More Like this

1. Synthesis and Investigations of the Antitumor Effects of First-Row Transition Metal(II) Complexes Supported by Two Fluorinated and Non-Fluorinated β-Diketonates

   https://doi.org/10.3390/ijms25042038  

   Pellei, Maura; Del_Gobbo, Jo’; Caviglia, Miriam; Gandin, Valentina; Marzano, Cristina; Karade, Deepika V; Noonikara_Poyil, Anurag; Dias, H_V Rasika; Santini, Carlo (February 2024, International Journal of Molecular Sciences)

   The 3d transition metal (Mn(II), Fe(II), Co(II), Ni(II), Cu(II) and Zn(II)) complexes, supported by anions of sterically demanding β-diketones, 1,3-dimesitylpropane-1,3-dione (HLMes) and 1,3-bis(3,5-bis(trifluoromethyl)phenyl)-3-hydroxyprop-2-en-1-one (HLCF3), were synthesized and evaluated for their antitumor activity. To assess the biological effects of substituents on phenyl moieties, we also synthesized and investigated the analogous metal(II) complexes of the anion of the less bulky 1,3-diphenylpropane-1,3-dione (HLPh) ligand. The compounds [Cu(LCF3)2], [Cu(LMes)2] and ([Zn(LMes)2]) were characterized by X-ray crystallography. The [Cu(LCF3)2] crystallizes with an apical molecule of solvent (THF) and features a rare square pyramidal geometry at the Cu(II) center. The copper(II) and zinc(II) complexes of diketonate ligands, derived from the deprotonated 1,3-dimesitylpropane-1,3-dione (HLMes), adopt a square planar or a tetrahedral geometry at the metal, respectively. We evaluated the antitumor properties of the newly synthesized (Mn(II), Fe(II), Co(II), Ni(II), Cu(II) and Zn(II)) complexes against a series of human tumor cell lines derived from different solid tumors. Except for iron derivatives, cellular studies revealed noteworthy antitumor properties, even towards cancer cells endowed with poor sensitivity to the reference drug cisplatin. 

   more » « less
2. Ring Size Effects on Multi‐Stimuli Responsive Luminescent Properties of Cyclic Amine Substituted β‐Diketones and Difluoroboron Complexes

   https://doi.org/10.1002/asia.201801576  

   Wang, Fang; Song, Daniel; Dickie, Diane_A; Fraser, Cassandra_L (February 2019, Chemistry – An Asian Journal)

   Abstract Emissive β‐diketones (bdks) and difluoroboron complexes (BF₂bdks) show multi‐stimuli responsive luminescence in both solution and the solid state. A series of bdk ligands and boron coordinated dyes were synthesized with different cyclic amine substituents in the 4‐position to explore ring size effects on various luminescent properties, including solvatochromism, viscochromism, aggregation‐induced emission (AIE), mechanochromic luminescence (ML) and halochromism. Red‐shifted absorption and emission were observed in CH₂Cl₂for both bdk ligands and boron dyes with increasing substituent ring size. The compounds displayed bathochromic emission in more polar solvents, and higher fluorescence intensity in more viscous media. The AIE compounds exhibited enhanced emission when aggregated. For solid‐state properties, a large emission wavelength shift was shown for the piperidine substituted bdk after melt quenching on weighing paper. Large blue‐shifted emissions were observed in all the boron dye spin cast films after trifluoroacetic acid vapor annealing, and the original emissions were partially recovered after triethylamine vapor treatment. 

   more » « less
3. Metallacyclobuta‐(2,3)‐diene: A Bidentate Ligand for Stream‐line Synthesis of First Row Transition Metal Catalysts for Cyclic Polymerization of Phenylacetylene

   https://doi.org/10.1002/anie.202318956  

   Russell, John B; Konar, Debabrata; Keller, Taylor M; Gau, Michael R; Carroll, Patrick J; Telser, Joshua; Lester, Daniel W; Veige, Adam S; Sumerlin, Brent S; Mindiola, Daniel J (February 2024, Angewandte Chemie International Edition)

   Not, available (Ed.)

