In attempts at kinetically stabilizing blue-emissive anthracenes, a series of 9,10-diaryl substituted derivatives were tested for their photochemical and photooxidative persistence. A major breakthrough in light fastness comes from a new bis-meta-terphenylyl substituted anthracene which is much superior to industrially relevant 9,10biarylated anthracenes. The key issue is the steric shielding of the anthracene core. Further, intramolecular ring closure via Yamamoto coupling furnished a doubly bridged anthracene as a "self-encapsulated" sky-blue emitter which is most resistant to photodegradation. The improved stabilization was corroborated by time-resolved irradiation experiments and rationalized by X-ray crystallography.

The synthesis of unsubstitutedo ligo-para-phenylenes (OPP)e xceeding para-hexaphenylene-in the literature often referredt oasp-sexiphenyl-has long remained elusive due to their insolubility.W er eport the first preparationo f unsubstituted para-nonaphenylenes (9PPs) by extending our precursor route to poly-para-phenylenes(PPP)t oadiscrete oligomer.T wo geometric isomerso fm ethoxylated syn-a nd anti-cyclohexadienylenes were synthesized,f rom which 9PP was obtained via thermal aromatization in thin films. 9PP was characterized via optical,i nfrared and solid-state 13 CNMR spectroscopy as well as atomicf orce microscopy and mass spectrometry,a nd compared to polymeric analogues. Due to the lack of substitution, para-nonaphenylene, irrespectiveo ft he precursor isomer employed, displays pronounced aggregationi nt he solid state. Intermoleculare xcitonic coupling leads to formation of H-typea ggregates, redshiftinge mission of the films to greenish. 9PP allows to study the structure-property relationship of para-phenylene oligomers and polymers, especiallys ince the opticalp roperties of PPP depend on the molecular shapeo ft he precursor.

Chrysenea nd its bisbenzannulated homologue, naphtho[2,3-c]tetraphene,w ere synthesized through a PtCl 2-catalyzed cyclization of alkynes, which also furnished corresponding biaryls subsequentt oaGlaser couplingr eaction of the startinga lkynes.T he optoelectronic properties of 5,5'-bichrysenyl and 6,6'-binaphtho[2,3-c]tetraphene were compared to their chrysene-based "monomers". Oxidative cyclodehydrogenations of bichrysenyl andi ts higher homologue towardsl arge nanographenes were also investigated.