Ladder-Type Thienoacenaphthopyrazine-Based Molecules:Synthesis,Properties,and Application to Construct High-Performance Polymer for Organic Solar Cells

We present a new design strategy to synthesize ladder-type thienoacenaphthopyrazine(TAP)-based monomers through two different coupling reactions from starting material 5,6-dibromoacenaphthylene-1,2-dione.By bringing varous electron-deficient groups together(such as five-membered aromatic rings,pyrazine,fluorine,and thiadiazols),this new family of molecules exhibits good stability in ambient conditions and easily tunes the electronic,photophysical and film-forming properties of polymers.The unique molecular shape with its extendedπ-conjugated backbone perpendicular to the polymer chain,offers a remarkable platform for the development of a semiconducting polymer with rare geometry.The planar and enlarged conjugated backbone enables TAP-based copolymers PTAP1 and PTAP2 to exhibit distinguishing solubility properties that are different from small-molecule-based polymers,indicating the advantages of novel ladder-type monomers.Their insolubility in chloroform supports orthogonal solvent processing to fabricate layer-by-layer organic solar cells(LBL-OSCs).Owing to its shorterπ–πstacking distance,higher hole mobility,and more favorable phase separation caused bymultifluorine substitution,polymer PTAP1-based LBL-OSC exhibits the highest efficiency of 17.14%by using Y6-BO as the electron acceptor while the efficiency for the PTAP2-based device is 14.20%.This high efficiency indicates the tremendous potential of these novel building units.

Hydrogen peroxide-activatable iodoBodipy-phthalhydrazid conjugate nanoparticles for cancer therapy

The dependence on outer light source strongly hinders clinical applications of photodynamic therapy(PDT)to the deep-seated tumor.However,the majority of documented PDT systems that function without the external light source rely on either the chemiluminescence resonance energy transfer(CRET)or fluorescence resonance energy transfer(FRET)mechanism,which decreases the energy transfer efficiency and reproducibility of PDT.Herein,we developed a novel single-molecule triplet photosensitizer(iodoBodipy(IBDP)-L)that can be chemiexcited to triplet excited state to generate reactive oxygen species instead of outer light irradiation.The direct bonding of phthalhydrazid moiety to iodoBodipy fluorophore evoked valid intramolecular energy transfer(IET),and once phthalhydrazid part is activated by hydrogen peroxide,the released reaction energy could excite the iodoBodipy-phthalhydrazid conjugate as a whole.Reaction product IBDP-L-COOH showed high triplet state quantum yield(ΦT=65%)and large spin-orbit coupling.A large amount of reactive oxygen species(ROS)was produced in MCF-7 cells,thus inhibiting the cell growth both in vitro and in vivo after IBDP-L was formulated into nanoparticles(NPs)via nanoprecipitation.We believe that the synthesized IodoBodipy-phthalhydrazid conjugate based on the IET mechanism will open a new door in the molecular design of efficient triplet photosensitizers for treating deeply seated tumors in the future.