Ligand Chirality Transfer from Solution State to the Crystalline Self-Assemblies in Circularly Polarized Luminescence (CPL) Active Lanthanide Systems.

The synthesis of a family of chiral and enantiomerically pure pyridyl-diamide (pda) ligands that upon complexation with europium [Eu(CFSO)] result in chiral complexes with metal centered luminescence is reported; the sets of enantiomers giving rise to both circular dichroism (CD) and circularly polarized luminescence (CPL) signatures. The solid-state structures of these chiral metallosupramolecular systems are determined using X-ray diffraction showing that the ligand chirality is transferred from solution to the solid state. This optically favorable helical packing arrangement is confirmed by recording the CPL spectra from the crystalline assembly by using steady state and enantioselective differential chiral contrast (EDCC) CPL Laser Scanning Confocal Microscopy (CPL-LSCM) where the two enantiomers can be clearly distinguished.

Fluorescent 4-amino-1,8-naphthalimide Tröger's bases (TBNaps) possessing (orthogonal) 'α-amino acids', esters and di-peptides and their solvent dependent photophysical properties.

The synthesis of fifteen luminescent bis-naphthalimide based Tröger's bases (TBNaps) derived from 4-amino-1,8-naphthalimide (4-Amino-Nap) precursors is described; these scaffolds possess α-amino acids, esters or di-peptides conjugated at the imide site and show minor fluorescence in aqueous solution while being highly emissive in organic solvents. The investigation shows that these TBNaps possessing ICT excited state properties are capable of generating either positive or negative solvatochromic effects in response to changes in polarity and/or the hydrogen bonding capabilities of the medium.

Synthesis and characterisation of biocompatible organic-inorganic core-shell nanocomposite particles based on ureasils.

Organic-inorganic core-shell nanocomposites have attracted increasing attention for applications in imaging, controlled release, biomedical scaffolds and self-healing materials. While tunable properties can readily be achieved through the selection of complementary building blocks, synergistic enhancement requires management of the core-shell interface. In this work, we report a one-pot method to fabricate hybrid core-shell nanocomposite particles (CSNPs) based on ureasils.

The effect of the linker size in C-symmetrical chiral ligands on the self-assembly formation of luminescent triple-stranded di-metallic Eu(iii) helicates in solution.

Chiral lanthanide-based supramolecular structures have gained significant importance in view of their application in imaging, sensing and other functional purposes. We have designed chiral C2-symmetrical ligands (L) based on the use of two 2,6-pyridine-dicarboxylic-amide moieties (pda), that differ from one another by the nature of the diamine spacer groups (from 1,3-phenylenedimethanamine (1(S,S), 2(R,R)) and benzene-1,3-diamine (3(S,S), 4(R,R)) to much bulkier 4,4'-(cyclohexane-1,1-diyl)bis(2,6-dimethylaniline) (5(S,S), 6(R,R))) between these two pda units. The self-assembly between L and Eu(iii) ions were investigated in CH3CN solution at low concentration whereby the changes in the absorbance, fluorescence and Eu(iii)-centred emission spectra allowed us to model the binding equilibria occurring in the solution to the presence of [Eu:L2], [Eu2:L2], [Eu2:L3] assemblies and reveal their high binding constant values.

Surface-Modified Gold Nanoparticles Possessing Two-Channel Responsive Eu /Tb Cyclen Complexes as Luminescent Logic Gate Mimics.

The development of material-supported molecular logic gate mimics (MGLMs) for contained application and device fabrication has become of increasing interest. Herein, we present the formation of ≈5 nm gold nanoparticles (AuNPs) that have been surface-modified (via a thiol linkage) with heptadentate cyclen-based complexes of europium and terbium for sensing applications using delayed lanthanide luminescence and as integrated logic gate mimics within competitive media.

White-light emission from discrete heterometallic lanthanide-directed self-assembled complexes in solution.

White-light-emitting materials have attracted significant interest in recent years due to their potential applications in solid-state lighting and flat-panel displays. Design of such materials is challenging and often relies on the use of multiple fluorophores despite the fact that single component systems yield materials with enhanced stability and reproducibility. Herein, we have developed a white-light-emitting system based on the formation of discrete lanthanide-based self-assembled complexes using a newly-designed ligand.

