Perhydrotriphenylene‐based channel‐forming inclusion compounds (ICs) and thin films made of polyphenylenevinylene (PPV)‐type oligomers with terminal alkoxy groups are investigated and compared in a combined experimental and theoretical approach. Interchromophore interactions and host‐guest interactions are elucidated by UV/Vis and Raman spectroscopy. The impact of the local environment of the chromophore on the optical and photophysical properties is discussed in light of quantum‐chemical calculations. In stark contrast to thin films where preferential side‐by‐side orientation leads to quenching of photoluminescence (PL) via non‐emissive traps, the ICs are found to be attractive materials for opto‐electronic applications: they offer high chromophore concentrations, but at the same time behave as quasi‐isolated entities of tightly packed, well‐oriented objects with high PL quantum yields and the possibility of color tuning.

The triplet-triplet fluorescence spectra of a new carbene, 2,2-dinaphthylcarbene in n-hexane and n-heptane, were studied at cryogenic temperatures. Synthesis of the carbene precursor, 2,2-dinaphthyldiazomethane, is described. Spectral holes were burned within the inhomogeneous 0,0 fluorescence excitation line assigned to the pseudo-E/trans conformer. The complicated pattern of burned holes was interpreted with a model taking into account the zero-field splitting (ZFS) of the ground T 0 and excited T 1 triplet states and the selectivity of the intersystem crossing channel. The unusual observation of antiholes was attributed to the extremely long spin-lattice relaxation time in the T 0 state. The analysis provided direct information about the ZFS parameters of the T 0 and T 1 states: E 0 ) 0.022 ( 0.001 cm -1 , D 0 ) 0.477 ( 0.001 cm -1 , E 1 ) 0.006 ( 0.0002 cm -1 , and D 1 ) 0.043 ( 0.0005 cm -1 .

The triplet-triplet fluorescence and fluorescence excitation spectra of two new, planar diaryl carbenes in n-hexane and n-heptane were studied at cryogenic temperatures. Fluorescence decays were fitted to three exponential functions. Fluorescence decays of 12-oxo-5(12H)-naphthacenylidene were sensitive to the presence of a magnetic field, and this dependence allowed the estimation of the zero field splitting parameters (D) of the excited triplet state of this compound, which were 0.037 ( 0.010 and 0.03 ( 0.015 cm -1 for the low-and high-energy sites, respectively. These results are corroborated by computational studies of the ground-state preferences and the triplet excitation energies.

Spectral holes were burned within the inhomogeneous 0,0 fluorescence excitation lines of the T0 → T1 transition of 2,2-dinaphthylcarbene (2,2-DNC) in n-heptane at 1.7 K. The spectrum of holes, attributed to the Z/cis conformer of 2,2-DNC, was interpreted with a model taking into account the zero-field splitting (zfs) of both triplet states contributing to the transition, enforced C 2 v symmetry, and the dominance of internal conversion in the relaxation of the excited T1 state. Under enforced high symmetry, the number of possible electronic transitions between different spin sublevels of the ground T0 and excited T1 states is reduced and the analysis of spectral position of holes can only provide the differences between the zfs parameters:  D 0 − D 1 = 0.558 ± 0.001 cm-1 and E 0 − E 1 = 0.0183 ± 0.001 cm-1.