A Rare Chiral Self-Catenated Network Formed by Two Cationic and One Anionic Frameworks

Mononuclear Rare-Earth Metalloligands Exploiting a Divergent Ligand

Rare-earth tris-diketonato [RE(dike)3pyterpy] metalloligands can be prepared reacting at room temperature [RE(dike)3dme] (dme = 1,2-dimethoxyethane; dike = tta with Htta = 2-thenoyltrifluoroacetone and RE = La, 1; Y, 2; Eu, 3; Dy, 4; or dike = hfac with Hhfac hexafluoroacetylacetone, and RE = Eu, 5; Tb, 6; Yb 7) with 4'-(4‴-pyridil)-2,2':6',2″-terpyridine (pyterpy). The molecular structures of 1, 5, 6, and 7 have been studied through single-crystal X-ray diffraction showing mononuclear neutral complexes with the rare-earth ion in coordination number nine and with a muffin-like coordination geometry. [RE(tta)3pyterpy] promptly reacts with [M(tta)2dme] with formation of [Mpyterpy2][RE(tta)4]2 (M = Zn, RE = Y, 8; M = Co, RE = Dy, 9). Consistently, [Zn(hfac)2dme] reacts at room temperature with 2 equiv of pyterpy yielding [Znpyterpy2][hfac]2 10 that easily can be transformed by reaction with 2 equiv of [Eu(hfac)3] in [Znpyterpy2][Eu(hfac)4]2 11 that has been structurally characterized. Finally, 1, 2, 3, 5, and 7 metalloligands react at room temperature in few minutes with [PtCl(μ-Cl)PPh3]2 yielding the heterometallic molecular complexes [RE(dike)3pyterpyPtCl2PPh3] (dike = tta, RE = La, 12; Y, 13; Eu; 14; dike = hfac, RE = Eu, 15; Yb, 16).

Tailored Inorganic-Organic Architectures via Metalloligands

This article discusses the design principles and strategies and the structural outcome of various supramolecular architectures constructed by utilizing well-defined coordination complexes as the metalloligands. We have included selected examples of metalloligands, offering either pyridyl or arylcarboxylic acid groups as the appended functional groups, for illustrating the construction of their supramolecular architectures. Both geometrical position and the number of the appended functional groups emerging from a metalloligand were found to critically regulate the structural aspects and dimensionality of the resultant material. The article concludes by delineating the structure-directing lessions as well as the potential applications of the metalloligand-based supramolecular architectures for the generation of next-level materials.

Terpyridine-Based 3D Metal-Organic-Frameworks: A Structure-Property Correlation

Design, synthesis, and applications of metal-organic frameworks (MOFs) are among the most salient fields of research in modern inorganic and materials chemistry. As the structure and physical properties of MOFs are mostly dependent on the organic linkers or ligands, the choice of ligand system is of utmost importance in the design of MOFs. One such crucial organic linker/ligand is terpyridine (tpy), which can adopt various coordination modes to generate an enormous number of metal-organic frameworks. These frameworks generally carry physicochemical characteristics induced by the π-electron-rich (basically N-electron-rich moiety) terpyridines. In this minireview, the construction of 3D MOFs associated with symmetrical terpyridines is discussed. These ligands can be easily derivatized at the lateral phenyl (4'-phenyl) position and incorporate additional organic functionalities. These functionalities lead to some different binding modes and form higher dimensional (3D) frameworks. Therefore, these 3D MOFs can carry multiple features along with the characteristics of terpyridines. Some properties of these MOFs, like photophysical, chemical selectivity, photocatalytic degradation, proton conductivity, and magnetism, etc. have also been discussed and correlated with their frameworks.

Effect of pyridyl donors from organic ligands versus metalloligands on material design

This review illustrates designs and structures of various coordination frameworks constructed using assorted organic ligands and metalloligands offering pyridyl donors to evaluate the impact of flexibility versus rigidity on material design.

Enabling photocatalytic activity of [Ru(2,2′:6′,2′′-terpyridine)2]2+ integrated into a metal–organic framework

A multicomponent metal–organic framework is constructed to incorporate the bis-terpyridyl ruthenium motif, which was considered poorly photoactive, through a stepwise reticular synthesis to arouse its photosensitiveness for producing singlet oxygen.

Terpyridine-metal complexes: effects of different substituents on their physico-chemical properties and density functional theory studies

A series of different substituted terpyridine (tpy)-based ligands have been synthesized by Kröhnke method. Their binding behaviour was evaluated by complexing them with Co(II), Fe(II) and Zn(II) ions, which resulted in interesting coordination compounds with formulae, [Zn(tpy)₂]PF₆, [Co(tpy)₂](PF₆)₂, [Fe(tpy)₂](PF₆)₂ and interesting spectroscopic properties. Their absorption and emission behaviours in dilute solutions were investigated in order to explain structure-property associations and demonstrate the impact of different aryl substituents on the terpyridine scaffold as well as the role of the metal on the complexes. Photo-luminescence analysis of the complexes in acetonitrile solution revealed a transition from hypsochromic to bathochromic shift. All the compounds displayed remarkable photo-luminescent properties and various maximum emission peaks owing to the different nature of the functional groups. Furthermore, the anti-microbial potential of ligands and complexes was evaluated with docking analyses carried out to investigate the binding affinity of terpyridine-based ligands along with corresponding proteins (shikimate dehydrogenase and penicillin-binding protein) binding sites. To obtain further insight into molecular orbital distributions and spectroscopic properties, density functional theory calculations were performed for representative complexes. The photophysical activity and interactions between chromophore structure and properties were both investigated experimentally as well as theoretically.

