Date and Time:2:00.pm,Oct.14,2015
Venue:1st Meeting Room, Biochemical Engineering Building
lecture 1：Near-Infrared-Sensitive Materials Based on Ru Complex Functionalized Upconverting Nanoparticles
speaker： Wu Si(group leader) Prof.
Upconverting nanoparticles (UCNPs) convert near-infrared (NIR) light to UV or visible light that can trigger photoreactions of photosensitive compounds. This process is called UCNP-assisted photochemistry. We demonstrate UCNPs converted 974 nm light at an intensity of 0.35 W/cm2 to blue light that triggered the cleavage of photocleavable Ru complexes. This light intensity is lower than the maximum permissible exposure of skin and it is the lowest intensity reported for UCNP-assisted photochemistry. Overheating problems of NIR light were minimized and photodamage to biomaterials was prevented at such a low light intensity. We used this UCNP-assisted photochemistry for drug delivery and patterning of biomaterials.
For drug delivery, mesoporous silica coated UCNPs were loaded with the anticancer drug doxorubicin and grafted with Ru complexes as photoactive molecular valves. NIR light passed through tissue and induced cleavage of Ru complexes and release of doxorubicin. The released doxorubicin inhibited the growth of cancer cells.
To pattern proteins using NIR light, proteins and an upconverting-nanoparticle-decorated substrate were linked via photocleavable Ru complexes. The substrate was irradiated using NIR light with a photomask. In the exposed areas of the substrate, upconverting nanoparticles converted the NIR light into blue light, which induced cleavage of the Ru complexes and release of proteins.
lecture 2：Conjugated Nanoporous Polymers for Visible Light Photocatalysis: A Metal-Free Alternative
speaker：Prof. Zhang Kai (group leader)
Sunlight is a clean and inexhaustible source of renewable energy. Inspired by nature’s ability to convert solar energy in photocatalytic processes, organic chemists have developed a vast number of photocatalysts in order to mimic the nature process. However, there are still some intrinsic drawbacks associated with these homogeneous systems, for instance, high cost, toxicity of these rare metals, as well as limited availability in nature, and their additionally required post-reaction purification step for catalyst removal. It is therefore of great desire to develop stable, reusable and transition metal-free photocatalysts for organic synthesis.
In this talk, a new class of non-metallic, polymer-based materials, in particular, conjugated nanoporous polymers, combining photoactive π-electron backbone and highly porous properties, will be presented as an efficient and stable platform for heterogeneous visible light-promoted chemical transformations, such as molecular oxygen activation reaction, C-C or C-N bond formations, reductive dehalogenation reaction, visible light-initiated free radical polymerization, and direct bromination reaction on aromatic compounds.