Pseudorotaxane complexes between viologen vinylogues and cucurbit[7]uril: New prototype of photocontrolled molecular machine

Novel Star-Shaped Viologens Containing Phenyl and Triphenylamine Moieties for Electrochromic Applications

The two star-shaped viologens containing 1,3,5-substituted phenyl (1) and triphenylamine (2) central cores and n-hexyl chains were synthesized and characterized. Both compounds exhibited promising optoelectronic properties and underwent multiple oxidation/reduction processes resulting in various colors. Four possible redox states of tripyridium salt containing a phenyl or triphenylamine core can occur depending on the applied potentials. The wide color range, from colorless through blue, azure to green-gray, was observed during the electrochemical reduction of compound 1. In the case of compound 2, the color change observed during spectroelectrochemical measurements was from yellow to colorless during the cathodic process and from yellow to green during the anodic process. The observed color change for both viologens was reversible. The triphenylamine-cored viologen (2) also exhibited emission in visible range and solvatochromism. It also exhibited luminescence in the solid state when excited with a UV lamp. These studies provide insights into the design of advanced materials for applications in displays.

An easy gene assembling strategy for light-promoted transfection by combining host-guest interaction of cucurbit[7]uril and gold nanoparticles

Cucurbit[7]uril (CB[7]), a representative member of the host family cucurbit[n]uril, can host-guest interact with many guest molecules such as adamantane, viologen and naphthalene derivatives. This host-guest interaction provides an easy strategy in gene vector assembling. Furthermore, CB[7] can self-assemble on gold nanospheres (AuNSs). Herein, the combination of CB[7] and AuNSs provides both advantages of host-guest interaction and photo-thermal effect of AuNSs. In this study, polyethyleneimine (PEI) and polyethylene glycol (PEG) were separately interacted with CB[7] via host-guest interaction. Then by assembling on AuNSs, PEI and PEG were combined together to condense DNA into polyplexes as well as enhance circulation stability of the polyplexes. These gene vectors were found to have high cellular uptake efficiency and low cytotoxicity. Furthermore, the well distributed AuNSs in the polyplexes could transform light into heat under light exposure because of the photo-thermal effect. This was found to effectively promote the entry of gene into cytoplasm and highly enhanced gene transfection efficiency.