Dipole moments of indoles in their ground and the first excited singlet states

Indole as a new sustainable aromatic unit for high quality biopolyesters

“…S21 †) revealed that these indole-based polyester films were generally more hydrophilic (θ = 45-62°) than the films made from PET, PETG, and Akestra (θ = 64-75°) under the same film-casting and measurement conditions. This observation was consistent with the higher polarity of indole (dipole moment 2.13 D), 46 compared with that of benzene rings (dipole moment ∼0) contained in PET, PETG and Akestra.…”

Synthesis, Enzymatic Degradation, and Polymer-Miscibility Evaluation of Nonionic Antimicrobial Hyperbranched Polyesters with Indole or Isatin Functionalities

“… 59 , 73 , 74 Furthermore, BISA showed a higher T g than BIN, which could be due to the stronger dipole interactions of BISA (dipole moment of ∼5.65 D for isatin and ∼2.07–2.38 D for indole groups). 75 , 76 Furthermore, the second heating curve of BH40 displayed a broad exotherm at ∼70 °C and a broad endotherm at ∼115 °C, which could be attributed to the formation and cleavage of hydrogen bonds by the OH groups in BH40. 77 These exo- and endothermic events were not observed for BISA and BIN, which indicated that the remaining OH groups (∼20%) did not form significant hydrogen bonds.…”

“…According to the DSC results (Figure ), the glass transition temperatures ( T g ) of BISA and BIN are 90 and 64 °C, respectively, which are significantly higher than that of BH40 ( T g ≈ 28 °C). This can be attributed to the incorporation of cyclic aryl groups (indole or isatin), which can increase the overall structural rigidity (and T g ) of linear and dendritic polymers. ,, Furthermore, BISA showed a higher T g than BIN, which could be due to the stronger dipole interactions of BISA (dipole moment of ∼5.65 D for isatin and ∼2.07–2.38 D for indole groups). , Furthermore, the second heating curve of BH40 displayed a broad exotherm at ∼70 °C and a broad endotherm at ∼115 °C, which could be attributed to the formation and cleavage of hydrogen bonds by the OH groups in BH40 . These exo- and endothermic events were not observed for BISA and BIN, which indicated that the remaining OH groups (∼20%) did not form significant hydrogen bonds.…”

On the Estimation of Excited-State Dipole Moments from Solvatochromic Shifts of Absorption and Fluorescence Spectra

“…(4) and (5). This led to the fact that some later authors [24][25][26][27][28] regard expressions (15) and (16) together with (25) and (26) as derived originally in [23]. Generally, when dipole moments m m e and m m g are not parallel to each other but form an angle j, the use of (18) and (19) leads to [8,32] (34) (35) Assuming that the symmetry of the investigated solute molecule remains unchanged upon electronic transition, and the ground and excited state dipole moments are parallel, based on (18) and (19) one obtains (36) (37) or by dividing (37) by (36): (38) The parameters m 1 and m 2 occurring in (15) and (16) for the difference ñ A -ñ F and the sum ñ A + ñ F of the wavenumbers, which are linear functions of the solvent polarity parameters f (e, n) and j (e, n), can be determined from the slopes of the straight lines.…”

“…By neglecting the second term in (28) we receive (25). The parameters m 1 and m 2 in [8,11], (18) and (19), and Bakhshiev's [9,29] parameters Dc a-f and C 2 fulfill the relations…”