IR spectroscopy and Raman spectroscopy. Optical diffuse reflectance spectra, coupled with Tauc's fitting, revealed direct bandgaps with energy values of 4.33 and 4.48 eV for CaZn(HPO3)2 and Ba2Zn(HPO3)3, respectively, which differ from the prediction of theoretical calculations. Density of states calculations were conducted to reveal the origin of the bandgaps and bond interactions. Both compounds exhibited moderate birefringence values. This work may have implications for the design and synthesis of novel metal phosphites with desired properties.
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Two new barium borogermanates with two types of novel structures, namely, Ba(3)[Ge(2)B(7)O(16)(OH)(2)](OH)(H(2)O) and Ba(3)Ge(2)B(6)O(16), have been synthesized by hydrothermal or high-temperature solid-state reactions. They represent the first examples of alkaline-earth borogermanates. Ba(3)[Ge(2)B(7)O(16)(OH)(2)](OH)(H(2)O) crystallized in a polar space group Cc. Its structure features a novel three-dimensional anionic framework composed of [B(7)O(16)(OH)(2)](13-) polyanions that are bridged by Ge atoms with one-dimensional (1D) 10-membered-ring (MR) tunnels along the b axis. The Ba(II) cations, hydroxide ions, and water molecules are located at the above tunnels. Ba(3)Ge(2)B(6)O(16) crystallizes in centrosymmetric space group P1. Its structure exhibits a thick layer composed of circular B(6)O(16) units connected by GeO(4) tetrahedra via corner sharing, forming 1D 4- and 6-MR tunnels along the c axis. Ba1 ions reside in the tunnels of the 6-MRs, whereas Ba2 ions are located at the interlayer space. Both compounds feature new types of topological structures. Second-harmonic-generation (SHG) measurements indicate that Ba(3)[Ge(2)B(7)O(16)(OH)(2)](OH)(H(2)O) displays a weak SHG response of about 0.3 times that of KH(2)PO(4). Optical, thermal stability, and ferroelectric properties as well as theoretical calculations have also been performed.
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Three novel rubidium borogermanates with three types of noncentrosymmetric structures, namely, RbGeB(3)O(7), Rb(2)GeB(4)O(9), and Rb(4)Ge(3)B(6)O(17), have been synthesized by high-temperature solid-state reactions in platinum crucibles. The structure of RbGeB(3)O(7) features a three-dimensional (3D) anionic framework composed of cyclic B(3)O(7) groups corner-sharing GeO(4) tetrahedra. The structure of Rb(2)GeB(4)O(9) shows a 3D anionic framework based on B(4)O(9) clusters connected by GeO(4) tetrahedra via corner sharing. The structure of Rb(4)Ge(3)B(6)O(17) is a novel 3D anionic framework composed of cyclic B(3)O(8) groups, Ge(2)O(7) dimers, and GeO(4) tetrahedra that are interconnected via corner sharing. Second harmonic generation (SHG) measurements indicate that RbGeB(3)O(7), Rb(2)GeB(4)O(9), and Rb(4)Ge(3)B(6)O(17) display moderate SHG responses that are approximately 1.3, 2.0, and 1.3 × KH(2)PO(4) (KDP), respectively, which are slightly smaller than those from theoretical calculations (about 3.7, 2.8, and 2.4 × KDP, respectively).
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Two new acentric borogermanates, Ca(10)Ge(16)B(6)O(51) (Pba2) and Cd(12)Ge(17)B(8)O(58) (P4), have been successfully synthesized by high-temperature solid-state reactions of CaCO(3) (or CdCO(3)), GeO(2), and H(3)BO(3). Both structures display the same one-dimensional (1D) [Ge(4)O(12)](n) chains composed of GeO(4) tetrahedra and GeO(6) octahedra. In Ca(10)Ge(16)B(6)O(51), neighboring 1D [Ge(4)O(12)](n) chains are condensed into a two-dimensional (2D) [Ge(4)O(10.75)](n) layer via corner sharing, and such layers are further interconnected by "isolated" BO(4) tetrahedra and B(2)O(7) dimers into a three-dimensional (3D) framework, forming 1D tunnels of 5-, 6-, and 7-MRs along the c axis that are occupied by Ca(2+) cations. In Cd(12)Ge(17)B(8)O(58), neighboring 1D [Ge(4)O(12)](n) chains are interconnected into a [Ge(4)O(10.5)](n) open framework via corner sharing with large pores filled by big [Ge(B(2)O(7))(4)](28-) clusters, leading to formation of three types of 1D tunnels of 5-, 6-, and 7-membered rings (MRs) along the c axis which are occupied by the Cd(2+) cations. Both compounds are transparent in the range of 0.3-6.67 µm and exhibit very weak SHG responses.
