Stopped-Flow Kinetic Analysis of the Interaction of Cyclo[8]pyrrole with Anions

Karnas, Elizabeth,Kim, Sung Kuk,Johnson, Kenneth A.,Sessler, Jonathan L.,Ohkubo, Kei,Fukuzumi, Shunichi American Chemical Society 2010 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.132 No.46

<P>The on and off rates corresponding to the binding of two test anions (acetate, AcO<SUP>−</SUP>, and dihydrogen phosphate, H<SUB>2</SUB>PO<SUB>4</SUB><SUP>−</SUP>, studied as their tetrabutylammonium salts) to diprotonated cyclo[8]pyrrole have been determined in CH<SUB>3</SUB>CN using stopped-flow analyses carried out at various temperatures. For dihydrogen phosphate, this afforded the activation enthalpies and entropies associated with both off and on processes. The different dynamic behavior seen for these test anions underscores the utility of kinetic analyses as a possible new tool for the advanced characterization of anion receptors.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jacsat/2010/jacsat.2010.132.issue-46/ja107471x/production/images/medium/ja-2010-07471x_0001.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ja107471x'>ACS Electronic Supporting Info</A></P>

Ion-Mediated Electron Transfer in a Supramolecular Donor-Acceptor Ensemble

Park, Jung Su,Karnas, Elizabeth,Ohkubo, Kei,Chen, Ping,Kadish, Karl M.,Fukuzumi, Shunichi,Bielawski, Christopher W.,Hudnall, Todd W.,Lynch, Vincent M.,Sessler, Jonathan L. American Association for the Advancement of Scienc 2010 Science Vol.329 No.5997

<P>Ion binding often mediates electron transfer in biological systems as a cofactor strategy, either as a promoter or as an inhibitor. However, it has rarely, if ever, been exploited for that purpose in synthetic host-guest assemblies. We report here that strong binding of specific anions (chloride, bromide, and methylsulfate but not tetrafluoroborate or hexafluorophosphate) to a tetrathiafulvalene calix[4]pyrrole (TTF-C4P) donor enforces a host conformation that favors electron transfer to a bisimidazolium quinone (BIQ<SUP>2+</SUP>) guest acceptor. In contrast, the addition of a tetraethylammonium cation, which binds more effectively than the BIQ<SUP>2+</SUP> guest in the TTF-C4P cavity, leads to back electron transfer, restoring the initial oxidation states of the donor and acceptor pair. The products of these processes were characterized via spectroscopy and x-ray crystallography.</P>

Electroreduction and Acid–Base Properties of Dipyrrolylquinoxalines

Fu, Zhen,Zhang, Min,Zhu, Weihua,Karnas, Elizabeth,Mase, Kentaro,Ohkubo, Kei,Sessler, Jonathan L.,Fukuzumi, Shunichi,Kadish, Karl M. American Chemical Society 2012 The journal of physical chemistry. A, Molecules, s Vol.116 No.41

