Carlos

High-mobility short-channel organic thin-film transistors fabricated using a dinaphtho[2,3-b:2′,3′-f]thieno[3,2-b]­thio­­phene (DNTT) precursor (5,14-N-­phenylmaleimide DNTT, endo-isomer-rich fraction) and polystyrene (PS) blends are reported. The DNTT grains are “single-crystal”-like and the field-effect mobility of the devices ranges up to 4.7 cm² V⁻¹ s⁻¹. The PS layer functions as a hydrophobic passivation layer on the Si/SiO₂ substrate.

A facile surfactant-assisted bottom-up synthetic method to prepare a series of freestanding ultrathin 2D M-TCPP (M = Zn, Cu, Cd or Co, TCPP = tetrakis(4-carboxyphenyl)porphyrin) nanosheets with a thickness of sub-10 nm is developed. As a proof-of-concept application, some of them are successfully used as new platforms for DNA detection. The Cu-TCPP nanosheet-based sensor shows excellent fluorescent sensing performance and is used for the simultaneous detection of multiple DNA targets.

The possibility to change the molecular assembled structures of organic and organometallic materials through mechanical stimulation is emerging as a general and powerful concept for the design of functional materials. In particular, the photophysical properties such as photoluminescence color, quantum yield, and emission lifetime of organic and organometallic fluorophores can significantly depend on the molecular packing, enabling the development of molecular materials with mechanoresponsive luminescence characteristics. Indeed, an increasing number of studies have shown in recent years that mechanical force can be utilized to change the molecular arrangement, and thereby the optical response, of luminescent molecular assemblies of π-conjugated organic or organometallic molecules. Here, the development of such mechanoresponsive luminescent (MRL) molecular assemblies consisting of organic or organometallic molecules is reviewed and emerging trends in this research field are summarized. After a brief introduction of mechanoresponsive luminescence observed in molecular assemblies, the concept of “luminescent molecular domino” is introduced, before molecular materials that show turn-on/off of photoluminescence in response to mechanical stimulation are reviewed. Mechanically stimulated multicolor changes and water-soluble MRL materials are also highlighted and approaches that combine the concept of MRL molecular assemblies with other materials types are presented in the last part of this progress report.

Mechanoresponsive luminescence exhibited by molecular materials is an emerging topic in materials science. The background of this research field is described, and the concept of “luminescent molecular domino”, turn-on/off behavior, multicolor changes, and water-soluble mechanoresponsive luminescent materials are reviewed. Approaches to covalently attach such materials to other materials are also introduced.

Boron–nitrogen dative bonds provide a suitable motif for reversible, yet strong and directed interactions, leading to the highly efficient self-assembly of small organic building blocks into supramolecular cage structures. A bipyramidal [2+3] assembly, as the first example of a supramolecular cage mediated by BN dative bonds that exists as a discrete species in solution, is quantitatively obtained from a tribenzotriquinacene-based trisboronate ester and 1,4-diazabicyclo[2.2.2]octane. Thermodynamic equilibria of cage formation are investigated by isothermal titration calorimetry and fully reversible cage opening can be observed at elevated temperatures.

Cage creation: Boron–nitrogen dative bonds mediated the formation of supramolecular cages with bipyramidal shapes (see figure). Fully reversible assembly and disassembly could be achieved with changes in temperature.

The global energy demand is increasing at the same time as fossil fuel resources are dwindling. Consequently, the search for alternative energy sources is a major topic worldwide. Solar energy is one of the most promising, effective and emission-free energy sources. However, the energy has to be stored to compensate the fluctuating availability of the sun and the actual energy demand. Photo-rechargeable electric energy storage systems may solve this problem by immediately storing the generated electricity. Different combinations of solar cells and storage devices are possible. High efficiencies can be achieved by the combination of dye-sensitized solar cells (DSSC) and capacitors. However, other hybrid devices including DSSCs or organic photovoltaic systems and redox flow batteries, lithium ion batteries and metal air batteries are playing an increasing role in this research field. This Progress Report reviews the state of the art research of photo-rechargeable batteries based on organic solar cells, as well as storage modules.

Recent developments in the investigation of solar rechargeable electric energy storage systems are reviewed. Details of operation and performance are provided for organic hybrid devices of different solar cell types (e.g., dye sensitized solar cells or bulk heterojunction solar cells) and several energy storage systems (e.g., supercapacitors, redox flow batteries or metal air batteries).

A new bimetallic lanthanide metal-organic framework [Eu_0.5Tb_1.5(FDA)₃] (H₂FDA = 2,5-furandicarboxylic acid) exhibits high-sensitivity luminescent sensing of mixtures of organic compounds and can work over a large range of volume ratios. The self-calibrating behavior of this color-gradient luminescent sensor is presented for the first time.

