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The synthesis and photophysical properties of 1 and 2, two Ru(II)-polypyridyl based-1,8-naphthalimide Tröger's bases, are described; these were found to stabilize double stranded DNA, undergo rapid cellular uptake, displaying good luminescence without affecting cell viability even after 24 hours of incubation., (This journal is © The Royal Society of Chemistry 2012)

The design and synthesis of dinuclear-lanthanide complexes possessing triazole-based bridges, formed by using copper catalysed 1,3-cycloaddition reactions between heptadentate alkyne functionalised cyclen europium or terbium complexes and di-azides (CuAAC reactions), are described. While this click reaction worked well for the formation of the homo-Eu(III) and Tb(III) bis-tri-arm cyclen N,N-dimethyl acetamide complexes, 2Eu and 2Tb, and for the homo-Eu(III) chiral N-methylnaphthalene based complexes 3Eu (S,S,S) and 4Eu (R,R,R), the formation of the Eu(III) complex of the primary amide analogue of 2, namely 1Eu, was not successful, clearly demonstrating the effect that the nature of the pendant arms has on this reaction. Furthermore, the click reactions between the free alkyne cyclen bis-derivatives (5-8) and the di-azide were unsuccessful, most likely due to the high affinity of the cyclen macrocycles for Cu(II). The Eu(III) complexes of 2-4 and 2Tb all gave rise to sensitised metal ion centred emission upon excitation of the triazole or the naphthalene antennae in methanol solution, and their hydration states were determined, which showed that while the Eu(III) mono-nuclear complexes had q ∼ 2, the click products all had q ∼ 1. In the case of 3Eu (S,S,S) and 4Eu (R,R,R), the circular polarised emission (CPL) was also observed for both, demonstrating the chiral environment of the lanthanide centres.

The investigation into the luminescence properties of a lanthanide-binding peptide, derived from the Ca-binding loop of the parvalbumin, and modified by incorporating a 1,8-naphthalimide (Naph) chromophore at the N-terminus is described. Here, the Naph is used as a sensitising antenna, which can be excited at lower energy than classical aromatic amino acids, such as tryptophan (the dodecapeptide of which was also synthesised and studied herein). The syntheses of the Naph antenna, its solid phase incorporation into the dodecapeptide, and the NMR investigation into the formation of the corresponding lanthanide complexes in solution is presented. We also show that this Naph antenna can be successfully employed to sensitize the excited states of both europium and terbium ions, the results of which was used to determined the stability constants of their formation complexes, and we demonstrated that our peptide 'loop' can selectively bind these lanthanide ions over Ca(II).

The reaction between the asymmetrical pyridyl ligands 3 (R) and 4 (S) and Eu(III) in CH(3)CN give rise to the formation of lanthanide luminescent 'half-helicates' in 1 : 3 (Ln:ligand) stoichiometry; the formation of which was observed by monitoring the changes in the ground and the excited state properties of the ligands, and in the time-resolved Eu-centred and the CPL emission.

The synthesis and binding investigations of first generation C(3v)-symmetrical hydrogen bonding urea-amide based tripodal receptors, 1-6, with various anions such as acetate, phosphate, sulfate and chloride in DMSO-d(6) are presented. Analysis of the (1)H NMR titrations of 1-6 showed on all occasions the selective formation of 1 : 1 stoichiometries.

The synthesis and photophysical and biological investigation of Ru(II)-polypyridyl stabilized water-soluble, luminescent gold nanoparticles (AuNPs) are described. These structures bind to DNA and undergo rapid cellular uptake, being localized within the cell cytoplasm and nucleus within 4 h.

