Synthesis, Structure, and Properties of 4,7-Dimethoxybenzoctellurophene: A Molecular Pyroelectric Material

摘要

The formation of molecular crystals that possess a polar axis in the solid state is largely an unexplored area, and no generic understanding is available to this day. Materials with a polar axis (a permanent dipole moment in the solid state) potentially possess ferroelectric, piezoelectric, and pyroelectric properties.1 Pyroelectric solids are used as the key material in a variety of components, which range from microphones and infrared detectors to frequency-doubling crystals in laser technology, just to mention a few.2 Examples of the design and synthesis of organic materials with pyroelectric properties are scarce because of the difficulties in predicting the crystalline properties of matter.3 An organic material must crystallize in one of the ten polar point groups to exhibit pyroelectric properties.4 Although most organic molecules possess a permanent dipole moment, few crystallize in a polar space group. Generally, derivatives based on meta-disubstituted benzene have proven to be useful as they have a tendency to crystallize in one of these ten required polar point groups and, thus, exhibit a pyroelectric effect.5 Apart from this rather vague design rule, little is known about the structural features that promote crystallization in a polar point group, and it is only on the odd and unexpected occasion that novel pyroelectric materials appear.