Zeolites as hosts for novel optical and electronic materials

A review of the use of zeolites as hosts for electronically active guest materials is presented. Metal, semiconductor and conductive polymer nanoparticles as electronic and optical material composites are reported with special emphasis on their synthesis.     

Photorefractive polymer composites based on nanosized nonlinear optical chromophores

Photorefractive (PR) polymer composites based on polymers with a high glass transition temperature in which the random distribution of a photosensitizer and a nonlinear optical chromophore as dopants is “frozen” were designed. In the case of the random distribution of chromophores, only the third-order electric susceptibility has a nonzero value. Therefore, nanosized structures having high third-order polarizability due to an extended conjugated-bond system (or cooperative electronic excitation) were used as nonlinear chromophores. Good PR characteristics are displayed by polymeric composites containing nanosized structures, such as cyanine dye J aggregates, supramolecular assemblies of ruthenium(II) complexes, and single-wall carbon nanotubes. The use of extended nanosized chromophores as simultaneous spectral sensitizers allowed polymer composites with PR sensitivity in the near IR region at 1064 and 1550 nm to be designed.     

Photochemical stability of nonlinear optical chromophores in polymeric and crystalline materials

We compare the photochemical stability of the nonlinear optical chromophore configurationally locked polyene 2-{3-[2-(4-dimethylaminophenyl)vinyl]-5,5-dimethylcyclohex-2-enylidene} malononitrile (DAT2) embedded in a polymeric matrix and in a single-crystalline configuration. The results show that, under resonant light excitations, the polymeric compound degrades through an indirect process, while the DAT2 crystal follows a slow direct process. We show that chromophores in a crystalline environment exhibit three orders of magnitude better photostability as compared to guest-host polymer composites.     

A host-guest optical sensor for aliphatic amines based on lipophilic cyclodextrin

A host-guest optical sensor for the determination of aliphatic amines as exemplified by octylamine is proposed. It is based on the reversible fluorescence enhancement of heptakis(2,6-di-O-isobutyl)-β-cyclodextrin(DOB-β-CD) hosting tetraphenylporphyrin (TPP) immobilized in poly(vinyl chloride) (PVC) membrane by aliphatic amine extracted from aqueous phase into membrane phase. The optimum membrane contained 1.15 wt % TPP, 6.15 wt % DOB-β-CD as sensing reagent and other membrane materials. The fluorescence enhancement of the membrane resulted from the formation of a stable three-component complex among DOB-β-CD, TPP, and aliphatic amines. With the optimum conditions described, the fluorescence response of the sensor to octylamine shows a good correlation with the theoretically derived equation in the range 1.0 × 10^–6 to 8.0 × 10^–4 mol/L. The response characteristics including reversibility, response time, reproducibility and lifetime and selectivity of this optical device are also discussed in detail. This sensor has also been applied for the determination of octylamine in water samples containing interferents with satisfactory recovery. Received: 21 November 1999 / Revised: 10 January 2000 / Accepted: 15 January 2000     

A host-guest optical sensor for aliphatic amines based on lipophilic cyclodextrin

A host-guest optical sensor for the determination of aliphatic amines as exemplified by octylamine is proposed. It is based on the reversible fluorescence enhancement of heptakis(2,6-di-O-isobutyl)-β-cyclodextrin(DOB-β-CD) hosting tetraphenylporphyrin (TPP) immobilized in poly(vinyl chloride) (PVC) membrane by aliphatic amine extracted from aqueous phase into membrane phase. The optimum membrane contained 1.15 wt % TPP, 6.15 wt % DOB-β-CD as sensing reagent and other membrane materials. The fluorescence enhancement of the membrane resulted from the formation of a stable three-component complex among DOB-β-CD, TPP, and aliphatic amines. With the optimum conditions described, the fluorescence response of the sensor to octylamine shows a good correlation with the theoretically derived equation in the range 1.0 × 10^–6 to 8.0 × 10^–4 mol/L. The response characteristics including reversibility, response time, reproducibility and lifetime and selectivity of this optical device are also discussed in detail. This sensor has also been applied for the determination of octylamine in water samples containing interferents with satisfactory recovery.     

