7-Amino-dibenzofuran-3-carboxylate: A new probe for femtosecond dynamic microsolvation studies of biomolecules

The reorientational dynamics of a polar environment, for example water in the hydration shell of biomolecules, can be measured with a molecular probe by time-resolving its fluorescence Stokes shift. The new probe 7-amino-dibenzofuran-3-carboxylate (ADC) was designed and synthesized for such use in double-stranded DNA where it may replace a base pair. This contribution concentrates on the synthesis, including the DNA bulding block, and on the radiative properties of the chromophore independent of the biomolecule. The X-ray diffraction structure and radiative properties are compared to ab-initio quantum-computational predictions. After ππ* excitation near 330 nm in acetonitrile, the dynamic Stokes shift is followed by femtosecond transient absorption around 445 nm, at the red half-point of a strong excited-state-absorption band. Polar solvation dynamics is reported faithfully by this chromophore.