4,2’:6’,4”- and 3,2’:6’,3”-Terpyridines: The Conflict between Well-Defined Vectorial Properties and Serendipity in the Assembly of 1D-, 2D- and 3D-Architectures

Abstract

A comparative investigation of the coordination assemblies formed between Co(NCS)2 and two monotopic 4,2’:6’,4’’-terpyridine (4,2’:6’,4”-tpy) ligands or two related ditopic ligands is reported. Crystals were grown by layering MeOH solutions of Co(NCS)2 over a CHCl3 or 1,2-C6H4Cl2 solution of the respective ligand at room temperature. With 4’-(2-methylpyrimidin-5-yl)-4,2’:6’,4”-terpyridine (6), the 1D-coordination polymer {[Co2(NCS)4(MeOH)4(6)2]∙2MeOH∙8H2O}n assembles with 6 coordinating only through the outer N-donors of the 4,2’:6’,4”-tpy unit; coordination by the MeOH solvent blocks two cobalt coordination sites preventing propagation in a higher-dimensional network. A combination of Co(NCS)2 and 1-(4,2‘:6’,4”-terpyridin-4’-yl)ferrocene (7) leads to {[Co(NCS)2(7)2]∙4CHCl3}n which contains a (4,4) net; the 2D-sheets associate through π-stacking interactions between ferrocenyl and pyridyl units. A 3D-framework is achieved through use of the ditopic ligand 1,4-bis(npropoxy)-2,5-bis(4,2’:6’,4”-terpyridin-4’-yl)benzene (8) which acts as a 4-connecting node in {[Co(NCS)2(8)2]∙2C6H4Cl2}n; the combination of metal and ligand planar 4-connecting nodes results in a {65.8} cds net. For a comparison with the coordinating abilities of the previously reported 1,4-bis(noctoxy)-2,5-bis(4,2’:6’,4”-terpyridin-4’-yl)benzene (3), a more flexible analogue 9 was prepared. {[Co(NCS)2(9)]∙2CHCl3}n contains a (4,4) net defined by both metal and ligand planar 4-connecting nodes. The noctoxy tails of 9 protrude from each side of the (4,4) net and thread through adjacent sheets; the arene-attached noctoxy chains associate through a combination of van der Waals and C–H...π interactions.

Tetratopic bis(4,2′:6′,4′′-terpyridine) and bis(3,2′:6′,3′′-terpyridine) Ligands as 4-Connecting Nodes in 2D-Coordination Networks and 3D-Frameworks

“…Once again, it appears that the length of the n alkoxy tail is a significant factor is controlling the coordination network assembly. example [50]. As shown in Fig.…”

Four Novel Zn (II) Coordination Polymers Based on 4′-Ferrocenyl-3,2′:6′,3′′-Terpyridine: Engineering a Switch from 1D Helical Polymer Chain to 2D Network by Coordination Anion Modulation

“…Terpyridines, which are oligopyridines, represent a very popular and versatile building block of ligands for the constructing functional complexes [ 1 ]. Terpyridines possess 48 isomers, of which the 2,2′:6′,2′′-terpyridine, 3,2′:6′,3′′-terpyridine and 4,2′:6′,4′′-terpyridine ( Figure 1 ) are well known, above all because of their ease of synthesis and functionalization in the 4′-position [ 1 , 2 , 3 , 4 , 5 , 6 ].…”

“…The two type terpyridine ligands can coordinate with metal ions in the outer pyridine rings, while the central pyridine rings are usually not involved in coordination [ 2 , 11 ]. The inter-ring C–C bond rotations have no effect on the ligand conformer ( Figure 1 c), and therefore 4,2′:6′,4′′-terpyridine, which acts as an excellent V-shaped building block, has received increasing attention [ 2 , 4 , 5 , 12 ]. There are over 200 types of complexes, which have been reported with this type of terpyridine in coordination polymers and networks etc.…”

“…There are over 200 types of complexes, which have been reported with this type of terpyridine in coordination polymers and networks etc. [ 2 , 4 , 5 , 12 ].…”

“…To date, the complexes containing this type of ligand have rarely been explored, with only more than twenty complexes reported in total [ 2 , 13 ]. In particular, more efforts should be made to search for functionalized 3,2′:6′,3′′-terpyridine ligands in the field of coordination chemistry and materials [ 4 , 13 , 14 , 15 , 16 , 17 , 18 , 19 ].…”