1.Bisthienylethenes containing a benzothiadiazole unit as a bridge: photochromic performance dependence on substitution position.
Zhu W1, Meng X, Yang Y, Zhang Q, Xie Y, Tian H. Chemistry. 2010 Jan 18;16(3):899-906. doi: 10.1002/chem.200901855.
A conveniently synthesized photochromic compound, BTB-1, containing an unprecedented six-membered 2,1,3-benzothiadiazole unit as the center ethene bridge, possesses good photochromic performance, with a high cyclization quantum yield and moderate fatigue resistance in solution or an organogel system. The fluorescence of BTB-1 can be modulated by solvato- and photochromism. However, the analogue BTB-2, in which the dimethylthiophene substituents are relocated to the 5,6-positions of benzothiadiazole, does not show any detectable photochromism. To the best of our knowledge, this is the first example of six-membered bridge bisthienylethenes (BTEs) in which the photochromism can be controlled by the substitution position. The photochromism difference is elucidated by the analysis of resonance structure, the Woodward-Hoffmann rule, and theoretical calculations on the ground-state potential-energy surface. In a well-ordered single-crystal state, BTB-1 adopts a relatively rare parallel conformation, and forms an interesting two-dimensional structure due to the presence of multiple directional intermolecular interactions, including C--HN and C--HS hydrogen-bonding interactions, and pi-pi stacking interactions.
2.Synthesis and biological evaluation of optimized inhibitors of the mitotic kinesin Kif18A.
Braun J1, Möckel MM, Strittmatter T, Marx A, Groth U, Mayer TU. ACS Chem Biol. 2015 Feb 20;10(2):554-60. doi: 10.1021/cb500789h. Epub 2014 Nov 26.
The mitotic spindle, a highly dynamic structure composed of microtubules, mediates the segregation of the previously duplicated genome into the two nascent daughter cells. Errors in this process contribute to pathology including tumor formation. Key for the shape and function of the mitotic spindle are kinesins, molecular motor proteins that convert chemical energy into mechanical work. Due to their fast mode of action, small molecules are valuable tools to dissect the dynamic functions of kinesins during mitosis. In this study, we report the identification of optimized small molecule inhibitors of the mitotic kinesin Kif18A. Using BTB-1, the first identified Kif18A inhibitor, as a lead compound, we synthesized a collection of derivatives. We demonstrate that some of the synthesized derivatives potently inhibited the ATPase activity of Kif18A with a half maximal inhibitory concentration (IC50) value in the low micromolar range. In vitro analysis of a panel of Kif18A-related kinesins revealed that the two most potent compounds show improved selectivity compared to BTB-1.