Shape-specific molecular assemblies require the preparation of the constituent building blocks with the necessary properties to bias exclusive formation of the proposed structures. In this work, a novel linear porphyrin dialdehyde was synthesised and used to assemble a supramolecular grid via Cu(I) heteroleptic phenanthroline/pyridyl imine complexation, and a tetrahedral cage via Fe(II) pyridyl imine coordination.

A multicomponent assembly is described resulting in [2] and [3]catenanes using three flexible components and three distinct noncovalent interactions. Despite the possibility of competing side-products, only the desired assemblies are generated and characterized spectroscopically.

This report examines the dynamics and the complexation behaviour of ‘acid porphyrin’ systems in solution and provides a valuable insight into the mechanisms for both porphyrin protonation and metallation. The synthesis of mono- and bis-substituted porphyrins appended with long alkyl chain fluorinated acids permitted intramolecular proton transfer to be observed and macrocyclic conformational control to be achieved. Furthermore, acid–porphyrin complexation is shown to be compatible with established metal–ligand interactions in the generation of novel supramolecular assemblies in solution.

In this report we use the weak interactions of acid–porphyrin complexes to selectively bind competing acids to the faces of a rigid cyclic porphyrin dimer, and characterise the resulting interactions by NMR spectroscopy and nano-electrospray ionisation spectrometry.

A variety of porphyrin-stoppered rotaxanes has been assembled under conditions of thermodynamic reversibility by judicious choice of components and temperatures. An admixture of a thread unit comprising a central naphthodiimide with terminal pyridines (2a), a ring unit dinaphtho-38-crown-10 (1) and either ZnII (3a), RuII (CO) (3b) or RhIII I (3c) as stoppers was shown to form an equilibrating mixture of pseudorotaxanes and the porphyrin-stoppered rotaxanes. The intact rotaxane could be crystallised from solution and chromatographed at low temperatures; at higher temperatures only a mixture of the components separated on chromatography. 1H NMR revealed NOE correlations between all three components for the rotaxane, and exchange peaks for related free and complexed species. The temperature and concentration dependence of the equilibria were studied by NMR methods, and van't Hoff plots for the Ru(CO) stoppered system enabled an estimation of ΔH° and ΔS°, −41.4 kJ mol−1, and −95 J K−1 mol−1, respectively, and a Ka at 273 K of 790 M−1, rising to 5.39 × 104 M−1 at 223 K. For the unstoppered pseudorotaxane systems 1–2a and 1–2b, the R ln K s. 1/T plots were not linear, implying a temperature-dependent ΔH and a non-zero ΔCp, indicative of a folding/unfolding of the extended thread unit on complexation. Nevertheless, although the thermodynamic stability of the overall rotaxane is expected to be comparable to that of the pseudorotaxane, there is clearly an enhanced kinetic barrier for formation of the metalloporphyrin-stoppered rotaxanes, but not for the more labile zinc analogue. While mixing of all three components of the rotaxanes at room temperature resulted in rapid rotaxane assembly irrespective of the order of addition (thermodyamic control), it was shown that at low temperatures it was possible to “lock out” or “lock on” the central thread unit under conditions of kinetic control. These concepts were further extended to the assembly of more complex multi-porphyrin arrays, where the central ring unit is a naphthocrown-strapped zinc porphyrin. It is therefore possible to use the kinetics of the remote event (metal ligation/coordination) to control the overall kinetics of rotaxane formation.

Shape-specific molecular assemblies require the preparation of the constituent building blocks with the necessary properties to bias exclusive formation of the proposed structures. In this work, a novel linear porphyrin dialdehyde was synthesised and used to assemble a supramolecular grid via Cu(I) heteroleptic phenanthroline/pyridyl imine complexation, and a tetrahedral cage via Fe(II) pyridyl imine coordination.

A multicomponent assembly is described resulting in [2] and [3]catenanes using three flexible components and three distinct noncovalent interactions. Despite the possibility of competing side-products, only the desired assemblies are generated and characterized spectroscopically.

In this report we use the weak interactions of acid–porphyrin complexes to selectively bind competing acids to the faces of a rigid cyclic porphyrin dimer, and characterise the resulting interactions by NMR spectroscopy and nano-electrospray ionisation spectrometry.

This report examines the dynamics and the complexation behaviour of ‘acid porphyrin’ systems in solution and provides a valuable insight into the mechanisms for both porphyrin protonation and metallation. The synthesis of mono- and bis-substituted porphyrins appended with long alkyl chain fluorinated acids permitted intramolecular proton transfer to be observed and macrocyclic conformational control to be achieved. Furthermore, acid–porphyrin complexation is shown to be compatible with established metal–ligand interactions in the generation of novel supramolecular assemblies in solution.