Synthesis of Macrocyclic Molecular Rods as Potential Electronic Devices

Abstract

The design and synthesis of the macrocycles 1 and 2 as model compounds for the investigation of negative differential conductance phenomena in molecular junctions are reported. The macrocycles 1 and 2 comprise a molecular rod subunit consisting of three ethynyl‐linked phenyl rings. While the rotational freedom along the rod axis of both terminal phenyl rings is limited by the macrocyclic frame, the central phenyl ring is revolving. The rod substructure is terminally functionalized with acetyl‐protected thiol groups to enable its immobilization between gold contacts. The central phenyl ring is functionalized with one and two nitro groups for 1 and 2, respectively. The nitro groups are of particular importance as i) both macrocycles are model compounds to investigate a hypothetical intramolecular interaction of the nitro group with the opposite macrocyclic subunits and ii) the nitro group(s) result in limited thermal stability of the compounds due to the intramolecular rearrangement to macrocycles comprising isatogen subunits. These highly functionalized macrocycles have been assembled by acetylene scaffolding strategies in combination with functional group transformation chemistry.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

Redox‐Active Catechol‐Functionalized Molecular Rods: Suitable Protection Groups and Single‐Molecule Transport Investigations

“…[65][66][67][68] To our satisfaction, concomitant removal of the ethyl orthoformate protecting group and trans-protection of both terminal sulfur groups was successful with tert-butylsulfanyl orthoester 19, giving the target acetylsulfanyl rod 1 in a good 79 % yield (Scheme 8). …”

The First Postsynthetic 5′‐5′ Intercalators in Triplex DNA – Solid‐Phase Postsynthetic Sonogashira Reaction and Homocouplings on Arylacetylenes

“…130 -1358. 1 [24]; 455 mg, 2.01 mmol) was dissolved in dry Et 3 N (50 ml) and flushed with Ar, before CuI (34 mg, 0.18 mmol) and Pd(PPh 3 ) 2 Cl 2 (72 mg, 0.10 mmol) were added. Compound 1 (1.34 g, 4.8 mmol) was added via a syringe, and the mixture was stirred at r.t. under Ar for 18 h. The solvent was removed under reduced pressure, and the residue was dissolved in CH 2 Cl 2 (100 ml) which was washed with 0.3m aq.…”

Oligoaryl Cruciform Structures as Model Compounds for Coordination‐Induced Single‐Molecule Switches

“…[55,56] Recently we proposed to profit from the potential dependent coordination of pyridines to gold electrodes [17,[57][58][59] as switching mechanism in an electrochemically controlled junction. A molecular cruciform consisting of two bars with different transport features and different terminal anchor groups was suggested.…”