Dinuclear ytterbium(III) benzamidinate complexes with bridging S32-, Se22- and Te22- ligands: synthesis, structure and magnetic properties

Treatment of Yb(II) complex [L2Yb(THF)2] (L = PhC(NSiMe3)2) with elemental sulfur, selenium or tellurium resulted in the isolation of a series of dinuclear Yb(III) complexes featuring side-on bound S32- (1), Se22- (2) or Te22- (3) moieties, respectively. Magnetic study on these complexes revealed that 3 is a rare lanthanide telluride single-molecule magnet (SMM).

Rare-earth metal complexes with redox-active formazanate ligands

The synthesis and characterisation of rare-earth metal complexes with redox-active formazanate ligands are described. Deprotonation of the neutral formazan ligand L¹H (L¹ = PhNNC(Ph)NNPh) with [Ln{N(SiMe₃)₂}₃] (Ln = Y, Sm, Dy) resulted in homoleptic tris(formazanate) complexes with the general formula [(L¹)₃Ln] (Ln = Y (1), Sm (2), Dy (3)), in which the central metal atom is coordinated by six N atoms, revealing a propeller-type structure. To generate heteroleptic complexes, a novel formazan ligand L²H (L² = {PhNNC(4-tBuPh)NNPh}) was employed. Salt metathesis by using the trivalent precursors [SmCp*₂(μ-Cl)₂K(thf)] (Cp* = η⁵-C₅Me₅) or [LnCp₂Cl]₂ (Cp = η⁵-C₅H₅, Ln = Dy, Yb) and [L²K(thf)] formed mono(formazanate) complexes, [L²SmCp*₂] (4) and [L²LnCp₂] (Ln = Dy (5), Yb (6)), respectively. Unexpectedly, a redox reaction occurred between [L²K(thf)] and the divalent ytterbium precursor, [YbI₂(thf)₂], generating the trivalent ytterbium complex [(L²)₃Yb] (7). When the neutral formazan ligand (L2H) reacted with [SmCp*₂(thf)₂], the oxidised samarium complex 4 was formed. These novel compounds were fully characterised and their electrochemical properties were explored by cyclic voltammetry.

Photoluminescence with an unusual open-loop and rigid delocalized conjugated structure in quantum dots

It is well known that almost all photoluminescent molecules are aromatic or heterocyclic ring compounds for bioimaging analysis. A question remains as to whether a breakthrough can be achieved regarding a novel photoluminescent molecule without a ring structure, and in a what manner. In this study, we explored the photoelectric conversion and structure of photoluminescent compounds, and constructed an intra-molecular coupling positive-negative-junction (PNJ) with an open-loop and rigid Π₅⁶ delocalized conjugated structure of the coupling p-π conjugate system. This was performed to enable strong absorption of the R/tail-end band for the high probability of an n → π*/n → σ* electron transition for photoluminescence production. Subsequently, the Π₅⁶ structure was formed in a short-chain aliphatic molecule as a hydrolytic product of citric acid and urea, and computational methodology was employed to estimate the feasibility of the molecule photoluminescence. Finally, a quantum dot material was fabricated from the aliphatic molecule, the optical properties of the quantum dots were investigated, and the biocompatibility and bioimaging ability of quantum dots were assessed. This work presents not only a theoretical exploration but also practical application of a new strategy to obtain molecules, compounds, and materials with bioimaging.

FLP-catalysis meets hydrogen-bond activation

The potential of two chiral amidines and three non-chiral boranes in the metal-free hydrogen activation was explored.