Flavins─one of nature's most ubiquitous organic cofactors─mediate proton and electron transfers in biological systems. Their heterocyclic (iso)alloxazine cores enable such reactivity through pronounce Show more
Flavins─one of nature's most ubiquitous organic cofactors─mediate proton and electron transfers in biological systems. Their heterocyclic (iso)alloxazine cores enable such reactivity through pronounced electro- and photochemical properties, as well as hydrogen bonding with surrounding residues. To harness these features in an organometallic context, we developed a redox-active, flavin-derived bidentate ligand (allLH) that engages both primary and secondary coordination spheres. Coordination with Fe(II) yields an octahedral complex, (allLH)2FeX2 (X = Cl, Br, OTf), stabilized by outer-sphere hydrogen bonds between the ligand and metal-bound (pseudo)halides. Upon deprotonation, allLH undergoes tautomerization to the isoalloxazine form (isoL), generating a hydrogen-bonded aqua complex, (isoL)2Fe(OH2)2. Furthermore, treatment of (allLH)2FeCl2 with cobaltocene triggers ligand tautomerization, affording [(allLH)(isoL)FeCl2][CoCp2] and highlighting the redox-responsive nature of the flavin scaffold. This work introduces a novel approach to repurpose flavin as a multifunctional ligand platform for constructing tunable coordination environments around transition metal centers, offering new opportunities in ligand design and bioinspired reactivity. Show less
Mono or bis(tetrazole–thiolato) Pd(II) or Pt(II) complexes were obtained from the reactions of dialkyl Pd(II) or Pt(II) complexes with organic tetrazole–thiones (1-aryl- or 1-alkyl-1H-tetrazol Show more
Mono or bis(tetrazole–thiolato) Pd(II) or Pt(II) complexes were obtained from the reactions of dialkyl Pd(II) or Pt(II) complexes with organic tetrazole–thiones (1-aryl- or 1-alkyl-1H-tetrazole-5-thiones) via deprotonation. In contrast, equimolar reactions of zerovalent Pt(0) or Pd(0) complexes with organic tetrazole–thiones afforded hydrido or bis(tetrazole–thiolato) Pt(II) and Pd(II) complexes, and cyclometallated Pt(II) or Pd(II) complexes bearing a tetrazole–thiolato moiety via oxidative addition, depending on the organic substituents on the tetrazole–thiones. In particular, variable (time and temperature)-dependent 1H-NMR spectra of the hydrido Pt(II) tetrazole–thiolates reveal an upfield shift of the hydride signal, suggesting N,S-coordination behavior of the tetrazole–thiolato ligand. Additionally, the N-CH2 signal corresponds to the six-membered ring of platinacycle or palladacycle exhibiting geminal coupling with multiple protons and PR3 ligands; these coupling values were further determined using 1H{31P} experiments. Finally, treatment of the alkyl Pd(II) tetrazole–thiolate or Pd(II) bis(tetrazole–thiolates) with organic tert-butyl isocyanide, thiophenol, and organic halides caused the selective insertion of the isocyanide into the Pd–C bond or deprotonation to afford a Pd(II) disulfide complex and substitution to afford new organic tetrazolyl sulfides.
Show less
Highly ordered interactions between immune and metabolic responses are evolutionarily conserved and paramount for tissue and organismal health. Disruption of these interactions underlies the emergence Show more
Highly ordered interactions between immune and metabolic responses are evolutionarily conserved and paramount for tissue and organismal health. Disruption of these interactions underlies the emergence of many pathologies, particularly chronic non-communicable diseases such as obesity and diabetes. Here, we examine decades of research identifying the complex immunometabolic signaling networks and the cellular and molecular events that occur in the setting of altered nutrient and energy exposures and offer a historical perspective. Furthermore, we describe recent advances such as the discovery that a broad complement of immune cells play a role in immunometabolism and the emerging evidence that nutrients and metabolites modulate inflammatory pathways. Lastly, we discuss how this work may eventually lead to tangible therapeutic advancements to promote health. Show less
Mitochondrial Ca 2+ uptake plays a pivotal role both in cell energy balance and in cell fate determination. Studies on the role of mitochondrial Ca 2+ signaling in pathophysiology have been favored Show more
Mitochondrial Ca 2+ uptake plays a pivotal role both in cell energy balance and in cell fate determination. Studies on the role of mitochondrial Ca 2+ signaling in pathophysiology have been favored by the identification of the genes encoding the mitochondrial calcium uniporter (MCU) and its regulatory subunits. Thus, research carried on in the last years on one hand has determined the structure of the MCU complex and its regulation, on the other has uncovered the consequences of dysregulated mitochondrial Ca 2+ signaling in cell and tissue homeostasis. Whether mitochondrial Ca 2+ uptake can be exploited as a weapon to counteract cancer progression is debated. In this review, we summarize recent research on the molecular structure of the MCU, the regulatory mechanisms that control its activity and its relevance in pathophysiology, focusing in particular on its role in cancer progression. Show less