As luminescent surface-functionalized gold nanoparticles emerged as potential powerful analytical tools in the biomedical fields, understanding the interaction of such systems with proteins has become crucial. In the present study, the interaction of luminescent water-soluble gold nanoparticles (AuNP-1·Eu-nta), obtained through the self-assembly of a naphthalene β-diketone antenna with a Eu(III) cyclen complex tethered to the gold surface via a C(12) alkyl thiol spacer, with bovine serum albumin (BSA) was investigated. The changes in the UV-visible absorption and fluorescence spectra of both the antenna and protein, as well as in the time-resolved Eu(III)-centered emission, of the resulting self-assembly were monitored, at physiological pH, as a function of the BSA concentration. We demonstrate that the Eu(III) emission arising from the self-assembly on the AuNP surface is almost completely quenched upon addition of BSA. Binding constant determination clearly showed that the sensitizing antenna was not displaced and that the quenching was the result of the interaction between the antenna and BSA. Detailed spectroscopic studies performed on the nta-BSA system brought a better insight in the strength of such interaction as well as its effect on the protein secondary structure. Finally, the information gathered on each system resulted in applying AuNP-1·Eu-nta-BSA for the luminescent detection of drugs via the perturbation of the nta-BSA interaction. Competitive titrations using ibuprofen and warfarin showed that nta was located in the binding site II of BSA and that the presence of warfarin, a site I drug, did not interfere with the detection of site II ibuprofen., (© 2011 American Chemical Society)

The formation of self-assembly complexes between the ligands 1 (SS) and 2 (RR) and terbium or europium was undertaken and shown (using various spectroscopic titrations) to give rise to the exclusive formation of 2:1 (L:Ln) stoichiometry and not the anticipated 3:1 stoichiometry., (This journal is © The Royal Society of Chemistry 2011)

1·Eu·BPS was developed as a luminescent lanthanide sensor for use in displacement assays for detection of d-metal ions by monitoring the changes in the europium emission, which was quenched for iron(II), with a detection limit of ∼10 pM (0.002 μg L(-1)) for Fe(II) in buffered pH 7.4 solution., (This journal is © The Royal Society of Chemistry 2011)

The reaction of tetrasodium-4,4',6,6'-tetracarboxy-2,2'-bipyridine (Na(4)L) with various lanthanide ions yields a family of isostructural supramolecular {Na(2)[Ln(2)L(2)]} complexes (1-4), where Ln(III) = Eu, Nd, Gd, and Tb. Strikingly, these complexes luminesce in buffered H(2)O or D(2)O solutions in either the visible or near-IR regions, despite their high hydration states.

The quaternarized pdppz derivative 1 was shown to bind strongly to DNA with concomitant changes in its ground and excited state photophysical properties. Furthermore, the compound also showed rapid cellular uptake, and induced apoptosis upon light irradiation in various cancer cell lines after 24 hours of incubation.

This critical review focuses on the development of anion sensors, being either fluorescent and/or colorimetric, based on the use of the 1,8-naphthalimide structure; a highly versatile building unit that absorbs and emits at long wavelengths. The review commences with a short description of the most commonly used design principles employed in chemosensors, followed by a discussion on the photophysical properties of the 4-amino-1,8-naphthalimide structure which has been most commonly employed in both cation and anion sensing to date. This is followed by a review of the current state of the art in naphthalimide-based anion sensing, where systems using ureas, thioureas and amides as hydrogen-bonding receptors, as well as charged receptors have been used for anion sensing in both organic and aqueous solutions, or within various polymeric networks, such as hydrogels. The review concludes with some current and future perspectives including the use of the naphthalimides for sensing small biomolecules, such as amino acids, as well as probes for incorporation and binding to proteins; and for the recognition/sensing of polyanions such as DNA, and their potential use as novel therapeutic and diagnostic agents (95 references).

The cyclen-based ligand 1, possessing a [1,10]-phenanthroline moiety as a pendant arm, has been used as a ditopic ligand for the complexation of d- and near infrared (NIR) emitting (and) f-metal ions. This ligand forms kinetically stable complexes, 1·Ln, with lanthanide ions such as Ln = ytterbium, neodymium, and lutetium (formed as a non-IR emitting reference compound), the synthesis and photophysical properties of which are described herein in detail. These 1·Ln complexes were then used as building blocks for the formation of mixed d−f heteropolymetallic self-assemblies, where the phen moiety was used to complex a ruthenium (Ru(II)) ion, giving the d−f3 complexes Ru·Ln3 (Ln = Nd(III), Yb(III), Lu(III)). The formation of these supramolecular coordination conjugates was studied by using absorption and luminescence spectroscopy, while the solution structure of the Ru·Lu3 was elucidated by 1H NMR in D2O and H2O. Of these conjugates, both Ru·Nd3 and Ru·Yb3 displayed an intense NIR-emission in H2O at pH 7.4 (with Q(Yb)(L) = 0.073% and Q(Nd)(L) = 0.040%) and in D2O (with QYbL = 0.23% and Q(Nd)(L) = 0.10%). By comparison with their monometallic analogues Ln·1 (Ln = Nd(III), Yb(III)), we demonstrate that our new design possesses an enhanced sensitization efficiency for lanthanide metal centered sensitization upon using the [Ru(phen)3] moiety (d → f energy transfer) as a visibly exciting antenna, and we demonstrate that the intensity of the Ru(II)-based luminescence strictly correlates to the efficiency of the d → f energy transfer processes.

