Synthesis, photophysical, electrochemical, and structural engineering of (porphinato)zinc(II) ethynylenes for electrical materials applications.

摘要

This thesis focuses on the design, synthesis, spectroscopy, electrochemical, and structural properties of (porphinato)zinc(II) ethynylenes (oligomers and polymers). Such compounds are of interest for electrical and optical materials applications.;Previous (porphinato)zinc(II) meso-to-meso ethynyl bridged oligomers (PZnn) that featured phenyl substituents suffered from solubility issues that hindered the synthesis of larger arrays. Modification of the peripheral phenyl group with butyloxy or PEG side chains at the 3,5 and 2,6 positions has allowed the construction of soluble dimer, trimer, pentamer, and up to heptamer ethynyl bridged arrays. These soluble derivatives were synthesized through the use of Pd catalyzed cross-coupling reactions and were easily isolated and characterized by various chromatographic methods. It was found that upon extension of the oligomer series there is an optical and potentiomeric band gap reduction, which is demonstrative of the delocalized nature of the porphyrinic π-system.;The Sonogashira Pd catalyzed cross-coupling reaction was investigated to construct PZnnO3Hex and donor-acceptor polymers bearing alternating PZnO3Hex and 10,20-bis(heptafluoropropyl)porphinato)zinc(II) repeat units, PZnO3Hex(C3F7)polymers. PZnnOHex and PZnO3Hex(C3F 7) polymers were isolated from each reaction and then purified and characterized by electronic absorption spectroscopy, GPC, MALD1-TOF, 1H and 13C NMR, and thin film cyclic voltammetry.;X-band Electron Spin Resonance (ESR) spectroscopic data for the cation radical states of PZnn oligomers has been measured. These [PZnn]+ (n=2-7) species span an average 18-75 Å length scale and display peak-to-peak EPR line widths (ΔBp-p) that diminish with conjugation length. Analysis of these EPR data show that [PZnn]+ structures possess the largest hole polaron delocalization lengths yet measured; experiments carried out over a 4-298 K temperature domain demonstrate remarkably that the charge delocalization length remains invariant with temperature.;We report dark conductivity (DC) measurements for a family of meso-to-meso ethyne-bridged (porphinato)zinc(II) (PZnn) oligomers that feature a wide range of peripheral ancillary substituents. Two- and four-probe DC data obtained for thin film and pressed pellet solid-state samples of undoped PZnn oligomers are mutually consistent, and underscore that the measured DCs for these low molecular weight oligomers span an impressively wide range (2 x 10-12 − 4 x 10-5 S/cm).