A novel nonlinear optical crystal for the IR region: noncentrosymmetrically crystalline CsCdBr3 and its properties

A noncentrosymmetric crystal structure of CsCdBr(3) has been successfully observed with X-ray single-crystal structure analysis. It crystallizes in the hexagonal space group P6(3)mc, with a = 7.7281(14) A, b = 7.7281(14) A, c = 6.742(2) A, alpha = 90 degrees, beta = 90 degrees, gamma = 120 degrees, Z = 2. It was obtained by a new preparation procedure different from that reported in the literature that gave a centrosymmetric structure. The structure contains Cd-Br octahedrons, which are connected in a plane-sharing way to form one-dimensional long chains. Each octahedron is slightly distorted, as the three Cd-Br bond lengths are 2.774 A, while the other three Cd-Br bond lengths are 2.804 A. The distortion directions of all of the octahedrons are almost parallel and give rise to the accumulation of the microcosmic nonlinear optical (NLO) coefficient. The Kurtz powder technique shows that CsCdBr(3) has a powder second harmonic generation of about 2 times as large as that of potassium dihydrogen phosphate (KDP). It shows excellent transparency in the visible and infrared regions. The thermal stability is also good. Therefore it may be utilized as a potential nonlinear optical crystal for the IR region.     

Nanosized composites of synthetic zeolites and silver iodide as potentially electrochemically active materials

Zeolitic composite materials made up of silver iodide and potassium form of synthetic zeolites ZSM5 were prepared in different conditions. The composites were characterized by X-ray powder diffraction methods and their electrochemical properties were studied by conductivity measurements. The attention was focused on the composites of synthetic zeolite of ZSM5 and AgI prepared by treating a silver form of synthetic zeolite ZSM5 (Ag-ZSM5) with potassium iodide solution. On the basis of the ac conductivity data it has been inferred that AgI forms a thin conductive crystalline shell on the surface of the K-ZSM5 particles. The sharp conductivity change between 142 and 147 °C is due to AgI undergoing a phase transition from hexagonal to cubic symmetry at 146 °C. The electrochemical properties of the composites depend on the mode of preparation and on the subsequent thermal treatments.     

The synthesis of bis(oligophenyleneethynylenes): novel potential nonlinear optical materials

Various functionalised phenyleneethynylene dimers 10 and trimers 12 were synthesised by palladium-catalyzed Sonogashira methodology. These dimers and trimers were coupled to 1,8-diido-10-methoxyanthracene to generate bis(oligophenyleneethynylenes) 17 and 18. Preliminary results towards the construction of both phenyleneethynylene and phenylenevinylene hybrid motifs are presented.     

Organic monomeric glasses: A novel class of materials

An amorphous monomeric glass is defined as a mixture of compatible organic monomeric molecules with an infinitely low crystallization rate under the most favorable conditions. These mixtures can be formed in a one-part reaction of a multifunctional nucleus with a mixture of substituents. The “noncrystallizability” of the mixture is controlled by the structural dissymmetry of the nucleus and/or the substituents and the number of components making up the mixture. We have developed an equation to calculate the number of components in a given mixture, knowing the structure and functionality of the nucleus and the number of substituents. An HPLC characterization method was developed and used to investigate the effects of various reaction conditions on the component concentration distributions and physical properties of the resulting materials. A dissymmetry number defined as the total weight percent of odd-substituted components is believed to be a potential measure of the “noncrystallizability” of the mixture. Physical properties such as glass-transition temperature can be dramatically increased through controlled oligomerization at the price of a moderate increase in melt viscosity. The organic monomeric glasses, like amorphous polymers, have good film-forming properties. However, unlike polymers, they display extremely low melt-viscosities and large positive entropy-of-mixing values and can be ground easily into extremely small particles. These properties make them ideal for certain applications where compatibility, melt-flow, and small particle size are important.     

