Kinetics of Desolvation of Related Organic Inclusion Compounds

Abstract

This study dealt mainly with the structure-reactivity relationship of selected organic inclusion compounds. The crystal structures of the inclusion compounds of three related hosts, 2,2′–bis(2,7–di-tert-butyl-9–hydroxy-9–fluorenyl)biphenyl, 2,2′–bis (2,7–dichloro-9–hydroxy-9–fluoienyl)biphenyl and 2, 2′–bis(2,7-dibromo-9–hydroxy-9–fluorenyl)biphenyl with 1,4–dioxane (Compound 1), 1,3–dioxane (Compound 2) and 1,3–dioxolane (Compound 3) respectively were elucidated, using single crystal X-ray crystallography. It was found that the guests were either located in channels or constricted channels (cavities), formed by the host framework. The kinetics of desolvation of these compounds were studied and their activation energies were compared.     

Second harmonic generation in ferroelectric liquid crystals and their mixtures

The second harmonic generation (SHG) in the ferroelectric liquid crystal (FLC) state has been studied as functions of electric field strength, rotating angle, temperature and molecular structure. It has been confirmed that a sharp angularly phase-matching curve of the SHG controlled by an electric field is observed even in the liquid crystal. The temperature dependences of the phase-matched SHG and Maker fringe in the ferroelectric phase have also been studied, and temperature dependences of non-linear optical coefficients obtained. The SHG in several kinds of FLC and dye doped FLC have also been measured, and the enhancement of SHG realized by means of doping the FLC with several kinds of dye.     

Electron crystallography and organic materials with non-linear optical properties

Results of electron microscopic studies of crystal structures of a number of bis-benzylidene cyclohexanones are presented. It is shown that some of these compounds are efficient crystalline non-linear optically active (NLO) chromophores with second harmonic generation (SHG) properties. Appropriately functionalized chromophores of this type can be used as a polycondensation comonomer to produce partly crystalline main-chain NLO-active polymers. Electron diffraction crystal structural data, obtained for very small crystals, allowed us to get reasonable estimations of macroscopic crystal NLO-coefficients, relating quantum-chemically calculated molecular first hyperpolarizability components to crystal axes.     

Syntheses and characterization of new mid-infrared transparency compounds: centric Ba2BiGaS5 and acentric Ba2BiInS5

Two new mid-infrared transparency compounds, centric Ba(2)BiGaS(5) (1) and acentric Ba(2)BiInS(5) (2), were synthesized from a high-temperature solid-state reaction in evacuated closed silica tubes. Their crystal structures were determined by a single crystal X-ray diffraction method at 293 K. The results of crystal structure solution indicate that compound 1 crystallizes in the centrosymmetric space group Pnma with trans- (1)(∞)[BiGaS(5)](4-) chain structure, while compound 2 crystallizes in the noncentrosymmetric polar space group Cmc2(1) with cis- (1)(∞)[BiInS(5)](4-) chain structure. Two types of lone-pair electrons alignment fashions within (1)(∞)[BiMS(5)](4-) chains result in destructive (for 1) or constructive (for 2) dipole moments, as illustrated in the crystal structures and the partial electron density maps based on the first-principles electronic structure computations. Powder second-harmonic generation (SHG) experiments with a 2.05 μm pumping laser show that the SHG efficiency of the polar compound 2 is approximately 0.8 times that of KTiOPO(4) (KTP) reference. Furthermore, SHG signal intensity measurements using different size particles of powder samples indicate that compound 2 can also achieve type I phase-matching, which makes the compound promising for practical applications.     

Second harmonic generation in ferroelectric liquid crystals and their mixtures

Abstract

The second harmonic generation (SHG) in the ferroelectric liquid crystal (FLC) state has been studied as functions of electric field strength, rotating angle, temperature and molecular structure. It has been confirmed that a sharp angularly phase-matching curve of the SHG controlled by an electric field is observed even in the liquid crystal. The temperature dependences of the phase-matched SHG and Maker fringe in the ferroelectric phase have also been studied, and temperature dependences of non-linear optical coefficients obtained. The SHG in several kinds of FLC and dye doped FLC have also been measured, and the enhancement of SHG realized by means of doping the FLC with several kinds of dye.     