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Nano α-glycine crystals, γ-glycine crystals, and amorphous solid dispersion (ASD) of glycine were prepared through solvent-free ball milling of commercial α-glycine. The solid-state polymorph conversion of glycine from α to γ was completely realized by ball milling with 0.2 wt.% NaCl for 1 h or by ball milling with 0.02 wt.% NaCl for 1 h with subsequent storage for one week. The ASD of glycine was prepared by ball milling α-glycine with an equal amount of CaCl2 for 1 h. We studied the effect of inorganic salt types and their concentrations on the extent of polymorph conversion and amorphization of glycine in our experiments. This solvent-free ball milling method could be used for the synthesis of polymorphs and amorphous phase of drugs and other organic materials.
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Glicina , Cloreto de Sódio , Estabilidade de Medicamentos , SolventesRESUMO
The new, quaternary diamond-like semiconductor (DLS) Cu4MnGe2S7 was prepared at high-temperature from a stoichiometric reaction of the elements under vacuum. Single crystal X-ray diffraction data were used to solve and refine the structure in the polar space group Cc. Cu4MnGe2S7 features [Ge2S7]6- units and adopts the Cu5Si2S7 structure type that can be considered a derivative of the hexagonal diamond structure. The DLS Cu2MnGeS4 with the wurtz-stannite structure was similarly prepared at a lower temperature. The achievement of relatively phase-pure samples, confirmed by X-ray powder diffraction data, was nontrival as differential thermal analysis shows an incongruent melting behaviour for both compounds at relatively high temperature. The dark red Cu2MnGeS4 and Cu4MnGe2S7 compounds exhibit direct optical bandgaps of 2.21 and 1.98 eV, respectively. The infrared (IR) spectra indicate potentially wide windows of optical transparency up to 25 µm for both materials. Using the Kurtz-Perry powder method, the second-order nonlinear optical susceptibility, χ(2), values for Cu2MnGeS4 and Cu4MnGe2S7 were estimated to be 16.9 ± 2.0 pm V-1 and 2.33 ± 0.86 pm V-1, respectively, by comparing with an optical-quality standard reference material, AgGaSe2 (AGSe). Cu2MnGeS4 was found to be phase matchable at λ = 3100 nm, whereas Cu4MnGe2S7 was determined to be non-phase matchable at λ = 1600 nm. The weak SHG response of Cu4MnGe2S7 precluded phase-matching studies at longer wavelengths. The laser-induced damage threshold (LIDT) for Cu2MnGeS4 was estimated to be â¼0.1 GW cm-2 at λ = 1064 nm (pulse width: τ = 30 ps), while the LIDT for Cu4MnGe2S7 could not be ascertained due to its weak response. The significant variance in NLO properties can be reasoned using the results from electronic structure calculations.
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Four new alkali metal aluminum/gallium iodates, namely A2M(IO3)4(H0.5IO3)2 (A = K, Rb and M = Al, Ga), have been successfully synthesized via a hydrothermal reaction and structurally characterized through single-crystal X-ray diffraction analysis. These compounds are isostructural and crystallize in the P1[combining macron] space group (no. 2) with one formula unit in each unit cell. The rare half-protonated H0.5IO3 building units were identified, and their structure feature isolated [M(IO3)4(H0.5IO3)2]2- anions, which are separated by alkali metal cations. The optical diffuse reflectance spectroscopy measurements associated with the Tauc analysis showed direct energy gaps, which are in good agreement with the theoretical calculation prediction. Moreover, this study also indicates that the electronic properties of these compounds are mainly determined by the IO3 and H0.5IO3 anionic units, and the alkali metal cations show a remarkable effect on their energy gap values, whereas the impacts of the group 13 elements aluminum and gallium are insignificant.
