Synthesis and analysis of the anticancer activity of platinum(ii) complexes incorporating dipyridoquinoxaline variants

Eight platinum(ii) complexes with anticancer potential have been synthesised and characterised. These complexes are of the type [Pt(I)(A)], where I is either dipyrido[3,2-f:2′,3′-h]quinoxaline (dpq) or 2,3-dimethyl-dpq (23Medpq) and A is one of the R,R or S,S isomers of either 1,2-diaminocyclohexane (SS-dach or RR-dach) or 1,2-diaminocyclopentane (SS-dacp or RR-dacp). The CT-DNA binding of these complexes and a series of other complexes were assessed using fluorescent intercalator displacement assays, resulting in unexpected trends in DNA binding affinity. The cytotoxicity of the eight synthesised compounds was determined in the L1210 cell line; the most cytotoxic of these were [Pt(dpq)(SS-dach)]Cl and [Pt(dpq)(RR-dach)]Cl, with IC values of 0.19 and 0.80 μM, respectively. The X-ray crystal structure of the complex [Pt(dpq)(SS-dach)](ClO)·1.75HO is also reported. This journal i

Heteroatom substitution effects in spin crossover dinuclear complexes

We probe the effect of heteroatom substitution on the spin crossover (SCO) properties of dinuclear materials of the type [Fe2(NCX)4(R-trz)5]·S (X = S, Se; S = solvent; R-trz = (E)-N-(furan-2-ylmethylene)- 4H-1,2,4-triazol-4-amine (furtrz); (E)-N-(thiophen-2-ylmethylene)-4H-1,2,4-triazole-4-amine (thtrz)). For the furtrz family ([Fe2(NCX)4(furtrz)5]·furtrz·MeOH; X = S (furtrz-S) and X = Se (furtrz-Se)) gradual and incomplete one-step SCO transitions are observed (furtrz-S (T1/2 = 172 K) and furtrz-Se (T1/2 = 205 K)) and a structural evolution from [HS-HS] to [HS-LS] per dinuclear species. Contrasting this, within the thtrz family ([Fe2(NCX)4(thtrz)5]·4MeOH; X = S (thtrz-S) and X = Se (thtrz-Se)) more varied SCO transitions are observed, with thtrz-S being SCO-inactive (high spin) and thtrz-Se showing a rare complete two-step SCO transition (T1/2(1,2) = 170, 200 K) in which the FeII sites transition from [HS-HS] to [HS-LS] to [LS-LS] per dinuclear unit with no long range ordering of spin-states at the intermediate plateau. Detailed structure- function analyses have been conducted within this growing dinuclear family to rationalise these diverse spin-switching properties

Self-assembly of an imidazolate-bridged FeIII/CuII heterometallic cage

A rare, discrete, mixed-valent, heterometallic Fe(III)/Cu(II) cage, [CuFeL](ClO)χ solvent (HL = tris{[2-{(imidazole-4-yl)methylidene}amino]ethyl} amine), was designed and synthesized via metal-ion-directed self-assembly with neutral tripodal metalloligands. The formation of this coordination cage was demonstrated by X-ray crystallography, ESI mass spectrometry, FT-IR, and UV-vis-NIR spectroscopy

Structural diversity in coordination polymers constructed from a naphthalene-spaced dipyridyl ligand and iron(II) thiocyanate

Employing N,N'-bis-(4-pyridinylmethylene)-1,5-naphthalenediamine (nbpy4) and iron(II) thiocyanate as building blocks, three coordination polymers, [Fe(NCS)2(nbpy4)(MeOH)2]n, 1, [Fe(NCS)2(nbpy4)2]n_2nCHCl3_nH2O•2nEtOH, 2, and [Fe(NCS)2(nbpy4)(bpy)]n_2.5nDCM_0.75nH2O, 3, have been prepared. The three metal-organic materials were prepared by varying the solvent systems used and the inclusion of a second pyridine containing ligand (4,4′-bipyridine, bpy). Single crystal X-ray diffraction revealed 1 to be a one-dimensional structure with hydrogen bonding between adjacent chains and 2-3 to be two-dimension network solids with (4,4)-topologies

Self-assembly of a metallomacrocycle templated by iron(II)

An unusual discrete heteronuclear metallomacrocycle was designed and synthesized via metal-ion-directed self-assembly by an iron(II) template. The formation of this metallomacrocycle was demonstrated by X-ray crystallography, electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry, and NMR spectroscopy