This work is based on our previous reported experimental results (RSC Advances, 2016, 6, 27000). The mechanism of constructing oxindoles via tandem radical reaction of N-arylacrylamide with tertiary cycloalkanols is theoretically explored by using density functional theory (DFT). A four-step mechanism was put forward for the reaction. Step 1 is related with the ring-opening process of cycloalkanol radical after the oxidation, step 2 corresponds to the intermolecular attack between keto-included alkyl radical and N-methyl-N-phenylmethacrylamide, step 3 is associated with the intramolecular C–C bond formation via the cationic attack, and step 4 is the deprotonation towards the final product. It is found that step 2 is the rate-limiting step. Importantly, step 3 is updated to be a cationic step (channel 2), instead of the previously suggested radical step (channel 1). After the ring-opening processes, comparative study indicates that the intramolecular reactions of β-, γ-, and δ-keto radicals determines the product selectivity. The low selectivity of product in the cyclopentanol-involved reaction would originate from the high competition between intra- and intermolecular reactions, which is in agreement with our previous experimental observations.

•A series of charged dinuclear Cu(I) complexes were developed using functionalized ligands.•The solution-processed OLED based on the Cu(I) complex showed a record EQE of 6.09%.•These Cu(I) complexes showed great potential for fabricating single-emitter warm WOLEDs.A series of charged dinuclear Cu(I) complexes were developed by functionalization of both central bipyrimidine-based ligands and organic phosphine ligands. The chemical modification of the ligands can effectively affect the absorption, emission and thermal stability properties of the Cu(I) complexes. The decomposition temperatures (Td) are improved by using bulky ligands. Interestingly, the complexes with the triphenylamine group on the bipyrimidine ligand show higher photoluminescence quantum yield (PLQY) than the complexes bearing the triphenylphosphine oxide group, while the complexes having the triphenylamine group on the phosphine ligand display lower PLQY. The functional groups also show an obvious influence on the redox behaviors of these complexes. Most importantly, the organic light-emitting diodes (OLEDs) based on selected dinuclear Cu(I) complexes show impressive EL features. The best performance is achieved by the device based on complex Cu-MD-1 with the maximum external quantum efficiency (EQE) of 6.09%, current efficiency (CE) of 12.78 cd A−1 and power efficiency (PE) of 5.93 lm W−1, representing the state-of-the-art EL efficiencies reported for the charged Cu(I) complexes. In addition, the OLEDs based on these Cu(I) complexes can emit warm white light with Color Rendering Index (CRI) as high as 88 and Commission Internationale Ed I'eclairage (CIE) coordinates close to (0.40, 0.46), showing the great potential of these Cu(I) complexes in fabricating single-emitter warm WOLEDs.Functionalized bipyrimidine-based charged dinuclear Cu(I) complexes are developed to show great potential for highly efficient OLEDs as well as single-emitter WOLEDs.Download high-res image (270KB)Download full-size image

•Au(I) acetylides with diethynyl aromatic ligands showing different electronic features.•Structure–property relationship for photophysical and optical power limiting properties of the Au(I) acetylides•The Au(I) acetylides can show comparable or even better optical power limiting performance than C60.Three Au(I) acetylides have been prepared by coupling (PPh3)AuCl to the diethynyl aromatic ligands with different electronic features under mild condition. Their photophysical properties and optical power limiting (OPL) behaviors have been investigated in detail. The emission characters of the Au(I) acetylides can vary dramatically by exhibiting either singlet or triplet emission signal through changing the chemical structures of the diethynyl aromatic ligands. In addition, the OPL behaviors of the Au(I) acetylides are also affected by the diethynyl aromatic ligands to show different OPL mechanism. It has been shown that the diethynyl aromatic ligand with neither electron-rich nor electron-deficient features should benefit the OPL performance of the Au(I) acetylides in view of both OPL activity and transparency. Furthermore, the Au(I) acetylides can show comparable or even better OPL performances than the state-of-the-art C60, indicating their great potential in the field of laser protection. All the obtained results should provide valuable information for design high performance OPL materials based on Au(I) acetylides.The Au(I) acetylides bearing diethynyl aromatic ligands with different electronic features are developed as high-performance optical power limiting materials comparable or even better than C60.

