A benzocrown-6-calix[4]arene methacrylate copolymer: Selective extraction of caesium ions from a multi-component system

Rambo, Brett M.,Kim, Sung Kuk,Kim, Jong Seung,Bielawski, Christopher W.,Sessler, Jonathan L. Royal Society of Chemistry 2010 Chemical Science Vol.1 No.6

<P>The synthesis and extraction properties of a copolymer comprised of a 10:1 molar ratio of methyl methacrylate (MMA) and a methacrylate functionalized benzocrown-6-calix[4]arene are reported. Under aqueous-dichloromethane liquid–liquid extraction conditions, the copolymer displayed an enhanced selectivity for caesium over sodium and potassium (in the form of their picrate salts) as compared to an appropriate small molecule analogue. Further, the copolymer was capable of removing caesium nitrate from aqueous solution in the presence of various other anionic (<I>e.g.</I>, F<SUP>−</SUP>, Cl<SUP>−</SUP>, and SO<SUB>4</SUB><SUP>−</SUP>) and cationic species (<I>e.g.</I>, K<SUP>+</SUP> and Na<SUP>+</SUP>). The ability of this polymeric system to extract inorganic caesium salts into dichloromethane from aqueous media scaled with the relative hydration energies (Δ<SUB>hyd</SUB>G°) of each anion studied (<I>i.e.</I>, NO<SUB>3</SUB><SUP>−</SUP> > Br<SUP>−</SUP> ≫ Cl<SUP>−</SUP> or F<SUP>−</SUP>).</P> <P>Graphic Abstract</P><P>The synthesis and extraction properties of a copolymer comprised of a 10:1 molar ratio of methyl methacrylate (MMA) and a methacrylate functionalized benzocrown-6-calix[4]arene are reported. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c0sc00396d'> </P>

The “Texas-Sized” Molecular Box: A Versatile Building Block for the Construction of Anion-Directed Mechanically Interlocked Structures

Rambo, Brett M.,Gong, Han-Yuan,Oh, Moonhyun,Sessler, Jonathan L. American Chemical Society 2012 Accounts of chemical research Vol.45 No.8

<P>Over the last two decades, researchers have focused on the synthesis and development of mechanically interlocked molecules (MIMs). The intramolecular motion of mechanical bonds and the ability to induce this effect with the choice of the proper external stimuli has prompted the development of macromolecular systems that possess the ability to “perform work” at the molecular level. Currently, researchers are working to incorporate interlocked species into complex structural systems, such as molecular frameworks and nanoparticles, and to create ever more elegant noncovalent architectures. This effort provides an incentive to generate new building blocks for the construction of MIMs. In this Account, we describe progress in the development of a new cationic building block inspired by the “blue box” of Stoddart and collaborators.</P><P>The blue box (cylcobis(paraquat-<I>p</I>-phenylene) or CBPQT<SUP>4+</SUP>) is a tetracationic, electron-deficient macrocycle widely recognized for its role in the construction of MIMs. This venerable receptor displays a high affinity for a variety of π-donor guests, and researchers have used them to construct a wide range of molecular and supramolecular structures, including rotaxanes, catenanes, pseudorotaxanes, polypseudorotaxanes, pseudo[<I>n</I>]polyrotaxanes, and electrochemically switchable molecules. To date, several synthetic analogues of the basic CBPQT<SUP>4+</SUP> structure have been reported, including systems containing biphenylene linkers and chiral tetracationic cyclophanes. However, researchers have not yet fully generalized the promise of the blue box.</P><P>In this Account, we chronicle the development of a larger, more flexible tetracationic macrocycle, referred to as the “Texas-sized” molecular box. To highlight its relatively increased size and to distinguish it from CBPQT<SUP>4+</SUP>, we have chosen to color this new receptor burnt orange. The Texas-sized box (cyclo[2](2,6-di(1<I>H</I>-imidazol-1-yl)pyridine)[2](1,4-dimethylenebenzene), <B>1</B><SUP>4+</SUP>·4PF<SUB>6</SUB><SUP>–</SUP>) acts as a dynamic molecular receptor that displays an ability to adjust its shape and conformation to accommodate anionic guests of different size and charge within its central core. The use of different guests can favor different binding modes and promote the formation of different macromolecular aggregates. Furthermore, the proper selection of the guest allows for the “turning on” or “turning off” of molecular threading and can be used to produce new kinds of threaded species. This dynamic behavior is a special feature of the Texas-sized molecular box, as is its ability to stabilize a range of polypseudorotaxanes, rotaxane-containing metal–organic frameworks (MORFs), and rotaxane-based supramolecular organic frameworks (RSOFs).</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/achre4/2012/achre4.2012.45.issue-8/ar300076b/production/images/medium/ar-2012-00076b_0015.gif'></P>

Educating for Conversion

Lewis R. Rambo 한국기독교교육정보학회 2006 Journal of Christian education information tech Vol.0 No.9

During the last two centuries, the processes of Christian education and conversion have been considered polarized. This paper argues that for Christianity to flourish in the 21st century Christian Education and conversion should not only intersect, but can be mutually supportive. First, this paper explores the tragic split between "liberals" and "conservatives." Second, this paper will examine the emergence of a new form of Roman Catholic theology that considers conversion to be foundational to the theological enterprise of the contemporary church. Third, I will propose a theological agenda that brings conversion studies and Christian education together to meet the needs of the church in the 21st century by engaging post-modernism and inter-disciplinary studies in theological and religious studies. Fourth, a radical form of discipleship will be proposed that can unify or transcend the traditional "liberal" and "conservative" agendas. Through both Christian education and radical conversion we are called to be transformed into the image of Christ.

