Potential Nonlinear Optical Material Research Articles

Growth and characterization of pure and Ca2+ doped MnHg(SCN)4 single crystals

Manganese-mercury thiocyanate, MnHg(SCN)4, crystal is considered to be an important organometallic nonlinear optical (NLO) material exhibiting higher thermal stability and second harmonic generation (SHG) efficiency. In order to understand the effect of Ca2+ as an impurity on the physicochemical properties, we have grown pure and Ca2+ doped (with a concentration of 1 mol%) MnHg(SCN)4 single crystals by the free evaporation of solvent method and characterized structurally, chemically, optically and electrically by adopting the available standard methods. Results obtained indicate that Ca2+ doping increases significantly the optical transmittance, SHG efficiency, and DC electrical conductivity and decreases the dielectric loss factor (improves the crystal quality), and AC electrical conductivity without distorting the crystal structure. Also, the low dielectric constant (εr) values observed for both the pure and doped crystals considered at near ambient temperatures indicate the possibility of using these crystals not only as potential NLO materials (useful in the photonics industry) but also as promising low εr value dielectric materials (useful in the microelectronics industry).

Theoretical Exploration of the Layered Sandwich Cobaltacarborane as a Multi-State NLO Molecular Switch Triggered by Redox

Layered sandwich metallacarboranes have various advantages including structural diversity, tailoring ability, rich electrochemical properties, and high thermal stability and thus could be potential multifunctional nonlinear optical (NLO) materials. In this study, second-order NLO properties and the multi-state switching effect of the layered cobaltacarborane, induced by electrochemical behavior, were explored using density functional theory (DFT). The calculated first hyperpolarizabilities (β) illustrated that the NLO responses are enhanced with the increasing of layers, which was mainly attributed to the C → B intraligand charge transfer (C2B3) (ILCT) and metal-centered d → d transition (MCT) as indicated by the time-dependent (TD)DFT results. Remarkable β contrasts were observed after undergoing two sequential one-electron redox processes. Therefore, the pronounced multi-state NLO switch can be achieved. In mixed-valence systems, the metal–metal interaction plays a crucial role in the NLO responses thro...

Functional Materials Design via Structural Regulation Originated from Ions Introduction: A Study Case in Cesium Iodate System

Tailored structural regulation to achieve novel compounds with special properties is very attractive and important for functional material design. In this paper, CsIO3 was selected as a maternal structure and three new derivatives, namely, CsIO2F2, Cs3(IO2F2)3·H2O, and Cs(IO2F2)2·H5O2, were successfully prepared by introducing different units (F–, H2O, H5O2+, and IO2F2–) under hydrothermal condition for the first time. Then, the structural transformations were schematically analyzed and the corresponding properties originated from ions introduction were investigated. Therein, noncentrosymmetric CsIO3 and CsIO2F2 exhibit good nonlinear optical properties with large second-harmonic generation (SHG) effects (15 × and 3 × KH2PO4), wide band gaps (4.2 and 4.5 eV), wide transmittance ranges (∼0.27–5.5 μm), and high laser damage thresholds (15 × and 20 × AgGaS2, respectively), which shows that they are potential nonlinear optical materials in near-ultraviolet to mid-infrared. To further analyze the structure–pro...