Under controlled conditions, platinum(II) polymetallaynes with different 2,2′-biimidazole-based organic spacers have been synthesized readily. Their photophysical properties and fluorescent response behaviors to Cu2+ ions have been investigated in detail. By adjusting both the configuration of the 2,2′-biimidazole-based spacers and the steric effect, the fluorescent response behaviors of the polymetallaynes to Cu2+ ions can be tuned dramatically. The fluorescent signal from the polymetallayne with an optimized structure can be quenched rapidly by Cu2+ ions with a high Stern–Volmer constant KSV of ca. 6.8 × 104 M−1 and a low detecting limit (DL) of ca. 0.99 ppm. These results not only highlight the great potential of these polymetallaynes as novel Cu2+ sensors, but also provide new strategies for optimizing the sensing abilities of the 2,2′-biimidazole-based ion sensors.

•Diphenylamine modified IrIIIbis(phenylpyridinato)-4-carboxylpicolinate was synthesized.•Diphenylamine influenced absorption energy and orbital electron density distribution.•Conversion efficiency of 2.51% and open circuit voltage of 0.68 V was achieved.The new complex IrIIIbis(4-diphenylaminophenylpyridinato)-4-carboxylpicolinate (complex 3) tailored by electron-donating diphenylamine (DPA) was synthesized and characterized for dye-sensitized solar cells (DSSCs) application. The introduction of the DPA moiety to phenylpyridine ligand makes the absorption bands of the complex 3 extend to 650 nm, and adjusts the highest occupied molecule orbital to be mainly localized on DPA-ppy (diphenylaminophenylpyridine) ligands (accounting for 74.44% for one DPA-ppy ligand) while the lowest unoccupied molecule orbital to be lied on the pic (pyridine-2,4-dicarboxyl acid) moiety (96.80%). TD-DFT calculation further shows the charge-transfer transitions from ligand DPA-ppy and Ir atom to the pic anchoring moiety principally contribute to the absorption bands of the complex 3 in the visible region, which is well beneficial to electron injecting into TiO2 film. For DSSCs using complex 3 as sensitizer, the energy conversion efficiency is up to 2.51%, with a short circuit current density of 7.51 mA/cm2 and an open circuit voltage of 0.68 V. These results indicate that it is possible for IrIII complex to achieve more efficient cell parameters if more rational IrIII complexes are developed.The diphenylamine was introduced to IrIIIbis(phenylpyridinato)-4-carboxylpicolinate to improve light-harvesting capacity of the resulting complex and induce favorable orbital electron density distribution for electron-injecting into TiO2 film when used as photosensitizer of dye-sensitized solar cells. As a result, a 2.51% conversion efficiency and 0.68 V open circuit voltage was achieved.

•New IrIII complexes based on 2-phenylimidazo[1,2-a]pyridine-type ligands.•The photophysical and electroluminescent features of the complexes.•These complexes show balanced charge-transporting features.New iridium(III) cyclometalated complexes based on 2-phenylimidazo[1,2-a]pyridine-type ligands were synthesized and their photophysical, electrochemical and electroluminescent (EL) properties were investigated. The detailed insight into the characters of the emissive excited states was obtained by frontier molecular orbital analysis. These metal complexes exhibit very balanced charge transporting ability for both kinds of charge carriers, which can furnish decent EL performance in the phosphorescent organic light-emitting devices (PHOLEDs) with peak luminance of 15491 cd m−2 at ca. 13.5 V, external quantum efficiency of 6.81%, luminance efficiency of 34.74 cd A−1, and power efficiency of 17.54 lm W−1. These results not only provide a better understanding of the inherent characters of IrIII phosphors with phenylimidazo[1,2-a]pyridine units, but also valuable information on future molecular design of triplet emitters with unique electronic features for high-performance PHOLEDs.New phenylimidazo[1,2-a]pyridine-based phosphorescent emitters of iridium have been developed. The balanced charge-transporting features for both kinds of charge carriers can bring about decent device performance, revealing the great potential of the phenylmidazo[1,2-a]pyridine-based IrIII phosphorescent materials.

The title reaction is investigated in detail theoretically using density functional theory. After 5-endo-dig cyclization by nucleophilic attack, five possible pathways are taken into account in this work: direct ring expansion followed or accompanied by proton-transfer (paths A and B, respectively), 1,3-cationic migration (path C), proton-transfer before ring expansion (path D), and processing via a gold-nitrene (path E). Results indicate that the reaction would undergo the favored sequential pathway (path A) rather than other pathways. Moreover, the concerted mechanism (path B), which is designed to account for the selectivity of product in the experiment, would be unlikely in the reaction. The selectivity of product could be explained by the hindrance of ligand (t-BuXPhos) and the stability of the carbocation. Moreover, the binding energy of product complexes could account for the observed reaction rate.