Rotaxanes and pseudorotaxanes with threads containing viologen units

Abstract

In the present review rotaxanes and pseudorotaxanes with threads containing viologen units are described. First the rotaxanes and pseudorotaxanes in which the crown ether serves as a ring are presented, they are followed by rotaxanes and pseudorotaxanes containing the crown-based cryptand as a ring. For the above interlocked species the synthetic approaches and properties, especially those promising for their use in sensors and switches are shown.

Magnetic and Photochromic Properties of a Manganese(II) Metal-Zwitterionic Coordination Polymer

“…Viologen cations (V 2+ , N,N ′-disubstituted 4,4′-bipyridiniums) are electron-deficient species exhibiting excellent charge-transfer and redox properties with photoactivity . The availability of three oxidation states (V 2+ , V •+ , and V 0 ) has evoked much interest in the study of viologens as catalysts or electron relays in chemical or photochemical redox systems and as chemo-/electro-/photoresponsive materials for applications such as electrochromic display, smart windows, molecular machines, and switches .…”

Synthesis of Bottlebrush Copolymers Using a Polypseudorotaxane Intermediate

“…Polyester 1 (Figure ) derived from bis­( m- phenylene-32-crown-10 diacid and bisphenol-A was on hand from previous studies. , Viologen 2 (Figure ), also used previously, was fitted with two terminal NMP species in the form of TEMPO units. As noted above, viologens (N,N′-dialkyl-4,4′-dipyridinium salts) are known to form pseudorotaxanes with bis­( m- phenylene)-32-crown-10 species and other crown ethers. − In these experiments, styrene was chosen as the brush monomer; it undergoes smooth NMP. − Polyester 1 and one-half molar equivalent (relative to the crown moieties) of viologen 2 were dissolved in styrene to form a yellow solution, indicative of pseudorotaxane formation as previously reported. ,,,,,,, In two different experiments, the present solutions were immersed in an oil bath held at 120 °C to initiate NMP. In the first experiment, the reaction was allowed to proceed for 16 h, and in the second experiment polymerization was limited to 4 h, leading to products containing high- and low-molecular-weight polystyrene brushes, 3a and 3b , respectively (Figure ).…”