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Novel macrocyclic bis[ruthenium(II)bipyridyl] and ruthenium(II) bipyridyl-metallocene receptors are prepared and shown by 1H NMR and fluorescence emission spectroscopy to exhibit remarkable selectivity for the chloride anion in preference to dihydrogen phosphate.

New upper-rim bis[rhenium(I) bipyridyl, ruthenium(II) bis(bipyridyl), cobaltocenium]calix[4]arene receptors exhibit remarkable dihydrogen phosphate selective anion recognition properties dictated by the relative positions of lower-rim tosyl substituents.

Investigations to exploit the anion binding induced conformational changes displayed by a new class of acyclic receptor for anion recognition, fluorescence sensing and pseudorotaxane disassembly are described. A series of imidazolium-appended bis-amide-pyridine, pyridine N-oxide and pyridinium containing receptors are synthesised and their anion binding properties elucidated using (1)H NMR spectroscopy. Upon anion recognition, the receptors exhibit a substantial conformational change from an 'open' to a more 'closed' intramolecular geometry. The fluorescence anion sensing ability of a bis-pyrene-functionalised analogue is investigated, with anion-induced responses arising from excimer signalling mechanisms. A pseudorotaxane assembly formed between the pyridine N-oxide receptor acting as a threading component and an isophthalamide macrocycle is demonstrated to undergo disassembly resulting from the conformational behaviour exhibited by the thread upon chloride binding.

Enantiospecific syntheses of furo[f]indolizines with different degrees of unstauration (4a,b, 8a, 9a, and 10a) as analogues of phenanthro[f]indolizidine alkaloids have been completed from (S)-glutamic acid in a few-step sequence. This was achieved from the known optically active alcohol-lactams 2a and 2b by utilizing chemical and catalytic reduction processes. During these transformations, we have shown that partial furan ring reduction can be achieved conveniently. The resulting products 5a and 8a readily constituted platforms to access stereoselectively the partially 6a and 7a or totally 9a and 9b reduced furo[f]indolizines. The key step of the stereocontrolled reduction seems to be the catalytic hydrogenation of the furan nucleus in the (4aS,9aS)-(+)-5a product. Assignments of the absolute stereochemistry are made and some mechanistic aspects of these transformations also discussed.

The synthesis of a series of calix[4]arene ligands bearing lower rim 1,3-acid-amide functionality for the two-phase solvent extraction of lanthanide and uranyl ions from aqueous wastes is described. X-Ray crystal structure studies demonstrate binding of lanthanide ions at the calixarene lower rim through phenolate, carboxylate and carboxamide oxygen atoms. The crystal structures of a centrosymmetric, dimeric lanthanum(III) and non-centrosymmetric dimeric sodium(I) complexes of a 1,3-acid-dihexylamidecalix[4]arene ligand are detailed. Electrospray mass spectrometry confirms retention of this 2 ∶ 2 dimeric structure for large lanthanide ions and that the smaller lanthanide ions e.g. Lu3+ form monomeric 1 ∶ 1 calixarene ∶ lanthanide complexes in solution. Extraction studies demonstrate a pH dependent uptake of lanthanide and uranyl cations by 1,3-acid-amide ligands with the nature of the carboxamide substituent largely irrelevant to extraction efficiency. Upper rim modified 1,3-dinitro and de-tert-butylcalix[4]arene ligands were prepared and NMR and ES-MS studies confirm uranyl coordination by these novel acid-amide ligands. The 1,3-dinitro and de-tert-butyl ligands exhibit superior and more efficient extraction of uranyl cations at lower pH values.

The furo[2,3(or 3,2)-f]indolizidinediones 4a,b were synthesized in five steps from glutamic acid in good yield. The ketones were converted into trans alcohols 5a,b or oximes 6a,b (either as syn-anti mixture or as single isomer). The selectivity of these reactions is discussed.

