Synthesis of N,O,B-Chelated Dipyrromethenes through an Unexpected Intramolecular Cyclisation: Enhanced Near-Infrared Emission in the Aggregate/Solid State

Yang Liu; Li-Ya Niu; Xue-Liang Liu; Peng-Zhong Chen; Yi-Shan Yao; Yu-Zhe Chen; Qing-Zheng Yang

doi:10.1002/chem.201802157

Synthesis of N,O,B-Chelated Dipyrromethenes through an Unexpected Intramolecular Cyclisation: Enhanced Near-Infrared Emission in the Aggregate/Solid State

Chemistry. 2018 Sep 12;24(51):13549-13555. doi: 10.1002/chem.201802157. Epub 2018 Aug 13.

Authors

Yang Liu¹, Li-Ya Niu¹, Xue-Liang Liu^{1

2}, Peng-Zhong Chen¹, Yi-Shan Yao³, Yu-Zhe Chen⁴, Qing-Zheng Yang¹

Affiliations

¹ Key Laboratory of Radiopharmaceuticals, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing, 100875, P.R. China.
² Analysis and Testing Laboratory, Xinxiang Medical University, Jinsui Road 601, Xinxiang, Henan, 453003, P.R. China.
³ Beijing Institute of pharmacology and Toxicology, Beijing, 100850, P.R. China.
⁴ Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190, P.R. China.

PMID: 29952087
DOI: 10.1002/chem.201802157

Abstract

The first example of the synthesis of mono-N,O-B-chelated dipyrromethene (BODIPY) derivatives through an unexpected intramolecular nucleophilic displacement of the fluorine by alkenols in the presence of boron trifluoride as Lewis acid is reported. The chlorine in the indacene core allowed for further structural modifications through nucleophilic substitutions or palladium-catalysed coupling reactions to afford new fluorophores with tuneable photophysical properties. Their expanded conjugation structure resulted in distinct red-shifted absorption and emission spectra in organic solutions. Furthermore, the twisted steric hindrance of the benzene substitution patterns suppressed aggregation-induced quenching, leading to an enhanced NIR emission in the aggregate/solid state, which was rarely observed for BODIPY dyes. Nanoparticles of the fluorophores formed by the assembly with the polymeric surfactant F127 were successfully used for bioimaging of living cells and for tumour-targeted imaging in a tumour-bearing mouse model.

Keywords: BODIPY; cyclization; dyes/pigments; fluorescence; in vivo bioimaging; tautomerism.