No abstract

Hydrogen bonding can be used to significantly enforce the intra‐columnar stacking order in discotic mesogens. The ordered hexagonal columnar mesophase of a HAT‐CONHR derivative is characterized by the smallest inter‐disk distance ever found in columnar liquid crystals (3.18–3.20 Å). This additional attractive interaction between the disks in the column results in a regular disc stacking and thus in a high charge‐carrier mobility over the whole investigated temperature range (from room temperature up to 200 °C).

The high-resolution NMR solution structure of the catalytic fragment of human collagenase-3 (MMP-13) was used as a starting point for structure-based design of selective inhibitors for MMP-13. The major structural difference observed between the MMP structures is the relative size and shape of the S1′ pocket where this pocket is significantly longer for MMP-13, nearly reaching the surface of the protein. On the basis of the extended nature of the MMP-13 S1′ pocket an inhibitor potent and selective for MMP-13 was designed from an initial high throughput screening (HTS) lead. CL-82198 was identified as a weak (10 µM) inhibitor against MMP-13 while demonstrating no activity against MMP-1, MMP-9, or the related enzyme TACE. The drug-like properties of CL-82198 made it an ideal candidate for optimization of enzyme potency and selectivity. On the basis of NMR binding studies, it was shown that inhibitor CL-82198 bound within the entire S1′ pocket of MMP-13 which is the basis of its selectivity against MMP-1, MMP-9, and TACE. A strategy utilizing this information was devised for designing new inhibitors that showed enhanced selectivity toward MMP-13. Our design strategy combined the critical selectivity features of CL-82198 with the known potency features of a nonspecific MMP inhibitor (WAY-152177) to generate a potent and selective MMP-13 inhibitor (WAY-170523). WAY-170523 has an IC50 of 17 nM for MMP-13 and showed >5800-, 56-, and >500-fold selectivity against MMP-1, MMP-9, and TACE, respectively.A structure-based approach to designing potent and selective inhibitors has established itself as an important component of the drug development process (for reviews see refs 1 and 2). This is evident by the extensive structural data available for the matrix metalloproteinase (MMP) family of enzymes and the emergence of unique inhibitors based on this structural information (for reviews see refs 3-7). The MMPs are involved in the degradation of the extracellular matrix that is associated with normal tissue remodeling processes such as pregnancy, wound healing, and angiogenesis. MMP expression and activity is highly controlled because of the degradative nature of these enzymes where the apparent loss in this regulation results in the pathological destruction of connective tissue and the ensuing disease state. Thus, the MMPs are a highly active set of targets for the design of therapeutic agents for the disease areas of arthritis and oncology. The MMP family is composed of a number of enzymes where MMP-13 was recently identified on the basis of differential expression in normal breast tissues and in breast carcinoma. Recently, both an NMR and X-ray structure of inhibited MMP-13 have been reported. 8,9 The MMPs are generally categorized based on their substrate specificity, where the collagenase subfamily of MMP-1, MMP-8, and MMP-13 selectively cleaves native interstitial collagens (types I, II, and III). It is likely that only a subset of MMP enzymes will be involved in a particular disease as is evident by the overexpression o...

A concept for highly ordered solid-state structures with bright fluorescence is proposed:  liquid crystals based on tetraethynylpyrene chromophores, where the rigid core is functionalized with flexible, promesogenic alkoxy chains. The synthesis of this novel material is presented. The thermotropic properties are studied by means of differential scanning calorimetry (DSC), cross-polarized optical microscopy (POM), and X-ray diffraction. The mesogen possesses an enantiotropic Colh phase over a large temperature range before clearing. The material is highly fluorescent in solution and, most remarkably, in the condensed state, with a broad, strongly red shifted emission. Fluorescence quantum yields (ΦF) have been determined to be 70% in dichloromethane solution and 62% in the solid state. Concentration- and temperature-dependent absorption and emission studies as well as quantum-chemical calculations on isolated molecules and dimers are used to clarify the type of intermolecular interactions present as well as their influence on the fluorescence quantum yield and spectral properties of the material. The high luminescence efficiency in the solid state is ascribed to rotated chromophores, leading to an optically allowed lowest optical transition.