TY - JOUR A1 - Wang, Y.-W. A1 - Descalzo López, Ana Belén A1 - Shen, Z. A1 - You, X.-Z. A1 - Rurack, Knut T1 - Dihydronaphthalene-fused Boron-dipyrromethene (BODIPY) dyes: insight into the electronic and conformational tuning modes of BODIPY fluorophores JF - Chemistry - A European journal N2 - A new series of boron-dipyrromethene (BDP, BODIPY) dyes with dihydronaphthalene units fused to the β-pyrrole positions (1 a-d, 2) has been synthesised and spectroscopically investigated. All the dyes, except pH-responsive 1 d in polar solvents, display intense emission between 550-700 nm. Compounds 1 a and 1 b with a hydrogen atom and a methyl group in the meso position of the BODIPY core show spectroscopic properties that are similar to those of rhodamine 101, thus rendering them potent alternatives to the positively charged rhodamine dyes as stains and labels for less polar environments or for the dyeing of latex beads. Compound 1 d, which carries an electron-donating 4-(dimethylamino)phenyl group in the meso position, shows dual fluorescence in solvents more polar than dibutyl ether and can act as a pH-responsive "light-up" probe for acidic pH. Correlation of the pKa data of 1 d and several other meso-(4-dimethylanilino)-substituted BODIPY derivatives allowed us to draw conclusions on the influence of steric crowding at the meso position on the acidity of the aniline nitrogen atom. Preparation and investigation of 2, which carries a nitrogen instead of a carbon as the meso-bridgehead atom, suggests that the rules of colour tuning of BODIPYs as established so far have to be reassessed; for all the reported couples of meso-C- and meso-N-substituted BODIPYs, the exchange leads to pronounced redshifts of the spectra and reduced fluorescence quantum yields. For 2, when compared with 1 a, the opposite is found: negligible spectral shifts and enhanced fluorescence. Additional X-ray crystallographic analysis of 1 a and quantum chemical modelling of the title and related compounds employing density functional theory granted further insight into the features of such sterically crowded chromophores. KW - Dyes/pigments KW - Fluorescent probes KW - Photophysics KW - Protonation KW - Boron PY - 2010 DO - https://doi.org/10.1002/chem.200902527 SN - 0947-6539 SN - 1521-3765 VL - 16 IS - 9 SP - 2887 EP - 2903 PB - Wiley-VCH Verl. CY - Weinheim AN - OPUS4-20957 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Xu, H.-J. A1 - Mack, J. A1 - Descalzo López, Ana Belén A1 - Shen, Z. A1 - Kobayashi, N. A1 - You, X.-Z. A1 - Rurack, Knut T1 - meso-Aryl phenanthroporphyrins: Synthesis and spectroscopic properties JF - Chemistry - A European journal N2 - The successful synthesis of tetraphenyltetraphenanthroporphyrin (TPTPhenP; 5a) in 2006 under modified Rothemund–Lindsey conditions yielded a tetraphenyl porphyrinoid with a B band redshifted to an unprecedented 576 nm. Radially symmetric fused-ring expansion of tetraphenylporphyrin with phenanthrene moieties results in very deep saddling due to steric crowding and very marked redshifts of the Q and B (or Soret) porphyrinoid absorption bands. The extent to which the TPTPhenP structure can be further modified is explored, and the optical properties of TPTPhenPs are analyzed based on a perimeter model approach that makes use of time-dependent DFT calculations and magnetic circular dichroism spectroscopy and also based on a detailed analysis of the fluorescence emission. Attempts to introduce substituents at the ortho and meta positions of the meso-phenyl groups and to insert a central metal proved unsuccessful. The synthesis of a series of TPTPhenPs with strong electron-withdrawing (—CN, —NO2) and -donating (—CH3, —N(CH3)2) substituents at the para positions of the meso-phenyl rings is reported. Marked redshifts of the main spectral bands were consistently observed. The most pronounced spectral changes were observed with —N(CH3)2 groups (5i) due to a marked destabilization of the HOMO, which has large MO coefficients on the meso-carbon atoms. Protonation of 5i at both the ligand core and at the —N(CH3)2 groups resulted in unprecedented Q00 band absorption at wavelengths greater than 1200 nm. KW - Charge transfer KW - Circular dichroism KW - Dyes/pigments KW - Porphyrinoids KW - Protonation PY - 2011 DO - https://doi.org/10.1002/chem.201002596 SN - 0947-6539 SN - 1521-3765 VL - 17 IS - 32 SP - 8965 EP - 8983 PB - Wiley-VCH Verl. CY - Weinheim AN - OPUS4-24208 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -