Study of the kinetics of ortho-substituted phenylnitrenes and their reactions with pyridine containing polymers

Laser flash photolysis (LFP) of various substituted phenyl azides produces the corresponding singlet nitrenes, which were detected by their transient absorptions. The rate of decay of these singlet nitrenes were obtained as a function of temperature to determine the rate of intersystem crossing (k_isc) to the triplet nitrenes, the activation energy (E_a) for the two step ring expansion to the ketenimine through an azirine intermediate, and the logarithm of the preexponential factor (log A). We found that substituents in the para position to the nitrene have little effect on E_a and the lifetime of the singlet nitrene. Adding one methyl substituent at the ortho position also has no effect on E_a or the singlet nitrene lifetime. Adding a second methyl group at the other ortho position raises E_a by about 2 kcal/mol over the parent system, as well as increasing the singlet nitrene lifetime form 1 ns to 12 ns at ambient temperature.; Three materials were designed and synthesized that are capable of accepting energy from the triplet excitons and emitting from the triplet state at room temperature. These materials also contain multiple perfluorinated phenyl azide functionalities, which can be photolyzed to produce the corresponding phenyl nitrenes. Also, several conducting polymers were designed and synthesized that contain pyridine groups in the main polymer chain and in side chains. The nitrenes were shown to react with CH bonds of polystyrene and pyridine groups of the conducting polymers, as shown by preparative gel permeation chromatography. The porphyrin azide Pt-TFPP-Az was shown to react with pyridine-containing polymers with a high efficiency, while the organometallic azide Ru-bipy-Az reacted with very low efficiencies.; We present the first study of chirality from the ultraviolet to the infrared region for a conducting polymer, thereby probing the motion of the metallic “free carriers.” Through study of chiral and achiral camphorsulfonic acid (CSA) doped polyaniline (PAN) films cast from different solvents ( m-cresol and chloroform) and correlations with secondary doping experiments, we demonstrate that the chirality lies in the order “metallic” regions of the polymer films. The metallic films (cast from m-cresol) show strong optical activity of the conducting electrons in the visible and infrared regions, showing that a chiral metal can be prepared by the methods of organic chemistry. (Abstract shortened by UMI.)...