Synthesis and crystal structure of discrete complexes and coordination polymers containing 1,3-bis(pyrazol-1-yl)propane ligands

Biologically relevant unusual cooperative assemblies and fascinating infinite crown-like supramolecular nitrate–water hosts involving guest complex cations in bipyridine and phenanthroline-based Cu(ii) coordination compounds: antiproliferative evaluation and theoretical studies

Cytotoxicity in cancer cells with structure activity relationship has been explored in Cu(ii) compounds involving biologically relevant cooperative assemblies and fascinating crown-like nitrate–water hosts with guest complex cations.

The Early Years of 2,2'-Bipyridine-A Ligand in Its Own Lifetime

The first fifty years of the chemistry of 2,2′-bipyridine are reviewed from its first discovery in 1888 to the outbreak of the second global conflict in 1939. The coordination chemistry and analytical applications are described and placed in the context of the increasingly sophisticated methods of characterization which became available to the chemist in this time period. Many of the “simple” complexes of 2,2′-bipyridine reported in the early literature have been subsequently shown to have more complex structures.

Crystal structure of a Zn complex with tereph-thalate and 1,6-bis-(1,2,4-triazol-1-yl)hexa-ne

A new zinc coordination polymer with rigid benzene-1,4-di-carboxyl-ate (bdc) and flexible 1,6-bis-(1,2,4-triazol-1-yl)hexane (btrh), namely poly[[(μ2-benzene-1,4-di-carboxyl-ato)[μ2-1,6-bis-(1,2,4-triazol-1-yl)hexa-ne]zinc] di-methyl-form-amide monosolvate], [Zn(C8H4O4)(C10H16N6)]·C3H7NO, was synthesized. According to the single-crystal XRD analysis, the product crystallizes in the P-1 space group and has a layered structure. Analysis of the layered structure reveals {Zn(bdc)} chains which are connected by pairs of btrh ligands. The layers are packed tightly perpendicular to the [1-22] direction, separated by one non-disordered di-methyl-formamide solvent mol-ecule per formula unit. According to thermogravimetric analysis, the product completely loses this solvent at 453 K; the desolvated compound is stable up to 503 K. As a result of the lack of hydrogen-donor groups, hydrogen bonds are not observed in the structure of the complex; however, an inter-molecular C-H⋯π contact of 3.07 Å occurs.

Synthesis of tetrasubstituted pyrazoles containing pyridinyl substituents

A synthesis of tetrasubstituted pyrazoles containing two, three or four pyridinyl substituents is described. Hence, the reaction of 1,3-dipyridinyl-1,3-propanediones with 2-hydrazinopyridine or phenylhydrazine, respectively, affords the corresponding 1,3,5-trisubstituted pyrazoles. Iodination at the 4-position of the pyrazole nucleus by treatment with I2/HIO3 gives the appropriate 4-iodopyrazoles which served as starting materials for different cross-coupling reactions. Finally, Negishi cross-coupling employing organozinc halides and Pd catalysts turned out to be the method of choice to obtain the desired tetrasubstituted pyrazoles. The formation of different unexpected reaction products is described. Detailed NMR spectroscopic investigations (1H, 13C, 15N) were undertaken with all products prepared. Moreover, the structure of a condensation product was confirmed by crystal structure analysis.

X-ray crystallographic insights into post-synthetic metalation products in a metal-organic framework

Post-synthetic modification of metal-organic frameworks (MOFs) facilitates a strategic transformation of potentially inert frameworks into functionalized materials, tailoring them for specific applications. In particular, the post-synthetic incorporation of transition-metal complexes within MOFs, a process known as 'metalation', is a particularly promising avenue towards functionalizing MOFs. Herein, we describe the post-synthetic metalation of a microporous MOF with various transition-metal nitrates. The parent framework, 1: , contains free-nitrogen donor chelation sites, which readily coordinate metal complexes in a single-crystal to single-crystal transformation which, remarkably, can be readily monitored by X-ray crystallography. The presence of an open void surrounding the chelation site in 1: prompted us to investigate the effect of the MOF pore environment on included metal complexes, particularly examining whether void space would induce changes in the coordination sphere of chelated complexes reminiscent of those found in the solution state. To test this hypothesis, we systematically metalated 1: with first-row transition-metal nitrates and elucidated the coordination environment of the respective transition-metal complexes using X-ray crystallography. Comparison of the coordination sphere parameters of coordinated transition-metal complexes in 1: against equivalent solid- and solution-state species suggests that the void space in 1: does not markedly influence the coordination sphere of chelated species but we show notably different post-synthetic metalation outcomes when different solvents are used.This article is part of the themed issue 'Coordination polymers and metal-organic frameworks: materials by design'.