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Due to the low corrugation of the Au(111) surface, 1,4-bis(phenylethynyl)-2,5-bis(ethoxy)benzene (PEEB) molecules can form quasi interlocked lateral patterns, which are observed in scanning tunneling microscopy experiments at low temperatures. We demonstrate a multi-dimensional clustering approach to quantify the anisotropic pair-wise interaction of molecules and explain these patterns. We perform high-throughput calculations to evaluate an energy function, which incorporates the adsorption energy of single PEEB molecules on the metal surface and the intermolecular interaction energy of a pair of PEEB molecules. The analysis of the energy function reveals, that, depending on coverage density, specific types of pattern are preferred which can potentially be exploited to form one-dimensional molecular wires on Au(111).

The anticancer activity of titanium complexes has been known since the groundbreaking studies of Köpf and Köpf-Maier on titanocen dichloride. Unfortunately, possibly due to their fast hydrolysis, derivatives of titanocen dichloride failed in clinical studies. Recently, the new family of titanium salan complexes containing tetradentate ONNO ligands with anti-cancer properties has been discovered. These salan complexes are much more stabile in aqueous media. In this study we describe the biological activity of two titanium salan complexes in a mouse model of cervical cancer. High efficiency of this promising complex family was demonstrated for the first time in vivo. From these data we conclude that titanium salan complexes display very strong antitumor properties exhibiting only minor side effects. Our results may influence the chemotherapy with metallo therapeutics in the future.

A major goal of molecular electronics is the development and implementation of devices such as single‐molecular switches. Here, measurements are presented that show the controlled in situ switching of diarylethene molecules from their nonconductive to conductive state in contact to gold nanoelectrodes via controlled light irradiation. Both the conductance and the quantum yield for switching of these molecules are within a range making the molecules suitable for actual devices. The conductance of the molecular junctions in the opened and closed states is characterized and the molecular level E 0, which dominates the current transport in the closed state, and its level broadening Γ are identified. The obtained results show a clear light‐induced ring forming isomerization of the single‐molecule junctions. Electron withdrawing side‐groups lead to a reduction of conductance, but do not influence the efficiency of the switching mechanism. Quantum chemical calculations of the light‐induced switching processes correlate these observations with the fundamentally different low‐lying electronic states of the opened and closed forms and their comparably small modification by electron‐withdrawing substituents. This full characterization of a molecular switch operated in a molecular junction is an important step toward the development of real molecular electronics devices. Optical switching of single diarylethene molecule junctions. The first demonstration of a light‐induced transition to a high‐conductance state in a single‐molecule connected to gold electrodes is given. Full understanding of the current carrying molecular states and their coupling to the electrodes is achieved by analyzing the current–voltage characteristics of the junctions.

Diarylethene-derived molecules alter their electronic structure upon transformation between the open and closed forms of the diarylethene core, when exposed to ultraviolet (UV) or visible light. This transformation results in a significant variation of electrical conductance and vibrational properties of corresponding molecular junctions. We report here a combined experimental and theoretical analysis of charge transport through diarylethene-derived single-molecule devices, which are created using the mechanically controlled break-junction technique. Inelastic electron tunneling (IET) spectroscopy measurements performed at 4.2 K are compared with first-principles calculations in the two distinct forms of diarylethenes connected to gold electrodes. The combined approach clearly demonstrates that the IET spectra of single-molecule junctions show specific vibrational features that can be used to identify different isomeric molecular states by transport experiments.

We report on an experimental study of the charge transport through tunnel gaps formed by adjustable gold electrodes immersed into different solvents that are commonly used in the field of molecular electronics (ethanol, toluene, mesitylene, 1,2,4-trichlorobenzene, isopropanol, toluene/tetrahydrofuran mixtures) for the study of single-molecule contacts of functional molecules. We present measurements of the conductance as a function of gap width, conductance histograms as well as current–voltage characteristics of narrow gaps and discuss them in terms of the Simmons model, which is the standard model for describing transport via tunnel barriers, and the resonant single-level model, often applied to single-molecule junctions. One of our conclusions is that stable junctions may form from solvents as well and that both conductance–distance traces and current–voltage characteristics have to be studied to distinguish between contacts of solvent molecules and of molecules under study.