Influence of pi-stacking on the resonant enhancement of the second-order nonlinear optical response of dipolar chromophores

The wavelength-dependent second-harmonic generation (SHG) efficiency of two simple dipolar chromophores, 4-NO2C6H4N(H)Bun (1) and 4-NO2C6H4SN(H)But (2), was compared in solution and in the solid state. Hyper-Rayleigh scattering measurements at 532 nm provided comparable molecular first hyperpolarizabilities. Both compounds crystallize in non-centrosymmetric space groups, but a more efficient arrangement of dipole moments results in a significantly larger deff value for 2. Kurtz-Perry experiments from 450 to 700 nm revealed an important difference in the resonant component of the nonlinear optical responses of these compounds; the SHG efficiency of crystalline 1 depends more strongly on the incident wavelength than that of 2. This would be in contradiction with the TD-DFT excitation energies calculated for these molecules, but the observation can be explained by the resonant contribution from low-energy interchromophore excitations enabled by pi-stacking in the crystal of 1.     

芳基膦(胂)酸及其盐的合成、结构与倍频效应研究

本文基于将无机非线性光学材料的有效基团(畸变阴离子基团)及有机共轭体系结合为一体的设想,用改进的Doak-Freedman法合成了一系列芳基膦(胂)酸及其盐共25个化合物,讨论了分子的电子性质及其在晶体中的排列方式.实验结果表明,在这类化合物的分子内存在着一定的电荷转移;对甲苯膦酸的晶体结构分析表明,分子间存在着氢键作用,使分子呈二聚的排列方式.在所合成的化合物中,有6种表现出宏观倍频效应.     

Inclusion Crystals of Cedrol and Phenol-type of Compounds for Second-Order Nonlinear Optical Application

This present paper reports that the cedrol and phenol-type of inclusion crystals exhibit SHG effect. These inclusion crystals with noncentrosymmetrical structure possess lower cutoff wavelength(290-380 nm) and higher reflection rate (300-1200 nm), and show a great promising application prospect.     

黄铜矿型铜基硫属半导体材料的电子结构和光学性质

采用基于赝势平面波基组的密度泛函理论方法, 对具有黄铜矿结构的6种CuXY₂(X=Ga, In; Y=S, Se, Te)晶体的构型、 电子结构、 线性及二阶非线性光学性质进行了研究. 结果表明, 6种CuXY₂均为直接带隙半导体, 具有相似的能带结构. 当X原子相同时, 随着Y原子按S→Se→Te依次改变时, 体系的静态介电常数、 静态折射率和静态倍频系数(d₃₆)依次递增. 在占据带中, 位于价带顶附近的能带对体系倍频效应影响最为显著, 该系列化合物的能带主要成分为Cu的3d轨道和Y原子价层p轨道; 对于空能带, 对倍频系数影响较大的是以X原子价层p轨道为主要成分的能带. 6种晶体中, CuInSe₂晶体具有较高的光电导率并对太阳光具有较好的吸收性能. 综合考虑体系的双折射率和倍频效应等因素, CuGaS₂和CuGaSe₂ 2种晶体在二阶非线性光学领域具有潜在的应用价值.     

Enhancement of second harmonic generation in helical Sc liquid crystals

In a ferroelectric liquid crystal, a special type of phase-matching for optical second harmonic generation (SHG) is possible, where two counter-propagating fundamental waves create second harmonic waves at the edge of the selective reflection band. We compute the SHG intensity in such a situation and show that, at slight detuning from exact phase-matching, useful resonance enhancement can be obtained. A considerable amount of SHG also appears when the second harmonic frequency is in the reflection band, where the SHG wave is non-propagating.     

Synthesis,growth, structural,spectroscopic, crystalline perfection,second harmonic generation (SHG) and thermal studies of 2-aminopyridinium picrate (2APP): A new nonlinear optical material

Single crystal growth, spectroscopic, relative second harmonic generation (SHG) efficiency and thermal analysis of 2-aminopyridinium picrate (2APP) is reported for the first time. Crystals were grown by the slow evaporation solution technique using methanol as a solvent. The crystal system and lattice parameters were confirmed by single crystal and powder XRD analyses. FT-IR and FT-Raman spectroscopic studies were carried out to identify the functional groups and vibrational modes present in the grown crystal. Crystalline perfection of the grown crystal was assessed by high-resolution XRD and the results reveal that the crystal is reasonably good. SHG efficiency was measured using Kurtz powder technique. Thermogravimetric (TG) and differential thermal analysis (DTA) studies were carried out and show that the grown single crystal is stable up to 223 °C.     