<P>The electroreduction and acid–base properties of dipyrrolylquinoxalines of the form H<SUB>2</SUB>DPQ, H<SUB>2</SUB>DPQ(NO<SUB>2</SUB>), and H<SUB>2</SUB>DPQ(NO<SUB>2</SUB>)<SUB>2</SUB> were investigated in benzonitrile (PhCN) containing 0.1 M tetra-<I>n</I>-butylammonium perchlorate (TBAP). This study focuses on elucidating the complete electrochemistry, spectroelectrochemistry, and acid–base properties of H<SUB>2</SUB>DPQ(NO<SUB>2</SUB>)<SUB><I>n</I></SUB> (<I>n</I> = 0, 1, or 2) in PhCN before and after the addition of trifluoroacetic acid (TFA), tetra-<I>n</I>-butylammonium hydroxide (TBAOH), tetra-<I>n</I>-butylammonium fluoride (TBAF), or tetra-<I>n</I>-butylammonium acetate (TBAOAc) to solution. Electrochemical and spectroelectrochemical data provide support for the formation of a monodeprotonated anion after disproportionation of a dipyrrolylquinoxaline radical anion produced initially. The generated monoanion is then further reduced in two reversible one-electron-transfer steps at more negative potentials in the case of H<SUB>2</SUB>DPQ(NO<SUB>2</SUB>) and H<SUB>2</SUB>DPQ(NO<SUB>2</SUB>)<SUB>2</SUB>. Electrochemically monitored titrations of H<SUB>2</SUB>DPQ(NO<SUB>2</SUB>)<SUB><I>n</I></SUB> with OH<SUP>–</SUP>, F<SUP>–</SUP>, or OAc<SUP>–</SUP> (in the form of TBA<SUP>+</SUP>X<SUP>–</SUP> salts) give rise to the same monodeprotonated H<SUB>2</SUB>DPQ(NO<SUB>2</SUB>)<SUB><I>n</I></SUB> produced during electroreduction in PhCN. This latter anion can then be reduced in two additional one-electron-transfer steps in the case of H<SUB>2</SUB>DPQ(NO<SUB>2</SUB>) and H<SUB>2</SUB>DPQ(NO<SUB>2</SUB>)<SUB>2</SUB>. Spectroscopically monitored titrations of H<SUB>2</SUB>DPQ(NO<SUB>2</SUB>)<SUB><I>n</I></SUB> with X<SUP>–</SUP> show a 1:2 stoichiometry and provide evidence for the production of both [H<SUB>2</SUB>DPQ(NO<SUB>2</SUB>)<SUB><I>n</I></SUB>]<SUP>−</SUP> and XHX<SUP>–</SUP>. The spectroscopically measured equilibrium constants range from log β<SUB>2</SUB> = 5.3 for the reaction of H<SUB>2</SUB>DPQ with TBAOAc to log β<SUB>2</SUB> = 8.8 for the reaction of H<SUB>2</SUB>DPQ(NO<SUB>2</SUB>)<SUB>2</SUB> with TBAOH. These results are consistent with a combined deprotonation and anion binding process. Equilibrium constants for the addition of one H<SUP>+</SUP> to each quinoxaline nitrogen of H<SUB>2</SUB>DPQ, H<SUB>2</SUB>DPQ(NO<SUB>2</SUB>), and H<SUB>2</SUB>DPQ(NO<SUB>2</SUB>)<SUB>2</SUB> in PhCN containing 0.1 M TBAP were also determined via electrochemical and spectroscopic means; this gave rise to log β<SUB>2</SUB> values ranging from 0.7 to 4.6, depending upon the number of nitro substituents present on the H<SUB>2</SUB>DPQ core. The redox behavior of the H<SUB>2</SUB>DPQ(NO<SUB>2</SUB>)<SUB><I>n</I></SUB> compounds of the present study were further analyzed through comparisons with simple quinoxalines that lack the two linked pyrrole groups, i.e., Q(NO<SUB>2</SUB>)<SUB><I>n</I></SUB> where <I>n</I> = 0, 1, or 2. It is concluded that the pyrrolic substituents play a critical role in regulating the electrochemical and spectroscopic features of DPQs.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jpcafh/2012/jpcafh.2012.116.issue-41/jp3074706/production/images/medium/jp-2012-074706_0017.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/jp3074706'>ACS Electronic Supporting Info</A></P>

Environmentally Responsive Threading, Dethreading, and Fixation of Anion-Induced Pseudorotaxanes

Gong, Han-Yuan,Rambo, Brett M.,Karnas, Elizabeth,Lynch, Vincent M.,Keller, Karin M.,Sessler, Jonathan L. American Chemical Society 2011 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.133 No.5

Disproportionation of Dipyrrolylquinoxaline Radical Anions via the Internal Protons of the Pyrrole Moieties

Fukuzumi, Shunichi,Mase, Kentaro,Ohkubo, Kei,Fu, Zhen,Karnas, Elizabeth,Sessler, Jonathan L.,Kadish, Karl M. American Chemical Society 2011 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.133 No.19

<P>Disproportionation of dipyrrolylquinoxaline radical anions occurs via hydrogen atom transfer from the pyrrole moiety to the quinoxaline moiety to produce monodeprotonated dipyrrolylquinoxaline anions and monohydrodipyrrolylquinoxaline anions. In contrast, simple quinoxaline radical anions without pyrrole moieties are stable, and disproportionation occurs only in the presence of external protons.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jacsat/2011/jacsat.2011.133.issue-19/ja200925e/production/images/medium/ja-2011-00925e_0002.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ja200925e'>ACS Electronic Supporting Info</A></P>

C₁₆ Saturated Fatty Acid Induced Autophagy in A549 Cells through Topoisomerase I Inhibition

Karna, Sandeep,Lim, Won Bong,Kim, Ji Sun,Kim, Sang Woo,Zheng, Hui,Bae, Kum Hue,Cho, Min Sung,Oh, Hee Kyun,Kim, Ok Su,Choi, Hong Ran,Kim, Ok Joon 'Scientific Research Publishing, Inc.' 2012 Food and nutrition sciences Vol.3 No.9

Collaboration Orientation, Peer Support and the Mediating Effect of Use of E-collaboration on Research Performance and Satisfaction

Karna, Darshana,Ko, Ilsang The Korea Society of Management Information System 2013 Asia Pacific Journal of Information Systems Vol.23 No.4

