Arylisoquinoline-derived organoboron dyes with a triaryl skeleton show dual fluorescence

[EN] Four new dyes that derive from borylated arylisoquinolines were prepared, containing a third aryl residue (naphthyl, 4-methoxynaphthyl, pyrenyl or anthryl) that is linked via an additional stereogenic axis. The triaryl cores were synthesized by Suzuki couplings and then transformed into boronic acid esters by employing an Ir(I)-catalyzed reaction. The chromophores show dual emission behavior, where the long-wavelength emission band can reach maxima close to 600 nm in polar solvents. The fluorescence quantum yields of the dyes are generally in the range of 0.2¿0.4, reaching in some cases values as high as 0.5¿0.6. Laserflash photolysis provided evidence for the existence of excited triplet states. The dyes form fluoroboronate complexes with fluoride anions, leading to the observation of the quenching of the long-wavelength emission band and ratiometric response by the build-up of a hypsochromically shifted emission signal.Funding by the Spanish Ministry of Economy, Industry, and Competitiveness (CTQ2014-54729-C2-1-P for U.P., CTQ2013-48164-C2-1-P and CTQ2013-48164-C2-2-P for A.R., Ramon y Cajal contracts RYC-2013-12585 for A.R. and RYC-2015-17737 for I.V.), the Spanish Ministry of Science, Innovation, and Universities (CTQ2017-89832-P for U.P., CTQ2016-78875-P for M.C.J., and CTQ2017-89416-R for I.V.), the European Research and Development Fund, and the Andalusian Government (2012/FQM-2140 for U.P., 2009/FQM-4537 and 2012/FQM-1078 for A.R) is gratefully acknowledged.Pais, VF.; Neumann, T.; Vayá Pérez, I.; Jiménez Molero, MC.; Ros, A.; Pischel, U. (2019). Arylisoquinoline-derived organoboron dyes with a triaryl skeleton show dual fluorescence. Beilstein Journal of Organic Chemistry. 15:2612-2622. https://doi.org/10.3762/BJOC.15.254S2612262215Frath, D., Massue, J., Ulrich, G., & Ziessel, R. (2014). Lumineszierende Materialien: Fixierung von π-konjugierten und heterocyclischen Liganden mit Bor(III). Angewandte Chemie, 126(9), 2322-2342. doi:10.1002/ange.201305554Ji, L., Griesbeck, S., & Marder, T. B. (2017). Recent developments in and perspectives on three-coordinate boron materials: a bright future. Chemical Science, 8(2), 846-863. doi:10.1039/c6sc04245gVanga, M., Lalancette, R. A., & Jäkle, F. (2019). Controlling the Optoelectronic Properties of Pyrene by Regioselective Lewis Base‐Directed Electrophilic Aromatic Borylation. Chemistry – A European Journal, 25(43), 10133-10140. doi:10.1002/chem.201901231Alcaide, M. M., Santos, F. M. F., Pais, V. F., Carvalho, J. I., Collado, D., Pérez-Inestrosa, E., … Pischel, U. (2017). Electronic and Functional Scope of Boronic Acid Derived Salicylidenehydrazone (BASHY) Complexes as Fluorescent Dyes. The Journal of Organic Chemistry, 82(14), 7151-7158. doi:10.1021/acs.joc.7b00601Bozdemir, O. A., Guliyev, R., Buyukcakir, O., Selcuk, S., Kolemen, S., Gulseren, G., … Akkaya, E. U. (2010). Selective Manipulation of ICT and PET Processes in Styryl-Bodipy Derivatives: Applications in Molecular Logic and Fluorescence Sensing of Metal Ions. Journal of the American Chemical Society, 132(23), 8029-8036. doi:10.1021/ja1008163Niu, L.-Y., Guan, Y.-S., Chen, Y.-Z., Wu, L.-Z., Tung, C.-H., & Yang, Q.-Z. (2012). BODIPY-Based Ratiometric Fluorescent Sensor for Highly Selective Detection of Glutathione over Cysteine and Homocysteine. Journal of the American Chemical Society, 134(46), 18928-18931. doi:10.1021/ja309079fZheng, Q., Xu, G., & Prasad, P. N. (2008). Conformationally Restricted Dipyrromethene Boron Difluoride (BODIPY) Dyes: Highly Fluorescent, Multicolored Probes for Cellular Imaging. Chemistry - A European Journal, 14(19), 5812-5819. doi:10.1002/chem.200800309Han, J., Loudet, A., Barhoumi, R., Burghardt, R. C., & Burgess, K. (2009). A Ratiometric pH Reporter For Imaging Protein-dye Conjugates In Living Cells. Journal of the American Chemical Society, 131(5), 1642-1643. doi:10.1021/ja8073374Kolemen, S., Işık, M., Kim, G. M., Kim, D., Geng, H., Buyuktemiz, M., … Akkaya, E. U. (2015). Intracellular Modulation of Excited-State Dynamics in a Chromophore Dyad: Differential Enhancement of Photocytotoxicity Targeting Cancer Cells. Angewandte