Ruthenium Alkynyl Complexes in Non-Linear Optics

Non-linear optical (NLO) materials are able to modify the propagation characteristics of light. Such materials have a range of potential applications in advanced technologies and are therefore of considerable interest. This account summarizes the development of one class of organometallics as potential NLO materials, namely ruthenium alkynyl complexes. These are available in high yields by straightforward synthetic procedures and have good thermal and environmental stability. In studies ranging from small molecules (molecular weights ~1000) to second-generation dendrimers (with molecular weights of more than 20000), the author’s group and collaborators have assayed the NLO effects in complexes with a variety of ‘multipolar’ charge distributions (dipolar, quadrupolar, octupolar), revealing that ruthenium alkynyl complexes can be engineered to display record and near-record values of the parameters responsible for various interesting NLO effects. In particular, recent studies driven by the current focus on optimizing molecular multiphoton absorption cross-sections have afforded several examples with world-record values of these key coefficients. The author’s group has also shown that the fully reversible redox processes undergone by many ruthenium alkynyl complexes are a distinctive feature that can be exploited to afford molecular NLO switches, because the different and reversibly accessible redox forms of the complexes exhibit measurably different NLO responses. This unique type of switching has been extended in two ways to afford molecular switches with multiple accessible NLO states. First, ruthenium alkynyl complexes have been subjected to various ‘orthogonal’ (independent) switching stimuli (specifically oxidation–reduction, protonation–deprotonation, and photoisomerization), affording complexes that function as NLO switches with up to six distinct NLO states. Second, heterobimetallic complexes coupling ruthenium alkynyl and iron alkynyl centres have been prepared that exhibit multiple redox-accessible NLO states.

Influence of A-site cations on germanium iodates as mid-IR nonlinear optical materials: A2Ge(IO3)6(A = Li, K, Rb and Cs) and BaGe(IO3)6·H2O

A series of germanium iodates with a gradual change in polar [IO3]−arrangements have been searched as potential mid-IR nonlinear optical materials.

Chemical Cosubstitution-Oriented Design of Rare-Earth Borates as Potential Ultraviolet Nonlinear Optical Materials.

A chemical cosubstitution strategy was implemented to design potential ultraviolet (UV) and deep-UV nonlinear optical (NLO) materials. Taking the classic β-BaB2O4 as a maternal structure, by simultaneously replacing the Ba2+ and [B3O6]3- units with monovalant (K+), divalent (alkaline earth metal), trivalent (rare-earth metal, Bi3+) ions, and the [B5O10]5- clusters through two different practical routes, 12 new mixed-metal noncentrosymmetric borates K7MIIRE2(B5O10)3 (MII = Ca, Sr, Ba, K/RE0.5; RE = Y, Lu, Gd) as well as K7MIIBi2(B5O10)3 (MII = Pb, Sr) were successfully designed and synthesized as high-quality single crystals. The selected K7CaY2(B5O10)3, K7SrY2(B5O10)3, and K7BaY2(B5O10)3 compounds were subjected to experimental and theoretical characterizations. They all exhibit suitable second-harmonic generation (SHG) responses, as large as that of commercial KH2PO4 (KDP), and also exhibit short UV cutoff edges. These results confirm the feasibility of this chemical cosubstitution strategy to design NLO materials and that the threeselected crystals may have potential application as UV NLO materials.

Growth, spectral, optical, laser damage threshold and DFT investigations on 2-amino 4-methyl pyridinium 4-methoxy benzoate (2A4MP4MB): A potential organic third order nonlinear optical material for optoelectronic applications

In present investigation, single crystals of organic charge transfer complex, 2-amino-4-methyl pyridinium-4-methoxy benzoate (2A4MP4MB) was grown by controlled slow evaporation solution growth technique using methanol as a solvent at room temperature. Single crystal XRD analysis confirmed the crystal system and lattice parameters of 2A4MP4MB. The crystalline nature, presence of various vibrational modes and other chemical bonds in the compound have been recognized and confirmed by powder X-ray diffraction, FT-IR and FT-Raman spectroscopic techniques respectively. The presence of various proton and carbon positions in title compound was confirmed using 1H NMR and 13C NMR spectral studies. The wide optical operating window and cut-off wavelength were identified and band gap value of the title compound was calculated using UV-vis-NIR study. The specific heat capacity (cp) values of the title compound, 1.712 J g−1·K−1 at 300 K and 13.6 J g−1 K−1 at 433 K (melting point) were measured using Modulated Differential Scanning Calorimetric studies (MDSC). From Z-scan study, nonlinear refractive index (n2), nonlinear absorption (β) and third order nonlinear susceptibility (χ(3)) values were determined. The self-defocusing effect and saturable absorption behavior of the material were utilized to exhibit the optical limiting action at λ = 532 nm by employing the same continuous wave (cw) Nd: YAG laser source. The laser damage threshold (LDT) study of title compound was carried out using Nd: YAG laser of 532 nm wavelength. The Vickers’ micro hardness test was carried out at room temperature and obtained results were investigated using classical Meyer’s law. In addition, DFT calculations were carried out for the first time for this compound. These characterization studies performed on the title compound planned to probe the valuable and safe region of optical, thermal and mechanical properties to improve efficacy of 2A4MP4MB single crystals in optoelectronic device applications.

