Open AccessMicrowave-Assisted Synthesis of the Red-Shifted Pentamethine Tetrahydroxanthylium Core with Absorbance within the Near Infrared-II Window
Author(s) -
Emmanuel Ramsey Buabeng,
Jason Dinh,
Takahiro Fukuda,
Homan Kang,
Satoshi Kashiwagi,
Hak Choi,
Maged Henary
Publication year - 2022
Publication title -
acs pharmacology and translational science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.271
H-Index - 10
ISSN - 2575-9108
DOI - 10.1021/acsptsci.2c00121
Subject(s) - absorbance , fluorescence , microwave , chemistry , quantum yield , photochemistry , halogenation , biological imaging , near infrared spectroscopy , yield (engineering) , infrared , nuclear chemistry , materials science , organic chemistry , chromatography , optics , physics , quantum mechanics , metallurgy
Thirteen red-shifted pentamethine dimethyl and diethylamino tetrahydroxanthylium derivatives have been successfully synthesized via the microwave-assisted approach. The optimized conditions developed in the synthesis provided an excellent yield in expedited reaction time. These newly synthesized dyes show well-defined optical properties resulting from the diverse substitutions at the central meso positions. The majority of the compounds have a maximum wavelength of absorbance within 946-1022 nm with extinction coefficients in the range of 9700-110,680 M -1 cm -1 in various solvents such as MeOH, EtOH, DMSO, DCM, MeCN, and DMF. These fluorophores, to the best of our knowledge, are the first NIR-II small molecules synthesized using microwave chemistry. We also investigated these dyes for their NIR fluorescence imaging capabilities. Diethylamino-substituted compounds and bromination resulted in higher uptake in the adrenal gland compared to dimethylamino fluorophores. In addition, micellar structures of compounds 7 and 15 improved the targetability of the original dyes to the bone marrow, lymph nodes, and nerves. Overall, NIR-II imaging has the potential to visualize biologically targeted tissues in living organisms.