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The widely established PET isotope 18 F does not have a therapeutic partner. We have recently established that the Sc-F bond can be formed under aqueous, high yielding conditions, paving the way to providing 18 F as diagnostic partners to 47 Sc and 177 Lu radiotherapeutics. Here, we synthesized a library of tacn-based chelators comprised of 10 structurally unique permutations incorporating acetate, methyl-benzylamide and picolinate donor arms. The chelator library encompasses chelators ranging from 6- to 9-dentate, and produces complex changes ranging from +3 to -1. The corresponding Sc-F/Sc and Lu chelate complexes were characterized using computational, spectroscopic and potentiometric methods, followed by optimization of radiolabeling with 18 F, 44 Sc and 177 Lu and concluded by in vivo validation. We identify characterization benchmarks that chart the coordinative landscape of radiochelation approaches for this unusual triad. Our screening identifies two ligand systems, H 2 L 111 and H 3 L 201 as ideal, readily functionalizable constructs for prospective, targeted theranostic applications with 18 F/ 44 Sc/ 177 Lu., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Transition metal-catalyzed asymmetric nitrene transfer is a powerful method to generate enantioenriched amines found in natural products and bioactive molecules. A highly chemo- and enantioselective intramolecular silver-catalysed aziridination of 2,2,2-trichloroethoxysulfonyl (Tces)-protected carbamimidates gives [4.1.0]-bicyclic aziridines in good yields and up to 99% ee.

1,2-Bis{(3,5-dimethylpyrazol-1-yl)methyl}benzene (L) reacts with [Cu(OAc) 2 ] and C 6 H 5 COOH, 4-OH-C 6 H 4 COOH, 2-Cl-C 6 H 4 COOH and (3,5-NO 2 ) 2 -C 6 H 3 COOH to afford the copper complexes [Cu 2 (C 6 H 5 COO) 4 (L) 2 ] (1), [Cu 2 (4-OH-C 6 H 4 COO) 4 (L) 2 ] (2), [Cu 2 (2-Cl-C 6 H 4 COO) 4 (L) 2 ] n (3) and [Cu{(3,5-NO 2 ) 2 -C 6 H 3 COO} 2 L] n (4) which are characterised by IR, mass spectrometry, elemental analyses, and X-ray crystallography. The structural data revealed two geometries that are adopted by the complexes: (i) paddle wheel in 1, 2·7H 2 O, 3 and (ii) regular chains in 3 and 4. Magnetic studies show strong antiferromagnetic couplings in the paddle wheel complexes and a weak antiferromagnetic coupling in the monometallic chain one. Catalysis studies performed with these complexes (1-4) showed that they initiate ring opening polymerization (ROP) of ε-caprolactone (ε-CL) under solvent-free conditions and d,l-lactide in toluene at elevated temperatures. Polycaprolactone (PCL) and poly(d,l-lactide) (PLA) obtained from the polymerization reactions are of low molecular weights (858 for PCL and 602 Da for PLA for initiator 1) and polydispersity indices (typically 2.16 for PCL and 1.64 for PLA with 1 as the initiator). End group analysis of the polymers, determined by MALDI-ToF MS, indicates that the polymers have benzoate, hydroxyl, methoxy and cyclic end groups., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Conjugate addition of thiols to benzoquinones has been coupled to in situ electrochemical oxidation of the resulting hydroquinone to enable full substitution of quinone C-H bonds. The sulfonated thioether-substituted quinones exhibit high solublity and stability in aqueous solution and have redox potentials ranging from 440-750 mV vs. SHE. The electrosynthetic protocol is effective on >100 g scale.

