Through adding two substituent phenyl groups on distyrylbenzene, we have obtained the cross stacking of 2,5-diphenyl-1,4-distyrylbenzene with two trans double bonds (trans-DPDSB) in crystalline state. In such a cross-stacking mode, the solid-state emission exhibits high-intensity, having characteristics similar to its single molecule. The organic light-emiiting diodes (OLEDs) with attractive performance have been achieved using trans-DPDSB as a light-emitting layer, and the amplified spontaneous emission of the needlelike crystals has been observed.

Strong supramolecular interactions, which induced tight packing and rigid molecules in crystals of cyano substituent oligo(para-phenylene vinylene) (CN-DPDSB), are the key factor for the high luminescence efficiency of its crystals; opposite to its isolated molecules in solution which have very low luminescence efficiency.

A meta-linked donor–acceptor (D–A) structure was utilized to achieve high-efficiency and colour-purity near ultraviolet (NUV) in organic light-emitting diodes (OLEDs).

510 wileyonlinelibrary.com COMMUNICATION www.MaterialsViews.com www.advopticalmat.detime-dependent density functional theory (TDDFT). [ 7 ] It aims to reveal the key characteristics of geometry and electronic structure that lead to the high yield of radiative singlet excitons, and provides a new insight into the molecular design for a new generation of organic EL materials.DFT is the most widely used method to describe the groundand excited-state properties from medium to large molecular systems. Taking TPA-NZP as an example, based on the optimized confi guration (DFT/B3LYP/6-31+G (d, p)) of the groundstate (S 0 ), the vertical transition energies were calculated using the methods of TD-B3LYP, [ 8 ] TD-ωB97XD, [ 9 ] and TD-M06-2X, [ 10 ] and further evaluated by EOM-CCSD [ 11 ] for the purpose of comparison. Among these methods, the M06-2X provided the results which were the closest to those data from EOM-CCSD and the experimental values after taking into account basis sets and solvent effects (see Supporting Information). Considering the computational accuracy and cost, the method M06-2X /6-31+G (d, p) was fi nally chosen to describe the excited-state properties of 4CzIPN and TPA-NZP. All the DFT and TDDFT calculations were carried out using the Gaussian 09 package [ 12 ] on a Power Leader workstation.In Figure 1 a is shown the chemical structure of 4CzIPN, which consists of four carbazoles as the donors and a dicyanobenzene core as the acceptor. Because of steric hindrance from the crowded carbazole units, the carbazole units are markedly distorted from the dicyanobenzene plane with twist angles between 63° and 72°. The largely twisted linkage suppresses the coupling between the carbazole donors and the dicyanobenzene acceptor, leading to the spatially separated highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) at the carbazole units and the dicyanobenzene group. As a comparison, the molecular structure of TPA-NZP (Figure 1 b) is composed of triphenylamine (TPA), which acts as a donor, and naphtho [2,3-c] [1,2,5] thiadiazol (NZ) group, which serves as an acceptor. Compared to 4CzIPN, a slightly reduced twist angle of ≈53° is found between the donor and the acceptor in TPA-NZP, due to the relieved steric hindrance from the repulsion of adjacent hydrogen atoms between NZ and TPA groups. Such a decreased twist angle surely enhances the π-conjugation and electron delocalization between donor and acceptor. As expected, the HOMO of TPA-NZP is nearly delocalized over the whole molecular conjugated backbone, while the LUMO is only localized on the NZ group. Owing to the overlap between HOMO and LUMO determining the Δ E ST value (assuming a major transition confi guration HOMO→LUMO for single electron excitation), it can be concluded that the Recently, Adachi's group reported a series of experimental works on achieving signifi cantly enhanced electroluminescence (EL) quantum yield via a thermally activated delay fl uorescence (TADF) mechanism, in which the lowest triplet excite...

