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Macroscopic scale hollow microcrystals are a promising group of materials for gas and liquid uptake as well as sensing. In this contribution we describe the structure of hollow hexagonal cross-section crystals formulated as salts of a silicon catecholate anion and a tetramethylenediamine (TEMED) cation. Using a combination of X-ray single crystal diffraction, Raman spectroscopy and quantum chemistry we explore the structural properties of the hollow microcrystals. With the X-ray structural data as a starting point and assisted with quantum chemistry we compute Raman tensors to fit polarisation sensitive spectral responses and predict the orientation and packing of unit cells in respect to the long and short axis of the synthesised microcrystals. Using these newly developed methods for predicting molecular Raman responses in space with dependence on local orientation, we present the quantitative analysis of experimental Raman images of both hexagonal and tetragonal cross section hollow microcrystals formed from silicon catecholate anions using different amines as counterions. We describe the distributions of chemical components at the surfaces and edges of microcrystals, address the effect of catcholate hydrophobicity on water uptake and discuss possible strategies in chemical and post-assembly modifications to widen the functional properties of this group of environmentally friendly silicon organic framework (SOF) materials. [ABSTRACT FROM AUTHOR]

A new approach to analyze band-gap and defect states within semiconductors is reported. Solid state excitation-emission matrices are used to deconvolve spectral signatures that will be superimposed in 1D spectral space; for example, the 570 nm emission peak in ZnO whose emissive state is of a different physical nature depending on the excitation wavelength used. The broad applicability of the technique is shown for a library of widely studied inorganic semiconductors CdS, CdSe, ZnS, ZnSe, ZnO (analytical standard and nanorods), and TiO2. Anthracene is included as a representative example of an organic semiconductor. The developed approach can identify spectral features from the band gap, defects, and trace impurities and provide information on the relative contributions of the different emission pathways. The technique, based on using a plate-reader conventionally used for the study of biological samples in solution has applicability in both academic and industrial settings for semiconductor studies and quality control applications. [ABSTRACT FROM AUTHOR]

Nanomaterials have been the object of intense study due to promising applications in a number of different disciplines. In particular, medicine and biology have seen the potential of these novel materials with their nanoscale properties for use in diverse areas such as imaging, sensing and drug vectorisation. Gold nanoparticles (GNPs) are considered a very useful platform to create a valid and efficient drug delivery/carrier system due to their facile and well-studied synthesis, easy surface functionalization and biocompatibility. In the present study, stable antibiotic conjugated GNPs were synthesised by a one-step reaction using a poorly water soluble antibiotic, amoxicillin. Amoxicillin, a member of the penicillin family, reduces the chloroauric acid to form nanoparticles and at the same time coats them to afford the functionalised nanomaterial. A range of techniques including UV-vis spectroscopy, dynamic light scattering (DLS), transmission electron microscopy (TEM) and thermogravimetric analysis (TGA) were used to ascertain the gold/drug molar ratio and the optimum temperature for synthesis of uniform monodisperse particles in the ca. 30-40 nm size range. Amoxicillin-conjugated gold showed an enhancement of antibacterial activity against Escherichia coli compared to the antibiotic alone. Keywords Gold * Nanoparticles * Amoxicillin * Escherichia coli * Antibacterial activity, Introduction Since the discovery of the first antibiotic [1], the scientific community has spent a great amount of effort in studying, developing and synthesising new types of antibiotic to fight [...]

Complexes of Cu2+(d9) with proline may be considered a simple model to address the structural flexibility and electronic properties of copper metalloproteins. To discuss optical electronic spectra and infrared spectral responses, we use quantum chemistry applied to model systems prepared under different geometries and degree of hydration. A comparison of experimental data with calculations indicates that first explicit neighbor water clustering next to the Cu2+(d9) complex is critical for a correct description of the electronic properties of this system. We deduce that the moderately hydrated trans conformer is the main structural form of the complex in water. Further, we suggest that the antisymmetric stretching mode of the carbonyl moieties of the conformer is dominant in the spectrally broadened infrared resonance at 1605 cm−1, where inhomogeneity of the transition at the blue side can be ascribed to a continuum of less optimal interactions with the solvent. Extracted structural properties and hydration features provide information on the structural flexibility/plasticity specific to Cu2+(d9) systems in correlation with the electronic behavior upon photoexcitation. We discuss the role and the nature of the axial ligand in bio-copper structural ambivalence and reactivity. [ABSTRACT FROM AUTHOR]

The theoretical and experimental studies of silica formation are conducted utilizing biological and model organic additives to understand the roles of hydroxyl-containing biomolecules in biosilicification. The results demonstrate that in aqueous systems, the effect of hydroxyl-containing additives is negligible.