Studies on fluorescent species of spiro-indolinonaphthooxazines and their fluorescence spectra

Photophysical behavior of spiro[1,3,3-trimethylindolino-2,3'-naphtho[2, 1-b ]-1,4-oxazine] (SP1) and spiro[1,3,3,2'-tetramethylindolino-2,3'-naphtho[2, 1-b]-1,4-oxazine] (SP2) were studied. The fluorescent species and their sp ectra of SP1 and SP2 in polar solvents (acetonitrile and methanol) and non- polar solvent (cyclohexane) were investigated. The fluorescence decay in po lar solvents was studied by picosecond time-correlated single photon counti ng. In most cases, fluorescence decay obeyed triexponential decay kinetics. The major fluorescent species is an excited intermediate which has similar conformation as its precursor ((SP)-S-1*) formed after the bond cleavage b etween spirocarbon and oxygen in oxazine ring. The effects of molecular str ucture and solvent polarity on fluorescence spectra and fluorescence decay lifetime were studied.