Vibrational spectroscopy, electrical characterization, nonlinear optical properties and DFT calculation of (NEt4)(H2AsO4)(H3AsO4)2

An organic-inorganic compound of tetraethylammonium dihydrogenarsenate bis(arsenic acid) salts of formula (NEt4)(H2AsO4)(H3AsO4)2, a potential new nonlinear optical material, was prepared by a slow evaporation technique and characterized by IR and Raman spectroscopy accomplished with DFT calculation and electrical-dielectrical measurements. The structure has been solved using direct method and refined by least-squares analysis. In this case, the structure consists of infinite parallel two-dimensional planes built of mutually H2AsO4−, H3AsO4 tetrahedra connected by strong O–H⋯O hydrogen bonding giving birth to trimers. The geometry, first hyperpolarizability and harmonic vibrational wavenumbers were calculated by means of density functional theory (DFT) with the B3LYP/6-31G(d) level of theory. Good consistency was found between the calculated and the experimental structure, IR, and Raman results. The first hyperpolarizability βtot of the title compound is about 1.75 times more than that of the reference crystal KDP. The complex impedance has been investigated in relation to the temperature and frequency ranges 297 and 373 K and 1 to 100 KHz, respectively. The conductivity temperature variation shows a typical Arrhenius-type behavior with a linear dependence on logarithm of conductivity. Transport properties in this material appear to be due to proton hopping mechanism.

A comparative theoretical study on the electrical and nonlinear optical properties of Li atom adsorbed on AlN and BN single-walled nanotubes.

The geometrical structures, electrical properties, and nonlinear optical (NLO) properties of AlNNT-Li and BNNT-Li nanotube systems were investigated by means of the density functional theory (DFT) method. Frontier molecular orbitals and density of states analyses show that adsorption of the Li atom can significantly narrow the wide HOMO-LUMO gaps of pure AlNNT and BNNT. The results reveal that AlNNT-Li and BNNT-Li systems containing diffuse excess electrons can be regarded as inorganic electrides. The formation of diffuse excess electrons leads to a decrease in transition energies, thereby increasing the first hyperpolarizabilities (β 0) of AlNNT-Li and BNNT-Li. This work may contribute to the development of potential high-performance NLO materials. Graphical abstract The structural characteristics and nonlinear optical properties of the AlNNT-Li and BNNT-Li systems were studied by means of density functional theory. Introduction of Li atoms greatly enhances the static first hyperpolarizabilities of AlNNT-Li and BNNT-Li.

Na2(H2en)[B5O8(OH)]2[B3O4(OH)]2 and Na3(HCOO)[B5O8(OH)]: Two Borates Co‐Templated by Inorganic Cations and Organic Compounds

The cooperative effect of inorganic and organic co‐templates led to two layered borates: centrosymmetric (CS) Na2(H2en)[B5O8(OH)]2[B3O4(OH)]2 (1; en = ethylenediamine) and noncentrosymmetric (NCS) Na3(HCOO)[B5O8(OH)] (2). Compound 1 features coupled layers extended by two different oxoboron clusters, which are rare in borates. The Na+ cations are located in the channel and hold the coupled layers in tight inorganic B–O–Na layers, while H2en2+ cations reside in channels between inorganic layers. Compound 2 is the first NCS borate directed by inorganic and organic species simultaneously and features acentric [B5O8(OH)]n2n– layers. It exhibits a good second harmonic generation efficiency of about 1.9 times that of potassium dihydrogenphosphate and is phase‐matchable, and the UV cutoff edge below 200 nm makes 2 a potential UV nonlinear optical material. Investigation of the fluorescence properties indicated that the new borates are potential blue fluorescent materials. In addition, structure elucidation revealed that host–guest symmetry matching plays a key role in the formation of CS 1 and NCS 2.

