title: Highly fluorescent solid-state asymmetric spirosilabifluorene derivatives.
abstract: A series of four asymmetrically aryl-substituted 9,9'-spiro-9-silabifluorene (SSF) derivatives, 2,2'-di-tert-butyl-7,7'-diphenyl-9,9'-spiro-9-silabifluorene (PhSSF), 2,2'-di-tert-butyl-7,7'-dipyridin-2-yl-9,9'-spiro-9-silabifluorene (PySSF), 2,2'-di-tert-butyl-7,7'-dibiphenyl-4-yl-9,9'-spiro-9-silabifluorene (BPhSSF), and 2,2'-di-tert-butyl-7,7'-bis(2',2' '-bipyridin-6-yl)-9,9'-spiro-9-silabifluorene (BPySSF) are prepared through the cyclization of the corresponding 2,2'-dilithiobiphenyls with silicon tetrachloride. These novel spiro-linked silacyclopentadienes (siloles) form transparent and stable amorphous films with relatively high glass transition temperatures (T(g) = 203-228 degrees C). The absorbance spectrum of each compound shows a significant bathochromic shift relative to that of the corresponding carbon analogue as a result of the effective sigma-pi conjugation between the sigma orbital of the exocyclic Si-C bond and the pi orbital of the oligoarylene fragment. Solid-state films exhibit intense violet-blue emission (lambda(PL) = 398-415 nm) with high absolute photoluminescence quantum yields (phi(PL) = 30-55%).
authors.affiliation: Optical Sciences Division, US Naval Research Laboratory, Washington, DC 20375, USA. sangho@ccs.nrl.navy.mil
authors.forename: Sang Ho
authors.initials: SH
authors.lastname: Lee
authors.forename: Bo-Bin
authors.initials: BB
authors.lastname: Jang
authors.forename: Zakya H
authors.initials: ZH
authors.lastname: Kafafi
mesh_terms: D001713:Biphenyl Compounds / Q000138:chemical synthesis / Q000737:chemistry; D002712:Chlorides / Q000138:chemical synthesis / Q000737:chemistry; D003500:Cyclization; D004563:Electrochemistry; D005449:Fluorenes / Q000737:chemistry; D049449:Luminescence; D015394:Molecular Structure; D017646:Organosilicon Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D011789:Quantum Theory; D017655:Silicon Compounds / Q000138:chemical synthesis / Q000737:chemistry; D013141:Spiro Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D013696:Temperature
chemical_list: D001713:Biphenyl Compounds; D002712:Chlorides; D005449:Fluorenes; D017646:Organosilicon Compounds; D017655:Silicon Compounds; D013141:Spiro Compounds; C039676:silicon tetrachloride