A series of new mixed-ligand copper(I) complexes [Cu(NN)-POP]BF 4 , where NN = 1,10-phenanthroline (phen; 1a), 2,9-dimethyl-phen (DMphen; 1b), 4,7-diphenyl-phen (DPpehn; 1c) and 2,2Ј-bipyridine (bpy; 2a), have been synthesized. Density functional theory (DFT) was applied to study the ground-and excited-state properties of these copper(I) complexes. The electronic structure variation is obtained by changing the substituted positions on the phenanthroline ligand. A time-dependent-DFT approach (TDDFT) was used to interpret the absorption and emission spectra in this system based on the optimized geometries at the B3LYP/ LANL2DZ and CIS/LANL2DZ levels of theory, respectively. The results show that the lowest-energy excitations of all

Molecular engineering of tetraazapentacene with different numbers of fluorine and chlorine substituents fine-tunes the frontier molecular orbitals, molecular vibrations, and π-π stacking for n-type organic semiconductors. Among the six halogenated tetraazapentacenes studied herein, the tetrachloro derivative (4Cl-TAP) in solution-processed thin-film transistors exhibits electron mobility of 14.9 ± 4.9 cm V s with a maximum value of 27.8 cm V s , which sets a new record for n-channel organic field-effect transistors. Computational studies on the basis of crystal structures shed light on the structure-property relationships for organic semiconductors. First, chlorine substituents slightly decrease the reorganization energy of the tetraazapentacene whereas fluorine substituents increase the reorganization energy as a result of fine-tuning molecular vibrations. Second, the electron transfer integral is very sensitive to subtle changes in the 2D π-stacking with brickwork arrangement. The unprecedentedly high electron mobility of 4Cl-TAP is attributed to the reduced reorganization energy and enhanced electron transfer integral as a result of modification of tetraazapentacene with four chlorine substituents.

The structures, ionization potentials (IPs), electron affinities (EAs), and HOMO-LUMO gaps (∆ H-L) of the oligomers are studied by the density functional theory with B3LYP functional. The lowest excitation energies (Egs) and the maximal absorption wavelength λabs of oligomers of polyfluorene (PF) and poly(2,7-fluorene-alt-co-5,7-dihydrodibenz[c,e]oxepin) (PFDBO) are studied employing the timedependent density functional theory (TD-DFT) and ZINDO. Band gaps and effective conjugation lengths of the corresponding polymers were obtained by extrapolating HOMO-LUMO gaps and the lowest excitation energies to infinite chain length. The IPs, EAs, and λ abs of the polymers were also obtained by extrapolating those of the oligomers to the inverse chain length equal to zero (1/n ) 0). For PFDBO, IPs and EAs are higher and the band gap is larger than those of PF's from the extrapolation. The outcome shows that the dramatically twisted structure of PFDBO in the seven-membered ring results in the decreased conjugation in the chain. These cause both the maximal absorption and emission wavelengths of PFDBO blue shift compared with PF.

Epithelial ovarian cancer (EOC) is the most common gynecologic malignancy. To identify the micro-ribonucleic acids (miRNAs) expression profile in EOC tissues that may serve as a novel diagnostic biomarker for EOC detection, the expression of 1722 miRNAs from 15 normal ovarian tissue samples and 48 ovarian cancer samples was profiled by using a quantitative real-time polymerase chain reaction (qRT-PCR) assay. A ten-microRNA signature (hsa-miR-1271-5p, hsa-miR-574-3p, hsa-miR-182-5p, hsa-miR-183-5p, hsa-miR-96-5p, hsa-miR-15b-5p, hsa-miR-182-3p, hsa-miR-141-5p, hsa-miR-130b-5p, and hsa-miR-135b-3p) was identified to be able to distinguish human ovarian cancer tissues from normal tissues with 97% sensitivity and 92% specificity. Two miRNA clusters of miR183-96-183 (miR-96-5p, and miR-182, miR183) and miR200 (miR-141-5p, miR200a, b, c and miR429) are significantly up-regulated in ovarian cancer tissue samples compared to those of normal tissue samples, suggesting theses miRNAs may be involved in ovarian cancer development.

The application of polyfluorenes in polymeric light-emitting diodes has been hampered because of the charge injection difficulties and the troublesome formation of a tailed emission band at long wavelengths (>500 nm) during device fabrication and operation, leading to both a color instability and reduced efficiency. The incorporation of the phenothiazine units has been proven to significantly enhance the hole injection and charge carrier balance and at the same time efficiently suppress the keto defect emission. In this contribution, we apply quantum-chemical techniques to investigate poly[10-(N-(2'-methyl)phenothiazine-3,7-diyl) and its fluorene copolymer poly[10-(N-(2'-methyl)phenothiazine-3,7-diyl)-co-alt-2,7-(9,9-dimethylfluorene)] (PFPTZ) and gain a detailed understanding the influence of phenothiazine units on the electronic and optical properties of fluorene derivatives. Density functional theory (DFT) and time-dependent DFT approaches are employed to study the neutral molecules, HOMO-LUMO gaps (Delta(H-L)), the lowest excitation energies (E(g)'s), positive and negative ions, as well as the IPs and EAs, focusing on the superiority of the electronic and optical properties attributed to the introduction of electron-donating moiety phenothiazine (PTZ) through comparing with pristine polyfluorene. The outcomes show that the highly nonplanar conformation of phenothiazine ring in the ground state preclude sufficiently close intermolecular interactions essential to forming aggregates or excimers. Furthermore, the HOMO energies lift about 0.4 eV, and thus, the IPs decrease about 0.3 eV in PFPTZ, suggesting the significant improved hole-accepting and transporting abilities, due to the electron-donating properties of phenothiazine ring by the presence of electron-rich sulfur and nitrogen heteroatoms and highly nonplanar characters, resulting in the enhanced performances in both efficiency and brightness compared with pristine polyfluorene. In addition, even though the introduction of electron-donating moiety PTZ onto fluorene leads to a slight bathochromic shift in absorption and emission spectra, the copolymer still exhibited strong blue emission.

