All ETDs from UAB

Advisory Committee Chair

Gary M Gray

Advisory Committee Members

Houston Byrd

Christopher M Lawson

Sadanandan E Velu

Charles L Watkins

Document Type

Dissertation

Date of Award

2011

Degree Name by School

Doctor of Philosophy (PhD) College of Arts and Sciences

Abstract

The synthesis and optical characterization of a series of novel molecular and polymeric phosphonate-substituted bithiophenes are reported. Many of the compounds reported herein exhibit good nonlinear optical absorption and emission properties in the violet-blue spectral region. The first chapter investigates a series of molecular phosphonate bithiophenes derived from 2,2′-biphenol, BpP(X)(C4H2S)2H and BpP(X)(C4H2S)2P(X)Bp (Bp = 2,2′-C12H8O2; X = O, S , Se). Their syntheses have been optimized, and solid-state structures of two of these compounds are reported. The linear absorption spectra, emission spectra, and emission quantum yields show distinct trends with respect to the chalcogen attached to the phosphorus and the number of phosphorus substituents attached to the 2,2′-bithiophene ring. Nonlinear transmission measurements indicate that solutions of the compounds show nonlinear absorption at 430 nm with 27-ps laser pulses in spite of their low solubilities in organic solvents. In the second chapter, the synthesis, linear absorption and emission spectra, and nonlinear absorptions at 430 nm of two new series of molecular phosphonate-substituted bithiophenes, pdP(X)(C4H2S)2H and pdP(X)(C4H2S)2P(X)pd (pd = OCH,sub>2C(CH3)2CH2O; X = O, S, Se), are reported. The X-ray crystal structures of four of these compounds have also been determined. Similar structure-optical property relationships are observed to those reported from Chapter 1. The nonlinear optical absorption of saturated solutions of two of these compounds is significantly improved relative to those of the phosphonates reported in the first chapter and rivals the best violet-blue nonlinear absorbers reported in the literature. In the last chapter, a method of incorporating phosphonate-functionalized 2,2′-bithiophenes into a polymer system was developed. The number average molecular weights of these polymers range from 1.1 to 4.3 x 104 Da. Thermal characterization indicates that all of the polymers are in the rubbery state at room temperature and have thermally stabilities as high as 290 ºC. The linear optical properties of the polyphosphonates are similar to those of previously reported nonlinear optical molecular phosphonates, yet are more soluble in organic solvents making them excellent candidates for violet-blue optical power limiting applications.

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