Surface-charge-induced freezing of colloidal suspensions

Using grand-canonical Monte Carlo simulations we investigate the impact of charged walls on the crystallization properties of charged colloidal suspensions confined between these walls. The investigations are based on an effective model focussing on the colloids alone. Our results demonstrate that the fluid-wall interaction stemming from charged walls has a crucial impact on the fluid's high-density behavior as compared to the case of uncharged walls. In particular, based on an analysis of in-plane bond order parameters we find surface-charge-induced freezing and melting transitions

Fast Microscopic Method for Large Scale Determination of Structure, Morphology, and Quality of Thin Colloidal Crystals

We present a novel fast microscopic method to analyze the crystal structures of air-dried or suspended colloidal multilayer systems. Once typical lattice spacings of such films are in the range of visible light, characteristic Bragg scattering patterns are observed. If in microscopic observations these are excluded from image construction, a unique color coding for regions of different structures, morphologies, and layer numbers results. Incoherently scattering defect structures, however, may not be excluded from image construction and thus remain visible with high resolutio

Novel Layering of Aqua and Imidazolidinyl Phenolate Bridged Cationic [CuII 2(μ-L)(μ-H2O) 3H2O]2 Units Over CuINCS Based One-Dimensional Anionic Parallel Chains as Diamagnetic Coordination Framework Host

The hetero valence copper-based metal-organic framework structure {[CuII2(μ-L)(μ-H2O) 3H2O][CuI- (1,3-NCS)2]}n (2) was constructed from the aqua-bridged [Cu2] complex [Cu2(μ-L)(μ-H2O)]ClO4 3 1.5H2O (1 3 1.5H2O) of the N4O3 coordinating heptadentate imidazolidinyl phenolate Schiff base ligand, H3L (2-(20hydroxyphenyl)-1,3-bis[4-(2-hydroxyphenyl)-3-azabut-3-enyl]-1,3-imidazolidine). Thiocyanate coordination induced aqua bridge cleavage and reductive extrusion lead to the formation of Cu(NCS)2 - anions as a molecular building block and generation of one-dimensional (1D) anionic chains as an extended coordination framework host in 2 and quantitatively replace all the ClO4 - ions from 1 3 1.5H2O via anion metathesis. Once formed these chains trap the original [Cu2] cationic units in a layer. The copper atoms of 2 are in a distorted square-pyramidal environments around copper ions and are held together by phenolate, imidazolidinyl, and aqua bridges at 3.29 A ° intrametallic CuII 3 3 3 CuII separation. Within the anionic part the presence of two “symmetric” end-to-end thiocyanate bridges with CuI-SCN and CuI-NCS distances of 2.61 A ° (av.) and 1.924 A ° (av.), respectively, results in a CuI 3 3 3 CuI separation of 5.51 A ° (av.) within the linear chain. The cationic part of 2 exhibits a weak ferromagnetic exchange interaction (J/kB=þ13.0(5) K or J=þ9.0 cm-1 and g=2.25(1)) between the two CuII ions (S=1/2) and implies that the complex possesses an ST=1 spin ground state in good agreement with theMvs H data below 8 K