Synthesis, characterization, thermal properties and antiproliferative potential of copper(II) 4'-phenyl-terpyridine compounds

Reactions between 4'-phenyl-terpyridine (L) and several Cu(II) salts (p-toluenesulfonate, benzoate and o-, m- or p-hydroxybenzoate) led to the formation of [Cu(p-SO3C6H4CH3)L(H2O)2](p-SO3C6H4CH3) (1), [Cu(OCOPh)2L] (2), [Cu(o-OCOC6H4OH)2L] (3), [Cu(m-OCOC6H4OH)2L]4·MeOH (·MeOH) and [Cu(p-OCOC6H4OH)2L]5·2H2O (·2H2O), which were characterized by elemental and TG-DTA analyses, ESI-MS, IR spectroscopy and single crystal X-ray diffraction, as well as by conductivimetry. In all structures the Cu atoms present N3O3 octahedral coordination geometries, which, in 2-5, are highly distorted as a result of the chelating-bidentate mode of one of the carboxylate ligands. Intermolecular π···π stacking interactions could also be found in 2-5 (in the 3.569-3.651 Å range and involving solely the pyridyl rings). Medium-strong hydrogen bond interactions lead to infinite 1D chains (in 1 and 4) and to an infinite 2D network (in 5). Compounds 1 and 4 show high in vitro cytotoxicity towards HCT116 colorectal carcinoma and HepG2 hepatocellular carcinoma cell lines. The antiproliferative potential of compound 1 is due to an increase of the apoptotic process that was confirmed by Hoechst staining, flow cytometry and RT-qPCR. All compounds able to non-covalently intercalate the DNA helix and induce in vitro pDNA double-strand breaks in the absence of H2O2. Concerning compound 1, the hydroxyl radical and singlet oxygen do not appear to be involved in the pDNA cleavage process and the fact that this cleavage also occurs in the absence of molecular oxygen points to a hydrolytic mechanism of cleavage.

Coordination assemblies of the MII-tm/bpt (M = Zn/Cd/Co/Ni) mixed-ligand system: positional isomeric effect, structural diversification and properties

Six new coordination polymers with three positional isomeric bpt ligands and trimellitic acid (H₃tm), have been synthesized and characterized. They present diverse architectures. These results indicate that the versatile coordination modes of tm and the isomeric nature of bpt play crucial roles in modulating the structural topologies of these complexes.

Aqua-bis-(1,1,1,5,5,5-hexa-fluoro-acetyl-acetonato)[4'-(4-pyrid-yl)-2,2':6',2''-terpyridine]-ytterbium(III) chloride methanol monosolvate monohydrate

The title compound, [Yb(C₅HF₆O₂)₂(C₂₀H₁₄N₄)(H₂O)]Cl·CH₃OH·H₂O, adopts an eight-coordinated geometry around the Yb^III atom consisting of a 4′-(4-pyrid­yl)-2,2′:6′,2′′-terpyridine (pytpy) ligand, two 1,1,1,5,5,5-hexa­fluoro­acetyl­acetonate (hfac) anions and an aqua ligand. In the solid state, the compound forms supra­molecular chains running along the b-axis via inter­molecular hydrogen bonds between the Yb—OH₂ unit and the N-atom donor of the 4-pyridyl pendant of pytpy, with an O⋯N distance of 2.686 (4) Å. A chloride counter-anion and lattice methanol and water solvent mol­ecules occupy a hydro­philic columnar space along the coordination chains. O—H⋯Cl hydrogen bonds occur. The two water molecules and the four trifluoromethyl groups are disordered over two sets of sites, each with different occupancy ratios.

Poly[μ(2)-chlorido-dichlorido[μ(2)-4'-(4-pyrid-yl)-2,2':6',2''-terpyridine]-copper(I)copper(II)]

In the mixed-valence Cu^I/Cu^II coordination polymer, [Cu₂Cl₃(C₂₀H₁₄N₄)]_n, the two Cu atoms are bridged to a pair of Cl atoms across a centre of inversion. The monovalent metal atoms is coordinated by a pyridine N atom as well as by three Cl atoms in a tetra­hedral CuNCl₃ geometry. The divalent metal atom is N,N′,N′′-chelated by the heterocycle, and it exists in a square-pyramidal CuN₃Cl₂ geometry; the apical site is occupied by the second bridging Cl atom. The bridging modes of the Cl atoms and the heterocycle give rise to the formation of a layered arrangement parallel to (001).

Diiodido[4'-(4-pyrid-yl)-2,2':6',2''-terpyridine-κN,N',N'']copper(II)

The Cu(II) atom in the title compound, [CuI(2)(C(20)H(14)N(4))], has a distorted square-pyramidal coordination formed by the N atoms of the tridentate 4'-(4-pyrid-yl)-2,2':6'2''-terpyridine (pyterpy) ligand and two I atoms; one of the I atoms is in the apical position. In contrast to other known square-pyramidal diiodido- and dibromidocopper complexes of the pyterpy ligand in which metal-halogen distances are significantly different, in the title compound the apical and equatorial Cu-I bonds are almost identical [2.6141 (8) and 2.6025 (8) Å, respectively].