title: Non-Switching 1,2-Dithienylethene-based Diplatinum(II) Complex Showing High Cytotoxicity.
abstract: A diplatinum(II) complex was prepared from a new 1,2-dithienylethene-based ligand containing N-methylimidazole groups as metal-binding units. Reaction of the ligand 1,2-bis[2-methyl-5-(1-methyl-1H-imidazol-2-yl)-3-thienyl]-cyclopentene (L2(H)) with cis-dichlorobis(dimethylsulfoxido)platinum(II) generated the bimetallic complex trans-[Pt2Cl4(DMSO)2(L2(H))] (DMSO = dimethyl sulfoxide), whose DNA-interacting properties were investigated using different techniques. Cytotoxicity assays with various cancer cell lines showed that this compound is active, with IC50 values in the micromolar range. Surprisingly, the diplatinum(II) complex does not exhibit the anticipated photoswitching properties; indeed, UV irradiation does not lead to the photocyclization of the ligand L2(H) or of the metal complex. Computational studies were performed and revealed significant differences in the electronic structure of L2(H) compared with L1(H) (i.e., 1,2-bis[2-methyl-5-(4-pyridyl)-3-thienyl]-cyclopentene, which exhibits photoswitching properties), in terms of the relevant molecular orbitals involved in the UV-vis absorption features, which ultimately is responsible for the inertia of L2(H) toward photocyclization.
authors.forename: Andreu
authors.initials: A
authors.lastname: Presa
authors.forename: Leoní
authors.initials: L
authors.lastname: Barrios
authors.forename: Jordi
authors.initials: J
authors.lastname: Cirera
authors.affiliation: Department of Pathology and Experimental Therapeutics, Faculty of Medicine, Universitat de Barcelona , Campus Bellvitge, Feixa Llarga s/n, 08907 L'Hospitalet de Llobregat, Spain.|Department of Medical Sciences, Institute for Research in Biomedicine, Health Sciences Program, University of Aveiro , Campus de Santiago, 3810-193 Aveiro, Portugal.
authors.forename: Luís
authors.initials: L
authors.lastname: Korrodi-Gregório
authors.affiliation: Department of Pathology and Experimental Therapeutics, Faculty of Medicine, Universitat de Barcelona , Campus Bellvitge, Feixa Llarga s/n, 08907 L'Hospitalet de Llobregat, Spain.
authors.forename: Ricardo
authors.initials: R
authors.lastname: Pérez-Tomás
authors.affiliation: Advanced Light Source, Lawrence Berkeley National Laboratory , 1 Cyclotron Road, Berkeley California 94720, United States.
authors.forename: Simon J
authors.initials: SJ
authors.lastname: Teat
authors.affiliation: Catalan Institution for Research and Advanced Studies , Passeig Lluís Companys 23, 08010 Barcelona, Spain.
authors.forename: Patrick
authors.initials: P
authors.lastname: Gamez