This study investigates the potential components for academic research collaboration, and the factors that make it possible to achieve higher academic productivity. The components include collaboration factors and a collaboration model. We use two major collaboration factors to develop a framework for understanding the mechanisms that influence academic research collaborations: motivational factors and mediating factors. Motivational factors include self-motivation and trust whereas mediating factors are collaboration orientation and peer support. We analyze the effect for use of e-collaboration with research performance, reward, and satisfaction with e-research output. A survey of academicians was conducted, and by using the factor analysis and the structural equation model with SPSS 20 AMOS, we illustrate the possible influence of these factors on research performance and satisfaction. We discovered that both motivational and mediating factors play important roles on the success of academic research. This study offers several implications for academicians. We develop a parsimonious research model, which is related to e-collaboration in academic research. This unique model offers academicians to achieve good publication output from the research team. The motivational factor, self-motivation and trust, are important factors which has received positive impact of mediating factor collaboration orientation and peer support. Our research sheds light on the crucial factors for use of e-collaboration which offer the ultimate effect on performance and satisfaction with e-research output. Satisfaction motivates people to work more and more on the field of their interest, thereby influencing the performance of academicians. Rewards should be distributed according to performance of the individual, which will motivate the person to become more enthusiastic for his work of interest. Our evidence suggests that in understating the collaborative process, one must account for the context in which the collaboration occurs, the motivation of the collaborators, the scope and nature of the project, the roles and activities undertaken, and interpersonal processes such as trust. Researchers' motivations for engaging in collaboration were both instrumental and intrinsic.

Nanotechnology in Meat Processing and Packaging: Potential Applications — A Review

Karna Ramachandraiah,한성구,진구복 아세아·태평양축산학회 2015 Animal Bioscience Vol.28 No.2

Growing demand for sustainable production, increasing competition and consideration of health concerns have led the meat industries on a path to innovation. Meat industries across the world are focusing on the development of novel meat products and processes to meet consumer demand. Hence, a process innovation, like nanotechnology, can have a significant impact on the meat processing industry through the development of not only novel functional meat products, but also novel packaging for the products. The potential benefits of utilizing nanomaterials in food are improved bioavailability, antimicrobial effects, enhanced sensory acceptance and targeted delivery of bioactive compounds. However, challenges exist in the application of nanomaterials due to knowledge gaps in the production of ingredients such as nanopowders, stability of delivery systems in meat products and health risks caused by the same properties which also offer the benefits. For the success of nanotechnology in meat products, challenges in public acceptance, economics and the regulation of food processed with nanomaterials which may have the potential to persist, accumulate and lead to toxicity need to be addressed. So far, the most promising area for nanotechnology application seems to be in meat packaging, but the long term effects on human health and environment due to migration of the nanomaterials from the packaging needs to be studied further. The future of nanotechnology in meat products depends on the roles played by governments, regulatory agencies and manufacturers in addressing the challenges related to the application of nanomaterials in food.

The Effect of Particle Size of Persimmon on Antioxidant Activities of Persimmon By-product Powders

Karna Ramachandraiah,Koo Bok Chin 한국식품영양과학회 2014 한국식품영양과학회 학술대회발표집 Vol.2014 No.10

Development of InDel markers to identify Capsicum disease resistance using whole genome resequencing

Karna, Sandeep,Ahn, Yul-Kyun The Korean Society of Plant Biotechnology 2018 식물생명공학회지 Vol.45 No.3

In this study, two pepper varieties, PRH1 (powdery mildew resistance line) and Saengryeg (powdery mildew resistance line), were resequenced using next generation sequencing technology in order to develop InDel markers. The genome-wide discovery of InDel variation was performed by comparing the whole-genome resequencing data of two pepper varieties to the Capsicum annuum cv. CM334 reference genome. A total of 334,236 and 318,256 InDels were identified in PRH1 and Saengryeg, respectively. The greatest number of homozygous InDels were discovered on chromosome 1 in PRH1 (24,954) and on chromosome 10 (29,552) in Saengryeg. Among these homozygous InDels, 19,094 and 4,885 InDels were distributed in the genic regions of PRH1 and Saengryeg, respectively, and 198,570 and 183,468 InDels were distributed in the intergenic regions. We have identified 197,821 polymorphic InDels between PRH1 and Saengryeg. A total of 11,697 primers sets were generated, resulting in the discovery of four polymorphic InDel markers. These new markers will be utilized in order to identify disease resistance genotypes in breeding populations. Therefore, our results will make a one-step advancement in whole genome resequencing and add genetic resource datasets in pepper breeding research.