The work reported in this thesis uses Bayesian inference and density functional theory (DFT) to perform multifrequency Electron Paramagnetic Resonance (EPR) lineshape analysis on copper and nitroxide complexes.
We also report a development of a High Field (HF) EPR spectrometer at the UAlbany Laboratory and the success of site directed mutagenesis on genetically engineered polypeptide (YEHK14).
Experiments were performed at different frequencies (S, X, K, Q, and W Band) for model systems [copper acetyl acetonate (Cu(acac)2) and 5,10,15,20 - Tetraphenyl - 21H,23H -porphine copper(II) (CuTPP)] in toluene at different temperatures to understand their structure and dynamics. A new fitting program based on the methods of Bayesian Inference was developed to analyze simultaneously the multifrequency cw EPR spectra. Four different sets of model parameters used to describe cw EPR spectra for two different probe symmetries (axial and rhombic) were explored using a model for rotational diffusion that was analyzed via the stochastic Liouville equation. Simultaneous multifrequency fits have been successfully performed on S, X, K, Q, & W band EPR spectra of Cu(acac)2 and on S, X, K, & Q band EPR spectra of CuTPP. Differential entropy and channel capacity (with and without Wiener filter) were estimated to quantify the relative amount of spectral information available at each frequency.
An X band EPR study of N15 & mixture (N14/N 15) of Perdeuterated 2,2,6,6 –tetramethyl-4-piperidone N-oxide (PD-Tempone) on glycerol/water at different temperatures was performed to assess whether lineshape analysis of the mixture is a more informative experiment than the spectra from only one spin label isotope.
DFT calculations were performed to study the basis sets and functional dependence of magnetic tensor parameters for Cu(acac)2 and CuTPP. The estimated DFT values of g tensor and hyperfine tensor for Cu(acac)2 and CuTPP agree with experimental values from rigid limit spectra whereas the superhyperfine tensor agrees with experimental values from motionally narrowed spectra.
The principle of operation of the High Field (HF) EPR lab set up was verified by collecting the first HF EPR spectra at UAlbany of 2,2-Diphenyl-1-Picrylhydrazyl (DPPH) at 160 GHz
We also describe the procedure for performing site directed mutagenesis on YEHK14.