Exposure of mass-selected bimetallic Pt–Ti nanoalloys to oxygen explored using scanning transmission electron microscopy and density functional theory

Theoretical and experimental morphology induced by oxidation of the Ti element.

Morphology of L-Alanine Crystal, Associated with its Interaction with Glycine Additive: A Molecular Modelling and Experimental Study

. In this paper, L-alanine crystal was crystallized in the presence and absence of glycine additive using slow evaporation method, in association with a simulation technique using ab-initio quantum mechanical method used to predict the crystal morphology of L-alanine. Comparison between the experimental and simulated lattice energies have shown a good agreement with the 8% error, thus validating the set of force field and the partial atomic charges used. Attachment energy method used by the simulation to predict the morphology of L-alanine crystal, revealed a prismatic crystal morphology bounded with 10 dominant faces: (110), ( 0), ( 10), (1 0), (020), (0 0) (011), (0 ), (0 1) and (01 ), which is in good agreement with the experimental morphology. Crystallization of L-alanine in the presence of glycine in the solution also resulted in prismatic crystal morphology, but elongated in the z-axis direction. This result was further explained by intermolecular bonding analysis of glycine on the morphological faces of L-alanine crystal, which suggested that glycine was preferentially adsorbed on the (0 ) and (1 0) faces of L-alanine crystal morphology.

Racemic Ibuprofen Morphology: Molecular Modelling and Experimental

Crystal morphology remains an important aspect in pharmaceutical industries and thus lengthy experimentally determined morphology becomes a routine. This leads to advancement of molecular modeling to assist in crystal morphology determination. Morphology of racemic ibuprofen can be grown in PEG 300 solvent and simulated via molecular modeling, the computational technique. The resulting morphology dictates its feasibility and prepares for further necessary control to produce desired morphology. Tuning up the morphology can be done by rationalizing out via molecular modeling the effect of the solvent and crystallization method. Solvent effect persists to influence crystal morphology mainly via interaction of hydrogen bond specific at different facets. However, the influence of solvent-surface interaction in enhancing or inhibiting crystal growth is still not completely resolved. To date, racemic ibuprofen grown in PEG 300 solvent is the first ever reported. The objective of this study is to compare experimental and predicted morphology of racemic ibuprofen using selected potential functions and charge set in vacuum condition. Racemic ibuprofen crystal morphology was grown in PEG 300 solvent via cooling at ambient temperature and predicted via attachment energy (AE) method using molecular modeling. It was found that the experimental morphology is tabular hexagonal while the predicted one is tabular octagonal. The facets were cleaved and its surface chemistry was explained. The predicted lattice energy with lowest percentage error of 0.02% is dominated by van der Waals force rather than electrostatic force.