Benchmarking the dynamic luminescence properties and UV stability of B₁₈H₂₂-based materials

Abstract

The dynamic photoluminescent properties, and potential quenching mechanisms, of anti-B18H22, 4,4’-Br2-anti-B18H20, and 4,4’-I2-anti-B18H20 are investigated in solution and polymer films. UV stability studies of the neat powders show no decomposition...

A Window into the Workings of anti-B18H22 Luminescence—Blue-Fluorescent Isomeric Pair 3,3′-Cl2-B18H20 and 3,4′-Cl2-B18H20 (and Others)

“…These measured data nevertheless match well with those calculated for the 11 B chemical shifts (Table 6) of a molecular geometry for 6 shown in Figure 5. Two mono-chlorinated derivatives of 1, 3-Cl-B 18 H 21 (7) and 4-Cl-B 18 H 21 (8), were also observed. Although the isolation of these monochlorinated derivatives from other, multichlorinated, compounds was facile, the complete separation of 7 from 8 proved too difficult.…”

“…These are all factors of general practical benefit regarding the fabrication of optical devices. The photophysics of 1 may be modified by replacing some of its cluster terminal hydrogen atoms with substituents or ligands such as -SH [6], bromine [7,8], iodine [9], alkyls [10], and pyridine [11,12] to give molecules capable of, for example, environmentsensitive thermochromic luminescence [11], single-molecule multiple emissions [7], and the photosensitisation of oxygen [9]. Recently, metal-catalysed and metal-free nucleophilic substitution of the iodine group in 7-I-B 18 H 21 [9,13] has been demonstrated [14], leading to a series of luminescent B-N, B-O, and B-S substituted octadecaborane derivatives [14].…”

Macropolyhedral syn-B18H22, the “Forgotten” Isomer

“…Two of the largest known macropolyhedral boranes are the isomeric docosahydrooctadecaboranes B 18 H 22 . , They exhibit a unique molecular structure with two open faces and six acidic bridging hydrogen atoms (μ H -BB). − Their structural and chemical properties, together with their interaction with light, make B 18 H 22 a promising candidate for a wide range of applications, from energy storage, , semiconductor doping ,− to nano- and optoelectronic devices. − The molecular structure of B 18 H 22 can be viewed as two decaborane molecules condensed together, with each subcluster sharing atoms B(5) and B(6) in the decaborane numbering system, in common (Figure B,C). The isomer syn -B 18 H 22 on which this study focuses is a much less-studied (“forgotten”) system compared to its anti -B 18 H 22 isomer, and it has a 2-fold symmetry axis due to the fusion of two {B10} units sharing the B(5)–B(6) edge so that B(5)B(5′) and B(6)B(6′) (Figure B); in the anti -B 18 H 22 isomer, B(5)B(6′) and B(6)B(5′), which results in the inversion symmetry (Figure C). ,, What has stimulated most of the recent interest in anti -B 18 H 22 and its substituted derivatives has mainly been their luminescence properties. − Our interest in the “forgotten”, nonluminescent isomer, syn -B 18 H 22 , has been stimulated mainly by its unique geometry and size with respect to its use as constituents of purely borane, carbon-free self-assembled monolayers and its further use toward 2-dimensional membranes with thickness below 1 nm and with a 3D-aromatic character, as well as capping ligands of atomically precise metal nanoclusters, a newly emerging class of materials with adjustable geometry, size, and properties. , …”

Metal-Catalyzed and Metal-Free Nucleophilic Substitution of 7-I-B18H21

“…Anti -B 18 H 22 is a boron cluster that has gained recent attention as an inherently fluorescent boron hydride (λ em = 410 nm, Φ = 0.97) that has potential for various photoluminescence applications . To tune the luminescence properties of the parent compound, selective derivatization methods for this cluster are needed.…”