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Two new alkali boroselenites RbSe3B2O9(OH) and CsSe3B2O9(OH) have been synthesized by traditional solid-state reactions. Single-crystal X-ray diffraction study indicated that they are isostructural and adopt a new type of structure, which crystallizes in the noncentrosymmetric space group P212121. Optical diffuse reflectance spectrum studies emphasized that both are indirect optical transitions with values of 3.79 and 4.17 eV for RbSe3B2O9(OH) and CsSe3B2O9(OH), respectively. Optical analysis revealed a broad transparency window in the 0.3-8.5 µm region for both compounds. In addition, RbSe3B2O9(OH) featured a relatively weak second-harmonic-generation response, and for CsSe3B2O9(OH), the response is 0.8-times that of KH2PO4. Theoretical calculations of band structure, density of state, and linear and nonlinear optical properties were also performed to get insight into the relationships between electronic structures and their optical properties.
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Herein, unprecedented NLO-brominated tin hypophosphites, namely [Sn2(H2PO2)3]Br, were discovered via a facile surfactant-induced method, which displayed a moderate powder SHG intensity (3.0 × KDP) in type - I phase matching behavior. This complex has high chemical and thermal stability at room temperature. DFT calculations and SHG coefficient analyses revealed that the alignment of the SHG-active-units SnO3 trigonal pyramids and Br- anions in its structure mainly contribute to the macroscopical SHG behaviors.
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Correction for 'Infrared nonlinear optical properties of lithium-containing diamond-like semiconductors Li2ZnGeSe4 and Li2ZnSnSe4' by Jian-Han Zhang et al., Dalton Trans., 2015, 44, 11212-11222.
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Two new lithium-containing diamond-like semiconductors, Li2ZnGeSe4 and Li2ZnSnSe4, have been prepared by high-temperature, solid-state synthesis. Single crystal X-ray diffraction reveals that both compounds adopt the wurtz-kesterite structure type, crystallizing in the noncentrosymmetric space group Pn. X-ray powder diffraction coupled with Rietveld refinement indicates the high degree of phase purity in which the materials are prepared. Both compounds display optical bandgaps around 1.8 eV, wide optical transparency windows from 0.7 to 25 µm and type-I phase matched second harmonic generation starting at 2500 nm and persisting deeper into the infrared. Using the Kurtz powder method, the second-order nonlinear optical coefficient, χ((2)), was estimated to be 19 and 23 pm V(-1) for Li2ZnGeSe4 and Li2ZnSnSe4, respectively. Using a 1064 nm incident laser beam with a pulse width (τ) of 30 ps both compounds exhibit a laser damage threshold of 0.3 GW cm(-2), which is higher than that of the AgGaSe2 reference material measured under identical conditions. Differential thermal analysis shows that the title compounds are stable up to 684 and 736 °C, respectively. These properties collectively demonstrate that Li2ZnGeSe4 and Li2ZnSnSe4 have great potential for applications in tunable laser systems, especially in the infrared and even up to the terahertz regime. Electronic structure calculations using a plane-wave pseudopotential method within density functional theory provide insight regarding the nature of the bandgap and bonding.
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A family of new luminescent lanthanide MOFs have been synthesized and display a strong second-harmonic generation response, which is 6.0 times that of KDP and phase matchable. The LnMOFs also exhibit typical luminescence emissions with high quantum yields (up to 70.0% for Tb).
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Elementos da Série dos Lantanídeos/química , Substâncias Luminescentes/química , Compostos Orgânicos/química , Cristalografia por Raios X , Conformação Molecular , Teoria QuânticaRESUMO
The first examples of lanthanide(III) organoarsonates, Ln(L(1))(H(2)O)(3) (Ln = La (1), H(3)L(1) = 4-hydroxy-3-nitrophenylarsonic acid), Ln(L(1))(H(2)O)(2) (Ln = Nd (2), Gd (3)), and mixed-ligand lanthanide(III) organoarsonates, Ln(2)(HL(1))(2)(C(2)O(4))(H(2)O)(2) (Ln = Nd (4), Sm (5), Eu (6)), were hydrothermally synthesized and structurally characterized. Compounds 1-3 feature a corrugated lanthanide arsonate layer, in which 1D lanthanide arsonate inorganic chains are further interconnected via bridging L(1)(3-) ligands. Compounds 4-6 exhibit a complicated 3D network. The interconnection of the lanthanide(III) ions by the bridging arsonate ligand leads to the formation of a novel 3D framework with long narrow 1D tunnels along the a-axis, with the oxalate anions are located at the above tunnels and bridging with lanthanide(III) ions. Compounds 2 and 4 exhibit the characteristic emission bands of the Nd(III) ion, whereas compound 6 displays the characteristic emission bands of the Eu(III) ion. The magnetic properties of compounds 3-6 were also investigated.