Synthesis and Metal‐Binding Properties of Polybipyridine Ligands Derived from Acyclic and Macrocyclic Polyamines

Abstract

Synthetic procedures have been developed for the preparation ofligands bearing two to six pendent, unsubstituted or substituted 2,2'-bipyridine groups attached to acyclic (tripode, tetrapode) and macrocyclic (triazanonadecane, cyclam, hexacyclen, bis(bipyrido)hexaazamacrocycle) polyamines. Ligands 1-5 have been obtained in high yield by condensation of 6-(bromomethyl)-2,2'-bipyridine (9b) with the corresponding amines in the presence of NaOH, H20, and MeOH. Ligands &8 have been prepared in good yield by condensation of 9b or the di-or tetrasubstituted mono(bromomethy1)bipyridine 10b or l l b , respectively, with the corresponding amines in the presence of Na2C03 and MeCN. Ligand 1 forms hemi-cage complexes with Ru", Fe", Cr", and Cr"' cations and trinuclear complexes with [R~Cl,(bpy)~] and [ReCI(CO)5]. Tetrapode 2 and hexapode 4 gave tetranuclear and dinuclear complexes, respectively, by reaction with Fe" salts. These complexes possess a variety of interesting physical and chemical properties.Introduction. -The coordination chemistry of 2,2'-bipyridine (bpy) ligands has received considerable interest in the past two decades [l]. The properties of the long-lived, luminescent, metal-to-ligand-charge-transfer state, characteristic of polypyridine transition-metal complexes, enable these compounds to sensitize photoinduced electron-transfer and energy-transfer processes [2-41. These attractive features prompted the introduction of the bpy subunit into macrocyclic [5-91 and mdcrobicyclic structures [6] [10-14], thus, yielding ligands capable of forming photoactive metal-cage complexes. In particular, inclusion complexes of lanthanides [ 15-1 71 and ruthenium(I1) [ 181 [ 191 have been shown to combine the features of polycyclic structures with the properties associated with bpy groups. Less rigid (e. g . acyclic or branched) polydentade complexing agents allow binding properties and structural flexibility to be combined and are well adapted for the synthesis of hemi-caged metal complexes. Moreover, these kinds of ligands are suitable for the preparation of polymetallic complexes which are of interest for their potential multiredox and catalytic properties. One could also envisage that caged or hemi-caged metal ions would prevent ligand photodissociation, hence increasing both excited-state life-times and luminescence quantum yields [18] [20].Pyridine tripode-type ligands, such as tris[(pyrid-2-yl)methyl]amine, were first synthesized twenty years ago [21], and the stability constants of their numerous first-row-transition-metal complexes have been determined [22] [25], bis[2-(pyrid-2-yl)ethyl]amine connected by alkyl chains of varying lengths [26], and tetrakis(picoly1)diamine joined together by a C , or C, chain [27]. Polyazamacrocycles functionalized

Influence of Solvent on Ligand‐Substitution Reactions of PtII Complexes as Function of the ‐Acceptor Properties of the Spectator Chelate

“…[Pt(diethylenetriamine)Cl]CF 3 SO 3 (aaa): [18] : The ligand 2,6-bis(aminomethyl)pyridine was prepared according to a method used to synthesize 6-(aminomethyl)-2,2Ј-bipyridine [19] by using 2,6-bis(bromomethyl)pyridine [20] as starting material. [7] The corresponding platinum complex was prepared as described in the literature [7] and was obtained in the same quality (0.260 g, 38 % …”

A Water‐Soluble Calix[4]arene‐Based Podand Incorporating 4,4′‐Dicarboxy‐2,2′‐bipyridine Chelating Units − Synthesis and Complexation Properties towards Copper Ions

“…[35] A similar but longer process involving the consecutive formation of the trifluoroacetate, the alcohol, the mesylate, and then the bromide was also described for the tert-butyl ester analogue of 3, [37] as well as another procedure involving a radical bromination. [38] Following the procedure previously reported by Beer et al [39] for the unsubstituted bipyridine, the monobromide 3, calix [4]arenetetrol, and K 2 CO 3 were heated to reflux in MeCN to give the podand 4 in a yield of 83% after chromatography (SiO 2 , CH 2 Cl 2 ). The four ester functions of 4 were saponified in an aqueous alcoholic NaOH solution at reflux.…”

Synthesis, Characterization and DFT Studies of 4-(2,4-Difluorobiphenyl-4-Yl)-6-Phenylpyrimidin-2-Amine

“…In addition, they possess a wide range of biological effectiveness such as antimicrobial [4], calcium channel blockers [5], antitubercular, anticancer [6], antibacterial [7] and anti-inflammatory [8] activities. Especially 2-amino substituted pyrimidine has frequently been studied during the recent decades as they act as synthetic precursors in a variety of organic conversions and in coordination chemistry [9]. Moreover, many fluorinated scaffolds are known to exhibit a broad range of biological activities in medicinal and agricultural scientific fields [10].…”