Supramolecular "soft" assemblies based on copper (I) coordination complexes

Copper(I) coordination complexes with N^N chelating oligopyridines are valuable candidates for applications in solar energy conversion1 or lightning technologies2 because of their excellent photophysical and photochemical properties and for the low cost and ready availability of the metal. The most attractive systems are based on ligands able to stabilise their tetrahedral geometry (D2d symmetry) and to hinder the flattening distortions which facilitates oxidation to Cu(II) species.3 Herein we present the synthesis and characterisation of new stable Cu(I) complexes based on functionalised 2,2’-biquinoline ligands (Figure 1) that self-assemble into “soft” supramolecular architectures. The stoichiometry and purity of all compounds were determined using elemental analyses, Atomic Absorption, IR and 1H NMR spectroscopies. The functionalisation of the biquinoline ligand with long alkyl chains yielded thermotropic liquid crystalline systems (CuL1_X and CuL2_X), whereas insertion of hydrophilic groups promoted the assembly in water into supramolecular aggregates (CuL3_X). The thermal behaviour of complexes CuLn_X with n = 1 and 2 was investigated by polarized optical microscopy (POM) and differential scanning calorimetry (DSC). UV-Vis studies on CuL3_X evidenced the presence of supramolecular aggregates in water. Stabilization of Cu(I) systems can be also achieved by building supramolecular assemblies and thus blocking the fluxional process towards a distorted “Cu(II)-like” geometry in concentrated solution of complexes

"Smart" molecular engineering of metallomesogens based on Pt(II) terpyridine coordination complexes

A series of ionic tetracoordinated Pt(II) complexes based on terpyridine ligand were synthesized and characterized. Their chemical structures were engineered by using counterions of different coordination strengths and dimensions, namely non-coordinating BF4, weakly coordinating bulky gallate units, and small and strongly coordinating chlorine (Cl). The complexes containing lipophilic gallate units exhibit low temperature liquid crystalline properties. The mesomorphic properties were investigated by polarized optical microscopy (POM), differential scanning calorimetry (DSC) and X-ray diffraction studies (SWAXS). Photophysical properties were determined in solution and condensed states

Emissive Zn(II) metallomesogen based on tridentate terpyridine ligand

A low temperature liquid crystal based on luminescent terpyridine Zn(II) complex is presented. The induction of the mesomorphic properties was achieved using a lipophilic gallate unit as ancillary ligands. The mesomorphic properties were investigated by polarised optical microscopy (POM), differential scanning calorimetry (DSC), thermogravimetric analysis (TA) and X-ray scattering (SWAXS) of bulk materials, while the optical properties of the complex were investigated in solution and in condensed liquid crystalline states

Contribuții la chimia compușilor coordinativi heteroleptici ai unor ioni 3d cu proprietăți speciale pentru aplicații în medicină

The present thesis deals with the synthesis of transition metal complexes (TMCs) containing biocompatible metal centres on the one hand. On the other hand, we have functionalized gold nanoparticles (Au NPs) functionalized with dendritic TMCs. In this thesis, we have developed new Cu(I) and Zn(II) complexes with aromatic heterocyclic nitrogen (N-donor) ligands, metallomesogens, metallodendrimers and dendronized NPs. From the new synthesized TMCs, the best performing complex will be positioned by a judicious molecular engineering in the plasmonic field of Au NPs using dendromesogens as connectors to adjust the separation between both species. The use of dendritic branches to order and position the metal-complex chromophore around the metal NPs will generate selfassembled ordered ‘soft’ arrays where antenna effect may be obtained.Pour ce travail de thèse, nous sommes intérésses dans une première partie sur la synthèse de complexes de métaux de transition (CMT) contenant des centres métalliques biocompatibles. Dans un seconde partie, nous avons fonctionnalisé des nanoparticules d'or (Au NP) avec des CMT dendritiques. Dans cette thèse, nous avons développé de nouveaux complexes de Cu(I) et Zn(II) avec des ligands hétérocycliques aromatiques azotés (N-donneurs), des métallomésogènes, des métallodendrimères et des NP dendronisées. À partir des nouveaux CMT synthétisés, le complexe le plus performant sera positionné par ingénierie moléculaire judicieuse dans le champ plasmonique des Au NPs en utilisant des dendromésogènes comme connecteurs pour ajuster la séparation entre les deux espèces. L'utilisation de branches dendritiques pour ordonner et positionner le chromophore du complexe métallique autour des NP métalliques générera des réseaux "souples" ordonnés auto-assemblés où un effet antenne pourra être obtenu

Role of the Environment Polarity on the Photophysical Properties of Mesogenic Hetero-Polymetallic Complexes

