Supramolecular Order of 2,5-Bis(dodecanoxy)phenyleneethynylene鈥揃utadiyne Oligomers in the Solid State

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• 作者：Edgar Vergara ; Eduardo Arias ; Ivana Moggio ; Carlos Gallardo-Vega ; Ronald F. Ziolo ; Rosa M. Jim茅nez-Barrera ; Damaso Navarro ; Oliverio Rodr铆guez ; Salvador Fern谩ndez ; Manuel Herrera
• 刊名：Langmuir
• 出版年：2015
• 出版时间：June 23, 2015
• 年：2015
• 卷：31
• 期：24
• 页码：6909-6916
• 全文大小：655K
• ISSN：1520-5827

文摘

The supramolecular order of a 2,5-bis(dodecanoxy)phenyleneethynylene鈥揵utadiyne 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 蟺鈥撓€ interaction that governs the package of conjugated backbones was evidenced by the reiterative distances of 0.36 卤 0.017 nm found by SWAXS and 0.32 卤 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鈥損henyl distance of 0.34 nm, suggesting that the molecules are stacked in lamellae perpendicularly aligned to the substrate.