An efficient four-step, six-transformation protocol was developed to afford bioactive N-alkyl- or N-arylamide (E)-arylamidines featuring strategic amidine C3 modifications which were inaccessible or low yielding by previous methods. This synthetic approach, exemplified with 24 amidines and requiring only a single purification, highlights a multicomponent Ugi-Mumm rearrangement to afford highly diversified quinazolinones which undergo regiospecific rearrangement to afford new amidines. The method extensively broadens the structural scope of this new class of trisubstituted amidines and demonstrates the tolerance of regional C3 amidine steric bulk, visualized with X-ray crystallographic analysis.

Three ring-shaped AEE-active silole-containing compounds were synthesized by mild condensation reactions. Cyclotrisiloxane compound 1 displays high solid-state quantum yield (Φfl = 0.86) with the fluorescence maximum at 512 nm. This high fluorescence efficiency results mainly from decreased vibrational pathways to fluorescence decay due to the intramolecular C-H···π interactions.

Various highly substituted 2,3'-diindolylmethane heterocycles were prepared from propargylic alcohols and indole nucleophiles via a transition metal-catalyzed tandem indole annulation/arylation reaction for the first time. Among the metal catalysts we examined, the most economical copper(I) catalyst provided the highest efficiency. The indole nucleophiles could also be replaced by other electron-rich arenes or alcohols.

The reaction of 2-{[2-(1H-imidazol-4-yl)-ethylimino]-methyl}-phenol (L1), 2,4-di-tert-butyl-6-{[2-(1H-imidazol-4-yl)-ethylimino]-methyl}-phenol (L2) or 4-tert-butyl-2-{[2-(1H-imidazol-4-yl)-ethylimino]-methyl}-phenol (L3) with iron(ii) precursors produced either iron(ii) or iron(iii) complexes, depending on the nature of the anions in the iron(ii) precursor and the ligand. When the anion is chloride and the ligand L1, the product is [(L1)2Fe][FeCl4] (1), but when the anion is triflate (OTf(-)) and the ligand is L2, the product is [(L2)2Fe][OTf]2 (2). With iron(ii) halides and tert-butyl groups on the phenoxy ligands L2 and L3, the iron(iii) complexes [(L2)FeX2] {where X = Cl (3), Br (4) and I = (5)} and [(L3)FeCl2] (6) were formed. Complexes 1-6 were characterised by a combination of elemental analyses, IR spectroscopy and mass spectrometry; and in selected cases (3 and 4) by single crystal X-ray crystallography. The crystal structures of 3 and 4 indicated that the iron(ii) precursors oxidised to iron(iii) in forming complexes 3-6; an observation that was corroborated by the magnetic properties and the (57)Fe Mössbauer spectra of 3 and 4. The iron(iii) complexes 3-6 were used as pre-catalysts for the oligomerisation and polymerisation of ethylene. Products of these ethylene reactions depended on the solvent used. In toluene ethylene oligomerised mainly to 1-butene and was followed by the 1-butene alkylating the solvent to form butyl-toluenes via a Friedel-Crafts alkylation reaction. In chlorobenzene, ethylene oligomerised mainly to a mixture of C4-C12 alkenes. Interestingly small amounts of butyl-chlorobenzenes and hexyl-chlorobenzenes were also formed via a Friedel-Crafts alkylation with butenes and hexenes from the oligomerisation of ethylene.

