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This paper proposes a single-stage single-ended primary inductor converter (SEPIC) converter circuit, which is applied to the organic light-emitting diodes (OLED) driver circuit. The circuit proposed in this paper replaces the output Schottky diode from the original SEPIC with a power switch. Deadtime is added to prevent the on-state overlapping of two switches with zero voltage switching (ZVS), and the circuit operates in triangular current mode. The digital control methods are maximum power point tracking and frequency modulation using a battery to supply the converter and illuminate the OLED at night. Finally, a prototype is implemented to show the feasibility under the DC input voltage range of 10–40 V. The DC output is 12 V/1 A/12 W, and the conversion efficiency is up to 96.3%.

Despite the widespread success in the functionalization of C(sp2)−H bonds, the deliberate functionalization of C(sp3)−H bonds in a highly site‐ and stereoselective manner remains a longstanding challenge. Herein, we report an iridium/aluminum cooperative catalytic system that enables the β‐selective C−H borylation of saturated cyclic amines and lactams. Furthermore, we have accomplished an enantioselective variant using binaphthol‐derived chiral aluminum catalysts to forge C−B bonds with high levels of stereocontrol. Computational studies suggest that the formation of a Lewis pair with the substrates is crucial to lower the energy of the transition state for the rate‐determining reductive elimination step. [ABSTRACT FROM AUTHOR]

An increasing number of chemists have focused on the investigations of two-electron/multicenter bond (2e/mc) that was first introduced to describe the structure of radical dimers. In this work, the dimerization of two isoelectronic radicals, triazaphenalenyl (TAP) and hexaazaphenalenyl (HAP) has been investigated in theory. Results show TAP2 is a stable dimer with stronger 2e/12c bond and larger interaction energy, while HAP2 is a less stable dimer with larger diradical character. Interestingly, the ultraviolet-visible absorption spectra suggest that the dimerization induces a longer wavelength absorption in visible area, which is dependent on the strength of dimerization. Significantly, the amplitude of second hyperpolarizability (γyyyy) of HAP2 is 1.36 × 106 a.u. that is larger than 7.79 × 104 a.u. of TAP2 because of the larger diradical character of HAP2. Therefore, the results indicate that the strength of radical dimerization can be effectively detected by comparing the magnitude of third order non-linear optical response, which is beneficial for further theoretical and experimental studies on the properties of complexes formed by radical dimerization. [ABSTRACT FROM AUTHOR]

An external electric field (EEF), as a metal-free catalyst, catalyzing the Markovnikov hydrosilylation of styrene was studied for the first time. As compared to the field-free situation, the barrier height was almost halved upon the application of EEF with a field strength of 180 × 10−4 a.u. in the direction perpendicular to the "bond axis". Therefore, the use of EEF not only resolved the questions of the separation of homogeneous catalysts from the reaction mixture, but also facilitated the reaction by decreasing its barriers. Furthermore, we found that the lower the energy of the transition state (TSX) and the higher the energy of the HOMO of the reactant (R1′), the lower the barrier height of hydrosilylation. Hopefully, this study can provide guidance toward experiments involving an external electric field. [ABSTRACT FROM AUTHOR]

N-Heterocyclic carbene (NHC) ligands effective for the cross-coupling of nitroarenes were identified. A rational design of the NHC ligand structures enabled significant reduction of catalyst loadings compared with the previous system employing BrettPhos as a phosphine ligand. Experimental and theoretical studies to compare these ligands gave some insights into high activity of the newly developed NHC ligands. [ABSTRACT FROM AUTHOR]

