Mechanical interlocking of SWNTs with N-rich macrocycles for efficient ORR electrocatalysis.

Substitutional N-doping of single-walled carbon nanotubes is a common strategy to enhance their electrocatalytic properties in the oxygen-reduction reaction (ORR). Here, we explore the encapsulation of SWNTs within N-rich macrocycles as an alternative strategy to display electroactive sites on the surface of SWNTs. We design and synthesize four types of mechanically interlocked derivatives of SWNTs (MINTs) by combining two types of macrocycles and two types of SWNT samples. Comprehensive electrochemical characterization of these MINTs and their reference SWNTs allows us to establish structure-activity relationships. First, we show that all MINT samples are superior electrocatalysts compared to pristine SWNTs, which serves as general validation of our strategy. Secondly, we show that macrocycles displaying both N atoms and carbonyl groups perform better than those with N atoms only. Finally, we demonstrate that a tighter fit between macrocycles and SWNTs results in enhanced catalytic activity and stability, most likely due to a more effective charge-transfer between the SWNTs and the macrocycles. These results, focusing on the ORR as a testbed, show the possibility of understanding electrocatalytic performance of SWNTs at the molecular level and thus enable the design of more active and more stable catalysts in the future.

Development of novel theranostic agents for in vivo amyloid imaging and protective effects on human neuroblastoma cells.

Brain amyloid deposits have been identified as the main neuropathological hallmarks of Alzheimer's diseases (AD) and intensive efforts have been devoted to develop aggregation inhibitors preventing the formation of toxic oligomeric Aß for therapeutic. In addition, evidence indicates that the formation and accumulation of ß-amyloid plaques probably precede clinical symptoms by around 20 years and imaging of such plaques would be beneficial for early-stage AD detection. In this study, we investigated phenothiazine-based compounds as novel promising theranostic agents for AD. These multifunctional agents exhibited BBB permeability, low neurotoxicity, good bio-stability as well as strong turn-on fluorescence with a Stokes shift upon binding to Aß aggregates. They had metal-chelating property which could delay Aß aggregation and displayed high binding affinity for ß-amyloid aggregates. Moreover, they have been simultaneously applied to perform in vivo near-infrared fluorescence imaging of ß-amyloid plaques in double transgenic AD mouse model, to prevent self-aggregation of Aß monomer from forming toxic oligomers and to protect human neuroblastoma SH-SY5Y cells against Aß-induced toxicity and oxidative stress.

syn-BN-heteroacene cored conjugated oligomers with finely tuned blue-violet luminescent properties.

Initiated by the effective dibromination of syn-BN-heteroacenes, a series of BN-containing conjugated oligomers was successfully synthesized upon transition-metal-catalyzed cross coupling. Their electronic structures can be finely tailored through varying the fused backbone or terminal substituents, endowing them with tunable luminescent properties within blue-violet regions.

Angular BN-Heteroacenes with syn-Structure-Induced Promising Properties as Host Materials of Blue Organic Light-Emitting Diodes.

A series of novel angular BN-heteroacenes were successfully synthesized. Associated with the intrinsic syn-structures, they exhibit unique molecular alignments in a solid state and promising electronic properties, and are thus suitable as efficient nondoped emitters for the fabrication of blue organic light-emitting diodes with improved performance.

Synthesis and Properties of C(2h)-Symmetric BN-Heteroacenes Tailored through Aromatic Central Cores.

The 2-fold successive electrophilic borylation on one aromatic central core led to a series of C(2h)-symmetric BN-heteroacenes in excellent yields. For the first time, we introduced trimethylsilyl (TMS) as either leaving group or oriented group for efficiently improving the preparation of BN-embedded polycyclic aromatic hydrocarbons (PAHs). The physical properties of the as-synthesized BN-heteroacenes in either solid state or solution can be finely tuned through the position isomerization or the fused ring numbers of the aromatic central core.

Synthesis and structural characterization of binuclear half-sandwich iridium, rhodium and ruthenium complexes containing 4,4'-dipyridyldisulfide (4DPDS) ligands.

Reactions of half-sandwich iridium and rhodium complexes [Cp*MCl2]2 (1a: M = Ir, 1b: M = Rh) and the half-sandwich ruthenium complex [(p-cymene)RuCl2]2 (1c) with 4DPDS gave the corresponding binuclear complexes [{Cp*MCl2]2}(m-4DPDS) (2a: M = Ir, 2b: M = Rh) and [{(p-cymene)RuCl2]2}(m-4DPDS) (2c), which can be converted into binuclear metallamacrocycles. The metallamacrocycles [Cp*M(m-4DPDS)Cl]2(2+) (3a: M = Ir, 3b: M = Rh) and [(p-cymene)Ru(m-4DPDS)Cl]2(2+) (3c) are composed of two half-sandwich units and two 4DPDS ligands with the same chirality. The macrocycle 3c is chiral and changes its shape slightly depending on the guests accommodated above and below the cavities.

Synthesis and characterization of molecular rectangles of half-sandwich p-cymene ruthenium complexes bearing oxamidato ligands.

A series of binuclear half-sandwich p-cymene ruthenium complexes bearing oxamidato ligands [(p-cymene)(2)Ru(2)(mu-N,N'-bis(aryl)oxamidato)Cl(2)] (1-3) was synthesized by the reactions of the lithium salts of oxamide with [(p-cymene)RuCl(2)](2), respectively. Treatment of the binuclear complexes (1-3) with bidentate ligands such as 4,4'-bipyridine (4,4'-bpy) and trans-1,2-bis(4-pyridyl)ethylene (bpe) in the presence of AgOTf (OTf = CF(3)SO(3)) gave the corresponding tetranuclear complexes generally formulated as [(p-cymene)(4)Ru(4)(mu-N,N'- bis(aryl)oxamidato)(2)(mu-4,4'-bpy)(2)](OTf)(4) (4a-c) and [(p-cymene)(4)Ru(4)(mu-N,N'-bis(aryl)oxamidato)(2)(mu-bpe)(2)](OTf)(4) (5a-c) in high yields. All compounds (1-3, 4a-5c) have been characterized by NMR and IR spectra and elemental analyses. The molecular structures of , and have been determined by single-crystal X-ray analyses. The molecular structures of tetranuclear complexes and showed that two binuclear fragments as building blocks were connected by 4,4'-bpy or bpe to construct a rectangular cavity with the dimensions 5.57 x 11.28 A (4a) and 5.56 x 13.65 A (5a).