Solvatochromic correlations and ground- and excited-state dipole moments of curcuminoid dyes

Curcumin-benzodioxaborole chelates

“…The band around 270 nm is characteristic for benzenoid rings. Curcumin itself exhibits absorption maxima at 265, 422, and 436 nm (shoulder); 36 the first band at 265 nm corresponds to a π→π* transition, whereas the band at 422 nm can be due either to an n→π* transition as proposed by Balasubramanian,42,43 or to a combination of π→π* and n→π* transitions, according to our calculations. Free catechol has two absorption bands at 210 and 275 nm, both being π→π* transitions.…”

“…Table 2 presents the dipole moments determined as described previously. 37 One should note that previously determined dipole moments were 3.32 D for curcumin, 36 3.12 D for dicinnamoylmethane (the parent compound of curcumin without hydroxy and methoxy groups), 36 The relatively large dipole moments of the compounds under study are very similar. This is not surprising because the alkyl groups that constitute the difference between all compounds exert only a small effect on the overall dipole moment of the boron chelates.…”

“…The absorption maxima are shown in Table 3. Electronic absorption spectra of curcuminoids were discussed in a previous publication by Párkányi et al, 36 and also by Arrieta 33 and Chignell et al 41 The longest-wavelength band due to the chelate as a whole does not differ appreciably between all compounds, and is situated around 510 nm. The intermediate band around 420 nm appears as a shoulder for 10a and 10b, and is split into two bands for 10c, 10d; this band corresponds to the curcumin moiety, as seen below.…”

Solvatochromic Stokes shift and determination of excited state dipole moments of free base and zinc octaethylporphyrin

“…Several theoretical and experimental studies on ground and excited state dipole moments by using different techniques have been widely extended to a variety of organic fluorescent compounds like curcuminoid [49], hemicyanine [50], hydroxycoumarin [51], coumarin [52], purine [53], exalite [54], fluorescein [55], flavone [56], acridienedione [57], acridine and phenazine [58], quinazoline [59], substituted anthraquinone [60] and some laser dyes [61]. Generally, the most used method for determination of excited state dipole moment of a molecule is based on solvatochromic one.…”

Ultra-High to Ultra-Low Drug Loaded Micelles: Probing Host-Guest Interactions by Fluorescence Spectroscopy

“…CUR is highly solvatochromic, i.e. its absorption and emission properties strongly depend on its microenvironment [31] causing Stokes shifts between 2000 and 6000 cm -1 in organic media (Figure 1). [32] While in aprotic solvents, CUR lacks any specific interactions, hydrogen-bonding is present in protic solvents.…”