Very short lifetimes (a few picoseconds) of the lowest excited singlet (S1) state of benzophenone (BP) and p-hydroxybenzophenone (HOBP) suggest that they have π* character in all kinds of solvents. However, in the case of the p-amino-substituted benzophenones (ABPs), the nature of the S1 state, whether it is n–π* or π–π*, depends on the nature of the solvent and the identity of the substituent groups. The lowest excited triplet (T1) state of BP has nπ* character in all kinds of solvents and hence phosphorescence decay is short (a few ms). The T1 state character of HOBP and ABP’s are solvent dependent. In a few cases dual exponential decay of phosphorescence indicates that n–π* and π–π* triplet states lie close to each other. The π–π* type of T1 state has longer phosphorescence lifetime (a few tens of ms). Investigations of the ultrafast relaxation dynamics of 4-N,N-dimethylaminobenzophenoene (DMABP) in different kinds of solvents of varying polarities and viscosities reveal that conversion of the locally excited (LE) state to the twisted intramolecular charge transfer (TICT) state by twisting of the dimethylanilino group is the major process, which is responsible for the efficient non-radiative relaxation mechanism of the S1 state of this molecule and solvation dynamics plays a minor role in it. In self-quenching interaction between the triplet state and its ground state, the n–π* kind of T1 state plays the major role and no triplet exciplex is involved as an intermediate. The T1 state of BP is equally reactive towards hydrogen atom abstraction reaction with the ground state of each of the ABPs either by direct hydrogen atom transfer or by a chargetransfer-coupled proton-transfer mechanism. Exciplex formation has been observed only in the case of the reaction between the T1 state of BP and DMABP.
Research on Chemical Intermediates – Springer Journals
Published: Jan 1, 2005
It’s your single place to instantly
discover and read the research
that matters to you.
Enjoy affordable access to
over 18 million articles from more than
15,000 peer-reviewed journals.
All for just $49/month
Query the DeepDyve database, plus search all of PubMed and Google Scholar seamlessly
Save any article or search result from DeepDyve, PubMed, and Google Scholar... all in one place.
Get unlimited, online access to over 18 million full-text articles from more than 15,000 scientific journals.
Read from thousands of the leading scholarly journals from SpringerNature, Elsevier, Wiley-Blackwell, Oxford University Press and more.
All the latest content is available, no embargo periods.
“Hi guys, I cannot tell you how much I love this resource. Incredible. I really believe you've hit the nail on the head with this site in regards to solving the research-purchase issue.”Daniel C.
“Whoa! It’s like Spotify but for academic articles.”@Phil_Robichaud
“I must say, @deepdyve is a fabulous solution to the independent researcher's problem of #access to #information.”@deepthiw
“My last article couldn't be possible without the platform @deepdyve that makes journal papers cheaper.”@JoseServera