<?xml version="1.0" encoding="UTF-8"?><xml><records><record><source-app name="Biblio" version="6.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Gamez, F.</style></author><author><style face="normal" font="default" size="100%">Hurtado, P.</style></author><author><style face="normal" font="default" size="100%">Hamad, S.</style></author><author><style face="normal" font="default" size="100%">Martinez-Haya, B.</style></author><author><style face="normal" font="default" size="100%">Berden, G.</style></author><author><style face="normal" font="default" size="100%">Oomens, J.</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Tweezer-like Complexes of Crown Ethers with Divalent Metals: Probing Cation-Size-Dependent Conformations by Vibrational Spectroscopy in the Gas Phase</style></title><secondary-title><style face="normal" font="default" size="100%">Chempluschem</style></secondary-title><alt-title><style face="normal" font="default" size="100%">ChemPlusChem</style></alt-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">12-CROWN-4</style></keyword><keyword><style  face="normal" font="default" size="100%">18-CROWN-6</style></keyword><keyword><style  face="normal" font="default" size="100%">ALKALINE-EARTH CATIONS</style></keyword><keyword><style  face="normal" font="default" size="100%">BINDING</style></keyword><keyword><style  face="normal" font="default" size="100%">BIS(CROWN ETHER)</style></keyword><keyword><style  face="normal" font="default" size="100%">crown ethers</style></keyword><keyword><style  face="normal" font="default" size="100%">density functional calculations</style></keyword><keyword><style  face="normal" font="default" size="100%">divalent metals</style></keyword><keyword><style  face="normal" font="default" size="100%">infrared</style></keyword><keyword><style  face="normal" font="default" size="100%">INFRARED-SPECTROSCOPY</style></keyword><keyword><style  face="normal" font="default" size="100%">IONS</style></keyword><keyword><style  face="normal" font="default" size="100%">MOLECULAR RECOGNITION</style></keyword><keyword><style  face="normal" font="default" size="100%">MOLECULAR-TWEEZERS</style></keyword><keyword><style  face="normal" font="default" size="100%">MULTIDENTATE LIGANDS</style></keyword><keyword><style  face="normal" font="default" size="100%">RECOGNITION</style></keyword><keyword><style  face="normal" font="default" size="100%">SPECTROSCOPY</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2012</style></year><pub-dates><date><style  face="normal" font="default" size="100%">Feb</style></date></pub-dates></dates><urls><web-urls><url><style face="normal" font="default" size="100%">&lt;Go to ISI&gt;://WOS:000301839800006 </style></url></web-urls></urls><number><style face="normal" font="default" size="100%">2</style></number><volume><style face="normal" font="default" size="100%">77</style></volume><pages><style face="normal" font="default" size="100%">118-123</style></pages><isbn><style face="normal" font="default" size="100%">2192-6506</style></isbn><language><style face="normal" font="default" size="100%">English</style></language><abstract><style face="normal" font="default" size="100%">Crown ethers constitute central building blocks for the synthesis of molecular tweezers capable of trapping cationic species. In this study, isolated ternary complexes comprising two [18]crown-6 (18c6) ether molecules and one divalent cation of varying size (Cu2+, Ca2+, Ba2+) are investigated by means of laser vibrational action spectroscopy and computations. In the ternary (18c6)(2)-Cu2+ complex, one of the crown units folds tightly around the cation, while the second crown ether unit binds peripherally. Such asymmetrical binding manifests itself as a bimodal splitting of the vibrational bands measured for the complex. The size of the cation in the Ca2+ and Ba2+ complexes leads to a progressively more symmetrical coordination of the two crown ether molecules with the metal. In particular, in the spectrum of the (18c6)(2)-Ba2+ complex, the two components of the vibrational bands are merged into single-maximum envelopes. This is consistent with a C-2 arrangement predicted by the computation, in which the cation coordinates with the two crown ether units in a fully symmetrical way.</style></abstract><work-type><style face="normal" font="default" size="100%">Article</style></work-type><accession-num><style face="normal" font="default" size="100%">WOS:000301839800006</style></accession-num><notes><style face="normal" font="default" size="100%">ISI Document Delivery No.: 912YZTimes Cited: 0Cited Reference Count: 38</style></notes><custom1><style face="normal" font="default" size="100%">GUTHz</style></custom1><custom2><style face="normal" font="default" size="100%">FELIX</style></custom2><auth-address><style face="normal" font="default" size="100%">[Gamez, Francisco; Hurtado, Paola; Hamad, Said; Martinez-Haya, Bruno] Univ Pablo Olavide, Dept Phys Chem &amp; Nat Syst, Seville 41013, Spain. [Berden, Giel; Oomens, Jos] FOM Inst Plasma Phys Rijnhuizen, NL-3439 MN Nieuwegein, Netherlands. [Oomens, Jos] Univ Amsterdam, NL-1098 XH Amsterdam, Netherlands.Martinez-Haya, B (reprint author), Univ Pablo Olavide, Dept Phys Chem &amp; Nat Syst, Seville 41013, Spainbmarhay@upo.es</style></auth-address></record></records></xml>