Molecular Meccano. 2. Self-Assembly of [n]Catenanes

Donor–Acceptor Oligorotaxanes Made to Order

“…Analysis of 2D NOESY spectra ( Figure 3 a and [3]pseudorotaxane assumes a folded conformation to maximize its p-p, C À H···p, and C À H···O interactions with [3]pseudorotaxane 3NP&(CBPQT·4 PF 6 ) 2 in a) space-filling and c) ball-and-stick representations. X-ray crystal superstructure of the analogous [2]pseudorotaxane reported previously [24] in b) space-filling and d) ball-and-stick representations. e) Space-filling and f) ball-and-stick representations of the energyminimized superstructure of the [3] [24] the solidstate superstructure of the [2]pseudorotaxane shown in Figure 4 b and d, which exhibits many of the same features, for example, folding of the polyether chain to maximize both p-p and C À H···O interactions in the 1:1 complex.…”

Design and Synthesis of Efficient Fluorescent Dyes for Incorporation into DNA Backbone and Biomolecule Detection

“…In Scheme 1, all precursor compounds with flexible ethylene glycol chains were synthesized (19,20) as the appropriate benzaldehyde 7 -14, which can be further condensed with ylids to make large π-conjugated systems. The experimental procedures for the synthesis are described in the experimental section.…”

“…After the stirring was continued overnight, the reaction solvent was removed in vacuum and the residue was directly subject to a silica gel column eluted with Cyclohexane/EtOAc (gradient elution with 1% Pyridine: 500/150 → 300/150 → 150/150, v/ v) to give the title product (800 mg, yield 90%): R f 0. 19 …”

A Kinetic Self‐Sorting Approach to Heterocircuit [3]Rotaxanes

“…The synthesis of heterocircuit rotaxanes in which several different rings are threaded onto asingle axle is complicated significantly by the potential for sequence isomerism:e ven with just two distinct macrocycles,aheterocircuit [3]rotaxane with an on-centrosymmetric axle exists as two isomers,a nd the stereochemical complexity rises as the number of rings increases. [1,2] Although the controlled synthesis of heterocircuit [n]catenanes is relatively well-developed, [3] including Stoddart and co-workerslandmark synthesis of olympiadane in 1994, [4] there remain relatively few examples of the synthesis of hetero[n]rotaxanes with control over the relative order of the macrocyclic components.…”

“…[5] Conceptually,t he simplest approach to the synthesis of heterocircuit [n]rotaxanes is to employ an axle with multiple orthogonal binding sites for the various rings that are then installed in as tepwise manner. [6] Alternative stepwise approaches to heterocircuit [n]rotaxanes have been developed;Sauvage and co-workers reported the coupling of kinetically inert pseudorotaxane complexes, [7] and in 2010 Leigh and co-workers used an iterative clipping of macrocycles around asingle binding site to produce both stereoisomers of a [3]rotaxane in astepwise manner. [6] Alternative stepwise approaches to heterocircuit [n]rotaxanes have been developed;Sauvage and co-workers reported the coupling of kinetically inert pseudorotaxane complexes, [7] and in 2010 Leigh and co-workers used an iterative clipping of macrocycles around asingle binding site to produce both stereoisomers of a [3]rotaxane in astepwise manner.…”