Two New Phenolic Compounds from <i>Artemisia iwayomogi</i>

Yan, Xi&#x2010,Tao,Ding, Yan,Li, Wei,Sun, Ya&#x2010,Nan,Yang, Seo&#x2010,Young,Koh, Young&#x2010,Sang,Kim, Young&#x2010,Ho WILEY‐VCH Verlag 2014 Helvetica chimica acta Vol.97 No.2

<P><B>Abstract</B></P><P>Two new phenolic compounds, (<I>Z</I>)‐5′‐hydroxyjasmone 5′‐<I>O</I>‐{6″‐<I>O</I>‐[(<I>E</I>)‐caffeoyl]‐<I>β</I>‐<SMALL>D</SMALL>‐glucopyranoside} (<B>1</B>) and quercetin‐7‐<I>O</I>‐<I>β</I>‐<SMALL>D</SMALL>‐glucuronide methyl ester (<B>2</B>), along with ten known phenolic compounds, <B>3</B>–<B>12</B>, were isolated from the aerial parts of <I>Artemisia iwayomogi.</I> Their structures were elucidated by spectroscopic methods, including 1D‐ and 2D‐NMR, and HR‐ESI‐TOF‐MS techniques. The inhibitory effects of compounds <B>1</B>–<B>12</B> on the LPS‐stimulated production of IL‐12 p40, IL‐6, and TNF‐<I>α</I> in bone marrow‐derived dendritic cells were evaluated.</P>

<i>In Situ</i> Atomic-Scale Observation of Surface-Tension-Induced Structural Transformation of Ag-NiP_<i>x</i> Core-Shell Nanocrystals

Huang, Xing,Liu, Zhongqiang,Millet, Marie-Mathilde,Dong, Jichen,Plodine, Milivoj,Ding, Feng,Schlo&#x308,gl, Robert,Willinger, Marc-Georg American Chemical Society 2018 ACS NANO Vol.12 No.7

<P>The properties of nanocrystals are highly dependent on their morphology, composition, and structure. Tailored synthesis over these parameters is successfully applied for the production of nanocrystals with desired properties for specific applications. However, in order to obtain full control over the properties, the behavior of nanocrystals under external stimuli and application conditions needs to be understood. Herein, using Ag-NiP<SUB><I>x</I></SUB> nanocrystals as a model system, we investigate the structural evolution upon thermal treatment by <I>in situ</I> aberration-corrected scanning transmission electron microscopy. A combination of real-time imaging with elemental analysis enables the observation of the transformation from a Ag-NiP<SUB><I>x</I></SUB> core-shell configuration to a Janus structure at the atomic scale. The transformation occurs through dewetting and crystallization of the NiP<SUB><I>x</I></SUB> shell and is accompanied by surface segregation of Ag. Further temperature increase leads to a complete sublimation of Ag and formation of individual Ni<SUB>12</SUB>P<SUB>5</SUB> nanocrystals. The transformation is rationalized by theoretical modeling based on density functional theory calculations. Our model suggests that the transformation is driven by changes of the surface energy of NiP<SUB><I>x</I></SUB> and the interfacial energy between NiP<SUB><I>x</I></SUB> and Ag. The direct observation of atomistic dynamics during thermal-treatment-induced structural modification will help to understand more complex transformations that are induced by aging over time or the interaction with a reactive gas phase in applications such as catalysis.</P> [FIG OMISSION]</BR>

Push–Pull Type Oligo(<i>N</i>-annulated perylene)quinodimethanes: Chain Length and Solvent-Dependent Ground States and Physical Properties

Zeng, Zebing,Lee, Sangsu,Son, Minjung,Fukuda, Kotaro,Burrezo, Paula Mayorga,Zhu, Xiaojian,Qi, Qingbiao,Li, Run-Wei,Navarrete, Juan T. Lo&#x301,pez,Ding, Jun,Casado, Juan,Nakano, Masayoshi,Kim, Dongho American Chemical Society 2015 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.137 No.26

