title: Supramolecular Order of 2,5-Bis(dodecanoxy)phenyleneethynylene-Butadiyne Oligomers in the Solid State.
abstract: The supramolecular order of a 2,5-bis(dodecanoxy)phenyleneethynylene-butadiyne series of rod-like oligomers with 2, 4, 6, and 8 phenyleneethynylene moieties was studied in the solid state by differential scanning calorimetry (DSC), temperature-dependent small- and wide-angle X-ray scattering (SWAXS), selected area electron diffraction (SAED), polarized optical microscopy (POM), high-resolution transmission microscopy (HRTEM), and scanning tunneling microscopy (STM). It was found that all of the oligomers self-assemble in blocks of molecules that resemble bricks that are randomly oriented. These oligomers are described as sanidic liquid crystals as a term to classify their mesomorphic behavior because of their brick or board-like structure. The strong π-π interaction that governs the package of conjugated backbones was evidenced by the reiterative distances of 0.36 ± 0.017 nm found by SWAXS and 0.32 ± 0.017 nm found by HRTEM. A STM study of a cast film of the tetramer deposited on highly oriented pyrolitic graphite (HOPG) allowed for the visualization and determination of the conjugated backbone length of 2.48 nm and a phenyl-phenyl distance of 0.34 nm, suggesting that the molecules are stacked in lamellae perpendicularly aligned to the substrate.
authors.affiliation: †Centro de Investigación en Química Aplicada (CIQA), Boulevard Enrique Reyna 140, 25294 Saltillo, Coahuila, Mexico.
authors.forename: Edgar
authors.initials: E
authors.lastname: Vergara
authors.affiliation: †Centro de Investigación en Química Aplicada (CIQA), Boulevard Enrique Reyna 140, 25294 Saltillo, Coahuila, Mexico.
authors.forename: Eduardo
authors.initials: E
authors.lastname: Arias
authors.affiliation: †Centro de Investigación en Química Aplicada (CIQA), Boulevard Enrique Reyna 140, 25294 Saltillo, Coahuila, Mexico.
authors.forename: Ivana
authors.initials: I
authors.lastname: Moggio
authors.affiliation: †Centro de Investigación en Química Aplicada (CIQA), Boulevard Enrique Reyna 140, 25294 Saltillo, Coahuila, Mexico.
authors.forename: Carlos
authors.initials: C
authors.lastname: Gallardo-Vega
authors.affiliation: †Centro de Investigación en Química Aplicada (CIQA), Boulevard Enrique Reyna 140, 25294 Saltillo, Coahuila, Mexico.
authors.forename: Ronald F
authors.initials: RF
authors.lastname: Ziolo
authors.affiliation: †Centro de Investigación en Química Aplicada (CIQA), Boulevard Enrique Reyna 140, 25294 Saltillo, Coahuila, Mexico.
authors.forename: Rosa M
authors.initials: RM
authors.lastname: Jiménez-Barrera
authors.affiliation: †Centro de Investigación en Química Aplicada (CIQA), Boulevard Enrique Reyna 140, 25294 Saltillo, Coahuila, Mexico.
authors.forename: Damaso
authors.initials: D
authors.lastname: Navarro
authors.affiliation: †Centro de Investigación en Química Aplicada (CIQA), Boulevard Enrique Reyna 140, 25294 Saltillo, Coahuila, Mexico.
authors.forename: Oliverio
authors.initials: O
authors.lastname: Rodríguez
authors.affiliation: †Centro de Investigación en Química Aplicada (CIQA), Boulevard Enrique Reyna 140, 25294 Saltillo, Coahuila, Mexico.
authors.forename: Salvador
authors.initials: S
authors.lastname: Fernández
authors.affiliation: ‡Centro de Nanociencias y Nanotecnología, Universidad Nacional Autónoma de México, 22800 Ensenada, Baja California, Mexico.
authors.forename: Manuel
authors.initials: M
authors.lastname: Herrera