Evaluation of Antimicrobial, Anticholinesterase Potential of Indole Derivatives and Unexpectedly Synthesized Novel Benzodiazine: Characterization, DFT and Hirshfeld Charge Analysis.

The pharmacological effectiveness of indoles, benzoxazepines and benzodiazepines initiated our synthesis of indole fused benoxazepine/benzodiazepine heterocycles, along with enhanced biological usefulness of the fused rings. Activated indoles 5, 6 and 7 were synthesized using modified Bischler indole synthesis rearrangement. Indole 5 was substituted with the trichloroacetyl group at the C7 position, yielding 8, exclusively due to the increased nucleophilic character of C7. When trichloroacylated indole 8 was treated with basified ethanol or excess amminia, indole acid 9 and amide 10 were yielded, respectively. Indole amide 10 was expected to give indole fused benoxazepine/benzodiazepine 11a/11b on treatment with alpha halo ester followed by a coupling agent, but when the reaction was tried, an unexpectedly rearranged novel product, 1,3-bezodiazine 12, was obtained. The synthetic compounds were screened for anticholinesterase and antibacterial potential; results showed all products to be very important candidates for both activities, and their potential can be explored further. In addition, 1,3-bezodiazine 12 was explored by DFT studies, Hirshfeld surface charge analysis and structural insight to obrain a good picture of the structure and reactivity of the products for the design of derivatised drugs from the novel compound.

Synthesis, Crystal Structure, DFT Calculations, Hirshfeld Surface Analysis and In Silico Drug-Target Profiling of (R)-2-(2-(1,3-Dioxoisoindolin-2-yl)propanamido)benzoic Acid Methyl Ester.

The work here reflects synthesis, DFT studies, Hirshfeld charge analysis and crystal data exploration of pharmacologically important (R)-2-(2-(1,3-dioxoisoindolin-2-yl)propanamido)benzoic acid methyl ester (5) to understand its properties for further chemical transformations. The methyl anthranilate (2) was produced by the esterification of anthranilic acid in an acidic medium. The phthaloyl-protected alanine (4) was rendered by the fusion of alanine with phthalic anhydride at 150 °C, followed by coupling with (2) furnished isoindole (5). The characterization of products was performed using IR, UV-Vis, NMR and MS. Single-crystal XRD also verified the structure of (5) in which N-H⋯O bonding stabilizes the molecular configuration of (5), resulting in the formation of S(6) hydrogen-bonded loop. The molecules of isoindole (5) are connected in the form of dimers, and the π⋯π stacking interaction between aromatic rings further stabilizes the crystal packing. DFT studies suggest that HOMO is over the substituted aromatic ring, the LUMO is present mainly over the indole side, and nucleophilic and electrophilic corners point out the reactivity of the product (5). In vitro and in silico analysis of (5) shows its potential as an antibacterial agent targeting DNA gyrase and Dihydroorotase from E. coli and tyrosyl-tRNA synthetase and DNA gyrase from Staphylococcus aureus.

Determination of the Absolute Configuration of Ballonigrin Lactone A Using Density Functional Theory Calculations.

We report the determination of the absolute configuration of a diterpenoid, namely, ballonigrin lactone A (BLA), by comparison of the computed optical rotations, [α]D, of its two diastereomers using density functional theory (DFT) calculations to the experimental [α]D value of +22.4. One of the diastereomers having configurations 4S, 5R, 6S, 10S, 15S was named "α-BLA," and the other one with configuration 4S, 5R, 6S, 10S, 15R was called "ß-BLA". Six conformers for each diastereomer (α-BLA and ß-BLA) of BLA were identified through their conformational analysis. [α]D values of these six conformations for each diastereomer were calculated using DFT at the mPW1PW91/6-311G(d,p)/SMDChloroform level of theory, leading to the conformationally averaged [α]D values of -96.8 for α-BLA and +65.1 for ß-BLA. Thus, it was found that the experimental [α]D value of +22.4 was of 4S, 5R, 6S, 10S, 15R, i.e., ß-BLA. Experimental and computed nuclear magnetic resonance (NMR) data were also compared, and this comparison was in accordance with the conclusion drawn from the comparison of [α]D values. Finally, the results were augmented with the calculation of the DP4 analysis, and the probability obtained also endorsed our earlier calculations.

Finding New Precursors for Light Harvesting Materials: A Computational Study of the Fluorescence Potential of Benzanthrone Dyes.

Benzanthrone dyes are organic luminophores with excellent optoelectronic properties. This computational investigation is based on density functional theory and aims to explore the photophysical behavior of some of the reported aminobenzanthrones in addition to many unreported dyes containing different electron-donating substituents. Significant changes in the dipole moment and the overall structure of the dyes upon solvation in ethanol have been observed. We find that intramolecular charge transfer is more pronounced in the solvent medium, which facilitates the emission to shift bathochromically. Intersystem crossing is predicted to be absent, which makes relaxation of the molecule to ground state more efficient by emitting in the visible region.

Main-group metal cyclophane complexes with high coordination numbers.

Density functional theory calculations using the PBE0-D3BJ hybrid functional have been employed to investigate the complexation of main-group metal-cations with [2.2.2]paracyclophane and deltaphane. Geometry optimization under symmetry constraints was performed to observe the mode of coordination that a metal-cation adopts when it resides inside the cyclophane cavity. Thermodynamic properties were investigated to note the trends of stability along a group of metals. To further investigate the bonding properties, Morokuma-Ziegler energy decomposition analysis, natural bond orbital analysis and Bader's analysis were employed. It was observed that most of the main-group metal complexes with cyclophanes prefer an η6η6η6 coordination mode where the metal-cation sits in the centre of the cyclophane cavity. There is an increased thermodynamic stability in [2.2.2]paracyclophane complexes compared to their deltaphane analogues while the reverse is true regarding the strength of coordination based on interaction energy.

Reactions of In-Zn bonds with organic azides: products that result from hetero- and homo-bimetallic behaviour.

The indyl anion, K[In(NONDipp)] (NONDipp = [O(SiMe2NDipp)2]2-, Dipp = 2,6-iPr2C6H3) reacts with group 12 compounds M(BDIR)Cl (M = Zn, Cd; BDI = [HC{C(Me)NR}2]-, R = 2,4,6-Me3C6H2 (Mes), Dipp) to afford the heterobimetallic compounds (NONDipp)In-M(BDIR) that contain the first In-Zn and In-Cd bonds. The reactivity of the In-Zn bonds towards organic azides, R'N3 (R' = Mes, Dipp, Ph) was investigated. (NONDipp)In-Zn(BDIMes) reduces MesN3via an isolable triazenide intermediate to generate the bridging imido compound, (NONDipp)In-(µ-NMes)-Zn(BDIMes). Similar reactivity is noted from early-late heterobimetallic complexes. Under the same conditions, PhN3 reacts to afford a product that contains a bridging tetraazenide ligand, which is formed from the formal (2 + 3)-cycloaddition of second azide to an indium-imido bond. However, increasing the bulk of the BDI-ligand in (NONDipp)In-Zn(BDIDipp) leads to reductive coupling of PhN3 to give the hexazene complex. This mode of reactivity is reminiscent of the reductive behaviour of homobimetallic compounds.