An ovel core-shell structured columnar liquid crystal composed of ad onor-acceptor dyad of tetraphenoxy perylene bisimide (PBI), decorated with four bithiophene units on the periphery,w as synthesized.T his molecule self-assembles in solution into helical J-aggregates guided by p-p interactions and hydrogen bonds which organizei nto al iquid-crystalline (LC) columnar hexagonal domain in the solid state.D onor and acceptor moieties exhibit contrasting exciton coupling behavior with the PBIs (J-type) transition dipole moment parallel and the bithiophene side arms (Htype) perpendicular to the columnar axis.T he dyad shows efficient energy and electron transfer in solution as well as in the solid state.T he synergy of photoinduced electron transfer (PET) and charge transport along the narcissistically selfassembled core-shell structure enables the implementation of the dye in two-contact photoconductivity devices giving rise to a20-fold increased photoresponse compared to areference dye without bithiophene donor moieties.

Donor−acceptor dyads consisting of perylene bisimide (PBI) and trialkoxyphenyl−oligothiophene (TAPOT) units are reported that self-assemble into helical four-, six-, and seven-stranded hydrogen-bonded supramolecular polymers in solution and the columnar liquid-crystalline state. It is shown that the number of closely stacked and J-coupled PBI strands can be controlled by the incremental extension of the TAPOT wedge units in the bay position and the thereby tailored steric demand. Narcissistic self-sorting of TAPOT donor and PBI acceptor subunits facilitates the formation of core−shell structures creating individual percolation pathways for one-dimensional (1D) transport of photogenerated charge carriers. Macroscopic alignment of the nanoscale columnar structures by solution shearing enables anisotropic photoconductivity. Thus, selective orientation of the 1D charge-transporting domains parallel and perpendicular to the electrodes gives rise to an up to 90-fold increased photoresponse depending on the alignment quality. The intrinsic charge-separation and -transport properties were investigated by femtosecond transient absorption spectroscopy and flash-photolysis time-resolved microwave conductivity. These studies reveal a rising propensity for charge separation and transport upon increasing the conjugation length of the TAPOT donor and thereby increasing the size of the individual percolation pathways. Contrasting observations for intrinsic and macroscopic photoconductivities demonstrate the importance of processability in device performance.

Cauliflower Orange (Or) mutant is characterized by high level of b-carotene in its curd. Or mutation affects the OR protein that was shown to be involved in the posttranslational control of phytoene synthase (PSY), a major rate-limiting enzyme of carotenoid biosynthesis, and in maintaining PSY proteostasis with the plastid Clp protease system. A transposon integration into the cauliflower wild-type Or gene (BoOR-wt) results in the formation of three differently spliced transcripts. One of them is characterized by insertion (BoOR-Ins), while the other two have exon-skipping deletions (BoOR-Del and BoOR-LD). We investigated the properties of individual BoOR variants and examined their effects on carotenoid accumulation. Using the yeast split-ubiquitin system, we showed that all variants were able to form OR dimers except BoOR-LD. The deletion in BoOR-LD eliminated the first of two adjacent transmembrane domains and was predicted to result in a misplacement of the C-terminal zinc finger domain to the opposite side of membrane, thus preventing OR dimerization. As interaction with PSY is mediated by the N-terminus of BoOR, which remains unaffected after splicing, all BoOR variants including BoOR-LD maintained interactions with PSY. Expression of individual BoOR mutant variants in Arabidopsis revealed that their protein stability varied greatly. While expression of BoOR-Del and BoOR-Ins resulted in increased BoOR protein levels as BoOR-wt, minimal amounts of BoOR-LD protein accumulated. Carotenoid accumulation showed correlated changes in calli of Arabidopsis expressing these variants. Furthermore, we found that OR also functions in E. coli to increase the proportion of native, enzymatically active PSY from plants upon co-expression, but not of bacterial phytoene synthase CrtB. Taken together, these results suggest that OR dimerization is required for OR stability in planta and that the simultaneous presence of PSY interaction-domains in both OR and PSY proteins is required for the holdase function of OR. The more pronounced effect of simultaneous expression of all BoOR variants in cauliflower Or mutant compared with individual overexpression on carotenoid accumulation suggests an enhanced activity with possible formation of various BoOR heterodimers.

Water-soluble multinuclear complexes based on ruthenium 2,2'-bipyridine-6,6'-dicarboxylate (bda) and ditopic bipyridine linker units are investigated in three-component visible light-driven water oxidation catalysis. Systematic studies revealed a strong enhancement of the catalytic efficiency in the absence of organic co-solvents and with increasing oligomer length. In-depth kinetic and morphological investigations suggest that the enhanced performance is induced by the self-assembly of linear Ru(bda) oligomers into aggregated superstructures. The obtained turnover frequencies (up to 14.9 s À 1 ) and turnover numbers (more than 1000) per ruthenium center are the highest reported so far for Ru(bda)-based photocatalytic water oxidation systems.