Combinatorial parallel synthesis and automated screening of a novel class of liquid crystalline materials

Combinatorial parallel synthesis has led to the rapid generation of a single-compound library of novel fluorinated quaterphenyls. Subsequent automated screening revealed liquid crystalline (LC) behaviour and gave qualitative relationships of molecular structures and solid state properties.     

Novel nanocomposite materials based on mesomorphic glasses of metal alkanoates: structure and nonlinear optical properties

Novel nanocomposite materials based on an ordered mesomorphic glass of metal alkanoates have been proposed for fast transfer and processing of optical information. Metal alkanoate salts when heated form a smectic mesophase which can be easily supercooled forming an ordered mesomorphic glass at room temperature. The glass has the structure of the smectic-A phase: electrostatic cation-anion layers alternate with bilayers of alkane chains. The mesomorphic glass is a universal matrix for organic and inorganic nanoinclusions and nanosized crystals. In this paper, the structure of the cells of the mesomorphic glasses with various inclusions and their nonlinear optical properties, which become evident upon the impact of pulsed laser radiation with an intensity of up to 5.5 MW/cm², have been investigated.     

Complex coordinated functional groups: A great genes for nonlinear optical materials

Complex coordinated functional groups [MA_xB_y]（M = Central coordination element; A, B = P, O, S, Se,F, Cl, Br or I） are composed of different types of anions A, B jointly linked to the same central cation M,which are in high potential to tune the physical properties of materials, e.g., second-order susceptibility,energy gaps and birefringence. Recently, Compound containing complex coordinated functional groups have attracted great attention in the nonlinear optical（NLO） fiel...     

Site-selective multi-emitter gold-silver metallopolymers: A novel class of self-assembled materials

New luminescent heterometallopolymers [(Au-C₆F₅)_m(AgOSO₂CF₃)_n (PVP)] with different Au:Ag molar ratios were synthesized. The luminescent emissions of these polymers are strongly dependent on the temperature, excitation wavelengths, and the Au(I):Ag(I) molar ratio. The incorporation of a precise amount of Ag(I) atoms in the backbone of [(Au-C₆F₅)_m(PVP)] metallopolymer allows a controlled tuning of the emission energy in the green-blue range.     

Intercalation assembly of optical hybrid materials based on layered terbium hydroxide hosts and organic sensitizer anions guests

Optical hybrid materials based on inorganic hosts and organic sensitizer guests hold promise for a virtually unlimited number of applications.In particular,the interaction and the combination of the properties of a defined inorganic matrix and a specific sensitizer could lead to synergistic effects in luminescence enhancing and tuning.The current article focuses on the intercalation assembly of optical hybrid materials based on the layered terbium hydroxide(LTbH) hosts and organic divalent carboxylic sensitizer anion guests by a hydrothermal process.The studies on the interactions between hosts and guests indicate that the type and arrangement of organic guests in the layer spacing of the LTbH hosts can make a difference in the luminescence of the hybrid inorganic-organic materials.     

1-苯甲酰基-3-取代苯基硫脲的合成及其倍频性能

自 1 986年Ｈ .Ａｂｅｒ-Ｈａｌｉｍ[1 ] 等首次对含硫有机化合物进行有机非线性光学性能研究以来 ,含硫有机化合物的倍频性能越来越受人们的重视。尿素是脲类化合物中发现较早的一种有机非线性光学材料 ,它的分子非线性系数低、易吸湿但它的透光性能好 ,透明区一直延伸到紫外区 ,并且具有很高的抗光伤阈值 ,可实现位相匹配 ,已成功应用于频率转换及其它方面。 1 -苯甲酰基 - 3-取代苯基硫脲 ,由于其不对称性强 ,引起吸收波段位移小 ,理论上符合ＮＬＯ分子设计要求。1　实验部分1 1　计算分子的ＮＬＯ性能是由分子的偶极距或生成热求导计算…     