Chemie, 127(18), 5430-5434. doi:10.1002/ange.201411962Bachollet, S. P. J. T., Volz, D., Fiser, B., Münch, S., Rönicke, F., Carrillo, J., … Harrity, J. P. A. (2016). A Modular Class of Fluorescent Difluoroboranes: Synthesis, Structure, Optical Properties, Theoretical Calculations and Applications for Biological Imaging. Chemistry - A European Journal, 22(35), 12430-12438. doi:10.1002/chem.201601915Frath, D., Didier, P., Mély, Y., Massue, J., & Ulrich, G. (2017). Vectorization and Intracellular Distribution of a Two-Photon-Absorbing, Near-Infrared-Emitting π-Extended Boranil Dye. ChemPhotoChem, 1(4), 109-112. doi:10.1002/cptc.201700012Melaimi, M., & Gabbaï, F. P. (2005). A Heteronuclear Bidentate Lewis Acid as a Phosphorescent Fluoride Sensor. Journal of the American Chemical Society, 127(27), 9680-9681. doi:10.1021/ja053058sHudnall, T. W., Kim, Y.-M., Bebbington, M. W. P., Bourissou, D., & Gabbaï, F. P. (2008). Fluoride Ion Chelation By a Bidentate Phosphonium/Borane Lewis Acid. Journal of the American Chemical Society, 130(33), 10890-10891. doi:10.1021/ja804492yWade, C. R., Broomsgrove, A. E. J., Aldridge, S., & Gabbaï, F. P. (2010). Fluoride Ion Complexation and Sensing Using Organoboron Compounds. Chemical Reviews, 110(7), 3958-3984. doi:10.1021/cr900401aBai, D.-R., Liu, X.-Y., & Wang, S. (2007). Charge-Transfer Emission Involving Three-Coordinate Organoboron: V-Shape versus U-Shape and Impact of the Spacer on Dual Emission and Fluorescent Sensing. Chemistry - A European Journal, 13(20), 5713-5723. doi:10.1002/chem.200700364Proń, A., Zhou, G., Norouzi-Arasi, H., Baumgarten, M., & Müllen, K. (2009). Controlling the Charge Transfer in Phenylene-Bridged Borylene−Amine π-Conjugated Systems. Organic Letters, 11(16), 3550-3553. doi:10.1021/ol9012487Pan, H., Fu, G.-L., Zhao, Y.-H., & Zhao, C.-H. (2011). Through-Space Charge-Transfer Emitting Biphenyls Containing a Boryl and an Amino Group at theo,o′-Positions. Organic Letters, 13(18), 4830-4833. doi:10.1021/ol201909rBonn, A. G., & Wenger, O. S. (2015). Charge Transfer Emission in Oligotriarylamine–Triarylborane Compounds. The Journal of Organic Chemistry, 80(8), 4097-4107. doi:10.1021/acs.joc.5b00416Pais, V. F., Lineros, M., López-Rodríguez, R., El-Sheshtawy, H. S., Fernández, R., Lassaletta, J. M., … Pischel, U. (2013). Preparation and pH-Switching of Fluorescent Borylated Arylisoquinolines for Multilevel Molecular Logic. The Journal of Organic Chemistry, 78(16), 7949-7961. doi:10.1021/jo401147tPais, V. F., Lassaletta, J. M., Fernández, R., El-Sheshtawy, H. S., Ros, A., & Pischel, U. (2014). Organic Fluorescent Thermometers Based on Borylated Arylisoquinoline Dyes. Chemistry - A European Journal, 20(25), 7638-7645. doi:10.1002/chem.201402027Domínguez, Z., López-Rodríguez, R., Álvarez, E., Abbate, S., Longhi, G., Pischel, U., & Ros, A. (2018). Azabora[5]helicene Charge-Transfer Dyes Show Efficient and Spectrally Variable Circularly Polarized Luminescence. Chemistry - A European Journal, 24(48), 12660-12668. doi:10.1002/chem.201801908Zhu, L., Shabbir, S. H., Gray, M., Lynch, V. M., Sorey, S., & Anslyn, E. V. (2006). A Structural Investigation of the N−B Interaction in ano-(N,N-Dialkylaminomethyl)arylboronate System. Journal of the American Chemical Society, 128(4), 1222-1232. doi:10.1021/ja055817cBoscá, F., Cuquerella, M. C., Pais, V. F., Ros, A., & Pischel, U. (2017). Excited-State Pathways of Four-Coordinate N,C-Chelate Organoboron Dyes. ChemPhotoChem, 2(1), 34-41. doi:10.1002/cptc.201700176Hara, M., Tojo, S., Kawai, K., & Majima, T. (2004). Formation and decay of pyrene radical cation and pyrene dimer radical cation in the absence and presence of cyclodextrins during resonant two-photon ionization of pyrene and sodium 1-pyrene sulfonate. Phys. Chem. Chem. Phys., 6(13), 3215-3220. doi:10.1039/b403409kMelhuish, W. H. (1960). A STANDARD FLUORESCENCE SPECTRUM FOR CALIBRATING SPECTRO-FLUOROPHOTOMETERS. The Journal of Physical Chemistry, 64(6), 762-764. doi:10.1021/j100835a014Melhuish, W. H. (1961). QUANTUM EFFICIENCIES OF FLUORESCENCE OF ORGANIC SUBSTANCES: EFFECT OF SOLVENT AND CONCENTRATION OF THE FLUORESCENT SOLUTE1. The Journal of Physical Chemistry, 65(2), 229-235. doi:10.1021/j100820a00