In this work, we applied an external electric field (F) to a biphenalenyl derivative (BN-PLY) in the direction of the negative z-axis (F) and the positive z-axis (F), respectively. The influence of the two directions of F on the molecular structures and electronic properties is investigated, which gives interesting results. Density functional theory (DFT) calculations show that the application of F (F = 0 to -190 × 10) is an advantage toward improving π-dimer stability, which is attributed to an increase in bonding and attractive electrostatic interactions. Interestingly, a large amount of negative charge is induced by applying F to the upper layer, resulting in an increase in the electron density in the upper layer, which is the main factor for the formation of a symmetric highest occupied molecular orbital (HOMO) at F = -180 × 10 au (-9.26 × 10 V m). Moreover, when F is applied, the HOMO and HOMO-1 undergo orbital interchange in the π-dimer at F = 100/110 × 10 au. Significantly, the effect of the external electric field effectively regulates the first hyperpolarizabilities (β). When the F ranges from 0 to 140 × 10 au, the β values slightly decrease to 0 au. Note that, upon increasing F, the β values sharply increase to 6.67 × 10 au (F = 190 × 10 au). Furthermore, the evolutions of the absorption spectra under F might well explain the trend of β values. When the F ranges from 0 to 140 × 10 au, the broad absorption spikes with a low-energy are significantly blue-shifted, while only absorption spikes with a high-energy are significantly red-shifted (F = 140 to 190 × 10 au). The present work not only provides a deeper understanding of the relationships between the molecular structure and the electronic properties of a π-dimer system, but can also be developed for designing highly efficient nonlinear optical materials through the influence of an external electric field.

Phenalenyl π-dimer (PLY 2 ) has recently attracted intensive research interest due to its unique structure and binding characteristics (two-electron/12-center bonding). The directional transfer of electron or electron pair under the external electric field can produce a new structure with interesting properties. In the present work, we investigate for the first time the effect of the external electric field along the main molecule axis on PLY 2 . Two unpaired electrons between two layers are gradually shifted to the upper layer with increasing of the external electric field strength (F ext): the weaker the two-electron/12-center bonding, the stronger the electrostatic interaction between two layers. Significantly, a small increment of F ext makes a big difference: the interlayer distance in the PLY 2 is sharply elongated from 3.241 Å (F ext = 203 × 10–4 au) to 3.485 Å (F ext = 204 × 10–4 au), which leads to the two-electron/12-center bonding breaking at 204 × 10–4 au. Therefore, the F ext = 204 × 10–4 au is regarded as the critical electric field. In this case, the interaction between two layers in PLY 2 is exclusively governed by the electrostatic interaction. Besides this, the effect of the external electric field brings some distinctive changes in its diradical character (y 0), the Wiberg bond index (WBI), the interaction energy (E int), and the frontier molecular orbital (FMO) that can be used to explore the conversion between bonding and electrostatic interactions. This study can deepen the understanding for the effect of the external electric field on structures and electric properties for molecule and be an open a door for the discovery and development of new switching devices.

An interesting biphenalenyl biradicaloid (IDPL) dimer consisting of both-middle superimposed phenalenyls and both-end nonsuperimposed phenalenyls has been synthesized, and has attracted intensive research interest due to its intra- and intermolecular interactions and semiconductive characteristics. It is significant that under regulation of the external electric field the directional charge transfer (CT) can produce attractive properties. In the present work, the structure and electronic properties of the IDPL dimer under an external electric field (along the horizontal Fx or the vertical Fz directions) are explored, and the following properties determined: (i) as the horizontal Fx increases, the intramolecular CT becomes larger, which induces the intermolecular CT of the IDPL dimer. (ii) In contrast, as the vertical Fz increases, the large intermolecular CT gives rise to the intramolecular CT of the IDPL dimer. (iii) More importantly, the external electric field effectively regulates and controls the first hyperpolarizability (βtot) of the IDPL dimer. Compared with the vertical Fz, the horizontal Fx induces a larger first hyperpolarizability (βtot = 5.48 × 105 a.u.). Furthermore, the application of a uniform external electric field (Fx,y,z) to the IDPL dimer was investigated to define the external electric field direction of the material application. The βtot values were increased with increasing of the uniform Fx,y,z. Our study provides an effective strategy for developing high-performance NLO materials by tuning the external electric field, and could be of significance for application in switch devices.