The novel link between planar m\xf6bius aromatic and third order nonlinear optical properties of metal\u2013bridged polycyclic complexes

Metal–bridged polcyclic aromatic complexes, exhibiting unusual optical effects such as near-infrared photoluminescence with particularly large Stokes shifts, long lifetimes and aggregation enhancement, have been established as unique “carbonloong chemistry”. Herein, the electronic structures, aromaticities, absorption spectra and third order nonlinear optical (NLO) responses of metal–bridged polcyclic aromatic complexes (M = Fe, Re, Os and Ir) are investigated using the density functional theory computations. It is found that the bridge–head metal can stabilize and influence rings, thus creating π–, σ– and metalla–aromaticity in an extended, π–conjugated framework. Interestingly, metal radius greatly influence the bond, aromaticity, liner and third order NLO properties, which reveals useful information to develop new applications of metal regulatory mechanism in NLO materials field. Significantly, the novel relationship between the aromaticity and third order NLO response has firstly been proposed, that the metal-bridged polycyclic complex with larger aromaticity will exhibit larger third order nonlinear optical response. It is our expectation that the novel link between aromaticity and NLO response could provide valuable information for scientists to develop the potential NLO materials on the basis of metal–bridged polycyclic complexes.

The effect of point of substitution and silver based nanoparticles on the photophysical and optical nonlinearity of indium carboxyphenoxy phthalocyanine

Abstract Indium(III) chloride 1,8(11),15(18),22(25)-tetra-(3-carboxyphenoxy) phthalocyanine ( 1 ) and indium(III) chloride 2,9(10),16(17),23(24)-tetra–(3-carboxyphenoxy) phthalocyanine ( 2 ) were covalently linked to glutathione capped silver nanoparticles (AgNPs–GSH) and silver selenide/zinc sulfide (Ag 2 Se/ZnS–GSH) quantum dots via amide bond formation. The photophysical and nonlinear optical behaviour of the metallophthalocyanines and their conjugates with nanoparticles were investigated using the open aperture Z–scan technique. Complex 2 showed enhanced photophysical properties compared to 1 . The conjugates revealed improved triplet state quantum yields (except for 1 -AgNPs-GSH which afforded lower triplet state quantum yields in comparison to 1 ) and nonlinear optical activities in comparison to the Pc complexes. The synthesized complexes, nanoparticles and their conjugates could be potential nonlinear optical materials due to their good nonlinear optical activities.

An Ultraviolet Nonlinear Optic Borate with 13-Ring Channels Constructed from Different Building Units.

Under solvothermal conditions, a chair open-framework borate, Na2B9O15(H2O)(H3O) (1), has been synthesized. Compound 1 shows regular pores of zeolites as well as nonlinear optical (NLO) properties of borates. The large 13-ring channels of the boron oxide framework are constructed from different cluster units of B3O7 and B6O13 with three-ring units. The second harmonic generation (SHG) signal intensity of 1 is similar to that of KH2PO4 (KDP) and gradually increased with larger particle size. Compound 1 is a potential UV NLO material for its short wavelength absorption edge.

Two Zeolitic Open-Framework Aluminoborates Directed by Similar Zn-Complexes.

