Crystal structure of 3,13-dimethoxy-5,6,10,11-tetrahydrofuro[3,4-i][5]helicene-7,9-dione

Columnar Organization of Carbo[5]helicene Directed by Peripheral Steric Perturbation

Three carbo[5]helicenes ([5]CHs) containing benzylmaleimide groups displayed columnar stacked organizations, including dislocated, parallel, and alternating (P)- and (M)-helix molecular arrangements in the solid state. The peripheral benzyl groups resulted in very small steric interactions that are responsible for the formation of columnar stacked arrangements in the crystalline state.

Dual-Analyte Fluorescent Sensor Based on [5]Helicene Derivative with Super Large Stokes Shift for the Selective Determinations of Cu2+ or Zn2+ in Buffer Solutions and Its Application in a Living Cell

A new fluorescent sensor, M201-DPA, based on [5]helicene derivative was utilized as dual-analyte sensor for determination of Cu²⁺ or Zn²⁺ in different media and different emission wavelengths. The sensor could provide selective and bifunctional determination of Cu²⁺ in HEPES buffer containing Triton-X100 and Zn²⁺ in Tris buffer/methanol without interference from each other and other ions. In HEPES buffer, M201-DPA demonstrated the selective ON-OFF fluorescence quenching at 524 nm toward Cu²⁺. On the other hand, in Tris buffer/methanol, M201-DPA showed the selective OFF-ON fluorescence enhancement upon the addition of Zn²⁺, which was specified by the hypsochromic shift at 448 nm. Additionally, M201-DPA showed extremely large Stokes shifts up to ∼150 nm. By controlling the concentration of Zn²⁺ and Cu²⁺ in a living cell, the imaging of a HepG2 cellular system was performed, in which the fluorescence of M201-DPA in the blue channel was decreased upon addition of Cu²⁺ and was enhanced in UV channel upon addition of Zn²⁺. The detection limits of M201-DPA for Cu²⁺ and Zn²⁺ in buffer solutions were 5.6 and 3.8 ppb, respectively. Importantly, the Cu²⁺ and Zn²⁺ detection limits of the developed sensors were significantly lower than permitted Cu²⁺ and Zn²⁺ concentrations in drinking water as established by the U.S. EPA and WHO.

Novel Cu2+-specific “Turn-ON” fluorescent probe based on [5]helicene with very large Stokes shift and its potential application in living cells

The sensor provides Cu²⁺-sensitive with low detection limit and very large Stokes shift, and can induce the emission in the HepG2 cellular system.