A selective catalytic meta sulfonation of 2-phenylpyridines was found to occur in the presence of (arene)ruthenium(II) complexes upon reaction with sulfonyl chlorides. The 2-pyridyl group facilitates the formation of a stable Ru-C(aryl) σ bond that induces a strong para-directing effect. Electrophilic aromatic substitution proceeds with the sulfonyl chloride to furnish a sulfone at the position meta to the chelating group. This new catalytic process offers access to atypical regioselectivity for reactions involving chelation-assisted cyclometalation.
Six pharmaceutically relevant reactions covering a range of physical parameters have been investigated in a commercially available microwave flow reactor. The reaction conditions were scaled-up from tube or large batch scale microwave conditions, largely without change. Energy consumption measurements were also taken. In summary, this microwave flow reactor provided potentially successful manufacture for five out of six reactions investigated where homogeneous reactions solutions could be obtained. Production rates of between 0.5 and 3.0 mol/h (1-6 L/h) have been achieved with minimal redevelopment of the chemistry.
The synthesis of 4-phenyl-4H-arsolo[2,3-d:5,4-d′]bis(thiazole)
is reported,
and its properties are compared to those of the previously prepared
phosphole analogue. By comparison of their single-crystal structures,
the harmonic oscillator model of heterocyclic electron delocalization
(HOMHED) was used to directly compare the aromatic character of the
two systems. The findings demonstrate that, although both compounds
can be considered aromatic, the phosphole-containing compound had
a greater degree of aromatic character than its arsole analogue. The
arsole derivative exhibited excellent stability in ambient air with
no formation of the arsole oxide observed upon storage. The absorption
and photoluminescence spectra of the arsole derivate were subtly altered
in comparison to the phosphole derivative, suggesting that changing
pnictogenic atoms in such fused-ring systems to heavier analogues
could be a viable way of tuning both the ambient stability and optoelectronic
properties of such materials.
A model S(N)Ar reaction which gives a range of substituted diaryl ethers has been re-developed to function with the soluble organic base DBU in the place of insoluble potassium carbonate. Manufacture of these diaryl ethers has then been achieved by scaling-out in an automated stop-flow microwave reactor to give productivities of >0.5 kg per day. Analogous reaction partners have also been scaled up in this reactor to extend the scope of the study. Brief comparison in a scale-up batch microwave reactor is also made. Lastly, continuous 24 h processing is reported in this small microwave stop-flow reactor, which requires no manual intervention once started.
In order to investigate the solid-state light emission of zinc salphen macrocycle complexes, 7 dinuclear zinc salphen macrocycle complexes (1-7), with acetate or hexanoate coligands, are synthesized. The complexes are stable in air up to 300 °C, as shown via thermogravimetric analysis (TGA), and exhibit green to orange-red emission in solution (λ = 550-600 nm, PLQE ≤ 1%) and slightly enhanced yellow to orange-red emission in the solid state (λ = 570-625 nm, PLQE = 1-5%). Complexes 1, 2, 4, 5, and 7 also display aggregation-induced enhanced emission (AIEE) when hexane (a nonsolvent) is added to a chloroform solution of the complexes, with complex 4 displaying a 75-fold increase in peak emission intensity upon aggregation (in 0.25:0.75 chloroform:hexane mixture).
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