4,2′:6′,4′′-Terpyridines: diverging and diverse building blocks in coordination polymers and metallomacrocycles

Abstract

4,2':6',4''-Terpyridine (4,2':6',4''-tpy) is one of the less well documented isomers of the well-established bis-chelating 2,2':6',2''-terpyridine. The N-donors of the outer rings in 4,2':6',4''-tpy subtend an angle of 120°, leading to a description of 4,2':6',4''-tpy as a divergent ligand. Because it typically binds metal ions through the outer N-donors only, 4,2':6',4''-tpy is an ideal linker for combination with metal nodes (often geometrically flexible d(10) ions) in coordination polymers and metallomacrocyclic complexes. The facile functionalization of terpyridines in the 4'-position allows access to a suite of 4'-X-4,2':6',4''-tpy ligands in which the 4'-substituent, X, can be selected to assist in directing the metal-ligand assembly process. This overview of recent advances in the chemistry of 4,2':6',4''-tpy and its 4'-substituted derivatives looks at relationships within a series of chiral polymers, competition between the formation of metallocyclic complexes versus polymers, and the use of extended aryl systems to encourage the formation of coordination polymers in which π-stacking of arene domains dominates in the assembly process. Use of metal(ii) acetates is key to the formation of paddle-wheel and larger cluster nodes that direct the assembly of both predetermined and unexpected architectures.

Coordination Behaviour of 1-(4,2′:6′,4′′-terpyridin-4′-yl)ferrocene and 1-(3,2′:6′,3′′-terpyridin-4′-yl)ferrocene: Predictable and Unpredictable Assembly Algorithms

“…[22,31] During the course of our investigations of the coordination chemistry of the ferrocenyl-functionalized 4,2':6',4''-and 3,2':6',3''-terpyridines shown in Scheme 2, Tian and coworkers reported that 2 reacts with ZnCl2 and ZnBr2 to give the discrete metallohexacycles 9…”

“…[21] Ligand 2 reacts with ZnCl2 and ZnBr2 to give discrete metallohexacycles similar to those obtained with other 4'-substituted 4,2':6',4'-tpy ligands. [22] 1D-coordination polymers result when 2 is treated with ZnI2, Zn(NCS)2 and Zn(OAc)2. We now report the synthesis and coordination behaviour of 1-(3,2':6',3''-terpyridin-4'-yl)ferrocene (3, Scheme 2) with ZnCl2 and ZnBr2, and also demonstrate competitive assembly pathways to different structure types using ligands 2 and 3.…”

Metallo-Terpyridine-Modified Cellulose Nanofiber Membranes for Papermaking Wastewater Purification

“…Different polymeric architectures (dendrimers, hyperbranched, and linear) containing or based on terpyridine have been published [1][2][3]. Whereas there are a large number of publications concerned with polymers bearing different terpyridine ligands, the preparation of the first, terpyridine-modified, cellulose polymer was reported during 2012 in Professor Newkome' laboratories at the University of Akron through his collaboration with our group at the National Research Centre in Egypt.…”

4′-(Pyrimidin-5-yl)- and 4′-(2-methylpyrimidin-5-yl)-4,2′:6′,4″-terpyridines: Selective coordination to zinc(II) through the 4,2′:6′,4″-terpyridine domain

“…The use of 4,2':6',4''-terpyridine (4,2':6',4''-tpy) ligands as metal-binding domains for the assembly of coordination polymers is highly attractive and topical [1]. Of the three nitrogen donors in 4,2':6',4''-tpy, only the outer two typically bind metal ions leading to a divergent, V-shaped building block with well-defined directionality.…”