The Synthesis by Annelation of 1-Cyanochrysene

1-Cyanochrysene (I) has recently been prepared by photocyclisation of 1-(α-naphthyl)-2-cyanophenylethene.¹ In view of successful annelation reactions using 1,5-diazapentadienium perchlorate,² which are believed to involve a 6π-electrocyclic disrotatory ring closure,³ we attempted a synthesis of the chrysene (I), starting from 2-acetylphenanthrene.     

1,1′,1′′-(2,4,6-Trihydroxybenzene-1,3,5-triyl)triethanone tautomerism revisited

It has recently been suggested that 1,1′,1′′-(2,4,6-trihydroxybenzene-1,3,5-triyl)triethanone may be tautomeric. Using ¹³C NMR chemical shifts and deuterium isotope effects on ¹³C chemical shifts, it is demonstrated that this is not the case. This compound occurs as a strongly hydrogen bonded benzene structure with hydrogen bonds between OH groups and the acetyl groups in both non-polar and hydrogen donating solvents. Quantum-chemical calculations using MP2 and M06-2X methods show substantial preference for the phenol structure in both the gas phase, and in cyclohexane and methanol. In addition, conventional UV–vis spectroscopy data suggest not tautomeric, but aggregation behaviour of the molecule in methanol and acetonitrile.     

Friedel-crafts cyanation of some reactive aromatic hydrocarbons

Direct cyanation, using the heterogeneous Friedel-Crafts system cyanogen bromide/aluminium chloride, has given good yields of the following carbonitriles: anthracene-9-, chrysene-6-, 2-methyl-1-naphtho-, 4-methyl-1-naphtho-, 1-naphtho-, phenanthrene-9-, 2,4,6-trimethylbenzo-, triphenylene-1- and triphenylene-2-carbonitriles.     

An integrated approach to the study of the tautomerism of 4‐((Phenylimino)methyl) naphthalene‐1‐ol

The aim of the current report is to shed light on the tautomerism of 4‐((Phenylimino)methyl) naphthalene‐1‐ol in solution, which was studied by UV–Vis spectroscopy and quantum chemical calculations. It was found that this compound does not have the typical tautomeric behavior of its analog 4‐Phenylazo‐naphthalen‐1‐ol. The complicated equilibrium between the enol‐ and keto‐like forms and two kinds of dimers that can exist in solution, is strongly dependent on the proton acceptor/donor abilities of the solvent. Using advanced data treatment quantitative information about the tautomeric and dimeric equilibrium constants was obtained. Copyright © 2007 John Wiley & Sons, Ltd.     

Substitution and Solvent Effect of Some Substituted Hydroxy Schiff Bases

Abstract

The uv-vis spectra of eight ortho-hydroxy- andpara-hydroxy schiff bases were recorded in different solvents. Inductive and resonance effect of the substituents affect the electronic spectra of those molecules, while, intra-molecular hydrogen bond formation or breakage have little effect on the uv-visible spectra.     

1H and 13CNMR Study of a New Class of Bipyridinium Liquid Crystals

Abstract

¹H and ¹³C NMR, as well as UV and IR, spectra of a new class of bipyridinium salts made by double quaternization of trans?1, 2-bis(4-pyridyl) ethene unit with n-alkyl salts are reported. The effect of quaternization on the ¹ and ¹³C NMR spectra of the salts is discussed.     

Computational Prediction of 1H and 13C NMR Chemical Shifts for Protonated Alkylpyrroles: Electron Correlation and Not Solvation is the Salvation

Prediction of chemical shifts in organic cations is known to be a challenge. In this article we meet this challenge for α-protonated alkylpyrroles, a class of compounds not yet studied in this context, and present a combined experimental and theoretical study of the ¹³C and ¹H chemical shifts in three selected pyrroles. We have investigated the importance of the solvation model, basis set, and quantum chemical method with the goal of developing a simple computational protocol, which allows prediction of ¹³C and ¹H chemical shifts with sufficient accuracy for identifying such compounds in mixtures. We find that density functional theory with the B3LYP functional is not sufficient for reproducing all ¹³C chemical shifts, whereas already the simplest correlated wave function model, Møller–Plesset perturbation theory (MP2), leads to almost perfect agreement with the experimental data. Treatment of solvent effects generally improves the agreement with experiment to some extent and can in most cases be accomplished by a simple polarizable continuum model. The only exception is the NH proton, which requires inclusion of explicit solvent molecules in the calculation.     

Thioalkylated tetraethylene glycol: a new ligand for water soluble monolayer protected gold clusters

Ligand-stabilised, water-soluble gold nanoparticles of two different size ranges (2-4 and 5-8 nm) are readily prepared using monohydroxy (1-mercaptoundec-11-yl) tetraethylene glycol as a novel capping agent. These nanoparticles are as stable as alkylthiol-capped monolayer protected clusters (MPCs) and do not aggregate from aqueous solution under a wide range of stringent conditions. It is expected that this new material will be useful for a number of bio-analytical applications.