Synthesis, molecular structure, spectroscopic investigations and computational study of a potential molecular switch of 2-([1,1’-biphenyl]-4-yl)-2-methyl-6-(4-nitrophenyl)-4-phenyl-1,3 diazabicyclo [3.1.0]hex-3-ene

The synthesis and spectroscopic characterization of (+)-demethoxyaspidospermine: Density functional theory calculations of the structural, electronic, and non-linear optic and spectroscopic properties

(+)-Demethoxyaspidospermine was synthesized via the acylation of aspidospermidine with acetic anhydride, and the structure was determined by elemental analysis and Fourier-transform infrared and nuclear magnetic resonance spectroscopic tools and was supported by the simulated spectroscopic studies. Next, the stable geometries obtained by the conformational analysis performed at the B3LYP/6-31G(d, p) level were used for further investigations carried out in B3LYP and M06-2X functionals, and Hartree–Fock (HF) method, employed by the 6-311++G(d, p) basis set. Also, the natural bond orbital analysis revealed that the most contribution to the lowering of the stabilization energy came from n → π* and π → π* interactions. Moreover, the non-linear optic analysis has shown that the title compound can be a useful agent in the optoelectronic devices because of the optical properties. Also, the chemical reactivity tendency for nucleophilic or electrophilic attack reactions on the compound was evaluated by frontier molecular orbital analysis, and the reactive sites of the compound was shown by highest molecular orbital and lowest unoccupied orbital amplitudes and molecular electrostatic potential diagrams.

Photoconversion of an anthraquinone derivative in the presence of human serum albumin

Photconversion of an anthraquinone photochrome (AQP) from Trans to Ana forms were studied by different methods and techniques. Solution of AQP was irradiated under UV light in buffer condition, pH = 7.5, 10 mM phosphate buffer in the absence and presence of human serum albumin at 27 and 37 °C. The results showed that a new peak at higher wavelength was observed that indicative of producing the Ana form. Rate of Trans to Ana conversion increases in the presence of human serum albumin (HSA). Electron transport calculations were carried out from the first principles with a method based on non-equilibrium Green's functions (NEGF) combined with DFT. The results showed that electron transport is easier in Ana form due to increasing the resonance length and electron delocalization. Binding study by docking and spectroscopy showed that Trans form has more tendency to interact with HSA due to higher number of HSA-Trans hydrogen bond. Structural studies by circular dichroism and molecular dynamics results show that at lower concentration of AQP, percentage of helix was increased and then decreases at higher concentration. In addition structural parameters such as RMSD, accessible surface area, hydrogen bond, in associated with experimental results showed that protein folded at low concentration.