A Ni(ii) catalyst incorporated into a new porous organic polymer, Ni(ii)-POP-1, is prepared via a click reaction followed by metalation with NiCl2. It shows good catalytic activity for ethylene dimerization.
Mn(III)‐porphyrin containing #heterogeneous catalyst based on microporous polymeric constituents as a new class of #catalyst support from Korea University and Seoul National University of Science and Technology
Due to the recent progress on large and high-resolution displays, the development of new materials for organic lightemitting diodes (OLEDs) with high electroluminescence efficiency has become one of the forefronts of modern display research. 1,2 In particular, there has been tremendous research interests on the highly efficient phosphorescent materials, because of their long-lifetime and high quantum efficiency. 3 In addition, the development of suitable hosts that may be employed in host-dopant system has become one of the most extensively studied areas in phosphorescentbased OLEDs, because it is well known that the system may suffer from the excitation instability caused by using only the dopant. 4 The latest development of phosphorescent OLEDs shows close to 20% of quantum efficiency, 5 but these phosphorescent materials are usually very expensive. 6 After the pioneering works by Adachi and coworkers, 7 thermally activated delayed fluorescence (TADF) has recently been realized as a next generation of light-emitting system and it has been gradually considered as another suggestion for fluorescence and phosphorescence-based OLEDs. Remarkably, these materials often show extremely high quantum efficiency, 8 because TADF uses singlet and triplet excitons that effectively undergo internal conversion through reverse intersystem crossing (RISC) from triplet excited state (T 1 ) to singlet excited state (S 1 ). This process is considered to be an important step for high quantum efficiency because it depends heavily on how easy the RISC process takes place. 7,9 This RISC may be facilitated when the material has a small energy gap (ΔE st ) between singlet and triplet excited states. 10 But yet, this small ΔE st can be accomplished by restricting deliberately the orbital overlap between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO). 11 In a molecular system, a twisted structure between the donor and the acceptor is highly recommended for the restriction of orbital overlaps 12 and the internal quantum efficiency of a properly designed TADF system is projected to be over 90%. 13 Thus, materials using the TADF mechanism exhibit a great potential as a cost-effective alternative to rare metalbased phosphorescent materials.In here, we like to discuss the synthesis and photoluminescence (PL) characteristics of carbazole-containing terephthalonitrile derivatives (Figure 1) showing outstanding TADF properties. The preparation details including their characterizations are described in Appendix S1, Supporting Information (Schemes S1 and S2). With terephthalonitrile moiety, which contains a cyano group at ortho position, the distorted geometry between acceptors and donors is enhanced and results a small ΔE st between singlet and triplet states.In order to study the photophysical properties of 1 and 2,
A new type of bispyridine (bpy) incorporated POP was prepared via a cobalt-catalyzed acetylene trimerization. Subsequent metalation of CuCl2 gave POP-Cu(ii) which displayed outstanding olefin oxidation activity.
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