Columnar mesophases based on zinc chlorophyll derivatives functionalized with peripheral dendron wedges |
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Authors: | Sengupta Sanchita Uemura Shinobu Patwardhan Sameer Huber Valerie Grozema Ferdinand C Siebbeles Laurens D A Baumeister Ute Würthner Frank |
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Institution: | 1. Universit?t Würzburg, Institut für Organische Chemie and R?ntgen Research Center for Complex Material Systems, Am Hubland, 97074 Würzburg (Germany), Fax: (+49)?931‐31‐84756;2. OptoElectronic Materials Section, DelftChemTech, Delft University of Technology, Julianalaan 136, 2628 BL Delft (The Netherlands);3. Martin‐Luther‐Universit?t Halle‐Wittenberg, Institut für Chemie, Physikalische Chemie, von‐Danckelmann‐Platz 4, 06120 Halle (Germany) |
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Abstract: | A chlorophyll derivative with a central zinc ion, a methoxy functionality at its 3(1)-position, and functionalized with a second-generation dendron (3,4-3,4,5)12G2-CH(2)OH at its 17(2)-position was synthesized starting from natural chlorophyll a (Chl a). This compound exhibits liquid crystalline (LC) behavior and its mesomorphic properties have been characterized by differential scanning calorimetry (DSC), polarisation optical microscopy (POM), powder X-ray diffraction (XRD), and scanning probe microscopy (SPM). A combination of powder XRD, high resolution scanning tunneling microscopy (STM), and atomic force microscopy (AFM) experiments revealed the formation of nano-segregated well-ordered columnar tubular superstructures consisting of about five molecules in the column stratum. These self-assembled columns are further self-organized into a two-dimensional oblique unit cell lattice. Semiconducting behavior of this compound has been studied by pulse-radiolysis time-resolved microwave conductivity (PR-TRMC) method and charge carrier mobility values of ~10(-2) cm(2) V(-1) s(-1) are observed. Such organized columnar superstructures constructed from semisynthetic zinc chlorins are reminiscent of the tubular organization of the bacteriochlorophyll dyes in the light-harvesting chlorosomal antennae of green sulphur bacteria. |
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Keywords: | dendrimers mesophases organic electronics self‐assembly zinc chlorin dye |
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