To Loop or Not to Loop: Influence of Hinge Flexibility on Self‐Assembly Outcomes for Acridine‐Based Triazolylpyridine Chelates with Zinc(II), Iron(II), and Copper(II).

Miron, Caitlin E.; Fleischel, Olivier; Petitjean, Anne

Coordination‐driven self‐assembly has been established as an effective strategy for the efficient construction of intricate architectures in both natural and artificial systems, for applications ranging from gene regulation to metal–organic frameworks. Central to these systems is the need for carefully designed organic ligands, generally with rigid components, that can undergo self‐assembly with metal ions in a predictable manner. Herein, we report the synthesis and study of three novel organic ligands that feature 3,6‐disubstituted acridine as a rigid spacer connected to two 2‐(1,2,3‐triazol‐4‐yl)pyridine "click" chelates through hinges of the same length but differing flexibility. The flexibility of these "three‐atom" hinges was modulated by i) moving from secondary to tertiary amide functional groups and ii) replacing an sp2 amide carbon with an sp3 methylene carbon. In an effort to understand the role of hinge flexibility in directing self‐assembly into mononuclear loops or dinuclear cylinders, the impact of these changes on self‐assembly outcomes with zinc(II), iron(II), and copper(II) ions is described. Staying in the loop: A series of organic ligands, each bearing an acridine unit connected to two terminal 1,2,3‐triazolepyridine "click" chelates by means of three‐atom hinges, undergoes self‐assembly in solution with ZnII, FeII, and CuII. The loop and cylinder architectures produced illustrate the profound effect that can be exerted by tuning hinge flexibility through changes to the sp2/sp3 character of a single carbon atom (see figure).

MOLECULAR self-assembly; PYRIDINE; ZINC compounds; LIGANDS (Chemistry); ACRIDINE; METAL-organic frameworks

Chemistry - A European Journal, 2018, Vol 24, Issue 65, p17318

0947-6539

Academic Journal

10.1002/chem.201803732