Reaction and deactivation of excited acridine in ethanol

Abstract

Electronic deactivation processes of excited acridine have been investigated in ethanol where photoreduction occurs under UV irradiation. The fluorescence lifetime and yield increase with decreasing temperature, whereas the yield 8 of the lowest triplet state , ( , *), the yield of acridine semiquinone C radical R, and the yield of photoreduction through the molecular mechanism decrease. Temperature-dependent intersystem crossing occurs through the Si(tt,tt*) +± (+AE4) S2(n,Tr*) -» 3( ,7 *) -* ^ , *) and the 8, ( , *) -(+ £3) 3( , *) -1( , *) transition. R is mainly produced from 2( , *) and slightly from 2( , *) and/or 81( , •*). The photoreduction through the molecular mechanism occurs only in 82( , *). Temperature-independent intersystem crossing, i.e., the S[ ( , *) -2( , *) ^ , *) transition, is negligible above 170 K, suggesting rapid deactivation of 2( , *) on account of the R formation reaction.

A combined theoretical and experimental study on molecular photonics

“…The fluorescence quantum yield φ fl = 0.03. For methanol solution, φ fl = 0.03 [38]. In nonpolar solvents, fluorescence has not been detected.…”

“…This will extend the sensory abilities of the compounds. Acridine has been much investigated since the mid-twentieth century and many of its properties have been the subject of a number of monographs [12,37] and more recent original papers [see, e.g., [38][39][40][41][42][43][44]). We have included acridine in the list of compounds discussed here with the goal of analyzing the changes in their spectral-luminescent properties and photophysical processes depending on the nature of the substituent in position 9 of acridine.…”

Excited state relaxation of 9-(4-diethylaminostyryl)-acridine

“…Triplet state formation [11][12][13], excited state reduction [14,15], and relaxation between excited ππ * and nπ * states [11,[16][17][18] were reported for different acridine derivatives. The triplet state formation in some of acridines takes place very efficiently, however, it has already been reported [10] that there is no evidence of triplet state population of DSA dyes.…”

“…It was suggested in [14,15] that the excited state relaxation of acridine occurs through its photoreduction, taking place in the nπ * state. A similar pro-cess, excited state electron transfer between acridines and different solvents or DNA, was also widely discussed [19].…”

Carbon Nanotube–Acridine Nanohybrids: Spectroscopic Characterization of Photoinduced Electron Transfer

“…This hydrogen bonding and/or the increase of polarity, is at the origin of the drastic changes in fluorescence quantum yield and lifetime of acridine derivatives. [33][34][35][36][37][38] The lowest singlet excited state is now supposed to be a 1 A C H T U N G T R E N N U N G (p,p*) state. However, in non-polar solvents, the 1 A C H T U N G T R E N N U N G (n,p*) state is coupled with the latter and leads to an increase of non-radiative processes like intersystem crossing.…”