Highly Efficient and Thermally Stable Second-Order Nonlinear Optical Chromophores and Electrooptic Polymers

Organic polymeric electro-optic (E-O) materials have attracted significant attention because of their potential use as fast and efficient components of integrated photonic devices (1,2). However, the practical application of these materials in optical devices is somewhat limited by the stringent material requirements imposed by the device design, fabrication processes and operating environments. Among the various material requirements, the most notable ones are large electro-optic coefficients (r(33)) and high thermal stability (3). The design of poled polymeric materials with high electro-optic activity (r(33)) involves the optimization of the percent incorporation of efficient (large beta mu) second order nonlinear optical (NLO) chromophores into the polymer matrices and the effective creation of poling-induced non-centrosymmetric structures. The factors that affect the material stability are a) the inherent thermal stability of the NLO chromophores, b) the chemical stability of the NLO chromophores during the polymer processing conditions, and c) the long-term dipolar alignment stability at high temperatures. Although considerable progress has been made in achieving these properties (4), organic polymeric materials suitable for practical E-O device applications are yet to be developed. This chapter highlights some of our approaches in the optimization of molecular and material nonlinear optical and thermal properties.

Highly luminescent and thermally stable lanthanide coordination polymers designed from 4-(dipyridin-2-yl)aminobenzoate: efficient energy transfer from Tb3+ to Eu3+ in a mixed lanthanide coordination compound

Herein, a new aromatic carboxylate ligand, namely, 4-(dipyridin-2-yl)aminobenzoic acid (HL), has been designed and employed for the construction of a series of lanthanide complexes (Eu3+ = 1, Tb3+ = 2, and Gd3+ = 3). Complexes of 1 and 2 were structurally authenticated by single-crystal X-ray diffraction and were found to exist as infinite 1D coordination polymers with the general formulas {Eu(L)(3)(H2O)(2)]}(n) (1) and {Tb(L)(3)(H2O)]center dot(H2O)}(n) (2). Both compounds crystallize in monoclinic space group C2/c. The photophysical properties demonstrated that the developed 4-(dipyridin-2-yl)aminobenzoate ligand is well suited for the sensitization of Tb3+ emission (Phi(overall) = 64%) thanks to the favorable position of the triplet state ((3)pi pi*) of the ligand the energy difference between the triplet state of the ligand and the excited state of Tb3+ (Delta E) = (3)pi pi* - D-5(4) = 3197 cm(-1)], as investigated in the Gd3+ complex. On the other hand, the corresponding Eu3+ complex shows weak luminescence efficiency (Phi(overall) = 7%) due to poor matching of the triplet state of the ligand with that of the emissive excited states of the metal ion (Delta E = (3)pi pi* - D-5(0) = 6447 cm(-1)). Furthermore, in the present work, a mixed lanthanide system featuring Eu3+ and Tb3+ ions with the general formula {Eu0.5Tb0.5(L)(3)(H2O)(2)]}(n) (4) was also synthesized, and the luminescent properties were evaluated and compared with those of the analogous single-lanthanide-ion systems (1 and 2). The lifetime measurements for 4 strongly support the premise that efficient energy transfer occurs between Tb3+ and Eu3+ in a mixed lanthanide system (eta = 86%).

A cocktail of thermally stable, chemically synthesized capture agents for the efficient detection of anti-gp41 antibodies from human sera and techniques

This thesis reports on a method to improve in vitro diagnostic assays that detect immune response, with specific application to HIV-1. The inherent polyclonal diversity of the humoral immune response was addressed by using sequential in situ click chemistry to develop a cocktail of peptide-based capture agents, the components of which were raised against different, representative anti-HIV antibodies that bind to a conserved epitope of the HIV-1 envelope protein gp41. The cocktail was used to detect anti-HIV-1 antibodies from a panel of sera collected from HIV-positive patients, with improved signal-to-noise ratio relative to the gold standard commercial recombinant protein antigen. The capture agents were stable when stored as a powder for two months at temperatures close to 60°C.

Thermally stable chromophores for nonlinear optical applications

Three thermal organic second-order nonlinear optical chromophores were synthesized. The decomposition temperature was determined by DSC, and the absorption spectra was measured. The second-order polarizabilities at zero energy and the dispersion of second-order polarizabilities were measured by solvatochromic method. (C) 2002 Elsevier Science Ltd. All rights reserved.

Thermally Stable Guest-Host Polyetherketone Poled Polymer for Electro-Optical Applications

The high glass transition temperature polymer polyetherketone doped with disperse red 13 (DR13/PEK-c) has been prepared by the spin-coating method. Through in situ second-harmonic generation, the corona poling temperature was optimized by measuring the temperature dependence of the in situ second-harmonic generation signal intensity under the poling electric field. The linear electro-optic coefficients of the poled polymer films have been determined at 632.8 nm by using a simple interferometric technique. The polymer system was measured after 13 000 h, and found that it remained at 80% of its initial value.

