Photochemical transformation of a cellulose biosynthesis inhibitor into phytoene desaturase inhibitors.

Mode of action studies showed that 5-methyl-N,N-bis[6-(trifluoromethyl)pyridin-3-yl]pyridin-2-amine (4), a representative from a new class of herbicidal tris-pyridyl amines, is an inhibitor of cellulose biosynthesis (CB). The compound undergoes an oxidative photocyclization, when exposed to UV-B light (300-340 nm) in the presence of oxygen, to give a new class of herbicidal pyrrolodipyridines. These compounds are potent inhibitors of the herbicide target enzyme phytoene desaturase and no longer inhibit CB.

A reversible fluorescent probe for monitoring Ag(I) ions.

Silver-containing nanomaterials are of interest for their antibiotic properties, for a wide range of applications from medicine to consumer products. However, much remains to be learnt about the degradation of such materials and their effects on human health. While most analyses involve measurement of total silver levels, it is important also to be able to measure concentrations of active free Ag(I) ions. We report here the preparation of a coumarin-based probe, thiocoumarin silver sensor 1 (TcAg1), that responds reversibly to the addition of silver ions through the appearance of a new fluorescence emission peak at 565 nm. Importantly, this peak is not observed in the presence of Hg(II), a common interferent in Ag(I) sensing. To establish the utility of this sensor, we prepared silver-doped phosphate glasses with demonstrated bactericidal properties, and observed the Ag(I) release from these glasses in solutions of different ionic strength. TcAg1 is therefore a useful tool for the study of the environmental and medical effects of silver-containing materials.

A ratiometric iron probe enables investigation of iron distribution within tumour spheroids.

Iron dysregulation is implicated in numerous diseases, and iron homeostasis is profoundly influenced by the labile iron pool (LIP). Tools to easily observe changes in the LIP are limited, with calcein AM-based assays most widely used. We describe here FlCFe1, a ratiometric analogue of calcein AM, which also provides the capacity for imaging iron in 3D cell models.

An iterative in silico and modular synthetic approach to aqueous soluble tercyclic α-helix mimetics.

Tercyclic scaffolds, designed to have improved synthetic accessibility and aqueous solubility, were evaluated as structural α-helix mimetics by using an iterative in silico approach. The synthesis of these tercyclic scaffolds was accomplished using a modular synthetic approach by employing functionalised methoxyphenyl units which were readily manipulated to allow the introduction of various nitrogen-based heterocycles. The ability of these scaffolds to mimic the key i, i + 3 and i + 7 residues of a polyalanine α-helix was ratified by in silico studies, X-ray crystallographic and NOESY analysis, and their aqueous solubility was measured by a kinetic turbidimetric method.

Di-µ(2)-methoxo-bis-{[µ-3,10,18,25-tetra-aza-penta-cyclo-[17.4.4.3.1.1]triconta-1(31),2,4(9),5,7,10,12,14,16(32),17,19(24),20,22,25,27,29-hexa-deca-ene-31,32-diolato]dizinc(II)} bis-(perchlorate) N,N-dimethyl-formamide disolvate.

The title compound, [Zn(4)(C(28)H(18)N(4)O(2))(2)(CH(3)O)(2)](ClO(4))(2)·2C(3)H(7)NO, is a C2 symmetric tetra-nuclear zinc(II) complex comprised of two [Zn(2)L](2+) units bridged by a pair of µ(2)-OMe ligands (where L is the doubly-deprotonated form of the macrocyclic dinucleating ligand derived from the [2 + 2] Schiff base condensation between 2-hy-droxy-benzene-1,3-dicarbaldehyde and 1,2-diamino-benzene). Each Zn(II) atom has a distorted square-pyramidal coordination geometry and the Zn(4)(µ-OMe)(2) unit lies in the cleft formed by two distinctly bent Schiff base ligands. The observed mol-ecular shape is supported by an intra-molecular π-π inter-action between one of the phenolate rings on each of the two ligands [centroid-centroid distance = 3.491 (5) Å]. The methyl groups of the solvent molecule are disordered over two sets of sites in a 0.6:0.4 ratio.