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| Content Provider | World Health Organization (WHO)-Global Index Medicus |
|---|---|
| Author | Sánchez, Raul I. Cervantes, Ruy Tiburcio, Jorge |
| Description | Author Affiliation: Cervantes R ( Departmento de Química, Centro de Investigación y de Estudios Avanzados, Avenida IPN 2508, Zacatenco 07360, México D.â F., México.) |
| Abstract | Two different counter-ion-free host–guest complexes have been prepared and isolated. These compounds were formed from two equally and opposite doubly-charged species, the viologen guests $1 a^{2+}$ and $1 b^{2+}$ and the anti-disulfodibenzo[24]crown-8 $[DSDB24C8]^{2−}$ host, which gave rise to the 1:1 neutral complexes [1 a⋅DSDB24C8] and [1 b⋅DSDB24C8]. These species are held together by hydrogen bonding and π stacking, as well as strong electrostatic interactions. The investigation of these neutral ion-paired supramolecular systems in solution and in the solid state allowed us to establish their co-conformational preferences. Compound [1 a⋅DSDB24C8], with small methyl groups as substituents on the viologen unit, may adopt three different geometries, 1) an exo nonthreaded, 2) a partially threaded, and 3) a threaded arrangement, depending on the relative spatial orientation between the host and guest: The partially-threaded structure is preferred in solution and in the solid state. The presence of bulky tert-butylbenzyl groups in the viologen moiety in compound [1 b⋅DSDB24C8] restricts the possible geometrical arrangements to one: The exo nonthreaded arrangement. This structure was confirmed in the solid state by X-ray crystallography. The stability of the neutral complexes in solution was determined by UV/Vis spectrophotometry. The stoichiometry of the complexes was established by continuous variation experiments, and overall equilibrium constants and ΔG° values were determined on the basis of dilution experiments. The results observed are a consequence of only the intrinsic stability of the complexes as there are no additional contributions from counter ions. |
| ISSN | 09476539 |
| e-ISSN | 15213765 |
| Journal | Chemistry - A European Journal |
| Issue Number | 12 |
| Volume Number | 19 |
| Language | English |
| Publisher | Wiley-VCH;ChemPubSoc Europe |
| Publisher Date | 2013-03-18 |
| Publisher Place | Germany |
| Access Restriction | Open |
| Subject Keyword | Chemistry |
| Content Type | Text |
| Resource Type | Article |
| Subject | Organic Chemistry Catalysis |
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