The separation of benzene and cyclohexane
is one of the most challenging
tasks in the petrochemical field. However, conventional separation
methods suffer from cumbersome operation, huge energy expenditure,
or use of entrainers. Herein, we develop an environmentally friendly
and energy saving adsorptive separation strategy using nonporous adaptive
crystals of a hybrid[3]arene (1). Adaptive 1 crystals separate benzene from an equimolar benzene/cyclohexane
mixture with a purity of 97.5%. The selectivity comes from the stability
and variability of the new crystal structure upon capture of the preferred
guest, benzene. Moreover, reversible transformations between the nonporous
guest-free structure and the guest-containing structure make 1 highly recyclable.
In order to promote the development of photodynamic therapy (PDT), undesired side effects like low tumor specificity and the "always-on" phenomenon should be avoided. An effective solution is to construct an adaptive photosensitizer that can be activated to generate reactive oxygen species (ROS) in the tumor microenvironment. Herein, we design and synthesize a supramolecular switch based on a host-guest complex containing a water-soluble pillar[5]arene (WP5) and an AIEgen photosensitizer (G). The formation of the host-guest complex WP5'G quenches the fluorescence and inhibits ROS generation of G. Benefitting from the pH-responsiveness of WP5, the binding site between G and WP5 changes in an acidic environment through a shuttle movement. Consequently, fluorescence and ROS generation of the host-guest complex can be switched on at pH 5.0. This work offers a new paradigm for the construction of adaptive photosensitizers by using a supramolecular method. Scheme 1. Chemical structures and cartoon representations of WP5, P5 and G.
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