Quantum Yield Switching of Fluorescence by Selectively Bridging Single and Double Bonds in Chalcones:  Involvement of Two Different Types of Conical Intersections

Abstract

From the fluorescence properties of chalcones as a function of solvent polarity, and by the comparison to derivatives with donors and acceptors and with various selectively bridged bonds, it can be concluded that two emissive and two nonemissive states are needed to describe the fluorescence behavior. Three of these states are connected with bond twisting and lead to species with high or low dipole moment, two of them situated in the proximity of a conical intersection.

Crystal Structures of Two Macrocyclic Bischalcones Possessing 26-Membered Rings

“…The aliphatic chains O1-C7-C8-C9-O2 and O4-C25-C26-C27-C28-C29-O5 in 1 and O1-C7-C8-C9-C10-O2 and O4-C26-C27-C28-C29-O5 in 2 are mostly in staggered arrangement with the dihedral angles ranging from 57 to 64 ∘ . Antiarrangements were observed for C25-C26-C27-C28 and C26-C27-C28-C29 in 1 and C7-C8-C9-C10 in 2 (dihedral angles 177.32 (17), 176.19 (17), and 175.10 (9) ∘ , resp.). It is interesting to note that the arrangements for the apparently similar units C7-C8-C9-C10 and C26-C27-C28-C29 in 2 are somewhat different in the crystalline state.…”

“…Moreover, these compounds can be transformed in a number of ways into other biologically active heterocycles, for example, pyrimidines [9], isoxazole and pyrazole [10], and pyridines [11]. Macrocycles incorporating more than one chalcone moiety have great potential in generating new compounds suitable for molecular recognition [12][13][14][15] and photophysical [16,17] studies. Recently, we reported the synthesis of a new family of 22-to 28-membered macrocycles containing two chalcone moieties.…”

“…The interesting aspects of that study arising out of the folded nature of the molecule encouraged us to record the X-ray crystallographic data of some other compounds of the family. In this paper, we report the X-ray crystallographic data of two other compounds, (2E,25E 2,5,7,9,17,19,21,24,26,28,30,38,40-tetradecaene-4,23-dione (2) (Scheme 1) was completed using the Claisen-Schmidt reaction in highly diluted aqueous methanol solution. The methods for the synthesis of 1 and 2 and their spectral data have been presented in our previous paper [18].…”

Simple synthesis of a new family of 22- to 28-membered macrocycles containing two chalcone moieties

“…[1][2][3][4][5][6][7] Moreover, these compounds are known to be transformed into other compounds in a number of ways, many of which are biologically active heterocycles. [8][9][10][11] Macrocycles incorporating more than one chalcone moiety have great potential in generating new compounds suitable for molecular recognition [12][13][14][15] and photophysical 16,17 studies. The chemical literature shows sporadic reports of construction of a few such types of compounds.…”

Towards simple and efficient molecular reporters: combining electron transfer and charge transfer in functional dyes of donor–acceptor–spacer–donor constitution

“…0.21 g (1.5 mmol) phenylhydrazine hydrochloride and the corresponding chalcone [21][22][23] (1 mmol) were heated for 3h at 100 °C in a solution of 5 mL absolute ethanol and 0.5 ml acetic acid. The resulting reaction mixture was poured into 50 mL ice water and neutralized with 10% aqueous sodium carbonate.…”