Structure and Physical Properties of Cardamonin: A Spectroscopic and Computational Approach

Abstract

This is the first study of the crystal structure of cardamonin (CA) confirmed using single-crystal XRD analysis. In the crystal lattice of CA, two symmetry independent molecules are linked by hydrogen bonds within the layers and by the π···π stacking interactions in the columns which lead to the occurrence of two types of conformations among the CA molecules in the crystal structure. To better understand the stability of these arrangements in both crystals and the gaseous phase, seven different CA dimers were theoretically calculated. The molecular structures were optimized using density functional theory (DFT) at the B3LYP/6–311G+(d,p) level and the spectroscopic results were compared. It was found that the calculated configurations of dimer I and III were almost identical to the ones found in the CA crystal lattice. The calculated UV-Vis spectra for the CA monomer and dimer I were perfectly consistent with the experimental spectroscopic data. Furthermore, enhanced emissions induced by aggregated CA molecules were registered in the aqueous solution with the increase of water fractions. The obtained results will help to further understand the relation between a variety of conformations and the biological properties of CA, and the results are also promising in terms of the applicability of CA as a bioimaging probe to monitor biological processes.

Naturally Occurring Chalcones with Aggregation-Induced Emission Enhancement Characteristics

“…The differences in the spectra in aqueous solutions, methanol, ethylene glycol and chloroform were probably caused by both solvent (solvatochromism) and aggregation effects [17]. Our previous paper on cardamonin showed the similarity between the absorption maxima of CA in the aqueous solution and the crystalline state, where two dimeric forms were observed [27]. Moreover, only for licochalcone A, a near mirror image was observed between the absorption and fluorescence emission spectra (Figure 2) in the studied solvents.…”

“…Researchers' attention has been attracted to chalcones as AIE properties have been reported for several of them [9,[23][24][25]. Chalcones are a class of compounds with a characteristic scaffold consisting of two substituted aromatic rings connected by the carbonyl group and the α,β-unsaturated system (aromatic ketone and enone), giving them unique chemical and biological properties [26,27]. Naturally occurring chalcones are a subclass of the compounds belonging to the flavonoid family, and they are found in many edible plants, fruits and vegetables [28,29] that exhibit a wide range of bioactivity, including antioxidant, anti-inflammatory, antimicrobial and anticancer properties [30,31].…”

“…In light of these facts, the initiation of research that will result in finding a potential use for the AIE/AIEE-active natural chalcones seems to be appropriate. The structural and spectroscopic properties of natural chalcones are of continual interest to our team [26,27,[38][39][40]. Our attempt consists of evidence that the CA molecules in the aqueous solution exist in the dimeric state, whereas in the ethanol solution, they exist mainly as monomers.…”

“…Our attempt consists of evidence that the CA molecules in the aqueous solution exist in the dimeric state, whereas in the ethanol solution, they exist mainly as monomers. Moreover, with the increase in water fraction, the CA molecule shows enhanced emissions induced by the aggregation (AIEE) effect [27].…”

Triggering the Amphotericin B Pore-Forming Activity by Phytochemicals

“…Thus, we concluded that the enhancement in AmB-produced transmembrane current by phloretin, biochanin A, and genistein was not related to the increase in the membrane concentration of polyene. The intersection of the absorption spectra of the antibiotic and the phytocompounds, which reduce the AmB pore-forming activity, cardamonin, 4′-hydroxychalcone, licochalcone A, butein, curcumin, and piperine [ 40 , 41 , 42 , 43 , 44 , 45 ], does not allow one to estimate the antibiotic concentration in the membrane in the presence of these compounds by the spectrophotometric method.…”