Structural Analogy Method in Studies of Adamantanes

Journal of Molecular Structure, 2018

A detailed structural analysis of two adamantane derivatives namely, ethyl 2-[(Z)-1-(adamantan-1-yl)-3-(phenyl)isothioureido]acetate I and ethyl 2-[(Z)-1-(adamantan-1-yl)-3-(4fluorophenyl)isothioureido]acetate II is carried out to understand the effect of fluorine substitution. The introduction of fluorine atom alters the crystal packing and is completely different from its parent compound. The fluorine substitution drastically reduced the intermolecular H•••H contacts and this reduction is compensated by intermolecular F•••H and F•••F contacts. The relative contributions of various intermolecular contacts present in these structures were quantified using Hirshfeld surface analysis. Energetically significant molecular pairs were identified from the crystal structures of these compounds using PIXEL method. The structures of I and II are optimized in gas and solvent phases using the B3LYP-D3/6-311++G(d,p) level of theory. The quantum theory of atoms-in-molecules (QTAIM) analysis was carried out to estimate the strengths of various intermolecular contacts present in these molecular dimers. The results suggest that the H-H bonding take part in the stabilization of crystal structures. The experimental and theoretical UV-Vis results show the variations in HOMO and LUMO energy levels. In silico docking analysis indicates that both compounds I M

Molecules, 2015

Adamantyl-based compounds are commercially important in the treatments for neurological conditions and type-2 diabetes, aside from their anti-viral abilities. Their values in drug design are chronicled as multi-dimensional. In the present study, a series of 2-(adamantan-1-yl)-2-oxoethyl benzoates, 2(a-q), and 2-(adamantan-1-yl)-2-oxoethyl 2-pyridinecarboxylate, 2r, were synthesized by reacting 1-adamantyl bromomethyl ketone with various carboxylic acids using potassium carbonate in dimethylformamide medium at room temperature. Three-dimensional structures studied using X-ray diffraction suggest

Journal of Physical Chemistry B, 2014

The polymorphism of two 2 X adamantane derivatives, X = Cl, X = Br, has been studied by X ray powder diffraction and normal and high pressure (up to 300 MPa) differential scanning calorimetry. 2 Br adamantane displays a low temperature orthorhombic phase (space group P2 1 2 1 2 1 , Z = 4) and a high temperature plastic phase (Fm3m, Z = 4) from 277.9 ± 1.0 K to the melting point at 413.4 ± 1.0 K. 2 Cl adamantane presents a richer polymorphic behavior through the temperature range studied. At low temperature it displays a triclinic phase (P1, Z = 2), which transforms to a monoclinic phase (C2/c, Z = 8) at 224.4 ± 1.0 K, both phases being ordered. Two high temperature orientationally disordered are found for this compound, one hexagonal (P6 3 /mcm, Z =6)at ca. 241 K and the highest one, cubic (Fm3m, Z = 4), being stable from 244 ± 1.0 K up to the melting point at 467.5 ± 1.0 K. No additional phase appears due to the increase in pressure within the studied range. The intermolecular interactions are found to be weak, especially for the 2 Br adamantane compound for which the Br•••Br as well as C−Br•••H distances are larger than the addition of the van der Waals radii, thus confirming the availability of this compound for building up diamondoid blocks.

Journal of Mathematics

In quantitative structure-property and structure-activity relationships studies, several graph invariants, namely, topological indices have been defined and studied due to their numerous applications in computer networks, biotechnology, and nanochemistry. Topological indices are numeric parameters that describe the biological, physical, and chemical properties depending on the structure and topology of different chemical compounds. In this article, we inaugurated some degree-based novel indices, namely, geometric-harmonic GHI , harmonic-geometric HGI , neighborhood harmonic-geometric NHGI , and neighborhood geometric-harmonic NGHI indices and verified their chemical applicability. Furthermore, an attempt is made to calculate analytical closed formulas for different variants of silicon carbides and analyze the obtained results graphically.

2001

Substituent effects are widely used to investigate the factors affecting carbon-13 chemical shifts. Among the most important of these are the steric effects used in structure determination. Recent investigations have shown that they may originate from carbon±hydrogen bond polarization or geometric factors such as bond distances, angles and dihedral angles.

Journal of The Brazilian Chemical Society, 2008

The relative stability of the 1,3-dehydro-5,7-adamantanediyl dication is ascribed to its tridimensional aromaticity. However, its electronic nature is not well known. In order to improve its understanding, dicationic and monocationic adamantanedyil species and some key analogues were studied by atoms in molecules (AIM) theory. They were compared to non-aromatic adamantane analogues. AIM results indicate that the density in center of the cage structure and the average of all delocalization indexes involving its bridged atoms are higher in aromatic than in non-aromatic compounds. Degeneracy in energy of the bridged atoms, uniformity and magnitude of their shared charge distinguish the dications 1,3-adamantyl and the 1,3-dehydro-5,7-adamantanediyl. However, both are aromatic as well as the 1,3-dehydro-5,7-diboroadamantane. The 1,3-dehydro-7-adamantyl cation has a characteristic planar homoaromaticity.

European Journal of Organic Chemistry, 2005

We present an iterative technique in which model checking and static analysis are combined to verify large software systems. The role of the static analysis is to compute partial order information which the model checker uses to reduce the state space. During exploration, the model checker also computes aliasing information that it gives to the static analyzer which can then refine its analysis. The result of this refined analysis is then fed back to the model checker which updates its partial order reduction. At each step of this iterative process, the static analysis computes optimistic information which results in an unsafe reduction of the state space. However, we show that the process converges to a fixed point at which time the partial order information is safe and the whole state space is explored.

Journal of Physical Organic Chemistry, 2013

The set of 42 diastereomeric structures resulting from various degrees of substitution of secondary-CH 2groups by amines-NHwithin the adamantane skeleton are investigated. They are placed into a substitution-reaction network viewed as a partial ordering, and the resultant reaction network (or Hasse diagram) displayed to illustrate different features. Ground-state ab-initio total energies of the 42 species are computed. A systematic cluster expansion of these total energies and associated internal energies is described in the context of this partial ordering. The results given support the idea, that recognition of the partial ordering is worthwhile.

Journal of chemical …, 1999

Adamantan-1-ammonium 1-adamantanecarboxylate, C 21 H 33 NO 2 (I) is a novel dispiro-type compound. Aminoadamantane derivatives, in which the spiro carbon atoms are part of heterocyclic rings, are of potential interest as biological active substances and antiviral agents. Complex (I) crystallizes in the centrosymmetric space group C2/c (No. 15) with eight molecules in the unit cell with a ϭ 25.227(4), b ϭ 6.527(1), c ϭ 22.489(4) Å , and ͱ ϭ 90.75(1)Њ. The two spiro units are a 1-adamantylammonium cation and a 1-adamantane carbonyloxy anion. The complex units are stabilized by a network of intermolecular carbonyloxy-to-amine hydrogen bonding and van der Waals cohesive forces. Germane bond lengths are: CUN ϭ 1.479(9) and CuO (mean) ϭ 1.25(2) Å .

Russian Journal of Applied Chemistry, 2006

The chromatographic behavior of adamantane derivatives as sorbates and sorbents was studied. The retention characteristics of adamantane derivatives and some organic compounds on an adamantylsilicone stationary phase were determined. The effect of various substituents on the chromatographic behavior of the compounds was examined. Correlations between the sorption and structural characteristics of adamantane derivatives were found.