TY - JOUR A1 - Gnutzmann, Tanja A1 - Rademann, K. A1 - Emmerling, Franziska T1 - Fast crystallization of organic glass formers N2 - An unusually fast crystallization of the organic glass former nifedipine has been observed. The crystallization process, starting from an amorphous film to crystalline material, was investigated by time resolved Raman microspectroscopy. The crystallization rates of the initially crystallizing metastable β-form are four orders of magnitude higher than those of previous studies. KW - Polymorphism KW - Raman spectroscopy KW - Crystallization KW - Nifedipine PY - 2012 DO - https://doi.org/10.1039/c1cc16301a SN - 0022-4936 SN - 0009-241x SN - 1359-7345 SN - 1364-548x VL - 48 SP - 1638 EP - 1640 PB - Royal Society of Chemistry CY - Cambridge AN - OPUS4-27735 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gnutzmann, Tanja T1 - Fast crystallization of organic glass form T2 - SPP 1415 Symposium "Kristalline Nichtgleichgewichtsphasen - Theorie und Experiment" CY - Darmstadt, Germany DA - 2012-09-19 PY - 2012 AN - OPUS4-26928 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gnutzmann, Tanja T1 - Crystallization studies utilzing levitated droplets T2 - Fourth Joint BER II and BESSY Users Meeting CY - Berlin, Germany DA - 2012-12-12 PY - 2012 N1 - Geburtsname von Batzdorf, Lisa: Tröbs, L. - Birth name of Batzdorf, Lisa: Tröbs, L. AN - OPUS4-27486 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gnutzmann, Tanja A1 - Kahlau, R. A1 - Scheifler, S. A1 - Friedrichs, Ferdinand A1 - Rössler, A. A1 - Rademann, Klaus A1 - Emmerling, Franziska T1 - Crystal growth rates and molecular dynamics of nifedipine N2 - The unusually fast crystallization of the organic compound nifedipine has been investigated in detail using different solutions as precursors for the formation of the initial glassy nifedipine films. Starting from these amorphous films the crystallization process was investigated by time-resolved light microscopy at different temperatures around Tg of nifedipine. In all studied cases (acetone, acetonitrile, ethyl acetate, dichloromethane, tetrahydrofuran) the measured mean crystallization rates are, on average, 10000 times higher than rates reported in previous studies. Such high rates cannot be explained by a classical diffusional crystal growth mechanism of nifedipine. Instead, nifedipine shows a strong propensity for diffusionless growth. Solvent assisted or solvent induced preordering of the glassy modification is suggested to be the most probable driving force behind these fast crystallization processes. The nifedipine crystallization rates can be controlled not only by specific solvent–molecule interactions but also by temperature. Below 40 °C, the temperature dependence of the rates is generally small. Above 40 °C, a slowing down of the crystallization rates with increasing temperatures indicates a kinetic competition between different polymorphs. The molecular dynamics of nifedipine molecules in the amorphous phase as well as the relaxation times are studied by dielectric measurements. The dielectric data corroborate the inherently strong propensity of nifedipine to crystallize diffusionlessly under all conditions. KW - Fast crystallization KW - Diffusionless growth KW - Polymorphism KW - Nifedipine KW - Preordering KW - Raman spectroscopy KW - Dielectric spectroscopy PY - 2013 DO - https://doi.org/10.1039/c2ce26911b SN - 1466-8033 VL - 15 IS - 20 SP - 4017 EP - 4202 CY - London, UK AN - OPUS4-28307 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gnutzmann, Tanja T1 - Time-resolved investigation of crystallization processes T2 - SMI Symposium CY - Bochum, Germany DA - 2012-03-26 PY - 2012 AN - OPUS4-25677 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gnutzmann, Tanja T1 - In situ characterization of crystallization processes applying synchrotron XRD and Raman spectroscopy T2 - International School of Crystallography - 44th Course The Power of Powder Diffraction CY - Erice, Italy DA - 2011-06-02 PY - 2011 AN - OPUS4-23976 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -