Reviews and Accounts ARKIVOC 2013 (i) 175-184
Stabilization of -conjugated organoboron scaffolds by structural constraint
Tobias A. Schaub and Milan Kivala*
Department of Chemistry and Pharmacy, University of Erlangen-Nürnberg, Henkestraße 42, 91054 Erlangen, Germany E-mail: milan.kivala@fau.de
Abstract
Tricoordinate boron with its vacant p-orbital is a potent -acceptor in conjugated organic molecules relevant to the construction of novel optoelectronic materials. The new concept of kinetic stabilization by structural constraint offers a powerful strategy that enables the synthesis of hitherto unprecedented boron-containing polycyclic aromatic hydrocarbons. These new planarized organoboranes feature intriguing photophysical and self-assembly properties and hence are particularly interesting for application in organic optoelectronic devices.
Keywords: Polycyclic aromatic hydrocarbons, organoboranes, kinetic stabilization, structural constraint
Owing to the increased environmental awareness and diminishing natural resources, the last decades have witnessed vigorous research activities in the field of energy-saving technologies with low environmental impact. In this regard, -conjugated organic molecules emerged as one of the most promising candidates for the construction of innovative optoelectronic devices.1 The main reason is the ease of structural tuning by means of organic synthesis which allows for efficient tailoring of their photophysical properties, supramolecular behavior and thus of the resulting function.
A powerful approach to modify the nature of the parent -conjugated systems is to incorporate heteroatoms into the polycyclic carbon-based scaffolds.2,3 Among the elements applicable to this methodology, boron is particularly qualified due to its electronic structure and its strategic position in the periodic table adjacent to carbon. Thereby, the intrinsic propensity of any tricoordinate boron species to reach the desired octet configuration is directly reflected in i) its pronounced Lewis acidity, ii) its trigonal planar geometry, and iii) the resulting effective orbital interaction of the vacant p-orbital on boron with the adjacent -systems. Hence, a key issue for the construction of new trivalent organoboranes is to overcome their inherent sensitivity against moisture, oxygen and nucleophiles.
Page 175 ©ARKAT-USA, Inc
0
