Synthesis, Characterization, and High-Pressure Studies of a 3D Berkelium(III) Carboxylate Framework Material

A berkelium(III) mellitate, Bk2[C6(CO2)6](H2O)8∙2H2O, was synthesized and rapidly crystallized by reacting mellitic acid, C6(CO2H)6, and BkBr3∙nH2O in an aqueous medium. Single crystal X-ray diffraction shows that the compound crystallizes as...

Distance makes a difference in crystalline photoluminescence

Crystallization-induced photoluminescence weakening was recently revealed in ultrasmall metal nanoparticles. However, the fundamentals of the phenomenon are not understood yet. By obtaining conformational isomer crystals of gold nanoclusters, we investigate crystallization-induced photoluminescence weakening and reveal that the shortening of interparticle distance decreases photoluminescence, which is further supported by high-pressure photoluminescence experiments. To interpret this, we propose a distance-dependent non-radiative transfer model of excitation electrons and support it with additional theoretical and experimental results. This model can also explain both aggregation-induced quenching and aggregation-induced emission phenomena. This work improves our understanding of aggregated-state photoluminescence, contributes to the concept of conformational isomerism in nanoclusters, and demonstrates the utility of high pressure studies in nanochemistry.

Polymorphism and structure–property relations

Chapter 6 deals with the connection between the structure and properties of solids as revealed and studied in polymorphic systems. The subject is divided into properties that depend on the one hand on the bulk—that is, the three-dimensional arrangement of the molecules and the interactions among them—and on the other hand the consideration of the crystal as an “oriented gas” serving to act as a matrix for the molecules to permit the study of molecular properties. Among the properties described in the former category are electrical conductivity, organic magnetic materials, photovoltaicity and photoconductivity, second harmonic generation, chromoisomerism, photochromism, thermochromism and mechanochromism, and the mechanosalient effect. The latter category includes a discussion of spectroscopic studies (infrared, Raman, and ultraviolet/visible), excimer phenomena, time-resolved studies of excited states, photochemical reactions and thermal and gas reactions, along with a variety of emission phenomena. The chapter closes with a brief survey of rapidly emerging and developing high pressure studies