Triarylborane conjugated dicyanovinyl chromophores: intriguing optical properties and colorimetric anion discrimination. Issue 45 (28th October 2015)

• Record Type: Journal Article
• Authors: Kumar, George Rajendra; Sarkar, Samir Kumar; Thilagar, Pakkirisamy
• Is Part Of: Physical chemistry chemical physics. Volume 17:Issue 45(2015)
• Page Start: 30424
• Page End: 30432
• Publication Date: 2015-10-28
• Subjects: Chemistry, Physical and theoretical -- Periodicals; 541.3
• DOI: 10.1039/c5cp05378a
• Languages: English
• ISSNs: 1463-9076

Abstract

Abstract : Three new triarylborane conjugated dicyanovinyl chromophores (Mes2 B–π–donor–DCV) of type A–D–A are reported. All the compounds show intriguing dual fluorescence and two of them can be used for the naked-eye detection of F − and CN − ions. Abstract : Three new triarylborane conjugated dicyanovinyl chromophores (Mes2 B–π–donor–DCV); donor: N -methyldiphenylamine (1 ) and triphenylamine (2 and3 [with two BMes2 substitutions]) of type A–D–A (acceptor–donor–acceptor) are reported. Compounds1–3 exhibit intense charge transfer (CT) absorption bands in the visible region. These absorption peaks are combination CT bands of the amine donor to both the BMes2 and DCV units. This inference was supported by theoretical studies. Compound1 shows weak fluorescence compared to2 and3 . The discrimination of fluoride and cyanide ions is essential in the case of triarylborane (TAB) based anion sensors as a similar response is given towards both the anions. Anion binding studies of1, 2 and3 showed that fluoride ions bind selectively to the boron centre and block the corresponding CT transition (donor to BMes2 ) leaving the other CT transition to be red shifted. On the other hand, cyanide ions bind with both the receptor sites and stop both the CT transition processes and hence a different colorimetric response was noted. The binding of F − /CN − induces colour changes in the visible region of the electronic spectra of2 and3, which allows for the naked-eye detection of F − and CN − ions. The anion binding mechanisms are established using NMR titration experiments.