Flexible self-assembling porphyrin supramolecules

1. Flexible self-assembling porphyrin supramolecules Ken D. Johnstone,Kentaro Yamaguchiand Maxwell J. Gunter O r g . B i o m o l . C h e m . , 2 0 0 5 , 3 , 3 0 0 8 . 3 0 1 7 Tobe Laboratory Hirokazu TAKANO

2. Introduction Extensively explored as useable molecular scale machines for electric device Rotaxane Catenane Rotaxane Catenane There is no covalent bond in these multi-component. They utilise subtle secondary interactions to drive their switching motion. The study of these systems has led to the invention of a variety of more complex, hybrid topologies.

3. Introduction Hydrogen bonding p – p interaction Charge transfer interaction Coordination between pyridyl ligands and metallated porphyrin All assembly process is reversible The system has a possibility to improve the efficiency and outcome.

4. Introduction DOSY NMR (diffusion ordered spectroscopy NMR) It is possible to separate the NMR signals of different species according to their diffusion coefficient in the mixture. CSI-MS (cold-spray ionization mass spectrometry) a variant of electrospray ionization (ESI) MS Ionisation under very mild condition by using of higher dielectric constants to afford low temperature ionization by solvation It is possible to charactarise thermally unstable compounds such as labile organometallics

5. Synthesis of Compound 5 (iv) HOBT, EDC, NEt3, DCM, rt, 43 %

6. 1H-NMR Comparison at 30 °C of 9, 11, 5 aromatic shielding effects resulting from a crown–diimide interaction. but because of fast exchanging process observed spectra at 30 °C is time-averaged shift of complexed and umcomplexed species VT-NMR experiment is useful in studying dynamic behavior.

7. 1H-NMR Temperature Comparison for 5 more up field shift for Ha-d and Hi-q at lower temperature complexed species becomes predominant at lower temperature

8. Conformation of 5 Upfield shifts of all aromatic protones in the crown and diimido aromatic protones An offset face-to-face alignment crown -diimido interaction Because of the flexible nature of the ethylene glycol subunits, intramolecular complexed species is predominantly. ・A dramatic upfield shift for Hk An edge-to-face alignment of the benzo crown relative to the diimide aromatic ・NOESY experiment at 30 °C Correlations between the diimide protones (Ha-d) and both H18and H24 on the crown ・UV absorption at 484 nm Charge transfer band of the crown-diimide complexation

9. CSI-MS for mixture of 5 and 3 5 + CDCl3 3 With a slight amount of dimer Low temperature NMR experiment Distinguishable for the bound and unbound species only below –30 °C Inherently fast intramolecular exchange process for 5

10. Synthesis of Compound 6 HOBT, EDC, NEt3, DCM, for 3 days + 51% Ru3(CO)12, toluene, reflux, for 2 days 52 % 16 6

11. 1H-NMR Comparison at 30 °C of 16, 11 ・ An upfield shift for Ha-d and H7, 8, 9, 10 11 ・ A downfield shift for H16 The diimide and neighboring protons lie above the porphyrin subunit. 16

12. 1H-NMR Comparison at 30 °C of 6, 16 ・ A greatly upfield shift for He-g ・ An upfield shift for H1 Either an intra- or inter-molecular ruthenium-pyridyl coordination ・ A downfield shift for Ha-d 6

13. Conformation of 16 and 6 Because of the flexible nature of the ethylene glycol subunits, intramolecular complexed species is predominantly. Face-to-Face porphyrin-diimide intramolecular interaction The pyridyl-ruthenium coordination and the carbonyl ligand prevent any porphyrin - diimide interaction from occurring.

14. COSY NMR at 30 °C for mixture of 6 and 1 + Upfield shifts are apparent for the terminal pyridine (He-h), diimide (Ha-d), porphyrin (Hi-t,b) protone in 6 and the naphthalene crown (Hu-w) in 1 exchange process between unbound and bound species is slow due to the intramolecular porphyrin coodination clipping effect COSY NMR of 6 and 1 mixed in CDCl3 at 30 °C. Presence of both unbound and bound crown and diimide protones

15. DOSY NMR for mixture of 6 and 1 DOSY NMR experiment (left) performed on the mixture of 6 and 1 in CDCl3 at 30 °C (0.01 M). The presence of components 8 (above) and 1 (below) are evident. Their corresponding 1D proton NMR slices are shown on the right. Only two differently sized species Presumably [2] catenane 8 and crown 1 It would be impossible to identify 6 with mixture, because 6 have a similar molecular size to 8, with overlapping chemical shifts

16. CSI-MS for mixture of 6 and 1 6 + CDCl3 With a slight amount of dimer from CSI-MS 6 adopts an intramolucular porphyrin – pyridine coordination co-conformation.

17. Conclusion A series of self-assembling rotaxane component hybrid systems with varying complexity have been successfully constructed and analyzed, using NMR and CSI-MS techniques. Modification of both 5 and 6, by both incorporation of shorteror more rigidlinker subunits and the use of stronger binding components, could afford supramolecular mixtures with a larger percentage of higher-order co-conformers. The simple, reversible assembly process associated with such supramolecular systems allow quite large, complex, multi-functional targets to be formed simply by mixing suitably designed components.