Recognition-Directed Supramolecular Assemblies of Metal Complexes of Terpyridine Derived Ligands with Self-Complementary Hydrogen Bonding Sites

Abstract

The synthesis and X-ray structures of three metal complexes with terpyridine-derived ligands that contain amino-pyrimidine and amino-pyrazine moieties are presented. They have been designed in view of directing their self-assembly into specific supramolecular arrays through molecular recognition interactions. The solid-state structures indeed reveal extensive hydrogen-bonded networks. The Co complex 4a with PF6- counterions builds a two-dimensional infinite interwoven grid through strong double hydrogen bonds (d(N-H-N) =2.918-3.018 A) between the amino groups and the N atoms of the rings, with all H-bonding sites saturated. Changing the anions to BF4- in 4b leads to a similar infinite but partially broken grid with a quarter of the H-bonding sites unsaturated (d(N-H-N)=2.984-3.206 A). In the case of the Zn complex 12 with triflate anions, half of the hydrogen bonds are formed. Only one of the two orthogonal ligands has hydrogen bonds (d(N-H-N) = 3.082, 3.096 A) to the neighbouring complexes and thus builds linear, supramolecular, polymeric chains. These structural differences are mainly attributed to crystal-packing effects caused by the different anions. The data presented here may also be regarded as a prototype for the generation of organised arrays through sequential self-assembly processes.

Controlling supramolecular polymerization through multicomponent self‐assembly

“…231 The use of metal coordination chemistry to build metallosupramolecular polymers has been extensively investigated, aided by the large variety of ligands or metal ions, which effect the strength, dynamics and reversibility of the supramolecular linkage. [232][233][234][235][236][237][238][239] A number of excellent reviews in this specific area highlight the influence of the ligand metal interaction, solvent polarity and coordination capability on the degree of polymerization and the dynamic properties. [240][241][242][243][244] It is interesting to point out that in noncoordinating solvents coordination polymers can be kinetically inert and behave like conventional covalent polymers, whereas the presences of traces of coordinating solvent or free ligand increases the exchange rate for the metal coordination bond and impart supramolecular behavior such as stimuli-responsive behavior toward external stimuli.…”

Iron(ii) and cobalt(ii) complexes of tris-azinyl analogues of 2,2′:6′,2′′-terpyridine

“…The incorporation of additional hydrogen-bond acceptor sites into the terpy skeleton can be a useful approach to constructing hydrogen-bonded host:guest 30 complexes. 10,13 Moreover, nitrogen rich tris-azines are better -acceptors than terpy itself, which can lead to their complexes showing enhanced fluorescence.…”

Two-Level Self-Organisation of Arrays of [2×2] Grid-Type Tetranuclear Metal Complexes by Hydrogen Bonding

“…The suitability of aminopyrazine and aminopyrimidine as designed hydrogen-bonding motifs, as used here, has been shown before in mononuclear complexes with terpyridine-derived ligands. [8] Figure 1. Schematic representation of the generation of the two-level sequential self-assembly of an ordered alternating ''grid-of-grids'' pattern of two [2ϫ2] M 4 II grid-type species (such as 4Ϫ7) incorporating different metal ions; the long range organisation is provided by secondary interactions, such as complementary hydrogen bonding (as represented), but also electrostatic interaction or metal ion coordination, between the termini of the ligands from grid to grid Scheme 1.…”

“…, 1 H, H 4Ј ),8.30 (dd, J ϭ 1.5 and 7.9 Hz, 1 H, H 3Ј or 5Ј ),8.60 (d, J ϭ 1.2 Hz, 1 H, H 2 or 5 ),9.04 (d, J ϭ 1.2 Hz, 1 H, H 2 or 5 ).4,6-Bis[6-{6-[bis(tert-butoxycarbonyl)amino]pyrimidin-4-yl}pyrid-2-yl]-2-phenylpyrimidine (19): 6-[Bis(tert-butoxycarbonyl)amino]--dichloro-2-phenylpyrimidine (34 mg, 0.15 mmol), and Pd(PPh 3 ) 4 (17 mg, 0.015 mmol) were combined in toluene (2 mL), flushed with Ar, and heated under reflux for 22 h. The solvent was evaporated and the residue purified by column chromatography on silica with hexane/EtOAc (4:1, changing to 1:1, v/v) to give 19 as a pale yellow powder. Yield 72 mg (50%).…”