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Updated: Mar 31, 2026

Qualitative Identification of Carboxylic Acids, Boronic Acids, and Amines Using Cruciform Fluorophores
Published on: August 19, 2013
Triarylborane conjugated dicyanovinyl chromophores: intriguing optical properties and colorimetric anion
George Rajendra Kumar1, Samir Kumar Sarkar1, Pakkirisamy Thilagar1
1Inorganic and Physical Chemistry Department, Indian Institute of Science, Bangalore-560012, India. thilagar@ipc.iisc.ernet.in.
Abstract:
Three new triarylborane conjugated dicyanovinyl chromophores (Mes2B-π-donor-DCV); donor: N-methyldiphenylamine () and triphenylamine ( and [with two BMes2 substitutions]) of type A-D-A (acceptor-donor-acceptor) are reported. Compounds 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. Compound shows weak fluorescence compared to and . 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 of , and 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 of and , which allows for the naked-eye detection of F(-) and CN(-) ions. The anion binding mechanisms are established using NMR titration experiments.
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