(1) Flipped-out and switched-on ionophores. (2) Conformationally controlled intramolecular charge transfer complexes. (3) Intramolecular charge transfer ionophores

摘要

Our interest in novel organic structures that possess physical properties as a sole function of their conformation and/or stereochemistry led to the development of new classes of materials, termed "Flipped-out" and "Switched-on" ionophores. These compounds can be prepared in good yields from commercially available starting materials. The Flipped-out ionophores possess conformational biasing groups that facilitate determination of the association constant of the incorporated ionophore module by variable temperature NMR spectroscopy. The Switched-on ionophores contain chemical groups that drastically restrict the ability of the attached ionophore to complex metal cations. Upon simple chemical manipulation, the restricting functional group can be removed, or altered, to allow the ionophore to complex metal ions. This is viewed as a potential model for synthetic antibiotics.;The second portion of this work deals with controlling the ability of two groups, one electron rich and one electron poor, contained within the same structure to form intramolecular charge transfer complexes. The two CT components are linked via a cyclohexane ring that is conformationally controllable. The conformation of the cyclohexane ring can be changed by chemical means which, in turn, reveals the possibility for a molecular light switch. The intensity of the intramolecular charge transfer absorption band can be controlled by this chemical manipulation. A possible application of this relationship is the colorometric determination of reaction rates.;The final segment of this report deals with the development of chromogenic ionophores that exhibit affinities for both alkali metal and alkaline earth cations. These ionophores contain an isolated, conformationally-linked intramolecular charge transfer complex that is broken apart upon complexation of the included ionophore with a cation, giving rise to a molecular logic "and/or" device. This novel method of inducing color change upon complexation is different than most of the previously reported literature studies, in that the electronic effect of complexation by the ionophore is not the primary cause of the induced color change. These materials shows potential use as analytical reagents for the colorometric determination of metal cations in solution.