Influence of the cation size on the framework structures and space group centricities in AMo2O5(SeO3)2 (A = Sr, Pb, and Ba)

Two new quaternary mixed-metal selenites, SrMo(2)O(5)(SeO(3))(2) and PbMo(2)O(5)(SeO(3))(2), have been synthesized as crystals and pure polycrystalline phases by standard solid-state reactions using SrMoO(4), PbO, MoO(3), and SeO(2) as reagents. The crystal structures of the reported materials have been determined by single-crystal X-ray diffraction. SrMo(2)O(5)(SeO(3))(2) and PbMo(2)O(5)(SeO(3))(2) are isostructural and crystallized in the triclinic centrosymmetric space group P1? (No. 2). The reported materials exhibit chain structures consisting of MoO(6) octahedra and asymmetric SeO(3) polyhedra. Complete characterizations including IR spectroscopy and thermal analyses for the compounds are also presented, as are dipole moment calculations. In addition, the powder second-harmonic-generating (SHG) properties of noncentrosymmetric polar BaMo(2)O(5)(SeO(3))(2) have been measured using 1064 nm radiation. Through powder SHG measurement, we are able to determine that BaMo(2)O(5)(SeO(3))(2) has a SHG efficiency of approximately 80 times that of α-SiO(2). Additional SHG measurements reveal that the material is phase-matchable (type 1). A detailed cation size effect on the symmetry and framework structure is discussed.     

Complexation with Diol Host Compounds. Part 35: Inclusion Compounds of 1,1,6,6-Tetraphenylhexa-2,4-diyne-1,6-diol with CCl4, CHCl3, CH2Cl2 and CH3CN

Inclusion compounds were formed with 1,1,6,6-tetraphenylhexa-2,4-diyne-1,6-diol (H) and carbon tetrachloride, chloroform, dichloromethane and acetonitrile. 1 (H·1/2CCl⁴), 2 (H·1/2CHCl³) and 3 (H·1/2CH²Cl²) are true clathrates with the guest molecules situated in cages created by the host. 4 (H·2CH³CN) exhibits a different packing arrangement with the guest molecules located in channels. The crystal structures and stability of these inclusion compounds were investigated.     

Study on second harmonic generation of 10-hydrocarbylacridones

Values of second-order polarizabilities (beta(xxx)), the composite magnitude (beta(CT microg)) of molecular hypersusceptibilities and the second harmonic generation (SHG) of microcrystal were used to characterize and evaluate the second-order nonlinear optical performance of 10-hydrocarbylacridones. Using Nd:YAG as a laser source, the SHG values of these compounds in powder as compared with urea powder were obtained, compared with the calculated values of beta(CT microg) and beta(xxx) found by solvatochromic method. The results showed that the SHG values of compounds 1, 2, and 5 are larger than that of urea. Compound 5 has a highest beta(CT microg) value among the 12 compounds. Although the different electronegativities of hydrocarbyl (R) attached to nitrogen atom should have an effect on the extent of intralmolecular charge-transfer and further influence SHG, beta(CT microg) or beta(xxx) values, the relationships between electronegativity of R and SHG, beta(CT microg) or beta(xxx) could not be found. But it is found that the bigger the donating-electron ability of R, the longer the maximum absorption wavelength of 10-hydrocarbylacridone molecules.     

Cation‐Tuned Synthesis of Fluorooxoborates: Towards Optimal Deep‐Ultraviolet Nonlinear Optical Materials

The development of new nonlinear optical (NLO) materials for deep‐ultraviolet (DUV) applications is in great demand. However, the synthesis of an ideal DUV NLO crystal is a serious challenge. Herein, three new alkali‐metal fluorooxoborates, AB₄O₆F (A=K, Rb, and Cs, and a mixed cation between two of them), were successfully synthesized by cation regulation. It is found that all reported compounds exhibit short UV absorption edges (<190 nm), and show second harmonic generation (SHG) responses ranging from 0.8 to 1.9 KH₂PO₄ (KDP). Interestingly, by judicious selection of the A‐site alkali‐metal cations, the arrangement of NLO‐active structural units is fine‐tuned to an optimal configuration, which contributes to large SHG responses.     