Phosphorus has been successfully fused into a classic rhodamine framework, in which it replaces the bridging oxygen atom to give a series of phosphorus-substituted rhodamines (PRs). Because of the electron-accepting properties of the phosphorus moiety, which is due to effective σ*–π* interactions and strengthened by the inductivity of phosphine oxide, PR exhibits extraordinary long-wavelength fluorescence emission, elongating to the region above 700 nm, with bathochromic shifts of 140 and 40 nm relative to rhodamine and silicon-substituted rhodamine, respectively. Other advantageous properties of the rhodamine family, including high molar extinction coefficient, considerable quantum efficiency, high water solubility, pH-independent emission, great tolerance to photobleaching, and low cytotoxicity, stay intact in PR. Given these excellent properties, PR is desirable for NIR-fluorescence imaging in vivo.

Good PR: Phosphorus-substituted rhodamine (PR; see figure) exhibits extraordinary long-wavelength fluorescence emission, elongating to the region above 700 nm, with bathochromic shifts of 140 and 40 nm relative to rhodamine and Si-rhodamine, respectively. This behavior is ascribed to the electron-accepting character of the phosphorus moiety. Hence, PR displays superior characteristics for in vivo fluorescence imaging.

A unique Al^III-based metal–organic framework (467-MOF) with two types of square channels has been designed and synthesized by using a flexible tricarboxylate ligand under solvothermal conditions. 467-MOF exhibits superior thermal and chemical stability and, moreover, shows high CO₂ sorption selectivity over H₂, with a selectivity, based on the ideal adsorbed solution theory (IAST) of approximately 45 at 273 or 293 K. Furthermore, its solvent-dependent photoluminescence makes it an applicable sensor in the detection of nitrobenzene explosives through fluorescence quenching.

Ready, willing, and stable: A unique Al^III-based metal–organic framework (MOF) material based on a flexible tricarboxylate ligand has been synthesized. The MOF shows exceptional stability and potential applications as a selective adsorbent and nitrobenzene sensor.

Organic molecules of intrinsic microporosity (OMIMs) are structurally constructed to not pack tightly. Consequently, only weak interactions between OMIM molecules can occur, which is the reason that almost all OMIMs have been described and investigated in their amorphous states. For the same reason it is very difficult to grow single crystals of OMIMs for X-ray structural analysis. Here we describe four different polymorphs of an OMIM that was before only described in the amorphous state.

Not too frustrated! Organic molecules of intrinsic microporosity (OMIMs) are constructed to not pack by strong interactions (the so-called frustrated packing). One example is given which shows how frustration can be circumvented and how to obtain single-crystal X-ray structures with large intrinsic pore volumes.

Tetranuclear, intensely blue-coloured Cu^I complexes were synthesised in which two Cu₂X₃⁻ units (X=Br or I) are bridged by a dicationic GFA (guanidino-functionalised aromatic) ligand. The UV/Vis spectra show a large metal-to-ligand charge-transfer (MLCT) band around 638 nm. The tetranuclear “low-temperature” complexes are in a temperature-dependent equilibrium with dinuclear Cu^I “high-temperature” complexes, which result from the reversible elimination of two CuX groups. A massive thermochromism effect results from the extinction of the strong MLCT band upon CuX elimination with increasing temperature. For all complexes, quantum chemical calculations predict a small and method-dependent energy difference between the possible electronic structures, namely Cu^I and dicationic GFA ligand (closed-shell singlet) versus Cu^II and neutral GFA ligand (triplet or broken-symmetry state). The closed-shell singlet state is disfavoured by hybrid-DFT functionals, which mix in exact Hartree–Fock exchange, and is favoured by larger basis sets and consideration of a polar medium.

Colorful copper: A massive charge-transfer band is switched on by CuX (X=Br, I) addition to a dinuclear Cu^I complex with bridging dicationic tetrakisguanidine ligands.

The synthesis of five novel distyrylbenzene (DSB) derivatives, featuring a central tetraphenylbenzene core, is reported. The targets show aggregation-induced emission (AIE), which, however, is substituent-dependent. For the pure hydrocarbon and derivatives that do not carry (+M) or (−M) substituents, classic AIE behavior is observed, that is, the DSBs are non-fluorescent in solution, but are highly fluorescent in cold matrices, upon aggregate formation in poor solvents and in the solid, crystalline state. If aldehyde or dibutylamino groups are attached in the para-position of the DSB unit, non-classic AIE-phores result. These are fluorescent both in dilute solution as well as in the solid state. Prolonged irradiation of the targets leads to benzotetraphene derivatives by a double cyclization.

Aggregate to shine: Proper substitution of tetraphenyldistyrylbenzenes allows the tuning of their aggregation-induced emission properties. Virtually non-fluorescent in solution, derivatives with smaller π-systems exhibit tremendous fluorescence turn-on in cold matrices, upon aggregate-formation in poor solvents and in the solid, crystalline state. Prolonged irradiation leads to the selective formation of benzotetraphene derivatives.