title: Synthesis, multiphase characterization, and helicity control in chiral DACH-linked oligothiophenes.
abstract: A new class of chiral oligothiophenes is described. Mono-, bi-, ter-, and quarterthiophenes have been linked to enantiopure trans-1,2-cyclohexanediamine (DACH) via diamino or diimino moieties. The stereochemistry of DACH, the type of linker, and oligothiophene size determine the conformational flexibility of these molecules and consequently their molecular and supramolecular helicity in solution and in the solid state. The case of diaminobis(bithiophene), which inverts helicity and shows chiral amplification in the transition from solution to film, is described in detail. Based on the combined use of circular dichroism in solution and in the solid state, single-crystal/thin-film X-ray diffraction, and polarized optical microscopy, a working mechanism has been proposed to explain this unexpected behavior.
authors.affiliation: Istituto per la Sintesi Organica e la Fotoreattività (ISOF), Consiglio Nazionale Ricerche, Via Gobetti 101, 40129 Bologna, Italy. mmelucci@isof.cnr.it
authors.forename: Manuela
authors.initials: M
authors.lastname: Melucci
authors.forename: Giovanna
authors.initials: G
authors.lastname: Barbarella
authors.forename: Massimo
authors.initials: M
authors.lastname: Gazzano
authors.forename: Massimiliano
authors.initials: M
authors.lastname: Cavallini
authors.forename: Fabio
authors.initials: F
authors.lastname: Biscarini
authors.forename: Alessandro
authors.initials: A
authors.lastname: Bongini
authors.forename: Fabio
authors.initials: F
authors.lastname: Piccinelli
authors.forename: Magda
authors.initials: M
authors.lastname: Monari
authors.forename: Marco
authors.initials: M
authors.lastname: Bandini
authors.forename: Achille
authors.initials: A
authors.lastname: Umani-Ronchi
authors.forename: Paolo
authors.initials: P
authors.lastname: Biscarini