0000000001303511
AUTHOR
Alexander Roller
Incorporation of CrIII into a Keggin Polyoxometalate as a Chemical Strategy to Stabilize a Labile {CrIIIO4} Tetrahedral Conformation and Promote Unattended Single-Ion Magnet Properties
Polyoxometalates (POMs) provide rigid and highly symmetric coordination sites and can be used as a strategy for the stabilization of magnetic ions. Herein, we report a new member of the Keggin archetype, the Cr-centered Keggin anion [α-CrW12O40]5– (CrW12), with the unusual tetrahedral coordination of CrIII reported for the first time in POMs conferring unattended magnetic properties. POM chemistry has recently presented excellent examples of single-molecule and single-ion magnets (SMMs and SIMs) as well as molecular spin qubits; however, the majority of POM-based SIMs reported to date contain lanthanoid ions. CrW12, as the first example of a chromium(III) SIM, exhibits slow relaxation of ma…
Halogen‐Imparted Reactivity in Lithium Carbenoid Mediated Homologations of Imine Surrogates: Direct Assembly of bis‐Trifluoromethyl‐β‐Diketiminates and the Dual Role of LiCH 2 I
The selective formal insertion (homologation) of a carbon unit bridging the two trifluoroacetamidoyl chlorides (TFAICs) units is reported. The tactic is levered on a highly chemoselective homologation-metalation-acyl nucleophilic substitution sequence which precisely enables to assemble novel trifluoromethylated β-diketiminates within a single synthetic operation. Unlike previous homologations conducted with LiCH2Cl furnishing aziridines, herein we exploit the unique capability of iodomethyllithium to act contemporaneously as a C1 source (homologating effect) and metalating agent. The mechanistic rationale grounded on experimental evidences supports the hypothesized proposal and, the struct…
Ruthenium-arene complexes bearing naphthyl-substituted 1,3-dioxoindan-2-carboxamides ligands for G-quadruplex DNA recognition.
Quadruplex nucleic acids – DNA/RNA secondary structures formed in guanine rich sequences – proved to have key roles in the biology of cancers and, as such, in recent years they emerged as promising targets for small molecules. Many reports demonstrated that metal complexes can effectively stabilize quadruplex structures, promoting telomerase inhibition, downregulation of the expression of cancer-related genes and ultimately cancer cell death. Although extensively explored as anticancer agents, studies on the ability of ruthenium arene complexes to interact with quadruplex nucleic acids are surprisingly almost unknown. Herein, we report on the synthesis and characterization of four novel Ru(…
Another step toward DNA selective targeting: NiII and CuII complexes of a Schiff base ligand able to bind gene promoter G-quadruplexes
DNA G-rich sequences are able to form four-stranded structures organized in stacked guanine tetrads. These structures, called G-quadruplexes, were found to have an important role in the regulation of oncogenes expression and became, for such a reason, appealing targets for anticancer drugs. Aiming at finding selective G-quadruplex binders, we have designed, synthesized and characterized a new water soluble Salen-like Schiff base ligand and its NiII and CuII metal complexes. UV-Vis, circular dichroism and FRET measurements indicated that the nickel complex can stabilize oncogene promoter G-quadruplexes with high selectivity, presenting no interactions with duplex DNA at all. The same compoun…
Spontaneous Resolution of a Triple‐Stranded Dinickel(II) Helicate Generated via Intermolecular Transamination Reaction of S ‐Methylisothiocarbohydrazide in the Presence of Ni 2+
The reaction of S-methylisothiocarbohydrazide hydroiodide [H2NNHC(SCH3)NNH2·HI] with NiCl2·6H2O in water at room temperature yielded a triple-stranded dinickel(II) helicate [NiII(L1–L1)3NiII]I4·4H2O (14+·4I–·4H2O), where L1–L1 = H2NNHC(SCH3)NNC(SCH3)NHNH2, in 35 % yield, which spontaneously separates in enantiomers upon crystallization. The enantiomers do not racemize at room temperature, even not after 15 h of heating at 90 °C. X-ray diffraction structures of both enantiomers, chiroptical and magnetic properties of 14+·4I–·4H2O are reported. Demetallation of the complex by treatment with S2– resulted in 3,6-bis(methylthio)-1,4-dihydro-1,2,4,5-tetrazine (2). Compound 2 undergoes 2-e– oxidat…
CCDC 1451695: Experimental Crystal Structure Determination
Related Article: Alessio Terenzi, Daniela Lötsch, Sushilla van Schoonhoven, Alexander Roller, Christian R. Kowol, Walter Berger, Bernhard K. Keppler, Giampaolo Barone|2016|Dalton Trans.|45|7758|doi:10.1039/C6DT00648E
CSD 1913668: Experimental Crystal Structure Determination
Related Article: Nadiia I. Gumerova, Alexander Roller, Gerald Giester, J. Krzystek, Joan Cano, Annette Rompel|2020|J.Am.Chem.Soc.|142|3336|doi:10.1021/jacs.9b12797
CCDC 1870492: Experimental Crystal Structure Determination
Related Article: Laura A. Hager, Stephan Mokesch, Claudia Kieler, Silvia Alonso-de Castro, Dina Baier, Alexander Roller, Wolfgang Kandioller, Bernhard K. Keppler, Walter Berger, Luca Salassa, Alessio Terenzi|2019|Dalton Trans.|48|12040|doi:10.1039/C9DT02078K
CCDC 1451694: Experimental Crystal Structure Determination
Related Article: Alessio Terenzi, Daniela Lötsch, Sushilla van Schoonhoven, Alexander Roller, Christian R. Kowol, Walter Berger, Bernhard K. Keppler, Giampaolo Barone|2016|Dalton Trans.|45|7758|doi:10.1039/C6DT00648E
CCDC 1451696: Experimental Crystal Structure Determination
Related Article: Alessio Terenzi, Daniela Lötsch, Sushilla van Schoonhoven, Alexander Roller, Christian R. Kowol, Walter Berger, Bernhard K. Keppler, Giampaolo Barone|2016|Dalton Trans.|45|7758|doi:10.1039/C6DT00648E
CCDC 1870494: Experimental Crystal Structure Determination
Related Article: Laura A. Hager, Stephan Mokesch, Claudia Kieler, Silvia Alonso-de Castro, Dina Baier, Alexander Roller, Wolfgang Kandioller, Bernhard K. Keppler, Walter Berger, Luca Salassa, Alessio Terenzi|2019|Dalton Trans.|48|12040|doi:10.1039/C9DT02078K
CCDC 2007131: Experimental Crystal Structure Determination
Related Article: Laura Ielo, Laura Castoldi, Saad Touqeer, Jessica Lombino, Alexander Roller, Cristina Prandi, Wolfgang Holzer, Vittorio Pace|2020|Angew.Chem.,Int.Ed.|59|20852|doi:10.1002/anie.202007954
CCDC 1870493: Experimental Crystal Structure Determination
Related Article: Laura A. Hager, Stephan Mokesch, Claudia Kieler, Silvia Alonso-de Castro, Dina Baier, Alexander Roller, Wolfgang Kandioller, Bernhard K. Keppler, Walter Berger, Luca Salassa, Alessio Terenzi|2019|Dalton Trans.|48|12040|doi:10.1039/C9DT02078K