The synthesis and luminescence properties of new platinum and iridium complexes

The work of this thesis is focused on the synthesis and the photoluminescence studies of new 3 raw transition metal complexes (Ir(III), Pt(II), Pd(II)) . The main objective is to obtain new phosphorescent materials for applications such as organic light emitting diodes (OLEDs) and bio- imaging. The incorporation of chromophores such as pyrene and naphthalimide into fac-Ir-(thpy)3 complex will first be presented. The synthesis, by C–H activation, of the new complex will also be studied. New ultra-rigid organometallic complexes will then be developed. The synthesis and the photoluminescence analysis of these tetradentate platinum and palladium complexes will be described. Finally, a study of new iridium complexes incorporating benzimidazoles (iso)-quinoline and bis-benzimidazole ligands sensitive to pH variations will be made

Guest‐selective gate‐opening by pore engineering of two‐dimensional Kagomè lattice porous coordination polymers

Porous coordination polymers (PCPs) with pore decoration have been used as materials for excellent storage and separation functions. The cooperative properties of flexible PCPs can be utilized to achieve the separation of mixtures of gaseous molecules having highly similar properties. The key to efficient molecular recognition and separation lies in increasing the degrees of freedom of the structure without sacrificing the stability of the system. However, the mechanism study of such behavior is still scarce in the literature. Here, we focused on PCPs with two-dimensional Kagomè lattice structures and functionalized the pores with various alkoxy pendant groups; this facilitated systematic tuning of the pore aperture size, the interlayer spacing, as well as the interactions between the host and adsorbed molecules. The combination of characterization techniques allowed us to observe a unique deformation of the lattice upon gas sorption, allowing the separation of gas molecules with similar physicochemical properties, such as propane and propylene

Understanding the multiscale self-assembly of metal–organic polyhedra towards functionally graded porous gels

Spatial heterogeneity and gradients within porous materials are key for controlling their mechanical properties and mass/energy transport, both in biological and synthetic materials. However, it is still challenging to induce such complexity in well-defined microporous materials such as crystalline metal–organic frameworks (MOFs). Here we show a method to generate a continuous gradient of porosity over multiple length scales by taking advantage of the amorphous nature of supramolecular polymers based on metal–organic polyhedra (MOPs). First, we use time-resolved dynamic light scattering (TRDLS) to elucidate the mechanism of hierarchical self-assembly of MOPs into colloidal gels and to understand the relationship between the MOP concentrations and the architecture of the resulting colloidal networks. These features directly impact the viscoelastic response of the gels and their mechanical strength. We then show that gradients of stiffness and porosity can be created within the gel by applying centrifugal force at the point of colloidal aggregation. These results with the creation of asymmetric and graded pore configuration in soft materials could lead to the emergence of advanced properties that are coupled to asymmetric molecule/ion transport as seen in biological systems

Formulation of metal-organic framework inks for the 3D printing of robust microporous solids

International audienceMetal-organic frameworks (MOFs) are a fast-growing class of highly porous materials owing to their exceptional structural diversity. A consequent effort has been deployed during the past few years for rationalizing the preparation of the most promising MOF structures, in view of their applications at larger scale. Still, their shaping represents a major bottleneck due to the difficulty to conciliate high porosity and adequate mechanical resistance to withstand overtime damaging stresses.3D printing is a promising technology as it allows the fast prototyping of materials at the macroscale.1 Herein, a 3D printer was modified to prepare a variety of MOF-based solids with controlled morphology from shear-thinning inks containing a cellulose-derived binder. Four benchmark MOFs were tested: HKUST-1, CPL-1, ZIF-8 and UiO-66-NH2. All solids are mechanically stable up to 0.6 MPa of uniaxial compression and highly porous, with BET specific surface areas lowered by 0 to -25%. Furthermore, these solids were applied to high pressure sorption (CH4, C2H4 and C2H6) and presented performances in line with the literature

A Pseudo Five-Fold Symmetrical Ligand Drives Geometric Frustration in Porous Metal-Organic and Hydrogen Bonded Frameworks

Reticular framework materials thrive on designability, but unexpected reaction outcomes are crucial in exploring new structures and functionalities. By combining “incompatible” building blocks, we employed geometric frustration in reticular materials leading to emergent structural features. The combination of a pseudo C5 symmetrical organic building unit based on a pyrrole core, with a C4 symmetrical copper paddlewheel synthon led to three distinct frameworks by tuning the synthetic conditions. The frameworks show structural features typical for geometric frustration: self-limiting assembly, internally stressed equilibrium structures and topological defects in the equilibrium structure, which manifested in the formation of a hydrogen bonded framework, distorted and broken secondary building units and dangling functional groups, respectively. The influence of geometric frustration on the CO2 sorption behavior and the discovery of a new secondary building unit shows geometric frustration can serve as a strategy to obtain highly complex porous frameworks