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Based on s-indaceno [1,2,3-cd;5,6,7-c′d′]diphenalene (1) consisting of two phenalenyl moieties, the monomer 2 and its dimer 2 2 are designed by boron and nitrogen atoms substituting the central carbon atoms of phenalenyl moieties. Calculated energy decompose analysis (EDA) shows that the orbital interaction for 2 2 possesses a large attractive contribution of −18.31 kcal mol −1 , which is dominated by the π−π stacking interaction between the upper and the lower π-conjugated units. Interestingly, the natural population analysis (NPA) charge and the transition density matrix (TDM) show that both intramolecular charge transfer and intermolecular charge transfer (CT) exist in 2 2 . Further, the first hyperpolarizability (β tot = 4.56 × 10 4 au) of 2 with intramolecular CT is greatly larger than that of reported molecule 3 (5.45 × 10 3 au) with intermolecular CT. Significantly, 2 2 exhibits the largest β tot value to be 1.42 × 10 5 au, which is caused by combining the intra-and intermolecular CT transitions (β x = 1.40 × 10 5 au and β z = 2.27 × 10 4 au). Correspondingly, highest occupied molecular orbital (HOMO) → lowest unoccupied molecular orbital (LUMO) (intramolecular CT) in the low-energy electronic transition of 2 2 is 68%, while HOMO → LUMO + 1 (intermolecular CT) is 18%, which demonstrates that the intramolecular CT effect on the β tot value is stronger than the case of the intermolecular CT effect. The present work might provide rich insight into designing and developing potential second-order optical nonlinearity materials with inter-and intramolecular CT characters.

Objective: The aim of this research was to investigate the therapeutic efficacy of lenvatinib combined with sequential transarterial chemoembolization (TACE) on primary hepatocellular carcinoma (HCC) and the effects on serum basic fibroblast growth factor (bFGF) and vascular endothelial growth factor (VEGF).Method: A total of 104 patients with primary HCC, admitted to People’s Hospital of Leshan from April 2018 to January 2021, were selected as the study subjects and were divided into the TACE-LEN group (n = 53) who were treated with lenvatinib combined with sequential TACE and the TACE group (n = 51) who were treated with TACE alone, according to the appropriate treatment modalities. The clinical efficacy 8 weeks after treatment; the serum levels of total bilirubin, conjugated bilirubin, and alanine aminotransferase (ALT); the prothrombin time (PT); the indocyanine green retention rate at 15 min (ICGR15); and the serum bFGF and VEGF levels before treatment and at 8 weeks after treatment were compared between the two groups. The incidence of adverse events and the survival rates at 18 months were also recorded for both groups. COX regression analysis was used to analyze the risk factors affecting the survival of patients.Results: Eight weeks after treatment, the objective response rate was higher in the TACE-LEN group than in the TACE group (77.36% vs. 56.36%, p < 0.05), but there were no statistically significant differences in the bilirubin and ALT levels, the PT, and the ICGR15 between the two groups (p > 0.05). The serum bFGF and VEGF levels post-therapeutic were lower in the TACE-LEN group than in the TACE group (p < 0.05). The differences in the incidence of postoperative adverse events and the survival rate within 6 months were not statistically significant between the two groups (p > 0.05). In addition, the survival rates within 12 and 18 months after treatment were higher in the TACE-LEN group than in the TACE group than in the TACE group (81.1% vs. 64.7%, 69.8% vs. 49.1%, p < 0.05). ICG-R15 and treatment regimen are risk factors for survival.Conclusion: The worse the liver reserve is, the worse the prognosis is. The combination of TACE and lenvatinib showed better efficacy and longer survival than TACE monotherapy for HCC patients and reduced the levels of bFGF and VEGF.

Very recently, two new cage-like radicals (C59B and C59N) formed by a boron or nitrogen atom substituting one carbon atom of C60 were synthesized and characterized. In order to explore the structure-property relationships of combination the cage-like radical and alkali metal, the endohedral Li@C59B and Li@C59N are designed by lithium (Li) atom encapsulated into the cage-like radicals C59B and C59N. Further, the structures, natural bond orbital (NBO) charges, and nonlinear optical (NLO) responses of C59B, C59N, Li@C59B, and Li@C59N were investigated by quantum chemical method. Three density functional methods (BHandHLYP, CAM-B3LYP, and M05-2X) were employed to estimate their first hyperpolarizabilities (β tot) and obtained the same trend in the β tot value. The β tot values by BHandHLYP functional of the pure cage-like radicals C59B (1.30 × 10(3) au) and C59N (1.70 × 10(3) au) are close to each other. Interestingly, when one Li atom encapsulated into the electron-rich radical C59N, the β tot value of the Li@C59N increases to 2.46 × 10(3) au. However, when one Li atom encapsulated into the electron-deficient radical C59B, the β tot value of the Li@C59B sharply decreases to 1.54 × 10(2) au. The natural bond orbital analysis indicates that the encapsulated Li atom leads to an obvious charge transfer and valence electrons distribution plays a significant role in the β tot value. Further, frontier molecular orbital explains that the interesting charge transfer between the encapsulated Li atom and cage-like radicals (C59B and C59N) leads to differences in the β tot value. It is our expectation that this work will provide useful information for the design of high-performance NLO materials.

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