The synthesis and characterization of three bis-1,8-naphthalimide-containing Tröger's bases 1-3, formed from the corresponding 4-amino-1,8-naphthalimide precursors 7-9 in a single step, is described. The photophysical investigation of 1-3 and 7-9 was carried out in various organic solvents as well as in water and as a function of pH using UV/vis and fluorescence spectroscopy. As for their 4-amino-1,8-naphthalimide precursors 7-9, both the ground-state and excited-state characteristics of 1-3 were dependent on the polarity and the hydrogen-bonding ability of the solvent medium. The DNA-binding affinities of 1-3 were also studied in aqueous solution at pH 7.4, in the presence of calf-thymus DNA (ct-DNA), using various UV/vis absorption and fluorescence spectroscopic methods. These molecules exhibited significant DNA-binding ability, where large binding values K(b) in the range of 10(6) M(-1) were determined. Such strong binding to ct-DNA was maintained even in competitive media (50 and 160 mM NaCl) and was also found to be irreversible regardless of the concentration of the ionic strength. Thermal denaturation experiments also demonstrated that the interaction of 1-3 with ct-DNA gave rise to significant stabilization in the double-helical structure of DNA. The binding affinity of 1-3 for ct-DNA was also compared to that of their 4-amino-1,8-naphthalimide precursors 7-9, determined by fitting of data using "intrinsic" methods and ethidium bromide displacement assays. The latter method gives outstanding binding constants for 1-3 in the range of 10(7) M(-1).

A series of substituted 1,4,7,10-tetraazacylcododecane ligands 1-4, possessing sensitizing nitrobenzene or naphthalene antennae, as one of the amide pendant arms, and their complexes with europium(III) were synthesised. The protonation constants and the metal ion stability constants of two of these ligands were determined by potentiometric titration. The pK(a) of the water molecules coordinated to the complexed metal ion were determined by both luminescent and potentiometric measurements. The luminescence pH dependence of a further three Eu(III) complexes, 5-7, which lack any antennae, were also studied with the aim of gaining a better understanding of the role of the metal bound water molecules in the luminescence properties of such complexes upon direct excitation of the lanthanide ion. The results from these luminescent measurements demonstrate that the Eu(III) emission was significantly modulated as a function of pH for all the complexes, which we assigned to changes occurring in the coordination environment of the ion within the cyclen system, caused by deprotonation of metal bound water molecules and/or deprotonation of pendent amide arms.

Photoliberation of a caged, chelating naphthalene antenna greatly enhances the luminescence of a Eu(III)-cyclen complex due to metal-bound water displacement and sensitization by the antenna, giving a lanthanide-labelling strategy in different media, being optimal in the presence of a TMADS surfactant.

The synthesis and photophysical evaluation of a new supramolecular lanthanide complex is described which was developed as a luminescent contrast agent for bone structure analysis. We show that the Eu(III) emission of this complex is not pH dependent within the physiological pH range and its steady state emission is not significantly modulated by a series of group I and II as well as D-metal ions and that this agent can be successfully employed to image mechanically formed cracks (scratches) in bone samples after 4 or 24 h, using confocal laser-scanning microscopy.

The synthesis and photophysical and biological investigation of fluorescent 1,8-naphthalimide conjugated Troger's bases 1-3 are described. These structures bind strongly to DNA in competitive media at pH 7.4, with concomitant modulation in their fluorescence emission. These structures also undergo rapid cellular uptake, being localized within the nucleus within a few hours, and are cytotoxic against HL60 and (chronic myeloid leukemia) K562 cell lines.

