Synthesis and Luminescent Properties of Lewis Base-Appended Borafluorenes

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• 作者：Christopher J. Berger ; Gang He ; Christian Merten ; Robert McDonald ; Michael J. Ferguson ; Eric Rivard
• 刊名：Inorganic Chemistry
• 出版年：2014
• 出版时间：February 3, 2014
• 年：2014
• 卷：53
• 期：3
• 页码：1475-1486
• 全文大小：588K
• ISSN：1520-510X

文摘

A series of Lewis base adducts of 9-bromo-9-borafluorene (BrBFl鈥揕B, LB = IPr, IPrCH₂, PPh₃, and PCy₃), parent borafluorenes (HBFl鈥揑Pr and HBFl鈥揑PrCH₂), and the bisadduct [(DMAP)₂BFl]Br were prepared and structurally characterized (IPr = [(HCNDipp)₂C:], IPrCH₂ = [(HCNDipp)₂C鈺怌H₂], Dipp = 2,6-i-Pr₂C₆H₃, and DMAP = N,N-dimethylaminopyridine). The adducts BrBFl鈥揑Pr, BrBFl鈥揚Ph₃, BrBFl鈥揚Cy₃, [(DMAP)₂BFl]Br, BrBFl鈥揑PrCH₂, and HBFl鈥揑PrCH₂ were found to exhibit bright blue luminescence with low to moderately high quantum efficiencies (19 to 63%). Selective irradiation at different excitation wavelengths revealed the presence of two distinct emission processes in the adducts BrBFl鈥揕B, leading to a ligand-independent, presumably borafluorene-based, blue light emission at 435 nm and another less intense emission band in the ultraviolet region (315鈥?24 nm); [(DMAP)₂BFl]Br exhibits an emission profile that tails into the visible region. Time-dependent density functional theory studies are also included for representative borafluorene adducts. With a judicious choice of functional groups at boron, one can envisage the future generation of a whole library of 4-coordinate borafluorene-based luminogens that complement the efficient light-emitting behavior known for the widely studied boron-dipyrromethene analogues.