Stable phenalenyl (PLY) radical π‐dimers still play an important role for new multifunctional materials owing to their intriguing molecular structure and unusual pancake π–π bonding mode. Herein, we design a new biphenalenyl biradicaloid (1) consisting of two PLYs and one benzene ring linkage tethered by single bonds, which presents an open‐shell character. Further, three π‐dimers (a1, b1, and c1) combined with 1 and conventional biphenalenyl biradicaloid (a, b, and c), which are capable of forming two staggered PLY dimers, exhibiting a short interlayer distance between the monomers. Interestingly, the analysis of the frontier molecular orbital reveals that two bonding orbitals, namely, the two highest occupied molecular orbitals (HOMO and HOMO−1) are doubly occupied. The results reveal that three π‐dimers display two parallel pancake bonds. Moreover, they have small diradical and tetraradical characters, large interaction energies, and strong aromaticity, which indicate the stability of these π‐dimers. The present work creates a new class of strong pancake bonding and might be utilized in devising an array of materials. Pancake bonds: A biphenalenyl biradicaloid that consists of two phenalenyls and one benzene ring linkage (1) were designed for building two parallel stacked π–π bonds. Interestingly, three π‐dimers (a1, b1, and c1) combined with 1 and conventional biphenalenyl biradicaloid (a, b, and c), which exhibit unusual two parallel pancake‐shaped π–π bonding. [ABSTRACT FROM AUTHOR]

Abstract: In novel superatom chemistry, it is very attractive that all‐metal clusters can mimic the behaviors of nonmetal atoms and simple nonmetal molecules. Wizardly all‐metal halogen‐like superatom Al13 with 2P5 sub shell (corresponding to the 3p5 of chlorine) is the most typical example. In contrast, how to mimic the behaviors of magnetic transition‐metal atom using all‐nonmetal cluster is an intriguing challenge for superatom chemistry. In response to this based on human intuition, using quantum chemistry methods and extending jellium model from metal cluster to all‐nonmetal cluster, we have found out that all‐nonmetal octahedral B6 cluster with characteristic jellium electron configuration 1S21P62S21D8 in the triplet ground state can mimic the behaviors of transition‐metal Ni atom with electron configuration 3s23p64s23d8 in electronic configuration, physics and chemistry. Interestingly, the characteristic order of 1S1P2S1D for the B6 nonmetal cluster with short B‐B lengths is different from that of the traditional jellium model—1S1P1D2S for metal clusters with long M‐M lengths, which exhibits a novel size effect of nonmetal cluster on jellium orbital ordering. Based on the jellium electron configuration, the B6 with the spin moment value of 2μB is a new all‐nonmetal transition‐metal nickel‐like superatom exhibiting a new kind of all‐nonmetal magnetic superatom. Finding the application of the all‐nonmetal magnetic superatom, we encapsulate the magnetic superatom B6 inside fully hydrogenated fullerene forming a clathrate B6@C60H60 with the spin moment value of 2μB. As the C60H60 cage as a polymerization unit can conserve the spin moment of endohedral B6, the clathrate B6@C60H60 is a new all‐nonmetal magnetic superatom building block. Naturally, magnetic superatom structures of the B6 and B6@C60H60 may be metastable. [ABSTRACT FROM AUTHOR]

A series of diradical π-dimers 2 with interesting pancake-shaped 2e/24c π–π bonding character were designed and investigated based on the famous phenalenyl (PLY) π-dimer with 2e/12c π–π bonding character. The position of stronger interaction between two layers of radicals was found by the Wiberg bond index (WBI) maximum component. Further, the different contributions of the interaction energy were analyzed quantitatively by energy decomposition analysis (EDA). Among these new diradical π-dimers, 2180 has the smallest layer distance and the largest interaction between two layers of radicals. The unusual PLY analogues can provide new insights into the unique features of two-electron/multicenter (2e/mc) π–π bonding. [ABSTRACT FROM AUTHOR]