Adventures in Education

Lewis R. Rambo 한국기독교교육정보학회 2011 Journal of Christian education information tech Vol.0 No.19

This paper seeks to discern themes and patterns in our search to make sense of the vicissitudes of current academic disciplines (especially religious education and pastoral psychology) through explorations of the resources of film, culture, and religion/spirituality. These resources provide cutting edge concepts, methods, and theories that can expand the horizons of religious education and pastoral psychology.

Through the Lens of Culture

Lewis R. Rambo 연세대학교 신과대학(연합신학대학원) 2006 신학논단 Vol.44 No.-

참살이: 회심의 적절한 목표의 하나인가?

루이스R.람보 ( Lewis R. Rambo ),반신환(역) 한국목회상담학회 2006 목회와 상담 Vol.8 No.-

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

Anion-directed assembly of a three-dimensional metal–organic rotaxane framework

Gong, Han-Yuan,Rambo, Brett M.,Cho, Won,Lynch, Vincent M.,Oh, Moonhyun,Sessler, Jonathan L. Royal Society of Chemistry 2011 Chemical communications Vol.47 No.21

<P>A three-dimensional extended, metal–organic rotaxane framework (MORF) that incorporates encircled “struts” has been synthesized through a one-pot self-assembly process involving a macrocyclic tetraimidazolium “molecular box”, naphthalene dicaboxylate dianion, and Zn(<SMALL>II</SMALL>) cations. The present system represents progress towards controlling the features of three-dimensional metal–organic frameworks.</P> <P>Graphic Abstract</P><P>A new one-pot self-assembly process is used to create a three-dimensional extended, metal–organic rotaxane framework (MORF) that incorporates encircled “struts”. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c1cc10272a'> </P>

In vivo Characterization of the Electrical Impedance between the Electrodes of the Electronic Foramen Locators

Humberto R. Gamba,Marcos V. H. Rambo,Gustavo B. Borba,Joaquim M. Maia,Carlos A. S. Ramos 대한의용생체공학회 2013 Biomedical Engineering Letters (BMEL) Vol.3 No.3

Purpose Electronic foramen locators are widely used to locate the apical foramen (AF), by measuring the electrical impedance between the electrodes (ZE). There is no in vivo study that completely characterizes ZE as a function of frequency and endodontic file tip position. The results of in vivo studies of the impedance ZE and a coefficient that can be used to locate the AF are presented. Methods An electronic device was specially built to study ZE. Ten root canals were used in the experiment. The spectral attenuation of ZE was in vivo measured with the endodontic file tip placed at -3.0, -2.5, -2.0, -1.5, -1.0, -0.5 and zero millimeters from the root canal AF. At each file position the spectrum attenuation was modeled. Based on the attenuation models an endodontic spectral attenuation coefficient (ESAC)was defined. Results The in vivo results demonstrate that the spectral attenuation of the electrical impedance ZE has an exponential decay in the frequency range of the study. It was verified that ESAC can be correlated to the distance between the endodontic file tip and the apical foramen. The ESAC accuracy was assessed and the results showed that it can locate the AF with accuracy better than 0.5mm. Conclusions The spectral attenuation of ZE has an exponential decay for all file tip distances from the AF. It supports the feasibility of ESAC to accurately locate the root canal AF. Moreover, using frequencies steps of one octave makes the implementation of ESAC in an embedded system easier.

Enhanced CO2 capture by cupuassu shell-derived activated carbon with high microporous volume

Cruz Orlando F.,Campello-Gómez Ignacio,Casco Mirian E.,Serafin Jarosław,Silvestre-Albero Joaquín,Martínez-Escandell Manuel,Hotza Dachamir,Rambo Carlos R. 한국탄소학회 2023 Carbon Letters Vol.33 No.3

Here, we report the preparation of microporous-activated carbons from a Brazilian natural lignocellulosic agricultural waste, cupuassu shell, by pyrolysis at 500 ºC and KOH activation under different experimental conditions and their subsequent application as adsorbent for CO2 capture. The effect of the KOH:precursor ratio (wt/wt%) and the activation temperature on the porous texture of activated carbons have been studied. The values of specific surface area ranged from 1132 to 2486 m2/g, and the overall micropore volume ranged from 0.73 to 1.02 cm3/g. Carbons activated with 2:1 ratio of KOH and activation temperature of 700 ºC presented a CO2 adsorption at 1 bar of 7.8 and 4.4 mmol/g at 0 °C and 25 ºC, respectively. The isosteric heat of adsorption, Qst , was calculated for all samples by applying the Clausius–Clapeyron approach to CO2 adsorption isotherms at both temperatures. The values of CO2 adsorption capacities are among the highest reported in the literature, especially for activated carbons produced from biomass.