Diazaborolyl-boryl push–pull systems with ethynylene–arylene bridges as ‘turn-on’ fluoride sensors

Abstract

. (2012) 'Diazaborolyl-boryl push pull systems with ethynylene arylene bridges as`turn-on' uoride sensors. ', Dalton transactions., 41 (34). pp. 10328-10346. Further information on publisher's website:http://dx.doi.org/10.1039/c2dt30438dPublisher's copyright statement:Additional information: Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-pro t purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. IntroductionConjugated organic molecules and polymers with three-coordinate boron units as building blocks have attracted considerable interest because of their linear and non-linear optical and electronic properties, which make them potentially useful in functional materials. 1 Three-coordinate boron generally behaves as a π-acceptor due to its vacant p-orbital, which stabilizes the LUMO of an adjacent conjugated π-electron system and thus lowers the HOMO-LUMO gap of these molecules. This field of research has been dominated by the use of the dimesitylboryl group (BMes 2 , Mes = 2,4,6-Me 3 C 6 H 2 ), in which the unsaturated boron centre is stabilized towards oxidation and hydrolysis by the steric shielding of the four orthomethyl groups. [2][3][4][5] The BMes 2 group is considered to have an acceptor strength between that of NO 2 -and CN-groups. 6,7 Such electron-deficient compounds are efficient electron-transporting and/or emitting layers in organic light emitting diodes (OLEDs). 5 Compounds with BMes 2 groups are often strongly coloured and/or luminescent, 8 which renders them useful as colorimetric or luminescent sensors for fluoride ions. [9][10][11][12][13]

Electrochemical and spectroelectrochemical studies of C-benzodiazaborolyl-ortho-carboranes

“…The four independent molecules in the unit cell of bromobenzodiazaborole 19 show mesityl groups which are nearly orthogonally oriented to the plane of the heterocycle with interplanar angles (ω) between 75.2 and 87.5° (Table S1). These values are similar to the interplanar angles ω observed in the molecular structures for compounds 6-12 shown in 20 The bonding parameters within the benzodiazaborole units were similar to those of other previously reported structures. 16,[18][19][20][21] The carborane C1 -borolyl B bond lengths increases from 1.580 Å in 15 with NH groups via 1.586-1.597 Å with NPh substituents to 1.594-1.609 Å with N-alkyl groups reflecting the increased bulk of the substituents.…”

“…In our group the 2-bromo-1,3,2-benzodiazaborole 2-Br-1,3-Et 2 -1,3,2-N 2 BC 6 H 4 17 has been frequently used as a precursor for many fluorescent benzodiazaboroles [18][19][20][21][22] including carboranes 1-5 (Chart I). Analogously, 2-Br-1,3-Ph 2 -1,3,2-N 2 BC 6 H 4 (16) 19 (Scheme 3) was utilized as a starting material for benzodiazaborole dyes such as 6 and 7.…”

The role of 2,3-dihydro-1-H-1,3,2-diazaboroles in luminescent molecules

“…Similarly, crystalline 2-(5 -dimesitylboryl-2 -thienylethynyl)-1,3-diethyl-1,3,2-benzodiazaborole (42) was synthesized [43]. Thiophenes and oligo-thiophenes are ideal building blocks in luminescent molecules.…”

“…Treatment of 135 with two equivalents of lithium phenylacetylide gave rise to the formation of 137, while derivative 136 was further functionalized to compound 138 by combination with a twofold amount of lithiated 4-dimesitylboryl-phenylacetylene (Scheme 26) [43].…”

“…Various donor-and acceptor groups are employed. Bond lengths and interplanar angles of interest of compounds 22 [33], 24, 26 [33], 51-56 [51], 83, 84 [30] with phenyl-based linkers, 27, 28, 30-33 with diphenylacetylene substituents at boron [39], 35, 36, 38-40, 42 with arylacetylide groups [41][42][43] and 44, 45, 46 [33], 49, 50 [46], 57, 58, 60 [51], 68 [53], 74 [55] and 86 [30] with thiophene-derived spacers are listed in Table S1 (Supporting information).…”