Eighteen novel Ti(IV) complexes stabilized by different chelating amino- bis (phenolato) (ONNO, ONON, ONOO) ligands and 2,6-dipicolinic acid as a second chelator were synthesized with isolated yields ranging from 79 to 93%. Complexes were characterized by 1 H and 13 C-NMR spectroscopy, as well as by HRMS and X-Ray diffraction analysis. The good to excellent aqueous stability of these Ti(IV) complexes can be modulated by the substitutions on the 2-position of the phenolato ligands. Most of the synthesized Ti(IV) complexes demonstrated potent inhibitory activity against Hela S3 and Hep G2 tumor cells. Among them, the naphthalenyl based Salan type 2j , 2-picolylamine based [ONON] type 2n and N -(2-hydroxyethyl) based [ONOO] type 2p demonstrated up to 40 folds enhanced cytotoxicity compared to cisplatin together with a significantly reduced activity against healthy AML12 cells. The three Ti(IV) complexes exhibited fast cellular uptake by Hela S3 cells and induced almost exclusively apoptosis. 2j could trigger higher level of ROS generation than 2p and 2n . Graphical abstract

Escherichia coli K-12 performs sulphoglycolysis; heterologous expression of enzymes encoded in a ten-gene cluster present in almost all (>91%) available E. coli genomes is used to show that sulphoquinovose is catabolised through four reactions to produce dihydroxyacetone phosphate, which powers energy conservation and growth, and a sulphonate product, which is excreted. Sulphoglycolysis as well as glycolysis in E. coli The monosaccharide sugar sulphoquinovose is a major component of the biological sulphur cycle, distributed widely in photosynthetic membranes and also in some non-photosynthetic bacteria and archaea. There is evidence for three different degradative pathways for sulphoquinovose in bacteria, but until now none had been fully characterized. This study shows that Escherichia coli K-12, the most widely-studied prokaryotic model organism, can perform sulphoglycolysis as well as standard glycolysis. A ten-gene cluster encodes all the enzymes needed to degrade sulphoquinovose to dihydroxyacetone phosphate. The same gene cluster is present in almost all available E. coli genomes and is widespread among the Enterobacteriaceae. The authors suggest that this newly defined pathway may represent a substantial part of the biogeochemical sulphur cycle, and may have a significant role in bacteria in the alimentary tract of all omnivores and herbivores, and in plant pathogens. Sulphoquinovose (SQ, 6-deoxy-6-sulphoglucose) has been known for 50 years as the polar headgroup of the plant sulpholipid 1 , 2 in the photosynthetic membranes of all higher plants, mosses, ferns, algae and most photosynthetic bacteria 3 . It is also found in some non-photosynthetic bacteria 4 , and SQ is part of the surface layer of some Archaea 5 . The estimated annual production of SQ 4 is 10,000,000,000 tonnes (10 petagrams), thus it comprises a major portion of the organo-sulphur in nature, where SQ is degraded by bacteria 6 , 7 . However, despite evidence for at least three different degradative pathways in bacteria 6 , 7 , 8 , no enzymic reaction or gene in any pathway has been defined, although a sulphoglycolytic pathway has been proposed 7 . Here we show that Escherichia coli K-12, the most widely studied prokaryotic model organism, performs sulphoglycolysis, in addition to standard glycolysis. SQ is catabolised through four newly discovered reactions that we established using purified, heterologously expressed enzymes: SQ isomerase, 6-deoxy-6-sulphofructose (SF) kinase, 6-deoxy-6-sulphofructose-1-phosphate (SFP) aldolase, and 3-sulpholactaldehyde (SLA) reductase. The enzymes are encoded in a ten-gene cluster, which probably also encodes regulation, transport and degradation of the whole sulpholipid; the gene cluster is present in almost all (>91%) available E. coli genomes, and is widespread in Enterobacteriaceae. The pathway yields dihydroxyacetone phosphate (DHAP), which powers energy conservation and growth of E. coli , and the sulphonate product 2,3-dihydroxypropane-1-sulphonate (DHPS), which is excreted. DHPS is mineralized by other bacteria, thus closing the sulphur cycle within a bacterial community.