The thiourea based 4-amino-1,8-naphthalimide molecules 1-5 were designed as fluorescent anion sensors and their photophysical properties investigated upon recognition of biologically relevant anions such as acetate, dihydrogen phosphate and fluoride in DMSO. Synthesised in a single step from their respective aniline precursors, 6-9, these molecules were designed on the fluorophore-spacer-receptor principle, where in the case of sensors 1-3 the thiourea anion recognition moieties were connected to the fluorophore via the 4-amino moiety, while sensors 4 and 5 had the thiourea moieties connected to the 'imide' via a CH2 spacer. The current study showed that 1-5 operated as photoinduced electron transfer (PET) sensors, as no significant changes were observed in their absorption spectra, while their fluorescence emissions were quenched upon recognition of ions such as AcO(-), H2PO4(-) and F(-), which demonstrates that bidirectional PET sensing occurs in such naphthalimide based anion sensors.

The formation of a self-assembly between a sensitising antenna and an Eu(III) functionalised cyclen complex 1.Eu, tethered to a gold surface via a C(12) alkyl thiol spacer, is described where changes in the Eu(III) emission signal the formation, and dissociation, of a ternary complex.

The synthesis and photophysical evaluation of two enatiomerially pure dimetallic lanthanide luminescent triple-stranded helicates is described. The two systems, formed from the chiral (R,R) ligand 1 and (S,S) ligand 2, were produced as single species in solution, where the excitation of either the naphthalene antennae or the pyridiyl units gave rise to Eu(III) emission in a variety of solvents. Excitation of the antennae also gave rise to circularly polarized Eu(III) luminescence emissions for Eu(2):1(3) and Eu(2):2(3) that were of equal intensity and opposite sign, confirming their enantiomeric nature in solution providing a basis upon which we were able to assign the absolute configurations of Eu(2):1(3) and Eu(2):2(3).

The synthesis and photophysical properties of the Eu(iii) complex , based on the use of 1,10-phenanthroline (phen) as a combined sensitizing antenna and a transition metal ion coordinating ligand, is described. The long-wavelength Eu(iii) emission from this complex was found to be highly pH sensitive, giving rise to a 'off-on-off' pH profile with maximum emission occurring within the physiological pH range. This allowed for the use of as a luminescent sensor for transition metal ions, where the titration with ions such as Cu(ii), Co(ii) and Fe(ii) gave rise to the formation of mixed f-d nuclear complexes, with concomitant changes in the photophysical properties of . Here, changes in both the ground and the singlet excited state properties of the phen antenna were observed, but the largest changes were observed for the delayed Eu emission, which was fully quenched upon titration with these ions in aqueous pH 7.4 buffered solutions. In comparison, no changes were observed in the Eu(iii) emission upon titration with ions such as Zn(ii) or group I and II ions. From these changes, we were able to demonstrate the binding stoichiometry and the binding constant for the formation of novel supramolecular complexes between and Cu(ii), Co(ii) and Fe(ii), which showed that either two or three equivalents of complexed to each of these transition metal ions, giving rise to the formation either linear f-d-f or branched f(3)-d based mixed nuclear complexes in solution.

A cyclen based lanthanide luminescent sensor, , has been developed by taking advantage of a combination of hydrogen bonding and f-metal ion coordination binding sites for anionic species. Analysis of the ground state, the emission from the singlet and the Tb(iii) excited states clearly show the ability of the Tb(iii) complex to signal the presence of anions in CH(3)CN, through multiple binding interactions consisting of hydrogen bonding and metal coordination. The delayed lanthanide luminescence from the Tb(iii) diaryl-urea complex was found to be significantly enhanced only upon recognition of H(2)PO(4)(-), at the same time as displaying good selectivity over other competitive anions, such as CH(3)COO(-).

A new family of mixed-lanthanide (Yb(III) and Nd(III)) transition-metal (f-d) cyclen-Ru(II)(phen)(3) (phen = 1,10-phenanthroline) complexes were synthesized as dual visible- and near-infrared (NIR)-emitting DNA probes/sensors. Significant changes were seen in both the Ru(II) visible and the Yb(III)-centered NIR emission, which was switched off upon binding to DNA at pH 7.4. In contrast, no changes were seen in the Nd(III) emission of the analogue f-d conjugate.

