Crystal structure, Hirshfeld surface analysis and HOMO-LUMO analysis of (E)-4-bromo-N'-(4-meth-oxy-benzyl-idene)benzohydrazide

Insights into glycosidic bond specificity of an engineered selective α-L-rhamnosidase N12-Rha via activity assays and molecular modelling

αL-rhamnosidase (EC 3.2.1.40) has been widely used in food processing and pharmaceutical preparation. The recombinant α-L-rhamnosidase N12-Rha from Aspergillus niger JMU-TS528 had significantly higher catalytic activity on α-1,6 glycosidic bond than α-1,2 glycosidic bond, and had no activity on α-1,3 glycosidic bond. The activities of hydrolyzed hesperidin and naringin were 7240 U/mL and 945 U/mL, respectively, which are 10.63 times that of native α-L-rhamnosidase. The activity could maintain more than 80% at pH 3–6 and 40–60℃. Quantum chemistry calculations showed that charge difference of the C-O atoms of the α-1,2, α-1,3 and α-1,6 bonds indicated that α-1,6 bond is most easily broken and α-1,3 bond is the most stable. Molecular dynamics simulations revealed that the key residue Trp359 that may affect substrate specificity and the main catalytic sites of N12-Rha are located in the (α/α)6-barrel domain.

Crystal structure, Hirshfeld surface analysis and HOMO-LUMO analysis of (E)-N'-(3-hy-droxy-4-meth-oxy-benzyl-idene)nicotinohydrazide monohydrate

The mol-ecule of the title Schiff base compound, C14H13N3O3·H2O, displays a trans configuration with respect to the C=N bond. The dihedral angle between the benzene and pyridine rings is 29.63 (7)°. The crystal structure features inter-molecular N-H⋯O, C-H⋯O, O-H⋯O and O-H⋯N hydrogen-bonding inter-actions, leading to the formation of a supramolecular framework. A Hirshfeld surface analysis indicates that the most important contributions to the crystal packing are from H⋯H (37.0%), O⋯H/H⋯O (23.7%)), C⋯H/H⋯C (17.6%) and N⋯H/H⋯N (11.9%) inter-actions. The title compound has also been characterized by frontier mol-ecular orbital analysis.

(E)-1-(Benzo[d][1,3]dioxol-5-yl)-3-([2,2'-bi-thio-phen]-5-yl)prop-2-en-1-one: crystal structure, UV-Vis analysis and theoretical studies of a new π-conjugated chalcone

In the title compound, C18H12O3S2, synthesized by the Claisen-Schmidt condensation method, the essentially planar chalcone unit adopts an s-cis configuration with respect to the carbonyl group within the ethyl-enic bridge. In the crystal, weak C-H⋯π inter-actions connect the mol-ecules into zigzag chains along the b-axis direction. The mol-ecular structure was optimized geometrically using Density Functional Theory (DFT) calculations at the B3LYP/6-311 G++(d,p) basis set level and compared with the experimental values. Mol-ecular orbital calculations providing electron-density plots of HOMO and LUMO mol-ecular orbitals and mol-ecular electrostatic potentials (MEP) were also computed both with the DFT/B3LYP/6-311 G++(d,p) basis set. The experimental energy gap is 3.18 eV, whereas the theoretical HOMO-LUMO energy gap value is 2.73 eV. Hirshfeld surface analysis was used to further investigate the weak inter-actions present.

Synthesis, X-ray crystal structure, Hirshfeld surface analysis and DFT studies of (E)-N'-(2-bromo-benzyl-idene)-4-methylbenzohydrazide

The title mol-ecule, C15H13BrN2O, displays a trans configuration with respect to the C=N double bond. The dihedral angle between the bromo- and methyl-substituted benzene rings is 16.1 (3)°. In the crystal, mol-ecules are connected by N-H⋯O and weak C-H⋯O hydrogen bonds, forming R 2 1(6) ring motifs and generating chains along the a-axis direction. The optimized structure generated theoretically via density functional theory (DFT) using standard B3LYP functional and 6-311 G(d,p) basis-set calculations renders good support to the experimental data. The HOMO-LUMO behaviour was elucidated to determine the energy gap. The inter-molecular inter-actions were qu-anti-fied and analysed using Hirshfeld surface analysis.