Three Types of Mixed Alkali‐Metal‐, Transition‐Metal‐, or Rare‐Earth‐Substituted Sandwich‐Type Arsenotungstates with Supporting Rare‐Earth Pendants

Abstract

Three types of mixed alkali‐metal‐, transition‐metal‐, or rare‐earth‐substituted sandwich‐type arsenotungstates with supporting rare‐earth pendants, namely, [La(H2O)8]2H[K2LaCu3(H2O)9][B‐α‐AsW9O33]2·17H2O (1), Na2K0.5RE0.5[RE(H2O)8][K3Cu2WO(H2O)10][B‐α‐AsW9O33]2·14H2O [RE = Pr3+ (2), Nd3+ (3), Sm3+ (4), Eu3+ (5)], and K2H[Pr(H2O)6][Pr(H2O)7][K2NaCu3(H2O)7][B‐α‐AsW9O33]2·18H2O (6), were synthesized in aqueous solution. The utilization of different alkali‐metal cations led to the formation of three structural types. If only K+ cations were utilized in the system, 1 was obtained, whereas 2–6 formed when Na+ and K+ cations were used. In addition, the common characteristic of 1–6 is that they consist of hexanuclear heterometal‐substituted sandwich‐type arsenotungstate structural units, and the hexanuclear heterometallic clusters in the central belt are distributed in a triangular fashion. The solid‐state photoluminescence spectra of 2, 3, 4, and 5 at ambient temperature are mainly derived from the f–f electron transitions of the RE cations. The drug activities of 4 and 5 were measured through 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide (MTT) assays, and the results demonstrate that 4 can induce the apoptosis of HepG2 cells and HCT‐116 cells through the activation of caspase‐3 and the autophagy of HepG2 cells and HCT‐116 cells through the involvement of lysosomes. The coexistence of apoptosis and autophagy leads to the death of cancer cells.