The design, synthesis, and X-ray crystallographic analysis of three simple diaryl-urea based anion receptors possessing an amide moiety on one of the aryl groups, and an electron withdrawing CF(3) group on the other, is described. The three receptors differ only in the position of the amide functionality relative to the hydrogen bonding urea moiety (being para, meta, and ortho for 1, 2, and 3, respectively). This simple modification was shown to have a significant effect on the anion recognition ability, the strength of the recognition process, and the stoichiometry (host/guest) for these sensors. We demonstrate, by using both UV-vis absorption and (1)H NMR spectroscopy, that these factors are caused by the ability of the amide moiety to both modulate the anion binding selectivity and the sensitivity of the urea moiety. We also demonstrate that, in the case of 1 and 2, this anion recognition at the urea moiety leads to concomitant activation (through enhanced inductive effect) in the amide functionality toward anions, which leads to the formation of an overall 1:2 (sensor/anion) binding stoichiometry for these receptors. This "activation" we describe as being an example of a "positive allosteric activation" by the urea site, caused directly by the first anion binding interaction, which to the best of our knowledge, has not been previously demonstrated for anion recognition and sensing.

The design, synthesis and physical evaluation of 1, a visible colorimetric 'naked eye' pyridyl based bis-amidothiourea sensor for anions, is described. This charge neutral sensor gives rise to significant changes in the absorption spectra upon interactions with several important biological anions such as AMP and ADP in 4:1 DMSO-H(2)O solution, while ATP was not detected. These colorimetric changes are due to the formation, or the combination of hydrogen bonding complexes and/or deprotonation between these anions and 1.

The synthesis and photophysical evaluations of two new fluorescent photoinduced electron-transfer (PET) anion sensors, 1 and 2, is described. These are based on 4-amino-1,8-naphthalimide fluorophores and diarylthiourea anion receptors, connected via a methylene spacer to the imide. The sensing of acetate, phosphate, and fluoride, on all occasions, gave rise to quenching in the fluorescence of 1 and 2, similar to that seen for the structural isomer 3. These results demonstrate that bidirectional PET sensing occurs in such naphthalimide-based anion sensors.

The synthesis, NMR and luminescent analysis of a novel polypeptide possessing a sensitising naphthalimide antenna at the amino terminus, and a model compound with a Trp moiety, and their Eu(iii) and Tb(iii) complexes are described.

Luminescent europium and terbium complexes and a mixed Eu(III)-Tb(III) complex were prepared, each with three macrocycles coordinating to a single lanthanide ion to form a trimetallic system, and can be used for the ratiometric sensing of anions in the case of the mixed complex.

1.Eu, a cyclen based Eu(III)-thiol conjugate, was incorporated onto the surface of water-soluble gold nanoparticles to give AuNP-1.Eu. The self-assembly between AuNP-1.Eu and the antenna 2 resulted in the formation of the highly luminescent lanthanide system, AuNP-1.Eu-2, at pH 7.4. The sensing of flavin monophosphate 3 is demonstrated, whereby 3 displaced the antenna 2 in AuNP-1.Eu-2, resulting in the formation of AuNP-1.Eu-3 and quenching of the Eu(III) emission.

The synthesis of the two novel 1,8-naphthalimideruthenium conjugates Ru-Nap-NO(2) and Ru-Nap-NH(2) and their photophysical evaluation upon interaction with DNA is reported. Significant changes were seen in both the absorption and emission spectra upon interaction of both conjugates with DNA, from which large binding constants were determined. Moreover, highly efficient DNA cleavage was observed upon irradiation for 5 min, during which supercoiled DNA was converted to nicked and linear DNA by Ru-Nap-NH(2).

