Search Results (3)

Natural curcumin is composed of three curcuminoids, namely curcumin (CUR), deme-thoxycurcumin (DMC) and bis-demethoxycurcumin (BDMC). These compounds are utilized in various biophotonics applications, including photodynamic therapy (PDT). This work aimed to evaluate the photodynamic action (alternative to antibiotics) of synthetic curcuminoids against Staphylococcus aureus. Herein, we evaluated an optimal proportion of the three curcuminoids mixed in solution to improve photoinactivation effects. Therefore, a set of computational calculations was carried out to understand the photodynamic action (stability and mechanism) of curcuminoids. Regarding computational analysis, the curcuminoid molecules were optimized using DFT with the hybrid exchange–correlation functional M06-2X, which includes long-range correction, and the 6-311++G(d,p) basis set. DMC and BDMC were more effective as photosensitizers than curcumin at a very low concentration of 0.75 µM, inactivating more than five orders of magnitude of S. aureus. Theoretical UV-vis absorption spectra showed that at maximum absorption wavelengths, electronic transitions of the π→π* type originated from H→L excitations. The BDMC was more stable than the other two curcuminoids after photobleaching, and the fluorescence emission was also higher, which could lead to its usage as a fluorescence dye to track bacteria. In fact, the results of electronic structure calculations proved that the stability order of curcuminoids is CUR < DMC < BDMC. The mixture of synthetic curcuminoids was more effective in the inactivation of S. aureus compared to curcumin by itself; for all proposed mixtures, an equal or superior reduction was achieved. Full article

A series of D-π-A type dyes were designed based on the experimentally synthesized A1 by introducing different functional groups on the donor and π-spacer, and the optical and electrical properties were calculated by using density functional theory (DFT) and time-dependent DFT (TD-DFT). P1–P6 present highest light harvesting efficiency (LHE), driving force of electron injection ( $\Delta G^{inject}$ ), reorganization energy ( $\Delta G_{reg}$ ) and $e{V}_{OC}$ . These critical parameters have a close relationship with the short-circuit current density ( $J_{SC}$ ) and open-circuit photovoltage ( $V_{OC}$ ), and lead to P1–P6 will exhibit higher efficiency. D4 also exhibit superior properties in the driving force of electron injection ( $\Delta G^{inject}$ ), reorganization energy ( $\Delta G_{reg}$ ), which will lead to a higher short-circuit current density ( $J_{SC}$ ). We hope that these results will be helpful for experiments to synthesize new and highly efficient dyes. Full article

We report single crystal X-ray diffraction (hereafter, SCXRD) analyses of derivatives featuring the electron-donor N-ethylcarbazole or the (4-diphenylamino)phenyl moieties associated with a -CN group attached to a double bond. The compounds are (2Z)-3-(4-(diphenylamino)-phenyl)-2-(pyridin-3-yl)prop-2-enenitrile (I), (2Z)-3-(4-(diphenylamino)phenyl)-2-(pyridin-4-yl)-prop-2-enenitrile (II) and (2Z)-3-(9-ethyl-9H-carbazol-3-yl)-2-(pyridin-2-yl)enenitrile (III). SCXRD analyses reveal that I and III crystallize in the monoclinic space groups P2/c with Z’ = 2 and C2/c with Z’ = 1, respectively. Compound II crystallized in the orthorhombic space group Pbcn with Z’ = 1. The molecular packing analysis was conducted to examine the pyridine core effect, depending on the ortho, meta- and para-positions of the nitrogen atom, with respect to the optical properties and number of independent molecules (Z’). It is found that the double bond bearing a diphenylamino moiety introduced properties to exhibit a strong π-π-interaction in the solid state. The compounds were examined to evaluate the effects of solvent polarity, the role of the molecular structure, and the molecular interactions on their self-assembly behaviors. Compound I crystallized with a cell with two conformers, anti and syn, due to interaction with solvent. DFT calculations indicated the anti and syn structures of I are energetically stable (less than 1 eV). Also electrochemical and photophysical properties of the compounds were investigated, as well as the determination of optimization calculations in gas and different solvent (chloroform, cyclohexane, methanol, ethanol, tetrahydrofuran, dichloromethane and dimethyl sulfoxide) in the Gaussian09 program. The effect of solvent by PCM method was also investigated. The frontier HOMO and LUMO energies and gap energies are reported. Full article