title: Columnar mesophases based on zinc chlorophyll derivatives functionalized with peripheral dendron wedges.
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.
authors.affiliation: Universität Würzburg, Institut für Organische Chemie and Röntgen Research Center for Complex Material Systems, Am Hubland, 97074 Würzburg, Germany.
authors.forename: Sanchita
authors.initials: S
authors.lastname: Sengupta
authors.forename: Shinobu
authors.initials: S
authors.lastname: Uemura
authors.forename: Sameer
authors.initials: S
authors.lastname: Patwardhan
authors.forename: Valerie
authors.initials: V
authors.lastname: Huber
authors.forename: Ferdinand C
authors.initials: FC
authors.lastname: Grozema
authors.forename: Laurens D A
authors.initials: LD
authors.lastname: Siebbeles
authors.forename: Ute
authors.initials: U
authors.lastname: Baumeister
authors.forename: Frank
authors.initials: F
authors.lastname: Würthner
mesh_terms: D001429:Bacteriochlorophylls / Q000737:chemistry; D002734:Chlorophyll / Q000138:chemical synthesis* / Q000737:chemistry; D000077194:Chlorophyll A; D008665:Metalloporphyrins / Q000737:chemistry*; D008859:Microscopy, Polarization; D016252:Microscopy, Scanning Tunneling; D015394:Molecular Structure; D010860:Pigments, Biological / Q000138:chemical synthesis / Q000737:chemistry; D011166:Porphyrins / Q000737:chemistry*; D014961:X-Ray Diffraction; D015032:Zinc / Q000737:chemistry*
chemical_list: D001429:Bacteriochlorophylls; D008665:Metalloporphyrins; D010860:Pigments, Biological; D011166:Porphyrins; C558702:zinc chlorin; D002734:Chlorophyll; C006969:chlorin; D015032:Zinc; D000077194:Chlorophyll A