The synthesis and the spectroscopic studies of the amidourea based calix[4]arene sensors 1 and 2 are described. The 4-nitrophenyl based sensor 1 was synthesized in two steps from the corresponding calix [4]arene tetraethyl ester and shown to give rise to color changes in the UV-vis spectra in DMSO upon recognition of pyrophosphate and fluoride. Fitting the changes in the absorption spectra using nonlinear regression analysis indicated strong binding of several anions by 1 such as acetate and hydrogen phosphate in 1:1 (Host:Guest) stoichiometry, and at higher concentration in 1:2 stoichiometry. The preorganized calix-cavity was, however, not found to host chlorine while binding of bromide was determined. At high concentrations of these anions, significant colorimetric changes were also observed that were clearly visible to the naked eye for both pyrophosphate and fluoride. The phenyl analogue 2 was made to enable analysis of the anion recognition using 1H NMR titrations and showed that ions such as phosphate were bound in 1:1 stoichiometry, whereas the "urea" protons were shown to be significantly affected upon coordination to the anion.

The delayed lanthanide luminescence of the terbium [Tb(III)] diaryl-urea complex 1xTb is significantly enhanced upon sensing of dihydrogenphosphate (H2PO4(-)) in CH3CN, which occurs through multiple anion binding through hydrogen bonding interactions and potential metal ion coordination to Tb(III).

This article gives some highlights of the recent advances in the development of novel lanthanide based complexes, conjugates and self-assembly structures formed from the use of organic ligands and organo-metallic (transition metal) complexes, that are designed with the aim of capitalising on the high coordination requirement of the lanthanide ions. The examples shown, demonstrate the versatility of the lanthanide ions as luminescent probes and sensors that emit at long wavelength either in the visible or the near infrared (NIR) part of the electromagnetic spectrum.

Three conformationally preorganised host molecules based on the [3]polynorbornyl framework and incorporating di-urea receptors were synthesised and their interaction with a series of anions investigated by (1)H NMR spectroscopy. A high affinity of each host molecule for dihydrogenphosphate (H(2)PO(4)(-)) and dihydrogenpyrophosphate (H(2)P(2)O(7)(2-)) was identified. In addition to binding to the urea receptors of the host molecules, evidence for an interaction involving the non-polar C-H groups within the binding cavity of the framework and guest anions was also discovered. Furthermore, an unusual 2 : 1 host-to-anion stoichiometry was indicated when binding H(2)P(2)O(7)(2-), and a model for the anion-mediated self-assembly of this complex species is proposed.

The design, synthesis, and characterization of a novel dinuclear Eu(III) bismacrocyclic conjugate 1.Eu2 as a delayed luminescent lanthanide sensor for dicarboxylates is discussed. The sensor was shown to bind small dicarboxylic acids such as aspartic, malonic, succinic, or glutaric acid in pH 6.5 solutions. However, only malonic acid gave rise to selective Eu(III) luminescent enhancements, as the emission was reduced for all of the other acids.

The design and synthesis of two novel fluorescent sensors based on the photoinduced electron transfer (PET) concept, and , for the detection of zinc under competitive media is described. These sensors are based on the 4-amino-1,8-naphthalimide fluorophore, which has an absorption band centred at 450 nm and emits in the green with lambda(max) approximately 550 nm. By functionalizing the chromophore with a simple benzyl or ethyl-aryl based iminodiacetate receptor at the 4-position, both high selectivity and sensitivity were achieved for the sensing of Zn(II) over other competitive transition and Group I and II metal ions. These sensors were also shown to be pH independent, with a pKa of 2.3 being determined for , which allows these to be used in highly competitive pH media. Upon sensing of Zn(II) the fluorescence emission spectrum is 'switched on' demonstrating the suppression of PET from the receptor to the fluorophore. For , the sensing of Zn(II) was achieved with Kd = 4 nM when measured in pH 7.4 buffered solution, in the presence of 1.1 mM of EGTA.

The synthesis and the photophysical evaluation of a novel pH dependent lanthanide luminescent self-assembly in water between a cyclen based europium complex and a beta-diketonate is described and its use as a luminescent sensor in displacement assays for anions such as acetate, bicarbonate and lactate, where the Eu(III) emission was quenched upon anion recognition.

