Three porous nanocarbons,1–3 that comprise pyrene,corannulene,and coronene cores encircled by cyclo-meta-phenylene(CMP)interconnections,have been synthesized and characterized.The interconnected CMPs caused different curvatures of the cores and imparted high solubility,large bathochromic shift,strong fluorescence,and low reduction potential to the systems.In solution,these porous nanocarbons existed as a complex mixture of dynamic processes that certainly influenced one another within any single molecule,leading to a set of rather simple proton nuclear magnetic resonance(^(1)H NMR)spectra.Single crystal X-ray diffraction and computational minimum energy analysis revealed the boatand saddle-like conformations of 1–3 in the solid state,significantly deviating from their conformations on the Au(111)surface.Furthermore,both 1 and 2 could form 2:1 complexes with C_(60),accompanied by adaptive geometry changes.In addition,1 served as a sky-blue emitter for an organic light-emitting diode(OLED).This work gives access and insights into a model system consisting of porous nanocarbons with intriguing supramolecular and optoelectronic properties.
Two novel polynuclear complexes{NaFe4(μ4-O)(L)4(μ2-Cl)[Fe(CN)_(5)NO](H_(2)O)(DMF)_(2)}(1)and{NaFe_(4)(μ4-O)(L)_(4)(μ2-OEt)[Fe(CN)_(5)NO](H_(2)O)(DMF)_(2)}(2)have been prepared using the tetradentate N-(2-hydroxy-ethyl)-3-methoxysalicylaldimine Schiff-base ligand(H2L)with the help of[Fe(CN)_(5)NO]_(2)-linkers,where the ligand was in situ synthesized through the condensation of o-vanillin and ethanolamine in the formation process of complexes.The resulting complexes possess“boat-like”structure constructed through three Fe ions and one Na ion with the fourth Fe ion acting as the“paddle”.The“hull bottom”contains an eight-membered metallamacrocycle with metalla-crown-like motif and[-M-O-]repeat unit.Both complexes display three-dimensional frameworks through C-H···N hydrogen bonds,C-H···Cl hydrogen bonds,andπ-πstacking interactions with the introduction of solvent molecules and coordination anions.Variable-temperature magnetic susceptibility measurements reveal strong antiferromagnetic couplings between the metal centers in complexes 1 and 2.
YANG NaYANG HuaTIAN Hai-QuanLI Da-ChengDOU Jian-Min
Polynuclear gold complexes show diverse structures and bonding.An exploration into their transformation represents a challenging area of research.Herein,an unprecedented substituent-mediated transformation from pentagold(I)to octadecagold(I)complexes has been observed.These gold(I)-sulfido complexes with distinct structures have been fully characterized,and the transformation process has been monitored by NMR spectroscopy in solution state.
Human metallothionein(MT)is a small-size yet efficient metal-binding protein,playing an essential role in metal homeostasis and heavy metal detoxification.MT contains two domains,each forming a polynuclear metal cluster with an exquisite hexatomic ring structure.The apoprotein is intrinsically disordered,which may strongly influence the clusters and the metal-thiolate(M-S)bonds,leading to a highly dynamic structure.However,these features are challenging to identify due to the transient nature of these species.The individual signal from dynamic conformations with different states of the cluster and M-S bond will be averaged and blurred in classic ensemble measurement.To circumvent these problems,we combined a single-molecule approach and multiscale molecular simulations to investigate the rupture mechanism and chemical stability of the metal cluster by a single MT molecule,focusing on the Zn4S11 cluster in theαdomain upon unfolding.Unusual multiple unfolding pathways and intermediates are observed for both domains,corresponding to different combinations of M-S bond rupture.None of the pathways is clearly preferred suggesting that unfolding proceeds from the distribution of protein conformational substates with similar M-S bond strengths.Simulations indicate that the metal cluster may rearrange,forming and breaking metal-thiolate bonds even when MT is folded independently of large protein backbone reconfiguration.Thus,a highly dynamic polynuclear metal cluster with multiple conformational states is revealed in MT,responsible for the binding promiscuity and diverse cellular functions of this metal-carrier protein.
