Photonic materials derived from the [closo-B10H10]2− anion: tuning photophysical properties in [closo-B10H8-1-X-10-(4-Y-NC5H5)]−. Issue 4 (22nd December 2020)

• Record Type: Journal Article
• Authors: Kapuściński, Szymon; Abdulmojeed, Mustapha B.; Schafer, Tegan E.; Pietrzak, Anna; Hietsoi, Oleksandr; Friedli, Andrienne C.; Kaszyński, Piotr
• Is Part Of: Inorganic chemistry frontiers. Volume 8:Issue 4(2021)
• Page Start: 1066
• Page End: 1082
• Publication Date: 2020-12-22
• Subjects: Chemistry, Inorganic -- Periodicals; 546.05
• DOI: 10.1039/d0qi01353f
• Languages: English
• ISSNs: 2052-1553

Abstract

Abstract : Substitution of the parent [ closo -B10 H9 -1-NC5 H5 ] − either at the B(10) position or at the pyridine ring tunes absorption and emission energy. Abstract : The parent pyridine [ closo -B10 H9 -1-NC5 H5 ] − was substituted either at the antipodal B(10) position with CN, OAc, N3, I, Br, SCN, pyridine, OEt, and morpholine, or at the C(4) position of the pyridine ring with CN, COOEt, Me, and OMe groups. The substituent effects on electronic absorption and emission properties, and also on the boron cage geometry were investigated experimentally and with DFT (B3LYP/Def2TZVP) computational methods. Experimental and theoretical results were correlated with Hammett σ p parameters. Fluorescence was also investigated in the solid state and from aggregates (AIE). Solvent effects on photophysical properties of [ closo -B10 H9 -1-NC5 H5 ] − were correlated with E T 30 parameters, giving a slope of 0.71 for absorption and 0.17 for emission. Results demonstrated the substantial impact of the B(10) substituent on the HOMO and the C(4) substituent on the LUMO of the derivatives, which allows variation of the energy of the (π, π*) intramolecular charge transfer band in the range of 330–450 nm, and the emission energy in the range of 530–580 nm in MeCN solutions. The substituent effect on excitation energy is 2.4 times greater for substitution at the pyridine ring (LUMO control) than for the B(10) position (HOMO control). Additivity of the substituent effect was tested on [ closo -B10 H8 -1-(NC5 H4 CN)-10-OEt] − with λ max = 501.5 nm in MeCN and 560 nm in THF. These studies indicate that a substantial degree of control over photophysical properties is possible in derivatives of [ closo -B10 H10 ] 2− through a combination of substituent and solvent (medium) effects.