<P>Research on stable open-shell singlet diradicaloids recently became a hot topic because of their unique optical, electronic, and magnetic properties and promising applications in materials science. So far, most reported singlet diradicaloid molecules have a symmetric structure, while asymmetric diradicaloids with an additional contribution of a dipolar zwitterionic form to the ground state were rarely studied. In this Article, a series of new push pull type oligo(N-annulated perylene)quinodimethanes were synthesized. Their chain length and solvent-dependent ground states and physical properties were systematically investigated by various experimental methods such as steady-state and transient absorption, two-photon absorption, X-ray crystallographic analysis, electron spin resonance, superconducting quantum interference device, Raman spectroscopy, and electrochemistry. It was found that with extension of the chain length, the diradical character increases while the contribution of the zwitterionic form to the ground state becomes smaller. Because of the intramolecular charge transfer character, the physical properties of this push pull system showed solvent dependence. In addition, density functional theory calculations on the diradical character and Hirshfeld charge were conducted to understand the chain length and solvent dependence of both symmetric and asymmetric systems. Our studies provided a comprehensive understanding on the fundamental structure and environment property relationships in the new asymmetric diradicaloid systems.</P>

Root hair‐specific expansins modulate root hair elongation in rice

ZhiMing, Yu,Bo, Kang,XiaoWei, He,ShaoLei, Lv,YouHuang, Bai,WoNa, Ding,Ming, Chen,Hyung&#x2010,Taeg, Cho,Ping, Wu Blackwell Publishing Ltd 2011 The Plant journal Vol.66 No.5

<P><B>Summary</B></P><P>Root hair growth requires intensive cell‐wall modification. This study demonstrates that root hair‐specific expansin As, a sub‐clade of the cell wall‐loosening expansin proteins, are required for root hair elongation in rice (<I>Oryza sativa</I> L.). We identified a gene encoding <I>EXPA17</I> (<I>OsEXPA17</I>) from a rice mutant with short root hairs. Promoter::reporter transgenic lines exhibited exclusive <I>OsEXPA17</I> expression in root hair cells. The OsEXPA17 mutant protein (OsexpA17) contained a point mutation, causing a change in the amino acid sequence (Gly104→Arg). This amino acid alteration is predicted to disrupt a highly conserved disulfide bond in the mutant. Suppression of <I>OsEXPA17</I> by RNA interference further confirmed requirement for the gene in root hair elongation. Complementation of the <I>OsEXPA17</I> mutant with other root hair EXPAs (OsEXPA30 and Arabidopsis EXPA7) can restore root hair elongation, indicating functional conservation of these root hair EXPAs in monocots and dicots. These results demonstrate that members of the root hair EXPA sub‐clade play a crucial role in root hair cell elongation in Graminaceae.</P>

Toward Tetraradicaloid: The Effect of Fusion Mode on Radical Character and Chemical Reactivity

Hu, Pan,Lee, Sangsu,Herng, Tun Seng,Aratani, Naoki,Gonc&#x327,alves, The&#x301,o P.,Qi, Qingbiao,Shi, Xueliang,Yamada, Hiroko,Huang, Kuo-Wei,Ding, Jun,Kim, Dongho,Wu, Jishan American Chemical Society 2016 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.138 No.3

