Dimensional Matching of Polycyclic Aromatics with Rectangular Metallacycles: Insertion Modes Determined by [CH⋅⋅⋅π] Interactions

Abstract

A family of Pd(II)/Pt(II) dinuclear receptors, designed to give a smooth increase in their cavity lengths (from 7.46-13.78 Å), is presented. Their inclusion complexes with a representative set of polycyclic aromatic substrates (naphthalene, carbazol, pyrene, and benzo[a]pyrene), were characterized and studied in aqueous solution and the solid state. By taking into account the dimensions of both receptors and substrates, an excellent complementarity was found between the size of the receptors and their ability to complex a given substrate. Furthermore, this dimensional matching results in specific binding modes depending on the ability of the guest to establish stabilizing [C-H···π] interactions with the host.

Thinking Outside the “Blue Box”: Induced Fit within a Unique Self-Assembled Polycationic Cyclophane

“…The obtained data showed the host–guest complexation to be fast on the NMR time scale, allowing for its convenient fitting to a 1:1 association model using the software Dynafit . The obtained value of K a = 4960 ± 330 M –1 for W 2+ ⊂2,7-DHN is in good agreement with the reported values for similar systems. ,− …”

“…To improve to some extent some of the aforementioned drawbacks, and following our continuous interest in the development of self-assembled receptors in aqueous media, − we have turned our attention to the use of hydrazone-based dynamic covalent chemistry for the task . This methodology has very recently erupted in the literature, allowing the thermodynamically controlled preparation in aqueous media of entirely organic molecular receptors and mechanically interlocked molecules. − Even though the strategy has been proven quite successful, in most of the cases the amphiphilic character of the building blocks results rather in hydrophobically driven self-catenation or knotting − than into fully functional and empty kinetically stable hosts …”

Selective Separation of Polyaromatic Hydrocarbons by Phase Transfer of Coordination Cages

“…They are widespread pollutants, with many known to be carcinogenic, mutagenic, and teratogenic . Their rigid, planar, conjugated structures render them useful in the fabrication of optical and electronic devices. , Both the value of PAHs in pure form, and the problems they cause as pollutants, thus motivate the development of new host molecules − for selective PAH sequestration. − …”

Cucurbiturils as Effectors on the Self-Assembly of Pd(II) and Pt(II) Metallacycles

“…The CB[7] host was synthesized following a published procedure, and their purity was assessed as previously reported by our group . The dicationic ligands ( L1 2+ –L4 2+ ) were prepared as their nitrate salts using reported procedures. − Full synthetic details are given in the Experimental Section.…”