Controlling the Structure and Morphology of Organic Nanofilaments Using External Stimuli.

In our continuing pursuit to generate, understand, and control the morphology of organic nanofilaments formed by molecules with a bent molecular shape, we here report on two bent-core molecules specifically designed to permit a phase or morphology change upon exposure to an applied electric field or irradiation with UV light. To trigger a response to an applied electric field, conformationally rigid chiral (S,S)-2,3-difluorooctyloxy side chains were introduced, and to cause a response to UV light, an azobenzene core was incorporated into one of the arms of the rigid bent core. The phase behavior as well as structure and morphology of the formed phases and nanofilaments were analyzed using differential scanning calorimetry, cross-polarized optical microscopy, circular dichroism spectropolarimetry, scanning and transmission electron microscopy, UV-vis spectrophotometry, as well as X-ray diffraction experiments. Both bent-core molecules were characterized by the coexistence of two nanoscale morphologies, specifically helical nanofilaments (HNFs) and layered nanocylinders, prior to exposure to an external stimulus and independent of the cooling rate from the isotropic liquid. The application of an electric field triggers the disappearance of crystalline nanofilaments and instead leads to the formation of a tilted smectic liquid crystal phase for the material featuring chiral difluorinated side chains, whereas irradiation with UV light results in the disappearance of the nanocylinders and the sole formation of HNFs for the azobenzene-containing material. Combined results of this experimental study reveal that in addition to controlling the rate of cooling, applied electric fields and UV irradiation can be used to expand the toolkit for structural and morphological control of suitably designed bent-core molecule-based structures at the nanoscale.

A novel imidazole-based azo molecule: synthesis, characterization, quantum chemical calculations, molecular docking, molecular dynamics simulations and ADMET properties.

CONTEXT: Today, the treatment or prevention of cancer, which is one of the most important causes of death, has a very important place. On the other hand, the discovery of new antimicrobial agents is also important because of antibiotic resistance that can occur in humans. For these reasons, in this study, the synthesis, quantum chemical calculations, and in silico studies of a novel azo molecule with high bioactive potential were carried out. In the first step of the synthesis part, (3-(4-methyl-1H-imidazol-1-yl)-5-(trifluoromethyl)aniline compound, which is the raw material of the drug used in cancer treatments, was synthesized. In the second step, a novel product 2-hydroxy-5-((3-(4-methyl-1H-imidazol-1-yl)-5-trifluoromethyl)phenyl)diazenyl)benzaldehyde (HTB) was obtained as a result of the reaction of salicylaldehyde coupling to this compound. Then, as it was being spectroscopically described, its geometry was optimized. In order to perform quantum chemical calculations, the molecular structure, vibrational spectroscopic data, electronic transition absorption wavelengths, HOMO and LUMO analyses, molecular electrostatic potential (MEP) and potential energy surface (PES) of the molecule were all taken into consideration. Using molecular docking simulations, in silico interactions of the HTB molecule with some anticancer and antibacterial-related proteins were studied. In addition, the ADMET parameters of the HTB were also predicted. METHODS: The structure of the synthesized compound was elucidated using 1H-NMR, 13C-NMR (APT), 19F-NMR, FT-IR and UV-vis spectroscopic methods. The optimized geometry, molecular electrostatic potential diagram and vibrational frequencies of the HTB molecule were calculated at the DFT/B3LYP/6-311G(d,p) level. The TD-DFT method was used to calculate HOMOs-LUMOs and electronic transitions, and the GIAO method was used to calculate chemical shift values. It was observed that the experimental spectral data were in good agreement with the theoretical ones. Molecular docking simulations of the HTB molecule using 4 different proteins were investigated. Two of these proteins were involved in simulating anticancer activity and the other two in simulating antibacterial activity. According to molecular docking studies, the binding energies of the complexes formed by the HTB compound with the 4 selected proteins were between -9.6 and -8.7 kcal/mol. HTB showed the best affinity with VEGFR2 protein (PDB ID: 2XIR) and the binding energy of this interaction was found to be -9.6 kcal/mol. The HTB-2XIR interaction was examined with molecular dynamics simulation for 25 ns and it was determined that this complex was stable during this time. In addition, the ADMET parameters of the HTB were also calculated, and from these values, it was determined that the compound has very low toxicity and high oral bioavailability.

Comparative in vitro and DFT antioxidant studies of phenolic group substituted pyridine-based azo derivatives.

Two azo compounds 2-(3-pyridylazo)-3,5-dihydroxybenzoic acid (PAB) and 4-(3-pyridylazo)resorcinol (PAR) thought to have the potential to be used as antioxidants were designed, synthesized and antioxidant activities were investigated both in vitro and in silico. The synthesized compounds were characterized by 1H-NMR, 13C-NMR, FT-IR, UV-Vis and mass spectra. The molecular geometry and vibrational frequency calculations of the synthesized compounds in ground state were performed by the density functional theory (DFT) employing B3LYP level with the 6-311 G(d,p) basis set. The gauge independent atomic orbital (GIAO) method was used to determine the chemical shift values of 1H-NMR and 13C-NMR. HOMO-LUMO calculations were carried out by time-dependent DFT (TD-DFT) approach. Computational spectroscopic data of the synthesized compounds are fully compatible with experimental ones. The antioxidant activities of the PAB and PAR were investigated by using DPPH assay. It was determined that the PAB molecule showed better antioxidant activity than PAR and, butylated hydroxytoluene (BHT) which is the standard antioxidant. In addition, the thermodynamic stability parameters obtained with the help of DFT calculations were found to be quite compatible with the antioxidant capacity sequence derived from the DPPH assay. HighlightsTwo pyridine derivative azo compounds were synthesized and evaluated for its antioxidant activityMolecular geometry and spectroscopic properties of the molecules were calculatedin vitro and in silico antioxidant activities were investigated by DPPH free radical scavenging assayThe PAB molecule showed better antioxidant activity than BHTCommunicated by Ramaswamy H. Sarma.

Total Synthesis of Olivacine and Ellipticine via a Lactone Ring-Opening and Aromatization Cascade.

Effective preparation of olivacine and ellipticine via late-stage D-ring cyclization is described. Key features of the synthetic routes include trifluoroacetic acid-mediated formation of a lactone that is fused to a tetrahydrocarbazole derivative and its one-pot two-step ring opening and aromatization mediated by para-toluenesulfonic acid and palladium on carbon, respectively.

Investigation of electrorheological properties of biodegradable modified cellulose/corn oil suspensions.

Considerable scientific and industrial interest is currently being focused on a class of materials known as electrorheological (ER) fluids, which display remarkable rheological behaviour, being able to convert rapidly and repeatedly from a liquid to solid when an electric field (E) is applied or removed. In this study, biodegradable cellulose was modified and converted to their carboxyl salts. Modified cellulose is characterised by Fourier transform infrared (FTIR) spectroscopy, nuclear magnetic resonance (NMR) spectroscopy, energy dispersive spectroscopy (EDS), thermogravimetric analysis (TGA) and conductivity measurements. Suspensions of cellulose (C) and modified cellulose (MC) were prepared in insulated corn oil (CO). The effects of electric field strength, shear rate, shear stress, temperature, etc. of these suspensions onto ER activity were determined. Rheological measurements were carried out via a rotational rheometer with a high-voltage generator to investigate the effects of electric field strength and particle concentration on ER performance. The results show that the ER properties are enhanced by increasing the particle concentration and electric field strength. Also the cellulose-based ER fluids exhibit viscoelastic behaviour under an applied electric field due to the chain formation induced by electric polarization between particles.