Solvent-Controlled Photoswitching of Azobenzene: An Excited State Shuttle.

The light-controlled excited state trans-cis isomerization process is a key to the development of conversion of light energy to mechanical motion at the molecular level. Considerable efforts have been made in tuning the isomerization process with electron donor and acceptor substituents by altering the excited state reaction coordinate. Here, we report a two novel push-pull series of para-diethylamino (DEA) and diphenylamino (DPA) substituted (E)-4'-((4-(diethylamino)phenyl)diazenyl)-N,N-diphenyl-[1,1'-biphenyl]-4-amine (1) and (E)-4'-((4-(diphenylamino)phenyl)diazenyl)-N,N-diphenyl-[1,1'-biphenyl]-4-amine (2).

Direct evidence of solvent polarity governing the intramolecular charge and energy transfer: ultrafast relaxation dynamics of push-pull fluorene derivatives.

Photoinduced charge and energy transfer are significant photophysical processes controlling the efficiency of photosynthesis and molecular electronics. Here, the influence of solvent polarity and excitation wavelength on the dynamics of excited state relaxation pathways of a push-pull chromophore (PXFCN), where phenoxazine and cyano fluorene acted as a donor and an acceptor, respectively, is investigated in detail by using steady state spectroscopy, nanosecond and femtosecond transient absorption spectroscopy and picosecond emission spectroscopy. In acetonitrile (ACN), the steady state emission spectra of PXFCN exhibited three maxima at around 330, 405 and 620 nm covering the complete continuum range (CIE coordinates of 0.