Antimony and bismuth ⟨111⟩ layered perovskites have recently attracted significant attention as possible, nontoxic alternatives to lead halide perovskites. Unlike lead halide perovskites, however, ⟨111⟩ halide perovskites have shown limited ability to tune their optical and electronic properties. Herein, we report on the metal alloying of manganese and copper into the family of materials with formula Cs 4 Mn 1−x Cu x Sb 2 Cl 12 (x = 0−1). By changing the concentration of manganese and copper, we show the ability to modulate the bandgap of this family of compounds over the span of 2 electron volts, from 3.0 to 1.0 eV. Furthermore, we show that in doing so, we can also adjust other relevant properties such as their magnetic behavior and their electronic structure.

Generation of soluble sources of peroxide dianion (O(2)(2-)) is a challenge in dioxygen chemistry. The oxidizing nature of this anion renders its stabilization in organic media difficult. This Report describes the chemically reversible reduction of oxygen (O(2)) to cryptand-encapsulated O(2)(2-). The dianion is stabilized by strong hydrogen bonds to N-H groups from the hexacarboxamide cryptand. Analogous stabilization of peroxide by hydrogen bonding has been invoked recently in crystalline saccharide and protein systems. The present peroxide adducts are stable at room temperature in dimethyl sulfoxide (DMSO) and N,N'-dimethylformamide (DMF). These adducts can be obtained in gram quantities from the cryptand-driven disproportionation reaction of potassium superoxide (KO(2)) at room temperature.

The peroxide dianion reacts with CO2 in polar aprotic organic media to afford the hydroperoxycarbonate and carbonate radical anions. These highly reactive species, if formed in lithium–O2 cells, can lead to cell degradation via oxidation of the electrolyte and electrode.

A series of isostructural compounds with formula [M(TCNQF(4))(2)(H(2)O)(6)]TCNQF(4)3 H(2)O (M=Tb (1), Y (2), Y:Tb (74:26) (3), and Y:Tb (97:3) (4); TCNQF(4)= tetrafluorotetracyanoquinodimethane) were prepared and their magnetic properties investigated. Compounds 1, 3, and 4 show the beginning of a frequency-dependent out-of-phase ac signal, and decreasing intensity of the signal with decreased concentration of Tb(III) ions in the diluted samples is observed. No out-of-phase signal was observed for 2, an indication that the behavior of 1, 3, and 4 is indicative of slow paramagnetic relaxation of Tb(III) ions in the samples. A more detailed micro-SQUID study at low temperature revealed an interplay between single-molecule magnetic (SMM) behavior and a phonon bottleneck (PB) effect, and that these properties depend on the concentration of diamagnetic yttrium ions. A combination of SMM and PB phenomena was found for 1, whereby the PB effect increases with increasing dilution until eventually a pure PB effect is observed for 2. The PB behavior is interpreted as being due to the presence of a "sea of organic S=1/2 radicals" from the TCNQF(4) radicals in these compounds. The present data underscore the fact that the presence of an out-of-phase ac signal may not, in fact, be caused by SMM behavior, particularly when magnetic metal ions are combined with organic radical ligands such as those found in the organocyanide family.