Modelling plexcitons of periodic gold nanorod arrays with molecular components.

Plasmonic or exciton/plasmon (plexcitonic) systems are presently described based on electromagnetic models, ignoring the need for an improved microscopic understanding. This is based on the fact that a full quantum mechanical approach on a micrometer scale still represents a considerable challenge. In this paper we report on the experimental observation of plexcitons in 2D gold nanorod array systems coupled to dye molecules and we provide a description of the experimental data using a quantum model. We show that treating the collective behavior in the array as being represented by a single quasiparticle is a suitable approximation that offers the opportunity to avoid the complicated calculation of long-distance interactions between the individual nanoparticles of the plexcitonic, periodic system. This enables us to model the optical response of plasmons in nanostructured arrays in contact with quantum emitters and to derive microscopic informations. Our work provides a potential tool for the design of plexcitonic devices, which rely on periodic metallic nanostructures.

Conformational dynamics of bis(BF2)-2,2'-bidipyrrins revealed by through-space 13C-19F and 19F-19F couplings.

The conformation of [bis-(N,N'-difluoroboryl)]-3,3'-diethyl-4,4',8,8',9,9',10,10'-octamethyl-2,2'-bidipyrrin (1) in solution was studied by analyzing the 13C-19F and 19F-19F through-space spin-spin couplings. The 1H and 13C NMR spectra were assigned on the basis of nuclear Overhauser effect spectroscopy (NOESY), heteronuclear single-quantum correlation (HSQC), and heteronuclear multiple-bond correlation (HMBC) experiments. The 19F spectrum of 1 was compared with that of 2-ethyl-1,3,5,6,7-pentamethyl-4,4-difluoro-4-bor-3a,4a-diaza-s-indacen (2). The 19F-19F through-space spin--spin coupling in 1 was thus assigned and the coupling constant was obtained by simulating the coupling patterns. The obtained conformation of 1 was compared with those of the known complexes [bis-(N,N'-difluoroboryl)]-3,3',8,8',9,9'-hexaethyl-4,4',10,10'-tetramethyl-6,6'-(4-methylphenyl)-2,2'-bidipyrrin (3)and [bis-(N,N'-difluoroboryl)]-9,9'-diethyl-4,4',8,8',10,10'-hexamethyl-3,3'-bis(methoxycarbonylethyl)-2,2'-bidipyrrin (4). The conformational dynamics of 1, 3, and 4 was surveyed by observing the temperature dependence of the through-space coupling constants between 253 and 333 K. The 13C-19F and 19F-19F through-space spin-spin couplings thus confirm similar conformations of different BisBODIPYs in solution in contrast to earlier findings in the solid state.

Manganese as a template: a new synthesis of corrole.

The reaction of 2,2'-bisdipyrrins 1, 2, and 3 with manganese(II) acetate tetrahydrate and molecular dioxygen yields the manganese(III)corroles 4, 5 and 6, which are readily demetalated to the respective free-base corroles.

Isoporphycene: The Fourth Constitutional Isomer of Porphyrin with an N(4) Core-Occurrence of E/Z Isomerism.

Liberation of the ligand from the nickel complex 1 obtained by template synthesis yielded isoporphycene (as the octaethyl derivative 2), the first constitutional isomer of porphyrin with an N(4) core for which E/Z isomerism is involved: Compound 2 is present as the E isomer, which is in rapid, presumably acid-catalyzed equilibrium with a small amount (2 %) of the Z isomer. The remaining unknown constitutional isomers of porphyrin are considerably higher in energy than the already rather labile isoporphycene, so that the latter should mark the border of existence for this type of structural variant of porphyrin.