Dichloridobis{N,N-diethyl-4-[(pyridin-2-yl-κN)diazen­yl]aniline}zinc

In the title complex, [ZnCl2(C15H18N4)2], the ZnII cation is coordinated by two N atoms from the pyridine rings of two unidentate N,N-diethyl-4-[(pyridin-2-yl)diazen­yl]aniline ligands and two Cl atoms, resulting in a distorted tetra­hedral geometry. The ligands are mutually transoid with respect to the metal atom. Weak inter­molecular C—H⋯Cl hydrogen bonds and π–π inter­actions, with centroid–centroid distances of 3.8452 (14) and 3.9932 (14) Å, are found in the crystal packing

OctaDist: a tool for calculating distortion parameters in spin crossover and coordination complexes

OctaDist is an interactive and visual program for determination of structural distortion in octahedral coordination complexes such as spin crossover complexes, single-ion magnets, perovskites or metal–organic frameworks. OctaDist computes the octahedral distortion parameters initially designed in the context of the spin-crossover phenomenon and denoted ζ, Σ, and Θ from standard structural files. The program also provides additional tools for molecular analyses and visualization. It emphasizes performance, flexibility, ease of use, application programming interface (API) consistency, and clear documentation. The modules and classes in OctaDist can be easily customized to include new algorithms or analytical tools. OctaDist is cross-platform supported for modern operating systems and is available as open-source distributed under the GNU General Public License version 3

Oligonucleotide Hybridization Combined with Competitive Antibody Binding for the Truncation of a High-Affinity Aptamer

Truncation can enhance the affinity of aptamers for their targets by limiting nonessential segments and therefore limiting the molecular degrees of freedom that must be overcome in the binding process. This study demonstrated a truncation protocol relying on competitive antibody binding and the hybridization of complementary oligonucleotides, using platelet derived growth factor BB (PDGF-BB) as the model target. On the basis of the immunoassay results, an initial long aptamer was truncated to a number of sequences with lengths of 36–40 nucleotides (nt). These sequences showed apparent <i>K</i>_D values in the picomolar range, with the best case being a 36-nt truncated aptamer with a 150-fold increase in affinity over the full-length aptamer. The observed binding energies correlated well with relative energies calculated by molecular dynamics simulations. The effect of the truncated aptamer on PDGF-BB-stimulated fibroblasts was found to be equivalent to that of the full-length aptamer