Two three-dimensional (3D) zeolitic open-framework aluminoborates (ABOs) [Zn(ma)(en)2][AlB5O10] (1) and [Zn(ma)(en)2][AlB6O11(OH)] (2) (ma = methylamine, en = ethylenediamine) were successfully made under solvothermal conditions, which represent the first examples using similar metal complex (MC) with mixed amines as the structure-directing agents in ABOs. Notice that the central atom in the MC is coordinated by mixed amines is uncommon. However, they exhibit distinctly different structures: 1 crystallizes in a centrosymmetric [Al(B5O10)]n2n- zeolitic framework built by pentaborate (B5O10) clusters and AlO4 tetrahedra, exhibiting a 4-connected cag topology, while 2 contains hexaborate (B6O11(OH)) clusters and AlO4 groups, further alternately joined to form a noncentrosymmetric [AlB6O11(OH)]n2n- zeolitic framework with 7-/9-, 8-/10-ring helical channels and large 13-ring channels, showing a dia topology. Nonlinear optical (NLO) determination showed that 2 exhibits good second-harmonic generation response of ∼1.9 × KH2PO4 and is phase-matchable, combining the short UV cutoff edge, making 2 a potential UV NLO material.

Growth, Properties, and Theoretical Analysis of M2LiVO4 (M\u2009=\u2009Rb, Cs) Crystals: Two Potential Mid-Infrared Nonlinear Optical Materials

Mid-Infrared nonlinear optical (Mid-IR NLO) crystals with excellent performances play a particularly important role for applications in areas such as telecommunications, laser guidance, and explosives detection. However, the design and growth of high performance Mid-IR NLO crystals with large NLO efficiency and high laser-damage threshold (LDT) still face numerous fundamental challenge. In this study, two potential Mid-IR NLO materials, Rb2LiVO4 (RLVO) and Cs2LiVO4 (CLVO) with noncentrosymmetric structures (Orthorhombic, Cmc21) were synthesized by high-temperature solution method. Thermal analysis and powder X-ray diffraction demonstrate that RLVO and CLVO melt congruently. Centimeter sized crystals of CLVO have been grown by the top-seeded solution growth method. RLVO and CLVO exhibit strong second harmonic generation (SHG) effects (about 4 and 5 times that of KH2PO4, respectively) with a phase-matching behavior at 1.064 μm, and a wide transparency range (0.33–6.0 μm for CLVO). More importantly, RLVO and CLVO possess a high LDT value (~28 × AgGaS2). In addition, the density functional theory (DFT) and dipole moments studies indicate that the VO4 anionic groups have a dominant contribution to the SHG effects in RLVO and CLVO. These results suggest that the title compounds are promising NLO candidate crystals applied in the Mid-IR region.

Synthesis, Characterization, Nucleation Kinetics, Mechanical, Photo Conductivity, Birefringence and DFT Studies of Tris(thiourea) Zinc Selenate as Potential NLO Material

Semi-organic single crystals of pure tris(thiourea) zinc selenate (TTZS) were grown from aqueous solution by slow evaporation method. Nucleation kinetics of grown TTZS was extensively studied through which important nucleation parameters were calculated. Further, the fair agreement between the experimental and theoretical interfacial energy values was successfully established. X-ray diffraction studies revealed the orthorhombic nature and Pca21 space group of the title crystal. Theoretically calculated bond lengths and bond angles were found to be in accordance with that of experimental XRD values but with minor deviations. The sharp peak in the HRXRD pattern indicated the higher degree of crystallinity of the sample. The micro hardness analysis was carried out to ascertain the mechanical strength of the TTZS crystal. The mechanical studies also helped to deduce Meyer’s index, elastic modulus, yield strength, fracture toughness, elastic stiffness coefficient and brittleness index. Kurtz-Perry powder technique suggested the phase matching nature of TTZS crystal and it further indicated that the SHG efficiency of TTZS is 1.12 times as that of standard KDP. The photoconductivity analysis resulted in the higher magnitude of dark currents than the photo current which suggested the negative photo conductivity nature of the TTZS crystal. The sample showed low value of birefringence (0.0483 at 532 nm). The laser damage threshold value of TTZS was found to be 2.60 GW/cm2. The charge distribution of Mulliken atomic charges, non-linear optical (NLO) and natural bond orbital (NBO) analyses were calculated by ab-initio method. The Frontier orbital analysis was employed to arrive at the values of global chemical molecular reactivity descriptors.

