Λ-shaped optoelectronic materials based on Tröger’s base

Catalytic Asymmetric Synthesis of Tröger's Base Analogues with Nitrogen Stereocenter

Nitrogen stereocenters are common chiral units in natural products, pharmaceuticals, and chiral catalysts. However, their research has lagged largely behind, compared with carbon stereocenters and other heteroatom stereocenters. Herein, we report an efficient method for the catalytic asymmetric synthesis of Tröger's base analogues with nitrogen stereocenters via palladium catalysis and home-developed GF-Phos. It allows rapid construction of a new rigid cleft-like structure with both a C- and a N-stereogenic center in high efficiency and selectivity. A variety of applications as a chiral organocatalyst and metallic catalyst precursors were demonstrated. Furthermore, DFT calculations suggest that the NH···O hydrogen bonding and weak interaction between the substrate and ligand are crucial for the excellent enantioselectivity control.

Macrocyclic host molecules with aromatic building blocks: the state of the art and progress

Macrocyclic host molecules play the central role in host-guest chemistry and supramolecular chemistry. The highly structural symmetry of macrocyclic host molecules can meet people's pursuit of aesthetics in molecular design, and generally means a balance of design, synthesis, properties and applications. For macrocyclic host molecules with highly symmetrical structures, building blocks, which could be described as repeat units as well, are the most fundamental elements for molecular design. The structural features and recognition ability of macrocyclic host molecules are determined by the building blocks and their connection patterns. Using different building blocks, different macrocyclic host molecules could be designed and synthesized. With decades of developments of host-guest chemistry and supramolecular chemistry, diverse macrocyclic host molecules with different building blocks have been designed and synthesized. Aromatic building blocks are a big family among the various building blocks used in constructing macrocyclic host molecules. In this feature article, the recent developments of macrocyclic host molecules with aromatic building blocks were summarized and discussed.

Synthesis and Characterization of Macrocyclic Chiral Tröger's Base Phenhomazine Candidates as Anticancer Agent

1,4,7,10-Tetraoxa[10](2,8)trögerophane 5 was synthesized from its corresponding precursors. Heating of 2 with p-nitrophenoxide afforded bis(p-nitrophenyl)ether 3, which was treated with hydrazine hydrate to give bis(p-aminophenyl)ether 4. Treatment of 4 with paraformaldehyde and triflouroacetic anhydride gave trögerophane 5. Reaction of 5 with trifluroacetic anhydride afforded phenhomazine derivative 6, which was treated with potassium carbonate to afford tetrahydrophenhomazine 7. Finally, reaction of 7 with phenacylchloride, bromoacetic acid, or ethyl bromoacetate in the presence of triethyl amine under reflux, afforded the corresponding macrocyclic compounds 8, 9 and 10, respectively. The synthesized trögerophane,precursors and its newly synthesized phenhomazines derivatives were screened for anticancer activity. Results revealed that 1,4,7,10-tetraoxa[10](2,8)trögerophane had a promising selectivity towards colon cancer cell line with an IC₅₀ of 92.7 µg/ml.

One-pot facile synthesis of 4-amino-1,8-naphthalimide derived Tröger's bases via a nucleophilic displacement approach

We report here a novel one-pot synthetic strategy for the synthesis of a family of N-alkyl-1,8-naphthalimide derived Tröger's bases (in overall yield of 65–96%) via a nucleophilic substitution reaction.

An acidic pH fluorescent probe based on Tröger's base

A pH fluorescent probeTBPPincorporating an amine moiety and pyridine group through Tröger's base linker was designed and synthesized. The absorption and fluorescence titrations indicated that it can serve as a sensitive probe for pH measuring.

Crystal structure of 1,1′-diformyl-4,4′-(6H,12H-5,11-methano-dibenzo[b,f][11,5]diazocine-2,8-diyl)dibenzene, C29H22N2O2

C29H22N2O2, triclinic, P1̅ (no. 2), a = 22.4995(6) Å, b = 9.9370(3) Å, c = 21.6466(6) Å, β = 115.941(1)°, V = 4352.1(2) Å3, Z = 4, R gt (F) = 0.0487, wR ref (F 2 ) = 0.1473, T = 296 K.

Sensitivity of diamond-capped impedance transducer to Tröger's base derivative

Sensitivity of an intrinsic nanocrystalline diamond (NCD) layer to naphthalene Tröger's base derivative decorated with pyrrole groups (TBPyr) was characterized by impedance spectroscopy. The transducer was made of Au interdigitated electrodes (IDE) with 50 μm spacing on alumina substrate which were capped with the NCD layer. The NCD-capped transducer with H-termination was able to electrically distinguish TBPyr molecules (the change of surface resistance within 30-60 kΩ) adsorbed from methanol in concentrations of 0.04 mg/mL to 40 mg/mL. An exponential decay of the surface resistance with time was observed and attributed to the readsorption of air moisture after methanol evaporation. After surface oxidation the NCD cap layer did not show any leakage due to NCD grain boundaries. We analyzed electronic transport in the transducer and propose a model for the sensing mechanism based on surface ion replacement.

Click synthesis, aggregation-induced emission, E/Z isomerization, self-organization, and multiple chromisms of pure stereoisomers of a tetraphenylethene-cored luminogen

It has been difficult to decipher the mechanistic issue whether E/Z isomerization is involved in the aggregation-induced emission (AIE) process of a tetraphenylethene (TPE) derivative, due to the difficulty in the synthesis of its pure E and Z conformers. In this work, pure stereoisomers of a TPE derivative named 1,2-bis{4-[1-(6-phenoxyhexyl)-4-(1,2,3-triazol)yl]phenyl}-1,2-diphenylethene (BPHTATPE) are successfully synthesized. Both isomers show remarkable AIE effect (α(AIE) ≥ 322) and high fluorescence quantum yield in the solid state (Φ(F) 100%). The conformers readily undergo E/Z isomerization upon exposure to a powerful UV light and treatment at a high temperature (>200 °C). Such conformational change, however, is not observed under normal fluorescence spectrum measurement conditions, excluding the involvement of the E/Z isomerization in the AIE process of the TPE-based luminogen. The molecules of (E)-BPHTATPE self-organize into ordered one-dimensional nanostructures such as microfibers and nanorods that show obvious optical waveguide effect. BPHTATPE shows rich chromic effects, including mechano-, piezo-, thermo-, vapo-, and chronochromisms. Its emission peak is bathochromically shifted by simple grinding and pressurization and the spectral change is reversed by fuming with a polar solvent, heating at a high temperature, or storing at room temperature for some time. The multiple chromic processes are all associated with changes in the modes of molecular packing.

2,8-Dimesitylboranyl-6H,12H-5,11-methano-dibenzo[b,f][1,5]diazo-cine

In the title compound, C₅₁H₅₆B₂N₂, a substituted Tröger’s base, the dihedral angle between the two benzene rings constituting the Tröger’s base framework is 104.42 (6)°. The crystal structure is stabilized by C—H⋯π and weak C—H⋯N inter­actions.