Synthesis and Spectroscopic Properties of Fused‐Ring‐Expanded Aza‐Boradiazaindacenes |
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| Authors: | Dr Hua Lu Dr Soji Shimizu Dr John Mack Prof Zhen Shen Prof Nagao Kobayashi |
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| Institution: | 1. State Key Laboratory of Coordination Chemistry, Nanjing National Laboratory of Microstructures, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093 (China), Fax: (+86)?25‐8331‐4502;2. Department of Chemistry, Graduate School of Science, Tohoku University, Sendai 980–8578 (Japan), Fax: : (+81)?22‐795‐7719 |
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| Abstract: | A series of fused‐ring‐expanded aza‐boradiazaindacene (aza‐BODIPY) dyes have been synthesized by reacting arylmagnesium bromides with phthalonitriles or naphthalenedicarbonitriles. An analysis of the structure–property relationships has been carried out based on X‐ray crystallography, optical spectroscopy, and theoretical calculations. Benzo and 1,2‐naphtho‐fused 3,5‐diaryl aza‐BODIPY dyes display markedly red shifted absorption and emission bands in the near‐IR region (>700 nm) due to changes in the energies of the frontier MOs relative to those of 1,3,5,7‐tetraaryl aza‐BODIPYs. Only one 1,2‐naphtho‐fused aza‐BODIPY of the three possible isomers is formed due to steric effects, and 2,3‐naphtho‐fused compounds could not be characterized because the final BF2 complexes are unstable in solution. The incorporation of a N(CH3)2 group at the para‐positions of a benzo‐fused 3,5‐diaryl aza‐BODIPY quenches the fluorescence in polar solvents and results in a ratiometric pH response, which could be used in future practical applications as an NIR “turn‐on” fluorescence sensor. |
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| Keywords: | BODIPYs density functional theory dyes/pigments fluorescence IR spectroscopy |
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