New functionalized phenylpyridine ligands and their derived heteroleptic cyclometalated Ir(III) complexes have been synthesized. The complexes possess a combination of important properties: (i) blue emission, (ii) good photoluminescence quantum yields, and (iii) good solubility in organic solvents, making them very attractive as phosphorescent dopant emitters for solution-processable light-emitting devices.
Current applications in porphyrin chemistry require the use of unsymmetrically substituted porphyrins. Many current industrial interests in optics and biomedicine require systems with either push-pull (electron donating and withdrawing groups) or amphiphilic systems (hydrophobic and hydrophilic groups). In this context we present the class of 5,10-A 2 B 2 -type porphyrins where two different substituents are positioned in diagonally opposite meso positions.Thus, the intramolecular dipole moment in these tetrapyrroles is positioned along a β−β vector passing through two pyrrole rings. This is opposite to the situation of the frequently used 5,15-A 2 BC porphyrins where the dipole moment is oriented along a meso-meso axis. We have elaborated syntheses of the 5,10-A 2 B 2 porphyrins using transition metal catalyzed transformations of 5,10-A 2 porphyrins or direct substitutions reactions thereof which give the target molecules in 22-77 % overall yield. The compounds exhibit interesting structural, spectroscopic and optical features and can serve as building blocks for new porphyrin arrays and applications.
Formylporphyrins were prepared by using either the 1,3-dithian-2-yl residue as a precursor for the CHO group or by the Vilsmeier reaction. Two synthetic routes for the introduction of the 1,2-dithian-2-yl group were explored. Furthermore, reactions of the 1,3,5-trithian-2-yl group with porphyrins were examined as well as spirobisdithiane derivatives as precursors for the ultimate assembly of porphyrin spirobisdithanyl-linked bioconjugates. The obtained formylporphyrins were reacted with organomagnesium or organophosphorus compounds. A series of hydroxyporphyrins resulting from the
A series of 3,7-bis(9,9-din -hexylfluoren-2-yl)-N-arylphenothiazine-S,S-dioxide trimers and (9,9-din -octylfluorene-2,7-diyl-coN -arylphenothiazine-S,S-dioxide) co-polymers, with varying ratios of phenothiazine-S,S-dioxide units, have been prepared in good yields by palladium-catalyzed cross-coupling reactions. The materials are deep blue emitters and show no solvatochromism or evidence for an intramolecular chargetransfer state. The photoluminescence quantum yields of the trimers are U PL 15-30% in solution and 14-25% in films. The polymers demonstrated very high values in solution (U PL 74-84%) and U PL values in films of 28-47%. The estimated HOMO energy levels are between À5.64 and À5.62 eV for the polymers with 15% incorporation of the phenothiazine-S,S-dioxide units. An analogous N-arylphenothiazine co-polymer shows significantly red shifted absorption and emission. Solution electrochemical data and density functional theory calculations are also presented. V
An investigation of the conformational landscape of 1,3-dithian-2-yl bearing porphyrins and the rotational behavior of the dithianyl substituents in meso position was carried out by variable-temperature (VT) NMR spectroscopy. Additionally, theoretical results for alternative conformations and energy barriers were obtained by molecular modeling. The study revealed different NH trans tautomers with regard to the orientation of the dithianyl ligands for the free base porphyrins 1-3. Relatively ruffled porphyrin core conformations were established for the transition states of the dithianyl rotation, resulting in a lower rotational energy barrier for the nickel(II) complex 4 compared to that of the free base systems. The data obtained and the first depiction of a rotational transition state for the rotation of bulky meso-alkyl substituents illustrate the close structural interplay between meso-alkyl substituents and the macrocycle conformation in porphyrins.
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