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

Abstract

The synthesis of molecular rod 1 comprising a central redox‐active unit and two terminal acetyl‐protected sulfur groups is reported. Various protecting groups for the catechol moiety were investigated and protected precursors 14–18 were synthesized. In particular, ethyl orthoformate 17 can be easily and selectively deprotected in mild acidic conditions ruling out the need for a strong Lewis acid like boron tribromide. The redox activity of 1 was confirmed by cyclic voltammetric investigations. Gold–molecule–gold junctions were formed with the dimethyl‐protected rod 18. Single‐molecule transport investigations using this molecular rod revealed a set of three single‐junction conductance values varying over two orders of magnitude.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

Metal–Molecule–Metal Junctions in Langmuir–Blodgett Films Using a New Linker: Trimethylsilane

“…This value is the same order of magnitude as the conductance value obtained for other OPE derivatives using thiols as anchoring groups (1.8 10 À5 G 0 ). [48,49] Therefore, it is concluded that both the amino and trimethylsilane groups are alternative linkers that provide electronic coupling between the electrodes and the molecule which is essentially as efficient as that through thiols. However, outside the À0.6 to + 0.6 voltage range the response deviates from linearity showing a sigmoidal behaviour over the full voltage region.…”

Rigid‐Strut‐Containing Crown Ethers and [2]Catenanes for Incorporation into Metal–Organic Frameworks

“…Compound 17 :22 Compound 16 (19.2 g, 68.1 mmol) was dissolved in CH 2 Cl 2 (100 mL) and the solution was cooled to 0 °C. A solution of ICl (23.1 g, 0.14 mol) in CH 2 Cl 2 (100 mL) was added slowly.…”

“…Solvent was removed in vacuo and the residue was purified by flash chromatography (SiO 2 : hexane/CH 2 Cl 2 = 10:1) to give the product 16 as a colorless oil (82.5 g, 89 %). 1 Compound 17: [22] Compound 16 (19.2 g, 68.1 mmol) was dissolved in CH 2 Cl 2 (100 mL) and the solution was cooled to 0 8C. A solution of ICl (23.1 g, 0.14 mol) in CH 2 Cl 2 (100 mL) was added slowly.…”

“…The organic layer was separated and dried (MgSO 4 ). The solvent was removed in vacuo and the crude product was purified by flash chromatography (SiO 2 : hexane/ CH 2 Cl 2 = 10:1) to give 17 as a yellowish oil (21. Compound 18: [22,23] Compound 17 (1.80 g, 4.62 mmol) was dissolved in CH 2 Cl 2 (20 mL) and the solution was cooled to À78 8C. BBr 3 (2 mL, 5.30 g, 21.2 mol) was added and the reaction mixture was warmed to room temperature and was stirred for 14 h. The reaction was poured into ice/H 2 O and the mixture was extracted with EtOAc, and the organic layer was separated and dried (Na 2 SO 4 ).…”

Synthesis, Electrochemical Behavior, and Self‐Assembly of Metallocene‐Functionalized Thiofluorenes

“…[6] Among other possible architectures, thiols with redox-active tail groups (e.g., ferrocenyl, [7][8][9][10][11][12][13] ruthenocenyl, [14] or other [15][16][17] moieties) can be used as potential candidates for SAM formation on suitable substrates (e.g., coinage metals or GaAs). [18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36] The corresponding molecular films can then be used in different electrochemical applications with the substrate itself acting as a positive or negative electrode depending on the need.…”