The Lewis acidic redox-active and photoactive ruthenium(II) bipyridyl moiety in combination with amide (CO-NH) groups has been incorporated into acyclic, macrocyclic, and lower rim calix[4]arene structural frameworks to produce a new class of anion receptor with the dual capability of sensing anionic guest species via electrochemical and optical methodologies. Single-crystal X-ray structures of (1)Cl and (11)H2PO4 reveal the importance of hydrogen bonding to the overall anion complexation process. In the former complex, six hydrogen bonds (two amide and four C-H groups) stabilize the Cl- anion and three hydrogen bonds (two amide and one calix[4]arene hydroxyl) effect H2PO4 - complexation with 11. Proton NMR titration investigations in deuterated DMSO solutions reveal these receptors form strong and, in the case of the macrocyclic 5 and calix[4]arene-containing receptor 11, highly selective complexes with H2PO4 -. Cyclic and square-wave voltammetric studies have demonstrated these receptors to electrochemically recognize Cl-, Br-, H2PO4 -, and HSO4 - anions. The calix[4]arene anion receptor 11 selectively electrochemically senses H2PO4 - in the presence of 10-fold excess amounts of HSO4 - and Cl-. Fluorescence emission spectral recognition of H2PO4 - in DMSO solutions is displayed by 3, 5, and 11.

The synthesis of calix[4]arene based dendrimers containing up to seven calix[4]arene moieties is described, including the X-ray crystal structure of a tris-calix[4]arene branching derivative.

Nucleophilic addition of alkyl-, cycloalkylamines, or saturated nitrogen-containing heterocycles to isolated or in situ generated 6-(2,3-epoxypropyl)-5,6,7,8-tetrahydrodibenz[c,e]azocine (III) afforded 6-(3-substituted amino-2-hydroxypropyl)-5,6,7,8-tetrahydrodibenz[c,e]azocines IV and their hydrochlorides. The starting 5,6,7,8-tetrahydrodibenz[c,e]azocine (I) reacted with 1-chloro-2,3-epoxypropane to yield 6-(3-chloro-2-hydroxypropyl)-5,6,7,8-tetrahydrodibenz[c,e]azocine (II), which, on treatment with sodium ethoxide or an excess of an amine eliminated hydrogen chloride to give the intermediate III.

Guanidine derivatives of 5,6,7,8-tetrahydrodibenz[c,e]azocine IV and V were prepared by a three-step synthesis starting from 5,6,7,8-tetrahydrodibenz[c,e]azocine (I) via the corresponding 6-(ω-cyanoalkyl) II and 6-(ω-aminoalkyl) derivatives III; finaly, compounds III were treated with either methylisothiuronium halide or methylthioimidazolinium halide.

3,7-Dialkyl-8-alkyl- or -aryl-3,7-dihydropurine-2,6-diones XII-XIV were synthesized from 5-alkylamino-6-amino-1-alkyl-2,4(1H,3H)-pyrimidinediones VII-IX by three methods: the first is based upon an acid catalyzed cyclization of the starting derivatives VII-IX with orthoesters of carboxylic acids in dimethylformamide. In the second and third methods the 5-((N-acyl)(N-alkyl)amino) derivatives X, XI, obtained by acylation of VII-IX were cyclized either in aqueous solution of alkali metal hydroxides, or in dimethylformamide in the presence of alkali metal hydroxides, or in dimethylformamide in the presence of alkali metal carbonates. Intermediates VII-IX were prepared from 6-amino-1-alkyl-2,4(1H,3H)-pyrimidinediones I-III via the corresponding 5-bromo derivatives IV-VI and by their aminolysis with the appropriate alkylamines.

A new one-step protocol for the synthesis of acetoxy lactams starting from imides has been developed. This method involves regiospecific reduction of the imide with LiEt 3 BH, then capture of the transient lithium alkoxide by acetic anhydride.

