One-dimensional coordination polymers: applications to material science

Donor-acceptor polyenes of various lengths, and that combine aro- matic electron-donating moieties with powerful heterocyclic electron-withdraw- ing terminal groups, have been synthe- sized and characterized as efficient non- linear optical (NLO) chromophores. Their linear and nonlinear optical proper- ties have been investigated, and variations in these properties have been related to ground-state polarization (dipole p) and structure. In particular, unprecedented quadratic hyperpolarizabilities (p) have been achieved (up to p(0) =I500 x 10-30esu) by reduction of the bond- length alternation (BLA) in the polyenic chain. In each series of homologous com-

Large Quadratic Hyperpolarizabilities with Donor–Acceptor Polyenes Exhibiting Optimum Bond Length Alternation: Correlation Between Structure and Hyperpolarizability

Electro‐optic phase modulation was measured along with optical second‐harmonic generation in thin films of a new copolymer containing a dicyanovinyl‐terminated azo dye side chain Orientational order was imparted to these films by poling with a corona discharge Details of the electro‐optic measurement technique, in which the real part of the electro‐optic coefficient can be determined directly, are presented Taking advantage of the increased orientation imparted by corona poling and the hindered motion of the nonlinear optical moiety in the side chain of the polymer leads to substantial improvements in both the magnitude and stability of nonlinear optical susceptibilities compared to guest‐host polymer systems ordered by electrode poling

Electro-optic phase modulation and optical second-harmonic generation in corona-poled polymer films

A systematic study of the dependence of the band gap, the linear optical susceptibility, the polarizability α, and the second hyperpolarizability γ, on the number of repeat unit is conducted for the thiophene series from monomer to hexamer. The linear optical susceptibilities for oligomers have been determined from the refractive index measurements on vacuum deposited films using the m lines technique. The orientationally averaged polarizabilities 〈α〉 have been measured from refractive index measurements of THF solutions. The orientationally averaged second hyperpolarizabilities 〈γ〉 have been measured by degenerate four‐wave mixing studies of THF solutions. The validity of the Lorentz–Lorenz approximation is tested and found to be satisfactory. The experimental values of 〈α〉 and 〈γ〉 for thiophene and 〈α〉 for bithiophene are found to be in qualitative agreement with those obtained by a recent ab initio calculation which used the finite field method and included diffuse polarization functions. The experimentally observed dependence of 〈α〉 and 〈γ〉 on the number N of the thiophene repeat unit is compared with that predicted by a free electron model, PPP methods, and the ab initio calculations. For the case of polarizability, the repeat unit dependence is in good agreement with that predicted by the ab initio calculations but for the case of second hyperpolarizability, the agreement is not as good.

A systematic study of polarizability and microscopic third‐order optical nonlinearity in thiophene oligomers

Real-time monitoring of the corona-poling process that is used to create a bulk second-order nonlinear-optical susceptibility was accomplished by observing electrochromic shifts and intensity decreases of charge-transfer absorption bands in both dye-doped and covalently functionalized polymer films. By measuring small changes in the refractive-index anisotropy, the optical waveguiding technique was demonstrated to be a sensitive measure of the poling-induced order and its relaxation. The guest–host systems were formed from the dyes N,N-dimethylaminonitrostilbene, N,N-dimethylindoaniline (Phenol Blue), and 4-(N-(2-hydroxyethyl)-N-ethyl)-amino-4′-nitroazobenzene (Disperse Red 1), each dissolved in a poly(methyl methacrylate) matrix. The covalently functionalized polymers contained pendant para-nitroaniline (PNA) moieties. The first, poly(N-(4-nitrophenyl)allylamine), was formed from a poly(allylamine) derivative and is called PPNA. The second was based on poly(hydroxystyrene), with PNA attachment occurring between the phenol group and the PNA hydroxyethyl group; this polymer is named PHS-MENA. The final polymer is a linear epoxy (bisphenol A) with the PNA amino N atoms forming a link in the main chain; it is called Bis A-NA. A sample calculation demonstrated the use of experimental electrochromic spectral data to estimate the electro-optic coefficients.

Electrochromic and optical waveguide studies of corona-poled electro-optic polymer films

Nonlinear Optical and Electroactive Polymers: An Overview- Nonlinear Optical Polymers- Microscopic Origin of Second Order Nonlinear Optical Properties of Organic Structures- Design, Ultrastructure, and Dynamics of Nonlinear Optical Effects in Polymeric Thin Films- New Nonlinear Organic Crystals for Ultrafast Infra-Red Optical Processing- Electric-Field Poling of Nonlinear Optical Polymers- Frequency and Temperature Variations of Cubic Susceptibility in Polydiacetylesnes- Femtosecond Studies of Dephasing and Conjugation with Incoherent Light- Studies of Monomer and Polymer Monolayers Using Optical Second and Third Harmonic Generation- Development of Polymer Nonlinear Optical Materials- Orientationally Ordered Electro-Optic Materials- Conformation Transition in Polydiacetylene Solution- Molecular Engineering Approaches to Molecular and Macromolecular Nonlinear Optical Materials: Recent Theoretical and Exprimental Result- Poled Copoly(Vinylidene Flouride-Triflouroethylene) As A Host for Guest Nonlinear Optical Molecules- Electroactive Polymers- Electroactive Polymers:Consequences of Electron Delocalization- Optical Properties of Poly(p-Phenylene Vinylene)- Holes,Electrons,Polarons, and Bibpolarons and the Thermodynamics of electrically Active Dopants in Conduting Polymers- Transient Current Spectroscopy in Polymeric Films- Electrochemistry of Polyaniline:Consderation of a Dimer Model- Theory- A PPP Variational-Perturbation Calculating of Hyperplarizabilities of Conjudated Chains- Optical Spectra of Flexible Conjugated Polymers- Excitation in Conjugated Polymers- Synthesis- Towards New Electronic Structures in Crytallographically Ordered Conjugated Polymers- Side Chain Liquid Crystalline Copolymers for NLO Response- Synthesis of Certain Specific Electroactive Polymers- Rigid Aromatic Heterocyclic Polymers:Synthesis of Ploymers and Oligomers Containing Benzazole Units for Electrooptic Application- Devices- Nonlinear and Electro-Optic Organic Devices- Nonlinear and Optical processes in Optical Fibers- Nonlinear Optical Processes and Application in the Infrared with Nematic Liquid Crystals

Donald R. Ulrich

Papers

Nonlinear optical and electroactive polymers