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In this proof-of-concept study, an active-template coupling is used to demonstrate a novel kinetic self-sorting process. This process iteratively increases the yield of the target heterocircuit [3]rotaxane product at the expense of other threaded species.

If at first you don't succeed, fall apart: A novel self-sorting approach is described in which the kinetic stability of the desired [3]rotaxane isomer determines the reaction outcome. All other threaded structures derived from the larger ring are kinetically unstable, allowing the yield of the target to be amplified at the expense of other possible products.

A stoichiometric C–H activation/decarbonylation of salicylaldehyde by [(η⁶-p-cymene)RuCl₂]₂ gave a carbonyl derivative [(η⁶-p-cymene)RuCl(CO)(Ph-O)] (1) without the use of CO gas. A variety of polar phosphines were then incorporated into compound 1 to give new Ru^II cationic catalysts, [(η⁶-p-cymene)Ru(CO)(Ph-O)L]BF₄ (2–8). These were used to catalyse the hydrothiolation of alkynes with a range of thiols in aqueous THF to give anti-Markovnikov E-linear vinyl sulfides in high yields.

A serendipitously discovered stoichiometric C–H activation/decarbonylation of salicylaldehyde by [(η⁶-p-cymene)RuCl₂]₂ gave [(η⁶-p-cymene)RuCl(CO)(Ph-O)] (1) without the need for external CO gas. Polar phosphines were incorporated into 1 to give cationic Ru^II catalysts 2–8. These were used in the hydrothiolation of alkynes to selectively give anti-Markovnikov E-linear vinyl sulfides in aq. THF.

A 14-membered heterocycle is created on the C₆₀ cage skeleton through a multistep procedure. Key steps involve repeated PCl₅-induced hydroxylamino N−O bond cleavage leading to insertion of nitrogen atoms, and also piperidine-induced peroxo O−O bond cleavage leading to insertion of oxygen atoms. The hetero atoms form one pyrrole, two pyran, and one diazepine rings in conjunction with the C₆₀ skeleton carbon atoms. The fullerene-based macrocycle showed unique reactivities towards fluoride ion and copper salts.

N,O your product: A N,O-heterocycle is created on the C₆₀ cage skeleton through a multistep procedure, which includes repeated PCl₅-induced hydroxylamino N−O bond cleavage leading to insertion of nitrogen atoms, and also piperidine-induced peroxo O−O bond cleavage leading to insertion of oxygen atoms. The fullerene based-macrocycle showed unique reactivity towards fluoride ion and copper salts.

The self-assembly in aqueous solution of the well-known cyclophane, cyclobis(paraquat-p-phenylene) (BB⁴⁺), and two cucurbit[7]uril (CB7) hosts around a simple hydroquinol-based, diamine guest (GH₂²⁺) was investigated by ¹H NMR and electronic absorption spectroscopies, electrospray mass spectrometry and DFT computations. The formation of a quaternary supramolecular assembly [GH₂²⁺⋅BB⁴⁺⋅ (CB7)₂] was shown to be a very efficient process, which takes place not only because of the attractive forces between each of the hosts and the guest, but also because of the lateral interactions between the hosts in the final assembly. This complementary set of attractive interactions results in clear cooperative binding effects that help overcome the entropic barriers for multiple component assembly.

A guest designed and synthesized to have three adjacent binding sites serves as the central component for the highly cooperative assembly of a novel quaternary supramolecular complex. Lateral interactions between the hosts in the final assembly contribute significantly to the cooperative binding.

A high potential donor–acceptor dyad composed of zinc porphyrin bearing three meso-pentafluorophenyl substituents covalently linked to C₆₀, as a novel dyad capable of generating charge-separated states of high energy (potential) has been developed. The calculated energy of the charge-separated state was found to be 1.70 eV, the highest reported for a covalently linked porphyrin–fullerene dyad. Intramolecular photoinduced electron transfer leading to charge-separated states of appreciable lifetimes in polar and nonpolar solvents has been established from studies involving femto- to nanosecond transient absorption techniques. The high energy stored in the form of charge-separated states along with its persistence of about 50–60 ns makes this dyad a potential electron-transporting catalyst to carry out energy-demanding photochemical reactions. This type of high-energy harvesting dyad is expected to open new research in the areas of artificial photosynthesis especially producing energy (potential) demanding light-to-fuel products.

Keep 'em separated: A donor–acceptor dyad composed of a high oxidation potential zinc porphyrin covalently linked to C₆₀ has been synthesized and shown to generate a high-energy charge-separated state on the order of 1.70 eV and a lifetime in the range of 50–60 ns during photoinduced electron transfer, which is sufficient to carry out many energy (potential) demanding photocatalytic reactions.

The synthesis of the first halogen bonding [3]rotaxane host system containing a bis-iodo triazolium-bis-naphthalene diimide four station axle component is reported. Proton NMR anion binding titration experiments revealed the halogen bonding rotaxane is selective for nitrate over the more basic acetate, hydrogen carbonate and dihydrogen phosphate oxoanions and chloride, and exhibits enhanced recognition of anions relative to a hydrogen bonding analogue. This elaborate interlocked anion receptor functions via a novel dynamic pincer mechanism where upon nitrate anion binding, both macrocycles shuttle from the naphthalene diimide stations at the periphery of the axle to the central halogen bonding iodo-triazolium station anion recognition sites to form a unique 1:1 stoichiometric nitrate anion–rotaxane sandwich complex. Molecular dynamics simulations carried out on the nitrate and chloride halogen bonding [3]rotaxane complexes corroborate the ¹H NMR anion binding results.

Anion sandwich is a pincer cake: The synthesis of the first halogen-bonding (XB) [3]rotaxane host system containing a four-station axle is reported. Anion-binding titration experiments reveal that the rotaxane is selective for nitrate and operates through a dynamic pincer mechanism in which both macrocycles shuttle to the central XB anion recognition sites to form a 1:1 stoichiometric oxoanion–rotaxane sandwich complex.

The self-assembly of higher-order anion helicates in solution remains an elusive goal. Herein, we present the first triple helicate to encapsulate iodide in organic and aqueous media as well as the solid state. The triple helicate self-assembles from three tricationic arylethynyl strands and resembles a tubular anion channel lined with nine halogen bond donors. Eight strong iodine⋅⋅⋅iodide halogen bonds and numerous buried π-surfaces endow the triplex with remarkable stability, even at elevated temperatures. We suggest that the natural rise of a single-strand helix renders its linear halogen-bond donors non-convergent. Thus, the stringent linearity of halogen bonding is a powerful tool for the synthesis of multi-strand anion helicates.

Bond, halogen bond: Three tricationic arylethynyl strands self-assemble to form a tubular anion channel lined with nine halogen-bond donors in solution and the solid state. Eight strong iodine⋅⋅⋅iodide halogen bonds and numerous buried π-surfaces endow the triplex with remarkable stability, even at elevated temperatures. The stringent linearity of halogen bonding could be a powerful tool for the synthesis of multi-strand anion helicates.