New hetero-polynuclear coordination complexes based on a pentacoordinated Zn(II) metal center with tridentate terpyridine-based ligands and monoanionic gallates functionalized with long alkyl chains containing ferrocene units were designed, synthesized and characterized using spectroscopic and analytical methods. The complexes are mesomorphic, exhibiting columnar hexagonal mesophases. The photophysical properties in a solution and in an ordered condensed state were accurately investigated and the influence of the polarity of the solvent was evidenced

Design of Nanostructured Hybrid Electrodes Based on a Liquid Crystalline Zn(II) Coordination Complex-Carbon Nanotubes Composition for the Specific Electrochemical Sensing of Uric Acid

A metallomesogen based on an Zn(II) coordination complex was employed as precursor to obtain a complex matrix nanoplatform for the fabrication of a high-performance electrochemical hybrid sensor. Three representative paste electrodes, which differ by the weight ratio between Zn(II) metallomesogen and carbon nanotubes (CNT), i.e., PE_01, PE_02 and PE_03, were obtained by mixing the materials in different amounts. The composition with the largest amount of CNT with respect to Zn complex, i.e., PE_03, gives the best electrochemical signal for uric acid detection by cyclic voltammetry in an alkaline medium. The amphiphilic structure of the Zn(II) coordination complex likely induces a regular separation between the metal centers favoring the redox system through their reduction, followed by stripping, and is characterized by enhanced electrocatalytic activity towards uric acid oxidation. The comparative detection of uric acid between the PE_03 paste electrode and the commercial zinc electrode demonstrated the superiority of the former, and its great potential for the development of advanced electrochemical detection of uric acid. Advanced electrochemical techniques, such as differential-pulsed voltammetry (DPV) and square-wave voltammetry (SWV), allowed for the highly sensitive detection of uric acid in aqueous alkaline solutions. In addition, a good and fast amperometric signal for uric acid detection was achieved by multiple-pulsed amperometry, which was validated by urine analysis

Pentacoordinated Liquid Crystalline Zn(II) Complex Organized in Smectic Mesophase: Synthesis, Structural and Electrochemical Properties

The synthesis and structural characterization of a new liquid crystalline coordination complex based on pentacoordinated Zn(II) metal centre with the coordination fulfilled by the tridentate chelating N^N^N 2,2′;6′,2″-terpyridine ligand and two monoanionic gallates decorated with several long alkyl chains is described. The mesomorphic properties were accurately investigated by small- and wide-angle X-ray scattering studies. Despite the bulky coordination around the metal centre, the complex self-organizes into a smectic phase and, based on the structural and geometrical parameters, a model for the supramolecular organization in the liquid crystalline phase is proposed. Electrochemical investigations showed the importance of the molecular structure of the coordination complex in enhancing its aqueous sensing capacities: the bulky organic ligands form an organic shell separating the metal centres and favouring the redox system through their reduction followed by stripping

Playing with Pt II and Zn II Coordination to Obtain Luminescent Metallomesogens

International audienceBlue-green luminescent terpyridine-containing Pt II and Zn II complexes are reported. Equipped with lipophilic gallate units, which act as monodentate ancillary coordinating ligands and/or as anions, they display low-temperature mesomorphic properties (lamello-columnar and hexagonal mesophases for Pt II and Zn II complexes, respectively). The mesomorphic properties were investigated by polarised optical microscopy, differential scanning calorimetry, thermogravimetric analysis and X-ray scattering of bulk materials and oriented thin films. The model of self-assembly into the lamello-columnar phase of the Pt II complex has been described in detail. The optical properties of the complexes were investigated in the liquid and condensed liquid crystalline states, highlighting the delicate balance between the role of the metal in determining the type of excited state responsible for the emission, and the role of the ancillary ligand in driving intermolecular interactions for proper mesophase formation

Pentacoordinated Liquid Crystalline Zn(II) Complex Organized in Smectic Mesophase: Synthesis, Structural and Electrochemical Properties

The synthesis and structural characterization of a new liquid crystalline coordination complex based on pentacoordinated Zn(II) metal centre with the coordination fulfilled by the tridentate chelating N^N^N 2,2′;6′,2″-terpyridine ligand and two monoanionic gallates decorated with several long alkyl chains is described. The mesomorphic properties were accurately investigated by small- and wide-angle X-ray scattering studies. Despite the bulky coordination around the metal centre, the complex self-organizes into a smectic phase and, based on the structural and geometrical parameters, a model for the supramolecular organization in the liquid crystalline phase is proposed. Electrochemical investigations showed the importance of the molecular structure of the coordination complex in enhancing its aqueous sensing capacities: the bulky organic ligands form an organic shell separating the metal centres and favouring the redox system through their reduction followed by stripping