Hydrolysis Kinetic of New Laser Material n-B₁₈H₂₂

A Series of Ultra-Efficient Blue Borane Fluorophores

“…In the parent borane, this chemical shift of μH(9,10), viz. ( 1 H), −0.38 ppm, is also considerably to a lower field compared to the adjacent μH (8,9) proton at −2.87 ppm. This difference may thus be a combination both of the slightly different cluster position relative to the other subcluster, together with the interaction between the μH(9,10) proton and the terminal proton on B(2), which are separated by 2.11(2) Å in the crystal and which is also less than the sum of the van der Waals radii, 2.4 Å.…”

“…5 This +0.58 ppm change in 1 compares to the effective +1.21 ppm difference in the chemical shift of μH(9,10) in 12 (0.83 + 0.38 = 1.21 ppm). This may be a consequence both of the considerably closer approach of the internally structurally constrained Cl and H positions for μH(9,10), 2.33 Å, and of the electronegativity of chlorine, compared to that for μH (8,9) and the benzene ring centroid in anti-B 18 H 22 •C 6 H 6 of 2.816 Å. 18 Further Considerations of Structural Aspects.…”

“…It was previously postulated, 13 from a consideration of the aromatic-solvent-induced chemical shift (ASIS) change of +0.58 ppm in the proton chemical shifts between CD 2 Cl 2 and C 6 D 6 solutions of anti-B 18 H 22 , that the µH(8,9) bridging proton might undergo a weak interaction with the aromatic solvent similar to that seen in nido-B 10 H 14 , 17 and this has been subsequently confirmed in the crystal structures of the benzene solvates of anti-B 18 H 22 , 18 4,4'-(SH) 2 -anti-B 18 H 20 , 3 and 4,4'-I 2 -anti-B 18 H 20 . 5 This +0.58 ppm change in 1 compares to the effective +1.21 ppm difference in the chemical shift of µH (9,10) in 12 (0.83 + 0.38 = 1.21 ppm). This may be a consequence both of the considerably closer approach of the internally structurally constrained Cl and H positions for µH(9,10), 2.33 Å, and of the electronegativity of chlorine, compared to that for µH(8,9) and the benzene ring centroid in anti-B 18 H 22 .C 6 H 6 of 2.816 Å.…”

“…Their measured interatomic separation of 2.36(3) Å (2.33 Å, calculated) is notably lower than the 2.95 Å sum of the van der Waals radii of the atoms. In the parent borane, this chemical shift of µH (9,10), viz. ( 1 H), −0.38 ppm, is also considerably to lower field compared to the adjacent µH(8,9) proton at −2.87 ppm.…”

“…The photophysics of compound 1 may be modified by the introduction of substituents or ligands to replace the terminal hydrogen atoms on the cluster such as −SH, bromine, iodine, and pyridine , to give molecules capable of, for example, environmentally sensitive thermochromic luminescence, single-molecule multiple emissions, and the photosensitization of oxygen . In addition, the optical properties of the parent compound have been shown to tolerate dissolution in aqueous micelles , in work that has been recently patented . Previously, luminescence from 1 in water had been unachievable due to insolubility of its neutral form and the nonluminescent nature of its anion [B 18 H 21 ] − , which in aqueous environments, is readily generated through deprotonation of one of the compound’s highly acidic bridging hydrogen atoms.…”