Catalyst- and template-free condensation of photochromic difurylethene bisaldehyde with o-phenylenediamine led to selective formation of macrocyclic Schiff base [AB]2 product. Application of the same difurylethene bisaldehyde in the McMurry reaction resulted in cyclic dimer formation in moderate yield. No linear oligomers were observed in both approaches.

Abstract Sulfoquinovose (SQ, 6-deoxy-6-sulfoglucose) was synthesized chemically. An HPLC-ELSD method to separate SQ and other chromophore-free sulfonates, e.g. 2,3-dihydroxypropane-1-sulfonate (DHPS), was developed. A set of 10 genome-sequenced, sulfonate-utilizing bacteria did not utilize SQ, but an isolate, Pseudomonas putida SQ1, from an enrichment culture did so. The molar growth yield with SQ was half of that with glucose, and 1 mol 3-sulfolactate (mol SQ)−1 was formed during growth. The 3-sulfolactate was degraded by the addition of Paracoccus pantotrophus NKNCYSA, and the sulfonate sulfur was recovered quantitatively as sulfate. Another isolate, Klebsiella oxytoca TauN1, could utilize SQ, forming 1 mol DHPS (mol SQ)−1; the molar growth yield with SQ was half of that with glucose. This DHPS could be degraded by Cupriavidus pinatubonensis JMP134, with quantitative recovery of the sulfonate sulfur as sulfate. We presume that SQ can be degraded by communities in the environment.

Background Chemotherapy is one of the major treatment modalities for cancer. Metal-based compounds such as derivatives of cisplatin are in the front line of therapy against a subset of cancers, but their use is restricted by severe side-effects and the induction of resistance in treated tumors. Subsequent research focused on development of cytotoxic metal-complexes without cross-resistance to cisplatin and reduced side-effects. This led to the discovery of first-generation titanium(IV)salan complexes, which reached clinical trials but lacked efficacy. New-generation titanium (IV)salan-complexes show promising anti-tumor activity in mice, but their molecular mechanism of cytotoxicity is completely unknown. Methods Four different human cell lines were analyzed in their responses to a toxic (Tc52) and a structurally highly related but non-toxic (Tc53) titanium(IV)salan complex. Viability assays were used to reveal a suitable treatment range, flow-cytometry analysis was performed to monitor the impact of dosage and treatment time on cell-cycle distribution and cell death. Potential DNA strand break induction and crosslinking was investigated by immunostaining of damage markers as well as automated fluorometric analysis of DNA unwinding. Changes in nuclear morphology were analyzed by DAPI staining. Acidic beta-galactosidase activity together with morphological changes was monitored to detect cellular senescence. Western blotting was used to analyze induction of pro-apoptotic markers such as activated caspase7 and cleavage of PARP1, and general stress kinase p38. Results Here we show that the titanium(IV)salan Tc52 is effective in inducing cell death in the lower micromolar range. Surprisingly, Tc52 does not target DNA contrary to expectations deduced from the reported activity of other titanium complexes. Instead, Tc52 application interferes with progression from G2-phase into mitosis and induces apoptotic cell death in tested tumor cells. Contrarily, human fibroblasts undergo senescence in a time and dose-dependent manner. As deduced from fluorescence studies, the potential cellular target seems to be the cytoskeleton. Conclusions In summary, we could demonstrate in four different human cell lines that tumor cells were specifically killed without induction of major cytotoxicity in non-tumorigenic cells. Absence of DNA damaging activity and the cell-cycle block in G2 instead of mitosis makes Tc52 an attractive compound for further investigations in cancer treatment.