A wide range of pseudorotaxane assemblies containing positively charged pyridinium, pyridinium nicotinamide, imidazolium, benzimidazolium and guanidinium threading components, and macrocyclic isophthalamide polyether ligands have been prepared using a general anion templation procedure. In noncompetitive solvent media, coupling halide anion recognition by a macrocyclic ligand with ion-pairing between the halide anion and a strongly associated cation provides the driving force for interpenetration. Extensive solution 1H NMR binding studies, thermodynamic investigations, and single-crystal X-ray structure determinations reveal that the nature of the halide anion template, strength of the ion-pairing between the anion template and the cationic threading component, and to a lesser extent favorable second sphere pi-pi aromatic stacking interactions between the positively charged threading component and macrocyclic ligand, together with macrocyclic ring size, affect the efficacy of pseudorotaxane formation.

The synthesis and photophysical properties of novel luminescent ruthenium(II) bipyridyl complexes containing one, two, or six lower rim acid-amide-modified calix[4]arene moieties covalently linked to the bipyridine groups are reported which are designed to coordinate and sense luminescent lanthanide ions. All the Ru-calixarene complexes synthesized in this work are able to coordinate Nd(3+), Eu(3+), and Tb(3+) ions with formation of adducts of variable stoichiometry. The absorbance changes allow the evaluation of association constants whose magnitudes depend on the nature of the complexes as well as on the nature of the lanthanide cation. Lanthanide cation complex formation affects the ruthenium luminescence which is strongly quenched by Nd(3+) ion, moderately quenched by the Eu(3+) ion, and poorly or moderately increased by the Tb(3+) ion. In the case of Nd(3+), the excitation spectra show that (i) the quenching of the Ru luminescence occurs via energy transfer and (ii) the electronic energy of the excited calixarene is not transferred to the Ru(bpy)(3) but to the neodymium cation. In the case of Tb(3+), the adduct's formation leads to an increase of the emission intensities and lifetimes. The reason for this behavior was ascribed to the electric field created around the Ru calix[4]arene complexes by the Tb(3+) ions by comparison with the Gd(3+) ion, which behaves identically and can affect ruthenium luminescence only by its charge. However, especially for compounds 1 and 3, it cannot be excluded that some contribution comes from the decrease of vibrational motions (and nonradiative processes) due to the rigidification of the structure upon Tb(3+) complexation. In the case of Eu(3+), compounds 1, 2, and 4 were quenched by the lanthanide addition but the quenching of the ruthenium luminescence is not accompanied by europium-sensitized emission which suggests that an electron-transfer mechanism is responsible for the quenching. On the contrary, compound 3 exhibits enhanced emission upon addition of Eu(3+) (as nitrate salt); it is suggested that the lack of quenching in the [3.2Eu(3+)] adduct is due to kinetic reasons because the electron-transfer quenching process is thermodynamically allowed.

A series of new photo-active rhenium(i) bipyridyl based pseudorotaxane complexes is assembled via halide anion templation.

Surface pre-organisation within robust amidoferrocene self-assembled monolayers can be exploited in the selective electrochemical sensing of anions in both organic and aqueous media.

The synthesis of calix[4]arene based dendrimers containing up to seven calix[4]arene moieties is described, including the X-ray crystal structure of a tris-calix[4]arene branching derivative.

A new synthesis of 2-ethynyl-1,4-dihydropyridine derivatives in two steps from alkyl 3-oxo-5-trimethylsilyl-4-pentynoates via the Hantzsch three-component reaction followed by an alkaline hydrolysis is described.

A novel ruthenium(II) tris(bipyridyl) receptor complex has been prepared and shown by 1H NMR and fluorescence emission spectroscopy to exhibit exclusive selectivity for the dihydrogen phosphate anion in preference to chloride.

Exotic calix[4]arene mono- and di-topic anion receptors containing one and two ruthenium(II) bipyridyl moieties have been prepared and shown by 1H NMR and CV to bind and electrochemically recognise halide, dihydrogen phosphate and hydrogen sulphate anions. The monotopic calix[4]arene anion receptor 8 selectively electrochemically recognises H2PO 4 - in the presence of tenfold excess amounts of HSO 4 - and Cl-.

The synthesis of calix[4]arene based dendrimers containing up to seven calix[4]arene moieties is described, including the X-ray crystal structure of a tris-calix[4]arene branching derivative.