Charge-Separated States Determined Photoinduced Electron Transfer Efficiency in a D-D-A System in an External Electric Field

Abstract

Focusing on the photoinduced electron transfer properties of the D-D-A molecule ((TPA-TT)-BODIPY-C 60 ) in an external electric field (F ext ), the excited-state properties in which the double-donor molecule is excited to form three chargeseparated states were simulated. The charge-transfer processes of these three charge-separated states were investigated by considering the two donors as a whole ((TPA-TT-BODIPY)• + -C 60 • − ) as a comparison object. The electronic coupling (V DA ), reorganization energy (λ), and free energy (ΔG) of the different charge-separated states in F ext were calculated and simulated. The calculated results show that the λ of (TPA-TT-BODIPY)• + -C 60 • − ranges from 0.576 to 0.51 eV, and the calculated ΔG of exciton dissociation ranges from −1.402 to −1.143 eV, indicating that exciton dissociation occurs in the Marcus inverted region. In the range of F ext = −10 × 10 −5 to 10 × 10 −5 au, the trend of the charge-transfer rate is gradually increasing, and the rate increase is mainly from the V DA and ΔG changes. Moreover, the rapid formation of the (TPA-TT)-BODIPY• + -C 60 • − charge-separated state and the formation of the long-lived (TPA-TT)• + -BODIPY-C 60 • − are indicated by the exciton dissociation rate. By studying the charge-transfer parameters under different electric field directions, it is found that the regulation of electric field strength on the charge-transfer rate is consistent. These results provide a feasible method for the rational design of a new type of electron transfer process with high efficiency of the D-D-A system.

Directionality and additivity effects of molecular acidity and aromaticity for substituted benzoic acids under external electric fields

“…That is, the change of NICS(0) values due to the introduction of substituting groups comes from the sum of the change of individual groups. For doubly substituted derivatives, it follows eqn (10), and for triply substituted benzoic acids, eqn (11) is Table 3 Statistical analysis results of the fitted pK a values using the additivity effect for doubly and triply cyano-substituted benzoic acid derivatives under external electric field along x-and y-axes, including correlation coefficient R 2 , mean squared error (MSE), root-mean-square error (RMSE), and mean absolute error (MAE) between the calculated and fitted pK a values…”

“…That is, the weight of eqn (9) is generally not normalized. For example, for the NICS(0) value, NICS(0) mp , of the doubly substituted benzoic acid at meta-and para positions, we have NICS(0) mp = NICS(0) 0 + a m DNICS(0) m + a p DNICS(0) p , (10) where NICS(0) 0 denotes the NICS(0) value of the unsubstituted benzoic acid, DNICS(0) m and DNICS(0) p represent the NICS(0) change of the singly substituted species at meta and para positions, respectively, and a m and a p are their respective coefficients. Similarly, for triply substituted species with one at each of the two meta positions and another at the para position, it becomes…”

“…Essential in many chemical and physical phenomena and processes, the impact of external fields has attracted noticeable attention lately in the literature [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] because it can influence the molecular structure, [17][18][19][20][21][22] chemical reactivity, [23][24][25][26][27][28] and other electronic properties. [29][30][31][32][33][34] In a previous study, we investigated the impact of uniform external electric fields on molecular acidity and aromaticity propensities for the benzoic acid molecule.…”

Sonocatalytic cancer therapy: theories, advanced catalysts and system design

“…In these explosive cavitation bubble events, enormous heat and pressure energies are yielded due to the conversion of mechanical energy. 22 Based on the extremely high heat generated by inertial cavitation, two potential fundamental mechanisms have been proposed, sonoluminescence and pyrolysis, to account for ROS generation in sonochemical reactions. 23,24 Sonoluminescence refers to the emission of light produced by the implosive collapse of cavitation bubbles induced by ultrasound.…”

“…Thus, ultrasonic energy is converted into heat, elevating the tissue temperature, the wellknown ultrasonic thermal effect. 22…”