Polydiacetylenes (PDAs) are of great interest due to their π-conjugated backbone related properties, such as linear and nonlinear optical properties. As a consequence, design and preparation of PDAs assume enormous importance today. This review deals with one aspect of PDA, that is, design and preparation of the diacetylene monomers and their polymers, PDAs having conjugated side groups. The aim of such an investigation is to produce materials which exhibit large third-order nonlinear optical susceptibilities and which consequently, can be obtained in a form to be customised for optical devices.

Novel polydiacetylenes for optical materials: beyond the conventional polydiacetylenes

A heterogeneous catalyst, nanosized MCM-41-Pd, was used to catalyze the Sonogashira coupling of aryl and heteroaryl halides with terminal alkynes in the presence of CuI and triphenylphosphine. The coupling products were obtained in high yields using low Pd loadings to 0.01 mol%, and the nanosized MCM-41-Pd catalyst was recovered by centrifugation of the reaction solution and re-used in further runs without significant loss of reactivity.

Sonogashira Reaction of Aryl and Heteroaryl Halides with Terminal Alkynes Catalyzed by a Highly Efficient and Recyclable Nanosized MCM-41 Anchored Palladium Bipyridyl Complex

Novel polydiacetylenes (PDAs) bearing alkyl and phenyl substituents have been synthesized, for the first time, by solution polymerization using acyclic enediyne metathesis. The resulting polymers are soluble in common organic solvents and show distinct physical and photophysical properties both in solution and as thin films, caused by different steric and electronic effects from the side-groups. Bulk heterojunction solar cells employing these PDAs have been fabricated and evaluated.

Solution processable polydiacetylenes (PDAs) through acyclic enediyne metathesis polymerization

This chapter discusses Polydiacetylenes (PDAs), which constitute a class of conjugated polymers that continue to attract a significant amount of scientific attention PDAs can be formed in the solid state via a topochemical reaction mechanism in which product formation is dominated by the crystal structure of the monomer PDAs have significant optical absorptions in the visible range of the spectrum, which can frequently be altered in a controllable way, by application of prolonged irradiation, stress, temperature, specific solvents, and interactions with a substrate It displays high-to-very high nonlinear optical properties because of the extended length of the conjugated chain in these materials in combination with a small energy gap PDAs are well suited as one-dimensional conductors, and this has given rise to many investigations regarding the factors that influence this phenomenon Polymers from diacetylenes (DAs) can be formed in the solid state via a 1,4-topochemical polymerization reaction that usually yields an enyne-type structure

Chapter 4 – Polydiacetylenes

Poly(2,5-thienylene ethynylene) and related oligomers

Topochemical reactivity of some conjugated diacetylenes with πconjugating substituents upon exposure to γ-radiation, UV-visible radiation and upon thermal annealing is described. Few of the diacetylenes undergo solid state polymerization to provide corresponding polydiacetylenes. The reflectance spectra of the resultant polydiacetylenes showed significant backbone-sidegroup electron coupling. The third-order nonlinear susceptibility of two of the polydiacetylenes obtained were evaluated using Maker's fringe technique. The third-order nonlinear susceptibility, χ(3) value obtained for the two samples were in the order of 10−11 esu for the fully polymerized polydiacetylene films. These values are comparable to the values reported previously for PDAs with aromatic sidegroups.

Solid state polymerization of diacetylenes with π-conjugating substituents for third-order nonlinear optical properties

A convenient method for the preparation of thienylacetylnes

Recently, there has been hectic research activity in search of organic materials which show promising non-linear optical properties.1–5 Polydiacetylenes (PDAs) attracted special attention as a candidate material for third order non-linear optical properties (χ 3). This interest is due to the fact that PDAs show large third order non-linear optical susceptibility, with a fast response time. Additional supporting and important features of PDAs are that they can be obtained in single crystal form or LB films and it is possible to tune their optical properties through “Molecular and crystal engineering” through a variety of sidegroups.

Diacetylenes with Formally Conjugated Sidegroups : Precursors to Liquid Crystalline Polymers ?

A Convenient Method for the Preparation of Thienylacetylenes.

Solid state 1,4-addition polymerisation of crystalline disubstituted diacetylenes(DAs) is known to give crystalline polydiacetylenes(PDAs)1 which exhibit very interesting optical and electronic properte5 because of the extended conjugation of π-electrons along the backbone2,3. The high and fast third order nonlinear optical response (x 3) shown by PDAs projects them as alternate materials for potential applications in electro-optics and all optical communication4 system in place of conventional inorganic materials. Efforts are being made to enhance the polarizability and conjugation along the PDA backbone to get enhanced x 3 response as it is related to the π -conjugation of the system.

Lalita P. Bhagwat

Papers

Solid state polymerization of diacetylenes with π-conjugating substituents for third-order nonlinear optical properties

A convenient method for the preparation of thienylacetylnes

Diacetylenes with Formally Conjugated Sidegroups : Precursors to Liquid Crystalline Polymers ?

A Convenient Method for the Preparation of Thienylacetylenes.

Optical Properties of Polydiacetylenes with π -Conjugating Substituents in Solution and Solid State