Cyclohexane-Based Conformationally Controlled Crowns and Podands

Abstract

Cyclohexane-based conformationally controlled ionophores, the emerging new class of molecular switches, provide a new and promising approach to allosteric systems with negative cooperativity.

Fliposomes: stimuli-triggered conformational flip of novel amphiphiles causes an instant cargo release from liposomes

“…Previously, we used the trans-2-aminocyclohexanol moiety to construct the conformationally controlled crown ethers and podands (29,30,47,48). The driving force of this dramatic acid-triggered transition is a strong, protonation-generated intramolecular hydrogen bond of HO···H-N + type and an electrostatic/ dipole-dipole attraction stabilizing a conformer with the gauche form of O-C-C-N fragment (1BH + in Figure 1).…”

“…Mechanical or conformational molecular switches are molecular systems that reversibly change the relative orientation of their parts under external influence. They play a central role in the design of molecular machinery, controllable compounds, and intelligent materials for possible use in many applications, including drug release, new sensor techniques, or information storage and transmission (25)(26)(27)(28)(29)(30)(31). Cyclohexane-based molecular devices have been designed as a new type of such switches (29)(30)(31).…”

Trans‐2‐Aminocyclohexanol derivatives as pH‐triggered conformational switches

“…Mechanical or conformational molecular switches are molecular systems that reversibly change the relative orientation of their parts under external stimulus. They play a central role in a design of controllable compounds, molecular machinery, and intelligent materials with a variety of possible applications including drug release, new sensor techniques, or information storage and transmission . The cyclohexane‐based molecular systems have been designed as an efficient type of such switches .…”

“…They play a central role in a design of controllable compounds, molecular machinery, and intelligent materials with a variety of possible applications including drug release, new sensor techniques, or information storage and transmission . The cyclohexane‐based molecular systems have been designed as an efficient type of such switches . In particular, we used the trans ‐2‐aminocyclohexanol moiety 1 (Scheme ) to construct the conformationally controlled crown ethers and podands and the pH sensitive “flipids” for “fliposomes.” An interaction of acid with these compounds leads to protonation of the amino group and generates a strong intramolecular hydrogen bond of O⋅⋅⋅H‐N + type (in 1B ·H + on Scheme ), which stabilizes the originally unstable conformer B , thus moving the ester groups COOR at the other end of the molecule away from each other (peacock effect).…”

“…The cyclohexane‐based molecular systems have been designed as an efficient type of such switches . In particular, we used the trans ‐2‐aminocyclohexanol moiety 1 (Scheme ) to construct the conformationally controlled crown ethers and podands and the pH sensitive “flipids” for “fliposomes.” An interaction of acid with these compounds leads to protonation of the amino group and generates a strong intramolecular hydrogen bond of O⋅⋅⋅H‐N + type (in 1B ·H + on Scheme ), which stabilizes the originally unstable conformer B , thus moving the ester groups COOR at the other end of the molecule away from each other (peacock effect). This move changes dramatically their ability to interact with another molecule or ion, or to pack into lipid bilayers (depending on the nature of R).…”