Study of the correlations of the MLCT Vis absorption maxima of 4-pentacyanoferrate-4 '-arylsubstituted bispyridinium complexes with the Hammett substituent parameters and the solvent polarity parameters E-T(N) and AN

Papadakis, R; Tsolomitis, A

dc.contributor.author	Papadakis, R	en
dc.contributor.author	Tsolomitis, A	en
dc.date.accessioned	2014-03-01T01:58:59Z
dc.date.available	2014-03-01T01:58:59Z
dc.date.issued	2009	en
dc.identifier.issn	0894-3230	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/28806
dc.subject	pentacyanoferrate complex salts	en
dc.subject	substituent effects	en
dc.subject	solvatochromism	en
dc.subject	Hammett equation	en
dc.subject	LFERs	en
dc.subject.classification	Chemistry, Organic	en
dc.subject.classification	Chemistry, Physical	en
dc.subject.other	RUTHENIUM(II)	en
dc.subject.other	SPECTRA	en
dc.subject.other	SALTS	en
dc.title	Study of the correlations of the MLCT Vis absorption maxima of 4-pentacyanoferrate-4 '-arylsubstituted bispyridinium complexes with the Hammett substituent parameters and the solvent polarity parameters E-T(N) and AN	en
heal.type	journalArticle	en
heal.language	English	en
heal.publicationDate	2009	en
heal.abstract	In this work six new 4-aryl substituted bispyridinium salts have been synthesized using 2,4-dinitrophenyl-bispyridinium chloride as the starting material, which was arenamine exchanged via the Zincke reaction. These aromatic heterocyclic salts were used as ligands, acting as Lewis bases to form a series of 4-pentacyanoferrate-4'-aryl substituted bispyridinium complex salts in high yields. The complex salts were characterized using several spectroscopic techniques including H-1 as well as C-13 NMR spectroscopy, UV-Vis and FTIR spectrophotometry. These materials present a number of interesting electronic and optical properties. Herein we mainly focused on the electronic absorption of these materials. The visible metal-to-ligand-charge-transfer (MLCT) band of these materials assigned as d pi(Fe-II) -> pi*(L) was proved to be affected by substituent changes (of the benzene ring of the complexes) but mainly by solvent polarity changes. Band shifts of even 4000 cm(-1) were induced by small solvent polarity changes (e.g., water to methanol). The Vis absorption spectra were investigated in four protic solvents (water, 2,2,2-trifluoroethanol, ethylene glycol, and methanol). The substituent effects were then quantified using the Hammett equation which correlates the MLCT absorption wavenumbers with the Hammett constant (sigma(x)). Furthermore, two of the most successful solvent polarity parameters (the acceptor number AN and the normalized solvent polarity scale E-T(N)) were used to quantify the solvent polarity effects on the MLCT absorption wavenumbers. The correlations obtained in all cases proved to be satisfactory. The dominant interaction responsible for the solvent polarity effects proved to be the hydrogen-bond formation between the cyano groups of the complex salts and the protic solvents. Copyright (C) 2009 John Wiley & Sons, Ltd.	en
heal.publisher	JOHN WILEY & SONS LTD	en
heal.journalName	JOURNAL OF PHYSICAL ORGANIC CHEMISTRY	en
dc.identifier.isi	ISI:000265744900024	en
dc.identifier.volume	22	en
dc.identifier.issue	5	en
dc.identifier.spage	515	en
dc.identifier.epage	521	en