Second-harmonic generation studies of chiral organic salts

Article Abstract:

Second-harmonic generation (SHG) studies have been carried out on chiral organic salts addressing the requirement for solid-state asymmetry.. By far the majority of solids crystallize in centrosymmetric space groups making them SHG-inactive. The acid p-nitrophenylglycine was coupled to six optically pure amines to form salts and/or complexes that crystallized in non-centrosymmetric space groups, the result of the chiral counterion. From each of the salts the output from a Nd:YAG laser produced 532-nm second-harmonic generation. Three of the salts gave second-harmonic intensities at least an order of magnitude greater than that of the standard, urea. X-ray crystallographic analysis was carried out on five of the salts. On them an effort was made to rationalize the second-harmonic intensity based on orientation of molecular charge-transfer axis in the unit cell and on chromophore density.

Canada, Usage, Materials science, Organic compounds, Nonlinear optics, Enantiomers

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A new one-dimensional thriocyanato-bridged bimetallic compound (Cu(en)2Mn(NCS)4(H2O)2) sub n-): synthesis, crystal structure, and magnetic properties

Article Abstract:

A new one-dimensional thiocyanato-bridged bimetallic compound, Cu(en)2Mn(NCS)4(H2))2) sub n-, has been found and synthesized. Its structure has been established and is made up of one-dimensional chains with alternating Mn(II) and Cu(II) ions bridged by NCS ligands. The coordination environment is elongated octahedral for Cu(II) and octahedral for Mn(II). Use of magnetic susceptibility measurements showed the compound to have a ground state of low-spin multiplicity. Comparison of theoretical and experimental findings has been made using a one-dimensional model, taking into account the zero field splitting effect.

Coordination compounds, Organometallic compounds, Nitrogen compounds, Copper compounds

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Iodine charge-transfer salts of bis(1,2,3,5-diselenadiazolyl) diradicals; solid-state characterization of the thiophene-bridged derivative ((Se2N2C)C4H2S(CN2Se2))(I)

Article Abstract:

The crystal structure of a charge-transfer salt has been determined by single-crystal X-ray diffraction. Electroreduction of a 2,5-thiophene-bridged, bis(1,2,3,5-diselenadiazolylium) salt, (T-2,5-Se)(SbF6)2, in acetonitrile with iodine and a Pt wire results in a very conductive 1:1 charge-transfer (CT) salt. The structure is comprised of precisely superimposed pi-stacks. In the stacks molecular units are bridged by columns of iodine atoms arranged in a disorderly fashion. Extended Huckel band-structure calculations are of interest relative to the transport properties and electronic structures.

Radicals (Chemistry), Charge transfer, Electron donor-acceptor complexes, Magnetic susceptibility

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