Synthesis, Structure and Photophysics of Neutral π-Associated [2]Catenanes

Abstract

Three neutral π‐associated [2]catenanes have been synthesised from the oxidative dimerisation of terminal acetylene‐equipped electron‐deficient diimides in the presence of an electron‐rich dinaptho‐crown template (below). The mutual recognition of the complementary donor–acceptor building blocks is revealed in solid‐state analyses of a precatenane inclusion complex and a [2]catenane. Dynamic movement of the interlocked rings has been examined by 1H NMR spectroscopy, and a model has been developed to explain the observed photophysics.

Dynamic Covalent Chemistry

“…In an attempt to substantiate this hypothesis, an exchange experiment was performed where a diolefin‐[2]catenane 126 incorporating benzene diimide groups as part of the π‐electron‐poor circuit was exposed to 124 in the presence of the Grubbs' catalyst 4 (Scheme ). The formation of the thermodynamically more stable [2]catenane 125 was anticipated from the stronger interaction observed between naphthalene bis(carboximides) with 1/5DN38C10 than that involving benzene bis(carboximides) 137a. Although this product was indeed observed to form, protracted reaction times were necessary, and the slow reaction kinetics ultimately prevented the system from reaching equilibrium.…”

Local dipole interactions induce helicity of (S)-2-butyl-N-(1,8-naphthaloyl)-2-aminobenzoate molecules containing 1,8-naphthalimide rings utilized as a column building blocks: X-ray and quantum mechanical studies

“…Aromatic amides such as 1,2,4,5-benzenetetracarboxydiimides (pyrromellitic diimides) and 1,4,5,8-naphthalenetetracarboxydiimides (NDI) are neutral, planar, electron deficient molecules whose synthetic potential has been used in construction of oligomeric molecules [1][2][3], new fluorophors [4], and catenanes [5], and whose structural and electronic properties have been utilized in many different areas, to mention medicinal chemistry [6] and photophysics [7]. Monoimides, like phtalimides and 1,8-naphtalimides, have been used successfully in crystal engineering [8] and as chromophores in stereochemical studies [9][10][11].…”

Generation of a Dynamic System of Three‐Dimensional Tetrahedral Polycatenanes

“…The exchange between free and bound crown ether was observed to be slow on the NMR timescale at 298 K as peaks for the catanated complexes appeared as new resonances and did not shift with changes in crown ether concentration. The 1 H resonances of bound crown ether molecules (Figure 1 c, peaks H a′ , H b′ , and H c′ ) appeared upfield of resonances attributed to free crown ether (peaks H a , H b , and H c ) owing to the close proximity of the shielding aromatic NDI 15. We attribute the broadening of the 1 H resonances of cage A in the DCL to loss of symmetry, with the exception of the new NDI peak (peak H 10′ in Figure 1 c).…”