   Abstract Described here is a direct entry to two examples of 3d transition metal catalysts that are active for the cyclic polymerization of phenylacetylene, namely, [(BDI)M{κ²‐C,C‐(Me₃SiC₃SiMe₃)}] (2‐M) (BDI=[ArNC(CH₃)]₂CH⁻, Ar=2,6‐ⁱPr₂C₆H₃;M=Ti, V). Catalysts are prepared in one step by the treatment of [(BDI)MCl₂] (1‐M,M=Ti,V) with 1,3‐dilithioallene [Li₂(Me₃SiC₃SiMe₃)]. Complexes2‐Mhave been spectroscopically and structurally characterized and the polymers that are catalytically formed from phenylacetylene were verified to have a cyclic topology based on a combination of size‐exclusion chromatography (SEC) and intrinsic viscosity studies. Two‐electron oxidation of2‐Vwith nitrous oxide (N₂O) cleanly yields a [V^V] alkylidene‐alkynyl oxo complex [(BDI)V(=O){κ¹‐C‐(=C(SiMe₃)CC(SiMe₃))}] (3), which lends support for how this scaffold in2‐Mmight be operating in the polymerization of the terminal alkyne. This work demonstrates how alkylidynes can be circumvented using 1,3‐dianionic allene as a segue into M−C multiple bonds. 

   more » « less
4. Selective Macrocyclization of Unprotected Peptides with an Ex Situ Gaseous Linchpin Reagent

   https://doi.org/10.1002/anie.202405344  

   Ding, Yuxuan; Pedersen, Simon S; Wang, Haofan; Xiang, Baorui; Wang, Yixian; Yang, Zhi; Gao, Yuxiang; Morosan, Emilia; Jones, Matthew R; Xiao, Han; et al (July 2024, Angewandte Chemie International Edition)

   Abstract Peptide cyclization has dramatic effects on a variety of important properties, enhancing metabolic stability, limiting conformational flexibility, and altering cellular entry and intracellular localization. The hydrophilic, polyfunctional nature of peptides creates chemoselectivity challenges in macrocyclization, especially for natural sequences without biorthogonal handles. Herein, we describe a gaseous sulfonyl chloride derived reagent that achieves amine–amine, amine–phenol, and amine–aniline crosslinking through a minimalist linchpin strategy that affords macrocyclic urea or carbamate products. The cyclization reaction is metal‐mediated and involves a novel application of sulfine species that remains unexplored in aqueous or biological contexts. The aqueous method delivers unique cyclic or bicyclic topologies directly from a variety of natural bioactive peptides without the need for protecting‐group strategies. 

   more » « less
5. Tuning π-Acceptor/σ-Donor Ratio of the 2-Isocyanoazulene Ligand: Non-Fluorinated Rival of Pentafluorophenyl Isocyanide and Trifluorovinyl Isocyanide Discovered

   https://doi.org/10.3390/molecules26040981  

   Hart, Mason D.; Meyers, John J.; Wood, Zachary A.; Nakakita, Toshinori; Applegate, Jason C.; Erickson, Nathan R.; Gerasimchuk, Nikolay N.; Barybin, Mikhail V. (February 2021, Molecules)

   null (Ed.)

   Isocyanoazulenes (CNAz) constitute a relatively new class of isocyanoarenes that offers rich structural and electronic diversification of the organic isocyanide ligand platform. This article considers a series of 2-isocyano-1,3-X2-azulene ligands (X = H, Me, CO2Et, Br, and CN) and the corresponding zero-valent complexes thereof, [(OC)5Cr(2-isocyano-1,3-X2-azulene)]. Air- and thermally stable, X-ray structurally characterized 2-isocyano-1,3-dimethylazulene may be viewed as a non-benzenoid aromatic congener of 2,6-dimethyphenyl isocyanide (2,6-xylyl isocyanide), a longtime “workhorse” aryl isocyanide ligand in coordination chemistry. Single crystal X-ray crystallographic {Cr–CNAz bond distances}, cyclic voltametric {E1/2(Cr0/1+)}, 13C NMR {δ(13CN), δ(13CO)}, UV-vis {dπ(Cr) → pπ*(CNAz) Metal-to-Ligand Charge Transfer}, and FTIR {νN≡C, νC≡O, kC≡O} analyses of the [(OC)5Cr(2-isocyano-1,3-X2-azulene)] complexes provided a multifaceted, quantitative assessment of the π-acceptor/σ-donor characteristics of the above five 2-isocyanoazulenes. In particular, the following inverse linear relationships were documented: δ(13COtrans) vs. δ(13CN), δ(13COcis) vs. δ(13CN), and δ(13COtrans) vs. kC≡O,trans force constant. Remarkably, the net electron withdrawing capability of the 2-isocyano-1,3-dicyanoazulene ligand rivals those of perfluorinated isocyanides CNC6F5 and CNC2F3. 

   more » « less