Linked Life Data

14519016

Source:http://linkedlifedata.com/resource/pubmed/id/14519016

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
40
pubmed:dateCreated
2003-10-1
pubmed:abstractText
A supramolecular dimeric rhomboid and its trimeric counterpart, a hexagon, are generated by design via the directional bonding methodology of self-assembly. The different-sized supramolecular macrocycles formed by Pt-coordination undergo a concentration- and temperature-dependent dynamic equilibrium. The two structures are characterized by multinuclear NMR and ESI-MS. Extensive study of the dynamic equilibrium of the two species in solution is performed to obtain its thermodynamic properties. By varying the ionic strength, mu, of the solutions, the true thermodynamic equilibrium constant, K, is determined at each experimental temperature (K(253) = 36 +/- 7, K(273) = 18 +/- 6, K(293) = 10 +/- 3, K(313) = 9 +/- 2, K(333) = 5 +/- 2, and K(353) = 3.0 +/- 0.2). By applying these values of true K at the respective temperatures to the van't Hoff equation extended with the entropy term, the standard enthalpy and entropy changes are determined for the equilibrium: with Delta H degrees = -18 +/- 1 kJ mol(-1) and Delta S degrees = -43 +/- 4 J mol(-1) K(-1), respectively, for the forward reaction (rhomboid to hexagon) of the equilibrium. The rhomboid is selectively crystallized, and its crystal structure is determined by X-ray diffraction. The structure reveals a significant amount of porosity as well as distortion of the rhomboid from planarity, leading to channels that can be observed from two viewing positions of the packing.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Oct
pubmed:issn
0002-7863
pubmed:author
pubmed:issnType
Print
pubmed:day
8
pubmed:volume
125
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
12309-17
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
2003
pubmed:articleTitle
Dynamic equilibrium of a supramolecular dimeric rhomboid and trimeric hexagon and determination of its thermodynamic constants.
pubmed:affiliation
Department of Chemistry, University of Utah, 315 South 1400 East, Salt Lake City, Utah 84112, USA.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, U.S. Gov't, Non-P.H.S.