The development of novel mixed lanthanide-transition-metal (f-d) based supramolecular self-assemblies made from neodymium- and ytterbium-based tetraamide-functionalized cyclen complexes bearing a single 1,10-phenanthroline moiety coordinating to a RuII(bipy)2 (bipy = bipyridine) unit is described. Excitation of the Ru(II) metal-to-ligand charge-transfer band in water gave rise to long-wavelength sensitized emission from the Yb(III) or Nd(III) centers, observed in the near-infrared.

The synthesis and photophysical properties of a coordinatively unsaturated cationic dinuclear terbium complex, 2.Tb(2), that can detect the presence of mono- or bis(carboxylates) in buffered aqueous solution at physiological pH is described. Full ligand synthesis and structural characterization of 2.Na(2) are also described. Spectroscopic measurements determined that each Tb(III) metal center has two metal-bound water molecules (q = 2). The recognition or sensing of N,N-dimethylaminocarboxylic acid, 4, and the bis(carboxylate) terephthalic acid, 5, which can also function as sensitizing antennae, was found to occur through the binding of these carboxylates to the metal center via the displacement of the metal bound water molecules. This gave rise to the formation of luminescent ternary complexes in solution in 2:1 or 1:1 (ion:2.Tb(2)) stoichiometry, respectively. Aliphatic bis(carboxylates) also bind to 2.Tb(2) where the selectivity for the ion recognition and stoichiometry was dictated by the structure of the anion, being most selective for pimelic acid, 6. Binding of either l- or d-tartaric acid gave rise to the formation ternary complex formation, with 2:1 stoichiometry, where the ion recognition resulted in quenching of the lanthanide emission.

The design and synthesis of several novel X-ray contrast agents 1-3, developed for targeting bone structures, and in particularly microcracks in bones, using CT (Computer Tomography) detection is described. These contrast agents are based on the use of the well known triiodobenzene platform, which was conjugated into one or more phenyliminodiacetate moieties, which can be used to 'lock' onto bone matrices. Compounds 1-3 were all tested for their ability to visualise cracks in bone structures (bovine bones) using micro-CT imaging.

The synthesis of several cyclen based lanthanide [Eu(III) and La(III)] complexes is described; these metallo ribonuclease mimics are based on the use of alkyl amines as pendent arms, which give rise to fast hydrolysis within the physiological pH range of HPNP (an RNA model compound) that is highly dependent on the length of the alkyl spacer.

[reaction: see text] The synthesis of the novel Eu(III) cyclen complex, Eu1, is described. In buffered pH 7.4 water, the Eu(III) emission was "switched on" upon excitation of the Terpy antenna. In the presence of various transition-metal ions (e.g., Fe(II) and Ni(II)), both the singlet-excited state and the Eu(III) emission were quenched ("switched off"), whereas in the ground state, an MLCT band was formed, signifying the formation of stable mixed linear trimetallic f-d supramolecular self-assemblies.

The design and synthesis of several bis-macrocyclic cyclen (1,4,7,10-tetraazacyclododecane) ligands and their corresponding lanthanum or europium complexes is described; these dinuclear lanthanide systems were made by connecting two macrocyclic cyclen moieties through a rigid, covalent, p-xylylenediamide bridge or a flexible aliphatic hexane bridge. These ligands were subsequently functionalised with six acetamide pendant arms (CONR1R2: R1 = R2 = H or CH3, or R1 = H, R2 = CH3). The corresponding lanthanide bis-complexes were then formed by reaction with La(III) and Eu(III) triflates, yielding overall cationic (+VI charged) complexes.

Microdamage accumulation leads to reduced bone strength and fracture. Intact, damaged and Rose Bengal stained cortical bone specimens were studied using SEM and EDXA imaging. SEM coupled with EDXA studies showed selective labelling of surface damage due to binding of dye at free lattice sites. A series of novel iodinated X-ray contrast agent were synthesised. These agents demonstrated excellent stability, water solubility and lack of atropisomerism. Preliminary imaging studies, using cone-beam mu-CT, demonstrated their ability to provide visible contrast in the solid state on bone surfaces.

[structure: see text] The synthesis and UV-vis and NMR spectroscopic studies of thiourea-based colorimetric sensors for anions are presented. These sensors can recognize anions through hydrogen binding even in competitive pH-buffered aqueous solutions, giving rise to large color changes that are clearly visible to the naked eye.