We discuss how our results complement and extend recent findings on the crystallization of ZIF-8 with SOD topology under similar synthetic conditions. The reaction kinetics speeds up with increasing linker-to-metal concentration ratio, yielding nanocrystals with decreasing size, while the life times of amorphous intermediates become very short and challenging to be observed experimentally. The latter particles transform into the periodic ZIF-71 structure with RHO topology, probably via intraparticle nucleation and subsequent particle reorganization. By taking advantage of the combined use of time-resolved static and dynamic light scattering and stopped-flow synchrotron small-angle and wide-angle X-ray scattering, we were able to reveal the whole nanocrystal formation process: a population of small amorphous particles (termed clusters) first forms via coagulation, followed by the formation of a second population of bigger amorphous particles that grow via addition of significantly smaller "monomers", the nature of which remains as yet unknown (clusters and/or smaller units). In a dynamic light scattering measurement, the time-dependent fluctuations in the scattered light are measured by a fast photon counter. In this contribution, we present the results of in situ studies on a recently developed fast ZIF-71 nanocrystal synthesis from solution. Information such as size, molecular weight, diffusion and interaction strength are obtained. But, the number of particles analyzed by AFM is much smaller, consequently, DLS offers an improved size distribution. Dynamic light scattering (DLS), also known as photon correlation spectroscopy (PCS), is a commonly used characterization method for nanoparticles. The current rather poor understanding of the mechanisms of crystallization of zeolitic imidazolate frameworks (ZIFs), an important subclass of porous metal organic framework (MOF) materials, greatly hampers rational synthesis of predicted ZIF phases/polymorphs and control of crystal size/shape. Static and Dynamic Light Scattering (SLS/DLS) Light scattering is a well established technique to investigate properties of particles in solutions.
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