Syntheses and quadratic nonlinear optical properties of 2, 7-fluorenylene- and 1, 4-phenylene-functionalized o-carboranes. Issue 33 (1st August 2019)

• Record Type: Journal Article
• Authors: Jiang, Peng; Wang, Zhaojin; Moxey, Graeme J.; Morshedi, Mahbod; Barlow, Adam; Wang, Genmiao; Quintana, Cristóbal; Zhang, Chi; Cifuentes, Marie P.; Humphrey, Mark G.
• Is Part Of: Dalton transactions. Volume 48:Issue 33(2019)
• Page Start: 12549
• Page End: 12559
• Publication Date: 2019-08-01
• Subjects: Chemistry, Inorganic -- Periodicals; Chemistry, Physical and theoretical -- Periodicals; Chemistry, Inorganic -- Periodicals; 546.05
• DOI: 10.1039/c9dt02645b
• Languages: English
• ISSNs: 1477-9226

Abstract

Abstract : Electron-withdrawing o -carboranes C -functionalized by one 2-donor-7-fluorenyl unit are shown to exhibit strong quadratic optical nonlinearities at 1064 nm; appending two donor-functionalized fluorenyl groups further enhances the NLO coefficients. Abstract : o -Carboranes C -functionalized by (4-substituted-phen-1-yl)ethynyl-1, 4-phenyl groups or (2-substituted-fluoren-7-yl)ethynyl-2, 7-fluorenyl groups, in which the pendant functionalization is electron-withdrawing nitro or electron-donating diphenylamino groups, have been synthesized and in many cases structurally characterized. Diphenylamino-containing examples coupled via the two π-delocalizable bridges to the electron-accepting o -carborane unit exhibit the greater quadratic optical nonlinearities at 1064 nm (hyper-Rayleigh scattering, ns pulses), the nonlinearities also increasing on proceeding from 1, 4-phenylene- to 2, 7-fluorenylene-containing bridge. The most NLO-efficient example 2-( n -butyl)-1-(2-((9, 9-di( n -butyl)-2-( N, N -diphenylamino)-9 H -fluoren-7-yl)ethynyl)-9, 9-di( n -butyl)-9 H -fluoren-7-yl)-1, 2- ortho -carborane, consisting of diphenylamino donor, fluorenyl-containing bridge, o -carborane acceptor, and solubilizing n -butyl units, exhibits large 〈 β 〉HRS (230 × 10 −30 esu) and frequency-independent (two-level model) 〈 β 0 〉 (96 × 10 −30 esu) values. Coupling two (2-((9, 9-di( n -butyl)-2-( N, N -diphenylamino)-9 H -fluoren-7-yl)ethynyl)-9, 9-di( n -butyl)-9 H -fluoren-7-yl) units to the 1, 2- ortho -carborane core affords a di- C -functionalized compound with enhanced nonlinearities (309 × 10 −30 esu and 129 × 10 −30 esu, respectively).