Understanding of the Multiscale Self-Assembly of Metal-Organic Polyhedra Towards Functionally Graded Porous Gels

Spatial heterogeneity and gradients within porous materials are key for controlling their mechanical properties and mass/energy transport, both in biological and synthetic materials. However, it is still challenging to induce such complexity in well-defined microporous materials such as crystalline metal-organic frameworks (MOFs). Here we show a method to generate a continuous gradient of porosity over multiple length scales by taking advantage of the amorphous nature of supramolecular polymers based on metal-organic polyhedra (MOPs). First, we use time-resolved dynamic light scattering (TRDLS) to elucidate the mechanism of hierarchical self-assembly of MOPs into colloidal gels and to understand the relationship between the MOP concentrations and the architecture of the resulting colloidal networks. These features directly impact on the viscoelastic response of the gels and their mechanical strength. We then show that gradients of stiffness and porosity can be created within the gel by applying centrifugal force at the point of colloidal aggregation. These results with the creation of asymmetric and graded pore configuration in soft materials could lead to the emergence of advanced properties that are coupled to asymmetric molecule/ion transport as seen in biological systems.<br /

Hysteresis in the Gas Sorption Isotherms of Metal-Organic Cages Accompanied by Subtle Changes in Molecular Packing

Structural deformation in response to gas sorption is rarely observed for porous molecular solids, when compared to porous framework materials. Here, we describe the effect of chemical modification on the exterior of lantern-type metal-organic cages on the emergence and then disappearance of cooperative gas uptake. The results suggest that supramolecular design of ligands can be used to reveal this behaviour

Hysteresis in the gas sorption isotherms of metal–organic cages accompanied by subtle changes in molecular packing

Structural deformation in response to gas sorption is rarely observed for porous molecular solids, when compared to porous framework materials. Here, we describe the effect of chemical modification on the exterior of lantern-type metal–organic cages on the emergence and then disappearance of cooperative gas uptake. The results suggest that supramolecular design of ligands can be used to reveal this behaviour

Enhanced Gas Adsorption in HKUST-1@Chitosan Aerogels, Cryogels, and Xerogels : An Evaluation Study

International audienceThis study investigates the use of chitosan hydrogel microspheres as a template for growing an extended network of MOF-type HKUST-1. Different drying methods (supercritical CO2, freeze-drying, and vacuum drying) were used to generate three-dimensional polysaccharide nanofibrils embedding MOF nanoclusters. The resulting HKUST-1@Chitosan beads exhibit uniform and stable loadings of HKUST-1 and were used for the adsorption of CO2, CH4, Xe, and Kr. The maximum adsorption capacity of CO2 was found to be 1.98 mmol·g–1 at 298 K and 1 bar, which is significantly higher than those of most MOF-based composite materials. Based on Henry’s constants, thus-prepared HKUST-1@CS beads also exhibit fair selectivity for CO2 over CH4 and Xe over Kr, making them promising candidates for capture and separation applications

Integrated Soft Porosity and Electrical Properties of Conductive-on-Insulating Metal-Organic Framework Nanocrystals

A one-stone, two-bird method to integrate the soft porosity and electrical properties of distinct metal–organic frameworks (MOFs) into a single material involves the design of conductive-on-insulating MOF (cMOF-on-iMOF) heterostructures that allow for direct electrical control. Herein, we report the synthesis of cMOF-on-iMOF heterostructures using a seeded layer-by-layer method, in which the sorptive iMOF core is combined with chemiresistive cMOF shells. The resulting cMOF-on-iMOF heterostructures exhibit enhanced selective sorption of CO₂ compared to the pristine iMOF (298 K, 1 bar, S[CO₂/H₂] from 15.4 of ZIF-7 to 43.2–152.8). This enhancement is attributed to the porous interface formed by the hybridization of both frameworks at the molecular level. Furthermore, owing to the flexible structure of the iMOF core, the cMOF-on-iMOF heterostructures with semiconductive soft porous interfaces demonstrated high flexibility in sensing and electrical “shape memory” toward acetone and CO₂. This behavior was observed through the guest-induced structural changes of the iMOF core, as revealed by the operando synchrotron grazing incidence wide-angle X-ray scattering measurements