<P>Open-shell singlet diradicaloids display unique electronic, nonlinear optical, and magnetic activity and could become novel molecular materials for organic electronics, photonics, and spintronics. However, design and synthesis of diradicaloids with a significant polyradical character is a challenging task for chemists. In this Article, we report our efforts toward a tetraradicaloid system. A series of potential tetraradicaloids by fusion of two p-quinodimethane (p-QDM) units with naphthalene or benzene rings in different modes were synthesized. Their model compounds containing one p-QDM moiety were also prepared and compared. Their ground-state structures, physical properties, and chemical reactivity were systematically investigated by various experimental methods such as steady-state and transient absorption, two-photon absorption, X-ray crystallographic analysis, electron spin resonance, superconducting quantum interference device, and electrochemistry, assisted by density functional theory calculations. It was found that their diradical and tetraradical characters show a clear dependence on the fusion mode. Upon the introduction of more five-membered rings, the diradical characters greatly decrease. This difference can be explained by the pro-aromaticity/antiaromaticity of the molecules as well as the intramolecular charge transfer. Our comprehensive studies provide a guideline for the design and synthesis of stable open-shell singlet polycyclic hydrocarbons with significant polyradical characters.</P>

Stable Tetrabenzo-Chichibabin’s Hydrocarbons: Tunable Ground State and Unusual Transition between Their Closed-Shell and Open-Shell Resonance Forms

Zeng, Zebing,Sung, Young Mo,Bao, Nina,Tan, Davin,Lee, Richmond,Zafra, Jose&#x301,L.,Lee, Byung Sun,Ishida, Masatoshi,Ding, Jun,Lo&#x301,pez Navarrete, Juan T.,Li, Yuan,Zeng, Wangdong,Kim, Dongho,Huang American Chemical Society 2012 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.134 No.35

<P>Stable open-shell polycyclic aromatic hydrocarbons (PAHs) are of fundamental interest due to their unique electronic, optical, and magnetic properties and promising applications in materials sciences. Chichibabin’s hydrocarbon as a classical open-shell PAH has been investigated for a long time. However, most of the studies are complicated by their inherent high reactivity. In this work, two new stable benzannulated Chichibabin’s hydrocarbons <B>1-CS</B> and <B>2-OS</B> were prepared, and their electronic structure and geometry in the ground state were studied by various experiments (steady-state and transient absorption spectra, NMR, electron spin resonance (ESR), superconducting quantum interference device (SQUID), FT Raman, X-ray crystallographic etc.) and density function theory (DFT) calculations. <B>1-CS</B> and <B>2-OS</B> exhibited tunable ground states, with a closed-shell quinoidal structure for <B>1-CS</B> and an open-shell biradical form for <B>2-OS</B>. Their corresponding excited-state forms <B>1-OS</B> and <B>2-CS</B> were also chemically approached and showed different decay processes. The biradical <B>1-OS</B> displayed an unusually slow decay to the ground state (<B>1-CS</B>) due to a large energy barrier (95 ± 2.5 kJ/mol) arising from severe steric hindrance during the transition from an orthogonal biradical form to a butterfly-like quinoidal form. The quick transition from the quinoidal <B>2-CS</B> (excited state) to the orthogonal biradicaloid <B>2-OS</B> (ground state) happened during the attempted synthesis of <B>2-CS</B>. Compounds <B>1-CS</B> and <B>2-OS</B> can be oxidized into stable dications by FeCl<SUB>3</SUB> and/or concentrated H<SUB>2</SUB>SO<SUB>4</SUB>. The open-shell <B>2-OS</B> also exhibited a large two-photon absorption (TPA) cross section (760 GM at 1200 nm).</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jacsat/2012/jacsat.2012.134.issue-35/ja3050579/production/images/medium/ja-2012-050579_0017.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ja3050579'>ACS Electronic Supporting Info</A></P>

Reduction of the thermocline feedback associated with mean SST bias in ENSO simulation

Xiang, Baoqiang,Wang, Bin,Ding, Qinghua,Jin, Fei&#x2013,Fei,Fu, Xiouhua,Kim, Hyung-Jin Springer-Verlag 2012 Climate dynamics Vol.39 No.6

Octazethrene and Its Isomer with Different Diradical Characters and Chemical Reactivity: The Role of the Bridge Structure

Hu, Pan,Lee, Sangsu,Park, Kyu Hyung,Das, Soumyajit,Herng, Tun Seng,Gonc&#x327,alves, The&#x301,o P.,Huang, Kuo-Wei,Ding, Jun,Kim, Dongho,Wu, Jishan American Chemical Society 2016 Journal of organic chemistry Vol.81 No.7