Hyper-Rayleigh scattering as a means of monitoring crystal nucleation in solution

Hyper-Rayleigh scattering is revealed as a very sensitive monitor of cluster formation in solution, and as a means of studying the mechanism of crystal nucleation in molecular species. Two compounds are selected with particularly high second harmonic generation (SHG) powers in the crystalline state and experimental conditions are defined allowing the measurement of the beta value for one of these as 18+/-1x10(-30) esu. It is found to agree with current theoretical prediction of 20x10(-30) esu. In the more powerful of these, two photon induced fluorescence is found to be partly responsible for the SHG. The solubilities of both compounds in methanol are measured and it is observed that these differ by a factor of ten. When the solution concentration is increased beyond 45% of the saturation value, the quadratic coefficient exhibits non-linear behaviour with respect to concentration. Additionally, the widths of the distributions of the HRS signals increase initially with concentration as expected, but, beyond 45% saturation concentrations, these narrow again. These phenomena are interpreted as indicators of cluster formation in these solutions well below saturation concentrations. A future experimental design is proposed in which the coherent component will yield information on the organisation of the molecules in such clusters.     

2,4,6-三苯乙烯基均三嗪（TSTA）的结构及其光学性质

制备了2，4，6一三苯乙烯基均三嗪（TSTA）的晶体，用四圆X射线衍射法测得 该晶体属于正交晶（No.36），晶体结构不仅非中心对称，而且具有极性，分子构 型为微弯曲的平面三角形．该化合物独特的分子结构和晶体构导致了其二阶非线性 光学效应，在1064nm ps脉冲基频光下，测得其粉末的倍频光强度为尿素的1.8倍有 很好的透明性（最长波长吸收峰位于322nm）和较好的热稳定性（熔点为225-227℃ ）     

Na6MQ4 (M=Zn,Cd; Q=S,Se): Promising New Ternary Infrared Nonlinear Optical Materials

Four sodium-based ternary IR nonlinear optical (NLO) materials, Na₆MQ₄ (M=Zn, Cd; Q=S, Se), were prepared through a high-temperature flux method. The crystal structure of the compounds is built up of isolated [MQ₄] tetrahedra and a 3D framework formed by the NaQ_n (n=4, 5) units. The two selenides, Na₆MSe₄ (M=Zn, Cd), as promising IR NLO materials, show moderate second-harmonic generation (SHG) responses (0.9 and 0.5×AgGaS₂) with good phase-matching behavior, as well as high laser damage thresholds (2 and 1.9×AgGaS₂). The two sulfides, Na₆MS₄ (M=Zn, Cd), exhibit higher laser damage thresholds (13 and 4×AgGaS₂), but smaller SHG responses (0.3 and 0.2×AgGaS₂). Theoretical calculations and statistical analyses indicate that the SHG effect and band gap in the compounds originate mainly from the distorted NaQ₄ NLO-active units with a short Na−S bond length, which provides a new insight into the design of novel IR NLO materials.     

Supramolecular polar thin films built by surfactant liquid crystals: polarization-tunable multilayer self-assemblies with in-plane ferroelectric ordering of ion-based dipoles.

Polar order in the phosphonium liquid crystal thin films, which are composed of two-dimensional ion-pair-based domains separated by the insulating hydrocarbon layers, was probed by second harmonic generation (SHG) analysis. Despite the ordinary amphiphilic self-assemblies containing no pi-electron moieties, the solid-state thin films retaining a smectic layer structure showed clearly an SHG activity, while the disordered films without the layer structure were not active at all for the SHG. It was found that the multilayer structure plays a crucial role for the SHG from the phosphonium thin films and the ionic layers act as an SHG-active site. The most significant characteristic of this system is to possess an ability to control SHG intensity electrically. The efficiency of the SHG process in the thin-film assemblies was enhanced by applying an external electric field parallel to the layer plane. Furthermore, through evaluation of thermal stability of the sample films, it was revealed that the SHG signals were detected only in the solid-state temperature range and the disappearance of the SHG occurs earlier than the solid-to-liquid crystalline phase transition. These results demonstrated that the origin of polar order in the phosphonium thin films is due to in-plane noncentrosymmetric arrangement (ferroelectric ordering) of ion pairs as an electric dipole, that is, dipole symmetry in an ionic layer.     

基于α,α-L-二芳基脯氨醇-吡啶衍生物的手性Ag(Ⅰ)配位聚合物:圆二色谱、二次谐波响应和发光性质（英文）

首次合成了α,α-L-二芳基脯氨醇-吡啶衍生物:S-二(4-(吡啶-4-基)苯基)(吡咯烷-2-基)甲醇(L),并用其与硝酸银自组装出具有梯形链结构的一维手性Ag(Ⅰ)配位聚合物{[Ag4(L)4](NO3)4·1.5CH3OH·1.25H2O}n(1);用IR、XRD、TG、粉末XRD和单晶XRD对聚合物结构进行了表征。圆二色谱和二次谐波响应测试也证明了它具有结构上的手性。此外,还研究了其荧光性质。