Large Li2O2 aggregations can produce high‐capacity of lithium oxygen (Li‐O2) batteries, but the larger ones usually lead to less‐efficient contact between Li2O2 and electrode materials. Herein, a hierarchical cathode architecture based on different discharge characteristics of α‐MnO2 and Co3O4 is constructed, which can enable the embedded growth of large Li2O2 aggregations to solve this problem. Through experimental observations and first‐principle calculations, it is found that α‐MnO2 nanorod tends to form uniform Li2O2 particles due to its preferential Li+ adsorption and similar LiO2 adsorption energies of different crystal faces, whereas Co3O4 nanosheet tends to simultaneously generate Li2O2 film and Li2O2 nanosheets due to its preferential O2 adsorption and different LiO2 adsorption energies of varied crystal faces. Thus, the composite cathode architecture in which Co3O4 nanosheets are grown on α‐MnO2 nanorods can exhibit extraordinary synergetic effects, i.e., α‐MnO2 nanorods provide the initial nucleation sites for Li2O2 deposition while Co3O4 nanosheets provide dissolved LiO2 to promote the subsequent growth of Li2O2. Consequently, the composite cathode achieves the embedded growth of large Li2O2 aggregations and thus exhibits significantly improved specific capacity, rate capability, and cyclic stability compared with the single metal oxide electrode.

Density functional theory (DFT) is applied to analyze ground-and excited-state properties of the Re(I) halide bipyridine complex ReCl(CO) 3 (bpy) (1) and the related complexes ReCl(CO) 3 (5,5′-dibromo-bpy) (2), ReCl-(CO) 3 (4,4′-dimethyl-bpy) (3), and ReCl(CO) 3 (4,4′-dimethylformyl-bpy) (4) (where bpy ) 2,2′bipyridine). The electronic properties of the neutral molecules, in addition to the positive and negative ions, are studied using the B3LYP functional. Excited singlet and triplet states are examined using time-dependent DFT (TDDFT). The low-lying excited-state geometries are optimized at the ab initio configuration interaction singlets (CIS) level. As shown, the occupied orbitals involved in the transitions have a significant mixture of the metal Re and the group Cl, by the amount of metal 5d character which varies from 30 to 65%. The lowest unoccupied molecular orbital (LUMO) is a π* orbital of the ligand bpy for the series of molecules. The TDDFT result indicates that the absorption maxima are at relatively high energy and are mainly assigned to bpy-based ππ* transitions with somewhat metal-to-ligand charge transfer (MLCT) [d(Re) f π*(bpy)] and ligand-to-ligand charge transfer (LLCT) [p(Cl) f π*(bpy)] except for complex 3, in which this band is mainly assigned to mixed MLCT/LLCT, and overlaps bpy ππ* character. All the low-lying transitions are categorized as mixed MLCT/LLCT. The absorption bands are blue shifted when substituted by an electron-releasing group (-CH 3 ), and they are red shifted when substituted by an electron-withdrawing group (-Br or -COOCH 3 ). The luminescence of all complexes is assigned as a triplet metal/chlorine to bpy charge transfer (MLCT/LLCT).

Poly(fluorene)-type materials are widely used in polymer-based emitting devices. One of the drawbacks of light-emitting diodes based on polyfluorene derivatives is the injection of holes from the anode due to the high ionization potential (IP) of most derivatives. Substitution by electron-donating alkoxy substituents or by adding charge carriers on the conjugated polymer's backbone produces a remarkable influence on its electrical and optical properties. In this contribution, we apply quantum-chemical techniques to investigate a family of pi-conjugated polymers with substituted dimethoxy groups at the 3,6 positions of the fluorene ring, namely, poly(2,7-(3,6-dimethoxy-fluorene)(PDMOF), poly(2,7-(3,6-dimethoxy-fluorene)-co-alt-fluorene (PDMOFF), and poly(2,7-(3,6-dimeth-oxy-fluorene)-co-alt-2,5-thiophene (PDMOFT). The electronic properties of the neutral molecules, HOMO-LUMO gaps (Delta(H)(-)(L)), in addition to the positive and negative ions, are studied using the B3LYP functional. The lowest excitation energies (E(g)) and the maximal absorption wavelength lambda(abs) of PDMOF, PDMOFF, and PDMOFT are studied by employing time-dependent density functional theory (TD-DFT) and the ZINDO semiempirical method. The IP, EA, and E(g) values of each polymer were obtained by extrapolating those of the oligomers to the inverse chain length equal to zero ((1)/(n)() = 0). The influence of the presence of methoxy groups on the fluorene moiety on the ionization potential is especially emphasized. The outcomes show that the HOMO energies of these systems under study increase by about 0.4 eV and the IP values decrease by about 0.3 eV compared to those of the corresponding polyfluorene. Both effects result in a reduction of the energy barrier for the injection of holes in related polymeric light-emitting devices and should contribute to the enhancement of their performances. Because of the cooperation with thiophene in PDMOFT, which results in a good planar conformation, both the hole-creating and electron-accepting abilities are improved.