Metal oxyhalides: an emerging family of nonlinear optical materials

Second-order nonlinear optical (NLO) materials have drawn enormous academic and technological attention attributable to their indispensable role in laser frequency conversion and other greatly facilitated applications. The exploration of new NLO materials with high performances thus has long been an intriguing research field for chemists and material scientists. However, an ideal NLO material should simultaneously satisfy quite a few fundamental yet rigorous criteria including a noncentrosymmetric structure, large NLO coefficients, desired transparent range, large birefringence, high laser damage threshold, and availability of a large-size single crystal. Therefore, the identification of promising compound systems, targeted design, and experience-based syntheses are crucial to discover novel NLO materials working in the spectral region of interest. As an important family of mixed-anion compounds, versatile metal oxyhalides containing metal-centered oxyhalide functional units ([MO_mX_n] (X = F, Cl, Br, and I)) are becoming a marvelous branch for interesting NLO materials. Especially, when the central metals are d⁰/d¹⁰ transition metals or heavy post-transition metals, a number of novel NLO materials with superior functionalities are expected. Our thorough review on the recent achievements of metal oxyhalides for NLO materials are divided into the fast-growing NLO metal oxyhalides with single type halogen anions and the newly identified NLO metal oxyhalides with mixed halogen anions. Here we mainly focus on the design strategy, structural chemistry, NLO-related properties, and structure–property correlation of the metal oxyhalides with relatively large NLO responses. We hope this review can provide an insight on the rational design and future development of emerging metal oxyhalides for NLO and other applications.

Nonlinear optical metal oxyhalides could provide a new insight into the target design and exploratory synthesis of new functional materials with intriguing chemical and physical properties.     

Thermal analysis of composites based on crystalline polymers and metals

Differential scanning calorimetry (DSC), thermogravimetric analysis (TG) and infrared (IR) spectroscopy have been used to examine the chemical and physical changes (crystallinity, accumulation of oxygen-containing groups, etc.) during thermal oxidation of polyethylene, polypropylene and Penton contained in coatings and metalfilled films, taking into account the thickness of the polymer layer and catalytic activity of the metal.

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Zusammenfassung DSC, thermogravimetrische Analyse (TG) und infrarot (IR) Spektroskopie wurden zur Untersuchung der während der thermischen Oxidation von in Belägen und metallgefüllten Filmen enthaltenem Polyäthylen, Polypropylen und Penton stattfindenden chemischen und physikalischen Veränderungen (Kristallinität, Anhäufung stickstoffhaltiger Gruppen usw.) eingesetzt. Hierbei wurden die Stärke der Polymerschicht und die katalytische Aktivität des Metalls in Betracht genommen.

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Multicomponent host-guest chemistry of carboxylic acid and phosphonic acid based guests with dendritic hosts: an NMR study

A new way to analyze supramolecular dendritic architectures is reported by making use of (13)C NMR and (31)P NMR. Two ethylene glycol guest molecules have been synthesized containing a (13)C labeled carboxylic acid headgroup (2) and a phosphonic acid headgroup (3). The binding of these guests to urea-adamantyl modified poly(propylene imine) dendrimers has been investigated with (13)C NMR and (31)P NMR next to 1D and 2D (1)H NMR techniques. Different amounts of guest 2 have been added to fifth generation dendrimer 1e, and the observed chemical shift values in (13)C NMR were fitted to a model that assumes 1:1 binding between guest and binding site. An association constant of 400 +/- 95 M(-)(1) is obtained for guest 2 with 41 binding sites per dendrimer. When different amounts of phosphonic acid guest 3 are added to dendrimer 1e, two different signals are observed in (31)P NMR. Deconvolution gives the fractions of free and bound guest, resulting in an association constant of (4 +/- 3) x 10(4) M(-)(1) and 61 +/- 1 binding sites. A statistical analysis shows that guest 2 forms a "polydisperse supramolecular aggregate", while guest 3 is able to form a "monodisperse supramolecular aggregate" when the amount of guest is high enough. The NMR results are compared with dynamic light scattering experiments, and a remarkable agreement is found. Phosphonic acid guest 3 is able to exchange with guest 2, which is in agreement with the obtained association constants, and shows that these techniques can be used to analyze multicomponent dendritic aggregates.