Slow proton transfer dynamics of a four member intramolecular hydrogen bonded isoindole fused imidazole system: A spectroscopic approach to photophysical properties

Modulation of Excited State Proton Transfer Dynamics of a Lactim–Lactam Tautomeric System in Different Block Copolymer–Surfactant Aggregates

“…15 Photophysical studies of ADCL in various organic aprotic solvents suggest that the PT process occurring in the molecule is of intramolecular one. 15 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 10 the three studied surfactant environments compared to the bulk aqueous phase. The locations of ADCL in the SDS (3.48 mM), CTAB (3.48 mM) and TX 100 (3.48 and 15.66 mM) micellar environments have been discussed later.…”

“…From our previous study 15 Figure 8 shows the time resolved fluorescence decay of ADCL at the PT band in the pure 1% w/v P123 medium and in the P123-surfactants aggregates and the corresponding results are presented in Table 5. It is readily found that 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 18 in 1% w/v P123 medium we got a much slower rise time of ~ 334 ps.…”

“…whether the PT process occur through any guest molecule like protic solvents etc or it occurs within a bare molecule through an intramolecular proton transfer (IPT) process 11-14 . Our presently studied molecule ADCL also contain a four member intramolecular hydrogen bonding network and it exhibits dual emissions in various solvents due to the operation of PT process and the higher energy band is assigned to the lactim emisson (or, local emission or LE) and the lower energy band is due to the lactam emission (or, proton 4 transfer emission, PT band) 15 . It is also found that the PT rate becomes faster in hydrophilic solvents and in water it is too fast that we cannot account that 15 . Therefore, it is quite expected in different supramolecular assemblies the PT rate of ADCL could be interestingly modified as the microenvironment of the supramolecular assemblies are very much different from that of the bulk homogeneous medium.…”

“…In the three different surfactant media the lactam emission band intensities are found to be increased with a blue shift in the emission maxima compared to the bulk water (501 nm in 3.48 mM CTAB, 511 nm in 3.48 mM SDS and 498 nm in 15.66 mM TX 100 medium, Figure 2)whereas the lactim emission intensity also increases (but not that extent as lactam emission) but no shift in the lactim emission maximum is observed (the figures are not shown in the text). From our earlier study of ADCL15 it was observed that the lactim emission maxima are practically insensitive to the nature of solvents whereas the lactam emission maxima are found to be changed in solvents of different polarity or hydrophilicity. Therefore the hypsochromic shift of the PT band observed in the various surfactants media indicate that the molecule must experience a less polar environment in…”

Theoretical insights into excited-state hydrogen bonding effects and intramolecular proton transfer (ESIPT) mechanism for BTS system

“…9-18 . By the light of nature, both applied and cognitive attention have been paid to ESIPT phenomenon, which becomes a demanding subject of research [19][20][21][22][23][24][25] .Generally, ESIPT means the transfer of a hydroxyl (or amino) proton to an oxygen (or nitrogen) acceptor via pre-existing hydrogen bonds. Upon photoexcitation, an unstable position of proton is resulted from the projection of the nuclear wave function of molecule on the excited-state potential energy surface (PES) [26][27][28][29][30][31][32][33][34][35] .…”