Switching and tuning organic solid-state luminescence via a supramolecular approach

Savarimuthu Philip Anthony, Sunil Varughese, Sylvia M. Draper
2009 Chemical Communications  
Unusual intermolecular interactions of organic luminescent acid, 2-cyano-3(4-(diphenylamino)phenyl)acrylic acid (CDPA), with amines lead to the formation of supramolecular luminescence systems with switchable and tunable solid-state luminescence. Organic solid-state luminescent materials have a potential role in a wide range of high-technology applications such as organic light emitting diodes (OLEDs), 1 semiconductor lasers 2 and fluorescent sensors. 3 In particular the switching and tuning of
more » ... organic solid-state luminescence is of current interest to fundamental research and practical applications. In solution, solvatochromism, 4,5 the addition of metal ions, 5a,6 and the variation of substitution 5 or pH 5a,6,7 lead to the tuning and switching of the luminescence. However organic solid-state luminescence, which is rare due to the aggregation quenching effect, has mostly been tuned by the modification of substitutions on single molecules 8 or the exploitation of polymorphism. 9,10 The latter approach is effective as the optical properties in the solid are controlled by molecular organization but it offers little predictability, the former requires interactive synthetic improvement. Supramolecular chemistry provides a versatile approach to tuning and switching solid-state luminescence by controlling the molecular organization through weak interactions. 11 For example, solvent dependent solid-state luminescence has been demonstrated by supramolecular host systems generated from the mixing of luminescent organic acids and amines. 12 In general, deprotonation and protonation provides a simple strategy to tune or switch the emission of organic luminescent acids across a wide wavelength range. Furthermore the amine induced manipulation of the acid protons, via subtle variations in H-bond formation and controlled deprotonation, creates an opportunity to gradually tune the solid-state luminescence and simultaneously provides a platform for amine sensing. Herein, we report supramolecular luminescence systems based on 2-cyano-3(4-(diphenylamino)phenyl)acrylic acid (CDPA) and amines (pyridine (1), pyrrolidine (2), piperidine (3) and morpholine (4)). These systems exhibit blue shifted luminescence compared to the parent acid and in the case of 3 solvent dependent solid-state luminescence was observed. CDPA was synthesized following the reported procedure 13 and crystallized from CH 3 CN by slow evaporation. The single
doi:10.1039/b914027a pmid:20024259 fatcat:55wiqlwzlrdf3avrgzuyuozaiy