Abraha Habtemariam

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Organization: University of Warwick , England

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Title: (PhD)

Chemicals
References

Upconverting Nanoparticles Prompt Remote Near-Infrared Photoactivation of Ru(II)Arene Complexes

Co-reporter:Emmanuel Ruggiero;Dr. Claudio Garino; Juan C. Mareque-Rivas;Dr. Abraha Habtemariam;Dr. Luca Salassa

Chemistry - A European Journal 2016 Volume 22( Issue 8) pp:2801-2811

Publication Date(Web):

DOI:10.1002/chem.201503991

Abstract

The synthesis and full characterisation (including X-ray diffraction studies and DFT calculations) of two new piano-stool Ru^II–arene complexes, namely [(η⁶-p-cym)Ru(bpy)(m-CCH-Py)][(PF)₆]₂ (1) and [(η⁶-p-cym)Ru(bpm)(m-CCH-Py)][(PF)₆]₂ (2; p-cym=p-cymene, bpy=2,2′-bipyridine, bpm=2,2′-bipyrimidine, and m-CCH-Py=3-ethynylpyridine), is described and discussed. The reaction of the m-CCH-Py ligand of 1 and 2 with diethyl-3-azidopropyl phosphonate by Cu-catalysed click chemistry affords [(η⁶-p-cym)Ru(bpy)(P-Trz-Py)][(PF)₆]₂ (3) and [(η⁶-p-cym)Ru(bpm)(P-Trz-Py)][(PF)₆]₂ (4; P-Trz-Py=[3-(1-pyridin-3-yl-[1,2,3]triazol-4-yl)-propyl]phosphonic acid diethyl ester). Upon light excitation at λ=395 nm, complexes 1–4 photodissociate the monodentate pyridyl ligand and form the aqua adduct ions [(η⁶-p-cym)Ru(bpy)(H₂O)]²⁺ and [(η⁶-p-cym)Ru(bpm)(H₂O)]²⁺. Thulium -doped upconverting nanoparticles (UCNPs) are functionalised with 4, thus exploiting their surface affinity for the phosphonate group in the complex. The so-obtained nanosystem UCNP@4 undergoes near-infrared (NIR) photoactivation at λ=980 nm, thus producing the corresponding reactive aqua species that binds the DNA-model base guanosine 5′-monophosphate.

Bipyrimidine ruthenium(II) arene complexes: structure, reactivity and cytotoxicity

Co-reporter:Soledad Betanzos-Lara;Olga Novakova

JBIC Journal of Biological Inorganic Chemistry 2012 Volume 17( Issue 7) pp:1033-1051

Publication Date(Web):2012 October

DOI:10.1007/s00775-012-0917-9

The synthesis and characterization of complexes [(η6-arene)Ru(N,N′)X][PF6], where arene is para-cymene (p-cym), biphenyl (bip), ethyl benzoate (etb), hexamethylbenzene (hmb), indane (ind) or 1,2,3,4-tetrahydronaphthalene (thn), N,N′ is 2,2′-bipyrimidine (bpm) and X is Cl, Br or I, are reported, including the X-ray crystal structures of [(η6-p-cym)Ru(bpm)I][PF6], [(η6-bip)Ru(bpm)Cl][PF6], [(η6-bip)Ru(bpm)I][PF6] and [(η6-etb)Ru(bpm)Cl][PF6]. Complexes in which N,N′ is 1,10-phenanthroline (phen), 1,10-phenanthroline-5,6-dione or 4,7-diphenyl-1,10-phenanthroline (bathophen) were studied for comparison. The RuII arene complexes undergo ligand-exchange reactions in aqueous solution at 310 K; their half-lives for hydrolysis range from 14 to 715 min. Density functional theory calculations on [(η6-p-cym)Ru(bpm)Cl][PF6], [(η6-p-cym)Ru(bpm)Br][PF6], [(η6-p-cym)Ru(bpm)I][PF6], [(η6-bip)Ru(bpm)Cl][PF6], [(η6-bip)Ru(bpm)Br][PF6] and [(η6-bip)Ru(bpm)I][PF6] suggest that aquation occurs via an associative pathway and that the reaction is thermodynamically favourable when the leaving ligand is I > Br ≈ Cl. pKa* values for the aqua adducts of the complexes range from 6.9 to 7.32. A binding preference for 9-ethylguanine (9-EtG) compared with 9-ethyladenine (9-EtA) was observed for [(η6-p-cym)Ru(bpm)Cl][PF6], [(η6-hmb)Ru(bpm)Cl]+, [(η6-ind)Ru(bpm)Cl]+, [(η6-thn)Ru(bpm)Cl]+, [(η6-p-cym)Ru(phen)Cl]+ and [(η6-p-cym)Ru(bathophen)Cl]+ in aqueous solution at 310 K. The X-ray crystal structure of the guanine complex [(η6-p-cym)Ru(bpm)(9-EtG-N7)][PF6]2 shows multiple hydrogen bonding. Density functional theory calculations show that the 9-EtG adducts of all complexes are thermodynamically preferred compared with those of 9-EtA. However, the bmp complexes are inactive towards A2780 human ovarian cancer cells. Calf thymus DNA interactions for [(η6-p-cym)Ru(bpm)Cl][PF6] and [(η6-p-cym)Ru(phen)Cl][PF6] consist of weak coordinative, intercalative and monofunctional coordination. Binding to biomolecules such as glutathione may play a role in deactivating the bpm complexes.