A family of heavy atom-free BODIPY-anthracene dyads (BADs) exhibiting triplet excited state formation from charge-transfer states is reported. Four types of BODIPY scaffolds, different in the alkyl substitution pattern, and four anthracene derivatives have been used to access BADs. Fluorescence and intersystem crossing (ISC) in these dyads depend on donor-acceptor couplings and can be accurately controlled by substitution or media polarity. Under conditions that do not allow charge transfer (CT), the dyads exhibit fluorescence with high quantum yields. Formation of charge-transfer states triggers ISC and the formation of long-lived triplet excited states in the dyads. The excited state properties were studied by steady-state techniques and ultrafast pump-probe spectroscopy to determine the parameters of the observed processes. Structural information for various BADs was derived from single crystal X-ray structure determinations alongside DFT molecular geometry optimization, revealing the effects of mutual orientation of subunits on the photophysical properties. The calculations showed that alkyl substituents on the BODIPY destabilize CT states in the dyads, thus controlling the charge transfer between the subunits. The effect of the dyad structure on the ISC efficiency was considered at the M06-2X level of theory, and a correlation between mutual orientation of the subunits and the energy gap between singlet and triplet CT states was studied using a multireference CASSCF method.

, et al. (2018) BODIPY-pyrene and perylene dyads as heavy atom-free singlet oxygen sensitizers. ChemPhotoChem.

Gold(I) complexes of ClickPhos [2.2]paracyclophane ligands were synthesized in excellent yields and fully characterized by spectroscopic methods as well as X-ray crystallography. The complexes exhibit a rigid ligand backbone and a triazolyl moiety and were systematically studied with respect to their cytotoxic properties. In combination with the ionic complex [(GemPhos)Au(tht)][ClO ] (tht=tetrahydrothiophene), in which the gold(I) atom exhibits a distorted trigonal coordination sphere of two phosphines and a labile tht ligand, their efficiency in cytotoxicity was investigated in HeLa, MCF7, and HCT116 cells as well as in a zebrafish model. Their cytotoxicity and their mechanisms of action are different and involve apoptosis, necrosis, and DNA damage. The compounds presented herein are potent metal-based cytostatics displaying LD values from 3.5-38 μm in different tumor cell lines and induce double-strand DNA breaks (DSB) as shown by H2AX phosphorylation (γH2AX) at foci of DSBs.

Three stable N,N’‐diarylated dihydroazaacene radical cations were prepared by oxidation of neutral N,N’‐diarylated dihydroazaacenes synthesized via palladium‐catalyzed Buchwald‐Hartwig aminations of aryl iodides with N,N’‐dihydroazaacenes. Both neutral as well as oxidized species were investigated via UV‐vis spectroscopy, single crystal analysis, and DFT calculations. All the radical cations are surprisingly stable—their absorption spectra in dichloromethane remain unchanged in ambient conditions for at least 24 hours.

Bis(silylethynylated) 5,7‐ and 5,12‐diazapentacenes were synthesized from cis‐ and trans‐quinacridone using protection, alkynylation and deoxygenation. The solid‐state packing of the targets is determined by choice and position of the silylethynyl substituents. The position of the substituents and nitrogen atoms influence the optical properties of the targets.