The Effect of Extended π-Conjugation on the Spectroscopic and Electrochemical Properties of Boron Difluoride Formazanate Complexes

Authors

Stephanie M. Barbon
Viktor N. Staroverov
Joe GilroyFollow

Document Type

Article

Publication Date

Spring 5-6-2015

Journal

Journal of Organic Chemistry

Volume

80

First Page

5226

Last Page

5235

URL with Digital Object Identifier

DOI: 10.1021/acs.joc.5b00620

Abstract

The effect of extended π-conjugation on the spectroscopic and electrochemical properties of boron difluoride (BF₂) formazanate complexes was studied by the systematic comparison of phenyl- and naphthyl-substituted derivatives. Each of the BF₂ complexes described was characterized by ¹H, ¹³C, ¹¹B and ¹⁹F NMR spectroscopy, cyclic voltammetry, infrared spectroscopy, UV-vis absorption and emission spectroscopy and mass spectrometry. X-ray crystallography and electronic structure calculations were used to rationalize the trends observed, including direct comparison of 3-cyano-, 3-nitro- and 3-phenyl-substituted BF₂ formazanate complexes. In all cases, the wavelength of maximum absorption and emission were red-shifted as π-conjugation was systematically extended (by replacing phenyl with naphthyl), fluorescence quantum yields increased (up to tenfold) and electrochemical conversion of the formazanate complexes to their radical anion and dianion forms occurred at less negative potentials (easier to reduce).