0000000001314148
AUTHOR
Pavel Kubát
Tuning the photophysical properties of anti-B18H22: efficient intersystem crossing between excited singlet and triplet states in new 4,4'-(HS)2-anti-B18H20.
The tuning of the photophysical properties of the highly fluorescent boron hydride cluster anti-B18H22 (1), by straightforward chemical substitution to produce 4,4'-(HS)2-anti-B18H20 (2), facilitates intersystem crossing from excited singlet states to a triplet manifold. This subsequently enhances O2((1)Δg) singlet oxygen production from a quantum yield of ΦΔ ∼ 0.008 in 1 to 0.59 in 2. This paper describes the synthesis and full structural characterization of the new compound 4,4'-(HS)2-anti-B18H20 (2) and uses UV-vis spectroscopy coupled with density functional theory (DFT) and ab initio computational studies to delineate and explain its photophysical properties.
Distinct Photophysics of the Isomers of B18H22 Explained
The photophysics of the two isomers of octadecaborane(22), anti- and syn-B 18H 22, have been studied by UV-vis spectroscopic techniques and theoretical computational methods. In air-saturated hexane, anti-B 18H 22 shows fluorescence with a high quantum yield, Φ F = 0.97, and singlet oxygen O 2( 1Δ g) production (Φ Δ ∼ 0.008). Conversely, isomer syn-B 18H 22 shows no measurable fluorescence, instead displaying much faster, picosecond nonradiative decay of excited singlet states. Computed potential energy hypersurfaces (PEHs) for both isomers rationalize these data, pointing to a deep S 1 minimum for anti-B 18H 22 and a conical intersection (CI) between its S 0 and S 1 states that lies 0.51 e…
Effect of Iodination on the Photophysics of the Laser Borane anti-B18H22: Generation of Efficient Photosensitizers of Oxygen
Treatment of the laser borane anti-B18H22 (compound 1) with iodine in ethanol gives the monoiodinated derivative 7-I-anti-B18H21 (compound 2) in 67% yield, or, by reaction with iodine or ICl in the presence of AlCl3 in dichloromethane, the diiodinated derivative 4,4'-I2-anti-B18H20 (compound 3) in 85% yield. On excitation with 360 nm light, both compounds 2 and 3 give strong green phosphorescent emissions (λmax = 525 nm, ΦL = 0.41 and λmax = 545 nm, ΦL = 0.71 respectively) that are quenched by dioxygen to produce O2(1Δg) singlet oxygen with quantum yields of ΦΔ = 0.52 and 0.36 respectively. Similarly strong emissions can be stimulated via the nonlinear process of two-photon absorption when …
CCDC 1859436: Experimental Crystal Structure Determination
Related Article: Michael G. S. Londesborough, Jiří Dolanský, Jonathan Bould, Jakub Braborec, Kaplan Kirakci, Kamil Lang, Ivana Císařová, Pavel Kubát, Daniel Roca-Sanjuán, Antonio Francés-Monerris, Lenka Slušná, Eva Noskovičová, Dušan Lorenc|2019|Inorg.Chem.|58|10248|doi:10.1021/acs.inorgchem.9b01358
CCDC 1859437: Experimental Crystal Structure Determination
Related Article: Michael G. S. Londesborough, Jiří Dolanský, Jonathan Bould, Jakub Braborec, Kaplan Kirakci, Kamil Lang, Ivana Císařová, Pavel Kubát, Daniel Roca-Sanjuán, Antonio Francés-Monerris, Lenka Slušná, Eva Noskovičová, Dušan Lorenc|2019|Inorg.Chem.|58|10248|doi:10.1021/acs.inorgchem.9b01358
CCDC 912917: Experimental Crystal Structure Determination
Related Article: Vicenta Saurí, Josep M. Oliva, Drahomír Hnyk, Jonathan Bould, Jakub Braborec, Manuela Merchán, Pavel Kubát, Ivana Císařová, Kamil Lang, and Michael G. S. Londesborough|2013|Inorg.Chem.|52|9266|doi:10.1021/ic4004559