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A photoswitchable [2]rotaxane with unique photogated macrocyclic shuttling is constructed by incorporating the photoswitchable azobenzene (AB) and nonphotoactive biphenyl (BP) units into the axle as two terminal recognition sites, bridged by a naphthalene (NAP) unit. The UV (λ = 379 nm)/blue (λ = 440–450 nm) lights triggered Z/E photoisomerization of the AB unit can drive the cyclobis(paraquat-p-phenylene) (CBPQT4+) macrocycle to shuttle between the two terminal recognition sites. Such macrocyclic translational movement can be photogated by a steric barrier generating from the green-light (λ = 520–525 nm)-triggered cycloaddition reaction between the NAP unit on the thread and a triazolinedione (TAD) additive. Upon standing in dark, the photocycloadduct undergoes disassociation which restores the phototriggered macrocyclic shuttling ability. The construction of such photogated photoresponsive molecular shuttle can provide new approach to improve the switching controllability of rotaxane, which is beneficial to fabricate rotaxane-based nanosystems and materials with high performance.

A series of fully rigid rod–rod type amphiphilic molecules have been constructed by using 4,4′-bipyridin-1-ium or 4,4′-bipyridin-1,1′-diium (viologen) as a hydrophilic segment and phenyl, biphenyl or para-tert-phenyl as a hydrophobic unit. The crystal structures of four of the molecules have been elucidated. TEM, SEM, AFM, and DLS experiments revealed that these stiff amphiphiles could self-assemble into diverse architectures, including spherical micelles, ultra-long straight nanofibers (>1 mm), and nanotubes in water, which depend on the hydrophilic/hydrophobic fraction ratios of the molecules.

This paper describes the self-assembling property of three series of p-phenyleneethynylene based comb-like oligomers, which carry multiple peripheral side chains of different polarity. The new oligomers are prepared readily through the formation of the hydrazone bonds from the corresponding aldehyde and gallic acid-derived benzohydrazides. In polar solvents such as methanol and ethanol, the oligomers that bear n-decyl or 2-(2-(dioctylamino)-2-oxoethyl-amino)-2-oxoethoxyl unit (DOAOE) segments as the side chains are revealed to form vesicular structures, while the oligomers carrying hydrophilic oligo(ethyleneglycol) side chains do not. The structures of the vesicles are evidenced by SEM, AFM, TEM, and dye-encapsulation experiments. UV-vis absorption spectroscopic experiments suggest that the vesicles are generated through the stacking of the conjugated backbones, which is promoted by the solvophobic interaction of the peripheral side chains. (C) 2012 Elsevier Ltd. All rights reserved.