The structural and electronic properties of two heteroleptic iridium complexes Ir(dfppy)2(pic) (FIrpic) and Ir(dfppy)2(acac) (FIracac) have been investigated theoretically, where dfppy = 2-(2,4-difluorophenyl) pyridine, pic = picolinic acid, and acac = acetoylacetonate. The geometries of ground and excited states are optimized at PBE0/LANL2DZ and CIS/LANL2DZ levels, respectively. Time-dependent density functional theory (TDDFT) method is employed to explore the absorption and emission properties. In the ground state, the highest-occupied molecular orbital has a significant mixture of metal Ir(d) and dfppy(pi), the lowest-unoccupied orbital locates primarily on pi* of pic for FIrpic and pi* of dfppy for FIracac. The luminescence of each complex originates from the lowest triplet excited state, which is assigned to the mixing of metal-to-ligand charge transfer and intraligand charge transfer characters. The effects of ancillary ligands pic and acac on absorption and emission spectra are observed by analysis of TDDFT results. The connection between the nature of excited states and the behavior of the complexes with different ancillary ligands is elucidated.

It is demonstrated that a novel eutectic solution including 1,3,5-trioxane (TXE) and succinonitrile (SN) can be converted into solid-state polymer electrolyte (SPE) via in situ polymerization triggered by lithium difluoro(oxalato)borate (LiDFOB). It is worth noting that all the precursors (LiDFOB, TXE, and SN) of this novel SPE are totally solid and nonvolatile at room temperature, where, LiDFOB works as a lithium salt and an initiator simultaneously to avoid the introduction of impurity. It is noted that such SPE presents a considerable ionic conductivity of 1.14 × 10 −4 S cm −1 and a sufficiently wide electrochemical window of 4.5 V, which is significant for supporting the high-energy lithium batteries. In addition, this dedicatedly designed in situ polymerization is powerful to build kinetically favorable polymer-based protective layers on LiCoO 2 cathode and Li metal anode simultaneously, guaranteeing outstanding cycling stability (capacity retention of 88% after 200 cycles) of 4.3 V LiCoO 2 /lithium metal batteries at room temperature. More intriguingly, soft packed LiCoO 2 /SPE/Li metal batteries can still light a blue light emitting diode (LED) under the harsh conditions of being bent, cut, and stroked by a hammer, demonstrating excellent safety characteristics.

The resistance developed by life-threatening bacteria toward conventional antibiotics has become a major concern in public health. To combat antibiotic resistance, there has been a significant interest in the development of antimicrobial cationic polymers due to the ease of synthesis and low manufacturing cost compared to host-defense peptides (HDPs). Herein, we report the design and synthesis of amphiphilic polycarbonates containing primary amino groups. These polymers exhibit potent antimicrobial activity and excellent selectivity to Gram-positive bacteria, including multi-drug resistant pathogens. Fluorescence and TEM studies suggest that these polymers are likely to kill bacteria by disrupting bacterial membranes. These polymers also show low tendency to elicit resistance in bacteria. Their further development may lead to new antimicrobial agents combating drug-resistance.

New types of foldamer scaffolds are formidably challenging to design and synthesize, yet highly desirable as structural mimics of peptides/proteins with a wide repertoire of functions. In particular, the development of peptidomimetic helical foldamers holds promise for new biomaterials, catalysts, and drug molecules. Unnatural L-sulfono-γ-AApeptides were recently developed and shown to have potential applications in both biomedical and material sciences. However, D-sulfono-γ-AApeptides, the enantiomers of L-sulfono-γ-AApeptides, have never been studied due to the lack of high-resolution three-dimensional structures to guide structure-based design. Herein, we report the first synthesis and X-ray crystal structures of a series of 2:1 L-amino acid/D-sulfono-γ-AApeptide hybrid foldamers, and elucidate their folded conformation at the atomic level. Single-crystal X-ray crystallography indicates that this class of oligomers folds into well-defined right-handed helices with unique helical parameters. The helical structures were consistent with data obtained from solution 2D NMR, CD studies, and molecular dynamics simulations. Our findings are expected to inspire the structure-based design of this type of unique folding biopolymers for biomaterials and biomedical applications.