Thermal-Induced Twisting and Photoinduced Planarization of Salicylideneaniline in Alcohols.

Thermofluorochromism and photochromism of salicylideneaniline (SA) in alcohol were investigated using steady-state and time-resolved fluorescence and absorption spectroscopy. The planar -enol form of SA in alcohols is converted into the twisted -enol form on heating. This conversion results change in the emission maximum from the 530 to the 440 nm region with an increase in fluorescence intensity, which confirms the absence of intramolecular hydrogen bonding between imine nitrogen and phenolic hydrogen in the twisted -enol form.

Excitation-resolved area-normalized emission spectroscopy: a rapid and simple steady-state technique for the analysis of heterogeneous fluorescence.

Excitation-resolved area-normalized emission spectroscopy (ERANES) is proposed as a new steady-state fluorescence technique for the investigation of heterogeneous fluorescence (HGF) from a mixture of fluorophores and fluorophores present in various environments and proteins. The presence of a single isoemissive point was used to confirm the presence of two absorbing and emitting species in the system. The isoemissive point was found to occur at the wavelength where the ratio of wavelength dependent fluorescence quantum yield of the emissive species equals to the ratio of their total fluorescence quantum yield.