Self-Assembled Superstructure of Xanthene Derivatives

Various multi carbon homologations of 9-phenyl-9H-xanthen-9-ol (1) were obtained through a C-C bond formation by reacting it with various enolisable ketones in the presence of 1,1′-(ethane-1,2-diyl)dipyridinium bistribromide (EDPBT). All the ten derivatives along with the starting xanthen-9-ol have been characterized by single crystal X-ray diffraction. They all form self-assembled superstructure in the solid state. The self-assembling patterns in these supramolecular architectures were explained based on steric and electronic nature of the pendant arm. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Molecular structure,DFT studies,Hirshfeld surface analysis,energy frameworks,and molecular docking studies of novel (E)-1-(4-chlorophenyl)-5-methyl-N′-((3-methyl-5-phenoxy-1-phenyl-1H-pyrazol-4-yl) methylene)-1H-1, 2, 3-triazole-4-carbohydrazide

Abstract

The synthesis of the compound and its crystal structure having a monoclinic crystal system has been reported earlier. Optimized bond lengths and angles are showing good agreements with experimental data using DFT/B3LYP method. Energy of highest occupied molecular orbital and lowest unoccupied molecular orbital has been predicted to analyze the stabilities of compound. Crystal explorer 17.5 helps to visualize intermolecular interactions and its contributions to each interaction within molecule. The preeminence of dispersion energy component over the other components was established by interaction energy calculations and lattice energy framework analysis using same software. The molecular docking study was performed for molecule using AutoDock software.     

The CO2-water system. I. Study of the slower hydration-dehydration step

Using pressure-jump, concentration-jump, and stopped-flow methods, we have studied the rate of dehydration (k_–1) of carbonic acid as a function of temperature (0–40°C) and ionic strength (0.005–3M NaCl, 3M LiBr) in both H₂O and D₂O. A new design of pressure-jump cell with reliable temperature control, as well as improved sensitivity in the spectrophotometric detection for stopped flow, enabled k_–1 values to be determined with an accuracy better than ±8%, based on a comparison of results obtained using five different techniques. The influence of ionic strength, temperature, and isotope effects are discussed.     

Field determination of iodide in water

A simple, fast and sensitive spectrophotometric method for the quantification of iodine and iodide in waters is described. Firstly iodide has been oxidised by sodium nitrite to iodine in HCl medium and the resulting I₂Cl^– has been preconcentrated into toluene. This can be subsequently determined in the extract with brilliant green. A ten-fold preconcentration is obtained, the molar absorptivity is (4.2×10⁴) I mol^–1 cm^–1 at 635 nm. A detection limit of 4 ng/ml iodide in water can be reached. The effect of common anions and cations have been investigated. The method has been applied to the determination fo free iodine, total iodine and iodide in river, pond and well water.     

McLafferty-type rearrangement in the collision-induced dissociation of Li+, Na+ and Ag+ cationized esters of N-acetylated peptides

In this study we investigated the multi-stage collision-induced dissociation (CID) of N-terminally acetylated di-, tri- and tetrapeptides in the form of C-terminal ethyl, n-propyl, isopropyl, n-butyl and tert-butyl esters and cationized by the attachment of Li(+), Na(+) and Ag(+). While methyl ester versions of the metal cationized peptides primarily eliminate H(2)O following collisional activation and dissociation, the ethyl, propyl and butyl ester versions of the peptides exhibit a dissociation pathway consistent with gamma-hydrogen transfer to the C-terminal carbonyl group, with associated elimination of an alkene, in a McLafferty-type rearrangement. The rearrangement leaves a metal cationized, free-acid form of the peptide, as confirmed by comparing the multi-stage CID of rearrangement products generated from peptide esters with the CID of corresponding metal cationized free-acid peptides. The transfer of a gamma-hydrogen in the rearrangement reaction was confirmed by investigating the CID of ethyl esters for which the terminal methyl group was labeled with deuterium. We found that the rearrangement product was significantly more abundant, relative to other product ions, when derived from isopropyl and tert-butyl esters than from ethyl, n-propyl or n-butyl ester analogues.