Cyclen lanthanide-based micellar structures for application as luminescent [Eu(iii)] and magnetic [Gd(iii)] resonance imaging (MRI) contrast agents.

The synthesis of coordinatively unsaturated tetra-substituted 1,4,7,10-tetraazacyclododecane (cyclen) lanthanide complexes is described; these structures, possessing hydrophobic (C12-alkyl) tails and hydrophilic head groups, self-assemble into supramolecular micellar structures in aqueous solution, and hence can be utilised as novel contrast agents for MRI.

Towards multifunctional lanthanide-based metal-organic frameworks.

We report the synthesis, structure and physicochemical attributes of a new holmium(III)-based metal-organic framework whose 3D network structure gives rise to porosity; the reported structure-type can be varied using a range of different lanthanide ions to tune the photophysical properties and produce ligand-sensitised near-infrared (NIR) and visible light emitters.

Lanthanide-functionalized nanoparticles as MRI and luminescent probes for sensing and/or imaging applications.

The combination of lanthanides and nanoparticles to develop new hybrid nanomaterials has become a highly topical area of research in the field of sensing, biomedical imaging, drug delivery, etc. However, these novel nanomaterials have to be carefully designed to ensure that the unique properties conveyed by each component, i.e.

Thiourea derived Tröger's bases as molecular cleft receptors and colorimetric sensors for anions.

Thiourea-functionalized Tröger's base receptors 1 and 2 have been synthesized and evaluated as novel for the recognition of anions. Receptor 2 gave rise to significant changes in the absorption spectrum upon titration with AcO(-) and H2PO4(-) and acted as a colorimetric sensor for F(-), the interaction of which was also evaluated using (1)H NMR spectroscopy.

Efficient quenching of TGA-capped CdTe quantum dot emission by a surface-coordinated europium(III) cyclen complex.

Extremely efficient quenching of the excited state of aqueous CdTe quantum dots (QDs) by photoinduced electron transfer to a europium cyclen complex is facilitated by surface coordination to the thioglycolic acid capping ligand. The quenching dynamics are elucidated using steady-state emission and picosecond transient absorption.

New trick for an old ligand! The sensing of Zn(II) using a lanthanide based ternary Yb(III)-cyclen-8-hydroxyquinoline system as a dual emissive probe for displacement assay.

A novel near-infrared (NIR) emissive lanthanide-based zinc sensor was designed, based on the self-assembly in aqueous solution between the nonemissive coordinatively unsaturated Yb(III) cyclen complex 2·Yb and the sulfonated 8-hydroxyquinoline (8-HQS) chromophore, which was employed as a sensitizing antenna. The resulting ternary complex, 2·Yb·8-HQS, displayed metal-centered emission in the NIR range upon excitation of the antenna with high quantum yield of Q = 0.23 ± 0.

Luminescent lanthanide-functionalized gold nanoparticles: exploiting the interaction with bovine serum albumin for potential sensing applications.

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.

Sensing of biologically relevant d-metal ions using a Eu(III)-cyclen based luminescent displacement assay in aqueous pH 7.4 buffered solution.

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.

Luminescent lanthanide helicates self-assembled from ditopic ligands bearing phosphonic acid or phosphoester units.

A series of hexadentate ditopic receptors incorporating benzimidazole moieties have been designed, which are fitted with phosphonic acid or phosphoethylester coordinating units. In addition, poly(oxyethylene) pendants have been introduced on the benzimidazole backbone of two ligands to increase water solubility. The ligands self-assemble with lanthanide ions under stoichiometric conditions, yielding triple-stranded homobimetallic helicates, as ascertained by mass spectrometry and UV-visible titrations.

Lanthanide bimetallic helicates for in vitro imaging and sensing.

As the need for targeting luminescent biolabels increases, for mapping selected analytes, imaging of cells and organs, and tracking in cellulo processes, lanthanide bimetallic helicates are emerging as versatile bioprobes. The wrapping of three ligand strands around two metallic centers by self-assembly affords robust molecular edifices with tunable chemical and photophysical properties. In addition, heterometallic helical chelates can be assembled leading to bioprobes with inherent chiral properties.