<P>The fundamental relationship between structure and diradical character is important for the development of open-shell diradicaloid-based materials. In this work, we synthesized two structural isomers bearing a 2,6-naphthoquinodimethane or a 1,5-naphthoquinodimethane bridge and demonstrated that their diradical characters and chemical reactivity are quite different. The mesityl-or pentafluorophenyl-substituted octazethrene derivatives <B>OZ-M/OZ-F</B> and their isomer <B>OZI-M</B> (with mesityl substituents) were synthesized via an intramolecular Friedel–Crafts alkylation followed by oxidative dehydrogenation strategy from the key building blocks <B>4</B> and <B>11</B>. Our detailed experimental and theoretical studies showed that both isomers have an open-shell singlet ground state with a remarkable diradical character (<I>y</I><SUB>0</SUB> = 0.35 and 0.34 for <B>OZ-M</B> and <B>OZ-F</B>, and <I>y</I><SUB>0</SUB> = 0.58 for <B>OZI-M</B>). Compounds <B>OZ-M</B> and <B>OZ-F</B> have good stability in an ambient environment, while <B>OZI-M</B> has high reactivity and can be easily oxidized to a dioxo product <B>15</B>, which can be correlated to their different diradical characters. Additionally, we investigated the physical properties of <B>OZ-M</B>, <B>OZ-F</B>, and <B>15</B>.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/joceah/2016/joceah.2016.81.issue-7/acs.joc.6b00172/production/images/medium/jo-2016-00172x_0011.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/jo6b00172'>ACS Electronic Supporting Info</A></P>

Fluorenyl Based Macrocyclic Polyradicaloids

Lu, Xuefeng,Lee, Sangsu,Hong, Yongseok,Phan, Hoa,Gopalakrishna, Tullimilli Y.,Herng, Tun Seng,Tanaka, Takayuki,Sandoval-Salinas, Mari&#x301,a Eugenia,Zeng, Wangdong,Ding, Jun,Casanova, David,Osuka, At American Chemical Society 2017 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.139 No.37

<P>Synthesis of stable open-shell polyradicaloids including control of intramolecular spin-spin interactions is a challenging topic in organic chemistry and materials science. Herein, we report the synthesis and physical characterization of two series of fluorenyl based macrocyclic polyradicaloids. In one series (FR-MCn, n = 4-6), the fluorenyl radicals are directly linked at 3,6-positions; whereas in the other series (MC-FnAn, n = 3-5), an additional ethynylene moiety is inserted between the neighboring fluorenyl units. To access stable macrocyclic polyradicaloids, three synthetic methods were developed. All of these stable macrocycles can be purified by normal silica gel column chromatography under ambient conditions. In all cases, moderate polyradical characters were calculated by restricted active space spin-flip method due to the moderate intramolecular antiferromagnetic spin-spin interactions. The excitation energies from the low-spin ground state to the lowest high-spin excited state were evaluated by superconducting quantum interference device measurements. Their physical properties were also compared with the respective linear fluorenyl radical oligomers (FR-n, n = 3-6). It is found that the geometry, i.e., the distortional angle and spacer (w or w/o ethynylene) between the neighboring fluorenyl units, has significant effect on their polyradical character, excitation energy, one-photon absorption, two-photon absorption and electrochemical properties. In addition, the macrocyclic tetramers FR-MC4 and MC-F4A4 showed global antiaromatic character due to cyclic pi-conjugation with 36 and 44 pi-electrons, respectively.</P>

An exact algorithm for minimum CDS with shortest path constraint in wireless networks

Ding, L.,Gao, X.,Wu, W.,Lee, W.,Zhu, X.,Du, D. Z. Springer Science + Business Media 2011 Optimization letters Vol.5 No.2