Magnetic and Electric Properties of Organic Conductors Probed by 13C-NMR Using Selective-Site Substituted Molecules

Spectroscopic investigation of some building blocks of organic conductors: A comparative study

Theoretical molecular structures and IR and Raman spectra of di and tetra methyl substituted tetrathiafulvalene and tetraselenafulvalene molecules have been studied. These molecules belong to the organic conductor family and are immensely used as building blocks of several organic conducting devices. The Hartree-Fock and density functional theory with exchange functional B3LYP have been employed for computational purpose. We have also performed normal coordinate analysis to scale the theoretical frequencies and to calculate potential energy distributions for the conspicuous assignments. The exciting frequency and temperature dependent Raman spectra have also presented. Optimization results reveal that the sulphur derivatives possess boat shape while selenium derivatives possess planner structures. Natural bond orbitals analysis has also been performed to study second order interaction between donors and acceptors and to compute molecular orbital occupancy and energy.

Determination of the hyperfine coupling tensor in organic conductors κ-(BEDT-TTF)₂X (X=Cu[N(CN)₂]Br, Cu(NCS)₂) on central ¹³C sites

Although the organic superconductors κ-(BEDT-TTF)2X (X=Cu[N(CN)2]Br and Cu(NCS)2) have been studied by NMR spectroscopy, hyperfine coupling tensors are required to quantify NMR spectra. Angle dependences of NMR spectra were measured to determine hyperfine coupling tensors applicable to further NMR assessments of attractive physical phenomena on κ-salts. The tensors of κ-(BEDT-TTF)2X and β(')-(BEDT-TTF)2ICl2 salts were compared to determine the hyperfine coupling mechanism in organic metals, with the results indicating that off-site dimer contribution should be considered. We also report the electron correlation of these salts and further application of the tensors.