Weak C–H⋯O and C–H⋯π hydrogen bonds in crystal 1-indanone. An structural and spectroscopic analysis

Conformational analysis, molecular structure, spectroscopic, NBO, reactivity descriptors, wavefunction and molecular docking investigations of 5,6-dimethoxy-1-indanone: A potential anti Alzheimer's agent

The objective of the present study is focused to elucidate the structure of potential anti-Alzheimer's compound 5,6-Dimethoxy-1-indanone (5,6-DMI) and study its binding interaction towards the active site by molecular docking studies. The structural and various spectroscopic tools are used to understand the various interaction behaviors of the title compound. The theoretical calculation of 5,6-DMI molecule is computed by Gaussian 09W software with Density functional B3LYP and CAM-B3LYP method utilizing 6-311G(d,p) as basis set. The Natural Bond Orbital (NBO) analysis has been performed to find all possible transition was correlate with electronic transition. The Non covalent interaction of 5,6-DMI molecule was examined by adopt Reduced Density Gradient (RDG) analysis and colour filled ELF diagram. Molecular docking results suggest that 5,6-DMI may exhibit inhibitory activity against apoE protein and may act as potential against Alzheimer's disease.

Spectroscopic characterisation of centropolyindanes

A highly promising class of three-dimensional polyaromatic hydrocarbons comprises the centropolyindanes. The characteristic feature of these compounds is the mutual fusion of several molecules of indane along the saturated C-C bonds of their cyclopentane rings. Among the polycyclic aromatic hydrocarbons, the centropolyindanes are special because of the saturated core of sp3-hybridised carbon atoms embedded in a three-dimensional environment of aromatic building blocks. While the centropolyindanes and their numerous derivatives have been studied in detail by NMR spectroscopy, mass spectrometry and X-ray diffraction, investigation of their vibrational features, and especially those of the neopentane core present in most cases, have not been performed so far. In the present paper, we report the first systematic study of a set of centropolyindanes by vibrational spectroscopy, using inelastic neutron scattering (INS), infrared and Raman spectroscopies.

3-Ethylindan-1-one

The title compound, C11H12O, has been prepared as a side product in the attempted room-temperature synthesis of (E)-1-phenylpent-2-en-1-one. The molecular structure consists of an approximately planar indanone core (r.m.s. deviation = 0.042 Å) with the ethyl group protruding from this plane. In the crystal, centrosymmetrically related molecules are linked into dimers by pairs of C—H...O hydrogen bonds, forming rings ofR22(10) graph-set motif. The dimers are further connected by C—H...π interactions into chains running parallel to [-101].

Crystal structures of 6-chloro-indan-1-one and 6-bromo-indan-1-one exhibit different inter-molecular packing inter-actions

The two title compounds are analogs of 1-indanone that are substituted at the 6-position with chlorine and bromine. Although very similar in mol-ecular structure, the crystal structures are not isomorphous and reveal that 6-chloro-indan-1-one, C9H7ClO (I), and 6-bromo-indan-1-one, C9H7BrO (II), exhibit unique inter-molecular packing motifs. The mol-ecules of the chloro analog (I) pack with a herringbone packing motif of C-H⋯O inter-actions, whereas the bromo derivative (II) packs with offset face-to-face π-stacking, C-H⋯O, C-H⋯Br and Br⋯O inter-actions. Compound (II) was refined as a two-component non-merohedral twin, BASF 0.0762 (5).

6-Fluoro-indan-1-one

The title compound, C9H7FO, crystallizes with two independent mol-ecules in the asymmetric unit, in which corresponding bond lengths are the same within experimental error. The five-membered ring in each molecule is almost planar, with r.m.s. deviations of 0.016 and 0.029 Å. In the crystal, mol-ecules form sheets parallel to (1 0 0) via C-H⋯O and C-H⋯F inter-actions with F⋯F contacts [3.1788 (16) and 3.2490 (16) Å] between the sheets.

Application of the multi-parameter SQM harmonic force field, and ESFF harmonic frequencies scaling procedures to the determination of the vibrational spectra of silicon- and sulfur(II)-containing compounds

Multi-parameter scaling techniques, such as Scaled Quantum Mechanical (SQM) force field [J. Am. Chem. Soc. 105 (1983) 7037-7047; J. Phys. Chem. A 102 (1998) 1412-1424] or Effective Scaling Frequency Factor (ESFF) [Chem. Phys. Lett. 446 (2007) 191-198; J. Mol. Spectrosc. 264 (2010) 66-74] techniques, are very powerful in the theoretical prediction of the vibrational spectra of complex molecules. In the present work sets of transferable SQM and ESFF scaling factors (within the valence coordinates based schemes) that can be applied to silicon- and sulfur(II)-containing compounds have been determined. A number of VDZ- and VTZ-quality basis sets were used in conjunction with the B3LYP density functional. Eight molecules typically used in the synthesis of silica-based materials were chosen, and theoretical modes were assigned to bands detected on their IR or Raman spectra. This set was augmented with a set of 10 auxiliary, sulfur(II)-containing molecules, for which only "pure" vibrations involving S-containing motifs were assigned. This led to the set of more than 600 individual vibrations. Five factors attributed to these motifs were optimized. Scaling factors attributed to the characteristic types of internal coordinates including the second-row atoms and chlorine, which are applicable to the present molecules were preset. Their values, optimized for Baker's training set of molecules [J. Phys. Chem. A 102 (1998) 1412-1424] for all basis sets considered in this work, were also found, extending thus the applicability of the multi-parameter scaling methods. New scaling factors exhibit low statistical uncertainties. Reasonable agreement between experimental and SQM- or ESFF-scaled frequencies was obtained even for the 6-31G* basis set (RMS<12cm(-1)); extension of the basis set by adding polarization function on hydrogen atoms and/or diffuse functions provides significant improvement of the results, for which the RMS values are often (well) below 10 cm(-1). In addition, SQM scaling factors were found to occasionally exhibit large deviations from unity, which is to be contrasted with ESFF scaling factors.

Tautomeric Equilibria of [1]Benzopyrano[3,4-d]imidazol-4(3H)-ones, a Theoretical and NMR Study

[reaction: see text] Benzopyranoimidazolones could virtually exist in four tautomeric forms, namely N3-H, N1-H, coumarin O-H, and C2-H. Experimental evidence reported thus far has been unable to lead to a unique statement about the preferred tautomeric forms in solution. In this work, tautomeric equilibria for a series of 2-substituted [1]benzopyrano[3,4-d]imidazol-4(3H)-ones were investigated by DFT calculations, in both gas phase and solution. The influence of the solvent was included in the calculations by the CPCM solvent model. 13C chemical shifts of all tautomers were computed at different levels of theory and then compared with experiments to assign the preferred tautomers. Theoretical findings were then compared to dynamic 1H NMR experiments results.