All-metal electride molecules, CuAg@Ca7M (M = Be, Mg and Ca), have been designed and researched in theory for the first time. In these molecules, a pull–push electron relay occurs. Unusually, the all-metal polyanions of fourfold negatively charged [Cu–Ag–Be/Mg]4− and [Cu–Ag]4− with 4 extra electrons gained from Ca atoms push the remaining valence electrons of the Ca atoms forming the multi-excess electrons (Ne = 10/12). Therefore, these molecules can be described as salt-like [(Ca2+)7(CuAgM)4−] + 10e− (M = Be and Mg) and [(Ca2+)8(CuAg)4−] + 12e−. In these salt-like molecules, there are extraordinary covalent bonding modes, which include 2c–2e/3c–2e σ-bonding in the polyanions and the Ca2+ cations sharing the diffuse multi-excess electrons. For an intriguing nonlinear optical (NLO) response, these all-metal electride molecules display large electronic first hyperpolarizabilities (β0), thus a new class of NLO molecules, all-metal electride NLO molecules, emerge. Moreover, it is also found that manipulating the atomic number and position of M is a new strategy to enhance β0. As a result, CuAg@Ca7Mg(1) exhibits a considerable β0 (1.43 × 104 au), which is 16 times the β0 sum of two isolated CuAg and Ca7Mg(1) subunits, and this deeply reveals the fundamental origin of the considerable β0, namely, the multi-excess electrons generated by the subunit interaction. These all-metal electride molecules have the infrared (IR) transparent region of 1.3–6 μm, and hence are new IR NLO molecules. In addition the electronic contribution, β0, the large effects of vibrations on the static first hyperpolarizabilities of these all-metal electride molecules are also estimated. Thus, this study opens the new research field of all-metal electride IR NLO molecules. [ABSTRACT FROM AUTHOR]

Two pillared-layer metal-organic frameworks (MOFs; PMOF-55 and NH2-PMOF-55) based on 1,2,4-triazole and terephthalic acid (bdc)/NH2-bdc ligands were assembled and display framework stabilities, to a certain degree, in both acid/alkaline solutions and toward water. They exhibit high CO2 uptakes and selective CO2/N2 adsorption capacities, with CO2/N2 selectivity in the range of 24-27, as calculated by the ideal adsorbed solution theory method. More remarkably, the site and interactions between the host network and the CO2 molecules were investigated by single-crystal X-ray diffraction, which showed that the main interaction between the CO2 molecules and PMOF-55 is due to multipoint supramolecular interactions of CH⋅⋅⋅O, C⋅⋅⋅O, and O⋅⋅⋅O. Amino functional groups were shown to enhance the CO2 adsorption and identified as strong adsorption sites for CO2 by X-ray crystallography. [ABSTRACT FROM AUTHOR]

Three molecules HArF@BNNT(5,0), HArF@BNNT(6,0), and HArF@BNNT(7,0) have been formed by HArF encapsulated in boron nitride nanotubes (BNNTs) with different sizes. Due to the interaction between the HArF and the BNNTs, the HAr bond lengths are in a decrease trend, while the ArF bond lengths are in an increase trend compared with those of HArF. To investigate the nature of the interaction between H and Ar and the interaction between Ar and F, the quantum theory of 'atoms in molecules' was carried out. The Laplacian (▿2 ρb) values of HAr suggest that the covalent interaction plays a key role in the H-Ar interaction. For ArF, the results indicate that the Ar-F interaction has a dominant noncovalent character. Moreover, the results obtained from the ratio of the kinetic-energy density ( Gb) and the potential-energy density ( Vb) (− Gb/ Vb) and the total energy density ( Hb) are in good agreement with that of ▿2 ρb values. In addition, the results of natural bond orbital charge and electron density difference between the HArF and BNNTs show that less electrons transfer away from the HArF to BNNTs with the gradual increase in the diameters of the BNNTs. © 2014 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Möbius strip has attracted extensive interest due to its one-side structure, special physical and chemical properties. A new extended porphyrin with Möbius structure has been synthesized (Stępień et al., Angew. Chem. Int. Ed. 2007, 46, 7869). In this work, an electron is injected into Möbius to form Möbius anion. For Möbius, four methods (B3LYP, BHandHLYP, CAM-B3LYP, and LC-BLYP) obtain the similar first hyperpolarizability ( β0). However, for Möbius anion, four methods obtain very different β0 values (ranging from 9.85 × 103 to 8.33 × 105 au). Moreover, the β0 values of Möbius anion are larger than those of Möbius. Why? The considerable variation (ranging from 0.8162 to 1.7630) of spin contamination ( S2) of open-shell Möbius anion captures our attention. To probe the relationship between S2 and β0, the β0 values of Möbius anion were calculated using 23 methods. Interestingly, the Hartree-Fock (HF) composition increases from 0 to 50, the S2 value ranges from 0.7522 to 1.3372, and the β0 value increases from 4.3 × 103 to 7.36 × 104 au. Further, methods are 'dissected' to investigate the effect of HF composition on the S2. © 2014 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Carbon-boron-nitride heteronanotubes have attracted much interest owing to their adjustable properties and wide applications in many fields. In this work, the structures and first hyperpolarizabilities ( β0) of a series of HA- n and isoelectronic PA- n heteronanotubes are investigated, in which HA- n is composed of a helical C segment and BN segment, and PA- n is composed of an arc C segment and BN segment. Interestingly, the helix C segment in HA-9 leads to a fascinating long-range charge-transfer character. As a result, the β0 value of HA-9 is 1.80×104 a.u., which is much larger than that of PA-9 (4.99×103 a.u.). Significantly, the β0 value of the C segment in HA-9 is 1.72×104 a.u., whereas that of the BN segment in HA-9 is much smaller (7.48×102 a.u.). In this context, the larger β0 value of HA-9 is essentially induced by the helix topological effect of the C segment. It is our expectation that this new knowledge about heteronanotubes might provide more ideas for further exploration of sp2-hybridized carbon segments with special topologies. [ABSTRACT FROM AUTHOR]

