Search

Tris(pyrazolyl)methane (tpm), 2,2,2-tris(pyrazolyl)ethanol (tpmOH) and its esterification derivatives with ibuprofen and flurbiprofen (tpmIBU and tpmFLU) were used as ligands to obtain complexes of the type [Fe(tpmX)2]Cl2 (1–4). The tpmIBU and tpmFLU ligands and corresponding complexes 3 and 4 were characterized by IR and multinuclear NMR spectroscopy, and the structure of tpmIBU was elucidated by single crystal X-ray diffraction. Complexes 1–4 were also assessed for their behaviour in aqueous media (solubility in D2O, octanol/water partition coefficient, stability in physiological-like conditions). The antiproliferative activity of ligands and complexes was determined on A2780, A2780cis and A549 cancer cell lines and the non-cancerous HEK 293T and BJ cell lines. The ligands and complexes were investigated for their ability to inhibit COX-2 (cyclooxygenase) and HNE (4-hydroxynonenal) enzymes. Complexes 3 and 4 exhibited cytotoxicity that may be attributed predominantly to their bioactive fragments, while DNA binding and enhancement of ROS production do not appear to play any significant role. [ABSTRACT FROM AUTHOR]

In the synthesis of metal–organic frameworks (MOFs), the choice of the metal precursor plays a key role because of the influence that it can exert on the crystallization kinetics. The present work explores the use of metal-carbamato complexes for the synthesis of benchmark MOFs, namely HKUST-1 and UiO-66. Cu2(O2CNEt2)4·2NHEt2 and Zr(O2CNEt2)4, prepared using straightforward CO2 fixation reactions starting from the corresponding metal chlorides and diethylamine, were employed as metal precursors for MOF formation. The synthesis conditions, including the solvent, temperature, and ligand protonation degree, were systematically investigated, revealing metal carbamates as highly reactive precursors due to their prompt release of CO2 and amine upon reaction with protic species, i.e., the polycarboxylic linkers. This property of metal carbamates allowed us to identify room temperature protocols to achieve MOFs with comparable properties to those obtained using traditional metal precursors. Subsequent optimization of the reaction conditions led to the design of a one-pot synthetic strategy for HKUST-1, starting directly from copper(II) chloride and diethylamine under a CO2 atmosphere. The MOFs were characterized using various techniques, including powder X-ray diffraction, N2 sorption analysis, 1H nuclear magnetic resonance spectroscopy, and CHN elemental analysis, and compared to reference samples prepared according to literature procedures. [ABSTRACT FROM AUTHOR]

We present a new synthetic strategy for obtaining mixed-valence triiron complexes where the metal centers are bridged by a novel, highly functionalized hydrocarbyl ligand. The alkynyl–vinyliminium complexes [Fe2Cp2(CO)(μ-CO){μ-η1:η3-C(X–C≡CH)CHCNMe2}]CF3SO3 (X = 4-C6H4, [2a1]CF3SO3; X = (CH2)3, [2a2]CF3SO3) were synthesized in almost quantitative yields from the aminocarbyne precursor [Fe2Cp2(CO)2(μ-CO){μ-CNMe2}]CF3SO3, [1a]CF3SO3, and the di-alkynes HC≡C–X–C≡CH. Then, the ferracycle [Fe(Cp)(CO){C(NMe2)CH＝C(4-C6H4C≡CH)C(O)}], 4a1, was produced in 47% yield from the cleavage of [2a1]CF3SO3 promoted by pyrrolidine. Subsequent reactions of the acetonitrile adducts [Fe2Cp2(CO)(μ-CO)(NCMe){μ-CNMe(R)}]CF3SO3 (R = Me, [1aACN]CF3SO3; R = Xyl, [1bACN]CF3SO3) ([FeIFeI]) with 4a1 ([FeII]) at room temperature resulted in the formation of [FeIFeIFeII] complexes [Fe2Cp2(CO)(μ-CO){μ-η1:η3-C(X–C＝CHC(NMe2)＝FeCp(CO)C＝O)CHCNMe(R)}]CF3SO3 (R = Me, [5a1]CF3SO3; R = Xyl, [5b1]CF3SO3) in yields ranging from 56% to 64%. The new products were characterized by IR and multinuclear NMR spectroscopy, and the structures of [2a2]CF3SO3 and 4a1 were confirmed by single crystal X-ray diffraction. Cyclic voltammetry and spectroelectrochemical studies on [5a1]+ have revealed that reduction and oxidation events occur almost independently at the [FeIFeI] and [FeII] units, respectively. This observation underscores a minimal electronic interaction between the two fragments within the triiron complex. Accordingly, DFT studies pointed out that the HOMO and LUMO orbitals are predominantly localized in the two distinct compartments of [5a1]+. [ABSTRACT FROM AUTHOR]