Claus G. Lugmair

Optimization of TNT sensory polymers

Our group has been involved in the design and synthesis of ultra-sensitive fluorescence sensory materials for the detection of 2,4,6 trinitrotoluene (TNT) and 2,4 dinitrotoluene (DNT). These schemes make use of a novel energy migration mechanisms to amplify the fluorescence response and have led to systems capable of rapid detection of these analytes at sub part-per-billion levels. In an effort to optimize the amplification and specificity, we have examined the nature of energy migration in our polymers systems because it is inherent in achieving amplification. polarization measurements and energy transfer studies between polymers were conducted in order to evaluate and maximize energy migration and hence TNT sensory response. The correlation of photo physical properties with molecular structure guided the synthesis of novel polymers with more discriminant optical responses. These synthetic efforts have yielded a library of sensory polymers with varying sensitivities to different analytes.

Design of novel iptycene-containing fluorescent polymers for the detection of TNT

Spin cast films of iptycene-derived aryleneethynylene polymers were synthesized and examined for their ability to detect electron deficient aromatics such as 2,4,6- trinitrotoluene and 2,4-dinitrotoluene. These polymers display a fast, reversible fluorescent response to vapors form these analytes, with the fluorescence attenuation dependent on the time of exposure of the films to the vapors. The iptycene-derived polymers have high fluorescence quantum yields in the solid state and display greater spectroscopic stabilities to heating and solvents than similar polyphenyleneethynylene polymers that lack rigid iptycene functionalities. The syntheses of these polymers will be discussed, as will their photophysical properties and response to different analytes.

Synthesis and Reactivity of Ti(III) Tris(tert-butoxy)siloxy Complexes

Reaction of TiCl3(THF)3 with 3 equivalents of LiOSi(OtBu)3 produces the Ti(III) siloxide Ti[OSi(OtBu)3]3(THF)2 (1), and a 1:4 ratio of the same reagents gives {LiTi[OSi(OtBu)3]4}x. Upon heating to 95 °C, compound 1 converts via THF ring-opening to [(tBuO)3 SiO]3TiO(CH2)4Ti[OSi(OtBu)3]3. The pyridine adduct Ti[OSi(OtBu)3]3(pyr)2, and polymeric {Ti[OSi(OtBu)3]3(4,4’-bipyridine)}n, are also described. Electronic spectra for the Ti[OSi (OtBu)3]3L2 complexes indicate D3h symmetry, and similar results for the 4,4’-bipyridine adduct suggest a linear polymeric structure.