Evaluation of Anisole‐Substituted Boron Difluoride Formazanate Complexes for Fluorescence Cell Imaging. Issue 44 (23rd September 2015)

• Record Type: Journal Article
• Authors: Maar, Ryan R.; Barbon, Stephanie M.; Sharma, Neha; Groom, Hilary; Luyt, Leonard G.; Gilroy, Joe B.
• Is Part Of: Chemistry. Volume 21:Issue 44(2015)
• Page Start: 15589
• Page End: 15599
• Publication Date: 2015-09-23
• Subjects: Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.201502821
• Languages: English
• ISSNs: 0947-6539

Abstract

<abstract abstract-type="main" xml:lang="en"> <title>Abstract</title> <p>Evaluation of three subclasses of boron difluoride formazanate complexes bearing <italic>o</italic>‐, <italic>m</italic>‐, and <italic>p</italic>‐anisole <italic>N</italic>‐aryl substituents (Ar) as readily accessible alternatives to boron dipyrromethene (BODIPY) dyes for cell imaging applications is described. While the wavelengths of maximum absorption (<italic>λ</italic><sub>max</sub>) and emission (<italic>λ</italic><sub>em</sub>) observed for each subclass of complexes, which differed by their carbon‐bound substituents (R), were similar, the emission quantum yields for <bold>7 a</bold>–<bold>c</bold> (R=cyano) were enhanced relative to <bold>8 a</bold>–<bold>c</bold> (R=nitro) and <bold>9 a</bold>–<bold>c</bold> (R=phenyl). Complexes <bold>7 a</bold>–<bold>c</bold> and <bold>8 a</bold>–<bold>c</bold> were also significantly easier to reduce electrochemically to their radical anion and dianion forms compared to <bold>9 a</bold>–<bold>c</bold>. Within each subclass, the <italic>o</italic>‐substituted derivatives were more difficult to reduce, had shorter <italic>λ</italic><sub>max</sub> and <italic>λ</italic><sub>em</sub>, and lower emission quantum yields than the <italic>p</italic>‐substituted analogues as a result of sterically driven twisting of the <italic>N</italic>‐aryl substituents and a decrease in the degree of π‐conjugation. The <italic>m</italic>‐substituted complexes were the least difficult to reduce and possessed intermediate <italic>λ</italic><sub>max</sub>, <italic>λ</italic><sub>em</sub>, and quantum yields. The complexes studied also exhibited large Stokes shifts (82–152 nm, 2143–5483 cm<sup>−1</sup>). Finally, the utility of complex <bold>7 c</bold> (Ar=<italic>p</italic>‐anisole, R=cyano), which can be prepared for just a few dollars per gram, for fluorescence cell imaging was demonstrated. The use of <bold>7 c</bold> and 4′, 6‐diamino‐2‐phenylindole (DAPI) allowed for simultaneous imaging of the cytoplasm and nucleus of mouse fibroblast cells.</p> </abstract>