Nonlinear optical (NLO) materials are the smartest materials of the era, and have the ability to generate new electromagnetic fields with changed frequencies, phases, and other physical properties. Recently, many cutting edge research reports have been focused on NLO materials especially on those which are composed of sp2 hybridized carbon nanostructures. As the carbon nanostructures are composed of abundant π-electrons and have significant delocalization, these are potential candidates for modern NLO materials. Generally, sp2 hybridized carbon nanostructures can be divided into zero-dimensional fullerenes, one-dimensional nanotubes and two-dimensional graphene nanoribbons and quantum dots etc. These dimensionally different carbon nanomaterials are promising candidates for a wide range of applications in next-generation nanotechnologies. In present feature article, we first briefly explain a theoretical structure–NLO property relationship based on perturbation theory and then elucidate the crucial factors to control the NLO responses. We put together the different random investigations of sp2 hybridized carbon nanostructures for NLO application by highlighting the importance of their several structural designs to tune NLO amplitudes. Furthermore, we make a comparative and updated analysis of the NLO properties of dimensionally different sp2 hybridized carbon nanomaterials i.e. fullerenes, carbon nanotubes, and graphene nanoribbons and quantum dots. Finally, we make a brief discussion about different aspects and opportunities to use the sp2 hybridized carbon nanomaterials as high performance NLO materials of the future. This review is a focused perspective based on different updated quantum chemical investigations about fullerenes, nanotubes and graphene nanoribbons and quantum dots for their possible use in nonlinear optical applications. [ABSTRACT FROM AUTHOR]

In this work, we add different strength of external electric field ( Eext) along molecule axis (Z-axis) to investigate the electric field induced effect on HArF structure. The H-Ar bond is the shortest at Eext = −189 × 10−4 and the Ar-F bond show shortest value at Eext = 185 × 10−4 au. Furthermore, the wiberg bond index analyses show that with the variation of HArF structure, the covalent bond H-Ar shows downtrend (ranging from0.79 to 0.69) and ionic bond Ar-F shows uptrend (ranging from 0.04 to 0.17). Interestingly, the natural bond orbital analyses show that the charges of F atom range from −0.961 to −0.771 and the charges of H atoms range from 0.402 to 0.246. Due to weakened charge transfer, the first hyperpolarizability (βtot) can be modulated from 4078 to 1087 au. On the other hand, make our results more useful to experimentalists, the frequency-dependent first hyperpolarizabilities were investigated by the coupled perturbed Hartree-Fork method. We hope that this work may offer a new idea for application of noble-gas hydrides. © 2013 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]