Preparation of Cu(NN)(PP)+ derivatives has been systematically investigated starting from two libraries of phenanthroline (NN) derivatives and bis-phosphine (PP) ligands, namely, (A) ...1,10-phenanthroline (phen), neocuproine (2,9-dimethyl-1,10-phenanthroline, dmp), bathophenanthroline (4,7-diphenyl-1,10-phenanthroline, Bphen), 2,9-diphenethyl-1,10-phenanthroline (dpep), and 2,9-diphenyl-1,10-phenanthroline (dpp); (B) bis(diphenylphosphino)methane (dppm), 1,2-bis(diphenylphosphino)ethane (dppe), 1,3-bis(diphenylphosphino)propane (dppp), 1,2-bis(diphenylphosphino)benzene (dppb), 1,1′-bis(diphenylphosphino)ferrocene (dppFc), and bis(2-diphenylphosphino)phenyl ether (POP). Whatever the bis-phosphine ligand, stable heteroleptic Cu(NN)(PP)+ complexes are obtained from the 2,9-unsubstituted-1,10-phenanthroline ligands (phen and Bphen). By contrast, heteroleptic complexes obtained from dmp and dpep are stable in the solid state, but a dynamic ligand exchange reaction is systematically observed in solution, and the homoleptic/heteroleptic ratio is highly dependent on the bis-phosphine ligand. Detailed analysis revealed that the dynamic equilibrium resulting from ligand exchange reactions is mainly influenced by the relative thermodynamic stability of the different possible complexes. Finally, in the case of dpp, only homoleptic complexes were obtained whatever the bis-phosphine ligand. Obviously, steric effects resulting from the presence of the bulky phenyl rings on the dpp ligand destabilize the heteroleptic Cu(NN)(PP)+ complexes. In addition to the remarkable thermodynamic stability of Cu(dpp)2BF4, this negative steric effect drives the dynamic complexation scenario toward almost exclusive formation of homoleptic Cu(NN)2+ and Cu(PP)2+ complexes. This work provides the definitive rationalization of the stability of Cu(NN)(PP)+ complexes, marking the way for future developments in this field.
Bridge the gap: Rigid π‐conjugated bridges such as the ethynyl spacers, are effective for connecting the phthalocyanine π system to the conduction band of TiO2. A series of zinc phthalocyanine ...photosensitizers with carboxyethynyl anchoring groups have been synthesized. Solar cells sensitized with the pictured compound exhibit record efficiencies of 5.5 % and 6.1 % under 100 (1 sun irradiation) and 9.5 mW cm−2, respectively.
Dyeing together: An efficient panchromatic dye‐sensitized solar cell is constructed by using a “molecular cocktail” composed of an organic dye and a zinc phthalocyanine (see picture). The use of ...multiple, complementary dyes (cosensitization) is an important step towards solar cells that operate across the full spectrum of solar irradiation.
Exfoliation of graphite was achieved using a zinc phthalocyanine oligomer that is also an electron donor. The resulting functionalized graphene material was investigated by Raman and electron ...spectroscopy and was trialed in a photoelectrochemical cell.
A family of triarylamine–fullerene conjugates has been synthesized and shown to self-assemble upon light stimulation in chlorinated solvents. This light-induced process primarily involves excitation ...of triarylamine derivatives, which then oxidize and stack with their neutral counterparts to form charge transfer complexes in the form of p-conducting channels, while fullerenes are consequently enforced in coaxial n-conducting columnar arrangements. These supramolecular heterojunctions can be organized over very long distances in micrometric fibers when a controlled amount of photons is provided from a white light source to initiate the process. Surprisingly, when sunlight or UV light is used instead, the nanostructuration leads to monodisperse spherical objects due to the nature of the nucleation–growth process involved in the stacks formation. This control over the supramolecular morphology of organic self-assemblies using the nature of light is of general interest for the design of functional responsive materials.
The size and shape of nanoparticles are of prominent importance for their biological activities and for their application as smart drug delivery systems. Thus, synthetic designs allowing divergent ...synthesis of nanoscale materials with controlled size, morphology, and surface chemistry are currently highly desirable, but they remain a major challenge. Herein, we report a simple method for the creation of supramolecular diversity from structurally related diacetylenic-based glycolipids. We have found that neoglycolipids with an amide function between the hydrophilic and hydrophobic part of the amphiphile afford tridimensional micelles, while those having a triazole self-organize into 1D-nanotubes. Additionally, at higher concentrations, the clicked amphiphiles form hydrogels through three-dimensional networks of bundled nanotubes. Photopolymerization of the obtained nanomaterials leads to the formation of conjugated polydiacetylene backbone of alternating enyne groups, which rigidify glyconanomaterial structures enhancing their physical stability. The obtained nanostructures were extensively characterized using transmission electron microscopy (TEM), scanning electron microscopy (SEM), and atomic force microscopy (AFM) techniques, enabling the confirmation of the formation of tubular structures in water for all triazolo-substituted neoglycolipids and micellar structures for the glycolipid containing an amide group. This fact refutes the so-called isosteric character of 1,2,3-triazole and amide groups, at least, at the supramolecular level and point out to the possibility of using the CuAAC between azides and alkynes to create supramolecular diversity at the nanoscale. The functionality of the gel was, moreover, evaluated as a nanocontainer for the incarceration and controlled release of the antitumoral topotecan.
