Electronic and vibrational spectroscopic investigation of phenylacetylene-amine complexes. Evidence for the diversity in the intermolecular structures

Shifts in the electronic transitions for the complexes of phenylacetylene with ammonia, methylamine, and triethylamine clearly indicate the variation in the intermolecular structures of the three complexes. The infrared spectrum of phenylacetylene in the acetylenic C-H stretching region shows Fermi resonance bands, which act as a sensitive tool to probe the intermolecular structures. The IR-UV double resonance spectra of the three complexes are disparate and signify the formation of distinct structures. The formation of C-H...N hydrogen-bonded complex with ammonia and two distinct types of pi complexes with methylamine and triethylamine can be inferred from the analysis of electronic and vibrational spectra in combination with ab initio calculations. These complexes clearly point out the fact that marginal changes in the interacting partner can significantly alter the intermolecular structure.     

[2,3]-Wittig rearrangement approach to iminosugar C-glycosides: 5-epi-ethylfagomine, 2-epi-5-deoxyadenophorine and formal synthesis of indolizidine 167B and 209D

A new strategy for the synthesis of 1,2-dideoxy iminosugar C-glycosides and indolizidines involving highly stereoselective [2,3]-Wittig rearrangement from Garner aldehyde has been developed. This rearrangement yielded an optically pure, highly functionalized key intermediate, which has been further utilized for the synthesis of 5-epi-ethylfagomine, 2-epi-5-deoxyadenophorine, and 5-hydroxymethyl indolizidine.     

A π-stacked phenylacetylene dimer

The structure of the phenylacetylene-dimer has been elucidated using IR-UV double resonance spectroscopy in combination with high level ab initio calculations at the CCSD(T)/CBS level. The IR spectra in the acetylenic and the aromatic C-H stretching regions indicate that the two phenylacetylene moieties are in identical environments and very similar to the phenylacetylene monomer. Calculated stabilization energies and the free energies at the CCSD(T)/CBS level favor the formation of an anti-parallel π-stacked structure. The DFT-SAPT energy decomposition analysis points out that the anti-parallel π-stacked structure maximizes electrostatic as well as the dispersion components of energy. The observed IR spectra are consistent with the anti-parallel π-stacked structure.     

Synthesis of Tri‐functional Core‐shell CuO@carbon Quantum Dots@carbon Hollow Nanospheres Heterostructure for Non‐enzymatic H2O2 Sensing and Overall Water Splitting Applications

A core‐shell structure with CuO core and carbon quantum dots (CQDs) and carbon hollow nanospheres (CHNS) shell was prepared through facile in‐situ hydrothermal process. The composite was used for non‐enzymatic hydrogen peroxide sensing and electrochemical overall water splitting. The core‐shell structure was established from the transmission electron microscopy image analysis. Raman and UV‐Vis spectroscopy analysis confirmed the interaction between CuO and CQDs. The electrochemical studies showed the limit of detection and sensitivity of the prepared composite as 2.4 nM and 56.72 μA μM^?1 cm^?2, respectively. The core‐shell structure facilitated better charge transportation which in turn exhibited elevated electro‐catalysis towards hydrogen evolution reaction (HER), oxygen evolution reaction (OER) and overall water splitting. The overpotential of 159 mV was required to achieve 10 mA cm^?2 current density for HER and an overpotential of 322 mV was required to achieve 10 mA cm^?2 current density for OER in 1.0 M KOH. A two‐electrode system was constructed for overall water splitting reaction, which showed 10 and 50 mA cm^?2 current density at 1.83 and 1.96 V, respectively. The prepared CuO@CQDs@CHNS catalyst demonstrated excellent robustness in HER and OER catalyzing condition along with overall water splitting reaction. Therefore, the CuO@CQDs@CHNS could be considered as promising electro‐catalyst for H₂O₂ sensing, HER, OER and overall water splitting.     

Crystal structure of a furo-[3,2-g]-[1]-benzopyran-7-one derivative

The crystal structure of 9–(1,1-dimethyl–2-propenyl)-4-hydroxy-7H-Furo-[3,2-g]-benzopyran-7-one has been determined from X-ray diffraction data. The compound crystallizes in the monoclinic space group C2/c with unit cell parameters a = 8.976(3) Å, b = 16.621(2) Å, c = 17.818(2) Å, β = 95.79(2) Å. The gross structure was determined by direct methods and refined to a final value of R = 0.053. The three ring framework of the molecule is nearly planar. The side chain attached at the atomic position C(9) possesses significant foldings and has been found inclined to the ring system of the molecule.     

Crystal Structure of 7-Phenyl-5,6-Dihydro-14-Aza-[1]benzopyrano[3,4-b]phenanthren-8H-One

Crystallography Reports - The crystal structure of the title compound is determined by single crystal X-ray structure analysis. The crystals are monoclinic, space group P21/c, a = 13.607(3) Å,...     

(20R,22R)-6α,7α-Epoxy-5α,27-dihydroxy-1-oxowitha-2,24-dienolide in Leaves of Withania somnifera: Isolation and its Crystal Structure

Abstract  (20R,22R)-6α,7α-Epoxy-5α,27-dihydroxy-1-oxowitha-2,24-dienolide (27-hydroxy-withanolide B) was isolated from Withania somnifera. The structure of the withanolide was established by spectral analysis and X-ray diffraction studies. The compound crystallizes in the orthorhombic space group P2₁2₁2₁ with unit cell parameters: a = 9.2163(3), b = 11.1828(4), c = 23.6146(9) ?, Z = 4. The crystal structure was refined to R = 0.0495 for 3,284 observed reflections. All the rings of the steroid skeleton are trans connected. Rings A and B exist in a half-chair conformation, ring C a chair, and five membered ring D is intermediate between a half-chair and an envelope. The δ-lactone ring E adopts a distorted sofa conformation. The twist along the length of the steroid nucleus is −6.5°. The characteristic pattern observed in the packing diagram is the appearance of twisted chains of molecules packed together to form layers. Index Abstract  Isolation and crystal structure analysis of (20R,22R)-6α,7α-epoxy-5α,27-dihydroxy-1-oxowitha-2,24-dienolide.      

Bio-photonic detection method for morphological analysis of anthracnose disease and physiological disorders of Diospyros kaki

Optical Review - The pathological and physiological defects in various types of fruits lead to large amounts of economical waste. It is well recognized that internal fruit defects due to...     

Iodine-mediated new strategy for the synthesis of 2,5-disubstituted oxazoles from methyl ketones and TosMIC

A new strategy has been developed for the construction of oxazoles from methyl ketones and TosMIC via self-sorting oxidative domino reaction strategy. In contrast to its usual reactivity as C–N≡C synthon in the synthesis of oxazoles, TosMIC was utilized as ammonium surrogate in the present method. The protocol is attractive in terms of readily available starting materials, metal and base free conditions, operational simplicity, C–N and C–O bond formation. A variety of 2,5-disubstituted oxazoles were prepared in moderate-to-good yields.     

Unusual formation of novel highly substituted N-(3-indolyl)-imidazoles

Treatment of 3-amidoindoles with phosphoryl chloride leads to a dimerization of the resulting iminochlorides to form tetrasubstituted imidazoles in moderate yield. One indole ring undergoes ring-opening to allow the formation of the imidazole ring. This strategically simple synthesis considerably expands the scope of delivering N-indolylimidazoles.