The geometric structures, energetic and electronic properties of global minima of the AlBen (n = 1–12) clusters have been systemically studied by using the hybrid density functional theory [B3LYP] and coupled cluster [CCSD(T)] methods. It is found that the impurity Al atom is externally bound to the host Ben framework and its maximum coordination number is six. Besides, the geometries of AlBen bear close resemblance to either local or global minimum structures of Ben+1. The AlBe3 and AlBe8 clusters exhibit high relative stability among the AlBen clusters, which is reflected by the evolutions of average atomic binding energy, dissociation energy, second difference in energy, adsorption energy of Al, and HOMO-LUMO gap with cluster size. In comparison to the pure Ben+1 clusters, AlBen exhibit larger binding energy values, whereas they are more polarizable.
Electrochemotherapy is an effective strategy for the treatment of solid tumors by exposing tumor cells to electric fields to enhance the bioactivity of non-permeable or low permeable anticancer drugs, such as cisplatin. To understand the improved efficiency of cisplatin in electrochemotherapy, the effects of oriented external electric fields (OEEFs) on the geometric structures and relevant electronic properties of cisplatin have been systemically investigated by density functional theory (DFT) computations in this work. Our results reveal that the presence of positive OEEFs on cisplatin can not only weaken its Pt-Cl bonds, but also enhance the intramolecular charge transfer in it, which effectively accelerates the critical hydrolysis step involved in the mechanism of its biological activity. Moreover, the positive OEEFs can facilitate the attack of the singly aquated cis-[Pt(NH3)2(H2O)Cl]+ on DNA, and enlarge the dipole moments and water solubility of cisplatin and its aquated product. Consequently, this work provides a deeper insight into the higher efficacy of electrochemotherapy than traditional chemotherapy from a molecular point of view.
A intriguing type of excess electron compounds simultaneously containing electride and alkalide characteristics was obtained on the basis of the synthesized facially polarized molecule all-cis 1,2,3,4,5,6-hexafluorocyclohexane (1). By doping the two different faces of this Janus molecule with an alkaline earth atom and an alkali-metal atom, a series of M-1-M’ (M = Be, Mg, and Ca; M’ = Li, Na, and K) compounds were firstly achieved. Our calculated results show that, different from Be and Mg, one 4s electron of Ca can be transferred to the upper alkali metal atoms forming an alkali metal anion while the remaining 4s electron was push away from Ca+ yielding an electron anion by the instinctive facial polarization of 1 or with the assist of oriented external electric fields (OEEFs). Owing to the existence of two loosely bound excess electrons in the resulting Ca+-1-M’− (M’ = Li, Na, and K), these novel compounds exhibit extremely large first hyperpolarizabilities (β0) of 9.94 × 105‒1.81 × 106 au. Thus, we hope that this work could provide the first members with both of electride and alkalide characteristics to further enrich the family of excess electron compounds.