Tunable multicolor supramolecular assemblies based on phosphorescence cascade energy transfer for photocatalytic organic conversion and anti-counterfeiting.

Making full use of the captured energy by phosphorescence light-harvesting systems (PLHSs) and the tunable photoluminescence in energy transfer process to realize the multiple applications is still the challenge of PLHSs research. In this study, we have successfully constructed a highly effective PLHS with tunable multicolor luminescence and efficient conversion of photosensitizer types, which can further be used in photocatalytic organic conversion, information anti-counterfeiting and storage. The supramolecular polymer of BDBP-CB[8], which is generated by cucurbit[8]uril (CB[8]) and 4-(4-bromophenyl)-pyridine derivative (BDBP), realizes a phosphorescence emission and a change in luminescence color. Notably, white light emission was achieved and the logic gate systems were constructed utilizing the application of adjustable luminescence color. More interestingly, PLHS can be constructed by employing BDBP-CB[8] as energy donors, Sulforhodamine 101 (SR101) and Cyanine5 (Cy5) as energy acceptors, which results in a remarkably tunable multicolor photoluminescence to achieve the information storage. Furthermore, we have also found that BDBP-CB[8] can serve as type II photosensitizer for the effective production of singlet oxygen (1O2) during the photooxidation process of styrene in aqueous environments, attaining a remarkable output rate reaching as high as 89 %. Particularly, compared with 1O2 produced by type II photosensitizer BDBP-CB[8], the construction of PLHS can effectively convert type II photosensitizer to type I photosensitizer and efficiently generate superoxide anion radical (O2•-), which can be used for photocatalytic cross-dehydrogenative coupling (CDC) reaction in the aqueous solution with a yield of 90 %. Thus, we have created a PLHS that not only achieves tunable multicolor emission for information anti-counterfeiting and storage, but also realizes the conversion of reactive oxygen species (ROS) for different types photocatalytic oxidation reactions.

Highly Efficient Amide Michael Addition and Its Use in the Preparation of Tunable Multicolor Photoluminescent Polymers.

The amide bond is one of the most pivotal functional groups in chemistry and biology. It is also the key component of proteins and widely present in synthetic materials. The majority of studies have focused on the formation of the amide group, but its postmodification has scarcely been investigated. Herein, we successfully develop the Michael additions of amide to acrylate, acrylamide, or propiolate in the presence of phosphazene base at room temperature. This amide Michael addition is much more efficient when the secondary amide instead of the primary amide is used under the same conditions. This reaction was applied to postfunctionalize poly(methyl acrylate-co-acrylamide), P(MA-co-Am), and it is shown that the amide groups of P(MA-co-Am) could be completely modified by N,N-dimethylacrylamide (DMA). Interestingly, the resulting copolymer exhibited tailorable fluorescence with emission wavelength ranging from 380 to 613 nm, which is a desired property for luminescent materials. Moreover, the emissions of the copolymer increased with increasing concentration in solution for all excitation wavelengths from 320 to 580 nm. Therefore, this work not only develops an efficient t-BuP4-catalyzed amide Michael addition but also offers a facile method for tunable multicolor photoluminescent polymers, which is expected to find a wide range of applications in many fields, such as in anticounterfeiting technology.