(3,5,5,6,8,8-Hexamethyl-5,6,7,8-tetra­hydro­naphthalen-2-yl)methanol: a possible metabolite of the synthetic musk fragrance AHTN

The title compound (AHTN-OH), C17H26O, was prepared in order to provide standard materials for the qualitative and quanti­tative analysis of environmental pollutants. The mol­ecule possesses a chiral C atom, although the structure determination was performed on racemic material, expressed in the structure as disordered chiral sites. The asymmetric unit consists of four AHTN-OH mol­ecules containing an hy­droxy group and forming a tetra­meric cyclic motif built up by four strong hydrogen bonds between these hy­droxy groups and additionally by two weak C—H⋯π inter­actions. Furthermore, these tetra­mers are linked via very weak C—H⋯π inter­actions, forming chains along the c axis

Pyrimidoquinazolinophenanthroline Opens Next Chapter in Design of Bridging Ligands for Artificial Photosynthesis **

The synthesis and detailed characterization of a new Ru polypyridine complex containing a heteroditopic bridging ligand with previously unexplored metal‐metal distances is presented. Due to the twisted geometry of the novel ligand, the resultant division of the ligand in two distinct subunits leads to steady state as well as excited state properties of the corresponding mononuclear Ru(II) polypyridine complex resembling those of prototype [Ru(bpy) 3 ] 2+ (bpy=2,2'‐bipyridine). The localization of the initially optically excited and the nature of the long‐lived excited states on the Ru‐facing ligand spheres is evaluated by resonance Raman and fs‐TA spectroscopy, respectively, and supported by DFT and TDDFT calculations. Coordination of a second metal (Zn or Rh) to the available bis‐pyrimidyl‐like coordination sphere strongly influences the frontier orbitals, apparent by, for example, luminescence quenching. Thus, the new bridging ligand motif offers electronic properties, which can be adjusted by the nature of the second metal center. Using the heterodinuclear Ru−Rh complex, visible light‐driven reduction of NAD + to NADH was achieved, highlighting the potential of this system for photocatalytic applications

Intracellular Photophysics of an Osmium Complex bearing an Oligothiophene Extended Ligand

This contribution describes the excited-state properties of an Osmium-complex when taken up into human cells. The complex 1 [Os(bpy)2(IP-4T)](PF6)2 with bpy=2,2′-bipyridine and IP-4T=2-{5′-[3′,4′-diethyl-(2,2′-bithien-5-yl)]-3,4-diethyl-2,2′-bithiophene}imidazo[4,5-f][1,10]phenanthroline) can be discussed as a candidate for photodynamic therapy in the biological red/NIR window. The complex is taken up by MCF7 cells and localizes rather homogeneously within in the cytoplasm. To detail the sub-ns photophysics of 1, comparative transient absorption measurements were carried out in different solvents to derive a model of the photoinduced processes. Key to rationalize the excited-state relaxation is a long-lived 3ILCT state associated with the oligothiophene chain. This model was then tested with the complex internalized into MCF7 cells, since the intracellular environment has long been suspected to take big influence on the excited state properties. In our study of 1 in cells, we were able to show that, though the overall model remained the same, the excited-state dynamics are affected strongly by the intracellular environment. Our study represents the first in depth correlation towards ex-vivo and in vivo ultrafast spectroscopy for a possible photodrug. © 2020 The Authors. Published by Wiley-VCH Gmb

Cross-π-conjugated enediyne with multioptic metal binding sites

Gefördert durch den Publikationsfonds der Universität Kasse

Localizing the initial excitation - A case study on NiO photocathodes using Ruthenium dipyridophenazine complexes as sensitizers

International audienceWe report on the localization of the initially excited electronic state within the molecular framework of a series of [Ru(bpy)(2)dppz](2+) derivatives (bpy:2,2'-bipyridine, dppz: dipyrido-phenazine) as sensitizers in NiO based photocathodes. The introduction of conjugated linkers with phenylene and triazole moieties in the bpy ligand sphere separates the NiO surface from the metal center and hence is considered to stabilize the charge separated state, which results from light-driven hole injection. However, introduction of the conjugated linkers also alters the localization of the excess electron density in the excited state within the ligand sphere and impacts the extent to which the charge-separated state is formed. The study emphasizes that tuning the ligand with the lowest-energy pi* orbital distal or proximal to the NiO surface significantly affects the initial charge-separation and the solar cell performance. The stability of the charge-separated state correlates with the observed photocurrents in dye-sensitized solar cells. Furthermore, the study challenges the widely accepted concept that the introduction of extended anchoring groups, i.e. increasing Ru - NiO distance, stabilizes the charge-separated state and suppresses charge recombination at the metal-oxide molecule interface

Anchoring Energy Acceptors to Nanostructured ZrO₂ Enhances Photon Upconversion by Sensitized Triplet–Triplet Annihilation Under Simulated Solar Flux

Photon upconversion by sensitized triplet–triplet annihilation (UC-STTA) is a promising strategy for boosting the theoretical maximum efficiency of single threshold solar cells, in particular, dye-sensitized solar cells (DSSCs). Here, we report a substantial increase in the efficiency of UC-STTA on a nanostructured surface, using noncoherent excitation light with intensities as low as 0.5 mW cm^–2, easily achieved under sun illumination. The studied surface was a mesoporous ZrO₂ film working as a proxy system for the study of photophysics relevant to DSSCs. A well-known UC-STTA “emitter” dye, 9,10-diphenylanthracene (DPA), was chemically modified to yield methyl 4-(10-<i>p</i>-tolylanthracen-9-yl)­benzoate (MTAB), which was chemisorbed onto ZrO₂. The “sensitizer” dye, platinum­(II) octaethylporphyrin (PtOEP), was free in butyronitrile (BuN) solution surrounding the ZrO₂ nanostructure. A rigorous oxygen removal minimized photodegradation of the dyes and enhanced triplet–triplet annihilation efficiency. The system already approaches the so-called “strong annihilation limit” at light intensities below 8 mW cm^–2. Highly efficient triplet–triplet annihilation is a requisite for the use of UC-STTA in DSSCs. Time-resolved data show that the limiting process in the UC-STTA mechanism of the present system is the dynamic triplet energy transfer step from PtOEP in solution to MTAB on the surface of ZrO₂. This result can guide the way toward a better understanding and further efficiency improvement of UC-STTA on nanocrystalline metal oxides