Single crystal X-ray structure determination and temperature-dependent structural studies of the smectogenic compound 7OS5.

Structural characteristics of solid and liquid crystalline phases of 7OS5 (4-n-pentylphenyl-4'-n-heptyloxythiobenzoate), the achiral smectogenic mesogen with the shortest terminal carbon chain in the nOS5 homologous series, are studied by complementary methods. Simultaneously perfomed X-ray diffraction and differential scanning calorimetry occur to be a powerful tool to study metastable phases. The single crystal structure of a high-temperature phase, supercooled from the room temperature down to -183°C [orthorhombic crystal system; space group Pca21; a = 54.285 (5) Å, b = 5.5843 (3) Å, c = 14.841 (1) Å, Z = 8] is determined. Lamellar ordering of elongated molecules is stabilized by hydrogen bonds . Temperature dependence of unit-cell parameters in two crystal phases as well as structural parameters of liquid crystalline phases (smectic layer spacing, tilt angle, average distance between the long axes of molecules and correlation lengths) are determined by X-ray diffraction. The obtained results are compared with the data available for other compounds in the nOS5 homologous series.

Vibrational Dynamics of Carbamazepine: Studies Based on Two-Dimensional Correlation Spectroscopy and X-ray Diffraction.

Fourier transform infrared spectroscopy as well as X-ray diffraction (XRD) were employed to thoroughly study phase transitions taking place during heating-cooling-heating cycle of carbamazepine (CBZ), a well known and commonly used antiepileptic drug. Both techniques revealed cold crystallization taking place during second heating. Moreover, XRD studies for the first time proved the coexistence of CBZ (form I) and iminostilbene (product of the degradation of CBZ) after a heating-cooling cycle. Moving window two-dimensional correlation (MW 2D-COS) spectroscopy and two-dimensional correlation spectroscopy were shown to be effective tools to reveal phase sequences and to provide information about the order of sequential changes of bands' intensities during each phase transition, respectively.

Orientation and biorecognition of immunoglobulin adsorbed on spin-cast poly(3-alkylthiophenes): Impact of polymer film crystallinity.

Many of bioelectronic and biosensor applications are based on poly(3-alkylthiophenes), conducting and solution-processable polymers. The most facile approach for the fabrication of such devices relies on biofunctionalization of P3AT surfaces with antibodies through adsorption. The success of this approach depends critically on antibody orientation that affects its biorecognition. As demonstrated here both these features are controlled by the surface structure of spin-cast P3ATs. In particular, a multi-technique and multivariate study that involved Atomic Force Microscopy, Grazing Incidence X-ray Diffraction, Angle-Resolved X-ray Photoelectron Spectroscopy, Enzyme-Linked ImmunoSorbent Assay, and Time-of-Flight Secondary Ion Mass Spectrometry combined with Principal Component Analysis is conducted in order to deduce the crystalline texture of three P3AT polymers as well as its effect on orientation of adsorbed rabbit immunoglobulin (IgG) molecules. An edge-on crystalline texture is concluded for regioregular poly(3-butylthiophene) (RP3BT) and poly(3-hexylthiophene) (RP3HT), while amorphous morphology is inferred for poly(3-butylthiophene) (P3BT). In addition, end-on and head-on orientations similar for all P3ATs were concluded, based on the amount of adsorbed rabbit IgG molecules. Examination of amino acids characteristic for F(ab')2 and Fc fragments, and dominant in the external regions of adsorbed immunoglobulin molecules, points to end-on IgG alignment on RP3BT and RP3HT, but not on P3BT. Moreover, the binding of an anti-rabbit IgG antibody on the absorbed rabbit IgG is higher (up to 71%) when the biorecognition reactions are performed on regioregular rather than regiorandom P3AT surfaces. In particular, the highest biorecognition efficiency and IgG orientational order is observed for the RP3BT surfaces with the more developed crystallinity.