A versatile ditopic ligand system for sensitizing the luminescence of bimetallic lanthanide bio-imaging probes.

The homoditopic ligand 6,6'-[methylenebis(1-methyl-1H-benzimidazole-5,2-diyl)]bis(4-{2-[2-(2-methoxyethoxy)ethoxy]ethoxy}pyridine-2-carboxylic acid) (H(2)L(C2)) has been tailored to self-assemble with lanthanide ions (Ln(III)), which results in the formation of neutral bimetallic helicates with the overall composition [Ln(2)(L(C2))(3)] and also provides a versatile platform for further derivatization. The grafting of poly(oxyethylene) groups onto the pyridine units ensures water solubility, while maintaining sizeable thermodynamic stability and adequate antenna effects for the excitation of both visible- and NIR-emitting Ln(III) ions. The conditional stability constants (log beta(23)) are close to 25 at physiological pH and under stoichiometric conditions.

A polyoxyethylene-substituted bimetallic europium helicate for luminescent staining of living cells.

The homoditopic ligand H2LC3 has been designed to form neutral triple-stranded bimetallic helicates of overall composition [Ln2(LC3)3]. The grafting of the polyoxyethylene fragments ensures water solubility and also favors cell penetration while being amenable to further derivatization. The ligand pKa values have been determined by spectrophotometric titration and range from 3.

Luminescent lanthanide bimetallic triple-stranded helicates as potential cellular imaging probes.

Water-soluble triple-stranded [Ln(2)(L)(3)] helicates have been successfully tested as imaging probes in human cervical adenocarcinoma cells (HeLa), the complex being not toxic and clearly staining their cytoplasm in a concentration-dependent manner.

A novel strategy for the design of 8-hydroxyquinolinate-based lanthanide bioprobes that emit in the near infrared range.

A new polydentate tripodal ligand T2soxMe was synthesized to take advantage of the chelating effect of tridentate 8-hydroxyquinolinate subunits. Potentiometric and spectrophotometric titrations reveal seven pK(a) values of between 3.7 and 10.

Dual emission from luminescent nonalanthanide clusters.

Clusters containing nine lanthanide and six sodium ions are crystallized with the help of a tridentate ligand bearing a phosphonic acid group; the structure of the Eu(III) compound reveals a host-guest assembly Eu [symbol: see text] Na6Eu8L16 with a substantial quantum yield (32%). A similar Eu(III)-Yb(III) structure displays dual luminescence in the visible (Eu(III)) and NIR (Yb(III)) ranges.

Stable 8-hydroxyquinolinate-based podates as efficient sensitizers of lanthanide near-infrared luminescence.

New polydentate ligands (e.g., Tsox and TsoxMe) have been synthesized to take advantage of the chelating effect of bidentate 8-hydroxyquinolinate subunits connected to a N,N,N',N'-tetraaminopropyl-1,2-ethylenediamine framework and with the aim of sensitizing the NIR luminescence of Nd(III) and Yb(III) ions.

Lanthanide 8-hydroxyquinoline-based podates with efficient emission in the NIR range.

The novel hydroxyquinoline-containing tetrapodal ligand forms water soluble and stable chelates and is a good sensitizer of the NIR luminescence of its Nd(III) and Yb(III) complexes; its easy synthesis opens the way for potential biomedical applications.

Influence of anionic functions on the coordination and photophysical properties of lanthanide(III) complexes with tridentate bipyridines.

A series of four ligands based on a 5'-methyl-2,2'-bipyridyl framework substituted in the 6 position by a carboxylic acid, a phosphonic acid, a monoethyl ester phosphonic acid, or a diethyl ester phosphonic acid are described. The pK(a) values of all ligands and their assignments are determined by a combination of UV-vis absorption spectroscopy and (1)H and (31)P NMR spectroscopy. The ability of the tridentate ligands to form complexes with trivalent lanthanide cations (Ln = La, Nd, Eu, and Lu) in buffered water solutions (Tris-HCl, pH = 7.