DABCO as a Dynamic Hinge between Cofacial Porphyrin Panels and Its Tumbling inside a Supramolecular Cavity

Abstract

The heteroleptic supramolecular double-decker porphyrin 1 was synthesized with DABCO as a guest between two cofacial porphyrin units as characterized by (1)H NMR and ESI-MS. While DABCO is not seen to tumble inside the cavity, even at higher temperatures (80 °C), such motion was triggered upon addition of various coordinating ligands (quinuclidine, 4-bromopyridine, or excess of DABCO). Different stoichiometric amounts were needed depending on the n donor quality of the added ligands to initiate tumbling of the "inside" DABCO. As demonstrated in an example with excess DABCO, the tumbling was stopped by lowering the temperature to -50 °C.

Palladium‐Catalysed Cross‐Coupling Reactions Controlled by Noncovalent Zn⋅⋅⋅N Interactions

“…The binding constants K 1.1 determined for 2 ⋅ A and 5 ⋅ A are only slightly higher compared to previous reports in which the titrations were performed using a different solvent; that is, dichloromethane . In the case of 6 ⋅ A , the binding constant compares well with the one observed between 6 and a zinc(II)–porphyrin similar to A . In all four cases ( 2 ⋅ A , 3 ⋅ A , 5 ⋅ A and 6 ⋅ A ), Job‐Plot analysis indicated the formation of discrete 1:1 self‐assembly species between A and 2 , 3 , 5 and 6 , respectively (see the Supporting Information)…”

Dynamic Functional Molecular Systems: From Supramolecular Structures to Multi‐Component Machinery and to Molecular Cybernetics

“…Following the same premises, four‐component nanorotors were prepared as well ,. Here, in extending the self‐sorting library in Scheme , the orthogonality of two additional dynamic interactions (see Chart 3 for HETPYP‐I: N py →[Cu(phenAr 2 )] + and N DABCO →ZnPor 2 ) is utilized in combination with cooperative effects . Obviously, without additional support, both homo‐ and heteromeric double deckers would emerge, but due to the cooperative effect of the HETPYP‐I interaction(s) (= C5 type motif) the hetero‐assembly 15 is furnished in quantitative yield (Scheme ).…”

“… Four‐component assembly (rotation is invisible to NMR). Porphyrin 13 represents the stator and 14 the rotator . For the complexation motifs, see Chart 3.…”

“…[Cu(phenAr 2 )] + and N DABCO !ZnPor 2 ) is utilized in combination with cooperative effects. [33] Obviously, without additional support, both homo-and heteromeric double deckers would emerge, but due to the cooperative effect of the HETPYP-I interaction(s) (= C5 type motif) the hetero-assembly 15 is furnished in quantitative yield (Scheme 2).…”

“…If both stations of the stator and both terminals of the rotator are identical as in 15, then rotation cannot be evaluated by VT 1 H NMR. [31,33] As a result, a variety of stators (with two or four phenanthroline stations) and desymmetrized rotators was probed. [31][32][33][34] In all cases, the four-component assemblies formed in a clean manner as they are held together by one or even several N py !…”