6,13-bis(triisopropylsilylethynyl) pentacene (TIPS pentacene) was deposited on SiO2/Si substrates with Au stripes using electrostatic spray deposition (ESD). We observed that crystalline domains on the substrates were preferentially oriented. To elucidate this phenomenon, the correlation between the orientation direction and stripe direction was investigated by angle-dependent polarized Raman spectroscopy. Since the acene planes in TIPS pentacene take an edge-on orientation on the substrates, C-C ring stretch modes can be used to probe the in-plane orientation. We found that the long molecular axis of acene planes is inclined at about 50° or 110° from the stripe direction. This result suggests that the molecular orientation of the crystalline domains can be controlled by the stripes.

The properties of a material often depend on the degree of order of their atomic, molecular, or crystalline domain components. This is expected to be especially true for the case of polyacetylene, whose properties are highly anisotropic. For many applications, it may be necessary to have macroscopic order but not necessarily crystalline order. Having polyacetyelene chains fully extended and aligned parallel to each other may be sufficient for these applications even without order of the chains around their long axis. We report here progress in the use of an inclusion crystal containing a photo-reactive precursor to prepare high molecular weight polyacetylene. Raman spectroscopy was performed to probe the resulting conjugated polyene chains. Ultraviolet irradiation of a 1,4-diiodo-1,3-butadiene/urea inclusion complex results in the appearance of new resonance-enhanced Raman modes at 1125 and 1509 cm-1. The Raman spectra of the resulting confined polyene chains are very similar to freestanding isolated trans-polyacetylene prepared by solution methods.

The growth of CdTe2O5 single crystals using a modified Bridgman technique in a RF furnace was attempted. A platinum/gold crucible was used to melt the powder mixture in a customized insulated chamber to provide an adequate vertical thermal gradient. Growths resulted in mica-shaped single crystals that were extracted and investigated. Some optical and electrical properties were studied. Czochralski (CZ) method was also tried but returned very small crystals at best, whereas evaporation of CdO and/or TeO2 presented another challenge.

We present our findings on structural features and trends observed in single crystal structural studies for a series of oligothiophene and ethylenedioxythiophene (EDOT) molecules substituted with bromo and tricyanovinyl groups. The presence of a C=C bridge as well as the introduction of n-butyl solubilizing groups are also addressed. Focus of the work will be on how these structural modifications, in particular, how inter- and intra- molecular interactions impact planarity and packing of molecules in the observed crystal structures.