Synthesis and nonlinear optical property of polycrystalline MnTeMoO6

Polycrystalline MnTeMoO6 powder has been synthesized by a new approach that MnO2 is used as the manganese source. The transformation mechanism of manganese ions in the new approach has been discussed. The nonlinear optical property of polycrystalline MnTeMoO6 has been investigated, and compared with single-crystalline samples. The transformation Mn4+ → Mn2+ may be formed directly without stable intermediates, and TeO2 may serve as catalyst. The SHG response of polycrystalline MnTeMoO6 powder is worse than that of single-crystalline powder in the same particle size distribution as its pseudo-size. The results indicate that it should pay special attention with the pseudo-size of polycrystalline powder when the potential nonlinear optical materials are screened by powder second harmonic generation measurements.

Can Coinage Metal Atoms Be Capable of Serving as an Excess Electron Source of Alkalides with Considerable Nonlinear Optical Responses?

Alkalides, as a representative kind of excess electron compounds, have been demonstrated to be potential nonlinear optical (NLO) materials with large static first hyperpolarizabilities (β0). The possibility of utilizing coinage metal atoms as a novel excess electron source to design a series of alkalides, i.e., (M@36adz)M' (M = Cu, Ag, and Au; M' = Li, Na, and K), was examined by density functional theory calculations. The alkalide characteristics of these compounds are guaranteed by their HOMOs and VIE values as well as NBO analysis. In particular, all proposed alkalides exhibit considerable first hyperpolarizabilities (β0) up to 61 590 au, indicating that they can be considered as novel NLO molecules of high performance. Moreover, a larger cage-complexant has been considered, and the resulting (Ag+@TriPip222)K- alkalide possesses a remarkably large β0 value of 180 068 au. We hope that this work will provide a new recipe for designing excess electron compounds and, on the other hand, attract more research interest and efforts in exploring new, unconventional alkalides.

Crystal structure and nonlinear optical properties of 7,8-dihydroxyaminoacenaphthalene

In this paper, 7,8-dihydroxyaminoacenaphthalene was synthesized by a convenient method. Its crystal structure was determined by X-ray diffraction. The crystal structure shows that the molecules aggregated to monoclinic crystal with space group [Formula: see text]. The semi-empirical method ZINDO was employed to study the static first hyperpolarizabilities of this compound. The static first hyperpolarizability value is [Formula: see text][Formula: see text]esu, which is 6.00 times as much as that of KH2PO4 (KDP) molecule. The results indicate that the title molecule would be potential nonlinear optical materials.

Facile Syntheses of Ba2[B4O7(OH)2] and Na[B5O7(OH)2](H2O) Borate Salts Exhibiting Nonlinear Optical Activity in the Ultraviolet.

Two novel noncentrosymmetric metal borates, Ba2[B4O7(OH)2] (1) and Na[B5O7(OH)2](H2O) (2), have been obtained by hydrothermal and surfactant-thermal means. Compound 1 consists of novel one-dimensional borate chains formed by B3O9 and B3O8 rings, assembled into a three-dimensional (3D) framework by Ba2+ cations. The structure of 2 exhibits double-helical chains constructed from B5O10 primary building units, which are interconnected via Na+ cations and H-bonding interactions to generate a 3D framework. Second-harmonic-generation (SHG) measurements show that 1 shows a phase-matching powder SHG response of ∼2.2 × KH2PO4 (KDP), while 2 exhibits a weak SHG response. The cutoff edges of 1 and 2 are ∼242 and ∼221 nm, respectively, which suggests that they are potential ultraviolet nonlinear optical (NLO) materials. Band structures and NLO properties have also been theoretically studied.