Bright green organic electroluminescent devices based on a novel thermally stable terbium complex

A navel thermally stable terbium carboxylate complex, Tb(MTP)(3)(phen) (MTP=monotetradecyl phthalate, phen=1,10-phehanthroline), was synthesized and characterized. The device structure of glass substrate/indium-tin-oxide/poly(p-phenylenevinylene) (PPV)/poly (N-vinycarbazole) (PVK):Tb(MTP)(3)(phen): 1,3,4-oxadizole derivative (PBD)/tris(8-hydroxyquinoline) (Alq(3))/aluminum (Al) was employed to study the electroluminescent properties of Tb(MTP)(3)(phen). A green emission with extremely sharp spectral band of less than 10 nm at 544 nm peak wavelength was observed. A maximum luminance of 152 cd/m(2) and an external quantum efficiency of 0.017% were achieved at a drive voltage of 24 V. A possible mechanism of energy transfer based on the polymer doped with lanthanide organic complex was also proposed.

Thermally stable interpenetrating polymer networks for second-order nonlinear optical materials

We report several kinds of interpenetrating polymer networks (IPNs) with nonlinear optical (NLO) properties. DMA spectra show that the two components of the IPNs have good compatibility with each other. The NLO materials have good optical transparency. The thermal stability of alignment was improved and the poled order remained very high. (C) 1999 John Wiley & Sons, Inc.

High-surface thermally stable mesoporous gallium phosphates constituted by nanoparticles as primary building blocks

In constant, search for micro/mesoporous materials, gallium phosphates, have attracted continued interest due to the large pore size reported for some of these solids in comparison with analogous aluminum phosphates. However up to now, the porosity of gallium phosphates collapsed upon template removal or exposure to the ambient moisture. In the present work, we describe high-surface thermally stable mesoporous gallium phosphates synthesized from gallium propoxide and PCl3 and different templating agents such as amines (dipropylamine, piperidine and aminopiperidine) and quaternary ammonium salts (C16H33(CH3)3NBr and C16PyCl). These highly reactive precursors have so far not been used as gallium and phosphate sources for the synthesis of gallophosphates. Conceptually, our present synthetic procedure is based on the fast formation of gallium phosphate nanoparticles via the reaction of gallium propoxide with PCl3 and subsequent construction of the porous material with nanoparticles as building blocks. The organization of the gallophosphate nanoparticles in stable porous structures is effected by the templates. Different experimental procedures varying the molar composition of the sol-gel, pH and the pretreatment of gallium precursor were assayed, most of them leading to satisfactory materials in terms of thermal stability and porosity. In this way, a series of gallium phosphates with surface are above 200 m(2) g(-1), and narrow pore size from 3 to 6 nm and remarkable thermal stability (up to 550 degrees C) have been prepared. In some cases, the structure tends to show some periodicity and regularity as determined by XRD. The remarkable stability has allowed us to test the catalytic activity of gallophosphates for the aerobic oxidation of alkylaromatics with notable good results. Our report reopens the interest for gallophosphates in heterogeneous catalysis. (C) 2010 Elsevier Inc. All rights reserved.

Development of thermally stable versions of the Burgess Reagent : approaches to the chemoenzymatic total synthesis of morphine

The present studies describe our recent work on expanding the use of the Burgess reagent and its reaction with oxiranes. Several new variants of the Burgess reagent and its chiral auxiliary version were evaluated for their thermal stability by NMR spectroscopy. Three new versions of the reagent were synthesized and their stability was determined. The reactivity of all five Burgess reagents was compared in a dehydration reaction and reactions with epoxides and diols. Progress toward a chemoenzymatic synthesis of morphine is also included in this report. The synthesis began with the whole cell oxidation of bromobenzene by Escherichia coli JMI09(pDTG601). The preparation of several precursors for a key step involving the lohnson-Claisen rearrangement and progress toward the total synthesis are described.

Synthesis and characterization of thermally stable second-order nonlinear optical side-chain polyimides containing thiazole and benzothiazole push-pull chromophores

Push-pull nonlinear optical (NLO) chromophores containing thiazole and benzothiazole acceptors were synthesized and characterized. Using these chromophores a series of second-order NLO polyimides were Successfully prepared from 4,4'-(hexafluoroisopropylidene) diphthalic anhydride (6FDA), pyromellitic dianhydride (PMDA) and 3,3'4,4'-benzophenone tetracarboxylic dianhydride (BTDA) by a standard condensation polymerization technique. These polyimides exhibit high glass transition temperatures ranging from 160 to 188 degrees C. UV-vis spectrum of polyimide exhibited a slight blue shift and decreases in absorption due to birefringence. From the order parameters, it was found that chromophores were aligned effectively. Using in situ poling and temperature ramping technique, the optical temperatures for corona poling were obtained. It was found that the optimal temperatures of polyimides approach their glass transition temperatures. These polyimides demonstrate relatively large d(33) values range between 35.15 and 45.20 pm/V at 532 nm. (C) 2008 Elsevier B.V. All rights reserved.

A thermally stable tension meter for atmospheric soundings using kites

Kites offer considerable potential as wind speed sensors—a role distinct from their traditional use as instrument-carrying platforms. In the sensor role, wind speed is measured by kite-line tension. A kite tether line tension meter is described here, using strain gauges mounted on an aluminum ring in a Wheatstone bridge electronic circuit. It exhibits a linear response to tension 19.5 mV N−1 with good thermal stability mean drift of −0.18 N °C−1 over 5–45 °C temperature range and a rapid time response 0.2 s or better. Field comparisons of tether line tension for a Rokkaku kite with a fixed tower sonic anemometer show an approximately linear tension-wind speed relationship over the range 1–6 ms−1. © 2010 American Institute of Physics. doi:10.1063/1.3465560