10.1021/ja310694t.s003 Gregory C. Welch Gregory C. Welch Ronald C. Bakus Ronald C. Bakus Simon J. Teat Simon J. Teat Guillermo C. Bazan Guillermo C. Bazan Impact of Regiochemistry and Isoelectronic Bridgehead Substitution on the Molecular Shape and Bulk Organization of Narrow Bandgap Chromophores American Chemical Society 2013 molecules center changes Isoelectronic Bridgehead Substitution fragment banana shape Narrow Bandgap ChromophoresA comparison pyridyl 2013-02-13 00:00:00 Dataset https://acs.figshare.com/articles/dataset/Impact_of_Regiochemistry_and_Isoelectronic_Bridgehead_Substitution_on_the_Molecular_Shape_and_Bulk_Organization_of_Narrow_Bandgap_Chromophores/2444185 A comparison of two classes of small molecules relevant to the field of organic electronics is carried out at the molecular and supramolecular levels. First, two molecules that differ only in the position of a pyridyl N-atom within an acceptor fragment are compared and contrasted. X-ray investigation of single crystals reveals that positioning the pyridyl N-atoms <i>proximal</i> to the molecules center changes the molecular shape by bending the molecule into a banana shape. Second, we demonstrate that the banana shape of the molecule can be controlled by replacing a Si atom within the dithienosilole fragment with a C or Ge atom. Here, utilization of cyclopentadithiophene or dithienogermole as the internal electron-rich unit leads to a decrease or an increase in the bending of the conjugated backbone, respectively. Such molecular shape changes alter intermolecular packing and thus affect bulk properties, leading to large differences in the optical, thermal, and crystallization properties.