Reactions of [PdCl2(NCMe)2] with the ferrocenylpyrazolyl compounds: 3-ferrocenyl-1H-pyrazole-5-carboxylate (L1), ethyl-1-(2-bromoethyl)-3-ferrocenyl-1H-pyrazole-5-carboxylate (L2a), ethyl-1-(2-bromoethyl)-5-ferrocenyl-1H-pyrazole-3-carboxylate (L2b), 3-ferrocenylpyrazolyl-methylenepyridine (L3) and 3-ferrocenyl-5-methylpyrazolyl-methylenepyridine (L4) at room temperature afforded [PdCl2(L1)] (1), [PdCl2(L2a)] (2a), [PdCl2(L2b)] (2b), [PdCl2(L3)] (3) and [PdCl2(L4)] (4) respectively. Compounds L1-L4 and their palladium complexes were obtained in moderate to high (50-90%) yield and characterized by NMR spectroscopy, elemental analysis, and in selected cases by single crystal X-ray crystallography. Complexes 1-4 were used as pre-catalysts for the reactions of 1-heptene and 1-octene with EtAlCl2 as a co-catalyst. The activities of 1, 2a and 3b were relatively low (10 083-18 250 g molPd(-1) h(-1)) with 1-heptene being a better monomer for these complexes. However, pre-catalysts 3 and 4 showed moderate activities (123 000-448 000 g molPd(-1) h(-1)) 1-octene being the better monomer. The polyolefins obtained were characterized by both (1)H and (13)C{(1)H} NMR to be highly branched polyolefins with degree of branching up to 270 branches per 1000 carbon atoms. However, low molecular weights between 888 and 1198 were recorded with narrow PDI between 1.02 and 1.44.

αβα-Tripeptide that contains a cyclic β-amino acid with an eight-membered ring, a cis-2-aminocyclooct-5-enecarboxylic acid (cis-ACOE) or a cis-2-aminocyclooctanecarboxylic acid (cis-ACOC) displayed an 11/9-helical turn in the crystal state. The related α/β-peptide oligomers were shown to adopt 11/9-helical conformations in solution.

A Rh-catalyzed 1,3-acyloxy migration of propargyl ester followed by intramolecular [4+2] cycloaddition of vinylallene and unactivated alkyne was developed. This tandem reaction provides access to bicyclic compounds containing a highly functionalized isotoluene or cyclohexenone structural motif, while only aromatic compounds were observed in related transition metal-catalyzed cycloadditions., (This journal is © The Royal Society of Chemistry 2012)

We have resolved the enantiomers of a series of chiral modified metallophthalocyaninato complexes of nickel bearing alkoxy groups at the 14 and 28 positions on what would otherwise be a normal phthalocyaninato ligand and conforming to the general formula [14,28-(RO)(2)Pc]Ni(ii), where R = Me, Et, or n-Pr. The complex for which R = n-Pr is reported here for the first time. Resolution of the enantiomers of these complexes was accomplished via HPLC utilizing an immobilized carbohydrate-based stationary phase, resulting in baseline resolution of peaks corresponding to enantiomers of the complexes, with R(s) values in excess of five. Isolation of milligram quantities of the complexes bearing methoxy and n-propoxy groups in high enantiomeric excess has been achieved via semi-preparative-scale HPLC on the same stationary phase. Resolved samples of these compounds do not appear to racemize at an appreciable rate, nor do they readily exchange alkoxy groups with alcohols while stirring in alcoholic solution. The spectroscopic details and the crystallographically-determined solid-state structure for the complex where R = n-Pr are reported, and are highly similar to those that have been observed for the previously reported analogues. It has been shown by NMR that the chirality and C(2) molecular symmetry of the complex bearing n-propoxy groups is maintained in solution.

The para-aminobiphenyl compound [(η(6)-C(6)H(5))(C(6)H(4)-4-NH(2))]Cr(CO)(3) (1) has an arene-phenyl dihedral angle of 38.01(6)°, as determined by single-crystal X-ray crystallography, and 34.7(11)°, as determined by DFT calculations. It undergoes haptotropic rearrangement at 140 °C in solution to form [(η(6)-C(6)H(4)-4-NH(2))(C(6)H(5))]Cr(CO)(3) (2), even though previous reports have suggested that such rearrangements should not be observed in compounds with arene-phenyl dihedral angles greater than 22°. NMR analysis gave a rate constant of k = 5.0 × 10(-5) s(-1) for the rearrangement of 1 to 2. The ortho-substituted analog [(η(6)-C(6)H(5))(C(6)H(4)-2-NH(2))]Cr(CO)(3) (3) has an arene-phenyl dihedral angle of 67.70(7)°, as determined by single-crystal X-ray crystallography, and 51.9(10)°, as determined by DFT calculations. Surprisingly, even though it displays a more extreme canting of arene rings, 3 rearranges to [(η(6)-C(6)H(4)-2-NH(2))(C(6)H(5))]Cr(CO)(3) (4) at 140 °C in solution with a rate constant of k = 2.6 × 10(-4) s(-1). This approximately five-fold rate enhancement likely results from the ortho-amino group providing intramolecular stabilization for intermediates formed during the rearrangement.

