TY - JOUR
T1 - A journey from calix[4]arene to calix[6] and calix[8]arene reveals more than a matter of size. Receptor concentration affects the stability and stoichiometric nature of the complexes
AU - Lavande, Nitin
AU - Acuña, Angel
AU - Basílio, Nuno
AU - Francisco, Vitor
AU - Malkhede, Dipalee D.
AU - Garcia-Rio, Luis
N1 - Sem pdf conforme despacho.
Ministerio de Economia y Competitividad of Spain (project CTQ2014-55208-P), Xunta de Galicia (GR 2007/085; IN607C 2016/03 and Centro singular de investigacion de Galicia accreditation 2016-2019, ED431G/09) and the European Regional Development Fund (ERDF) is gratefully acknowledged. This work was supported by the Associated Laboratory for Sustainable Chemistry-Clean Processes and Technologies-LAQV. The latter is financed by national funds from FCT/MEC (UID/QUI/50006/2013) and co-financed by the ERDF under the PT2020 Partnership Agreement (POCI-01-0145-FEDER-007265). N. B. gratefully acknowledges a postdoctoral grant from FCT/MEC (SFRH/BPD/84805/2012). V. F. acknowledges a postdoctoral grant, SFRH/BPD/102103/2014-Fundacao para a Ciencia e Tecnologia (FCT).
PY - 2017/1/1
Y1 - 2017/1/1
N2 - The formation of inclusion complexes between lucigenin (N,N′-dimethyl-9,9′-biacridinium dinitrate) and p-sulfonatocalix[n]arenes (SCn; n = 6, 8) was investigated by fluorescence and NMR spectroscopy. Both SC6 and SC8 were found to form 1:1 and 1:2 host-guest complexes with lucigenin showing up to 109 M-1 binding affinities. Strong quenching of the lucigenin fluorescence upon complexation was observed. Fluorescence regeneration after competitive binding with other potential guests present in solution was used as an indicator displacement assay to characterize the binding mechanism and affinity of alkaline metal ions (Li+, Na+, K+ and Cs+) with SC6 and SC8. The results demonstrate the formation of 1:1 and 1:2 calixarene:metal complexes with association constants on the order of 103 M-1 and heteroternary calixarene:lucigenin:metal complexes that predominate at metal cation concentrations above the millimolar range. Owing to the ubiquitous presence of metal cations in SCn solutions as counterions (typically Na+), the detailed description of the complexation of these species is crucial to understand and quantify the host-guest binding properties of these receptors. This work demonstrates that both the thermodynamic stability and the stoichiometric nature of the complexes is dependent on the metal ion concentration and, consequently, on the calixarene concentration.
AB - The formation of inclusion complexes between lucigenin (N,N′-dimethyl-9,9′-biacridinium dinitrate) and p-sulfonatocalix[n]arenes (SCn; n = 6, 8) was investigated by fluorescence and NMR spectroscopy. Both SC6 and SC8 were found to form 1:1 and 1:2 host-guest complexes with lucigenin showing up to 109 M-1 binding affinities. Strong quenching of the lucigenin fluorescence upon complexation was observed. Fluorescence regeneration after competitive binding with other potential guests present in solution was used as an indicator displacement assay to characterize the binding mechanism and affinity of alkaline metal ions (Li+, Na+, K+ and Cs+) with SC6 and SC8. The results demonstrate the formation of 1:1 and 1:2 calixarene:metal complexes with association constants on the order of 103 M-1 and heteroternary calixarene:lucigenin:metal complexes that predominate at metal cation concentrations above the millimolar range. Owing to the ubiquitous presence of metal cations in SCn solutions as counterions (typically Na+), the detailed description of the complexation of these species is crucial to understand and quantify the host-guest binding properties of these receptors. This work demonstrates that both the thermodynamic stability and the stoichiometric nature of the complexes is dependent on the metal ion concentration and, consequently, on the calixarene concentration.
KW - HOST-GUEST COMPLEXATION
KW - P-SULFONATOCALIXARENES
KW - AQUEOUS-SOLUTION
KW - HOST/GUEST COMPLEXES
UR - http://www.scopus.com/inward/record.url?scp=85024381568&partnerID=8YFLogxK
U2 - 10.1039/c7cp01889d
DO - 10.1039/c7cp01889d
M3 - Article
C2 - 28530732
AN - SCOPUS:85024381568
SN - 1463-9076
VL - 19
SP - 13640
EP - 13649
JO - Physical Chemistry Chemical Physics
JF - Physical Chemistry Chemical Physics
IS - 21
ER -