Molecular crystals, magnetism

The room temperature electrical conductivity of single crystals of M03S7 (dmit)3 along the c axis is 25 S cm, which is very high for a neutral molecular crystal. The variation of the magnetic susceptility (/) with the temperature does not follow a Curie-Weis law with a continuous decrease of /T vs. Tupon cooling... 

Assemblies of molecules are most often found in molecular crystals with very weak interactions between the molecular entities. They can also be found in extended systems, built from molecular or ion-radical precursors, in a way that maximizes the interactions between the precursors and, hopefully, yields bulk magnetic properties. 

An interesting aspect of many structural phase transitions is the coupling of the primary order parameter to a secondary order parameter. In transitions of molecular crystals, the order parameter is coupled with reorientational or libration modes. In Jahn-Teller as well as ferroelastic transitions, an optical phonon or an electronic excitation is coupled with strain (acoustic phonon). In antiferrodistortive transitions, a zone-boundary phonon (primary order parameter) can induce spontaneous polarization (secondary order parameter). Magnetic resonance and vibrational spectroscopic methods provide valuable information on static as well as dynamic processes occurring during a transition (Owens et ai, 1979 Iqbal Owens, 1984 Rao, 1993). Complementary information is provided by diffraction methods. 

Dithiolenes have been the subject of numerous studies relating to their ability to conduct electric currents and to show unusual magnetic properties. Both are consequences of extended inter-molecular interactions in molecular crystals of such order that the overlap between adjacent molecules is strong and uniform throughout the entire crystal. 

Molecular Crystals J.P. Pouget, Structural Instabilities E.M. Conwell, Transport Properties C.S. Jacobsen, Optical Properties J.C. Scott, Magnetic Properties... 

The effect of magnetic field on a spin - dependent reactions in solids is valid, provided that [7] the time Tpair of particles staying in the paired state must be longer than the time needed for mixing the spin states tev, but shorter than the relaxation time rrei with the value typical for molecular crystals 10 6... 

Molecularly imprinted polymers (MIPs) oscillating quartz crystals Magnetic Toroids ... 

Crystalline substances may be classified into five major types (Sll). They vary in the kind and strength of the bond between the constituent atoms or ions, and in their electrical, magnetic, and mechanical properties. These types are metal crystals, ionic crystals, valence crystals, semiconductor crystals, and molecular crystals. 

Luneau, D. and Rey, P. (1995) New manganese(II) complexes of nitronyl nitroxide radicals. Synthesis, structure and magnetic properties. Molecular Crystals and Liquid Crystals Science and Technology Section A, 273, 81-87. 

THEORETICAL STUDY OF THE MAGNETISM IN MOLECULAR CRYSTALS USING A FIRST-PRINCIPLES BOTTOM-UP METHODOLOGY... 

In 1996, Munn extended the microscopic theory of bulk second-harmonic generation from molecular crystals to encompass magnetic dipole and electric quadrupole effects [96] and included all contributions up to second order in the electric field or bilinear in the electric field and the electric field gradient or the magnetic field. This was accomplished by replacing the usual polarization of Refs. 72 and 84 by an effective polarization as well as by defining an effective quadrupole moment. Consequently, the self-consistently evaluated local electric field and electric field gradient were expressed in terms of various molecular response coefficients and lattice multipole tensor sums (up to octupole). In this... 

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