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Abstract We describe a templating/covalent capture strategy that enables photochemical formation of 8 cyclobutanes in one noncovalent assembly. This process was characterized by experiment and quantum mechanical/molecular mechanics (ONIOM) calculations. Thus, KI and 16 units of 5′‐cinnamate guanosine form a G‐quadruplex where C=C π bonds in neighboring G4‐quartets are separated by 3.3 Å, enabling [2+2] photocycloaddition in solution. This reaction is high‐yielding (>90 %), regio‐ and diastereoselective. Since all components are in dynamic equilibrium this photocycloaddition is catalytic in K+.
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Reversed Cation Selectivity of G 8 ‐Octamer and G 16 ‐Hexadecamer towards Monovalent and Divalent Cations
Abstract A reverse‐binding‐selectivity between monovalent and divalent cations was observed for two different self‐assembly G16‐hexadecamer and G8‐octamer systems. The dissociation constant between G4‐quadruplex and monomer was calculated via VT‐1H NMR experiments. Quantitative energy profiles revealed entropy as the key factor for the weaker binding toward Ba2+compared with K+in the G8‐octamer system despite stronger ion‐dipole interactions. This study is the first direct comparison of the G4‐quartet binding affinity between mono and divalent cations and will benefit future applications of G‐quadruplex‐related research. Further competition experiments between the G8‐octamer and 18‐crown‐6 with K+demonstrated the potential of this G8system as a new potassium receptor.
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- Award ID(s):
- 1665122
- PAR ID:
- 10138486
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Chemistry – An Asian Journal
- Volume:
- 15
- Issue:
- 7
- ISSN:
- 1861-4728
- Format(s):
- Medium: X Size: p. 1030-1034
- Size(s):
- p. 1030-1034
- Sponsoring Org:
- National Science Foundation
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