Photocatalytic reactions of enones using metal polypyridyl complexes proceed by very different reaction manifolds in the presence of either Lewis or Brønsted acid additives. Previous work from our lab demonstrated that photocatalytic [2+2] cycloadditions of enones required the presence of a Lewis acidic co-catalyst, presumably to activate the enone and stabilize the key radical anion intermediate. On the other hand, Brønsted acid activators alter this reactivity and instead promote reductive cyclization reactions of a variety of aryl and aliphatic enones via a neutral radical intermediate. These two distinct reactive intermediates give rise to transformations differing in the connectivity, stereochemistry, and oxidation state of their products. In addition, this reductive coupling method introduces a novel approach to the tin-free generation of β-ketoradicals that react with high diastereoselectivity and with the high functional group compatibility typical of radical cyclization reactions.

A chiral seven-membered N-heterocyclic carbene (NHC) has been synthesized from its phenol adduct (NHC-HOPh) by a novel base-induced alpha-elimination method, and its donor strength has been determined from the IR stretching frequencies of the NHC-Rh(CO)(2)Cl complex.

A range of new alkylpyridinium and imidazolium carborane salts with [nido-C(2)B(9)H(12)](-), [closo-CB(11)H(12)](-), and [RC(2)B(11)H(11)](-) (R = methyl or butyl) anions have been prepared and characterized by physical and thermal methods, including the solid state structures of five of the salts determined by single crystal X-ray diffraction. The tendency of the salts to form low-melting ionic liquids has been assessed; all the salts studied with [nido-C(2)B(9)H(12)](-) anions melted below 100 degrees C and, significantly, have melting points that are 25-85 degrees C lower than those of the corresponding [closo-CB(11)H(12)](-) analogs, demonstrating that a wider range of boron-rich ionic liquid materials can be readily accessed.

An improved algorithm has been designed to characterize ligand interactions in organometallic and coordination complexes in terms of the percentage of the metal coordination sphere shielded by a given ligand. The computations for ligand solid angles are performed numerically and employ introduced atomic radii that are larger than covalent but smaller than van der Waals radii. This approach enables facile evaluation of steric congestion in the metal coordination sphere, quantification of unfavorable interligand contacts, and in some cases prediction of the complex composition or ligand coordination on purely geometrical grounds.

Solvothermal reactions of iron(II) acetate tetrahydrate and cobalt(II) acetate tetrahydrate with 1,2-dicyanobenzene in methanol solution result in the formation of racemic six-coordinate iron(III) and cobalt(III) complexes, respectively, with a new bicyclic pentadentate 14,28-[1,3-diiminoisoindolinato]phthalocyaninato ligand.

A new product implicated in cereal grain polysaccharide cross-linking has been authenticated by independent synthesis. Saponification of cereal grain fiber releases the RRRS/SSSR-isomer of 2,5-bis-(4-hydroxy-3-methoxyphenyl)-tetrahydrofuran-3,4-dicarboxylic acid. The parent ester logically derives from 8-8-coupling of ferulate followed by water addition to one of the incipient quinone methide moieties and internal trapping of the other. The finding adds complexity to the analysis of plant cell wall cross-linking, but provides clues to important polysaccharide cross-linking pathways occurring in planta.

Significant improvement of complexation of a bisparaquat guest was achieved by the formation of a pseudocryptand-based [3]pseudorotaxane.