Intramolecular proton transfer in the first-excited electronic states of 4-methyl-2,6-diformyl phenol in some hydrocarbon solvents

✍ Scribed by S. Mitra; R. Das; S. Mukherjee

• Publisher: Elsevier Science
• Year: 1993
• Tongue: English
• Weight: 526 KB
• Volume: 202
• Category: Article
• ISSN: 0009-2614
• DOI: 10.1016/0009-2614(93)90046-4

✦ Synopsis

Proton translocation in the singlet excited state of 4-methyl-2,6-diformyl phenol (MFOH) results in an interesting fluorescence band at 535 nm. The fluorescence emission and excitation spectra of MFOH are recorded and a time-correlated single-photon counting technique is used to determine the fluorescence lifetimes in some hydrocarbon solvents at room temperature. The stable molecular structure in the ground state of MFOH is an intramolecularly hydrogen bonded closed conformer from which proton transfer takes place in the first excited '(nr*) state. The Stokes-shifted fluorescence band observed in the yellow-green region is likely to originate from the enol tautomer which is found to exist even at 77 K. From nanosecond measurements and the quantum yields of fluorescence we have determined proton transfer rates. It is suggested that the proton transfer in MFOH is relatively slow in these solvents and MFOH can have only one ground state conformation, except in benzene and toluene.