The antimonato-polyoxovanadate {Ni(en)}[VSbO(HO)]·ca.15HO was utilized as a synthon for the solvothermal in situ generation of the new compound {Ni(phen)}[{Ni(en)}VSbO(HO)]·19HO, a rearrangement induced by ligand metathesis. While in the precursor structure cations and anions are isolated, the solid-state structure of the product is characterized by 1D chains consisting of alternating [VSbO(HO)] cluster shells and [Ni(en)] units covalently linked to neighboring clusters via terminal oxygen atoms. Water clusters composed of sixteen hydrogen-bonded HO molecules are located in void spaces of the structure. The magnetic properties indicate weak antiferromagnetic interactions of the bridging Ni center and adjacent polyoxovanadate anions, as well as small magnetic anisotropy of the individual Ni centers.

In situ monitoring of the formation of emissive complexes is essential to enable the development of rational synthesis protocols, to provide accurate control over the generation of structure-related properties (such as luminescence) and to facilitate the development of new compounds. In situ luminescence analysis of coordination sensors (ILACS) utilizes the sensitivity of the spectroscopic properties of lanthanide ions to their coordination environment to detect structural changes during crystallization processes. Here, ILACS was utilized to monitor the formation of [Eu(bipy)(NO)] (bipy = 2,2'-bipyridine) during co-precipitation synthesis. Validity of the ILACS results was ensured by concomitant utilization of in situ monitoring of other reaction parameters, including in situ measurements of pH value, ionic conductivity, and infrared spectra, as well as ex situ and synchrotron-based in situ X-ray diffraction analyses. Gradual desolvation of the Eu ions and attachment of ligands were detected by an exponential increase of the intensity of the D → F (J = 0-4) transitions in the emission spectrum. Additionally, the in situ emission spectra show a decrease in the crystallization rate and an increase in the induction time in response to a reduction in the concentration of the starting solutions from 12 mM until crystallization ceased at starting reactant concentrations <6 mM. An increase to a three-fold higher concentration leads to the formation of a reaction intermediate, and its stability was determined to be highly concentration-dependent. The in situ luminescence measurements also demonstrated the existence of a ligand exchange process within the [Eu(bipy)(NO)] complex upon addition of a phen (phen = 1,10'-phenanthroline) solution and the generation of a new phen-containing emissive complex. In attempting to solve the structure of this new phen-containing complex, a different, but nevertheless previously unsynthesized complex, [Eu(phen)(NO)]bipy, was obtained, which shows characteristic Eu luminescence in the red spectral range.

Despite the strong technological importance of lanthanide complexes, their formation processes are rarely investigated. This work is dedicated to determining the influence of synthesis parameters on the formation of [Ce(bipy)2(NO3)3] as well as Ce3+‐ and Tb3+‐substituted [La(bipy)2(NO3)3] (bipy = 2,2′‐bipyridine) complexes. To this end, we performed in situ luminescence measurements, synchrotron‐based X‐ray diffraction (XRD) analysis, infrared spectroscopy (IR), and measured pH value and/or ion conductivity during their synthesis process under real reaction conditions. For the [Ce(bipy)2(NO3)3] complex, the in situ luminescence measurements initially presented a broad emission band at 490 nm, assigned to the 5d→4f Ce3+ ions within the ethanolic solvation shell. Upon the addition of bipy, a red shift to 700 nm was observed. This shift was attributed to the changes in the environment of the Ce3+ ions, indicating their desolvation and incorporation into the [Ce(bipy)2(NO3)3] complex. The induction time was reduced from 8 to 3.5 min, by increasing the reactant concentration by threefold. In contrast, [La(bipy)2(NO3)3] crystallized within days instead of minutes, unless influenced by high Ce3+ and Tb3+ concentrations. Monitoring and controlling the influence of the reaction parameters on the structure of emissive complexes is important for the development of rational synthesis approaches and optimization of their structure‐related properties like luminescence.

Polymer microparticles that have pollen-like surface structures can be prepared by the evaporation of an oilin-water emulsion. Here, polystyrene, polysulfone and PMMA was dissolved in ethyl acetate (the oil phase) and mixtures of those were emulgated in aqueous solutions of various emilsifiers. The polymer particles show surface structures, and we found that polysulfone makes hemispherical protrusions in various mixtures with polystyrene or PMMA.

The cover picture shows the real‐time investigation of the crystallization mechanism of lanthanide complexes containing Ce with 2,2‐bipyridine ligands by means of in situ X‐ray diffraction analysis measured at the German Electron Synchrotron DESY. Complementary measurements applying the so‐called in situ luminescence analysis of coordination sensors (ILACS) approach allow to additionally monitor the desolvation process of the Ce3+ cations prior to crystallization. The combination of multiple in situ characterization methods during crystallization enables understanding what happens not only inside the solid material but also its interaction with the liquid medium surrounding it. Details are discussed in the article by Jonas Ströh et al. on page 537.