Mechanically interlocked molecules (MIMs) have emerged as intriguing building blocks for the construction of stimuli‐responsive devices and materials. A particularly interesting and well‐implemented ...subclass of MIMs is composed of symmetric bistable c2daisy chain rotaxanes. Topologically, they consist in the double thread of two symmetric macrocycles that are covalently linked to an axle bearing two switchable stations and a bulky stopper to avoid unthreading. Herein we report the synthesis and characterization of a series of unsymmetric bistable c2daisy chain rotaxanes that present two different electroactive units as stoppers (an electron donor triarylamine and an electron acceptor perylene bisimide unit). Using a combination of 1D and 2D NMR along with cyclic voltammetry, we demonstrate that the pH actuation of the mechanical bond can be used to modulate the electrochemical properties of the bistable c2daisy chain rotaxanes when switching between the contracted and extended forms.
pH‐Switchable c2daisy chain rotaxanes that present two different electroactive units as stoppers have been synthesized and fully characterized. Their actuation between the contracted and extended forms leads to a modification of their electrochemical properties.
Let it shine! The impact of the anchoring group on photovoltaic performance by a series of phthalocyanine sensitisers (see figure) has been demonstrated.
A series of unsymmetrical zinc ...phthalocyanines bearing an anchoring carboxylic function linked to the phthalocyanine ring through different spacers were designed for dye‐sensitised solar cells (DSSC). The modification of the spacer group allows not only a variable distance between the dye and the nanocrystalline TiO2, but also a distinct orientation of the phthalocyanine on the semiconductor surface. The photovoltaic data show that the nature of the spacer group plays a significant role in the electron injection from the photo‐excited dye into the nanocrystalline TiO2 semiconductor, the recombination rates and the efficiency of the cells. The incident monochromatic photon‐to‐current conversion efficiency (IPCE) for phthalocyanines bearing an insulating spacer is as low as 9 %, whereas for those with a conducting spacer an outstanding IPCE 80 % was obtained.
Let it shine! The impact of the anchoring group on photovoltaic performance by a series of phthalocyanine sensitisers (see figure) has been demonstrated.
Supramolecular organic electronics rests on the use of bottom‐up chemical self‐assembly processes in order to design conducting components on the 5–100 nm scale. The challenges in this field are both ...the construction of 1D‐nanostructures displaying optimized transport properties and their precise connections to electrodes. The present Research News highlights important advances in such materials regarding their electrical performances, from semiconductors to organic metals, but also regarding their processability. In particular, by externally controlling light‐responsive supramolecular polymerization processes, and by using appropriate methods of casting with an applied electric field, it becomes possible to pre‐determine the accurate positioning of organic interconnects within patterned nano‐circuitry. These strategies using external stimuli to obtain addressability, thus hold promising alternatives to other conducting materials such as carbon nanotubes for further technological applications in nanosciences.
Recent advances in supramolecular electronics show that self‐assembled nanowires made of π‐stacked molecules can achieve electrical properties competing with those encountered in the other categories of conducting materials, including carbon nanotubes. In addition, by externally controlling the supramolecular polymerization processes with light and electric field, it becomes possible to accurately position these electroactive wires at nanoscale. The graphical represents triarylamine‐based supramolecular interconnects of 80 nm length specifically linking two gold electrodes in a pre‐determined position.
The effect of chenodeoxycholic acid as a coadsorbent on TiO2 nanocrystalline solar cells incorporating phthalocyanine sensitizers was studied under various conditions. Adding chenodeoxycholic acid ...onto TiO2 nanoparticles not only reduces the adsorption of phthalocyanine sensitizers but also prevents sensitizer aggregation, leading to different photovoltaic performance. The inspection of IPCE and absorption spectra showed that the load of phthalocyanine sensitizers is strongly dependent on the molar concentration of chenodeoxycholic acid coadsorbent. The open circuit voltage of the solar cells with chenodeoxycholic acid coadsorbent increases due to the enhanced electron lifetime in TiO2 nanoparticles coupled with the band edge shift of TiO2 to negative potentials.
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![Unsymmetric Bistable [c2]Da...](http://api.summon.serialssolutions.com/2.0.0/image/issn/XR4PS5YY4K/1434-193X/small "Unsymmetric Bistable [c2]Daisy Chain Rotaxanes which Combine Two Types of Electroactive Stoppers")
