Evaluation of Anisole‐Substituted Boron Difluoride Formazanate Complexes for Fluorescence Cell Imaging |
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Authors: | Ryan R. Maar Stephanie M. Barbon Neha Sharma Hilary Groom Prof. Dr. Leonard G. Luyt Prof. Dr. Joe B. Gilroy |
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Affiliation: | 1. Department of Chemistry, The University of Western Ontario, 1151 Richmond St. N., London, Ontario N6A 5B7 (Canada);2. The Centre for Advanced Materials and Biomaterials Research (CAMBR), The University of Western Ontario, 1151 Richmond St. N., London, Ontario N6A 5B7 (Canada);3. Department of Oncology, London Regional Cancer Program, 790 Commissioners Rd. E., London, Ontario N6A 4L6 (Canada);4. Department of Medical Imaging, The University of Western Ontario, 1151 Richmond St. N., London, Ontario N6A 5B7 (Canada) |
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Abstract: | Evaluation of three subclasses of boron difluoride formazanate complexes bearing o‐, m‐, and p‐anisole N‐aryl substituents (Ar) as readily accessible alternatives to boron dipyrromethene (BODIPY) dyes for cell imaging applications is described. While the wavelengths of maximum absorption (λmax) and emission (λem) observed for each subclass of complexes, which differed by their carbon‐bound substituents (R), were similar, the emission quantum yields for 7 a – c (R=cyano) were enhanced relative to 8 a – c (R=nitro) and 9 a – c (R=phenyl). Complexes 7 a – c and 8 a – c were also significantly easier to reduce electrochemically to their radical anion and dianion forms compared to 9 a – c . Within each subclass, the o‐substituted derivatives were more difficult to reduce, had shorter λmax and λem, and lower emission quantum yields than the p‐substituted analogues as a result of sterically driven twisting of the N‐aryl substituents and a decrease in the degree of π‐conjugation. The m‐substituted complexes were the least difficult to reduce and possessed intermediate λmax, λem, and quantum yields. The complexes studied also exhibited large Stokes shifts (82–152 nm, 2143–5483 cm?1). Finally, the utility of complex 7 c (Ar=p‐anisole, R=cyano), which can be prepared for just a few dollars per gram, for fluorescence cell imaging was demonstrated. The use of 7 c and 4′,6‐diamino‐2‐phenylindole (DAPI) allowed for simultaneous imaging of the cytoplasm and nucleus of mouse fibroblast cells. |
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Keywords: | boron cell imaging fluorescent dyes formazanate ligands substituent effects |
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