This manuscript reports the synthesis and photophysical investigation of two hexa-peri-hexabenzocoronenes (HBCs) that are functionalized with platinum(II) acetylide units of the type trans-(Ar-CC-)2Pt(PBu3)2. In one complex, the platinum is directly linked to the HBC chromophore by an ethynyl spacer, whereas in the second, the platinum is separated from the HBC via a 1,4-phenylene ethynylene spacer. The Pt-acetylide units introduce strong spin-orbit coupling into the HBC chromophore, giving rise to high yields of the triplet excited state along with moderately intense phosphorescence at ambient temperature. On the basis of emission spectroscopy, the triplet state of the HBC chromophore is located at 2.14 eV and the S-T splitting is 0.6 eV. The triplet-triplet absorption and radical cation absorption spectra of the Pt-HBCs are determined by laser flash photolysis. Aggregation of the Pt-HBCs in a poor solvent such as hexane leads to quenching of the triplet state, but spectroscopy provides no evidence for the formation of a triplet excimer, even under conditions where the molecules are strongly aggregated.

A comprehensive photophysical study has been carried out on the two complexes [(bpy) 2 Ru(4,4′-PE-bpy)] 2+ and [(bpy) 2 Ru(5,5′-PE-bpy)] 2+ (44Ru and 55Ru, respectively, where bpy ) 2,2′-bipyridine and PE ) phenyleneethynylene). The objective of this work is to determine the effect of the phenyleneethynylene substituents on the properties of the metal-to-ligand charge-transfer excited state. The complexes have been characterized by using UV-visible absorption, photoluminescence, and UV-visible and infrared transient absorption spectroscopy. The results indicate that the MLCT excited state is localized on the PE-substituted bpy ligands. Moreover, the photophysical data indicate that in the MLCT excited state the excited electron is delocalized into the PE substituents and the manifestations of the electronic delocalization are larger when the substituents are in the 4,4′-positions.

The feedback control system to control plasma current and position on the HT-7 superconducting tokamak was greatly improved in early 1998. Lower hybrid current drive (LHCD) experiments with the improved control system were performed to sustain long pulse discharges and to improve plasma confinement. Partial non-inductive current drive and full non-inductive current drive for several seconds by means of LHCD were demonstrated. It was observed that plasma confinement could be considerably improved by LHCD. Experimental evidence suggests that this improvement during the LHCD phase could be due to the modification of the current profile in the outer region of the plasma. MHD modes (especially m = 2) seem unstable with such a current profile. The EFIT code was modified for the reconstruction of the magnetic surfaces in HT-7 and a test computation was performed.